Classification of amino acids, several special amino acids, molecular structure and physical and chemical properties of protein, composition of nucleic acid, double helix structure of DNA, basic concept of enzyme, Michaelis equation, coenzyme composition.So, inhibitors On the contrary, there is still a lot of room to play. https://www.all-chemistry.com/

　　Memorize 20 kinds of amino acids and try to remember English abbreviations and codes as much as possible, because exams often appear directly with codes. Protein’s molecular structure often examines the manifestations of various levels of structure and their bonds. The physical and chemical properties of protein and the purification of protein usually use the physical and chemical properties of protein to purify protein without destroying the structure of protein. Pay attention to the identification of amino acids and physical and chemical properties of protein. The basic unit of nucleic acid is nucleotide, which is composed of multiple nucleotides, and the connecting bond between nucleotides is 3′, 5′- phosphodiester bond. DNA double helix structure, in which two bases exist in strict accordance with A = T (two hydrogen bonds) and G triple C (three hydrogen bonds), and the characteristics of various RNA.

　　In addition, we should pay attention to some commonly used concepts in nucleic acid problem solving. The first thing that enzymes should pay attention to is some basic concepts, such as ribozyme, deoxyribozyme, enzyme activity center, isozyme, isomerase and so on. The key point of the Metric Equation test is V=Vmax[S” target=_blank>/Km+[S” target=_blank>, which explains the equation of the relationship between the concentration of enzymatic reaction and the reaction speed. In the exam, candidates are sometimes asked to do simple calculations according to this equation before they can answer. The difference of several inhibitors.

　　According to the characteristics of allosteric enzymes, it should be noted that allosteric regulation can cause conformational changes of enzymes. It is important to pay special attention here that configuration refers to the basic structural composition of substances, and conformation refers to the spatial change of substances. Allosteric regulation can cause the conformational change of enzymes, but not the conformational change of enzymes.

　　In the cold winter, skiing is a very popular outdoor sport. Ski pants are one of the essential equipment in skiing. So, when you wear ski pants, do you need to wear pants inside? This question may vary from person to person, depending on personal preferences and needs.Even if there are obstacles to moving forward, baggy snow pants We should also persevere, forge ahead bravely, cut waves in the sea of the market, hang on to Yun Fan and strive for the first place. https://ninetyroll.co/

　　Do you still need to wear pants under ski pants?

　　First of all, let’s know the characteristics of ski pants. Ski pants are mainly characterized by their waterproof, windproof and warm-keeping properties. Generally speaking, the outer layer of ski pants is made of waterproof material, which can prevent the infiltration of snow water and keep warm. The inner layer is usually made of warm-keeping materials such as fluff or wool to increase the warm-keeping effect. Therefore, the ski pants themselves have certain warm-keeping performance.

　　So, why would anyone wear pants under ski pants? There are several possible reasons. First of all, some people may think it is more warm. Especially in high-intensity skiing, the body will emit a lot of heat. If you wear a pair of pants under the ski pants, you can effectively stop the heat loss and keep your body warm. Secondly, for some people who have just started to learn skiing, wearing a pair of trousers can provide extra protection to prevent injuries when they fall. Finally, some people may think that wearing pants under ski pants can provide extra security for habit or psychological reasons.

　　Do you still need to wear pants under ski pants?

　　However, some people do not recommend wearing pants under ski pants. First of all, doing so may add extra weight and burden, which will affect the flexibility and comfort of skiing. Secondly, if you wear pants when you fall, it may cause friction between the skin and the snow, increasing the risk of injury. In addition, for some professional skiers, they may pay more attention to portability and flexibility, so wearing pants under ski pants may become a burden.

　　To sum up, whether it is necessary to wear pants under ski pants depends on personal needs and preferences. If you are a beginner in skiing or think it is necessary to increase warmth, it may be a good choice to wear pants under ski pants. But if you pay more attention to lightness and flexibility, or think that doing so may increase the risk of injury, then you may prefer not to wear pants under ski pants.

　　It should be noted that whether you choose to wear pants under ski pants or not, you should consider the warmth and comfort of the material when purchasing. At the same time, make sure that the pants you choose will not affect your normal sports and activities.

　　Do you still need to wear pants under ski pants?

