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   17046篇
  免费   1271篇
  国内免费   43篇
耳鼻咽喉   130篇
儿科学   431篇
妇产科学   402篇
基础医学   2659篇
口腔科学   283篇
临床医学   1704篇
内科学   3770篇
皮肤病学   305篇
神经病学   1481篇
特种医学   945篇
外国民族医学   4篇
外科学   2359篇
综合类   210篇
一般理论   4篇
预防医学   1212篇
眼科学   265篇
药学   974篇
  1篇
中国医学   8篇
肿瘤学   1213篇
  2021年   195篇
  2019年   220篇
  2018年   266篇
  2017年   185篇
  2016年   185篇
  2015年   256篇
  2014年   373篇
  2013年   520篇
  2012年   701篇
  2011年   711篇
  2010年   409篇
  2009年   469篇
  2008年   715篇
  2007年   721篇
  2006年   737篇
  2005年   655篇
  2004年   649篇
  2003年   648篇
  2002年   613篇
  2001年   570篇
  2000年   610篇
  1999年   476篇
  1998年   248篇
  1997年   231篇
  1996年   222篇
  1995年   183篇
  1994年   169篇
  1993年   165篇
  1992年   376篇
  1991年   354篇
  1990年   385篇
  1989年   376篇
  1988年   373篇
  1987年   356篇
  1986年   369篇
  1985年   348篇
  1984年   247篇
  1983年   200篇
  1982年   134篇
  1981年   136篇
  1980年   133篇
  1979年   168篇
  1978年   179篇
  1977年   160篇
  1976年   130篇
  1975年   175篇
  1974年   181篇
  1973年   135篇
  1972年   137篇
  1971年   139篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
141.
142.
Forty-three bronchoalveolar lavage (BAL) specimens from 40 immunocompromised patients were studied for the presence of cytomegalovirus (CMV) by rapid diagnostic methods. DNA in situ hybridization, cytology, and immunofluorescence were compared to conventional cell culture. Eleven (25%) of the 43 BAL samples grew CMV in culture. In situ hybridization detected 6 of these 11 for sensitivity, specificity, and predictive values of positive and negative of 55%, 94%, 75%, and 86%, respectively. Cytology had a sensitivity of 73% and specificity of 100%. Six Papanicolaou-stained cytospins were screened cytologically versus one hybridization cytospin, and the higher sensitivity of cytology may reflect this extensive sampling. The immunofluorescent method had a sensitivity equal to that of cytology (73%): however, the specificity (72%) was significantly less than that of either the probe or cytology. These data suggest that although in situ hybridization can be a rapid, useful method for detecting CMV in BAL specimens, cytology appears to be a more sensitive method.  相似文献   
143.
We examined a large consanguineous Druze family with McArdle disease for mutations in the glycogen myophosphorylase (PYGM) gene. All affected subjects were autozygous for a single G to A transition that abolishes the 5' consensus splice site in the first nucleotide of intron 14. The G to A transition is a rare mutation, with only one previous report in a single white subject heterozygous for this mutation and another, more common, mutation at codon 49. The kindred in our study is the first family reported in which disease is caused by homozygosity for this rare mutation. This kindred was originally reported as the first familial case of McArdle disease in the Druze.  相似文献   
144.
145.
146.
147.
Feuillard  J.  Maillet  F.  Goldschmidt  P.  Weiss  L.  Kazatchkine  M. D. 《Inflammation research》1991,32(3-4):343-346
The inhibitory activity of the sodium salt of the anti-inflammatory peptide N-acetyl-aspartyl-glutamic acid (NAAGA) on activation of the classical and alternative pathways of human complement was compared with that of the clinically used magnesium salt of NAAGA (NAAGA-Mg). Sodium salt of NAAGA (NAAGA-Na) inhibited both pathways of activation in a dose-dependent manner at concentration ranging from 1 to 10 mM by acting on formation and/or function of the C3 convertases as shown by the inhibitory capacity of the peptide on the release of the C3 cleavage fragment C3b and C3a. NAAGA-Na was as effective as NAAGA-Mg in inhibiting classical pathway activation at concentration above 10 mM. NAAGA-Na was more effective than NAAGA-Mg in inhibiting the alternative pathway since the sodium salt did not interfere with Mg-dependent formation of the alternative pathway C3 convertase.  相似文献   
148.
