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   12024篇
  免费   1281篇
  国内免费   27篇
耳鼻咽喉   101篇
儿科学   429篇
妇产科学   221篇
基础医学   1556篇
口腔科学   222篇
临床医学   1577篇
内科学   2353篇
皮肤病学   123篇
神经病学   1136篇
特种医学   563篇
外科学   1384篇
综合类   741篇
一般理论   13篇
预防医学   1170篇
眼科学   343篇
药学   741篇
中国医学   8篇
肿瘤学   651篇
  2023年   64篇
  2022年   104篇
  2021年   221篇
  2020年   138篇
  2019年   186篇
  2018年   305篇
  2017年   179篇
  2016年   191篇
  2015年   179篇
  2014年   278篇
  2013年   471篇
  2012年   514篇
  2011年   514篇
  2010年   354篇
  2009年   322篇
  2008年   481篇
  2007年   528篇
  2006年   548篇
  2005年   523篇
  2004年   475篇
  2003年   451篇
  2002年   447篇
  2001年   428篇
  2000年   413篇
  1999年   383篇
  1998年   187篇
  1997年   166篇
  1996年   205篇
  1995年   174篇
  1994年   134篇
  1993年   164篇
  1992年   292篇
  1991年   275篇
  1990年   293篇
  1989年   264篇
  1988年   235篇
  1987年   261篇
  1986年   214篇
  1985年   170篇
  1984年   164篇
  1983年   138篇
  1982年   118篇
  1981年   75篇
  1980年   73篇
  1979年   110篇
  1978年   101篇
  1977年   91篇
  1976年   76篇
  1975年   83篇
  1970年   56篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
53.
Chronic medical illness, and the resulting feelings of alienation, dependency, and distress, represent significant psychiatric issues in the general hospital setting. This article presents the results of the first 3 years of a pilot psychotherapy group at UCLA. This group differed from the typical didactic or support groups offered within the hospital in that membership was not limited to any particular diagnostic group. It was hypothesized that such a multidiagnosis group would facilitate exploration of dynamic and interpersonal issues. Both the group process and the response of the membership supported this hypothesis. However, an interesting distinction emerged within the group between members who saw themselves as chronically medically ill and those who defined themselves as disabled. "Disabled" members were generally less satisfied with the group and tended to benefit less than other members. In light of the above findings, we offer recommendations for establishment of similar groups in other hospital settings.  相似文献   
54.
The validity and reliability of hand-held dynamometry and Cybex dynamometry were investigated using maximal isometric contractions of the external rotators of the shoulder in 14 healthy male subjects. Three maximum voluntary contractions were recorded from each subject by a hand-held dynamometer and a Cybex isokinetic dynamometer at two testing sessions approximately 1 week apart. Analysis of variance did not reveal any significant differences between the mean peak torques obtained with either instrument or between days. The intrarater reliability was clearly established for both the hand-held dynamometer (r = 0.986) and Cybex dynamometer (r = 0.993). Within-day correlations between the two instruments accounted for 27% (day 1) and 60% (day 2) of the explainable variance. This suggests that although both techniques produced identical peak torque values and measured the same element of performance-strength, they did so in a slightly different manner. The possible nature of these differences is discussed.J Orthop Sports Phys Ther 1988;10(6):213-217.  相似文献   
55.
The International Conference on Primary Health Care, meeting in Alma-Ata, in the Soviet Union, September 12, 1978, expressed the need for urgent action by all governments, all health and development workers and the world community, to protect and promote the health of all people of the world. The world was caught by the phrase which emerged from this conference, Health For All by the Year 2000 and many have examined the articles of the Alma-Ata declaration and tried to implement them in their corner of the world. This paper describes a community-based smoking-cessation program which was implemented in the province of Nova Scotia, Canada, during the years 1980–1984. Primary to this project was the belief that people have the right and the duty to participate individually and collectively in planning and implementing their health care. This paper describes one community's effort in putting this belief into practice.Carol Smillie, B.N. BE.d. M.S.c. is an Assistant Professor at the School of Nursing, Dalhousie University, Halifax, Nova Scotia, Canada B3H 3J5, Katherine Coffin, BA, MEd is the Program Officer, Nova Scotia Office, Health Promotion Directorate Health and Welfare Canada, 5251 Duke Street, Halifax, Nova Scotia. Canada B3J 1P3. Kathryn Porter, B.A. (Gen)., is the Information and Education Coordinator, Nova Scotia Division Canadian Cancer Society. Brenda Ryan, B.A., M.B.A. is Program Evaluation Analysist, Nova Scotia Department of Health, 6088 Hollis Street, Halifax. Nova Scotia, Canada. This Project was funded by Health and Welfare Canada, Nova Scotia Department of Health, Nova Scotia Division Canadian Cancer Society, Requests for reprints should be addressed to: Professor Carol Smillie.  相似文献   
56.
57.
