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   1477篇
  免费   61篇
  国内免费   3篇
  1541篇
  2023年   6篇
  2022年   17篇
  2021年   47篇
  2020年   21篇
  2019年   20篇
  2018年   44篇
  2017年   30篇
  2016年   56篇
  2015年   69篇
  2014年   82篇
  2013年   120篇
  2012年   119篇
  2011年   92篇
  2010年   55篇
  2009年   45篇
  2008年   65篇
  2007年   64篇
  2006年   68篇
  2005年   43篇
  2004年   46篇
  2003年   35篇
  2002年   16篇
  2001年   18篇
  2000年   22篇
  1999年   21篇
  1997年   10篇
  1996年   7篇
  1994年   11篇
  1993年   7篇
  1992年   16篇
  1991年   14篇
  1990年   18篇
  1989年   22篇
  1988年   22篇
  1987年   19篇
  1986年   12篇
  1985年   16篇
  1984年   17篇
  1983年   7篇
  1982年   6篇
  1981年   6篇
  1980年   7篇
  1979年   18篇
  1978年   7篇
  1976年   12篇
  1974年   5篇
  1973年   10篇
  1972年   14篇
  1971年   5篇
  1970年   6篇
排序方式: 共有1541条查询结果,搜索用时 31 毫秒
991.
We report a case of bacterial pericarditis in an immunologically competent adult female caused by nonencapsulated Haemophilus influenzae (H influenzae) that was complicated by the acute development of life-threatening pericardial tamponade. H influenzae is a gram-negative coccobacillus, a pathogen most frequently associated with childhood exanthema (otitis media, meningitis) and, less frequently, adult pneumonia. Encapsulated, type b, or typable H influenzae is the strain implicated in childhood infections. On the other hand, nonencapsulated or nontypable H influenzae is the specific strain most often associated with exacerbation of chronic obstructive airway disease. Bacterial pericarditis caused by either subtype of H influenzae is exceedingly rare. We have located only 15 previously reported cases of H influenzae pericarditis occurring in adults in the world medical literature, the majority of which date back to the pre-antibiotic era. In 12 of these 15 cases (the only cases in which typing could be accomplished), the encapsulated strain of H influenzae was cultured from the pericardial fluid. Thus, to the best of our knowledge, we are reporting here the first case of bacterial pericarditis caused by nonencapsulated H influenzae in an immunologically competent adult.  相似文献   
992.
Whole genome re‐sequencing (WGRS) was conducted on a panel of 20 Cajanus spp. accessions (crossing parentals of recombinant inbred lines, introgression lines, multiparent advanced generation intercross and nested association mapping population) comprising of two wild species and 18 cultivated species accessions. A total of 791.77 million paired‐end reads were generated with an effective mapping depth of ~12X per accession. Analysis of WGRS data provided 5 465 676 genome‐wide variations including 4 686 422 SNPs and 779 254 InDels across the accessions. Large structural variations in the form of copy number variations (2598) and presence and absence variations (970) were also identified. Additionally, 2 630 904 accession‐specific variations comprising of 2 278 571 SNPs (86.6%), 166 243 deletions (6.3%) and 186 090 insertions (7.1%) were also reported. Identified polymorphic sites in this study provide the first‐generation HapMap in Cajanus spp. which will be useful in mapping the genomic regions responsible for important traits.  相似文献   
993.
This article is concerned with the development of some stochastic models better suited to describe the observed distributions of the menstruating interval relating to last closed-birth interval of two types of females. In this context, two models suited for couples using or not using contraception have been proposed. In the first case, the model assumes a constant conception rate (analogous to the constant hazard rate in the life-testing problem) over time whereas the second case assumes a time-dependent form of the conception rate. The models have been applied to the data collected in a survey conducted in Lucknow, and estimates of conception rate for the two types of females have also been obtained.  相似文献   
994.
995.
996.
In India, thousands of tons of textile mill sludge are produced every year. We studied the ability of epigeic earthworm Eisenia foetida to transform textile mill sludge mixed with cow dung and/or agricultural residues into value added product, i.e., vermicompost. The growth, maturation, mortality, cocoon production, hatching success and the number of hatchlings were monitored in a range of different feed mixtures for 11 weeks in the laboratory under controlled environmental conditions. The maximum growth and reproduction was obtained in 100% cow dung, but worms grew and reproduced favorably in 80% cow dung + 20% solid textile mill sludge and 70% cow dung + 30% solid textile mill sludge also. Addition of agricultural residues had adverse effects on growth and reproduction of worms. Vermicomposting resulted in significant reduction in C:N ratio and increase in TKN, TP, TK and TCa after 77 days of worm activity in all the feeds. Vermicomposting can be an alternate technology for the management of textile mill sludge if mixed with cow dung in appropriate quantities.  相似文献   
997.
To identify genetic factors contributing to type 2 diabetes (T2D), we performed large-scale meta-analyses by using a custom ~50,000 SNP genotyping array (the ITMAT-Broad-CARe array) with ~2000 candidate genes in 39 multiethnic population-based studies, case-control studies, and clinical trials totaling 17,418 cases and 70,298 controls. First, meta-analysis of 25 studies comprising 14,073 cases and 57,489 controls of European descent confirmed eight established T2D loci at genome-wide significance. In silico follow-up analysis of putative association signals found in independent genome-wide association studies (including 8,130 cases and 38,987 controls) performed by the DIAGRAM consortium identified a T2D locus at genome-wide significance (GATAD2A/CILP2/PBX4; p = 5.7 × 10(-9)) and two loci exceeding study-wide significance (SREBF1, and TH/INS; p < 2.4 × 10(-6)). Second, meta-analyses of 1,986 cases and 7,695 controls from eight African-American studies identified study-wide-significant (p = 2.4 × 10(-7)) variants in HMGA2 and replicated variants in TCF7L2 (p = 5.1 × 10(-15)). Third, conditional analysis revealed multiple known and novel independent signals within five T2D-associated genes in samples of European ancestry and within HMGA2 in African-American samples. Fourth, a multiethnic meta-analysis of all 39 studies identified T2D-associated variants in BCL2 (p = 2.1 × 10(-8)). Finally, a composite genetic score of SNPs from new and established T2D signals was significantly associated with increased risk of diabetes in African-American, Hispanic, and Asian populations. In summary, large-scale meta-analysis involving a dense gene-centric approach has uncovered additional loci and variants that contribute to T2D risk and suggests substantial overlap of T2D association signals across multiple ethnic groups.  相似文献   
998.

Background  

The ambition of most molecular biologists is the understanding of the intricate network of molecular interactions that control biological systems. As scientists uncover the components and the connectivity of these networks, it becomes possible to study their dynamical behavior as a whole and discover what is the specific role of each of their components. Since the behavior of a network is by no means intuitive, it becomes necessary to use computational models to understand its behavior and to be able to make predictions about it. Unfortunately, most current computational models describe small networks due to the scarcity of kinetic data available. To overcome this problem, we previously published a methodology to convert a signaling network into a dynamical system, even in the total absence of kinetic information. In this paper we present a software implementation of such methodology.  相似文献   
999.
1000.
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