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   5300篇
  免费   507篇
  国内免费   11篇
耳鼻咽喉   52篇
儿科学   163篇
妇产科学   129篇
基础医学   666篇
口腔科学   35篇
临床医学   768篇
内科学   875篇
皮肤病学   133篇
神经病学   318篇
特种医学   538篇
外科学   682篇
综合类   131篇
一般理论   3篇
预防医学   552篇
眼科学   44篇
药学   402篇
肿瘤学   327篇
  2022年   33篇
  2021年   77篇
  2020年   57篇
  2019年   81篇
  2018年   96篇
  2017年   52篇
  2016年   81篇
  2015年   80篇
  2014年   144篇
  2013年   162篇
  2012年   239篇
  2011年   279篇
  2010年   136篇
  2009年   133篇
  2008年   251篇
  2007年   253篇
  2006年   219篇
  2005年   257篇
  2004年   194篇
  2003年   162篇
  2002年   174篇
  2001年   144篇
  2000年   169篇
  1999年   149篇
  1998年   66篇
  1997年   50篇
  1996年   68篇
  1995年   88篇
  1994年   71篇
  1993年   67篇
  1992年   131篇
  1991年   122篇
  1990年   121篇
  1989年   117篇
  1988年   112篇
  1987年   115篇
  1986年   110篇
  1985年   125篇
  1984年   95篇
  1983年   81篇
  1982年   56篇
  1981年   31篇
  1980年   39篇
  1979年   51篇
  1978年   43篇
  1977年   32篇
  1976年   43篇
  1975年   32篇
  1974年   36篇
  1971年   29篇
排序方式: 共有5818条查询结果,搜索用时 0 毫秒
81.
BACKGROUND: The UK National Health Service (NHS) R&D strategy acknowledges the importance of developing an NHS where practice and policy is more evidence-based. This paper is based on a qualitative study which aimed to identify factors which facilitate or impede evidence-based policy-making at a local level in the NHS. METHODS: The study involved a literature review and case studies of social research projects which were initiated by NHS health authority managers or general practitioner (GP) fundholders in one region of the NHS. Data were collected through in-depth interviews with lead policy-makers, GPs and researchers working on each of the case studies and analysis of project documentation. RESULTS: An over-arching theme from the analysis was that of the complexity of R&D in purchasing. The two worlds of research and health services management often sit uncomfortably together. For this reason it was not possible to describe a 'blueprint' for successful R&D, although several important issues emerged. These include sharing an appropriate model for research utilization, the importance of relationships in shaping R&D, the importance of influence and commitment in facilitating evidence-based change, and the resourcing of R&D in purchasing. CONCLUSIONS: These issues have important implications for the strategic development of R&D as well as for individual project application. Moving beyond the rhetoric of evidence-based policy-making is more likely if both policy-makers and researchers openly acknowledge this complexity and give due concern to the issues outlined.  相似文献   
82.
This article outlines specific suggestions for team members designed to help ensure that team membership is a satisfying experience. The suggestions offered provide clear guidelines for the responsibilities individual health care providers must assume when working on teams. Your proactive engagement in addressing the suggestions provided is part of an integrated, holistic approach to teams.  相似文献   
83.
New agents for treating asthma and allergic disease are now under development. From Arris Pharmaceutical comes recombinant neutral endopeptidase (rNEP), * an agent that may prove effective as prophylaxis against symptomatic episodes in patients with moderate-to-severe asthma. A group of compounds known as tryptase inhibitors may also be of use in inflammatory diseases such as asthma, as preclinical studies have shown that they can prevent airway inflammation in sheep. In addition, Tanox Biosystems is developing therapies that target immunoglobulin E (IgE), which is a key mediator of atopic allergic disease. News of recent progress with these agents was presented at an IBC USA conference on Asthma [ Philadelphia, US; October 1995 ].  相似文献   
84.
The effects of three doses of interferon alpha (IFNα, 1.5 Mu, 0.5 Mu and 0.1 Mu) on performance, mood and physiological function were examined in a double-blind placebo controlled trial. The subjects given an injection of 1.5 Mu showed symptoms which closely resembled those seen in influenza, although most of the symptoms had gone by the next day. All of the doses of IFN reduced subjective ratings of alertness, but again this effect was only apparent on the day of challenge. Subjects given the 1.5 Mu injection were slower on two of the performance tasks (a simple reaction time task and a pegboard task) both on the day of challenge and the following day. None of the other tasks in the battery was impaired by any of the doses of IFN, either on the day of challenge or the following day. These results suggest that IFNα has selective effects on performance, and it is possible that IFN-induced changes in CNS function provide a mechanism through which viral infections influence behaviour.  相似文献   
85.
