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   127752篇
  免费   6377篇
  国内免费   59篇
林业   5141篇
农学   3667篇
基础科学   856篇
  15389篇
综合类   23696篇
农作物   5137篇
水产渔业   5484篇
畜牧兽医   65876篇
园艺   1451篇
植物保护   7491篇
  2018年   1654篇
  2017年   1826篇
  2016年   1713篇
  2015年   1359篇
  2014年   1682篇
  2013年   4972篇
  2012年   3204篇
  2011年   3998篇
  2010年   2706篇
  2009年   2653篇
  2008年   4004篇
  2007年   3743篇
  2006年   3455篇
  2005年   3150篇
  2004年   3268篇
  2003年   3170篇
  2002年   3055篇
  2001年   3803篇
  2000年   3818篇
  1999年   2834篇
  1998年   1251篇
  1995年   1437篇
  1994年   1329篇
  1993年   1273篇
  1992年   2624篇
  1991年   2803篇
  1990年   2745篇
  1989年   2799篇
  1988年   2508篇
  1987年   2607篇
  1986年   2730篇
  1985年   2631篇
  1984年   2152篇
  1983年   1993篇
  1982年   1312篇
  1981年   1271篇
  1979年   2137篇
  1978年   1679篇
  1977年   1421篇
  1976年   1478篇
  1975年   1538篇
  1974年   1921篇
  1973年   1961篇
  1972年   1881篇
  1971年   1742篇
  1970年   1664篇
  1969年   1586篇
  1968年   1358篇
  1967年   1444篇
  1966年   1340篇
排序方式: 共有10000条查询结果,搜索用时 125 毫秒
91.
92.
93.
94.
95.
96.
97.
98.
Disseminated Aspergillus terreus infection was diagnosed in ten previously healthy adult dogs--nine German shepherds and one dalmatian. The disease was characterized by the presence of multiple granulomas and infarcts in a wide range of organs. The kidney, spleen, and skeletal system were most commonly and severely affected. Fungal hyphae were demonstrated in large numbers within granulomas and thrombi, and A. terreus was readily isolated by culture. This disseminated mycosis appears unique; in this series of cases there was no apparent predisposing factor, portal of entry, or primary focus for dissemination of the infection.  相似文献   
99.
The association of tumor-associated antigen (TAA) on the proliferation of BLV-infected lymphoblastoid B-cell lines (BL2M3 and BL312) was investigated. Flow cytometric analysis of the expression of TAA with monoclonal antibody (mAb) c143 showed high expression of TAA on the surfaces of BL2M3 and BL312 cells. A large amount of TAA was found in the culture supernatant of BL2M3 and BL312 cells as well as in the lysates of BL2M3 and BL312 cells. Culture supernatant but not lysates of BL2M3 and BL312 cells promoted the growth of either BL2M3 cells or BL312 cells. Furthermore, this growth promoting activity in culture supernatants of BL2M3 and BL312 cells was inhibited in a dose-dependent manner when cultured with mAb c143. These results suggested that TAA may be involved in the growth factor-mediated cell growth of bovine B-lymphoblastoid cell lines expressing TAA on their cell surface.  相似文献   
100.
The mean area and minimal diameter of 3 histochemically determined myofiber types (1, 2A, and 2B; myosin ATPase in acid buffer) were calculated in middle gluteal muscle biopsy specimens from 62 stallions, 47 Andalusians and 15 Arabians, ranging in age from 6 to 12 years. Fourteen Andalusians and 7 Arabians were untrained, and the remainder were actively endurance-trained. The 6-month training schedules involved walking, slow trotting, and cantering. Fourteen Andalusians were moderately endurance-trained, whereas the other 19 Andalusians and 8 Arabians were strongly endurance-trained. Significant differences were not recorded between untrained and endurance-trained Arabians with respect to the area (type 1, 3,194 +/- 869 microns 2 and 3,150 +/- 370 microns 2; type 2A, 3,819 +/- 890 microns 2 and 3,380 +/- 356 microns 2; and type 2B, 4,872 +/- 962 microns 2 and 4,417 +/- 646 microns 2) or minimal diameter (type 1, 52.2 +/- 7.4 microns and 52.8 +/- 3.1 microns; type 2A, 58.1 +/- 6.7 microns and 55.0 +/- 2.8 microns; and type 2B, 65.3 +/- 6.4 microns and 63.4 +/- 4.3 microns) of the 3 fiber types, nor between untrained and endurance-trained Andalusians with respect to the area (untrained, 3,990 +/- 690 microns 2; moderately endurance-trained, 3,882 +/- 347 microns 2; and strongly endurance-trained, 3,758 +/- 510 microns 2) and minimal diameter (untrained, 58.1 +/- 4.7 microns; moderately endurance-trained, 59.7 +/- 2.7 microns; and strongly endurance-trained, 58.7 +/- 4.5 microns) of 2A fibers.(ABSTRACT TRUNCATED AT 250 WORDS)  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