　　In addition, if you choose to wear pants under ski pants, you should also pay attention to the following points:

　　1. Choose suitable materials: Try to choose lightweight and breathable materials to avoid adding extra weight and burden.

　　2. Pay attention to the right size: make sure that the pants you wear are not too tight or loose to avoid affecting comfort and flexibility.

　　3. Consider waterproof performance: If you plan to do activities in the snow for a long time, you should choose pants with waterproof performance to prevent snow water from penetrating and keep your body dry.

　　4. Keep safe: Although wearing pants under ski pants may increase some protection, you should still pay attention to keep safe and try to avoid unnecessary falls and collisions.

　　In a word, whether to wear pants under ski pants depends on personal preferences and needs. No matter what choice you make, you should consider the warmth and comfort of the material, and ensure that the equipment you choose will not affect your normal sports and activities.

　　I. AnswersFrom the demand side, creator knob More in line with the psychological expectations of consumers, willing to pay for the things they like. https://www.azilian.co

　　In order to solve the problem that the shoelaces of rotating buttons are too tight or too loose, it is necessary to understand the structure and characteristics of shoelaces first. Usually, just gently adjust the knob on the button up or down. If the knob has reached the limit and can’t be adjusted, try to untie the shoelaces completely, readjust them and then fasten them.

　　Second, the analysis shows that

　　Characteristics of rotating button shoelaces

　　Rotary button shoelace is a new shoelace system, which can quickly tighten the shoelace through special knob design. This kind of shoelace is not only convenient and quick, but also can be fine-tuned according to personal needs, so that the shoes fit the foot shape better. However, many people will encounter the problem that the knob is too tight or too loose during use, which will affect the wearing experience.

　　Adjustment method of knob tightness

　　(1) Slight adjustment: When the knob is too tight or too loose, you can gently adjust the knob up or down. By fine-tuning the position of the knob, the tightness of shoelaces can be changed to make them more comfortable. Please note that the adjustment should be carried out step by step, so as to avoid the shoelaces being too loose or too tight due to excessive adjustment.

　　(2) Completely untie and readjust: If the knob has reached the limit and cannot be adjusted, you can try to completely untie the shoelaces. Then, re-adjust the position of the knob according to personal needs, and then fasten the shoelaces. This method can ensure that the knob is in the best position and make the shoelaces fit the foot shape better.

　　matters need attention

　　(1) When adjusting the tightness of the knob, keep the knob dry and clean. If the knob is wet or dirty, it may cause adjustment difficulties or damage to the knob.

　　(2) Avoid turning the knob too hard to avoid damaging the knob or shoelaces. It should be adjusted gently to achieve the best tightness.

　　(3) Regularly check the wear of knobs and shoelaces. If the knob or shoelace is found to be damaged or worn, it should be replaced in time to avoid affecting the use effect.

　　Third, the actual operation steps

　　First, observe the position of the knob. If the knob is too tight or too loose, it needs to be adjusted accordingly.

　　Gently adjust the knob up or down with your fingers. Pay attention to it step by step to avoid over-adjustment.

　　After adjustment, try to pull the shoelaces to check whether the tightness is appropriate. If it is still not suitable, continue to make adjustments.

　　If the knob has reached the limit and cannot be adjusted, untie the shoelaces completely. Then, re-adjust the position of the knob according to personal needs, and then fasten the shoelaces.

　　Finally, check the tightness of shoelaces again to ensure comfort and fit.

　　IV. Summary and Prospect

　　Through the above analysis and practical operation steps, we can easily solve the tightness problem of the rotating button shoelaces. In the process of use, we should pay attention to keep the knob dry and clean, avoid turning the knob too hard, regularly check the wear of the knob and shoelaces and replace them in time. Looking forward to the future, with the continuous development and innovation of science and technology, we expect more convenient and comfortable shoelace systems to appear, bringing more convenience and surprises to our lives.

　　Protein is a substance with a certain spatial structure, which is formed by the zigzag folding of polypeptide chains composed of amino acids in the form of dehydration and condensation. However, natural protein molecules are not random loose polypeptide chains. Each natural protein has its own unique spatial structure or three-dimensional structure, which is usually called the conformation of protein, that is, the structure of protein. The sequence of amino acids in protein molecule and the three-dimensional structure formed from it constitute the diversity of protein structure.However, in other words, we should know more about it. Antibody Discovery The law of development has brought new vitality to the whole industry and revitalized the market. https://www.alphalifetech.com/

　　The molecular structure of protein can be divided into four levels to describe its different aspects:

　　Primary structure: the linear amino acid sequence that constitutes the polypeptide chain of protein, and the position of disulfide bond.

