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   99597篇
  免费   29289篇
  国内免费   1124篇
耳鼻咽喉   2412篇
儿科学   2660篇
妇产科学   2367篇
基础医学   2535篇
口腔科学   5130篇
临床医学   25893篇
内科学   25289篇
皮肤病学   3328篇
神经病学   12155篇
特种医学   3832篇
外科学   18388篇
综合类   113篇
现状与发展   40篇
预防医学   13206篇
眼科学   2109篇
药学   1122篇
中国医学   13篇
肿瘤学   9418篇
  2024年   746篇
  2023年   5080篇
  2022年   1176篇
  2021年   2857篇
  2020年   5394篇
  2019年   2116篇
  2018年   7016篇
  2017年   7385篇
  2016年   7979篇
  2015年   8063篇
  2014年   10514篇
  2013年   12217篇
  2012年   3874篇
  2011年   3632篇
  2010年   6866篇
  2009年   9144篇
  2008年   3542篇
  2007年   2454篇
  2006年   3604篇
  2005年   2232篇
  2004年   1576篇
  2003年   1239篇
  2002年   1132篇
  2001年   1815篇
  2000年   1136篇
  1999年   1682篇
  1998年   2097篇
  1997年   1916篇
  1996年   1962篇
  1995年   1698篇
  1994年   1090篇
  1993年   919篇
  1992年   744篇
  1991年   639篇
  1990年   516篇
  1989年   529篇
  1988年   513篇
  1987年   379篇
  1986年   361篇
  1985年   294篇
  1984年   250篇
  1983年   297篇
  1982年   226篇
  1981年   196篇
  1980年   122篇
  1978年   121篇
  1977年   117篇
  1976年   83篇
  1974年   71篇
  1972年   70篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
Objective: To determine the effect of indwelling versus intermittent feeding tube placement on weight gain, apnea, and bradycardia in premature neonates.
Design: Eligible subjects were assigned randomly to either feeding tube method. Each subject was followed for 6 days.
Setting: The study was conducted in a secondary level neonatal intensive-care unit (NICU), a tertiary level NICU in a perinatal center, and a tertiary level NICU in a referral center.
Patients/Participants: Neonates who were 24–34 weeks gestational age, developmentally appropriate for gestational age, medically stable, on full enteral feedings through an orogastric or a nasogastric tube, and not fluid restricted. Ninety-three neonates were enrolled-49 in the indwelling group and 44 in the intermittent group. Nine neonates did not complete the study.
Interventions: Nasogastric indwelling feeding tubes were placed and left in site for up to 3 days. Orogastric intermittent feeding tubes were placed for each feeding and removed at completion of the feeding.
Main outcome measures: Weight gain, apnea, and bradycardia. Results: Members of both groups had similar demographic characteristics, clinical problems, and nutritional intake. No statistical differences were found between the two groups in weight gain or episodes of apnea and bradycardia.
Conclusions: There were no statistically or clinically significant differences between the two groups. The intermittent method of feeding is more expensive. Because no clinical differences were found, the type of tube placement chosen for feeding the premature infant may be based on economics.  相似文献   
73.
In the context of an interview study concerned with self-determination in psychiatric patients, this paper describes the preconditions for and consequences of self-determination from the point of view of psychiatric patients themselves. The data were collected in semi-structured interviews with long-term psychiatric patients ( n =72) and analysed using the method of content analysis. Responses on the preconditions for self-determination were grouped into three categories: firstly, there were those who said that reference to self-determination in the case of psychiatric patients is nonsense; secondly, there were those who said that self-determination requires no preconditions; and thirdly, there were those who said that there are certain preconditions, such as the ability to think and make decisions, activity, obedience, and illness. Both positive and negative consequences were identified in situations where self-determination is maintained, but only negative consequences in situations where self-determination is lost. On the basis of these tentative results, self-determination seemed to be relevant in psychiatric nursing. We are continuing to develop and test an instrument for the evaluation of the opportunity for self-determination in clinical practice.  相似文献   
74.
75.
Background. The modified Fontan procedure separates the systemic and pulmonary circulations in patients born with a functional single ventricle. Delayed recovery is frequently observed after this procedure. It was our hypothesis that complement activation or cytokine generation may contribute to the pathophysiology of this problem.

Methods. We measured activated complement C3, thromboxane B2, interleukin-6, and tumor necrosis factor- levels by immunoassay in 16 patients undergoing Fontan procedure. Patient plasma samples were obtained preoperatively, on initiation of cardiopulmonary bypass, after administration of protamine, and 1, 4, 8, and 24 hours postoperatively.

