برزنتيشن انجليزي عن الماء قصير

 موضوع انجليزي عن الماء للصف الثامن فقرة  برزنتيشن بحث موضوع ملخص جاهز باللغة الانجليزية  انشاء موضوع انجليزي عن ابدا قصير كيفية كتابة موضوع تعبير باللغة الانجليزية توجيهي قواعد كتابة تعبير  بالانجليزي طريقة سهلة لكتابة تعبير بالانجليزي موضوع تعبير انجليزي يصلح لكل المواضيع كتابة تعبير بالانجليزي عن نفسك وصف تعبير انجليزي يصلح لكل المواضيع موضوع انشاء شامل لكل المواضيع موضوع يصلح لجميع المواضيع موضوع تعبير انجليزي جاهز برجراف ينفع لاى موضوع  موضوع انجليزي عن الماء تعبير عن الماء بالانجليزي قصير وسهل فوائد الماء بالانجليزي قصير بحث عن الماء  عبارات  بالانجليزي طويل فوائد الماء للجسم  قصير وسهل بحث انجليزي عن تلوث الماء  فوائد شرب الماء بالانجليزي اهمية الماء بالانجليزي مترجم تعبير عن الماء بالانجليزي ثالث ثانوي برزنتيشن عن الماء بالانجليزي  برزنتيشن عن الماء بالانجليزي قصير  عن المياه المياه المائية خمس سبع ثمان تسع اربع جمل كلمات كلام مقال علمي مقدمة

The importance of water in biological systems

Water has a number of basic properties that have no doubt played a role in the appearance and maintenance of life. The thermodynamic diagram of the states of water shows a zone of stability of the liquid well adapted to the conditions of temperature and pressure on the surface of the Earth. The lower density of the ice implies that it floats on the liquid; an important parameter to preserve life through climatic fluctuations. The hydrogen bond which characterizes the chemical properties of the molecule is well adapted to the bonds with the organic molecules and between the molecules of water themselves. It controls the hydrophilic and hydrophobic relations whose interplay allows a great variety of chemical situations. Water, whose dielectric constant is high, is a solvent for a large number of salts, but also gases such as oxygen. Within it can occur chemical reactions. The thermodynamic properties measured on the water sometimes give the impression that water is an "abnormal" liquid (compared to liquids formed from an assembly of hard spheres). This impression is due to the fact that many properties do not show a linear evolution with temperature and pressure due to the fluctuation of the number of hydrogen bonds between the water molecules. The "structure" of water, studied by many physical methods, is always the subject of sometimes heated controversy.

By its ability to corrosion against minerals, water had to play a vital role in the appearance of life (formation of sulfur-containing enzymes in particular). It still hosts "simple" forms, more or less well known, of "living" beings (like viruses in the oceans).

Hydrophobes are molecules whose solubility in liquid water is low, mainly because these molecules do not participate in the hydrogen bonding network of water. In this presentation, Bernard Cabane shows how the dissolution of apolar molecules in water is possible, and how it can be done without loss of hydrogen bonds. It presents in a second time two examples of large hydrophobic molecules whose solubility in water is very low, but which nevertheless have important biological functions. The first example relates to drug molecules whose solubility is limited by their ability to crystallize. In this case, one wonders if the production of these drugs in the form of nanoparticle dispersions, amorphous structure, would increase their bioavailability. The second example concerns the tannins that are produced by plants and are part of their defense system against aggressors such as molds or herbivores. In this case, we seek to understand how the presence of proline-rich proteins in the saliva of herbivores and humans avoids the antinutritional effects of tannins.