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   1144篇
  免费   83篇
林业   25篇
农学   32篇
基础科学   2篇
  98篇
综合类   151篇
农作物   13篇
水产渔业   46篇
畜牧兽医   795篇
园艺   17篇
植物保护   48篇
  2021年   14篇
  2020年   14篇
  2019年   9篇
  2018年   17篇
  2017年   26篇
  2016年   38篇
  2015年   22篇
  2014年   24篇
  2013年   41篇
  2012年   34篇
  2011年   49篇
  2010年   34篇
  2009年   34篇
  2008年   56篇
  2007年   43篇
  2006年   48篇
  2005年   57篇
  2004年   45篇
  2003年   37篇
  2002年   43篇
  2001年   32篇
  2000年   47篇
  1999年   38篇
  1998年   22篇
  1997年   30篇
  1996年   23篇
  1995年   12篇
  1994年   11篇
  1993年   12篇
  1992年   18篇
  1991年   11篇
  1990年   11篇
  1989年   24篇
  1988年   21篇
  1987年   9篇
  1986年   18篇
  1985年   13篇
  1984年   6篇
  1983年   8篇
  1982年   7篇
  1979年   7篇
  1978年   7篇
  1974年   15篇
  1973年   6篇
  1972年   6篇
  1971年   7篇
  1969年   13篇
  1967年   8篇
  1947年   6篇
  1939年   5篇
排序方式: 共有1227条查询结果,搜索用时 15 毫秒
131.
Forty-six adult merino ewes were immunised against oestradiol-17 beta-6 carbomethyloxime:human serum albumin and 48 comparable ewes were used as controls in an experiment to study the effects of gonadotrophin releasing hormone (GnRH) on ovulatory responses after treatment with pregnant mare's serum gonadotrophin (PMSG). All the ewes were treated with progestogen sponges for 14 days and received 1500 iu PMSG on the 12th day. Twenty-four control and 24 immunised ewes received 25 micrograms GnRH 21.5 hours and 23 hours after the sponges were withdrawn. Plasma samples were collected between 17 and 50 hours after the sponges were withdrawn and assayed for luteinising hormone (LH). Immunisation reduced the proportion of ewes which ovulated and their rate of ovulation. Injection of GnRH increased the proportion of immunised ewes ovulating (P less than 0.0005) and their rate of ovulation (P less than 0.0001). More unovulated follicles were observed in immunised ewes regardless of GnRH treatment (P less than 0.0001). The rate of recovery of eggs was reduced after immunisation. Treatment with GnRH produced a surge of LH of equal magnitude in the control and immunised ewes although not as many immunised ewes ovulated.  相似文献   
132.
Continuous-flow centrifugation leukapheresis techniques were used to collect 300-ml volumes of leukocyte-rich plasma from 5 nonmedicated horses and from 5 corticosteroid-stimulated horses. White blood cell counts and differential counts were performed on the horses before (base line) and up to 48 hours after leukapheresis. Systemic administration of hydrocortisone increased numbers of total WBC and neutrophils and improved harvest of these cells. Nonmedicated horses had a mean yield of 3.38 X 10(10) leukocytes in the 300-ml volume. Stimulated horses yielded a mean of 6.88 X 10(10) leukocytes. After leukapheresis, WBC counts decreased a mean of 38% in nonstimulated horses and decreased a mean of 30% in stimulated horses. By 6 hours after leukapheresis, circulating WBC counts of horses in both groups had returned to preleukapheresis values. The relationship between neutrophil yield and the 4 variables (preleukapheresis WBC count, preleukapheresis neutrophil count, preleukapheresis lymphocyte count, and the PCV of the leukocyte-rich plasma) were examined, using simple (pair-wise) correlation and multiple linear regression. A significant positive correlation was found between neutrophil yield and preleukapheresis WBC and neutrophil counts. Because sodium citrate was used in the collection system to prevent extracorporeal blood coagulation, ionized and total serum calcium concentrations were monitored before and after leukapheresis. Although total serum calcium concentrations remained unchanged, ionized calcium concentrations decreased approximately 33% from base-line values during the 2-hour leukapheresis procedures. Occasional mild muscle fasciculations were the only adverse clinical signs of citrate toxicity exhibited by the horses.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
133.
134.
135.
136.
137.
The histological affinity pattern of Dolichos biflorus agglutinin (DBA) in kidneys from mice (NMRI, Balb/c, CBA) and rats (Wistar) fixed by perfusion with formalin, Bouin, or HgCl2 was investigated with a horseradish peroxidase conjugate. The animals were examined from fetal stage to adulthood. Adult female NMRI mice exhibited constant DBA labelling, with DBA binding to cells of the proximal and collecting tubules. Moreover the vascular endothelium of the renal papilla was found to be DBA-positive in 50% of adult female animals. In contrast, there was only very little DBA binding in the kidneys of male adult NMRI mice. There was no sexual dimorphism in lectin labelling in kidneys from other strains of mice or from rats.  相似文献   
138.
139.
The immune response of cattle and pigs to a vaccinia recombinant virus containing the fusion (F) protein gene of rinderpest virus was examined. Half the cattle and all the pigs gave humoral response to primary vaccination and all the cattle gave an anamnestic response to a second vaccination 28 days after the primary vaccination. All the cattle after a single or secondary vaccination were completely protected clinically after exposure to a lethal dose of the Saudi 1/81 strain of virus. Prior vaccination with another TK- vaccinia recombinant (VVCAT) suppressed, but did not abrogate, the immune response to the rinderpest F recombinant. The pigs gave a humoral immune response in the absence of any local reaction at the site of vaccination.  相似文献   
140.
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