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   17636篇
  免费   1866篇
  国内免费   178篇
耳鼻咽喉   361篇
儿科学   529篇
妇产科学   911篇
基础医学   920篇
口腔科学   379篇
临床医学   1846篇
内科学   3078篇
皮肤病学   158篇
神经病学   1276篇
特种医学   195篇
外科学   4527篇
综合类   776篇
现状与发展   1篇
一般理论   4篇
预防医学   2274篇
眼科学   153篇
药学   941篇
  11篇
中国医学   131篇
肿瘤学   1209篇
  2024年   55篇
  2023年   721篇
  2022年   842篇
  2021年   1422篇
  2020年   1236篇
  2019年   1341篇
  2018年   1350篇
  2017年   1117篇
  2016年   907篇
  2015年   812篇
  2014年   1377篇
  2013年   1516篇
  2012年   744篇
  2011年   880篇
  2010年   583篇
  2009年   688篇
  2008年   635篇
  2007年   575篇
  2006年   456篇
  2005年   357篇
  2004年   289篇
  2003年   240篇
  2002年   184篇
  2001年   178篇
  2000年   147篇
  1999年   141篇
  1998年   123篇
  1997年   102篇
  1996年   87篇
  1995年   87篇
  1994年   71篇
  1993年   55篇
  1992年   43篇
  1991年   52篇
  1990年   47篇
  1989年   42篇
  1988年   28篇
  1987年   24篇
  1986年   18篇
  1985年   17篇
  1984年   14篇
  1983年   11篇
  1982年   15篇
  1981年   5篇
  1980年   12篇
  1979年   5篇
  1978年   4篇
  1977年   7篇
  1976年   4篇
  1973年   5篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Aims The Abciximab Before Direct Angioplasty and Stenting inMyocardial Infarction Regarding Acute and Long-term Follow-up(ADMIRAL) study demonstrated that early inhibition of the plateletglycoprotein IIb/IIIa (GP IIb/IIIa) receptor with abciximabled to improved coronary patency, left ventricular function,and clinical outcomes. The current long-term follow-up studyevaluated the durability of the positive outcomes. Methods and results The randomized double-blind ADMIRAL trialenrolled 300 patients who received either abciximab plus stentingor placebo plus stenting for the treatment of ST-elevation myocardialinfarction (STEMI). Abciximab (bolus of 0.25 mg/kg bodyweight, followed by 12 h infusion of 0.125 µg/kgper min) was administered to 149 patients, whereas 151 patientsreceived placebo. Long-term follow-up was conducted in a blindedmanner by either patient chart review or telephone interview.Long-term follow-up data were obtained on 288 patients (96%).After 3 years, using an intent-to-treat analysis, the outcomeof all-cause mortality occurred in 9.1% of abciximab-treatedpatients when compared with 12.2% of placebo patients, absoluteand relative risk reductions of 3.1 and 25%, respectively (P=0.36).Parallel Kaplan–Meier curves were observed for the cumulativeincidence of death or re-infarction, which was reduced from16.9% in the placebo group to 11.8% in the abciximab group,absolute and relative risk reductions of 5.1 and 30%, respectively(P=0.20). Rates of recurrent ischaemia were significantly reducedfrom 21.7 to 11.5% (P=0.05). Conclusion Adjunctive abciximab to primary stenting for STEMIelicits favourable clinical outcomes with the same absoluterisk reductions of hard clinical outcomes from 30 days up to3 years of follow-up.  相似文献   
62.
Low-frequency stimulation is associated with long-term depression (LTD) of synaptic efficacy in various brain structures. Like long-term potentiation (LTP), homosynaptic LTD in area CA1 of the hippocampus appears to require NMDA receptor activation, changes in postsynaptic calcium concentration and phospholipase A2 (PLA2) activation. Arachidonic acid (AA) is released after the activation of calcium-dependent phospholipases and free AA is rapidly metabolized to a family of bioactive products (the eicosanoids) which are thought to be both intracellular and extracellular messengers. In the present study, we investigated the involvement of the cyclooxygenase and lipoxygenase pathways of AA metabolism in the formation of homosynaptic LTD in the rat hippocampus. Stimulation at 1 Hz for 15 min was used to produce homosynaptic depression in area CA1 of hippocampal slices. LTD induction was partially blocked by bromophenacyl bromide (50–100 μM), a selective PLA2 inhibitor, and by the a nonselective lipoxygenase inhibitor nordihydroguaiaretic acid (NDGA; 100 μM). In contrast, the specific cyclooxygenase blocker indomethacin (100 μM) did not significantly reduce hippocampal LTD. Since NDGA interferes with LTD formation, we examined whether specific inhibitors of 5- and 12-lipoxygenases were capable of blocking LTD expression. The 12-lipoxygenase inhibitor baicalein at a concentration of 50 μM reduced LTP formation when given in the bath, an effect that was less pronounced with the 5-lipoxygenase inhibitor AA-861. These data suggest that the activation of endogenous PLA2 and the formation of 12-lipoxygenase metabolites of AA may be important factors controlling the expression of hippocampal LTD.  相似文献   
63.
