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   51799篇
  免费   5317篇
  国内免费   1699篇
耳鼻咽喉   492篇
儿科学   920篇
妇产科学   210篇
基础医学   3761篇
口腔科学   1053篇
临床医学   7243篇
内科学   13955篇
皮肤病学   780篇
神经病学   1860篇
特种医学   836篇
外国民族医学   1篇
外科学   4517篇
综合类   8543篇
现状与发展   11篇
一般理论   3篇
预防医学   3228篇
眼科学   405篇
药学   4586篇
  47篇
中国医学   4989篇
肿瘤学   1375篇
  2024年   196篇
  2023年   1132篇
  2022年   1695篇
  2021年   2520篇
  2020年   2399篇
  2019年   2210篇
  2018年   2015篇
  2017年   2227篇
  2016年   2412篇
  2015年   2435篇
  2014年   3715篇
  2013年   4239篇
  2012年   3199篇
  2011年   3492篇
  2010年   2699篇
  2009年   2433篇
  2008年   2231篇
  2007年   2334篇
  2006年   2070篇
  2005年   1808篇
  2004年   1413篇
  2003年   1260篇
  2002年   1099篇
  2001年   982篇
  2000年   838篇
  1999年   631篇
  1998年   540篇
  1997年   530篇
  1996年   492篇
  1995年   473篇
  1994年   421篇
  1993年   359篇
  1992年   293篇
  1991年   249篇
  1990年   208篇
  1989年   200篇
  1988年   162篇
  1987年   144篇
  1986年   138篇
  1985年   187篇
  1984年   133篇
  1983年   95篇
  1982年   109篇
  1981年   119篇
  1980年   66篇
  1979年   44篇
  1978年   45篇
  1977年   40篇
  1976年   38篇
  1975年   13篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
We have known the endogenous opioid peptide β-endorphin for 20 years. Surprisingly, our knowledge of the physiological role of this peptide and its receptors in modulation of pain perception is still fragmentary. Whereas most studies have tried to elucidate the physiological role of β-endorphin by reversing evoked responses by the opioid antagonist naloxone, this review focuses on quantification of release of β-endorphin in the brain as the approach to define physiological and pathophysiological roles of β-endorphin in relation to nociception. Using a lateral ventricle-cisterna magna perfusion model in the anesthetized rat, it was shown that depolarization of neurons in the arcuate nucleus of the hypothalamus, where β-endorphin is produced, was followed by release of β-endorphin to the cerebrospinal fluid compartment. Intense activation of spinal nociceptive pathways by intrathecal capsaicin injections also led to β-endorphin release. It is concluded that there may still be good reason to quantify β-endorphin in human cerebrospinal fluid to elucidate the role of β-endorphin in pain perception.  相似文献   
72.
本文通过对老年度性支气管炎与健康老年人甲皱微循环的对照观察,发现管袢密度、畸形管袢、输入枝管径、管袢长度、流态积分存在显著性统计学差异,提示临床应注意血管、血流因素对慢性支气管炎治疗及预后的影响。  相似文献   
73.
Abstract: This article integrates theory and research related to boundary ambiguity in parents of children with a chronic health condition. We propose that boundary ambiguity is a risk factor for psychological distress in these parents. Clinical applications and a case example highlight how boundary ambiguity can be assessed and managed in clinical settings by professionals working with parents with chronically ill children. Questions are provided for assessing boundary ambiguity in clinical and research settings, and implications for research are discussed.  相似文献   
74.
Over a 15-year period we observed seven children (four girls, three boys) who presented within the first months of life with severe renal failure and acidosis, associated with hypertension in five patients and polyuria in four. In addition, one patient had a severe cholestatic liver disease. In two families, a similarly affected sibling had died previously. Four patients were referred with the clinical diagnosis of polycystic kidney disease because of moderate enlargement of kidneys, but renal imaging (intravenous pyelography and ultrasonography) did not confirm this diagnosis. A renal biopsy, performed in all patients, showed similar features characterized by a diffuse chronic tubulo-interstitial nephritis (TIN) and particularly by the presence of microcystic dilatation of proximal tubules and Bowman's space. Liver pathology was normal in two patients, including one with hepatomegaly. However, in the patient with cholestasis there was inflammatory portal fibrosis with mild duct proliferation. Progression of the renal disease was extremely rapid and all patients reached end-stage renal failure (ESRF) before the age of 2 years (11–22 months). Two children had successful renal transplants. Although this chronic TIN shares some features with nephronophthisis, we suggest that it represents a distinct entity both on clinical and morphological grounds. The specific clinical features of this disease are its early onset and rapid progression to ESRF. Pathologically, it differs from nephronophthisis by the absence of medullary cysts and thickened tubular basement membranes and by the presence of cortical microcysts.  相似文献   
75.