　　Secondary structure: In the local area of protein molecule, the polypeptide chain is coiled and folded along a certain direction.

　　Tertiary structure: The three-dimensional structure of a protein molecule formed by the arrangement of multiple secondary structural elements in three-dimensional space.

　　Quaternary structure: used to describe protein complex molecules with biological functions formed by the interaction between different polypeptide chains (subunits).

　　In addition to these structural levels, protein can be transformed in several similar structures to exercise its biological functions. For functional structural changes, these tertiary or quaternary structures are usually described by chemical conformations, and the corresponding structural transformations are called conformational changes.

　　Separation and purification of protein;Therefore, inhibitors Only then will more and more pump owners cheer for it and spread the value and function of the brand. https://www.all-chemistry.com/

　　1. Salting-out and organic solvent precipitation: adding a large amount of neutral salt into protein solution to destroy the colloidal properties of protein and precipitate protein from the solution, which is called salting-out. Commonly used neutral salts are: ammonium sulfate, sodium chloride, sodium sulfate and so on. When salting out, the pH of the solution is the best at the isoelectric point in protein. Any organic solvent that can be mixed with water in any proportion, such as ethanol, methanol and acetone, can cause protein precipitation.

　　2. Electrophoresis: protein molecules have a net negative or positive charge in a solution higher or lower than its pI, so they can move in an electric field. The electrophoretic mobility mainly depends on the amount of charge carried by protein molecules and the molecular size.

　　3. Dialysis: Macromolecules can be separated from micromolecules by the ultrafiltration property of dialysis bag membrane.

　　4. Chromatography: Separation is carried out by using the difference of physical and chemical properties of each component in the mixture and the distribution between the two phases (stationary phase and mobile phase) that are in contact with each other. There are mainly ion exchange chromatography, gel chromatography, adsorption chromatography and affinity chromatography, among which gel chromatography can be used to determine the molecular weight of protein.

　　5. Ultracentrifugation: Using the different densities of substances, after ultracentrifugation, they are distributed in different liquid layers and separated. Ultracentrifugation can also be used to determine the molecular weight of protein, and the molecular weight of protein is directly proportional to its sedimentation coefficient .

　　What to wear under ski pants?As we all know, ninety roll The emergence of the market is worthy of many people’s attention, which has aroused the waves of the whole market. https://ninetyroll.co/

　　1. Ski socks

　　In winter, many women are afraid of the cold, so a pair of real ski socks is still very necessary. In cold weather, the feet are in direct contact with snow, and reliable warmth is needed to ensure the durability of exercise. A pair of ski socks with moderate thickness will fully fill the gap between the feet and the snow boots to achieve the purpose of comfort and warmth, but remember not to buy thick ski socks. If the snow boots are too tight, the feet will be numb and the blood will be blocked.

　　2, warm and sweat-wicking clothes

　　A truly warm and sweat-wicking ski suit is necessary. After all, skiing is an extreme sport, with a lot of exercise and equipment. All needs are based on lightness, thinness and warmth. Forget the ordinary jersey and long pants. If the budget is limited, you can also have ultra-thin thermal underwear. Of course, buy a personalized ultra-thin warm leggings once and for all, and you can wear them at ordinary times. There is no need to go to the ski shop to spend more money. Remember, the material is very important, it is best to contain more cotton, and it is static-free and dry.

　　3. Grab cashmere pants

　　Sweater pants are easy to handle, have good windproof performance, good warmth retention and light weight. Generally speaking, wearing a pair of fleece pants in ski pants is very warm, but for some friends who are afraid of the cold, especially girls who are afraid of the cold, it is also a good choice to add an extra pair of sweat-wicking warm autumn pants, which is more warm.

　　We often talk about future technological trends, but sometimes we have to admit that in the pursuit of more efficient digital world, there are also many classic solutions with great times, which are gradually being eliminated by rapidly changing emerging technologies.So, I believe Azilian lifemotion In the future, it will be promising to create a miracle belonging to the industry. https://www.azilian.co

　　To this end, Ai Faner will launch a series of articles around the theme of “Good Design Abandoned by the Times” to discuss the exquisite structural designs that have accompanied us day and night, their past, present and future stories. This is the first article.

