全文获取类型
收费全文 | 70492篇 |
免费 | 4107篇 |
国内免费 | 36篇 |
专业分类
林业 | 3506篇 |
农学 | 2230篇 |
基础科学 | 340篇 |
9021篇 | |
综合类 | 10824篇 |
农作物 | 2525篇 |
水产渔业 | 3494篇 |
畜牧兽医 | 37033篇 |
园艺 | 963篇 |
植物保护 | 4699篇 |
出版年
2019年 | 627篇 |
2018年 | 1390篇 |
2017年 | 1374篇 |
2016年 | 1241篇 |
2015年 | 1113篇 |
2014年 | 1228篇 |
2013年 | 3167篇 |
2012年 | 2491篇 |
2011年 | 2744篇 |
2010年 | 1671篇 |
2009年 | 1557篇 |
2008年 | 2497篇 |
2007年 | 2447篇 |
2006年 | 2203篇 |
2005年 | 2073篇 |
2004年 | 1955篇 |
2003年 | 1957篇 |
2002年 | 1814篇 |
2001年 | 2044篇 |
2000年 | 1981篇 |
1999年 | 1642篇 |
1998年 | 678篇 |
1997年 | 650篇 |
1995年 | 692篇 |
1994年 | 628篇 |
1993年 | 602篇 |
1992年 | 1293篇 |
1991年 | 1425篇 |
1990年 | 1303篇 |
1989年 | 1310篇 |
1988年 | 1211篇 |
1987年 | 1181篇 |
1986年 | 1234篇 |
1985年 | 1231篇 |
1984年 | 991篇 |
1983年 | 933篇 |
1982年 | 598篇 |
1979年 | 920篇 |
1978年 | 718篇 |
1977年 | 707篇 |
1976年 | 729篇 |
1975年 | 727篇 |
1974年 | 892篇 |
1973年 | 863篇 |
1972年 | 831篇 |
1971年 | 749篇 |
1970年 | 797篇 |
1969年 | 759篇 |
1968年 | 672篇 |
1967年 | 675篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
73.
74.
75.
B. 《Forstwissenschaftliches Centralblatt》1898,20(9):509-511
Ohne Zusammenfassung 相似文献
76.
B. Perona 《Forstwissenschaftliches Centralblatt》1898,20(1):1-4
Ohne Zusammenfassung 相似文献
77.
78.
79.
Seven cultivars of red raspberry ( Rubus idaeus ) showed different susceptibility to infection by yellow rust ( Phragmidium rubi-idaei ) at two commercial plantations in Scotland and North Wales, The cultivars Latham, Chief and Boyne were completely resistant. Mailing Delight and Glen Clova supported more telial more than Mailing Jewel. In contrast the last named was the most susceptible cultivar at the aecial stage in Scotland but developed similar numbers of aecia to Glen Clova and Mailing Delight in Wales.
Meeker had an extended latent period, fewer and smaller pustules and a very small yield of urediniospores compared to the other susceptible cultivars, thus showing the characteristics of slow-rusting genotypes. At the Scottish site in 1982, where rust was less than in Wales, Meeker and Mailing Jewel performed differently to the other cultivars at the telial stage. Inoculation studies under controlled environmental conditions with urediniospores from each site revealed an interaction between cultivars and isolates suggesting that variation in pathogenicity is present in populations of P. rubi-idaei in the UK. 相似文献
Meeker had an extended latent period, fewer and smaller pustules and a very small yield of urediniospores compared to the other susceptible cultivars, thus showing the characteristics of slow-rusting genotypes. At the Scottish site in 1982, where rust was less than in Wales, Meeker and Mailing Jewel performed differently to the other cultivars at the telial stage. Inoculation studies under controlled environmental conditions with urediniospores from each site revealed an interaction between cultivars and isolates suggesting that variation in pathogenicity is present in populations of P. rubi-idaei in the UK. 相似文献
80.
Kaiping Deng Steffen Uhlig Laura B. Goodman Hon S. Ip Mary Lea Killian Sarah M. Nemser Jodie Ulaszek Shannon Kiener Matthew Kmet Kirstin Frost Karina Hettwer Bertrand Colson Kapil Nichani Anja Schlierf Andriy Tkachenko Mothomang Mlalazi-Oyinloye Andrew Scott Ravinder Reddy Gregory H. Tyson 《Journal of veterinary diagnostic investigation》2022,34(5):825
The COVID-19 pandemic presents a continued public health challenge. Veterinary diagnostic laboratories in the United States use RT-rtPCR for animal testing, and many laboratories are certified for testing human samples; hence, ensuring that laboratories have sensitive and specific SARS-CoV2 testing methods is a critical component of the pandemic response. In 2020, the FDA Veterinary Laboratory Investigation and Response Network (Vet-LIRN) led an interlaboratory comparison (ILC1) to help laboratories evaluate their existing RT-rtPCR methods for detecting SARS-CoV2. All participating laboratories were able to detect the viral RNA spiked in buffer and PrimeStore molecular transport medium (MTM). With ILC2, Vet-LIRN extended ILC1 by evaluating analytical sensitivity and specificity of the methods used by participating laboratories to detect 3 SARS-CoV2 variants (B.1; B.1.1.7 [Alpha]; B.1.351 [Beta]) at various copy levels. We analyzed 57 sets of results from 45 laboratories qualitatively and quantitatively according to the principles of ISO 16140-2:2016. More than 95% of analysts detected the SARS-CoV2 RNA in MTM at ≥500 copies for all 3 variants. In addition, for nucleocapsid markers N1 and N2, 81% and 92% of the analysts detected ≤20 copies in the assays, respectively. The analytical specificity of the evaluated methods was >99%. Participating laboratories were able to assess their current method performance, identify possible limitations, and recognize method strengths as part of a continuous learning environment to support the critical need for the reliable diagnosis of COVID-19 in potentially infected animals and humans. 相似文献