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   1174篇
  免费   84篇
  国内免费   14篇
耳鼻咽喉   4篇
儿科学   54篇
妇产科学   7篇
基础医学   112篇
口腔科学   20篇
临床医学   128篇
内科学   239篇
皮肤病学   4篇
神经病学   110篇
特种医学   183篇
外科学   106篇
综合类   57篇
一般理论   1篇
预防医学   76篇
眼科学   24篇
药学   51篇
  1篇
肿瘤学   95篇
  2023年   7篇
  2022年   13篇
  2021年   17篇
  2020年   12篇
  2019年   19篇
  2018年   17篇
  2017年   10篇
  2016年   8篇
  2015年   20篇
  2014年   21篇
  2013年   21篇
  2012年   46篇
  2011年   48篇
  2010年   28篇
  2009年   29篇
  2008年   23篇
  2007年   39篇
  2006年   37篇
  2005年   24篇
  2004年   36篇
  2003年   30篇
  2002年   38篇
  2001年   39篇
  2000年   39篇
  1999年   37篇
  1998年   34篇
  1997年   28篇
  1996年   29篇
  1995年   35篇
  1994年   25篇
  1993年   36篇
  1992年   26篇
  1991年   30篇
  1990年   35篇
  1989年   33篇
  1988年   36篇
  1987年   42篇
  1986年   34篇
  1985年   33篇
  1984年   16篇
  1983年   20篇
  1982年   12篇
  1981年   16篇
  1980年   20篇
  1979年   9篇
  1978年   13篇
  1977年   13篇
  1976年   5篇
  1975年   13篇
  1974年   7篇
排序方式: 共有1272条查询结果,搜索用时 46 毫秒
51.
In international reviews of psychiatric inpatient violence, one study of all types of patient violence found hostility, involuntary admission, and longer hospital stays associated with violence. A second study of comparison-group papers of patient assaults found younger males with schizophrenia, past violence, and substance abuse assaultive. The present review of raw assault data studies assessed characteristics of assaultive patients worldwide. It was hypothesized that patients with schizophrenia would present greatest assault risk. There were three analyses: International/no American studies (reviewed earlier), European studies, and merged International/American studies. Results revealed that male and female patients with schizophrenia, affective disorders, personality disorders, and other diagnoses presented greatest worldwide risk. Results partially support earlier findings. Given that individual institutional studies in this review reported significant assailant characteristics, a second finding is the absence of most of these institutional characteristics in this international review. Possible explanations for findings and a detailed methodological review are presented.  相似文献   
52.
53.
54.
Ribozyme-directed cleavage of mutant mRNAs appears to be a potentially effective therapeutic measure for dominantly inherited diseases. We previously demonstrated that two ribozymes targeted to the P23H mutation in rhodopsin slow photoreceptor degeneration in transgenic rats for up to 3 months of age when injected before significant degeneration at postnatal day (P) 15. We now have explored whether ribozyme rescue persists at older ages, and whether ribozymes are effective when injected later in the degeneration after significant photoreceptor cell loss. Recombinant adeno-associated virus (rAAV) vectors incorporating a proximal bovine rod opsin promoter were used to transfer either hairpin or hammerhead ribozyme genes to photoreceptors. For the study of long-term survival, rAAV was administered by subretinal injection at P15, and the rats were allowed to live up to 8 months of age. For the study of late-stage gene transfer, rAAV was administered at P30 or P45, when 40-45% of the photoreceptors already had degenerated. Eyes were examined functionally by the electroretinogram and structurally by morphometric analysis. When injected at P15, expression of either ribozyme markedly slowed the rate of photoreceptor degeneration for at least 8 months and resulted in significantly greater electroretinogram amplitudes at least up to P180. When injected at P30 or P45, virtually the same number of photoreceptors survived at P130 as when injected at P15. Ribozyme rescue appears to be a potentially effective, long-term therapy for autosomal dominant retinal degeneration and is highly effective even when the gene transfer is done after significant photoreceptor cell loss.  相似文献   
55.