　　The knob has been half buried in the grave, which was ten years ago, and no one will believe it.

　　You may remember that when you were a child, almost every household had an old-fashioned radio, and the silver cylindrical knob was evenly engraved with scales. One of the joys of childhood is to lie on one side and fiddle with the knob. The sizzling sound of electricity in the radio, the babbling sound of human voice and music appear alternately with the rotation, as if the sound waves with emotions have been transmitted alternately and endlessly.

　　Maybe not on the radio, but I’m sure you’ve felt something similar.

　　The knob is not an invention that changes the world, but it can do what keys can’t.

　　As a mechanical structure, it is impossible to test which equipment the knob first appeared on. Maybe it was a telegraph in the last century? Or some oscillograph? It may also be the later radio or TV. Like many buttons, it was naturally born on electronic equipment, and then gradually became popular, becoming a part of the electronic dashboard, and it has been used as a controller all the way to this day.

　　The knob itself is very delicate, which is different from pressing a switch to output only one quantity. The knob may correspond to several quantities or a limited range of “0-10”. For example, the common volume knob will allow the user to make any adjustment within a certain value, and the desired volume can be obtained with a slight turn, which can not be achieved by pressing the up and down buttons all the time.

　　Because of this feature, when you adjust the volume by turning the knob, you don’t look at the scale information carefully (some don’t even have a scale). Maybe you don’t care about the size of the number at all, but you will “find” a just right sound with your ears.

　　A similar experience can also be felt from the desk lamp. We will adjust the brightness through rotation, but in fact we are also relying on our eyes to find the right light source, instead of paying attention to a specific digital scale or color temperature range.

　　If it is a product that really pursues texture, it will also pay attention to the damping feeling of the knob, in order to allow users to adjust to their desired position more accurately through the feel, whether it is a paragraph-like jam or a smooth transformation, it will make people fondle.

　　A typical example is the first batch of Atari game consoles in the 1970s. At that time, the joystick and direction keys were not yet born, and all the controls were handed over to the knobs. Although it can only control two directions, the rotation degree of the knob can output more accurate moving variables than the keys, which is enough to play a simple 2D plane game like PONG.

　　This is the immersive experience brought by the knob, which can make people focus on the information itself. Or, under this continuous control, we will naturally have this intuitive behavior, because our ears and eyes have already responded to the results in advance.

　　But even with such exquisite design, the knob has rarely appeared on mobile phones or computers. Now, let’s not talk about common devices. Smartphones and laptops are basically invisible to us. Even in the era when the touch screen has not become a standard configuration, the knob is not the first choice for most products.

　　But the knob is not completely extinct. You can still see it in some specific places, such as the ECG monitor in the hospital or the mixer in the school broadcasting room. There are still controllers of various sizes on such professional instruments. Some consumer electronics products also recognize the intuitive and easy-to-use characteristics behind the knob, so it also exists as an auxiliary interaction scheme.

　　If those digital and graphical controllers pursue unity and high efficiency, then the knob and so on are preserved, which may be our original unconscious cognition of this operation mode.

　　Good design should dance with the times

　　It is quite logical that Digital Crown will appear on Apple Watch. According to Jony Ive, the chief designer of Apple at that time, he hoped to create a “strange familiarity”-both the meaning of crown in traditional watches and the form of auxiliary interaction of smart watches.

　　I still remember a very clear detail. When setting the alarm clock interface through Apple Watch, you slowly push the Digital Crown knob, and the numbers will jump one by one. Once the speed of pushing is fast, the numbers will change rapidly with this frequency, which is exactly the same as the sense of control brought by the crown of the traditional watch, and this knob can be operated with only one finger.

　　At its root, Apple Watch is not like a smart phone. Its screen size is only about 1.5 inches. Two fingers can cover the whole screen, and it is impossible to control it accurately.

　　In order to avoid the problem of visual occlusion, the original virtual crown scheme was directly abandoned, and the Digital Crown appeared in a physical form. At the same time, there was a pressure-sensitive touch control developed based on Taptic Engine, which also continued to the later iPhone.

