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   8054篇
  免费   496篇
  国内免费   55篇
耳鼻咽喉   74篇
儿科学   288篇
妇产科学   181篇
基础医学   1320篇
口腔科学   108篇
临床医学   624篇
内科学   1990篇
皮肤病学   179篇
神经病学   818篇
特种医学   231篇
外科学   661篇
综合类   26篇
预防医学   685篇
眼科学   156篇
药学   622篇
中国医学   37篇
肿瘤学   605篇
  2023年   56篇
  2022年   171篇
  2021年   284篇
  2020年   166篇
  2019年   231篇
  2018年   247篇
  2017年   204篇
  2016年   208篇
  2015年   247篇
  2014年   333篇
  2013年   411篇
  2012年   646篇
  2011年   650篇
  2010年   330篇
  2009年   277篇
  2008年   500篇
  2007年   561篇
  2006年   520篇
  2005年   478篇
  2004年   445篇
  2003年   396篇
  2002年   384篇
  2001年   61篇
  2000年   48篇
  1999年   62篇
  1998年   70篇
  1997年   66篇
  1996年   52篇
  1995年   53篇
  1994年   35篇
  1993年   38篇
  1992年   35篇
  1991年   23篇
  1990年   33篇
  1989年   21篇
  1988年   26篇
  1987年   22篇
  1986年   18篇
  1985年   9篇
  1984年   12篇
  1983年   14篇
  1981年   13篇
  1980年   13篇
  1978年   11篇
  1977年   11篇
  1976年   10篇
  1975年   14篇
  1974年   12篇
  1971年   9篇
  1970年   10篇
排序方式: 共有8605条查询结果,搜索用时 609 毫秒
91.
92.
Aim. To study any discriminative properties of SF-36 and QQL-EPM in stable and non-controlled moderate asthmatic patients. Methods. A total of 63 asthmatic patients were assessed regarding asthma symptoms, FEV1 % predicted value, PEF, ED visits and hospitalizations, QQL-EPM and SF-36 questionnaires. Results. QQL-EPM highlighted significance in all domains to distinguish stable from non-controlled patients (p = 0.0001) while SF-36 was only significant in 3 of its 7 domains (p = 0.009). Conclusion. The study showed that the specific quality of life questionnaire for asthma (QQL-EPM) demonstrates better discriminative properties that characterize asthma control when compared with the more generic SF-36 questionnaire.  相似文献   
93.
94.
95.
Age-related memory decline appears to be due to impaired recollection whereas familiarity may be intact. An intervention was therefore designed with the aim of optimising use of this intact sense of familiarity. A continuous face recognition paradigm was used which required detection of repeats in a long series. The experimental intervention consisted of immediate feedback on response accuracy and avoidance of errors by discouraging guessing.

Experimental and control interventions were compared by recruiting 40 people aged under 30 years or over 60 years for six 45-minute training sessions. The elderly participants initially showed a more lax response criterion than young people but the experimental intervention reversed this effect so that by the end of training the elderly participants were less prone to false alarms than the younger participants. However, there was only limited evidence of generalisation of this training effect to other memory tasks and no effect on recognition sensitivity.

This study demonstrates that combined feedback and errorless learning allow elderly people to adjust their response criterion during recognition memory tasks. Taken together with previous encouraging studies, it seems that this training approach might have potential as a therapy for age-related memory impairment. However this would require development of additional methods to enhance generalisation beyond trained tasks and to elicit improvements in sensitivity as well as reduction of false alarms. The separate contributions of feedback and errorless learning also need to be investigated.  相似文献   
96.
Friction Stir Welding (FSW) is a solid-state joining process; i.e., no melting occurs. The welding process is promoted by the rotation and translation of an axis-symmetric non-consumable tool along the weld centerline. Thus, the FSW process is performed at much lower temperatures than conventional fusion welding, nevertheless it has some disadvantages. Laser Assisted Friction Stir Welding (LAFSW) is a combination in which the FSW is the dominant welding process and the laser pre-heats the weld. In this work FSW and LAFSW tests were conducted on 6 mm thick 5754H111 aluminum alloy plates in butt joint configuration. LAFSW is studied firstly to demonstrate the weldability of aluminum alloy using that technique. Secondly, process parameters, such as laser power and temperature gradient are investigated in order to evaluate changes in microstructure, micro-hardness, residual stress, and tensile properties. Once the possibility to achieve sound weld using LAFSW is demonstrated, it will be possible to explore the benefits for tool wear, higher welding speeds, and lower clamping force.  相似文献   
97.
Objective: Mucociliary clearance sustains a baseline functionality and an “on demand” capability to upregulate clearance upon irritant exposure involving mucus hypersecretion and accelerated ciliary beat frequency (CBF) modulated by nitric oxide (NO). This study characterized these elements as well as cellular and exogenous NO concentrations subsequent to a single exposure to tobacco smoke (TS) or e-cigarette vapor (EV) on cultured human airway epithelium.

Materials and methods: Air–liquid interface (ALI) airway epithelial cultures per nonsmoking human subjects were subjected to single TS or EV exposures. Measures of ciliary function and secretion were performed and cellular and exogenous NO concentrations under control and experimental conditions were assessed.

Results: Both TS and EV exposures resulted similar patterns of decline in CBF within 1?min of the completion of exposure followed by a gradual return often exceeding baseline within 1?h. Post-exposure examination of exposed cultures suggested morphologic differences in secretory function relative to controls. The relative NO concentrations of TS and EV chamber air were sharply different with EV NO being only slightly elevated relative to cellular NO production.

Discussion and conclusions: Epithelial remodeling and mucociliary dysfunction have been clearly associated with TS exposure. However, information contrasting epithelial structure/function following a single acute TS or EV exposure is limited. This study demonstrates a similar pattern of epithelial response to acute TS or EV exposure. Inasmuch as NO may contribute to an inflammatory milieu and generation of toxic metabolites, it is plausible that recurrent exposures over time may be contributory to chronic pathologies.  相似文献   
98.
This article contains a review of the current status of remote monitoring and follow-up involving cardiac pacing devices and of the latest developments in cardiac resynchronization therapy. In addition, the most important articles published in the last year are discussed.  相似文献   
99.
100.
To explore attitudes of physicians attending births in the public and private sectors and at the managerial level toward cesarean birth in Nicaragua. A qualitative study was conducted consisting of four focus groups with 17 physicians and nine in-depth interviews with decision-makers. Although study participants listed many advantages of vaginal birth and disadvantages of cesarean birth, they perceived that the increase in the cesarean birth rate in Nicaragua has resulted in a reduction in perinatal morbidity and mortality. They ascribed high cesarean birth rates to a web of interrelated provider, patient, and health system factors. They identified five actions that would facilitate a reduction in the number of unnecessary cesarean operations: establishing standards and protocols; preparing women and their families for labor and childbirth; incorporating cesarean birth rate monitoring and audit systems into quality assurance activities at the facility level; strengthening the movement to humanize birth; and promoting community-based interventions to educate women and families about the benefits of vaginal birth. Study participants believe that by performing cesarean operations they are providing the best quality of care feasible within their context. They do not perceive problems with their current practice. The identified causes of unnecessary cesarean operations in Nicaragua are multifactorial, so it appears that a multi-layered strategy is needed to safely reduce cesarean birth rates. The recent Nicaraguan Ministry of Health guidance to promote parto humanizado (“humanization of childbirth”) could serve as the basis for a collaborative effort among health care professionals, government, and consumer advocates to reduce the number of unnecessary cesarean births in Nicaragua.  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