首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   533篇
  免费   35篇
  国内免费   6篇
林业   3篇
农学   2篇
基础科学   5篇
  47篇
综合类   116篇
农作物   22篇
水产渔业   17篇
畜牧兽医   337篇
园艺   9篇
植物保护   16篇
  2020年   6篇
  2019年   8篇
  2018年   8篇
  2017年   5篇
  2016年   12篇
  2015年   7篇
  2014年   9篇
  2013年   22篇
  2012年   18篇
  2011年   16篇
  2010年   17篇
  2009年   12篇
  2008年   22篇
  2007年   21篇
  2006年   17篇
  2005年   20篇
  2004年   9篇
  2003年   13篇
  2002年   16篇
  2001年   15篇
  2000年   13篇
  1999年   11篇
  1996年   5篇
  1994年   7篇
  1993年   5篇
  1992年   13篇
  1991年   8篇
  1990年   9篇
  1989年   19篇
  1988年   5篇
  1987年   12篇
  1986年   15篇
  1985年   9篇
  1984年   7篇
  1983年   13篇
  1981年   6篇
  1979年   8篇
  1978年   5篇
  1977年   5篇
  1976年   5篇
  1975年   4篇
  1974年   6篇
  1972年   7篇
  1971年   6篇
  1970年   7篇
  1969年   6篇
  1968年   6篇
  1967年   5篇
  1966年   4篇
  1963年   4篇
排序方式: 共有574条查询结果,搜索用时 15 毫秒
51.
52.
53.
54.
55.
The dynamic glycosylation of serine or threonine residues on nuclear and cytosolic proteins by O-linked beta-N-acetylglucosamine (O-GlcNAc) is abundant in all multicellular eukaryotes. On several proteins, O-GlcNAc and O-phosphate alternatively occupy the same or adjacent sites, leading to the hypothesis that one function of this saccharide is to transiently block phosphorylation. The diversity of proteins modified by O-GlcNAc implies its importance in many basic cellular and disease processes. Here we systematically examine the current data implicating O-GlcNAc as a regulatory modification important to signal transduction cascades.  相似文献   
56.
57.
Human growth hormone (hGH) forms a 1:2 complex with the extracellular domain of its receptor-binding protein (hGHbp) as studied by crystallization, size exclusion chromatography, calorimetry, and a previously undescribed fluorescence quenching assay. These and other experiments with protein engineered variants of hGH have led to the identification of the binding determinants for two distinct but adjacent sites on hGH for the hGHbp, and the data indicated that there are two overlapping binding sites on the hGHbp for hGH. Furthermore, the binding of hGH to the hGHbp occurred sequentially; a first hGHbp molecule bound to site 1 on hGH and then a second hGHbp bound to site 2. Hormone-induced receptor dimerization is proposed to be relevant to the signal transduction mechanism for the hGH receptor and other related cytokine receptors.  相似文献   
58.
59.
The transport and fate of pesticides applied to ornamental plant nursery crops are not well documented. Methodology for analysis of soil and water runoff samples concomitantly containing the herbicides simazine (1-chloro-4,6-bis(ethylamino)-s-triazine) and 2,4-D ((2,4-dichlorophenoxy)acetic acid) was developed in this research to investigate the potential for runoff and leaching from ornamental nursery plots. Solid-phase extraction was used prior to analysis by gas chromatography and liquid chromatography. Chromatographic results were compared with determination by enzyme-linked immunoassay analysis. The significant analytical contributions of this research include (1) the development of a scheme using chromatographic mode sequencing for the fractionation of simazine and 2,4-D, (2) optimization of the homogeneous derivatization of 2,4-D using the methylating agent boron trifluoride in methanol as an alternative to in situ generation of diazomethane, and (3) the practical application of these techniques to field samples.  相似文献   
60.
Plant and animal species present on a coal fly ash slurry pond site and a dry deposit site were surveyed and sampled during a two-day period in October. Elemental analyses were determined for most of the species encountered. A total of 48 plant species were observed on the two sites, with 35 species on the wet site, and 20 on the dry site. Eighteen terrestrial and 7 aquatic animal species were found on the wet site, exclusive of vertebrates which were not studied with the exception of a carp (Cyprinus carpio). Eleven terrestrial invertebrates and one aquatic species were observed on the dry site. Neutron activation analysis was carried out for: Se, Hg, Cr, Ni, Zn, Co, Sb, Cd, and As. Using literature values for phytotoxicity, we conclude that, in general, plants did not accumulate toxic levels of metals. Only one plant (Impatiens biflora Willd.) showed a significant level of Cd. Of 20 plants analyzed on the wet site, 10 had excessive Se concentrations (>5 ppm); on the dry site 6 out of 18 had high Se values. In animals (Gryllus sp.; Melanoplus sp.; Trachelipus sp.; Lumbricus terrestris; Physa integra; Cyprinus carpio) the trace metal concentration was generally in between that of control animals and that of the fly ash itself. One exception included Zn, which, although the most variable element examined, was concentrated in all the terrestrial animals to levels higher than in fly ash. Crickets are the most consistent bioconcentrators with Cr, Se, and Zn at higher levels than for control animals. All animal species studied accumulated Se compared to controls.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号