Chronic rejection accounted for 32% of all graft losses in 7123 pediatric transplants. In a previous study acute, multiple acute and late acute rejections were risk factors for the development of chronic rejection. We postulated that the recent decrease in acute rejections would translate into a lower risk for chronic rejection among patients with recent transplants. We reviewed our data on patients transplanted from 1995 to 2000, and using multivariate analysis and a proportional hazards model developed risk factors for patients whose grafts had failed due to chronic rejection. A late initial rejection increased the risk of chronic rejection graft failure 3.6-fold (p < 0.001), while a second rejection resulted in further increase of 4.2-fold (p < 0.001). Recipients who received less than 5 mg/kg of cyclosporine at 30 days post-transplant had a relative risk (RR) of 1.9 (p = 0.02). Patients transplanted from 1995 to 2000 had a significantly lower risk (RR = 0.54, p < 0.001) of graft failure from chronic rejection than those who received their transplants earlier (1987-94). Since we were able to demonstrate that there is a decreased risk of chronic rejection graft failure in our study cohort, we would conclude that the goal of future transplants should be to minimize acute rejections.  相似文献   
76.
This study sought to measure the effect of pulmonary function testing (PFT) data on the decisions made by generalist physicians in the management of chronic obstructive pulmonary disease (COPD). 148 physicians were randomly assigned to two groups, both of which were asked to manage two identical fictitious but representative cases of COPD, which included history, physical, x-ray, and laboratory results. The experimental group received PFT results in addition. No significant difference was noted between the two groups in management based on availability of PFT data. The optimum utility of PFT data in the management of COPD may be exaggerated and has yet to be determined. Received from the Department of Medicine, Division of General Internal Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin. Presented at the Annual Scientific Meeting of the American College of Chest Physicians, October 28, 1992, Chicago, Illinois.  相似文献   
77.
结肠回肠反流与回肠黏膜结肠化相关性的实验研究   总被引:2,自引:0,他引:2  
目的探讨结肠回肠反流后回肠末端黏膜结肠化的机制.方法取SD大鼠60只,均为雄性,体重25¨3∞g,随机分为实验组和对照组,分别进行末端回肠-盲肠侧侧吻合术或回肠末端手术缝线,2个月后处死动物并取组织进行观察.结果实验组术后一般状况良好.大体形态学观察:实验组回肠末端黏膜表现为绒毛萎缩、间距增宽、沟变浅、光滑性增强.病理组织学:实验组表现为黏膜绒毛萎缩、间距增宽、沟变浅、上皮细胞变短、杯状细胞增多.电镜观察:实验组可见绒毛变小、变短或脱落;微绒毛变短、分布不均匀;杯状细胞数目在非坏死区增多.结论结肠-回肠反流后可导致回肠末端黏膜结肠化的变化,它可能是慢性末端回肠炎的发病基础或前期表现.  相似文献   
78.
慢性前列腺炎相关危险因素的调查报告   总被引:8,自引:1,他引:7  
目的:探索不良生活习惯、精神、心理等相关因素与慢性前列腺炎发病的关系. 方法:对600例慢性前列腺炎患者进行流行病学调查,采用单因素及多因素条件Logistic回归法进行统计分析,判断危险因素.结果:多因素Logistic回归分析发现引起慢性前列腺炎的可能因素为尿道炎、无节制的性生活、频繁的手淫、固定体位(尤其长时间骑跨、坐位)、酗酒、生活方式改变、长时间憋尿、紧张焦虑心理等.结论:本研究结果对慢性前列腺炎的预防、治疗及防止复发具有参考价值.  相似文献   
79.
The pathogenesis of late renal allograft loss is heterogeneous and difficult to diagnose. We have analyzed renal allografts in nonhuman primates to determine the relationship between alloantibodies and the graft pathology of late graft loss. Seventeen Cynomolgus monkeys were chosen from among those on several protocols for renal allotransplantation with mixed chimerism induction so that animals with and without alloantibodies were included. All animals received transient CD154 blockade and short-term cyclosporine treatment until day 28. Serial blood samples were tested for alloantibodies. Protocol biopsies and autopsy kidneys were scored for pathology and C4d deposition. Group 1, defined by complete lack of C4d deposition (24 tissue samples; 8 recipients), had no detectable alloantibodies (33 serum samples; 1-7 samples per recipient) and no evidence of chronic rejection. Three survived greater than 2 years with normal function and histology. Group 2, defined as having C4d deposition in peritubular capillaries, all made alloantibodies (100%), and most grafts later showed chronic allograft glomerulopathy (89%), and/or arteriopathy (89%). All grafts in Group 2 failed (3-27 months). Pathologic lesions of typical of chronic rejection in humans develop in monkeys, correlate with antecedent alloantibodies/C4d deposition and predict chronic rejection rather than durable accommodation.  相似文献   
80.
A patient with hepatitis C virus (HCV) infection was diagnosed with cutaneous, pulmonary and hepatic sarcoidosis following interferon alpha therapy. There are only a few cases of sarcoidosis associated with this treatment. This is the first case who not only developed sarcoidosis, but also autoimmune hypothyroidism and thrombocytopenia during interferon alpha therapy due to the immunomodulatory effects of the drug.  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