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   3611篇
  免费   277篇
  国内免费   7篇
耳鼻咽喉   15篇
儿科学   90篇
妇产科学   75篇
基础医学   372篇
口腔科学   38篇
临床医学   511篇
内科学   656篇
皮肤病学   27篇
神经病学   360篇
特种医学   120篇
外科学   310篇
综合类   34篇
预防医学   576篇
眼科学   65篇
药学   349篇
中国医学   2篇
肿瘤学   295篇
  2023年   12篇
  2022年   37篇
  2021年   92篇
  2020年   51篇
  2019年   80篇
  2018年   87篇
  2017年   65篇
  2016年   71篇
  2015年   88篇
  2014年   113篇
  2013年   172篇
  2012年   238篇
  2011年   296篇
  2010年   143篇
  2009年   144篇
  2008年   257篇
  2007年   251篇
  2006年   232篇
  2005年   227篇
  2004年   224篇
  2003年   203篇
  2002年   195篇
  2001年   38篇
  2000年   32篇
  1999年   42篇
  1998年   31篇
  1997年   42篇
  1996年   24篇
  1995年   30篇
  1994年   21篇
  1993年   16篇
  1992年   29篇
  1991年   30篇
  1990年   21篇
  1989年   23篇
  1988年   26篇
  1987年   19篇
  1986年   18篇
  1985年   17篇
  1984年   18篇
  1983年   8篇
  1982年   15篇
  1981年   15篇
  1980年   12篇
  1979年   9篇
  1977年   8篇
  1972年   8篇
  1971年   6篇
  1969年   9篇
  1962年   5篇
排序方式: 共有3895条查询结果,搜索用时 15 毫秒
1.
BACKGROUND: Solid organ transplant recipients may develop numerous or life-threatening skin cancers. In addition to aggressive standard treatment of skin cancer, reduction of immunosuppression has been considered an adjuvant therapeutic strategy, albeit without direct proof of efficacy. OBJECTIVE: To review the rationale for and evidence supporting the efficacy of reduction of immunosuppression for severe skin cancer in transplant recipients. METHODS: Review of the literature regarding direct and indirect evidence on reduction of immunosuppression for transplant-associated skin cancer. RESULTS: Although there are no randomized controlled trials of reduction of immunosuppression as a therapeutic intervention for transplant patients with skin cancer, multiple lines of evidence suggest that this strategy may be an effective adjuvant therapy. A randomized trial has demonstrated a lower incidence of skin cancer in transplant recipients after reduction of immunosuppression, albeit in a cohort not previously affected by skin cancer. Case series of reduction or cessation of immunosuppression demonstrate a lower incidence of skin cancer or improved outcomes of preexisting skin cancer. Lower overall immunosuppression is associated with a lower incidence of skin cancer. Multiple cancers affecting the skin have been shown to regress with reduction of immunosuppression. CONCLUSIONS: Reduction of immunosuppression may be an effective adjuvant therapeutic strategy when confronting severe transplant-associated skin cancer. The risks of reduction of immunosuppression must be better defined, and randomized trials of this strategy are necessary.  相似文献   
2.
3.
4.
Immunoreactivities of two monoclonal antibodies (MAbs) that recognize cone photopigments were tested in the retinas of congenitally blind retinal degenerate (rd) chicks and compared to normally sighted carrier chicks, heterozygous for the mutation. MAb OS-2 had been previously determined to label rod and most cone outer segment membranes in normal chick retinas and is believed to bind to an epitope that is common to several photopigments in chickens. MAb COS-1 labels specifically middle-to-long-wavelength-sensitive cone photopigments in a number of vertebrate species. In rd chicks MAb OS-2 labeled the same number of rod outer segments at the same densities as carrier chicks. However, cone outer segments were less frequently and significantly less heavily labeled with this MAb at all ages tested (1 day, 1 week and 2 weeks post hatching). MAb COS-1 labeled the same number of cone outer segments in both rd and carrier retinas at 1 day of age, however, those outer segments that were labeled in rd specimens had significantly fewer gold particles on them. At both 1 week and 2 weeks of age, rd chick retinas had a significant reduction in numbers of cone outer segments labeled by COS-1. These findings support the hypothesis that the cone photopigment protein is abnormal in the rd chick model of hereditary blindness and retinal degeneration.  相似文献   
5.
