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   21610篇
  免费   1889篇
  国内免费   42篇
耳鼻咽喉   239篇
儿科学   670篇
妇产科学   395篇
基础医学   3028篇
口腔科学   322篇
临床医学   2306篇
内科学   4303篇
皮肤病学   309篇
神经病学   1966篇
特种医学   652篇
外国民族医学   3篇
外科学   2755篇
综合类   500篇
一般理论   14篇
预防医学   2255篇
眼科学   741篇
药学   1612篇
中国医学   22篇
肿瘤学   1449篇
  2022年   150篇
  2021年   332篇
  2020年   247篇
  2019年   368篇
  2018年   383篇
  2017年   289篇
  2016年   345篇
  2015年   404篇
  2014年   565篇
  2013年   829篇
  2012年   1244篇
  2011年   1326篇
  2010年   649篇
  2009年   685篇
  2008年   1102篇
  2007年   1263篇
  2006年   1198篇
  2005年   1216篇
  2004年   1182篇
  2003年   1016篇
  2002年   1012篇
  2001年   469篇
  2000年   496篇
  1999年   492篇
  1998年   305篇
  1997年   228篇
  1996年   233篇
  1995年   204篇
  1994年   175篇
  1993年   157篇
  1992年   321篇
  1991年   316篇
  1990年   300篇
  1989年   297篇
  1988年   272篇
  1987年   251篇
  1986年   283篇
  1985年   241篇
  1984年   210篇
  1983年   163篇
  1982年   164篇
  1981年   124篇
  1980年   125篇
  1979年   203篇
  1978年   145篇
  1977年   112篇
  1976年   103篇
  1975年   103篇
  1974年   117篇
  1973年   135篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
103.
104.
Elevated amniotic fluid alpha-fetoprotein and presence of acetylcholinesterase were detected in a pregnancy that resulted in an infant whose only abnormality was a hydrocele. Although these amniotic fluid findings are usually indicative of a serious fetal anomaly, our report indicates that this is not always the case.  相似文献   
105.
Effects of Stimulus Intensity on Cardiovascular Activity   总被引:2,自引:0,他引:2  
A between-groups design (N = 75) was employed to investigate the effects of stimulus intensity and repetition on cardiovascular activity. It was predicted that as intensity increased, the pattern of physiological activity would change, indicating a transition from the orienting to the defense reflex. Cardiovascular activity was represented by measures of heart rate, digital pulse amplitude, and cephalic blood content. Subjects received 12 presentations of a 1000 Hz tone of 45, 60, 75, 90, or 105 dB. Stimulus risetime was 30 msec and the duration 2 sec. Analyses of variance revealed reliable effects of intensity and repetition on all cardiovascular variables. However, neither these results nor additional multivariate analyses supported the differentiation of orienting and defense reflexes as suggested by Sokolov (1963) or Graham (1979). The importance of the startle reflex in the interpretation of these findings was discussed.  相似文献   
106.
PURPOSE: To assess internal medicine and general surgery residents' attitudes about the effects of the Accreditation Council for Graduate Medical Education duty hours regulations on medical errors, quality of patient care, and residency experiences. METHOD: In 2005, the authors surveyed 200 residents who trained both before and after duty hours reform at six residency programs (three internal medicine, three general surgery) at five academic medical centers in the United States. Residents' attitudes about the effects of the duty hours regulations on the quality of patient care, residency education, and quality of life were measured using a survey instrument containing 19 Likert scale questions on a scale of 1 to 5. Survey responses were compared using the Student's t-test. RESULTS: The response rate was 80% (159 residents). Residents reported that whereas fatigue-related errors decreased slightly, errors related to reduced continuity of care significantly increased. Additionally, duty hours regulations somewhat decreased opportunities for formal education, bedside learning, and procedures, but there was no consensus that graduates would be less well trained after duty hours reform. Residents, particularly surgical trainees, reported improvements in quality of life and reduced burnout. CONCLUSIONS: Residents in medicine and surgery had similar opinions about the effects of duty hours reform, including improved quality of life. However, resident opinions suggest that reduced fatigue-related errors have been offset by errors related to decreased continuity of care and that the quality of the educational experience may have declined. Quantifying the degree to which regulating duty hours affected errors related to discontinuity of care should be a focus of future research.  相似文献   
107.
