全文获取类型
收费全文 | 150047篇 |
免费 | 8673篇 |
国内免费 | 85篇 |
专业分类
林业 | 5433篇 |
农学 | 4378篇 |
基础科学 | 1031篇 |
16943篇 | |
综合类 | 25493篇 |
农作物 | 5426篇 |
水产渔业 | 7335篇 |
畜牧兽医 | 80598篇 |
园艺 | 1778篇 |
植物保护 | 10390篇 |
出版年
2018年 | 1886篇 |
2017年 | 2085篇 |
2016年 | 1946篇 |
2015年 | 1752篇 |
2014年 | 2178篇 |
2013年 | 5626篇 |
2012年 | 3991篇 |
2011年 | 5006篇 |
2010年 | 3113篇 |
2009年 | 3220篇 |
2008年 | 4864篇 |
2007年 | 4600篇 |
2006年 | 4468篇 |
2005年 | 4153篇 |
2004年 | 4120篇 |
2003年 | 4113篇 |
2002年 | 4051篇 |
2001年 | 4833篇 |
2000年 | 4644篇 |
1999年 | 3787篇 |
1998年 | 1604篇 |
1997年 | 1640篇 |
1996年 | 1515篇 |
1995年 | 1878篇 |
1994年 | 1685篇 |
1993年 | 1611篇 |
1992年 | 3276篇 |
1991年 | 3389篇 |
1990年 | 3462篇 |
1989年 | 3412篇 |
1988年 | 3136篇 |
1987年 | 3238篇 |
1986年 | 3266篇 |
1985年 | 3155篇 |
1984年 | 2673篇 |
1983年 | 2368篇 |
1982年 | 1606篇 |
1981年 | 1481篇 |
1980年 | 1434篇 |
1979年 | 2317篇 |
1978年 | 1912篇 |
1977年 | 1629篇 |
1976年 | 1441篇 |
1975年 | 1541篇 |
1974年 | 2077篇 |
1973年 | 2088篇 |
1972年 | 2054篇 |
1971年 | 1816篇 |
1970年 | 1714篇 |
1969年 | 1571篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
42.
Detection of a broad range of potato viruses in a single assay by mechanical inoculation of herbaceous test plants 总被引:1,自引:0,他引:1
To optimize mechanical inoculation of test plants as part of the regulated post-entry quarantine testing of stolon- and tuber-forming Solanum spp. (including potato), nine test plant species have been screened for their ability to detect 22 potato-infecting viruses. These included all the common mechanically transmissible potato viruses and most of the viruses found in potato incidentally. The symptoms observed after mechanical inoculation are shown for each combination of test plant species and virus. Under given conditions, Nicotiana occidentalis -P1 and Nicotiana hesperis -67A were found to detect reliably 20 and 18 out of 22 viruses respectively. These and former results on the seed-transmissible viruses and Andean potato mottle virus demonstrate that these Nicotiana species are very suitable for post-entry quarantine testing. Addition of either Chenopodium amaranticolor or Chenopodium quinoa to these two species may slightly extend the range of viruses. Therefore, using C. amaranticolor / C. quinoa , N. hesperis -67A and N. occidentalis -P1 for the biological screening of imported Solanum spp. will improve both the efficiency and the quality of post-entry quarantine testing. 相似文献
43.
44.
45.
46.
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
47.
B J Culliton 《Science (New York, N.Y.)》1989,245(4919):697-698
48.
49.
J B Herrick 《Journal of the American Veterinary Medical Association》1992,201(12):1854-1855
50.
To investigate the neuropathogenesis of feline immunodeficiency virus (FIV) infection in vitro, we have utilized three populations of cultured feline neural cells (astrocytes, microglia, brain endothelium) to assess the relative susceptibility to FIV infection, ability to produce viral antigens, and effects of infection on cell survival. Astrocytes appeared to be the most susceptible to infection, followed by microglia, whereas brain endothelial cells were relatively resistant to infection. Astrocyte infection resulted in syncytium formation and cell death, while microglial cells remained persistently and productively infected, without obvious cytopathic effects. These results suggest that FIV entry into the central nervous system probably does not occur via infected endothelium and that both astrocytes and microglia are more likely target cells for the virus. 相似文献