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   1396篇
  免费   53篇
  国内免费   5篇
林业   110篇
农学   75篇
基础科学   18篇
  281篇
综合类   100篇
农作物   137篇
水产渔业   132篇
畜牧兽医   434篇
园艺   31篇
植物保护   136篇
  2023年   16篇
  2022年   34篇
  2021年   66篇
  2020年   81篇
  2019年   66篇
  2018年   62篇
  2017年   60篇
  2016年   55篇
  2015年   58篇
  2014年   65篇
  2013年   121篇
  2012年   91篇
  2011年   103篇
  2010年   60篇
  2009年   32篇
  2008年   60篇
  2007年   58篇
  2006年   39篇
  2005年   31篇
  2004年   33篇
  2003年   28篇
  2002年   26篇
  2001年   12篇
  2000年   11篇
  1999年   11篇
  1997年   7篇
  1996年   9篇
  1995年   5篇
  1994年   6篇
  1993年   6篇
  1991年   11篇
  1990年   7篇
  1989年   13篇
  1988年   8篇
  1987年   9篇
  1986年   6篇
  1985年   9篇
  1984年   6篇
  1983年   6篇
  1981年   6篇
  1979年   5篇
  1978年   3篇
  1976年   4篇
  1975年   7篇
  1973年   4篇
  1972年   4篇
  1971年   6篇
  1970年   5篇
  1969年   4篇
  1966年   3篇
排序方式: 共有1454条查询结果,搜索用时 218 毫秒
101.
102.
Male and female Japanese quail (Coturnix coturnix japonica) were given intraperitoneal injections of [14C]DDT in ethanol at a rate of 13.4 mg/kg body wt. Fifty-six days later the tissues and droppings were analysed for total 14C and metabolites. The rate of loss of 14C in droppings was very similar in males and females. The maximal rate was reached on the third day, and 65–66% of the injected dose was voided by the fifty-sixth day. Ninety-three to ninety-four percent of the 14C in droppings and 83–90% of the 14C in tissues were extracted by solvents. Combined extracts from males and females were used for determination of DDT and its metabolites. Expressing all results as percentages of injected dose, the following were isolated from droppings: DDA (24%), DDT (3%), DDD (5.1%), DDE (11%), and uncharacterised polar metabolites (17%). Twenty-five percent of the dose was retained in the tissues and this was largely accounted for as DDT (10.4%) and DDE (10.5%). Of the total metabolites found 31% was DDE (almost equally divided between tissues and droppings) and 35% was DDA (almost entirely in droppings). Since DDD was not found in significant quantities in tissues, the substantial quantities in droppings were probably produced from DDT by the action of microorganisms.  相似文献   
103.
Despite the intensive management and husbandry precautions, exotic pregnant heifers imported to the Gezira, Sudan, suffered excessive stress. Four of five heifers aborted due to stress. Death was due to pasteurellosis, babesiosis and heart water.  相似文献   
104.
105.
Contents: The onset and progression of goat fetal skeletal radio opacity were studied to identify the stage of pregnancy and the number of fetuses present. Lateral radiographs using 75 KVP, 200 Ma, 0.25 s and 100 FFD was found to be good values for detection of pregnancy in goats. Lengths taken for skull, femur and vertebral column of the fetus were used as a parameter for determination of the stage of pregnancy. Counting the number of fetal skulls were used for estimating the number of fetuses present. Accurate radiological diagnosis of pregnancy in goat was possible after 10 weeks of gestation .
Inhalt: Radiographische Bestimmung der Trächtigkeit bei der Ziege
Der Beginn und die Weiterentwicktung fötater Skelettbildung wurde radiologisch bestimmt, um das Stadium der Trächtigkeit und die Zahl der Föten zu ermitteln. Laterale Röntgenbilder wurden mit 75 KVP, 200 Ma., 0,25 Sek. und 100 FFD ermittelt, wobei sich diese Einstellung als günstig für die Trächtigkeitserkennung bei Ziegen erwies. Die Ermittlung der Schädellänge, des Femurs und des Rückenmarks beim Fötus wurden als Parameter für die Bestimmung des Trächtigkeitsstadiums benutzt. Die Zahl der Fötalschädel ergab die Zahl der Föten. Genaue radiologische Diagnose der Trächtigkeit bei Ziegen war ab etwa 10 Wochen der Trächtigkeit möglich .  相似文献   
106.
Extracellular products in culture filtrates of Aeromonas salmonicida subsp. achromogenes and Vibrio anguillarum isolated from infected fish have been shown to possess skin inflammatory factor. The extracellular products from Vibrio anguillarum were cytotoxic in HeLa and CHO cells. In addition to the skin lesions, the culture filtrates of V. anguillarum caused necrotic reaction on the rabbit skin. Five of 6 strains of V. anguillarum were lethal to mice after intraperitoneal administration of 3×107 CFU. Only 1 strain of 5 A. salmonicida subsp. achromogenes produced extracellular products which elicited cytotoxic effects in the CHO cells. None of the A. salmonicida subsp. achromogenes strains were lethal to mice. The cytotoxins were inactivated when heated at 65°C for 30 min. The results indicate that the thermolabile exotoxins are non-enterotoxic since they failed to stimulate fluid accumulation in the rabbit ileal loop and did not cause elongation of the CHO cells. The rounding off of CHO cells, as well as of HeLa cells indicate that the exotoxins may play an important role in fish diseases.  相似文献   
107.
108.
Gross anatomical examination of the organization of the maxillary artery was carried out in 10 formalin embalmed, latex injected adult donkeys. The results indicate that although there are variations from other domestic animals, the distribution of this artery in the donkey is similar to that of the horse.  相似文献   
109.
110.
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