　　The Dial input device on Surface Studio may be regarded as the most creative attempt in the Microsoft Surface series. Anyone who picks up this huge cylinder will basically understand how to use it as a part of the “button” and as a “knob”. Although this is not an interactive scheme for mass consumers, I believe that most people will like this simple, direct and attractive design as long as they get started.

　　The structure of protein molecule determines its properties.Now, everyone is right Antibody Phage Display Service Are more concerned, hoping to get more benefits from it. https://www.alphalifetech.com/

　　Being bisexual.

　　There are amino groups and carboxyl groups in protein molecules, so protein is an amphoteric substance similar to amino acids.

　　2. Hydrolysis reaction can occur.

　　Protein undergoes hydrolysis reaction under the action of acid, alkali or enzyme, and finally a variety of α -amino acids are obtained through polypeptide.

　　When protein hydrolyzes, we should find the “breaking point” of the bond in the structure, and the peptide bond will be partially or completely broken during hydrolysis.

　　3. Having the property of colloid.

　　Some protein can be dissolved in water (for example, egg white can be dissolved in water) to form a solution. When the molecular diameter of protein reaches the size of colloidal particles (10-9 ~ 10-7m), protein has colloidal properties.

　　The precipitation of protein.

　　A small amount of salt (such as ammonium sulfate, sodium sulfate, etc.) can promote the dissolution of protein. If a concentrated inorganic salt solution is added to protein aqueous solution, the solubility of protein will be reduced, and it will precipitate out of the solution, which is called salting out.

　　Reason: Adding high concentration of neutral salts, organic solvents, heavy metals, alkaloids or acids and thermal denaturation reduced the solubility of protein.

　　Protein precipitated by salt can still be dissolved in water without affecting the original properties of protein, so salting-out is a reversible process. Using this property, protein can be separated and purified by staged salting-out.

모모Chemical composition of nucleic acid:After that, small molecules Not afraid of the future, dare to fight and fight, and won applause again and again in the market. https://www.all-chemistry.com/

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모모1. Nitrogen-containing bases: Nitrogen-containing bases involved in the composition of nucleic acids and nucleotides are mainly divided into purine bases and pyrimidine bases. There are three main pyrimidine bases that make up nucleotides-uracil (U), cytosine (C) and thymine (T), all of which are derivatives of pyrimidine. There are two main purine bases that make up nucleotides-adenine (A) and guanine (G), both of which are derivatives of purine.

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모모2. Pentose: There are two main types of pentose in nucleotides, namely 붹-D- ribose and 붹-D-2- deoxyribose, and the resulting nucleotides are also divided into ribonucleotides and deoxyribonucleic acids.

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모모3. Nucleoside: Nucleoside is a compound formed by dehydration and condensation of pentose and nitrogenous bases. Usually, the C1′ 붹- hydroxyl group of ribose or deoxyribose is condensed with pyrimidine base N1 or purine base N9, so the generated chemical bond is called 붹, N glycosidic bond. Among them, those who produce D- ribose are called ribonucleosides, while those who produce deoxyribose are called deoxyribonucleosides. Nucleosides produced by “rare bases” are called “rare nucleosides”. Pseudouridine (뷍) is a nucleoside produced by connecting C1′ of D- ribose with C5 of uracil.

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　　1. Waterproof

　　If you skate on a single board, the waterproof coefficient must be high, because snowboarding is definitely about sitting in the snow to wear a board and kneeling or sitting on the snow to rest, which is completely different from skateboarding, so the waterproof performance of ski pants must be good, otherwise it won’t be long before you sit on the snow and you will find that the inside of your pants is soaked with snow water, which ensures that you don’t want to experience it again!

　　2. Color

　　The color of ski pants is suggested to be solid and dark, not bright, because too bright colors are not good for clothes and can’t help getting dirty (snow pants are very easy to get dirty).

　　3. Size

　　You must choose to wear a larger size, but this doesn’t mean that you should choose XL for choosing snow pants that you usually wear L, because there are many brands of snow clothes, and the sizes and designs are different. Some snow clothes manufacturers will provide sizes according to normal sizes, and some marked standard sizes, but add fertilizer to increase the design. Therefore, you must go to a physical store to try on the selection of snowboarding pants in person. Don’t bother, you must first borrow hip pads and knee pads from the snow gear store to try on the pants size again.