全文获取类型
收费全文 | 14345篇 |
免费 | 716篇 |
国内免费 | 1252篇 |
专业分类
林业 | 1027篇 |
农学 | 2175篇 |
基础科学 | 128篇 |
629篇 | |
综合类 | 6051篇 |
农作物 | 1947篇 |
水产渔业 | 782篇 |
畜牧兽医 | 2046篇 |
园艺 | 701篇 |
植物保护 | 827篇 |
出版年
2024年 | 87篇 |
2023年 | 316篇 |
2022年 | 476篇 |
2021年 | 554篇 |
2020年 | 524篇 |
2019年 | 553篇 |
2018年 | 351篇 |
2017年 | 480篇 |
2016年 | 642篇 |
2015年 | 524篇 |
2014年 | 692篇 |
2013年 | 690篇 |
2012年 | 986篇 |
2011年 | 980篇 |
2010年 | 868篇 |
2009年 | 815篇 |
2008年 | 758篇 |
2007年 | 850篇 |
2006年 | 753篇 |
2005年 | 651篇 |
2004年 | 523篇 |
2003年 | 459篇 |
2002年 | 339篇 |
2001年 | 335篇 |
2000年 | 298篇 |
1999年 | 254篇 |
1998年 | 214篇 |
1997年 | 163篇 |
1996年 | 163篇 |
1995年 | 153篇 |
1994年 | 110篇 |
1993年 | 109篇 |
1992年 | 105篇 |
1991年 | 86篇 |
1990年 | 84篇 |
1989年 | 73篇 |
1988年 | 67篇 |
1987年 | 48篇 |
1986年 | 35篇 |
1985年 | 18篇 |
1984年 | 22篇 |
1983年 | 8篇 |
1982年 | 11篇 |
1981年 | 10篇 |
1980年 | 10篇 |
1979年 | 10篇 |
1978年 | 14篇 |
1977年 | 11篇 |
1976年 | 15篇 |
1956年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
MHC及其在动物遗传与育种方面的应用 总被引:3,自引:0,他引:3
主要组织相容性复合体(Major histocompatibility complex,MHC)不仅与移植排斥反应有关,而且还与动物的一些经济性状密切相关。文章主要阐述了MHC的结构、功能和遗传特性,并且介绍了MHC基因作为遗传标记在动物遗传与育种方面的应用。 相似文献
132.
133.
134.
随着近年分子生物学技术的发展与应用,植物霜霉病抗性的研究有了长足的进展。本文就拟南芥抗霜霉病基因的克隆与结构分析,抗病信号传导,防卫反应和系统获得抗性,以及寄主一寄生菌共进化冲突方面进行了综述,并就今后的研究进行了展望。 相似文献
135.
Molecular identification methods are widely used for the classification of organisms worldwide. Entomopathogenic nematodes
are the most often isolated insect parasitic nematodes in the tropical and subtropical regions. In our investigation, PCR-RFLP
(Polymerase Chain Reaction — Restriction Fragment Length Polymorphism) of the ITS region (Internal Transcribed Spacer) on
the ribosomal (r) DNA of three entomopathogenic nematodes isolated from Ankara, Turkey, was analyzed for identification. The
ITS region of rDNA was amplified by PCR and then digested with the following nine restriction enzymes: Alu I, Dde I, Hae III,
Hha I, Hind III, Hinf I, Hpa II, Rsa I and Sau 3AI. The amplified and restricted sequences of the ITS regions were separated
by agarose gel electrophoresis and the RFLP patterns of these three species were shown in this study. According to our results,
these species were identified asSteinernema feltiae, Steinernema carpocapsae andHeterorhabditis bacteriophora.
http://www.phytoparasitica.org posting Nov. 4, 2005. 相似文献
136.
2012年,北美地区发生了一种由山毛榉李氏垫刃线虫麦肯恩亚种(Litylenchus crenatae mccannii)引起的森林新病害——山毛榉叶线虫病,病情蔓延迅速,已扩散至美国和加拿大30个县。病原为害山毛榉属植物,可造成病树成片死亡。由于山毛榉是北美温带阔叶林的主要构成树种和重要用材树种,新病害已引起美国农业部的高度重视并采取积极的应对措施。我国分布5种山毛榉属植物(均为特有种),是我国南方森林的主要组成树种。鉴于我国每年从北美进口大量山毛榉木材,病原线虫存在随进境木材传入国内的巨大风险。因此,检疫部门应开展风险评估,口岸应针对性开展山毛榉叶线虫病的检测。本文主要介绍了山毛榉叶线虫病的发生历史、分布范围、为害症状、病原线虫形态学特征、生活史、传播途径、分子检测方法等方面的信息,以期为口岸检疫工作提供参考。 相似文献
137.
