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   26079篇
  免费   1511篇
  国内免费   142篇
耳鼻咽喉   257篇
儿科学   655篇
妇产科学   523篇
基础医学   3824篇
口腔科学   1205篇
临床医学   2312篇
内科学   6153篇
皮肤病学   677篇
神经病学   2336篇
特种医学   604篇
外科学   2430篇
综合类   55篇
一般理论   10篇
预防医学   2385篇
眼科学   482篇
药学   1746篇
中国医学   115篇
肿瘤学   1963篇
  2024年   34篇
  2023年   268篇
  2022年   613篇
  2021年   1065篇
  2020年   639篇
  2019年   850篇
  2018年   977篇
  2017年   679篇
  2016年   795篇
  2015年   875篇
  2014年   1153篇
  2013年   1484篇
  2012年   2300篇
  2011年   2388篇
  2010年   1264篇
  2009年   1043篇
  2008年   1780篇
  2007年   1703篇
  2006年   1575篇
  2005年   1443篇
  2004年   1284篇
  2003年   1081篇
  2002年   941篇
  2001年   158篇
  2000年   124篇
  1999年   139篇
  1998年   146篇
  1997年   127篇
  1996年   94篇
  1995年   74篇
  1994年   65篇
  1993年   64篇
  1992年   60篇
  1991年   52篇
  1990年   52篇
  1989年   42篇
  1988年   39篇
  1987年   26篇
  1986年   51篇
  1985年   37篇
  1984年   38篇
  1983年   23篇
  1982年   19篇
  1981年   14篇
  1980年   5篇
  1979年   8篇
  1978年   9篇
  1977年   5篇
  1974年   4篇
  1973年   4篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
22.
The objective of the study was to describe the implementation of measures for preventing tobacco consumption developed in the Catalan Network of Smoke-free Hospitals. Information from 25 hospitals that are actively involved in the Catalan Network of Smoke-free Hospitals (April 2004) was used. The degree of implementation of the Smoke-free Hospitals Project was analysed by means of the Self-Audit Questionnaire of the European Network for Smoke-free Hospitals; each hospital was analysed globally and according to the duration of its Network membership (<1 year: implementation stage; > or =1 year: consolidation stage). In terms of global indicators, there were high levels of commitment (64.8%), communication (74.7%), tobacco control (77.4%) and implementation of smoke-free environments (81.0%). A lower degree of implementation (<50%) was found in education and training, health promotion and healthy workplaces. According to the duration of Network membership, significant differences were observed for communication, environment, healthy workplaces and follow-up. Deficits were observed in areas such as specialist training and cessation support, and further input is required here. By identifying areas needing attention, providing a guide for policy development and by administering it periodically, one can ensure that progress is kept on track.  相似文献   
23.
T cells are known to develop a critical role in the pathogenesis of atopic dermatitis (AD) and bronchial asthma. T cells involved in AD express the skin homing receptor CLA, but no lung homing receptor has been identified in bronchial asthma. We compared different cell markers and the cytokine production in T cells from children with AD or bronchial asthma. We studied the involvement of CLA+ and CLA- T-cell subpopulations in these diseases. We studied 20 children with acute AD lesions, 15 with mild persistent asthma, and 15 non-atopic controls. All patients were sensitized to house dust mite (DP) and evaluated during the acute phase. Total and specific IgE were measured by immunoassay and the expression of different cell markers and the cytokine production was analyzed by flow cytometry in peripheral blood mononuclear cells. Total IgE was significantly higher in AD children and IgE to DP in the asthmatic children. There was a significant increase in CD25+ CD4+ cells in asthmatic children and in HLA-DR+ CD4+ and HLA-DR+ CD8+ cells in AD. In the CD4+ subsets, there was an increase in IL-13, IL-5 and TNF-alpha in AD compared to controls, a decrease in IFN-gamma in asthmatic children compared to controls, and an increase in IL-13, IL5, IL2, TNF-alpha, and IFN-gamma in the AD compared to asthmatic children. Changes in cytokine production were mainly detected in CLA+ cells in AD and in CLA- cells in asthma. Differences exist in total and specific IgE, activation markers, and cytokine patterns between AD children and children with asthma, with the former expressing a Th2 pattern whereas in asthmatic children we only detected a decrease in IFN-gamma. Moreover, the subpopulations (CLA+ vs. CLA-) expressing these changes were different, indicating that the underlying mechanisms in the two diseases are not exactly the same.  相似文献   
24.
25.