Results. There was no early or late mortality in this cohort of patients. Low cardiac output developed in 3 of 16 patients, and pleural effusions developed in 5. The median length of hospital stay was 9 days. Activated complement C3 levels increased from a baseline of 1,486 ± 564 to 4,600 ± 454 ng/mL after cardiopulmonary bypass and administration of protamine, and returned to baseline by 24 hours. The level of interleukin-6 increased from 42 ± 32 to 176 ± 22 pg/mL and at 24 hours remained elevated at 71 ± 15 pg/mL. Neither thromboxane B2 nor tumor necrosis factor- levels increased significantly.

Conclusions. The data demonstrate threefold to fourfold increases in activated complement C3 and interleukin-6, indicating that both humoral and cellular systems are affected. It is our conclusion that complement and cytokine activation may contribute to the delayed recovery observed after Fontan procedure.  相似文献   

76.
The new complaints procedures which local authority social services departments have been required to introduce represent an important mechanism for managing the change of culture associated with recent community care reforms. They also represent a new genre in mechanisms of redress for welfare recipients. This paper reports the findings of a study which has observed considerable diversity in the ways in which local authorities are interpreting the nature and purposes of the new procedures and, in particular, the functions of review panels established under those procedures. Variations in the composition of panels, in the style of review panel proceedings, in perceptions of the panels' powers, and in the ways that complaints and complainants are constituted are all discussed. Attention is drawn to four competing interpretations of the review panels' role and to the need for these to be clarified and prioritised.  相似文献   
77.
Surgical services are an important part of modern health care, but providing them to isolated rural citizens is especially difficult. Public policy initiatives could influence the supply, training, and distribution of surgeons, much as they have for rural primary care providers. However, so little is known about the proper distribution of surgeons, their contribution to rural health care, and the safety of rural surgery that policy cannot be shaped with confidence. This study examined the volume and complexity of inpatient surgery in rural Washington state as a first step toward a better understanding of the current status of rural surgical services. Information about rural surgical providers was obtained through telephone interviews with administrators at Washington's 42 rural hospitals. The Washington State Department of Health's Commission Hospital Abstract Recording System (CHARS) data provided a count of the annual surgical admissions at rural hospitals. Diagnosis-related group (DRG) weights were used to measure complexity of rural surgical cases. Surgical volume varied greatly among hospitals, even among those with a similar mix of surgical providers. Many hospitals provided a limited set of basic surgical services, while some performed more complex procedures. None of these rural hospitals could be considered high volume when compared to volumes at Seattle hospitals or to research reference criteria that have assessed volume-outcome relationships for surgical procedures. Several hospitals had very low volumes for some complex procedures, raising a question about the safety of performing them. The leaders of small rural hospitals must recognize not only the fiscal and service benefits of surgical services--and these are considerable--but also the potentially adverse effect of low surgical volume on patient outcomes. Policies that encourage the proper training and distribution of surgeons, the retention of basic rural surgical services, and the rational regionalization of complex surgery are likely to enhance the convenience and safety of surgery for rural citizens.  相似文献   
78.
The performance of area health education center (AHEC)-stimulated programs and decentralized education for medicine is not well understood. The Statewide Education Activities for Rural Colorado's Health (SEARCH)/AHEC project at the University of Colorado School of Medicine was examined to determine if the program had an effect on the practice location of its graduates. Practice location and specialty of graduates of the University of Colorado School of Medicine (UCSOM) classes 1980-1985 were compared for students who had participated in decentralized SEARCH/AHEC experiences versus students who had not. The majority of the graduates were practicing out of state in 1990. Non-Colorado doctors were more often practicing in rural (non-metropolitan statistical area [MSA]) counties and in towns of fewer than 2,500, 5,000 and 10,000 residents, respectively. In addition, of the 251 active patient care physicians practicing in Colorado communities of fewer than 10,000 in non-MSA counties in 1986, those who precepted UCSOM students on SEARCH rotations were more likely to have remained in their same practice location in 1992 (77.8% versus 62.1% for those who had not precepted students). This analysis of both student and preceptor practice patterns documents the value of decentralized medical education in addressing the geographic and specialty maldistribution of physicians. These results have important policy implications for funding medical education programs.  相似文献   
79.
A controversy exists regarding the classification of nonorganic failure to thrive within the psychiatric nomenclature. There are a number of DSM-III-R diagnoses that may be applied to NOFTT, including Reactive Attachment Disorder of Infancy (RADI) and Major Depressive Disorder (MDD). The behaviors characteristic of NOFTT are symptomatic of depression, and are similar to those exhibited by infants with anaclitic depression as well as those of the adult with depression. The correspondence of the behaviours of NOFTT and the DSM-III-R criteria for Major Depression are reviewed, as are the conceptual and therapeutic reasons to view NOFTT infants as suffering from Depression.  相似文献   
80.
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