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   19870篇
  免费   1335篇
  国内免费   77篇
耳鼻咽喉   219篇
儿科学   455篇
妇产科学   492篇
基础医学   3018篇
口腔科学   752篇
临床医学   2262篇
内科学   4029篇
皮肤病学   403篇
神经病学   1918篇
特种医学   559篇
外科学   2044篇
综合类   115篇
一般理论   9篇
预防医学   1873篇
眼科学   289篇
药学   1614篇
中国医学   132篇
肿瘤学   1099篇
  2023年   187篇
  2022年   129篇
  2021年   526篇
  2020年   340篇
  2019年   556篇
  2018年   782篇
  2017年   593篇
  2016年   642篇
  2015年   766篇
  2014年   884篇
  2013年   1242篇
  2012年   1798篇
  2011年   1855篇
  2010年   904篇
  2009年   703篇
  2008年   1250篇
  2007年   1224篇
  2006年   1169篇
  2005年   1074篇
  2004年   1034篇
  2003年   920篇
  2002年   844篇
  2001年   161篇
  2000年   131篇
  1999年   129篇
  1998年   113篇
  1997年   99篇
  1996年   113篇
  1995年   71篇
  1994年   50篇
  1993年   55篇
  1992年   62篇
  1991年   49篇
  1990年   56篇
  1989年   48篇
  1988年   34篇
  1987年   43篇
  1986年   49篇
  1985年   43篇
  1984年   61篇
  1983年   34篇
  1982年   47篇
  1981年   56篇
  1980年   36篇
  1979年   30篇
  1978年   22篇
  1977年   22篇
  1975年   21篇
  1972年   16篇
  1970年   16篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
21.
A model is described for obtaining long-term and stable discriminative conditioning-related slow-potential and single-unit responses from the frontal cortex of urethane-anesthetized rats. Responses were recorded and analyzed to reinforced (rewarding medial forebrain bundle stimulation) and non-reinforced tone cues. In the present study, cortical event-related slow potentials provided an adequate index of the level of discriminative conditioning. Single-unit response patterns are described for 57 neurons which demonstrated a discriminative response to either the reinforced or non-reinforced tone cue.  相似文献   
22.
BACKGROUND: Acute pain is common after cardiac surgery and can keep patients from participating in activities that prevent postoperative complications. Accurate assessment and understanding of pain are vital for providing satisfactory pain control and optimizing recovery. OBJECTIVES: To describe pain levels for 5 activities expected of patients after cardiac surgery on postoperative days 1 to 6 and changes in pain levels after chest tube removal and extubation. METHODS: Adults who underwent cardiac surgery were asked to rate the pain associated with various types of activities on postoperative days 1 to 6. Pain levels were compared by postoperative day, activity, and type of cardiac surgery. Pain scores before and after chest tube removal and extubation also were analyzed. RESULTS: Pain scores were higher on earlier postoperative days. The order of overall pain scores among activities (P < .01) from highest to lowest was coughing, moving or turning in bed, getting up, deep breathing or using the incentive spirometer, and resting. Changes in pain reported with coughing (P = .03) and deep breathing or using the incentive spirometer (P = .005) differed significantly over time between surgery groups. After chest tubes were discontinued, patients had lower pain levels at rest (P = .01), with coughing (P = .05), and when getting up (P = .03). CONCLUSIONS: Pain relief is an important outcome of care. A comprehensive, individualized assessment of pain that incorporates activity levels is necessary to promote satisfactory management of pain.  相似文献   
23.
Quantitative immunoblotting assay of blood coagulation factor XII   总被引:2,自引:0,他引:2  
The immunoblotting technique was applied to the study of Factor XII (F.XII) in plasma. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) of whole plasma followed by electroblotting of the electropherograms to nitrocellulose (NC) membranes and immunologic detection by a double antibody technique was used. 125-F.XII was transferred to the NC membrane in amounts proportional to the amount applied to the gel provided that a constant amount of carrier protein was present. Based on this, a quantitative assay was developed using either normal plasma or F.XII dilutions in F.XII-deficient plasma as standards. The measurement of F.XII antigen by immunoblotting was reproducible and gave values similar to those obtained by radial immunodiffusion. Two normal plasma pools contained 26 and 29 μ/ml of F.XII according to the immunoblotting assay. Compared to other immunoassays, immunoblotting has the advantage of directly estimating the apparent molecular weight (MW) of the protein of interest. Thus, we could confirm the normal apparent MW (80,000) of a F.XII-like molecule previously isolated from a cross reacting material (CRM)-positive F.XII-deficient plasma. None of eight CRM-negative F.XII-deficient plasmas showed an 80,000 MW immunoreactive molecule. However, five of these eight plasmas had a faint autoradiographic band at 115,000 MW that was similarly seen in only three out of 43 individual normal plasmas. The nature of this 115,000 MW band remains to be defined.  相似文献   
24.

Background  

Shoulder disorders are a common health problem in western societies. Several treatment protocols have been developed for the clinical management of persons with shoulder pain. However available evidence does not support any protocol as being superior over others. Systematic reviews provide some evidence that certain physical therapy interventions (i.e. supervised exercises and mobilisation) are effective in particular shoulder disorders (i.e. rotator cuff disorders, mixed shoulder disorders and adhesive capsulitis), but there is an ongoing need for high quality trials of physical therapy interventions. Usually, physical therapy consists of active exercises intended to strengthen the shoulder muscles as stabilizers of the glenohumeral joint or perform mobilisations to improve restricted mobility of the glenohumeral or adjacent joints (shoulder girdle). It is generally accepted that a-traumatic shoulder problems are the result of impingement of the subacromial structures, such as the bursa or rotator cuff tendons. Myofascial trigger points (MTrPs) in shoulder muscles may also lead to a complex of symptoms that are often seen in patients diagnosed with subacromial impingement or rotator cuff tendinopathy. Little is known about the treatment of MTrPs in patients with shoulder disorders.  相似文献   
25.
