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   18730篇
  免费   999篇
  国内免费   45篇
耳鼻咽喉   249篇
儿科学   777篇
妇产科学   288篇
基础医学   2387篇
口腔科学   314篇
临床医学   1282篇
内科学   5106篇
皮肤病学   725篇
神经病学   1470篇
特种医学   322篇
外科学   2735篇
综合类   78篇
一般理论   5篇
预防医学   1510篇
眼科学   474篇
药学   1082篇
中国医学   56篇
肿瘤学   914篇
  2023年   120篇
  2022年   95篇
  2021年   417篇
  2020年   196篇
  2019年   490篇
  2018年   746篇
  2017年   438篇
  2016年   400篇
  2015年   442篇
  2014年   508篇
  2013年   731篇
  2012年   1224篇
  2011年   1345篇
  2010年   738篇
  2009年   548篇
  2008年   1087篇
  2007年   1126篇
  2006年   1164篇
  2005年   1144篇
  2004年   1007篇
  2003年   1067篇
  2002年   963篇
  2001年   648篇
  2000年   791篇
  1999年   594篇
  1998年   96篇
  1997年   62篇
  1996年   66篇
  1995年   55篇
  1994年   47篇
  1993年   34篇
  1992年   205篇
  1991年   183篇
  1990年   155篇
  1989年   110篇
  1988年   110篇
  1987年   95篇
  1986年   79篇
  1985年   85篇
  1984年   38篇
  1983年   39篇
  1982年   15篇
  1979年   27篇
  1978年   17篇
  1974年   15篇
  1973年   19篇
  1972年   14篇
  1970年   20篇
  1969年   16篇
  1968年   23篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
31.
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   
32.
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   
33.
The production of chlamydospores is a diagnostic tool used to identify Candida albicans; these structures also represent a model for morphogenetic research. The time required to produce them with standard methods is 48-72 hours in rice meal agar and tensoactive agents. This time can be shorted using liquid media such as cornmeal broth (CMB) and dairy supplements. Five media were tested: CMB plus 1% Tween-80, CMB plus 5% milk, CMB plus 5% milk serum, milk serum, and milk serum plus 1% Tween-80, under different incubation conditions: at 28 degrees C and 37 degrees C in a metabolic bath stirring at 150 rpm, and at 28 degrees C in a culture stove. The reading time points were established at 8 and 16 hours. The best results were obtained at 16 hours with CMB plus 5% milk under incubation at 28 degrees C and stirring at 150 rpm. The next most efficient methods were CMB plus 5% milk serum and CMB plus 1% Tween-80, under the same incubation conditions. The other media were ineffective in producing chlamydospores. The absence of stirring at 28 degrees C prevented the formation of chlamydospores within the set time points, and incubation at 37 degrees C decreased their production. This paper reports that the time to form C. albicans chlamydospores can be reduced.  相似文献   
34.
35.
36.

Objectives  

This study was designed to assess the prevalence of adverse drug reactions (ADRs) in the internal medicine wards of two teaching Hospitals, identify the most common ADRs, the principal medications involved, and determine the risk factors implicated in the occurrence of such ADRs.  相似文献   
37.
 NADPH-diaphorase positive (NDP) neurons and nerve fibers were found in the spinal dorsal horn (DH) and sensory ganglia of the turtle Chrysemys d’orbigny. Three well-defined types of NDP neurons were found in the DH: (a) elongated nerve cells with two radially arranged dendritic branches, (b) neurons with rostro-caudal dendritic branches, (c) bitufted neurons with two, practically symmetric branches that project to the ipsilateral and contralateral dorsal horns. A combination of the techniques that reveal NADPH-diaphorase activity with the horseradish peroxidase transganglionic labeling of the dorsal root collaterals, suggested that NDP neurons of the DH are second-order cells of the spinal sensory pathway. NDP neurons were also found in the spinal sensory ganglia at all metameric levels. Our findings indicate that the DH of turtles, like that of mammals, contains both the enzymatic machinery and the neural connections required to postulate the participation of nitric oxide in ”plastic phenomena” such as hyperalgesia and central sensitization. Two other alternatives or complementary hypotheses are discussed: (a) NDP neurons in the DH and sensory ganglia may represent specific cell populations involved in the processing of sensory visceral information; (b) NADPH-diaphorase reactivity may indicate sustained levels of neuronal activity. Received: 12 February 1996 / Accepted: 2 August 1996  相似文献   
38.
Estrogen receptors in the external anal sphincter   总被引:1,自引:0,他引:1  
Inasmuch as anal competence in women is reduced after the age of 50 years, it may be dependent on effects of estrogens. In this study, samples of the external anal sphincter were analyzed for the presence of estrogen receptors and were found to be present at a median concentration of 5.0 fmol per milligram of protein (range, 1.9 to 13) in women (n = 7), and 1.1 fmol per milligram of protein (range, 0 to 3.2) in men (n = 7). These findings are of interest with regard to the treatment of idiopathic anal incontinence.  相似文献   
39.
PURPOSE: The purposes of this study were to evaluate self-esteem over 3 years in the 469 myopic children participating in the Correction of Myopia Evaluation Trial (COMET), and to examine its relationship with lens assignment (progressive addition lenses [PALs] vs. single-vision lenses [SVLs]), myopia progression, and several other ocular and demographic characteristics. METHODS: Data collection included refractive error measurements, child-reported visual symptoms, attitude toward glasses, adherence, and self-esteem as measured by the Self-Perception Profile for Children (SPPC). A two-way analysis of variance (treatment group x time) was performed to examine whether PAL and SVL wearers differed in self-esteem over time. Multiple regression analyses were used to evaluate associations between self-esteem at follow-up and relevant factors identified by univariate analyses. RESULTS: Regardless of lens assignment or myopia progression, COMET children reported moderate to high levels of self-esteem at follow-up in the areas of scholastic and athletic competence, physical appearance, social acceptance, behavioral conduct, and global self-worth. Mean scores ranged from 2.87 (+/- 0.68) on athletic competence to 3.40 (+/- 0.56) on global self-worth. Self-esteem changed significantly (p < 0.05) over 3 years in the domains of scholastic competence, social acceptance, and physical appearance. Self-esteem at follow-up was associated with visual symptoms, attitude toward glasses, age, gender, and ethnicity. CONCLUSIONS: Lens assignment and myopia progression were not associated with self-esteem in the COMET cohort. These children had high levels of self-esteem, suggesting that having myopia does not negatively impact self-esteem. Follow-up reports will monitor self-esteem and related factors in this cohort of myopic children over the course of adolescence and early adulthood.  相似文献   
40.
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