The lower hydrates RE(NCS) 3.mH2O(when RE = La, Ce, Pr, Nd, m = 4.5; when RE = Sm, Eu, Gd, Dy, Ho, Yb, Y, m = 3) were prepared by means of dehydration of corresponding higher hydrates RE(NCS) 3.nH2O (when RE = La, Ce, Pr, Nd, n = 7;when RE = Sm, Eu ..Gd, Dy, Ho, Yb, Y, n = 6).
The standard molar hydration enthalpies and formation enthalpies for the three hydrates were also accurately obtained with the values of (-76.41,-114.08 and-141.28 kJ·mol~-1 ) and (-1289.39,-1898.72 and-2497.58 kJ·mol~-1 ) respectively.
According to the mechanism of nucleophilic addition reaction of carbonyl compound and water, this paper discusses the relation between the form of carbonyl aqua compound as well as its stability and molecular structure of carbonyl compound. It is explained that the stability of carbonyl aqua compound mostly lies on the ups and downs of electronic cloud density on carbonyl carbonaceous atom and that the size of space volume of base group directly connects with the carbonyl group for carbonyl compound.
2,5-Bihydrazino-1,3,4-thiadiazole (2) was synthesized by condensation of 2,5-bimercapto-1,3,4-thiadiazole (1) with hydrazine hydrate, and compound 2 reacted with acyl chloride to give 2,5-biacylhydrazino-1,3,4-thiadiazole derivatives (3a-3e).
Gas hydrate is a recently-found new source of energy that mostly exists in marine sediments.
In recent years, we have conducted gas hydrate exploration in the South China Sea.
The Xisha trough, one of the promising target areas for gas hydrate, is located in the northern margin of the South China Sea, adjacent to several large oil and gas fields.
These geochemical anomalies are quite similar to those found in gas hydrate locations in the world such as the Blake Ridge and may be related to the formation and dissociation of gas hydrates.
Asexual, non-budding hydras were treated in the 1∶75000 solution of E 39 solubile (Bayer).
When male hydras were fed at 10°C, they produced both buds and testes simultaneously.
Gram-negative bacteria 4.5-5.5 μm in length and 1.2 μm in diameter are found in gastrodermal cells of three stains of freshwater green hydras,Hydra viridis (Ohio and Carolina from North America, Jubilee strain from England).
Green hydras harbor strain-specific numbers of chlorellae in these cells.
Vesicles, especially conspicuous in sexually mature green hydras, are probably produced upon extrusion from the cell.