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   5735篇
  免费   667篇
  国内免费   10篇
耳鼻咽喉   81篇
儿科学   164篇
妇产科学   121篇
基础医学   926篇
口腔科学   200篇
临床医学   636篇
内科学   1344篇
皮肤病学   78篇
神经病学   437篇
特种医学   232篇
外科学   686篇
综合类   98篇
一般理论   7篇
预防医学   636篇
眼科学   52篇
药学   378篇
中国医学   3篇
肿瘤学   333篇
  2023年   48篇
  2022年   47篇
  2021年   132篇
  2020年   89篇
  2019年   133篇
  2018年   138篇
  2017年   86篇
  2016年   104篇
  2015年   140篇
  2014年   182篇
  2013年   228篇
  2012年   336篇
  2011年   310篇
  2010年   189篇
  2009年   164篇
  2008年   253篇
  2007年   270篇
  2006年   231篇
  2005年   252篇
  2004年   225篇
  2003年   192篇
  2002年   215篇
  2001年   163篇
  2000年   174篇
  1999年   140篇
  1998年   68篇
  1997年   53篇
  1996年   55篇
  1995年   53篇
  1994年   41篇
  1993年   40篇
  1992年   87篇
  1991年   108篇
  1990年   106篇
  1989年   105篇
  1988年   89篇
  1987年   71篇
  1986年   92篇
  1985年   90篇
  1984年   56篇
  1983年   91篇
  1981年   54篇
  1980年   39篇
  1979年   65篇
  1978年   49篇
  1977年   41篇
  1976年   39篇
  1975年   50篇
  1973年   52篇
  1972年   45篇
排序方式: 共有6412条查询结果,搜索用时 0 毫秒
141.
A cost analysis of two anterior cervical fusion procedures   总被引:5,自引:0,他引:5  
Multilevel anterior cervical discectomy and fusion (ACDF) remains a difficult problem. A recently described surgical technique for multilevel ACDF has eliminated the morbid complications associated with harvesting iliac crest bone graft (ICBG) while maintaining the advantages of using autologous bone graft. A matched-pairs t test was used to compare the estimated costs of 27 ACDFs using titanium surgical mesh, local autologous bone graft, and anterior plate instrumentation with 27 ACDFs using ICBG and plate fixation. The three variables considered were cage cost, operating time (cost), and hospitalization cost. The estimated costs for the two surgical procedures were not significantly different. Thus, the time saved by not harvesting an ICBG was comparable to the cost of the cage. Harvesting ICBG also increased the morbidity rate by 22%.  相似文献   
142.
143.
144.
Depression and trauma are common among women living with HIV. This is the first study to track the longitudinal course of depression and examine the relationship between depression and trauma over time among women in South Africa. HIV-infected and uninfected women (N = 148) were assessed at baseline and one year later. Results of a path analysis show the multi-directional and entwined influence of early life stress, other life-threatening traumas across the lifespan, depression and PTSD over the course of HIV. We also observed higher rates of depressive symptomatology and more persistent cases among infected women compared to uninfected women, as well as a more consistent and enduring relationship between childhood trauma and depression among women living with HIV. The present study is unique in documenting the course of untreated depression and PTSD in women with and without HIV infection with a high prevalence of early childhood trauma.  相似文献   
145.
146.
147.
148.
149.
Chromosomal DNA from Streptococcus mutans 6715 (serotype g) was cloned into Escherichia coli K-12 by using the cosmid pJC74 cloning vector and a bacteriophage λ in vitro packaging system. Rabbit antiserum against S. mutans extracellular proteins was used for immunological screening of the clone bank. Twenty-one clones produced weak to strong precipitin bands around the colonies, but only after the λ c1857 prophage was induced by being heated to lyse the E. coli cells. None of the clones expressed enzyme activity for several known S. mutans extracellular enzymes. One of these clones contained a 45-kilobase recombinant plasmid designated pYA721. An 8.5-kilobase fragment of S. mutans DNA from pYA721 was isolated and recloned into the BamHI restriction site of the plasmid vector pACYC184 to construct pYA726. pYA726 contained all, or nearly all, of the gene for a surface protein antigen (the spaA protein) of S. mutans 6715. This was deduced from immunological studies in which extracts of cells harboring pYA726 reacted with antisera against both purified 6715 spaA protein (about 210,000 daltons) and the immunologically similar antigen I/II of serotype c strains of S. mutans. In addition, the S. mutans spaA protein was found to possess at least one antigenic determinant not present on the protein specified by pYA726. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of E. coli clone extracts revealed that pYA726 produced a polypeptide with a molecular mass of about 180,000 daltons which was predominantly found in the periplasmic space of E. coli cells. Antisera to the spaA protein of S. mutans reacted with extracellular protein from representative strains of S. mutans serotypes a, c, d, e, f, and g, but not b.  相似文献   
150.
Writing epilepsy is a rare reflex syndrome in which seizures are triggered by writing. We describe a 33-year-old, right-handed man, with a history of juvenile absence epilepsy in remission and a family history of epilepsy, in whom myoclonic jerks precipitated exclusively by writing started at the age of 30. Intensive video/EEG monitoring during neuropsychological tests revealed, at about 1 minute after starting to write, a dystonic posture, followed by myoclonic jerks involving the right hand that shortly after became generalized. Concomitantly, the ictal EEG documented generalized hypersynchronous polyspike-wave discharges, maximal over the right parietocentral area. SPECT revealed an ictal hyperperfusion and interictal hypoperfusion over right parietofrontal regions, and fMRI showed extensive and intense left frontal, supplementary motor area activation, induced by writing. This case study provides some evidence supporting the hypothesis that the mechanism underlying writing-triggered seizures may be a generalized seizure process, with a focal cortical trigger zone, presumed to be the left frontal lobe as suggested by clinical and fMRI data. A relevant role played by the right hemisphere (right parietofrontal region) is postulated in the full-blown expression of reflex epileptogenesis, as supported by EEG and SPECT findings.  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