全文获取类型
收费全文 | 40355篇 |
免费 | 1756篇 |
国内免费 | 4597篇 |
专业分类
林业 | 2787篇 |
农学 | 4362篇 |
基础科学 | 619篇 |
4728篇 | |
综合类 | 18291篇 |
农作物 | 3350篇 |
水产渔业 | 2891篇 |
畜牧兽医 | 5523篇 |
园艺 | 1890篇 |
植物保护 | 2267篇 |
出版年
2024年 | 133篇 |
2023年 | 452篇 |
2022年 | 923篇 |
2021年 | 1080篇 |
2020年 | 1170篇 |
2019年 | 1364篇 |
2018年 | 968篇 |
2017年 | 1631篇 |
2016年 | 2069篇 |
2015年 | 1769篇 |
2014年 | 1399篇 |
2013年 | 2100篇 |
2012年 | 3065篇 |
2011年 | 3024篇 |
2010年 | 2397篇 |
2009年 | 2251篇 |
2008年 | 2490篇 |
2007年 | 3026篇 |
2006年 | 2682篇 |
2005年 | 2014篇 |
2004年 | 1705篇 |
2003年 | 1203篇 |
2002年 | 967篇 |
2001年 | 854篇 |
2000年 | 776篇 |
1999年 | 669篇 |
1998年 | 545篇 |
1997年 | 500篇 |
1996年 | 466篇 |
1995年 | 470篇 |
1994年 | 392篇 |
1993年 | 407篇 |
1992年 | 371篇 |
1991年 | 328篇 |
1990年 | 309篇 |
1989年 | 211篇 |
1988年 | 168篇 |
1987年 | 104篇 |
1986年 | 106篇 |
1985年 | 49篇 |
1984年 | 22篇 |
1983年 | 14篇 |
1982年 | 4篇 |
1981年 | 10篇 |
1980年 | 8篇 |
1979年 | 11篇 |
1978年 | 5篇 |
1963年 | 7篇 |
1956年 | 3篇 |
1955年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
42.
本文论述了中国山羊的起源、品种遗传资源及其遗传多样性的研究进展。最新调查 显示中国的山羊品种达50个,其中43个为地方品种,4个培育品种,3个引入品种,许多品种 具有独特的生产性能或适应能力。大量研究表明,我国山羊遗传多样性较为丰富。 相似文献
43.
44.
AIM:To explore the effects of PMA(phorbol-12-myristate-13-acetate, a tumor promoter, mimicking the action of diacylglycerol on PKC)and laminin on the adhesion and the proliferation of human hepatocellular carcinoma cells, and provide a new clue to liver cancer treatment.METHODS:Human hepatocellular carcinoma cell line(BEL-7402)was used to identify the endogenous laminin and protein kinase C-α(PKC-α) expression, and the effects of laminin and PMA on the adhesion and the proliferation were also investigatedin vitro.RESULTS:By the effect of exogenous laminin, human hepatocellular carcinoma cell (BEL-7402) possessed endogenous laminin expression and increased the adhesion and the proliferation, which was showed the synergistic action by the effect of PMA in combination. By the action of PMA alone, the proliferation and the PKC-α expression increased by exogenous laminin were decreased, and the adhesion and the endogenous laminin expression were increased.CONCLUSIONS:The finding suggested that the adhesion and the proliferation of human hepatocellular carcinoma cell were closely related to the effects of endogenous or exogenous laminin, which were associated with cPKC-α activity. Therefore, the application of anti-laminin antibody in combination with PKC antagonist might be a new clue to find out the therapy for liver cancer. 相似文献
45.
46.
47.
P. Galeffi G. Giunta S. Guida C. Cantale 《European journal of plant pathology / European Foundation for Plant Pathology》2002,108(5):479-483
Citrus tristeza virus (CTV) is one of the most destructive citrus virus diseases in the world. The construction of an engineered antibody, EMBL accession number AJ278109, able to specifically recognize its antigen, i.e. the coat protein of CTV, directly on infected plant material without any purification or manipulation of the entire woody plant. The potential uses of this engineered antibody are discussed. 相似文献
48.
Detection of Colletotrichum coccodes from soil and potato tubers by conventional and quantitative real-time PCR 总被引:4,自引:1,他引:4
Colletotrichum coccodes is the causal agent of the potato blemish disease black dot. Two PCR primer sets were designed to sequences of the ribosomal internal transcribed spacer (ITS1 and ITS2) regions for use in a nested PCR. The genus-specific outer primers (Cc1F1/Cc2R1) were designed to regions common to Colletotrichum spp., and the species-specific nested primers (Cc1NF1/Cc2NR1) were designed to sequences unique to C . coccodes . The primer sets amplified single products of 447 bp (Cc1F1/Cc2R1) and 349 bp (Cc1NF1/Cc2NR1) with DNA extracted from 33 European and North American isolates of C. coccodes. The specificity of primers Cc1NF1/Cc2NR1 was confirmed by the absence of amplified product with DNA of other species representing the six phylogenetic groups of the genus Colletotrichum and 46 other eukaryotic and prokaryotic plant pathogenic species. A rapid procedure for the direct extraction of DNA from soil and potato tubers was used to verify the PCR assay for detecting C. coccodes in environmental samples. The limit of sensitivity of PCR for the specific detection of C. coccodes when inoculum was added to soils was 3·0 spores per g, or the equivalent of 0·06 microsclerotia per g soil, the lowest level of inoculum tested. Colletotrichum coccodes was also detected by PCR in naturally infested soil and from both potato peel and peel extract from infected and apparently healthy tubers. Specific primers and a TaqMan fluorogenic probe were designed to perform quantitative real-time (TaqMan) PCR to obtain the same levels of sensitivity for detection of C. coccodes in soil and tubers during a first-round PCR as with conventional nested PCR and gel electrophoresis. This rapid and quantitative PCR diagnostic assay allows an accurate estimation of tuber and soil contamination by C. coccodes . 相似文献
49.
Bt对小地考虑呼吸作用的影响 总被引:5,自引:0,他引:5
利用红外CO2分析仪测定小地老虎幼虫呼吸节律的变化结果显示:小地老虎幼虫呼吸节律属于不规则波动型,取食含Bt烟叶的幼虫呼出的CO2量显著低于对照组,且呼吸节律的波动性也明显增大,说明小地考虑幼虫取食Bt后,呼吸代谢受到一定干扰,出现呼吸水平降低及代谢紊乱现象。 相似文献
50.
梨自交不亲和强度不同品种花柱S糖蛋白含量的差异 总被引:12,自引:2,他引:12
提取梨( Pyrus) 自交不亲和强度不同品种花柱可溶性蛋白质, 应用等电聚焦电泳法在凝胶板上分离出S 糖蛋白, 用图像解析法进行定量。结果表明, 花柱总S 糖蛋白含量因品种而异, 自交不亲和强、弱及自交亲和的品种每1 1048577;g 花柱可溶性蛋白中含总S 糖蛋白分别为1048578;1. 3 ng 、0. 7 ~ 0. 9 ng、 0. 7 ng 。不同的S 基因所表达的S 糖蛋白量差异显著, 即使是同一S 基因所对应的S 糖蛋白量也因品种而异。 相似文献