OBJECTIVE: The objective of this study is to evaluate the inflammatory response caused by endovascular stents in the treatment of aortic aneurysms. METHODS: Twenty-five patients underwent endovascular stent treatment from March through December 2005. The evolution of mediators (sedimentation velocity, C reactive protein, interleukin-6, interleukin-8, tumor necrosis factor-alpha, intercellular adhesion molecule-1, l-selectin), inflammatory cells (leukocytes, lymphocytes, platelets), serum creatinine and body temperature within preoperative period and in the following postoperative periods--1, 6, 24 and 48 h, 7 days, 1-3 months, was analyzed. In order to achieve statistic significance, Friedman test and Wilcoxon test were used, with index of significance of 5% (p<0.05). RESULTS: Peak values of sedimentation velocity, C reactive protein and interleukin-6 were observed at 7 days (p<0.0001), 48 h (p<0.0001) and 24h (p<0.0001), respectively. Tumor necrosis factor-alpha and interleukin-8 did not show statistically significant variability during the entire follow-up. In terms of intercellular adhesion molecule-1 and l-selectin, their expressive values were found in late phase of follow-up, although without statistical significance. Elevation of leukocytes count occurred in premature phase of follow-up (p<0.0001), while lymphocyte and platelet count occurred in a late phase of follow-up (p<0.0001). Serum levels of creatinine did not show significant variability during follow-up. The period between 24 and 48 h corresponded to major frequency for fever (p<0.0001). CONCLUSION: Individual mediators analysis and inflammatory cells demonstrated variability of their values during postoperative follow-up. This could help in the analysis of the inflammatory response evolution caused by endovascular stent treatment for aortic aneurysms in premature and late phases after implantation of the vascular prosthesis.  相似文献   
26.
Our objective was to evaluate the frequency of neoplastic and preneoplastic skin lesions in Parkinson's disease (PD) patients when compared with an aged-matched population. We performed a cross-sectional survey in PD patients and in an age-matched control group. Patients and controls were examined by a movement disorder specialist and a dermatologist. 150 PD patients and 146 controls were included. Thirty-five PD patients (23.3%) presented skin lesions that could be classified as neoplastic or preneoplastic vs. 20 subjects in the control group (13.7%) (OR 95%, CI 1.92 [1.05, 3.51]). However, this difference lost statistical significance when adjusted for gender (recruitment of controls was matched just for age with an over representation of males in the PD group). Twenty-nine PD patients (19%) presented actinic keratosis and basal cell carcinoma was diagnosed in 4 patients (3%). Although nonconclusive, our results are in agreement with previous studies suggesting an increased risk of skin cancer in PD patients. The frequency of actinic keratosis in PD patients and the associated risk to develop melanoma recommends its screening in future epidemiological studies.  相似文献   
27.
This article presents the revision process, major innovations, and clinimetric testing program for the Movement Disorder Society (MDS)-sponsored revision of the Unified Parkinson's Disease Rating Scale (UPDRS), known as the MDS-UPDRS. The UPDRS is the most widely used scale for the clinical study of Parkinson's disease (PD). The MDS previously organized a critique of the UPDRS, which cited many strengths, but recommended revision of the scale to accommodate new advances and to resolve problematic areas. An MDS-UPDRS committee prepared the revision using the recommendations of the published critique of the scale. Subcommittees developed new material that was reviewed by the entire committee. A 1-day face-to-face committee meeting was organized to resolve areas of debate and to arrive at a working draft ready for clinimetric testing. The MDS-UPDRS retains the UPDRS structure of four parts with a total summed score, but the parts have been modified to provide a section that integrates nonmotor elements of PD: I, Nonmotor Experiences of Daily Living; II, Motor Experiences of Daily Living; III, Motor Examination; and IV, Motor Complications. All items have five response options with uniform anchors of 0 = normal, 1 = slight, 2 = mild, 3 = moderate, and 4 = severe. Several questions in Part I and all of Part II are written as a patient/caregiver questionnaire, so that the total rater time should remain approximately 30 minutes. Detailed instructions for testing and data acquisition accompany the MDS-UPDRS in order to increase uniform usage. Multiple language editions are planned. A three-part clinimetric program will provide testing of reliability, validity, and responsiveness to interventions. Although the MDS-UPDRS will not be published until it has successfully passed clinimetric testing, explanation of the process, key changes, and clinimetric programs allow clinicians and researchers to understand and participate in the revision process.  相似文献   
28.
29.
30.
Twenty patients with AIDS who had intracranial lesions underwent both brain biopsy and cerebro-spinal fluid (CSF) examination to compare histological diagnosis with the polymerase chain reaction (CSF-PCR) for the identification of infectious agents. CSF-PCR was performed for herpes simplex virus, varicella zoster virus, cytomegalovirus (CMV), JC virus (JCV), Epstein-Barr virus (EBV), Toxoplasma gondii and Mycobacterium tuberculosis. A definitive diagnosis was obtained by brain biopsy in 14 patients (2 with astrocytoma, 12 with brain infection). CSF-PCR was positive for EBV DNA in 3 of 3 cases of primary cerebral lymphoma, positive for JCV DNA in 6 of 7 biopsy-proven (and one autopsy-proven) cases of progressive multifocal leukoencephalopathy (PML). CSF-PCR was positive for CMV DNA in one biopsy-proven and one autopsy-proven case of CMV encephalitis (the former also had PML) and positive for M. tuberculosis DNA in one case of tuberculous encephalitis. None of the five toxoplasmic encephalitis cases (one definite, four presumptive) were T. gondii DNA positive. There was close correlation between histology and CSF-PCR for CMV encephalitis, PML and PCL. Antitoxoplasma therapy affected the sensitivity of both histological and CSF-PCR methods. Received: 8 November 1995 Received in revised form: 9 July 1996 Accepted: 19 July 1996  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