全文获取类型
收费全文 | 187859篇 |
免费 | 10415篇 |
国内免费 | 862篇 |
专业分类
林业 | 7791篇 |
农学 | 6077篇 |
基础科学 | 1388篇 |
23838篇 | |
综合类 | 33666篇 |
农作物 | 7489篇 |
水产渔业 | 9219篇 |
畜牧兽医 | 94736篇 |
园艺 | 2683篇 |
植物保护 | 12249篇 |
出版年
2020年 | 1716篇 |
2019年 | 2045篇 |
2018年 | 2871篇 |
2017年 | 3285篇 |
2016年 | 2944篇 |
2015年 | 2615篇 |
2014年 | 3186篇 |
2013年 | 7272篇 |
2012年 | 5951篇 |
2011年 | 7337篇 |
2010年 | 4856篇 |
2009年 | 4820篇 |
2008年 | 6938篇 |
2007年 | 6592篇 |
2006年 | 6077篇 |
2005年 | 5705篇 |
2004年 | 5306篇 |
2003年 | 5442篇 |
2002年 | 4926篇 |
2001年 | 5645篇 |
2000年 | 5754篇 |
1999年 | 4526篇 |
1998年 | 1976篇 |
1997年 | 1857篇 |
1996年 | 1730篇 |
1995年 | 2024篇 |
1994年 | 1777篇 |
1993年 | 1697篇 |
1992年 | 3565篇 |
1991年 | 3825篇 |
1990年 | 3709篇 |
1989年 | 3661篇 |
1988年 | 3346篇 |
1987年 | 3379篇 |
1986年 | 3479篇 |
1985年 | 3288篇 |
1984年 | 2750篇 |
1983年 | 2384篇 |
1979年 | 2486篇 |
1978年 | 1998篇 |
1977年 | 1646篇 |
1976年 | 1709篇 |
1975年 | 1806篇 |
1974年 | 2235篇 |
1973年 | 2222篇 |
1972年 | 2110篇 |
1971年 | 1951篇 |
1970年 | 1914篇 |
1969年 | 1900篇 |
1967年 | 1656篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
L. Baranauskait 《EPPO Bulletin》2004,34(3):335-337
Lithuania has requested that its whole territory should be recognized by the EU as a protected zone for Erwinia amylovora . Fireblight monitoring was performed in 1998/2002 with the aim of detecting and identifying the bacterium, and of determining its distribution in the country. The study consisted of periodic surveys (at least twice a year) of nurseries, orchards, collective farms and host plants, growing individually or in small groups, as well as the surrounding zone within a radius of 250 m. Tests, under conditions of quality control, were applied to host plants with and without symptoms, using detection methods such as ELISA and immunofluorescence (with polyclonal antibodies), semi-selective plating and pathogenicity. 相似文献
992.
P.A. Benjama M. El Gadda E. El Boustani C. El Modafar X. Nesme J. Cubero 《EPPO Bulletin》2004,34(3):403-406
Le meilleur moyen de contrôle du crown gall ( Agrobacterium tumefaciens ) est la prévention et donc la détection de la bactérie pathogène dans les sols prévus pour les pépinières. Pour cela nous avons essayé une approche moléculaire utilisant la PCR pour caractériser le plasmide pTi par le couple des amorces spécifiques F14/F44 dans les sols de diverses régions marocaines. Cette technique de détection représente un indicateur potentiel d'avertissement sur l'état d'infection des sols et plants par A. tumefaciens qui permet ainsi de déclencher la lutte biologique par le NoGall, produit commercial australien, hébergeant l'antagoniste K1026 . 相似文献
993.
G. Perrone A. Susca G. Stea G. Mulè 《European journal of plant pathology / European Foundation for Plant Pathology》2004,110(5-6):641-649
Black Aspergilli, and in particular Aspergillus carbonarius, are the main causes of contamination of grapes and their by-products by ochratoxin A. A PCR-based method was developed to detect DNA of A. carbonarius and A. japonicus. Two pairs of primers (CARBO1/2 and JAPO1/2) designed from the calmodulin gene, produced PCR products of 371 and 583 bp for A. carbonarius and A. japonicus, respectively. Primer specificity was tested with DNA of 107 strains belonging to Aspergillus section Nigri isolated mostly from grapes in Europe. The sensitivity of primers CARBO1/2 and JAPO1/2 was 12.5 pg when using pure total genomic DNA of the two species. The developed primers provide a powerful tool for detection of the main ochratoxigenic producing Aspergillus species in grapes. 相似文献
994.
Journal of Plant Diseases and Protection - The effects of ethanolic extracts (20 % per fresh weight (Fw) or 6 % per dry weight) of 20 different plant species were tested against late blight... 相似文献
995.
A. L. Echemendía P. L. Ramos L. Díaz R. Peral A. Fuentes M. Pujol G. González 《Plant pathology》2004,53(2):234-234
996.
997.
998.
N. L. Robertson 《Plant pathology》2004,53(5):569-576
A new virus named Nootka lupine vein-clearing virus (NLVCV) was isolated from Lupinus nootkatensis plants that were confined to a relatively small area in the Talkeetna mountains of south-central Alaska. Annual surveys (2000–03) consistently found leaf symptoms of pronounced vein clearing and mosaic on 3- to 4-week-old plants in late June. Spherical particles ≈30 nm in diameter were isolated from these leaves. Virions contained a single-stranded RNA of ≈4·0–4·2 kb and one species of capsid protein estimated to be ≈40 kDa. The double-stranded RNA profile from naturally infected leaves consisted of three major bands ≈4·2, 1·9 and 1·5 kbp. Protein extractions from either sap or virions of diseased plants reacted to polyclonal antiserum made against the virions in Western blot assays. A predicted PCR product ≈500 bp was synthesized from virion RNA using primers specific to the carmovirus RNA-dependent RNA polymerase (RDRP) gene. The nucleotide sequence of the amplified DNA did not match any known virus, but contained short regions of identity to several carmoviruses. Only species belonging to the Fabaceae were susceptible to NLVCV by mechanical inoculation. Based on dsRNA profile, size of virion RNA genome and capsid protein, and similarity of the RDRP gene to that of other carmoviruses, it is suggested that NLVCV is a member of the family Tombusviridae , and tentatively of the genus Carmovirus . As the host range, RDRP gene and dsRNA profile of NLVCV are different from those of known viruses, this is a newly described plant virus. 相似文献
999.
1000.
D. Hoffman J. Amorim A. DeClue 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2018,32(1):208-216