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   188篇
  免费   1篇
  国内免费   1篇
系统科学   2篇
丛书文集   2篇
教育与普及   1篇
现状及发展   29篇
研究方法   19篇
综合类   132篇
自然研究   5篇
  2021年   1篇
  2020年   1篇
  2019年   1篇
  2017年   3篇
  2016年   2篇
  2015年   2篇
  2014年   2篇
  2013年   1篇
  2012年   12篇
  2011年   18篇
  2010年   4篇
  2009年   10篇
  2008年   7篇
  2007年   10篇
  2006年   9篇
  2005年   10篇
  2004年   7篇
  2003年   6篇
  2002年   11篇
  2001年   5篇
  2000年   9篇
  1999年   5篇
  1996年   1篇
  1995年   1篇
  1994年   1篇
  1992年   2篇
  1991年   3篇
  1990年   3篇
  1989年   3篇
  1988年   1篇
  1987年   1篇
  1983年   1篇
  1982年   1篇
  1981年   2篇
  1980年   2篇
  1979年   2篇
  1978年   3篇
  1977年   1篇
  1976年   2篇
  1975年   3篇
  1974年   2篇
  1972年   1篇
  1971年   1篇
  1970年   4篇
  1969年   4篇
  1967年   3篇
  1966年   3篇
  1965年   3篇
排序方式: 共有190条查询结果,搜索用时 15 毫秒
61.
太原市二氧化硫污染状况及评价   总被引:1,自引:0,他引:1  
通过对太原市不同季节、不同监测位点大气二氧化硫(SO2)浓度的监测,分析了太原市SO2污染状况,指出在太原市对SO2排放企业的治理和管理工作势在必行。  相似文献   
62.
化学镀镍废液处理新工艺及机理研究   总被引:2,自引:0,他引:2  
通过化学沉淀法从废液中回收镍离子,继而采用硫酸亚铁为共沉剂,进一步处理上述废液,达到去除剩余镍离子的目的,考察了双氧水、氢氧化钠、硫酸亚铁用量及反应时间对化学镀镍废液处理结果的影响,并对反应机理进行了初步探讨,结果表明,新工艺双氧水用量少、回收镍纯度高,经济可行。  相似文献   
63.
The National Center for Biotechnology Information has created the dbGaP public repository for individual-level phenotype, exposure, genotype and sequence data and the associations between them. dbGaP assigns stable, unique identifiers to studies and subsets of information from those studies, including documents, individual phenotypic variables, tables of trait data, sets of genotype data, computed phenotype-genotype associations, and groups of study subjects who have given similar consents for use of their data.  相似文献   
64.
DNA methyltransferase 1 (DNMT1) is crucial for maintenance of methylation, gene regulation and chromatin stability. DNA mismatch repair, cell cycle regulation in post-mitotic neurons and neurogenesis are influenced by DNA methylation. Here we show that mutations in DNMT1 cause both central and peripheral neurodegeneration in one form of hereditary sensory and autonomic neuropathy with dementia and hearing loss. Exome sequencing led to the identification of DNMT1 mutation c.1484A>G (p.Tyr495Cys) in two American kindreds and one Japanese kindred and a triple nucleotide change, c.1470-1472TCC>ATA (p.Asp490Glu-Pro491Tyr), in one European kindred. All mutations are within the targeting-sequence domain of DNMT1. These mutations cause premature degradation of mutant proteins, reduced methyltransferase activity and impaired heterochromatin binding during the G2 cell cycle phase leading to global hypomethylation and site-specific hypermethylation. Our study shows that DNMT1 mutations cause the aberrant methylation implicated in complex pathogenesis. The discovered DNMT1 mutations provide a new framework for the study of neurodegenerative diseases.  相似文献   
65.
Lactoferrin     
Lactoferrin (LF) is a member of the transferrin family that is expressed and secreted by glandular epithelial cells and is found in the secondary granules of neutrophils. Originally viewed as an iron-binding protein in milk, with bacteriostatic properties, it is becoming increasingly evident that LF is a multifunctional protein to which several physiological roles have been attributed. These include regulation of iron homeostasis, host defense against a broad range of microbial infections, anti-inflammatory activity, regulation of cellular growth and differentiation and protection against cancer development and metastasis. While iron binding is likely central to some of the biological roles of LF, other activities, including specific interactions with mammalian receptors and microbial components, also contribute to the pleoitropic functional nature of this protein. In this article, recent advances in the understanding of these functions at the cellular and molecular level are discussed.  相似文献   
66.
Structure and function of the type 1 insulin-like growth factor receptor   总被引:18,自引:1,他引:17  
The type 1 insulin-like growth factor receptor (IGF-1R), a transmembrane tyrosine kinase, is widely expressed across many cell types in foetal and postnatal tissues. Activation of the receptor following binding of the secreted growth factor ligands IGF-1 and IGF-2 elicits a repertoire of cellular responses including proliferation, and the protection of cells from programmed cell death or apoptosis. As a result, signalling through the IGF-1R is the principal pathway responsible for somatic growth in foetal mammals, whereas somatic growth in postnatal animals is achieved through the synergistic interaction of growth hormone and the IGFs. Forced overexpression of the IGF-1R results in the malignant transformation of cultured cells: conversely, downregulation of IGF-1R levels can reverse the transformed phenotype of tumour cells, and may render them sensitive to apoptosis in vivo. Elevated levels of IGF-IR are observed in a variety of human tumour types, whereas epidemiological studies implicate the IGF-1 axis as a predisposing factor in the pathogenesis of human breast and prostate cancer. The IGF-1R has thus emerged as a therapeutic target for the development of antitumour agents. Recent progress towards the elucidation of the three-dimensional structure of the extracellular domain of the IGF-1R represents an opportunity for the rational assembly of small molecule antagonists of receptor function for clinical use.  相似文献   
67.
Gonococci in urethral exudates possess a virulence factor lost on subculture   总被引:23,自引:0,他引:23  
M E Ward  P J Watt  A A Glynn 《Nature》1970,227(5256):382-384
  相似文献   
68.
Zusammenfassung Es wird das Vorkommen des 4-äthyl- und des 2,5-Dimethylazulens in hochsiedenden Nebenprodukten des thermischen Crack-Verfahrens festgestellt. Die Azulene wurden durch ihre Spektren im Sichtbaren, sowie durch ihre Trinitrobenzolkomplexe charakterisiert.  相似文献   
69.
70.
Characterization of ovine hypothalamic hypophysiotropic TSH-releasing factor   总被引:16,自引:0,他引:16  
R Burgus  T F Dunn  D Desiderio  D N Ward  W Vale  R Guillemin 《Nature》1970,226(5243):321-325
  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