首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   635篇
  免费   47篇
  国内免费   1篇
林业   27篇
农学   23篇
基础科学   8篇
  83篇
综合类   86篇
农作物   54篇
水产渔业   68篇
畜牧兽医   242篇
园艺   15篇
植物保护   77篇
  2022年   10篇
  2021年   9篇
  2020年   7篇
  2019年   22篇
  2018年   15篇
  2017年   16篇
  2016年   25篇
  2015年   18篇
  2014年   10篇
  2013年   36篇
  2012年   52篇
  2011年   56篇
  2010年   29篇
  2009年   36篇
  2008年   45篇
  2007年   43篇
  2006年   42篇
  2005年   28篇
  2004年   31篇
  2003年   24篇
  2002年   21篇
  2001年   9篇
  2000年   8篇
  1999年   7篇
  1998年   2篇
  1997年   5篇
  1996年   3篇
  1995年   3篇
  1994年   5篇
  1993年   9篇
  1992年   7篇
  1991年   9篇
  1990年   3篇
  1988年   3篇
  1987年   6篇
  1985年   3篇
  1984年   2篇
  1983年   1篇
  1982年   4篇
  1980年   2篇
  1979年   3篇
  1978年   1篇
  1977年   1篇
  1976年   2篇
  1974年   1篇
  1972年   2篇
  1970年   1篇
  1969年   2篇
  1960年   1篇
  1930年   1篇
排序方式: 共有683条查询结果,搜索用时 15 毫秒
681.
The distribution and kinetics of lactate dehydrogenase (LDH) isozymes in the red and white trunk muscles, and cardiac muscle of an antarctic teleost fish (Notothenia neglecta Nybelin) have been studied. Pyruvate inhibition of LDH in all three muscle types is very low, being less than 50% even at a concentration of 60mM pyruvate. Activity versus pyruvate concentration profiles are not significantly different for LDH in all three muscle types. The Michaelis constant (Km) for pyruvate was not significantly different for all three LDH's. Raising the assay temperature caused an increase in Km of similar form in all three muscle types, while Km was lowest at the lowest assay temperature (–1°C). When samples were run on a polyacrylamide gel, the bands stained specifically for LDH activity appeared at identical positions as those of the H2M2 band of the standards.It would appear therefore that the LDH isozyme found in the red and white trunk muscle ofN. neglecta is identical to that in cardiac muscle. This fact is discussed in relation to the physiological ecology of antaretic fishes, and the metabolic constraints imposed by their habitat, including their apparent low capacity for utilising glycolytic fuels.  相似文献   
682.
The present study was conducted to explore the potential to incorporate local plant-based feed ingredients into diets formulated for the mud crab species, Scylla paramamosain , commonly exploited for aquaculture in South-east Asia. Four test ingredients (defatted soybean meal, rice bran, cassava meal and corn flour) were incorporated at 30% or 45% inclusion levels in a fishmeal-based reference diet and used in digestibility trials where apparent digestibility coefficients (ADCs) for experimental diets and test ingredients were determined. Generally, high ADC values were obtained using diets containing 30% soybean meal or rice bran. By contrast, the lowest ADC values were obtained for the diet containing 45% cassava meal [70.9% for dry matter (ADMD); 77.1% for crude protein (ACPD) and 80.2% for gross energy (AGED)]. Similar trends were observed when ADC ingredient (I) digestibilities were compared. Specifically, the highest ADCI values were obtained for soybean meal when used at a 30% inclusion level (87.6% ADMDI; 98.4% ACPDI and 95.6% AGEDI) while the lowest ADCI values were obtained using cassava meal at a 45% inclusion level (53.8% ADMDI; 60.2% ACPDI and 67.3% AGEDI). Based on the current findings, we propose that soybean meal and rice bran could be considered for incorporation into formulated diets for S. paramamosain .  相似文献   
683.
The white grouper is a desirable aquaculture species that adapts to captivity, grows well and commands a high market price. However, little is known about reproductive biology or control of sex reversal of this protogynous hermaphrodite. In this study, female white groupers were implanted with one dose of 17α‐methyltestosterone (10 mg/kg body weight [BW], MT) and two doses of aromatase inhibitor, fadrozole (1 and 3 mg/kg BW, FD1 and FD3) once a month for 4 months (April–July). At the start of the study, the fish had gonads full of oocytes compared to the end of the experiment when the control group mature oocytes compared to the experimental groups MT, FD1 and FD3 that exhibited different stages of testicular tissue. Plasma levels of testosterone were significantly highest in the FD3 group and the highest 11‐Ketotestosterone levels were observed in the MT group. Plasma levels of oestradiol (E2) were significantly lower in the FD implanted groups, compared to initial individuals and control groups. The use of aromatase inhibitor, FD for sex reversal both gives further insight into the mechanisms controlling sex differentiation and provides an alternative to steroid treatment.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号