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   9340篇
  免费   746篇
  国内免费   78篇
耳鼻咽喉   204篇
儿科学   296篇
妇产科学   211篇
基础医学   1157篇
口腔科学   209篇
临床医学   823篇
内科学   1604篇
皮肤病学   198篇
神经病学   1040篇
特种医学   501篇
外科学   1283篇
综合类   210篇
一般理论   7篇
预防医学   912篇
眼科学   471篇
药学   538篇
中国医学   2篇
肿瘤学   498篇
  2021年   149篇
  2019年   104篇
  2018年   117篇
  2017年   84篇
  2016年   105篇
  2015年   125篇
  2014年   206篇
  2013年   284篇
  2012年   400篇
  2011年   405篇
  2010年   252篇
  2009年   252篇
  2008年   385篇
  2007年   402篇
  2006年   384篇
  2005年   409篇
  2004年   419篇
  2003年   366篇
  2002年   334篇
  2001年   321篇
  2000年   302篇
  1999年   317篇
  1998年   104篇
  1997年   109篇
  1996年   90篇
  1995年   99篇
  1994年   94篇
  1993年   86篇
  1992年   193篇
  1991年   198篇
  1990年   203篇
  1989年   166篇
  1988年   163篇
  1987年   189篇
  1986年   167篇
  1985年   201篇
  1984年   124篇
  1983年   104篇
  1982年   84篇
  1981年   81篇
  1980年   78篇
  1979年   113篇
  1978年   111篇
  1977年   85篇
  1976年   84篇
  1975年   80篇
  1974年   97篇
  1973年   96篇
  1972年   82篇
  1970年   86篇
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
61.
62.
The Model for End-Stage Liver Disease (MELD) is used to assign priority for liver transplantation candidates. The Organ Procurement and Transplantation Network (OPTN) approved recognized exceptional diagnoses (RED's) for which MELD fails to accurately measure priority. Centers can request increased MELD points in cases not recognized by this policy (non-RED's). Our aim was to compare regional practices to justify non-RED requests for MELD adjustments. The UNOS/OPTN database was queried to extract all adult cases for which a non-RED MELD adjustment was requested from 2/27/02 until 8/27/03. The data were stratified by region and justification. Data for 29,510 listings were available. 26,947 had complete diagnosis information. There were 827 non-RED requests of which 477 (57.7%) petitions were approved by the regional review boards (RRBs). The approval rate varied significantly among regions (range: 28-75%, p<0.0001). The most common non-RED's were complications of portal hypertension (48%). The percentage of patients listed with non-RED's varied significantly among regions (0.7-8.3 %, p<0.0001), as did the proportion of patients transplanted with non-RED's (2.1-31.9%, p<0.0001). Demographics did not differ among regions requesting non-REDs.Widespread regional variations exist in the handling of requests for non-REDs. These variations point to the need for reform to standard exception criteria.  相似文献   
63.
Obsessive-compulsive disorder (OCD) is a distressing and functionally impairing disorder that can emerge as early as age 4. Cognitive behavior therapy (CBT) for OCD in youth shows great promise for amelioration of symptoms and associated functional impairment. However, the empirical evidence base for the efficacy of CBT in youth has some significant limitations, particularly as related to treating the very young child with OCD. This report includes a quantitative review of existing child CBT studies to evaluate evidence for the efficacy of CBT for OCD. It identifies gaps in the literature that, when addressed, would enhance the understanding of effective treatment in pediatric OCD. Finally, it presents a proposed research agenda for addressing the unique concerns of the young child with OCD.  相似文献   
64.

Objectives:  

To examine the extent to which school climate and school pressure could predict other aspects of adolescents’ lives, most particularly their emotional health and bullying. Furthermore, the study sought to investigate if these relationships were consistent across countries.  相似文献   
65.
Pharmacokinetics of cyclosporine in the weanling pig   总被引:1,自引:0,他引:1  
  相似文献   
66.
OBJECTIVES. The purposes of the study were to assess the potential impact of the North American Free Trade Agreement (NAFTA) on medical care in Mexico and to identify internal measures Mexico could take to increase the benefits and minimize the risks of free trade. METHODS. The dual nature of the health sector is examined; the Mexican, Canadian, and US health care systems are compared; and modes and consequences of international exchange of health services are analyzed. RESULTS. Four issues require immediate attention: accreditation of health care facilities, licensing and certification of professionals, technology assessment, and financial equity. CONCLUSIONS. NAFTA offers opportunities for positive developments in Mexico, provided risks can be anticipated and preventive measures can be taken to avoid negative impacts on the health system. Medical services, like other elements of the Mexican economy, must be modernized to respond to the demands of global competition. The Mexican National Academy of Medicine has recommended to the Mexican government (1) internal strengthening of the Mexican health care system to improve its ability to respond to the new conditions created by NAFTA and (2) a gradual process to facilitate equitable and mutually beneficial interactions among the three countries.  相似文献   
67.
