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   84705篇
  免费   7069篇
  国内免费   8665篇
林业   9465篇
农学   12965篇
基础科学   6964篇
  14048篇
综合类   24259篇
农作物   4257篇
水产渔业   4927篇
畜牧兽医   14383篇
园艺   3012篇
植物保护   6159篇
  2024年   188篇
  2023年   767篇
  2022年   2057篇
  2021年   3055篇
  2020年   3181篇
  2019年   3518篇
  2018年   2697篇
  2017年   3647篇
  2016年   3480篇
  2015年   4154篇
  2014年   4130篇
  2013年   5164篇
  2012年   5527篇
  2011年   5887篇
  2010年   5805篇
  2009年   4996篇
  2008年   4811篇
  2007年   5060篇
  2006年   4578篇
  2005年   4147篇
  2004年   2144篇
  2003年   1872篇
  2002年   1785篇
  2001年   1765篇
  2000年   1954篇
  1999年   1983篇
  1998年   1794篇
  1997年   1516篇
  1996年   1388篇
  1995年   1304篇
  1994年   1152篇
  1993年   1087篇
  1992年   894篇
  1991年   722篇
  1990年   635篇
  1989年   455篇
  1988年   372篇
  1987年   267篇
  1986年   145篇
  1985年   61篇
  1984年   53篇
  1983年   54篇
  1982年   41篇
  1981年   52篇
  1980年   27篇
  1979年   12篇
  1978年   10篇
  1977年   6篇
  1974年   5篇
  1962年   5篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
961.
962.
963.
The aim of this study was to investigate the variability of the internal pudendal artery. Two hundred and thirty‐two pelvic halves from 116 adult dogs were examined. Twenty‐six anatomical variations were found, thirteen occurring in more than 5% of the dogs. Anatomical variations were grouped in relation to the origin of the prostatic/vaginal arteries, middle rectal artery, urethral artery, ventral perineal and caudal rectal arteries. The chi‐squared test was used to analyse differences in sex, side of the body, profile and size, and the results were considered statistically significant when  0.05. An identical vascular pattern in both hemipelvises was found for most of the anatomical variations described.  相似文献   
964.
The aim of this study was to analyse and describe the variability of the umbilical artery. Two hundred and thirty‐two pelvic halves from 116 adult dogs were examined. To study the permeability of the umbilical artery, ten adult dogs, nine newborns and thirteen foetuses between 35 and 50 days of gestation were also used. In relation to the origin of the umbilical artery, six anatomical variations were found. From which five involved a cranial (= 4) or caudal (= 1) relocation of its origin, and in one case (= 1), the umbilical artery arose from the median sacral artery. In eight cases, the umbilical artery gave off the prostatic (= 1) or vaginal (= 7) arteries. The permeability of the umbilical artery was the most significant anatomical variation: permeability was detected in 45% (106 of 232 pelvic halves) of all cases, from which 36 were males and 70 females. Interestingly, an equal vascular permeability in both hemipelvises was found for 82% of the dogs, thus additional data related to such feature of the umbilical artery was also recorded. In accordance with the statistical study, the main anatomical variations described showed significant values for gender, side of the body, size and profile variables.  相似文献   
965.
This study aims to enhance the anatomical knowledge of the ear of the adult quail (Coturnix coturnix) through the creation of a scaled 3D model utilizing data from micro‐CT images. In addition, 17 annotated histological sections of the quail's ear are aligned to their 3D position in the model. The resulting anatomical atlas provides an intuitive insight into the 3D anatomy and can be used for medical education. The model also allows measuring anatomical structures and can thus serve as reference for the quail's auricular anatomy and as a basis to evaluate clinical diagnostic imaging results.  相似文献   
966.
967.
A 5.5‐year‐old, intact male Rottweiler dog was admitted with a history of multifocal nodular tongue lesions which progressively deteriorated during the previous year. Physical examination revealed several reddish nodules with central depression on the surface of the tongue in an otherwise healthy dog. Clinicopathologic abnormalities included eosinophilia and hyperproteinemia. Lingual nodule cytopathology, histopathology, and immunohistochemistry revealed Leishmania spp. amastigotes and a severe granulomatous glossitis. The dog was also seroreactive to L infantum antigens by an indirect immunofluorescence assay. Clinical reevaluation 3 months after the institution of treatment with allopurinol and miltefosine indicated that the nodular lesions had completely regressed. In endemic areas, lingual nodular lesions may rarely be the sole clinical sign of canine leishmaniosis. Standard medical treatment may provide an excellent prognosis.  相似文献   
968.
969.
970.
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