We evaluated disclosure of human immunodeficiency virus (HIV) antibody status to a main sex partner and the impact on the relationship in men who have sex with men and who are enrolled in the Acquired Immunodeficiency Syndrome (AIDS) Community Demonstration Projects cohorts. Eighty-nine percent of both seronegative and seropositive men disclosed the results to their main sex partner. Seventy percent of the seronegative men and 82% of the seropositive men who did so reported that the relationship remained "as strong as ever" after 6 months. Most men who did not disclose their test results to their main partner reported being "single" after 6 months.  相似文献   
86.
Computed tomographic scan confirmation of paraprosthetic enteric fistula   总被引:1,自引:0,他引:1  
Aortoenteric anastomotic fistulae and paraprosthetic graft infections are rare but devastating complications following aortic graft surgery. Although the incidence of these complications is reported to be less than 2%, the difficulty in diagnosis and management has led to high mortality rates and extensive morbidity. The majority of patients present with either groin infection or significant gastrointestinal tract bleeding. There is, however, a subset of patients with nonspecific clinical findings in whom routine studies are not diagnostic. Computed tomography was a useful adjunct to the diagnosis of retroperitoneal infection in these patients by demonstrating small collections of periaortic gas or "black dots." The presence of periaortic gas in each instance proved to be a specific sign of a paraprosthetic-enteric fistula, as opposed to a graft infection without intestinal communication.  相似文献   
87.
Surgical resection in the management of small cell carcinoma of the lung   总被引:7,自引:0,他引:7  
In an attempt to define the role of initial surgical resection in patients with undifferentiated small cell carcinoma of the lung, we reviewed the experience of the Veterans Administration Surgical Oncology Group (VASOG). One hundred forty-eight patients with small cell carcinoma of the lung had undergone a potentially "curative" resection. This represented 4.7% of "curative" resections carried out in four major prospective adjuvant chemotherapy trials. In the early trials (101 patients), 16 patients (15.8%) died within the first 30 postoperative days. These patients have been excluded from the analysis of long-term survival, since in the more recent trials postoperative deaths were excluded prior to randomization. In the 132 patients remaining, the 5 year survival rate by the life-table method was 23.0%. The tumor of each was classified pathologically by the TNM system. Five-year survival rates for each category were as follows: T1 N0 M0 59.9%, T1 N1 M0 31.3%, T2 N0 M0 27.9%, T2 N1 M0 9.0%, and any T3 or N2 3.6%. The effect of postoperative adjuvant chemotherapy was evaluated in each of the trials. No beneficial effect of the adjuvant therapy was noted with a one or two course regimen of either nitrogen mustard or cyclophosphamide, but possible benefit, although not significant, was noted in a prolonged intermittent chemotherapy trial of cyclophosphamide either alone or alternating with methotrexate. In the most recent trial of prolonged intermittent courses of 1-(2-chlorethyl)-3-cyclohexyl-l-nitrosourea (CCNU) and hydroxyurea, a 5 year survival rate of 80.8% was noted in those receiving adjuvant chemotherapy as compared to a 38.1% in the control group. We conclude that resection is definitely indicated in patients with T1 N0 M0 lesions and probably indicated in those with T1 N1 M0 or T2 N0 M0 lesions. Primary surgical resection is contraindicated in patients with any other TNM category.  相似文献   
88.
89.
The immunochemical properties of the plastid and cytosolic isozymes of phosphoglucose isomerase (glucosephosphate isomerase; D-glucose-6-phosphate ketol-isomerase, EC 5.3.1.9) in spinach (Spinacia oleracea) and the single phosphoglucose isomerase enzyme from the cyanobacterium Synechococcus sp. were compared by an application of the enzyme-linked immunosorbent assay. Utilizing antibodies made in rabbits against subunits of purified plastid and cytosolic phosphoglucose isomerase isozymes from spinach, we demonstrate that the plastid isozyme is immunochemically more similar to the cyanobacterial enzyme than to the spinach cytosolic counterpart. The antiserum to plastid phosphoglucose isomerase crossreacted strongly with plastid phosphoglucose isomerases from other flowering plants. The antiserum to cytosolic phosphoglucose isomerase crossreacted with other plant cytosolic phosphoglucose isomerase isozymes. The results are consistent with the hypothesis [Weeden, N. F. (1981) J. Mol. Evol. 17, 133-139] that the nuclear gene specifying plastid phosphoglucose isomerase was derived from a prokaryote after the incorporation of a plastid-like symbiont into the ancestral plant cell.  相似文献   
90.
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