The electron microscopic autoradiographic tracing method has been used to examine the morphology and postsynaptic relationships of five projections (retina, cortical area 17, superior colliculus (tectal), parabigeminal nucleus, and pretectum) to the dorsal lateral geniculate nucleus of the greater bush baby galago crassicaudatus. Retinal terminals have been examined in the contralaterally innervated layer of each of the three matched pairs [parvi-(X-cell), magno- (Y--cell), and koniocellular (small, W-cell)] of geniculate layers. These terminals are large and contain pale mitochondria and round vesicles (RLPs). RLPs are presynaptic to juxtasomatic regions of parvi-and magnocellular neurons. In contrast, RLPs innervate more distal regions of konicellular neurons. Labeled cortical, tectal, and parabigeminal terminals are relatively small and contain round vesicles na dark mitochondria. Cortical terminals in each of the three representative layers are presynaptic to small diameter dendrites. No convergence of cortical and retinal terminals has been seen in any layer. Labeled tectal and parabigminal terminals are found primarily in the koniocellular layers, but the latter are also seen in all other layers. Tectal and parabigeminal terminals have been observed converging with retinal terminals on dendrites of some koniocellular neurons. Labeled pretectogeniculate terminals contain densely packed pleomorphic vesicles, dark mitochondria, and a dark cytoplasmic matric. These terminals, which are present in each of the representative layers, are presynaptic to conventional dendrites and profiles containing loosely despersed pleomorphic vesicles and a pale cytoplasmic matrix. © 1994 Wiley-Liss, Inc.  相似文献   
6.
7.
The purpose of this study was to enhance our understanding of the influence of the SARS crisis on the work and personal lives of community nurses.A total of 941 community nurses employed in a range of health-care settings in the province of Ontario, Canada, provided qualitative information about their perceptions of the impact of SARS in their workplace and in their personal lives. Themes and subthemes from the data were organized into 2 categories: The Experience (operational, organizational, and personal narratives), and Learning from the Experience (opportunities for personal learning, professional and policy development, and insight into policy and administrative implications). The findings are discussed within a framework of the learning opportunity presented by the crisis at the local, national, and international levels. The roles of effective communication, emergency response coordination, and education are considered with respect to policy development and administrative responses to infectious disease protocol. The findings are particularly relevant at this time of heightened fear of global epidemics.  相似文献   
8.
9.
The management of herniated lumbar intervertebral disc for patients not responding to an initial trial of conservative therapy is generally surgical. Little is known about the effect of continued conservative therapy on patients who have not improved or have deteriorated within the first 3 months. This study assessed which form of treatment, surgical or continued conservative therapy, is more cost-effective once an adequate trial of conservative therapy has failed. The study is a retrospective chart review of 55 white male truck drivers who presented with acutely herniated nucleus pulposus between 1985 and 1989. Twenty-five patients underwent surgery, and 30 underwent continued conservative therapy after initial rehabilitation. No significant difference was found in outcome (80% good or fair in both the surgical and conservative groups) or costs ($55,000 +/- $1,000/case during a 5-year period), hence no difference in the cost-effectiveness between the two treatment modalities (each $63,000 +/- $2,000/adjusted outcome). Conservatively treated patients, however, missed significantly more work. It was concluded that, for a patient not responding to the initial trial of conservative therapy, the option to undergo continued conservative treatment should be made available.  相似文献   
10.
Global gene expression was analyzed in early and late collagen-induced arthritis (CIA). Of 8734 cDNAs analyzed, 330 were induced and 55 downregulated greater than twofold in early or late disease. Hierarchical clustering of these 385 cDNAs demonstrated five distinct expression patterns differentiating early from late disease and correlating with histopathologic changes in the paw. Of the 385 cDNAs, 185 are known, characterized genes, the majority of which are not described as playing a role in arthritis. However, several of these genes are involved in pathological processes relating to arthritis, including apoptosis, inflammation, and cellular proliferation. One interesting gene, follistatin-like gene, is highly expressed along the margin of contact between inflammatory synovial pannus and eroding bone, suggesting a role in joint destruction. These results demonstrate that global gene expression profiles distinguish early and late CIA and reveal several genes novel to arthritis the further characterization of which will advance our understanding of arthritis.  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