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   11698篇
  免费   868篇
  国内免费   4篇
林业   1108篇
农学   507篇
基础科学   72篇
  3003篇
综合类   391篇
农作物   596篇
水产渔业   1241篇
畜牧兽医   4400篇
园艺   204篇
植物保护   1048篇
  2024年   19篇
  2023年   98篇
  2022年   151篇
  2021年   292篇
  2020年   287篇
  2019年   217篇
  2018年   597篇
  2017年   592篇
  2016年   580篇
  2015年   431篇
  2014年   515篇
  2013年   790篇
  2012年   920篇
  2011年   828篇
  2010年   494篇
  2009年   402篇
  2008年   684篇
  2007年   678篇
  2006年   542篇
  2005年   530篇
  2004年   452篇
  2003年   405篇
  2002年   334篇
  2001年   253篇
  2000年   231篇
  1999年   196篇
  1998年   42篇
  1997年   44篇
  1996年   39篇
  1995年   31篇
  1994年   24篇
  1993年   24篇
  1992年   61篇
  1991年   47篇
  1990年   41篇
  1989年   50篇
  1988年   39篇
  1987年   48篇
  1986年   48篇
  1985年   52篇
  1984年   39篇
  1983年   39篇
  1982年   20篇
  1979年   36篇
  1978年   35篇
  1977年   28篇
  1974年   27篇
  1973年   45篇
  1972年   33篇
  1971年   30篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
Canine transmissible venereal tumour (CTVT) is a contagious venereal tumour of dogs, commonly observed in dogs that are in close contact with one another, or in stray and wild dogs that exhibit unrestrained sexual activity. CTVT represents a unique, naturally transmissible, contagious tumour, where the mutated tumour cell itself is the causative agent and perpetuates as a parasitic allograft in the host. Clinical history, signalment and cytological features are often obvious for establishing a diagnosis though biopsy and histological examination may be needed in atypical cases. Most cases are curable with three intravenous injections of vincristine sulphate at weekly intervals. The role of stray and wild dogs makes the disease difficult to control and necessitates sustained animal birth control in stray dogs along with prompt therapy of the affected dogs. This review captures the manifold developments in different areas embracing this fascinating tumour, including its biology, diagnosis and therapeutic alternatives.  相似文献   
73.
74.
75.
76.
77.
78.
79.
80.
  1. The aim of this work was to improve natural anti-predator behaviour of farm-reared gamebirds.

  2. We evaluated the anti-predator behaviour of reared red-legged partridge Alectoris rufa chicks kept in brooder houses in large groups (>350 chicks), trained and not trained by parent red-legged partridges acting as experienced tutors.

  3. The experiment consisted of two conditioned tests (a raptor model and a human) and two control tests, which were conducted during three consecutive phases of life (1–4, 15–17 and 30–32 d after hatching). The motor anti-predator behaviour, its duration, the intensity of response in chicks and alarm calls elicited by adults were recorded.

  4. Tutors elicited aerial alarm calls (76% of tests) and showed prolonged crouching (59% of tests) in response to the raptor model whereas uttering the ground alarm call (73% of tests) and showing vigilance behaviour (78% of tests) was the main pattern during the human test.

  5. Trained and not trained chicks showed similar motor behaviour in response to the raptor model (crouching) and the human test (escaping), but frequency of strong responses (all chicks responding) from chicks trained with tutors was double that of chicks trained without them, and chicks trained with tutors showed a higher frequency of long responses (41–60 s).

  6. This study indicates that anti-predator training programmes before release may improve behaviour of farm-reared partridges which may confer benefits to survival of birds.

  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