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   96784篇
  免费   5744篇
  国内免费   42篇
林业   3812篇
农学   3072篇
基础科学   573篇
  11916篇
综合类   16470篇
农作物   4024篇
水产渔业   5138篇
畜牧兽医   49758篇
园艺   1239篇
植物保护   6568篇
  2020年   804篇
  2019年   941篇
  2018年   1566篇
  2017年   1780篇
  2016年   1679篇
  2015年   1442篇
  2014年   1738篇
  2013年   3987篇
  2012年   3184篇
  2011年   3596篇
  2010年   2287篇
  2009年   2243篇
  2008年   3381篇
  2007年   3224篇
  2006年   3018篇
  2005年   2899篇
  2004年   2683篇
  2003年   2721篇
  2002年   2520篇
  2001年   3101篇
  2000年   2977篇
  1999年   2427篇
  1998年   1014篇
  1997年   928篇
  1996年   831篇
  1995年   982篇
  1994年   887篇
  1993年   881篇
  1992年   1939篇
  1991年   1916篇
  1990年   1853篇
  1989年   1937篇
  1988年   1681篇
  1987年   1794篇
  1986年   1846篇
  1985年   1767篇
  1984年   1392篇
  1983年   1240篇
  1982年   886篇
  1979年   1210篇
  1978年   992篇
  1977年   864篇
  1976年   786篇
  1975年   856篇
  1974年   1097篇
  1973年   1110篇
  1972年   1084篇
  1971年   1030篇
  1970年   911篇
  1969年   843篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Mast cell phagocytosis of red blood cells in a cat   总被引:1,自引:0,他引:1  
  相似文献   
992.
993.
994.
The hemorrhagic tendencies of 23 Doberman Pinscher pups were observed during cosmetic otoplasty and were ranked by a +1 to +4 grading system (+1 = least hemorrhage, and +4 = most hemorrhage). A second estimate of the hemostatic competencies of these dogs was made by counting the gauze sponges used in the otoplasties. Factor VIII-related antigen concentrations and coagglutinin cofactor concentrations were measured in plasma samples from blood drawn not more than 30 hours before the surgical procedures were done. The factor VIII-related antigen concentrations were between 9% and 147% of the concentration in a normal plasma pool, and the coagglutinin cofactor concentrations were between 1% and 165%, indicating that some of these dogs had von Willebrand's disease. The hemorrhagic tendencies of 12 pups were graded +1. This group had a mean antigen concentration of 75% (min-max, 38% to 147%) and a mean coagglutinin cofactor concentration of 89% (min-max, 42% to 165%). These were significantly greater than the antigen and cofactor concentrations of the grades +2 (n = 5), +3 (n = 3), or +4 (n = 3) dogs. Significant differences were not found when antigen concentrations of the grade +2 dogs (mean, 16%; min-max, 11% to 22%), grade +3 dogs (mean, 13%; 12% to 16%), and grade +4 dogs (mean, 11%; 9% to 12%) were compared with each other, nor were significant differences seen among the coagglutinin cofactor concentrations of the grade +2 dogs (mean, 7%; min-max, 1% to 11%), grade +3 dogs (mean, 6%, 4% to 8%), and grade +4 dogs (mean, 5%; 2% to 9%).(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
995.
Serum concentration was found to affect both the initial adherence and subsequent in vitro maturation of bovine monocytes. Bovine monocytes cultured in the absence of serum remained small and reduced in number, whereas monocytes cultured in an adequate concentration of either autologous adult bovine or fetal bovine serum developed into large macrophage-like cells. Heat inactivation (56 degrees C for 30 minutes) did not affect the ability of bovine sera to promote monocyte maturation in vitro.  相似文献   
996.
BCG treatment of periocular sarcoid   总被引:2,自引:0,他引:2  
Twenty-six horses and five mules with periocular sarcoids were treated with intralesional injections of a purified bacillus of Calmette and Guerin (BCG) cell walls in oil suspension. All sarcoids were cured and the horses and mules remained free from recurrence of sarcoid during the two-year follow-up period.  相似文献   
997.
Surgical treatment of hepatic and biliary disease requires a thorough knowledge of pertinent anatomy and pathophysiology. Proper attention to both preoperative and postoperative care is important. This article describes many of the more common surgical manipulations of the liver and biliary tract, as well as pre- and postoperative considerations.  相似文献   
998.
A technique for rapidly separating platelets from small quantities of whole blood is described. The isolation method allowed for counting and sizing platelets by electronic means, and counts with this new method were closely correlated with those obtained by phase microscopy. Platelet sizing was possible because of the inert and isotonic nature of the density-gradient medium used in the procedure. The technique was applicable to samples of blood from persons, horses, cattle, sheep, goats, pigs, dogs, mice, rats, guinea pigs, and rabbits. The isolation of platelets from whole blood of various species of animals was necessary for electronic counting because of the great variation in sizes of platelets and erythrocytes and the variable sedimentation properties of animal blood.  相似文献   
999.
Bovine mycotic abortion in some counties of the Irish provinces of Leinster and Ulster was estimated at 1–2% of all abortions for which a causal agent was identified in the years from 1969 to 1978. The organism most commonly isolated from diseased specimens wasAspergillus fumigatus, followed byAbsidia corymbifera. There was no relationship between the incidence of the disease in any year and the rainfall or number of raindays during the previous summer. The data obtained are discussed in relation to the occurrence of the disease in the United Kingdom.  相似文献   
1000.
The pathogenesis of canine parvovirus-2 was studied in orally inoculated conventional dogs using histopathological and peroxidase anti-peroxidase staining techniques. Lymphoid necrosis and depletion of lymphocytes from lymphoid tissues were most notable on days 5 and 6 after exposure. Lymphocyte hyperplasia occurred following day 7. Epithelial cell changes in segments of the small intestine were more severe on days 6 to 9 after exposure in areas associated with Peyer's patches and in the upper segments of the small intestine. The lymphocyte was the primary infected cell. Virus infected cryptal epithelial cells were not detected until 24 hours after the identification of infected cells in lymphoid tissues on day 4 after exposure. The majority of virus infected epithelial cells were found in crypts intimately associated with or adjacent to Peyer's patches in the upper segments of the small intestine.  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