We report here the antiproteolytic and antihemorrhagic properties of triterpenoid saponin inhibitors, named macrolobin-A and B, from Pentaclethra macroloba, against Bothrops snake venoms. The inhibitors were able to neutralize the hemorrhagic, fibrin(ogen)olytic, and proteolytic activities of class P-I and P-III metalloproteases isolated from B. neuwiedi and B. jararacussu venoms. Clotting and fibrinogenolytic activities induced by snake venoms and isolated thrombin-like enzymes were partially inhibited. Furthermore, the potential use of these inhibitors to complement antivenom therapy as an alternative treatment and/or used as molecular models for development of new therapeutical agents in the treatment of snake bite envenomations needs to be evaluated in future studies.  相似文献   
26.
Clinical practice guidelines have been proposed to significantly reduce the gap between available scientific evidence and clinical practice. Evidence-based guidelines are also being produced at an ever-increasing pace. However, guidelines do not implement themselves, and the research to support implementation does not provide straightforward answers. What works in one setting does not necessarily work in another. In short, guideline implementation and change of practice is complex and messy. The purpose of this article is to discuss the implementation of clinical practice guidelines using the Promoting Action on Research Implementation in Health Services framework. More specifically, 3 key components are highlighted: (1) the evidence base for guideline recommendations, (2) the clinical context where guidelines are to be implemented, and (3) the nature of facilitation needed to ensure a successful change process. An overview of the literature in the field is provided, and the authors' experiences are shared, and a few recommendations are tentatively provided.  相似文献   
27.
Intervention studies aimed at promoting increased physical activity have been trialled in many different settings including primary care, worksites and the community. Churches are also potential settings for physical activity promotion. However, little is known about the effectiveness of this setting for promoting physical activity, particularly in Australia. The purpose of this study was to evaluate the effectiveness of a mind, body and spiritually based health promotion program in increasing physical activity and promoting mental and spiritual health. Nineteen women completed the 8-week intervention, and 30 women in a non-health related 8-week program at the same church comprised a comparison group. Pre- and post-program surveys assessed outcome measures. Between-group differences over time were examined using one-way MANOVA's. Physical activity was higher in the intervention group than the comparison group. In contrast to the comparison group, both mental health (depression symptoms) and spiritual health improved significantly more among intervention participants. The data highlight the potential for a church-based setting and holistic approach to health promotion as a successful means of increasing physical activity and promoting mental and spiritual health among Australian women.  相似文献   
28.
Background. Accepted practices of informed consent often result in suboptimal patient understanding of research studies.Methods. This pilot study aimed to assess trial-specific tailored materials, compared to a widely used generic booklet about clinical trials, randomly assigned to 118 candidates for cancer clinical trials. Study outcomes were: satisfaction with decision-making; satisfaction with materials; and subjective understanding of the clinical trial.Results. There were no major differences between groups. Participants rated tailored materials higher as a useful reference.Conclusions. Trial-specific materials hold utility for reference during clinical trials. Studies of informed consent are feasible, although important factors limit research.  相似文献   
29.
Semi-structured interviews were conducted with a cohort of 22 test applicants who requested Huntington's disease (HD) predictive testing in South Wales, and a random sample of 32 non-requesters, drawn from the South Wales HD register. Apart from identifying differences between the groups, the study afforded the opportunity to listen, at length, to at-risk individuals' accounts of living at risk and their thoughts about predictive testing and genetic services. Emergent themes included difficulties in family communication and the uncertainties inherent in being at risk and undergoing testing. Important factors in decision making about testing were: moral imperatives to clarify one's genetic status; views about the controllability of the future; family attitudes and norms; and the impact of a test result on family members. At-risk individuals' perceptions of the genetics service were that contact with the service would result in pressure to be tested and a need for test applicants to present a favourable view of coping capacities to secure testing. In addition, there was an expectation of ongoing contact with HD families at the initiative of the service providers. Implications of the findings for the way in which predictive testing services are structured and introduced to the at-risk population are discussed.  相似文献   
30.
Regulation of T cell-dependent immune responses is mediated in part by bone marrow-derived antigen presenting cells (APC) that (a) process and present antigens which engage the T cell receptor and (b) secrete cytokines that influence the threshold of T cell activation. The anterior chamber of the eye is lined by the corneal endothelium (which rests on a stroma and epithelium that is devoid of class II MHC + APC) and iris/ciliary body (which contain significant numbers of bone marrow-derived cells, one third of which are class II MHC +). When tested in vitro, these potential APCs fail to present antigens in a form that activates T cells. Moreover, iris/ciliary body cells actually suppress activation of T cells exposed to antigens on conventional APC. In addition, aqueous humor under normal circumstances contains factors (one of which is TGFB) that are potent inhibitors of antigen-driven T cell activation, but spare other aspects of T cell function. Evidence suggests that the bone marrow-derived cells in iris/ciliary body are the source of this factor. Thus, the anterior chamber contains powerful forces that can prevent induction and can suppress expression of T cell mediated immunity. It is proposed that these forces are responsible for immunologic privilege and anterior chamber associated immune deviation, and for suppressing pathologic proliferation and inflammation in the anterior segment of the eye.  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