OBJECTIVE: This study was carried out to compare the efficacy of lithium carbonate with that of valproate in acute mania and to determine whether pretreatment clinical characteristics, such as the presence of a mixed affective state, might predict a differential response to the two drugs. METHOD: Twenty-seven patients meeting DSM-III-R criteria for acute manic episodes underwent a 3-week, randomized, double-blind, parallel-groups trial of treatment with lithium carbonate or valproate. Symptom severity was measured by using the Schedule for Affective Disorders and Schizophrenia, change version (SADS-C), the Global Assessment Scale (GAS), and the Brief Psychiatric Rating Scale (BPRS). Drug effects were compared by using repeated measures analysis of variance (ANOVA). RESULTS: At the end of the study, nine of 14 patients treated with valproate and 12 of 13 patients treated with lithium had responded favorably, as measured by changes in the SADS-C mania, BPRS, and GAS scores. Elevated pretreatment SADS-C depression scores were associated with good response to valproate. ANOVA revealed a significant interaction between drug and mixed affective state with respect to treatment response. CONCLUSIONS: Lithium and valproate were both effective in improving manic symptoms, and lithium was slightly more efficacious overall. Unlike the case with lithium, favorable response to valproate was associated with high pretreatment depression scores. Therefore, treatment with valproate alone may be particularly effective in manic patients with mixed affective states.  相似文献   
68.
R J Blendon  L H Aiken  H E Freeman  C R Corey 《JAMA》1989,261(2):278-281
A 1986 national survey of use of health services shows a significant deficit in access to health care among black compared with white Americans. This gap was experienced by all income levels of black Americans. In addition, the study points to significant underuse by blacks of needed medical care. Moreover, blacks compared with whites are less likely to be satisfied with the qualitative ways their physicians treat them when they are ill, more dissatisfied with the care they receive when hospitalized, and more likely to believe that the duration of their hospitalizations is too short.  相似文献   
69.
The two major applications of whole post-implantation rat embryo culture (WEC) are as a test for teratogenicity in safety evaluation studies and as a tool in the investigation of mechanisms of teratogenesis. As a test system, WEC possesses many of the characteristics necessary for an in vitro screen. However, its use on a large scale is disqualified for reasons of cost and the demand for technical expertise to perform cultures and interpret findings, compared with other in vitro teratogenicity screens, although its use might be preferred when only a few compounds require testing. The major value of WEC lies in its use for studying mechanisms of teratogenesis. The opportunity to study the embryo in isolation and the versatility afforded by the technique offer considerable advantages in this context.  相似文献   
70.
OBJECTIVE: The American Psychiatric Association's DSM-IV Work Group on Late Luteal Phase Dysphoric Disorder (LLPDD) reanalyzed existing data from prospective, daily symptom ratings to evaluate the DSM-III-R criteria for LLPDD. The objectives were to 1) evaluate the individual symptoms presently required for the diagnosis and other symptoms, 2) determine the proportion of treatment-seeking women who meet the LLPDD criteria, and 3) explore the association between LLPDD and other mental disorders. METHOD: Data from over 1,000 women seeking evaluation for premenstrual complaints at five U.S. sites were examined. The data from 670 of these women were sufficiently complete to warrant evaluation by four different methods of assessing symptom change. RESULTS: Depending on the assessment method used, 14% to 45% of the women met the criteria for LLPDD. The current DSM-III-R symptoms were classified as positive for 7% to 54% of the women. Each of these symptoms was significantly more common among women with LLPDD regardless of the assessment method used. Five symptoms not presently included were also significantly more common. Women who had had mental disorders in the past, but not present, showed a significantly greater, but very small, relative risk of LLPDD. CONCLUSIONS: The variability in the frequency of LLPDD diagnosis according to method of assessing symptom change underscores the need for a uniform assessment method. The five additional symptoms with frequencies comparable to those of the DSM-III-R symptoms should be studied further for possible inclusion in the criteria.  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