BACKGROUND: Information is limited regarding the most effective methods of recruitment in internal medicine residency programs. To address this deficiency, we conducted a 4-year survey of students who interviewed at our program addressing aspects of the application and interview process to maximize recruitment. METHODS: A 25-item questionnaire was mailed after the match to all students who interviewed but did not match with our program from 1994 to 1997. RESULTS: The response rate varied from 35% in 1994 to 70% in 1997. Variables that showed significant improvement after intervention included brochure mailings, resident greeting, resident luncheon, and perceived resident satisfaction. There was a 50% increase in program applications and the percent of applicants rating our program in their first 3 choices rose from 21% in 1995 to 51% in 1997. CONCLUSIONS: The major factors influencing our applicant's decisions regarding our program included resident involvement and brochure development/mailings. We have focused our efforts on those components to make the greatest impact on increasing the attractiveness of our program for internal medicine training.  相似文献   
56.
PURPOSE: We previously demonstrated that 350 bp of the human rod cGMP phosphodiesterase beta-subunit (beta-PDE) gene promoter are sufficient to direct high levels of gene expression in human Y-79 retinoblastoma cells in vitro. In this study the cell specificity and expression pattern conferred by the short beta-PDE 5' flanking sequence in vivo were examined. METHODS: A construct containing the bacterial LacZ gene driven by a fragment of the beta-PDE 5' flanking region (-297 to +53) was used to generate transgenic mice. Gene expression was analyzed by measuring beta-galactosidase activity in tissue homogenates or visualizing enzymatic activity or protein production at a cellular level by in situ histochemistry or immunocytochemistry. RESULTS: Three independently derived transgenic lines were generated carrying the -297 to +53 beta-PDE 5' flanking region fragment. Within the retina, the reporter gene was specifically expressed in photoreceptors, consistent with the localization of endogenous beta-PDE. Significant expression of LacZ was not observed in other ocular or peripheral tissues. CONCLUSIONS: Photoreceptor-specific reporter gene expression is driven in vivo by a 350-bp segment of the beta-PDE 5' flanking sequence. This study demonstrates the utility of the human beta-PDE promoter for directing the expression of foreign genes to photoreceptors and suggests that the -297 to +53 beta-PDE 5' flanking region fragment may have important implications for therapeutic gene delivery to the visual cells.  相似文献   
57.
58.
A 34-year-old female patient presented with an intracranial subarachnoid hemorrhage and was found to have a dural arteriovenous fistula at the site of previous cervical meningocele repair. Subsequent occlusion was achieved with endovascular embolization. To our knowledge, the phenomenon of the development of a spinal dural fistula at the site of a meningocele repair has not been recorded before.  相似文献   
59.
Learned helplessness is the psychological state that results when an individual who is unable to exercise reasonable mastery in one situation incorrectly assumes that he or she is then unable to exercise reasonable control in other situations as well. This may complicate the delivery of health interventions since the individual with learned helplessness may assume that no care provider or treatment intervention can be of assistance. Elderly patients with Alzheimer's disease and other dementias are not immune to this stance of learned helplessness. This paper presents one possible psychosocial rehabilitation approach, the Project SMART (Stress Management and Relaxation Training) program, to the problem of learned helplessness. Based on the skills of adaptive stress-resistant problem solvers, Project SMART can be adapted to the needs of the elderly demented. The clinical and research implications are discussed.  相似文献   
60.
Violence in the United States is a national public health epidemic, and increasingly, much of this violence is committed by the country's young people. Critical Incident Stress Management (CISM) approaches emphasize a comprehensive continuum of services from pre-incident training through acute care to post-intervention services. This paper outlines a pre-incident approach to preventing youth violence for parents, teachers, and counselors. The approach includes the identification of a continuum of warning signs and five guidelines to address the underlying needs manifested in the warning signs. The implications are discussed.  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