The relationship between myocardial contracture and cell calcium was studied in electrically paced, isolated perfused rabbit hearts. Isovolumic left ventricular dP/dt and end-diastolic pressure were utilized as indexes of contractility and ventricular stiffness. After 60 min of low flow (ischemia) without or with reperfusion at high flow for 10 min, calcium was measured in the mitochondrial fraction and used as an indicator of intracellular calcium. Low flow led to ventricular standstill and contracture, and reperfusion produced partial mechanical recovery with end-diastolic pressure remaining markedly elevated. Nifedipine (10(-7) M), an antagonist of myocardial calcium uptake, prevented contracture and permitted nearly complete mechanical recovery without elevation in diastolic pressure. Increases in mitochondrial calcium paralleled the severity of contracture and the lack of diastolic relaxation after reperfusion. Mitochondrial calcium did not increase in hearts protected by nifedipine. Results demonstrate a close relationship between mechanical changes induced by ischemia and accumulation of intracellular calcium.  相似文献   
149.
To help clarify the genetics of schizophrenia, the Department of Veterans Affairs Cooperative Studies Program has completed data collection for a genetic linkage study of schizophrenia. This article describes the methodological details of the data collection. Subsequent articles will describe the results of our genome scan, which is now in progress. The data collection protocol included the Diagnostic Interview for Genetic Studies, the Family Interview for Genetic Studies, a review of medical records, and the collection of blood for transformation into lymphoblast cell lines. Among relatives of schizophrenic probands, we assessed auditory attention and verbal memory with neuropsychological tests. Among the 166 families ascertained for the study, 143 had a single affected sib-pair, 17 had three affected siblings, one had five affected siblings and five had two sets of affected siblings. There was a total of 216 affected sib-pairs in these families. Using the n-1 rule, these families contain 188 independent affected sib-pairs.  相似文献   
150.
BACKGROUND: Kaposi's sarcoma (KS) is caused by Kaposi's sarcoma associated herpesvirus (KSHV/HHV-8), the eighth Herpesvirus found to infect humans. The molecular epidemiology of KSHV is related closely to ethnicity and geographical location of studied populations. There is little epidemiological and molecular information about KSHV strains circulating in Brazil. OBJECTIVES: To characterize KSHV strains isolated from AIDS patients with Kaposi's sarcoma (AIDS-KS) in Sao Paulo, Brazil, and to examine associations between KSHV subtypes, ethnicity and HIV risk categories. METHODS: AIDS-KS patients were recruited consecutively at the largest AIDS reference hospital in Sao Paulo. Fragments (420 bp) of the VR1 and VR2 regions of KSHV open reading frame (ORF) K1 were amplified by nested PCR and sequenced directly. RESULTS: We analysed 37 samples from 33 patients, and found subtypes A-C in 48%, 21% and 30% of patients respectively, including two patients infected with subtype A5, a first report from Brazil. Sexual orientation was associated with subtype: 12/14 (86%) patients with subtype A were male homo/bisexual, compared with 3/8 (38%) among patients infected with subtype C (P = 0.05). A higher proportion of male patients with subtype C were of Caucasian origin (7/8 (87%)), compared with 7/16 (44%) among male patients with subtype A (P = 0.08). CONCLUSIONS: This first detailed report of KSHV subtypes among AIDS-KS patients in Brazil reports the first isolation of KSHV subtype A5 in this country, and suggests KSHV strain transmission between different ethnic groups, and association of specific strains with sexual orientation.  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