Abstract:This paper reported that Bellamya purificate was highly sensitive to environmental factors. The growth speed and spawning number would increase when the water temperature raised. The experiment showed that Bellamya purthcate could live normally when pH value was 4.0~9. 4, but the optimum value was 6. 0~7. 8. Bellamya purificate has strong ability to anti-dry. Only the losing ratio of water is over 30% would cause to die.When the total nitrogen content is over 5.53%, it will find nothing of Bellamya purificate,but they can live normally when the total nitrogen content is not higher than 3. 6%. Bellamya purificate can live in high polluted and middle polluted water regions.

Abstract:The protein requirement of young grey mullet, Mugil cephalus, was studied by using three diets containing 24%, 28% and 32% protein for eight weeks. The results showed that average weight gain and special growth rates(SGR) of the diet of 28% protein were both the highest. The protein content of the diets had no effects on the muscle composition of the fish. Four diets with protein to energy (P:E) ratios of 86. 2, 90. 3, 94.9 and 100. 0 mg protein/kCal energy were fed to groups of grey mullet for a period of six weeks.Average weight gains were 32. 5, 34. 2, 31. 3 and 23.8 g/ind respectively, and the SGR were 0. 70, 0. 79, 0. 74 and 0. 60 respectively. Composition of muscle was no significance affected by dietary P to E ratio. However, protein content of whole body decreased and lipid content increased at low P to E ratios. The optimum P to E ratio for grey mullet was determined to be 91mg/kCal, based on high weight gain and low lipid deposition in the abdominal cavity.

Abstract:With the development of large-mouth bass, Micropterus salmoides cultivation, artificial feed have become the key of increasing feed efficiency. The objective of this study is to determine the effects of dietary protein, fibre and fat on the growth of large-mouth bass. Accornding to orthogonalty trial Table L9(34), using casein, cellulose and soybean oil, the feeding tests were carried out for 23-29g young fish. The content of components was designed 3 levels: protein of 39%, 42%, 45%; fiber of 2. 5%, 3. 5%,4. 5%; fat of 5%, 6% and 7%. The results show that protein and fiber had signficant differences on weight gain among their levels (P<0. 05), i. e., 42% and 45% protein were better than 39%; 2. 5% and 3. 5% fiber were better than 4. 5%. Protein efficiency ratio apparent digestibility and food coefficient ratio showed further that 42% protein and 2. 5 % fiber were the best. There was no difference on weight gain and protein efficiency ratio among fat levels (P>0. 1), 5%-7% fat is also the suitable content. Thus the large-mouth bass's best compounded diet suggested is 42% protein, 2. 5 % fiber and 6% fat.

Abstract:本文讨论如上形式的二阶微分方程ｙ″（ｘ）＋Ｐ（ｘ）ｙ′（ｘ）＋Ｑ（ｘ）ｙ（ｘ）＝Ｒ（ｘ），０〈ｘ〈１，ｙ′（０）＝Ａ，ｙ（１）＝Ｂ其中Ａ，Ｂ为常数，系数Ｐ（ｘ），Ｑ（ｘ）在ｘ＝０处有奇性，考虑到系数为ｘ＝０处有奇性，无法用一般差分格式进行计算，故将区间（０，１〕划分在（０，δ〕（δ靠近奇点）。在（０，δ〕）区间寻求级数形式的银，继而确定ｙ（δ）值，在〔δ，１）区间上用离散不变嵌入法寻求该问题的差分

Abstract:This paper describes that GCHV-892 has been domesticated continuously for 19 generations in cell 1ine (PSF) in culture solution with certain concentration of liquid being from An (Eucalyptus) leaves, and has been attenuated. Effect of attenuation has been stabilized for continuous domestication from 19 to 29 gen. The effect of attenuation has still been stabilized for continuous domestication up to 37 gen. After the An liquid did not add to the culture solution from 27~37 gen., there are good innocuity and strong immunogenicity of virus for grass carp. Attenuated live vaccine prepared with the attenuated strain for grass carp is 100% in innocuity survival rate and immune protection rate. It shows that the An liquid is a good attenuated medicine for virus of hemorrhage of grass carp, and GCHAV-892 attenuated with An liquid is a good attenuated strain.

Abstract:Reliability designology can deal with the failure probability under working conditions of machine products and therefore compensate for the shortcomings of traditional method. The reliability design of the spindle of the hydraulic winch is discussed in this paper. Case study shows that the diameter of the critical cross-section can be reduced from 200mm to 160mm, and that the reliability design possesses even more economy and safety than that of traditional method.