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   172219篇
  免费   9263篇
  国内免费   673篇
林业   7931篇
农学   5525篇
基础科学   1351篇
  21111篇
综合类   34102篇
农作物   6918篇
水产渔业   7830篇
畜牧兽医   84169篇
园艺   2655篇
植物保护   10563篇
  2019年   1556篇
  2018年   3144篇
  2017年   3445篇
  2016年   2695篇
  2015年   2182篇
  2014年   2397篇
  2013年   6144篇
  2012年   5012篇
  2011年   6636篇
  2010年   4854篇
  2009年   4543篇
  2008年   6123篇
  2007年   5972篇
  2006年   4801篇
  2005年   4654篇
  2004年   4465篇
  2003年   4454篇
  2002年   4260篇
  2001年   4975篇
  2000年   4975篇
  1999年   3755篇
  1998年   1639篇
  1997年   1605篇
  1995年   1792篇
  1994年   1640篇
  1993年   1607篇
  1992年   3341篇
  1991年   3615篇
  1990年   3473篇
  1989年   3542篇
  1988年   3264篇
  1987年   3336篇
  1986年   3531篇
  1985年   3316篇
  1984年   2742篇
  1983年   2471篇
  1982年   1654篇
  1981年   1573篇
  1979年   2510篇
  1978年   2016篇
  1977年   1679篇
  1976年   1672篇
  1975年   1712篇
  1974年   2228篇
  1973年   2301篇
  1972年   2246篇
  1971年   2112篇
  1970年   1985篇
  1969年   1845篇
  1967年   1620篇
排序方式: 共有10000条查询结果,搜索用时 140 毫秒
991.
992.
993.
Two cases of noninfectious, nonerosive arthritis are presented. The diagnostic features, clinical course and treatment are reviewed. Potential etiologies are discussed in the light of relatively little current material on this subject in the veterinary literature.  相似文献   
994.
Pemphigus and pemphigoid are uncommon dermatological entities in domestic animals and of a presumed autoimmune nature. In one form or another, they have been reported in the dog, cat, horse and goat. Although these diseases are considered to be bullous dermatoses, the clinical presentation may vary from ulcerative to exfoliative to proliferative depending on the individual condition. Currently, four variants of pemphigus are recognized (vulgaris, vegetans, foliaceus, erythematosus) and two of pemphigoid (bullous, cicatricial) although cicatricial pemphigoid has not yet been conclusively demonstrated in animals. Diagnosis is based on history, clinical signs, histopathology and immunopathology. Therapy must be immunosuppressive to be effective and is palliative rather than curative.  相似文献   
995.
Reference ranges for five parameters of blood coagulation were established in clinically normal farmed fallow deer (Dama dama) and red deer (Cervus elaphus). Storage of plasma at -15 degrees C resulted in small increases in activated partial thromboplastin time (APTT) for both species, and in the one stage prothrombin time (OSPT) of fallow deer, between days 1 and 30. These times were then stable between days 30 and 60. The fibrinogen levels of fallow deer plasma showed a small apparent increase over 60 days. These storage artefacts were not of sufficient magnitude to preclude the use of such plasma for diagnostic purposes although they could limit its use in research. Levels of fibrin/fibrinogen degradation products (FDP) were not affected by storage at -15 degrees C. Rabbit brain thromboplastin appeared adequate for OSPT determination in both species. The activated clotting time (ACT) is recommended as a field test for screening the intrinsic and common pathways of blood coagulation in deer.  相似文献   
996.
997.
998.
An endoscopic survey was performed to assess arytenoid cartilage movement during quiet respiration in 48 Clydesdale horses. Physical characteristics which could influence the length of the recurrent laryngeal nerves were also recorded from these horses and the relationship of these characteristics to the presence of abnormal left arytenoid cartilage movements was assessed statistically. Some degree of abnormal arytenoid movement was observed in 50% of the animals over one year of age. No significant correlation between sex, age, estimated weight, height, or neck length could be found although affected animals were, on average, slightly taller, lighter and longer necked.  相似文献   
999.
A transitional cell carcinoma of the urinary bladder was found in a beluga whale stranded in the St. Lawrence middle estuary. Various organs of this animal were submitted to high resolution gas chromatography coupled with mass spectrometry analysis. High frequency of urinary bladder cancer in the human population of the same area and the presence of carcinogenic compounds in the marine environment of this animal are discussed.

Concurrent isolation of Edwardsiella tarda from various organs of this whale is also reported.

  相似文献   
1000.
1. Automatic weighing equipment was tested on a flock of 752 roaster chickens reared on litter to 10 weeks of age.

2. Mean body weights obtained automatically were lower than those obtained manually, mainly because of birds perching on the automatic weighing perch with part of their body in contact with the floor.

3. Birds observed on the weighing perch on one day of the week were 3–5 times more likely to use the perch again on the following 2 d than expected on the basis of random perch use by flock members. These birds were also more likely to be seen in the area immediately surrounding the perch than in similar areas elsewhere in the pen.  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