Bath application of -fucose and -fucosyllactose ( F1 increases the potentiation of the population spike amplitude (POP-spike) and the field excitatory postsynaptic potential (fEPSP) after tetanization of the Schaffer collaterals of the rat hippocampus. The ineffective isomers -fucose and 3-fucosyllactose (3-F1) have no such effect. Since not only the maintenance of long-term potentiation LTP is influenced but also its induction is drastically improved, an effect of the sugars via the formation of glycoproteins but also via different actions on induction mechanisms is discussed.  相似文献   
64.
We studied 18 patients who had undergone surgery for herniated lumbar discs between the ages of 11 and 17 years. The inclusion criteria for girls was an age of 15 years or below and for boys 17 or below at surgery. The mean follow-up time was 10 years and the clinical outcome was good. Age at surgery and length of the follow-up had no effect on the result. The radiological disc height at follow-up did not correlate with the follow-up time or age of the patient at operation. MRI scans at follow-up from ten patients operated at less than 15 years of age revealed multilevel disc degeneration but favourable clinical results.  相似文献   
65.
Outcomes assessment holds great promise to improve the quality and efficiency of health care. By subjecting practices to rigorous and systematic analysis, we should be in a position to make judgments about what does and does not work in clinical practice. However, the outcomes of outcomes assessment themselves should be approached with the same critical eye. Among the many sorts of criteria by which to evaluate outcomes assessment are several key parameters: foremost among them are cognitive outcomes, ethical outcomes, and economic outcomes. Only when these outcomes are thoroughly explored and taken into account will the fullest potential of outcomes assessment be realized.  相似文献   
66.
A literature search was conducted to identify 'nursing led in-patient units' where the nurse is the designated leader of the clinical team. The review concentrates on studies which have attempted to measure the impact of nursing-led in-patient units and reviews both the methodology and outcomes. Three major bodies of work were identified. Lydia Hall's evaluation of the Loeb Center for Nursing and Rehabilitation (USA) is reviewed in some detail. This work was the model for 'nursing beds' at the two Oxfordshire Nursing Development Units (UK) in the 1980s. Studies evaluating these centres are reviewed and reports of similar UK units discussed. A third body of work evaluates a nurse-managed critical care environment. Common features include a case mix based on nursing need with nurses having authority to admit and discharge patients. While results are generally favourable, with improved patient independence, fewer readmissions, lower mortality and cost savings reported in some or all of the studies, all studies reviewed demonstrate the difficulties of applying an experimental model to real life clinical services. Methodological limitations render firm conclusions difficult. Techniques adopted from studies in field settings, the so-called 'quasi-experiment', are advocated as a remedy, as is further study of the process of care in investigating this model of care delivery.  相似文献   
67.
Expression of the immediate early gene zif/268 (also termed NGFI-A, Krox 24, TIS8 and Egr-1) was investigated in awake rats following various long-term potentiation (LTP) induction protocols.zif/268 mRNA (Northern blots) and protein (immunohistochemistry) levels sharply increased following LTP, and followed a time course characteristic of other immediate early genes. When measured across 3 tetanization protocols known to produce differing degrees of LTP persistence,zif/268 induction was found to be more highly correlated with LTP duration than with the magnitude of initial LTP. These data support the hypothesis that the immediate early gene zif/268 plays a role as a third messenger in the cascade of cellular and nuclear events that govern the persistence of LTP.  相似文献   
68.
69.
The disparities in health care and health outcomes between the majority population and cultural and racial minorities in the United States are a problem that likely is influenced by the lack of culturally competent care. Emergency medicine and other primary-care specialties remain on the front lines of this struggle because of the nature of their open-door practice. To provide culturally appropriate care, health care providers must recognize the factors impeding cultural awareness, seek to understand the biases and traditions in medical education potentially fueling this phenomenon, and create a health care community that is open to individuals' otherness, thus leading to better communication of ideas and information between patients and their health care providers. This article highlights the rationale for and current problems in teaching cultural competency and examines several different models implemented to teach and promote cultural competency along the continuum of emergency medicine learners. However, the literature addressing the true efficacy of such programs in leading to long-lasting change and improvement in minority patients' clinical outcomes remains insufficient.  相似文献   
70.
Laparoscopic colposuspension is one of many new operations for treating female urinary stress incontinence. With initially reported success rates similar to those of the traditional open procedure, it appears to combine the advantages of laparoscopy (such as minimal invasiveness and quicker return to normal activities) with the effectiveness of the standard procedure. Different methods and approaches are used, but endoscopic suture techniques remain difficult and time-consuming. The use of endostapling devices for fixation of alloplastic material has been a tempting alternative. We present a case during which laparoscopic colposuspension was performed using staples and mesh. Incontinence did not improve, and the patient suffered severe chronic pain for 18 months postoperatively. Removal of the alloplastic material and traditional abdominal resuspension led to complete cure.  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