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   20175篇
  免费   1509篇
  国内免费   44篇
耳鼻咽喉   119篇
儿科学   581篇
妇产科学   531篇
基础医学   2853篇
口腔科学   408篇
临床医学   2427篇
内科学   3945篇
皮肤病学   354篇
神经病学   2215篇
特种医学   641篇
外国民族医学   1篇
外科学   1941篇
综合类   197篇
现状与发展   1篇
一般理论   21篇
预防医学   2150篇
眼科学   317篇
药学   1581篇
中国医学   58篇
肿瘤学   1387篇
  2023年   231篇
  2022年   281篇
  2021年   698篇
  2020年   473篇
  2019年   759篇
  2018年   739篇
  2017年   591篇
  2016年   589篇
  2015年   637篇
  2014年   828篇
  2013年   1110篇
  2012年   1729篇
  2011年   1661篇
  2010年   837篇
  2009年   804篇
  2008年   1281篇
  2007年   1299篇
  2006年   1097篇
  2005年   1163篇
  2004年   989篇
  2003年   880篇
  2002年   818篇
  2001年   178篇
  2000年   121篇
  1999年   142篇
  1998年   140篇
  1997年   135篇
  1996年   98篇
  1995年   78篇
  1994年   73篇
  1993年   64篇
  1992年   80篇
  1991年   70篇
  1990年   83篇
  1989年   66篇
  1988年   61篇
  1987年   77篇
  1986年   58篇
  1985年   56篇
  1984年   46篇
  1983年   40篇
  1982年   45篇
  1981年   37篇
  1979年   45篇
  1978年   33篇
  1977年   28篇
  1972年   33篇
  1968年   28篇
  1967年   26篇
  1966年   26篇
排序方式: 共有10000条查询结果,搜索用时 921 毫秒
71.
72.
After working in intensive care for thirteen years, I believed I understood some of the experiences of our patients and their families. However, my own experience on the receiving end of intensive care has demonstrated how little I knew and has changed not only my own views and perceptions, but has stimulated changes to practice in one icu.  相似文献   
73.
74.
Objective: The use of non-heart-beating donors (NHBD) has been propagated as an alternative to overcome the scarcity of pulmonary grafts. Formation of microthrombi after circulatory arrest, however, is a major concern for the development of reperfusion injury. We looked at the effect and the best route of pulmonary flush following topical cooling in NHBD. Methods: Non-heparinized pigs were sacrificed by ventricular fibrillation and divided into three groups (n = 6 per group). After 1 h of in situ warm ischaemia and 2.5 h of topical cooling, lungs in group I were retrieved unflushed (NF). In group II, lungs were explanted following an anterograde flush (AF) through the pulmonary artery with 50 ml/kg Perfadex® (6 °C). Finally, in group III, lungs were retrieved after an identical but retrograde flush (RF) via the left atrium. Flush effluent was sampled at intervals to measure haemoglobin concentration. Performance of the left lung was assessed during 60 min in our ex vivo reperfusion model. Wet-to-dry weight ratio (W/D) of both lungs was calculated as an index of pulmonary oedema. IL-1ß and TNF- protein levels in bronchial lavage fluid from both lungs were compared between groups. Results: Haemoglobin concentration (g/dl) was higher in the first effluent in RF versus AF (3.4 ± 1.1 vs 0.6 ± 0.1; p < 0.05). Pulmonary vascular resistance (dynes × s × cm−5) was 975 ± 85 RF versus 1567 ± 98 AF and 1576 ± 88 NF at 60 min of reperfusion (p < 0.001). Oxygenation (mmHg) and compliance (ml/cmH2O) were higher (491 ± 44 vs 472 ± 61 and 430 ± 33 NS, 22 ± 3 vs 19 ± 3 and 14 ± 1 NS, respectively) and plateau airway pressure (cmH2O) was lower (11 ± 1 vs 13 ± 1 and 13 ± 1 NS) after RF versus AF and NF, respectively. No differences in cytokine levels or in W/D ratios were observed between groups after reperfusion. Histology demonstrated microthrombi more often present after AF and NF compared to RF. Conclusion: Retrograde flush of the lung following topical cooling in the NHBD results in a better washout of residual blood and microthrombi and subsequent reduced pulmonary vascular resistance upon reperfusion.  相似文献   
75.
76.
77.
78.
The pathogenesis of chronic pelvic pain syndrome continues to be an enigma. The observation of inflammatory cells in urine, ejaculate, prostate fluid, and prostate tissue combined with changed local expressions of cytokines, immunoglobulins, complement, and other inflammatory markers led to the hypothesis of an involvement of the immune system in this clinical entity. This review presents a survey of the immunology-related data available for chronic pelvic pain syndrome and attempts to explain them in the context of causes and consequences.  相似文献   
79.
The eyes of a 72-year-old woman with a history of two branch retinal vein occlusions involving the left eye, were obtained postmortem and studied histopathologically. Prior to her death, she had been enrolled in the multicentered, prospective, randomized clinical trial on branch vein occlusion and treated with peripheral argon laser photocoagulation for disc neovascularization. Routine fluorescein angiograms and fundus photographs were available for clinical correlation. Despite photocoagulation, the patient had frequent recurrent episodes of vitreous hemorrhage. On histologic examination, both venous occlusions were found at arteriovenous crossings and associated with moderately sclerotic retinal arterioles. One occlusion was recanalized. Retinal inner ischemic atrophy was observed distal to the site of both venous occlusions and corresponded to areas of nonperfusion. Cystoid macular edema was not present. Three areas of neovascularization were found; one at the optic nerve head, one at the peripapillary retina, and one at the fovea. It is likely the patient's repeated vitreous hemorrhages were from one or all three areas of neovascularization demonstrated histopathologically.  相似文献   
80.
Deficits in visual-spatial ability can be associated with Parkinson's disease (PD), and there are several possible reasons for these deficits. Dysfunction in frontal-striatal and/or frontal-parietal systems, associated with dopamine deficiency, might disrupt cognitive processes either supporting (e.g., working memory) or subserving visual-spatial computations. The goal of this study was to assess visual-spatial orientation ability in individuals with PD using the Mental Rotations Test (MRT), along with other measures of cognitive function. Non-demented men with PD were significantly less accurate on this test than matched control men. In contrast, women with PD performed similarly to matched control women, but both groups of women did not perform much better than chance. Further, mental rotation accuracy in men correlated with their executive skills involving mental processing and psychomotor speed. In women with PD, however, mental rotation accuracy correlated negatively with verbal memory, indicating that higher mental rotation performance was associated with lower ability in verbal memory. These results indicate that PD is associated with visual-spatial orientation deficits in men. Women with PD and control women both performed poorly on the MRT, possibly reflecting a floor effect. Although men and women with PD appear to engage different cognitive processes in this task, the reason for the sex difference remains to be elucidated.  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