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   338536篇
  免费   18223篇
  国内免费   708篇
林业   24877篇
农学   14290篇
基础科学   3031篇
  48750篇
综合类   48658篇
农作物   17467篇
水产渔业   18787篇
畜牧兽医   148266篇
园艺   6634篇
植物保护   26707篇
  2019年   3827篇
  2018年   4630篇
  2017年   5132篇
  2016年   5218篇
  2015年   4583篇
  2014年   5961篇
  2013年   16647篇
  2012年   8768篇
  2011年   11384篇
  2010年   8494篇
  2009年   8848篇
  2008年   10660篇
  2007年   9887篇
  2006年   10080篇
  2005年   9345篇
  2004年   9124篇
  2003年   8905篇
  2002年   8225篇
  2001年   9294篇
  2000年   8928篇
  1999年   7680篇
  1998年   4476篇
  1997年   4515篇
  1996年   4235篇
  1995年   4963篇
  1994年   4391篇
  1993年   4068篇
  1992年   6289篇
  1991年   6540篇
  1990年   6344篇
  1989年   6308篇
  1988年   5727篇
  1987年   5778篇
  1986年   5881篇
  1985年   5941篇
  1984年   5206篇
  1983年   4746篇
  1982年   3652篇
  1981年   3450篇
  1980年   3394篇
  1979年   4764篇
  1978年   4077篇
  1977年   3641篇
  1976年   3398篇
  1975年   3446篇
  1974年   4022篇
  1973年   4039篇
  1972年   3722篇
  1971年   3512篇
  1970年   3361篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
Since the International Society of Veterinary Acupuncture (IVAS) was founded in 1974, acupuncture (AP) has received greater acceptance by veterinary professionals throughout the world. This article introduces some important animal diseases that respond well to AP therapy. These include resuscitation of small animals, treatment of anoestrous gilts and sows, bovine reproductive disease, canine vertebral problems and equine backpain, etc. Conventional medicine considers these to be difficult cases to treat. Veterinarians have become more aware of the benefits of AP especially for those diseases, thanks to the efforts of experienced practitioners and scientists, and the many published reports on veterinary AP that have introduced some good indications for AP therapy in veterinary practice. Possible mechanisms behind the effectiveness of AP are discussed. This article aims to introduce veterinarians to good indications for AP to initiate their interest in the practice of AP. Although this is a rapidly expanding field, a long march must begin with one step. We wish this article to be the shoes for such a march. For more information on veterinary AP, contact IVAS , P.O. Box 1478, Longmont, CO.. 80502, USA (http://www.ivas.org), or your national veterinary acupuncture society (http://www.komvet.at/ ivadkom/vapsocs.htm).  相似文献   
132.
Two serological tests (indirect immunofluorescence and enzyme-linked immunosorbent assay) were developed for the detection of fetal antibody to Chlamydia psittaci. Fetal blood and thoracic fluid from 126 field cases of suspected ovine chlamydial abortion were examined using both tests. Placenta and fetal tissues (lung, liver, and kidney) from the same animals were also examined by the following conventional diagnostic methods: isolation in McCoy cells, detection of chlamydial lipopolysaccharide (LPS), modified Ziehl-Nielsen staining, and direct fluorescent antibody staining of chlamydia in frozen cryostat sections. Seventy cases were positive by fetal serology, and of these, 68 were also positive by isolation and/or LPS detection. The remaining 56 cases had negative fetal serology, and of these, 39 were positive by isolation and/or LPS detection. Results indicate that fetal serology, although less sensitive than either isolation in McCoy cells or detection of chlamydial LPS antigen, may be of particular use when placenta is not available.  相似文献   
133.
Subgroup-specific peptide-based enzyme-linked immunosorbent assays from the G-protein of the ovine and bovine respiratory syncytial virus (RSV), respectively, were used to determine the prevalence of the ovine and bovine subgroup strains of RSV infections in cattle. A total of 1,102 bovine serum samples were obtained from 6 diagnostic laboratories located in the northwestern and the southeastern USA and were tested for antibody to either the bovine or ovine subgroups of RSV. Antibody to viruses from each subgroup was present in samples from each region and all states tested. The Southeast had a higher prevalence of the bovine subgroup strains (69.5%). Then did the Northwest (40.9%). The prevalence of the ovine strain was similar for the two regions (16.7% in the southeast, 14.9% in the northwest). The overall prevalence was 56.6% for the bovine strain and 15.9% for the ovine strain. These results suggest members of the ovine subgroup of RSV circulate in the cattle population but with less frequency than those viruses of the bovine subgroup.  相似文献   
134.
135.
    
Ohne Zusammenfassung  相似文献   
136.
137.
138.
Ohne Zusammenfassung  相似文献   
139.
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