Evolution of resistance to herbicides in weeds is becoming an increasing problem worldwide. To develop effective strategies for weed control, a thorough knowledge of the basis of resistance is required. Although non‐target‐site‐based resistance is widespread, target site resistance, often caused by a single nucleotide change in the gene encoding the target enzyme, is also a common factor affecting the efficacies of key herbicides. Therefore, fast and relatively simple high‐throughput screening methods to detect target site resistance mutations will represent important tools for monitoring the distribution and evolution of resistant alleles within weed populations. Here, we present a simple and quick method that can be used to simultaneously screen for up to 10 mutations from several target site resistance‐associated codons in a single reaction. As a proof of concept, this SNaPshot multiplex method was successfully applied to the genotyping of nine variable nucleotide positions in the CT domain of the chloroplastic ACCase gene from Lolium multiflorum plants from 54 populations. A total of 10 nucleotide substitutions at seven of these nine positions (namely codons 1781, 1999, 2027, 2041 2078, 2088 and 2096) are known to confer resistance to ACCase‐inhibiting herbicides. This assay has several advantages when compared with other methods currently in use in weed science. It can discriminate between different nucleotide changes at a single locus, as well as screening for SNPs from different target sites by pooling multiple PCR products within a single reaction. The method is scalable, allowing reactions to be carried out in either 96‐ or 384‐well plate formats, thus reducing work time and cost. 相似文献
138.
在对广东省主要珍贵树种上的线虫进行调查时从格木Erythrophleum fordii上分离到一种隐皮孢囊线虫,经形态特征观察和测量数据分析,将其鉴定为卡勒萨隐皮孢囊线虫Cryphodera kalesari。其诊断特征为:雌虫椭圆形至近球形,头部具有1个唇盘和2~3个唇环,口针长33.6~37.8μm,阴门唇突出,阴门与肛门之间区域凹陷,肛阴距为42~72μm;2龄幼虫头部具1个明显的唇盘和3个唇后环纹,口针长24.8~29.5μm,口针基部球前缘凹陷,侧区3条侧线,尾长圆锥形,长38~53.5μm,尾末端细圆,透明尾长17.1~25.1μm,侧尾腺孔位于肛门后2~5环;雄虫未发现。本研究首次获得了卡勒萨隐皮孢囊线虫的rDNA(LSU D2D3和ITS)序列,为此线虫的鉴定提供了可靠的分子数据。本研究还分析了卡勒萨隐皮孢囊线虫与本属其他种类的系统进化关系。卡勒萨隐皮孢囊线虫为中国的地理新记录种。格木为隐皮孢囊线虫的新寄主。 相似文献
139.
140.
Jiaoyan Yang Qingye Zhang Mingjun Liao Min Xiao Wenjing Xiao Shao Yang Jian Wan 《Pest management science》2009,65(3):260-265
BACKGROUND: Magnaporthe grisea (Hebert) ME Barr infection is one of the most serious diseases for cultivated rice in the world. Sterol 14α‐demethylase (CYP51) is an important drug target for microbial pathogenic infections. To exploit specific and effective fungicides for M. grisea better, the authors have analysed the characteristics of interaction between sterol 14α‐demethylase from M. grisea (MGCYP51) and azoles. MGCYP51 with truncation of N‐terminal residues was cloned and expressed in E. coli, difference binding spectra of MGCYP51 induced by addition of four commercial azoles were determined and molecular modelling of MGCYP51 based on the crystal structure of Mycobacterium tuberculosis Lehmann & Newman and docking with the azoles were performed. RESULTS: The affinity of the azoles for MGCYP51 was positively correlated with their hydrophobicity. Amino acid residues Tyr112, Phe120, Phe220, His308 and Phe497 of MGCYP51, forming a large hydrophobic cavity, are the key residues interacting with azole fungicides. Furthermore, Phe220 and Phe497 are fungus and species specific respectively. CONCLUSION: The results suggest that the more potent azole fungicides for MGCYP51 should possess more hydrophobic groups interacting with residues Phe220 and Phe497. Copyright © 2009 Society of Chemical Industry 相似文献