Since its discovery, human parvovirus B19 has been linked with a broad spectrum of clinical syndromes. An aetiological role for the virus has been confirmed in erythema infectiosum, transient aplastic crisis, persistent infection manifesting as pure red cell aplasia in immunocompromised persons, non-immune hydrops fetalis and arthritis. Less commonly recognised, but receiving increasing attention recently, are the neurological manifestations, a variety of which have been described in patients with either clinically diagnosed or laboratory confirmed B19 infection. The purpose of this review is to summarise present knowledge of B19, its known and potential pathogenic mechanisms and its association with human diseases, particularly those with neurological manifestations. The outcome of the review supports an aetiological role of the virus in neurological disease. However, the pathogenesis remains unknown and elucidating this is a priority.  相似文献   
108.
A randomized trial was performed in which imaginal exposure (IE) and cognitive therapy (CT) were compared in the treatment of chronic posttraumatic stress disorder (PTSD). Patients who continued to meet PTSD caseness at the end of a 4-week symptom-monitoring baseline period (n = 72) were randomly allocated to either IE or CT. There was a significant improvement in all measures over treatment and at follow-up, although there were no significant differences between the 2 treatments at any assessment. A significantly greater number of patients who showed worsening over treatment received IE, although this effect was not found at follow-up. Patients who worsened showed a greater tendency to miss treatment sessions, rated therapy as less credible, and were rated as less motivated by the therapist. It was concluded that either exposure or a challenge to cognition can result in symptom reduction, although neither resulted in complete improvement.  相似文献   
109.
BACKGROUND. Several new antibacterial drugs have been introduced in the last 10 years with the aim of improved treatment of respiratory tract infection. AIM. The study set out to use repeat consultations as a measure of the outcome of antibiotic treatment for respiratory tract infection, and to develop a simple model for discussion of the cost effectiveness of alternative antibiotic treatments. METHOD. All consultations to one practice during a single winter were reviewed by one general practitioner. RESULTS. A total of 1140 patients had acute symptoms suggestive of respiratory infection. Of these, 899 patients (79%) were prescribed antibiotics at the first consultation and 160 of the 899 patients (18%) returned for one or more repeat consultations; only nine repeat consultations were due to adverse effects of the antibiotics prescribed. Only two patients were admitted to hospital for respiratory symptoms following initial antibiotic therapy and both patients had additional reasons for their admission. Using the highest estimates, the cost of a repeat consultation was found to be 28.54 pounds. These data were used to calculate how much more might be spent on more effective antibiotics at the first consultation. It would be difficult to justify increasing the cost of antibiotic treatment by more than 5 pounds per patient, even if the new treatment were 100% effective and all repeat consultations were due to treatment failure (5 pounds is equal to 28.54 pounds x 0.18, which is the maximum cost of a repeat consultation multiplied by the proportion of patients prescribed antibiotics who make repeat consultations). CONCLUSION. From these results and a review of the literature it can be concluded that new antibacterial drugs will have to be carefully targeted if they are to prove cost effective in practice. Other methods for reducing repeat consultation merit investigation.  相似文献   
110.
Previous investigators have reported that deletion of the protein tyrosine kinase Lyn alters mast cell (MC) signaling responses but does not affect or reduces the cytokine-mediated proliferation of mouse bone marrow-derived MC (BMMC) precursors and of mature MC. We observed that Lyn-deficient mice have more peritoneal MC than wild-type (WT) mice. Studies to explore this unexpected result showed that Lyn(-/-) BM cells expand faster than WT cells in response to interleukin (IL)-3 and stem-cell factor over the 4-5 weeks required to produce a >95% pure population of granular, receptor with high affinity for immunoglobulin E-positive BMMC. Furthermore, differentiated Lyn(-/-) BMMC continue to proliferate more rapidly than WT BMMC and undergo less apoptosis in response to cytokine withdrawal. Additionally, Lyn(-/-) BMMC support greater IL-3-mediated phosphorylation of the prosurvival kinase, Akt, and the proliferative kinase, extracellular-regulated kinase 1/2. These results identify Lyn as a negative regulator of murine MC survival and proliferation.  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