Primary insomnia, major depression, and narcolepsy are usually considered to be separate disorders, distinguished by different polysomnographic profiles. But do polysomnographic data provide adequate evidence to segregate the three disorders, or might they display fundamentally the same sleep disturbance, differing only in degree? To test the viability of these two alternate hypotheses, the authors performed a meta-analysis of controlled polysomnographic studies of these disorders. A summary measure of degree of sleep disturbance was constructed from five variables: wakefulness after sleep onset, percentage of stage 1 sleep, percentage of stage 3 + 4 sleep, rapid eye movement (REM) latency, and REM density. The results of available studies for each variable were combined using a weighted average of effect sizes. An overall "sleep disturbance index" was then calculated by combining the estimates for the five above listed variables. On both the individual measures and especially on the summary index, insomnia, depression, and narcolepsy were arrayed on a simple continuum of progressively more severe sleep disturbance--congruent with the clinical observation that these disorders display progressively more disturbed sleep. These findings suggest that sleep can be disturbed in only a limited number of ways: in evaluating sleep architecture, it may not be possible to elaborate much beyond a single axis of good-to-bad sleep. Thus, polysomnographic measures may not provide adequate evidence to classify insomnia, depression, and narcolepsy as separate entities.  相似文献   
58.
Back support mechanisms during manual lifting   总被引:1,自引:0,他引:1  
The ability of individuals to lift heavy loads without injury to the vertebral elements has led to the formulation of several explanations of this phenomenon. In this article, the existing literature on lifting is reviewed and mechanisms of back support during lifting are described. These mechanisms include the intra-abdominal pressure mechanism, the thoracolumbar fascia mechanism, and combinations of these mechanisms with the use of the erector spinae, multifidus, and psoas muscles. Physical therapists are often responsible for teaching patients and workers "proper" lifting techniques; however, controversy exists concerning the proper lift. Although lifting with the lower back in flexion and lifting in extension have been proposed, there are indications for each depending on individual circumstances. Lifting instructions for workers without low back injuries should be distinguished from instructions for patients with low back pain. General rules for lifting include: plan the lift, avoid twisting, keep the load close to the body, and bend at the knees.  相似文献   
59.
Morphology and function of lacrimal gland acinar cells in primary culture   总被引:6,自引:0,他引:6  
The objectives of the current investigation were fourfold: (1) to establish an effective procedure for the isolation of acinar cells from the rat lacrimal gland; (2) to evaluate the functional capacity of freshly isolated cells; (3) to determine defined culture conditions which permit maintenance of viable, differentiated cells, as well as secretory component (SC) production, during long-term culture; and (4) to characterize the morphological features of cultured cells. Acinar cells were isolated by serial incubation of gland fragments in chelating and enzymatic solutions, followed by centrifugation through a Ficoll gradient. The yield of viable cells/gland appeared to be age-dependent: cell recovery was inversely proportional to the age of the animals. Immunofluorescence analysis of freshly isolated cells showed the presence of SC, the IgA antibody receptor, within isolated cells. In addition, experiments with a labeled analog (Nle4-D-Phe7-alpha MSH) of alpha-melanocyte-stimulating hormone (alpha-MSH) demonstrated specific binding sites on freshly isolated cells; alpha-MSH is a known modulator of acinar protein secretion. Maximum binding of the alpha-MSH analog occurred within 30 min, was dependent upon cell density and was reduced by coincubation with unlabeled alpha-MSH. To determine the culture requirements of acinar cells, cells were cultured on a variety of substrates (plastic or modified plastic [Primaria], coated with or without extracellular matrix [Matrigel]) in the presence or absence of various supplements and/or fetal calf serum (FCS) for 0.7 to 3.5 weeks. Cell attachment, function and long-term viability required an extracellular matrix. Moreover, in long term cultures (25 days), acinar cell attachment was enhanced by the inclusion of supplements to media containing 10% FCS. Replacement of serum with fibroblast growth factor, high-density lipoprotein and an increased concentration of epidermal growth factor resulted in a distinct "cobblestone" morphology characteristic of epithelial cell cultures. Electron microscopic analysis of cells cultured in supplemented serum-free media demonstrated extensive rough endoplasmic reticulum and Golgi, intermediate filaments and numerous secretory granules, as well as tight junctions and desmosomes. In addition to cell maintenance and attachment, acinar cell synthesis and/or secretion of SC was positively influenced by inclusion of supplements in the media. In summary, we have isolated lacrimal gland acinar cells, which express receptors for IgA antibodies and alpha-MSH. In addition, we have defined culture conditions which permit the long-term maintenance of SC-secreting acinar cells.  相似文献   
60.
Cytotoxic lymphocytes are thought to kill target cells by means of potent cytotoxic granules that congregate near the microtubular organizing center and the Golgi apparatus at one pole of the killer cell. We searched for evidence of this type of polarization in 12 lip biopsy specimens from patients with acute and/or chronic graft-vs-host disease (GVHD) compared with two lip specimens from normal individuals. Lymphocytes with such polarization were found in contact with epithelial cells of the squamous mucosa in all 12 cases of GVHD, and cells of the cuboidal minor salivary duct epithelium were found in two of 11 evaluable cases. The data add support to the hypothesis that cytolytic lymphocytes attack epithelial cells in GVHD.  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