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   1332篇
  免费   170篇
  国内免费   1篇
耳鼻咽喉   7篇
儿科学   35篇
妇产科学   73篇
基础医学   187篇
口腔科学   6篇
临床医学   134篇
内科学   223篇
皮肤病学   76篇
神经病学   150篇
特种医学   23篇
外科学   118篇
综合类   53篇
预防医学   147篇
眼科学   42篇
药学   130篇
中国医学   1篇
肿瘤学   98篇
  2021年   22篇
  2020年   24篇
  2019年   19篇
  2018年   36篇
  2017年   21篇
  2016年   24篇
  2015年   33篇
  2014年   40篇
  2013年   32篇
  2012年   71篇
  2011年   88篇
  2010年   30篇
  2009年   25篇
  2008年   65篇
  2007年   74篇
  2006年   53篇
  2005年   53篇
  2004年   40篇
  2003年   48篇
  2002年   44篇
  2001年   43篇
  2000年   39篇
  1999年   38篇
  1998年   16篇
  1996年   15篇
  1995年   15篇
  1994年   13篇
  1992年   26篇
  1991年   27篇
  1990年   17篇
  1989年   23篇
  1988年   14篇
  1987年   16篇
  1986年   13篇
  1985年   15篇
  1984年   13篇
  1983年   14篇
  1981年   10篇
  1980年   14篇
  1979年   20篇
  1978年   16篇
  1977年   17篇
  1976年   13篇
  1974年   16篇
  1973年   16篇
  1972年   19篇
  1970年   16篇
  1969年   19篇
  1968年   13篇
  1967年   11篇
排序方式: 共有1503条查询结果,搜索用时 15 毫秒
61.
BACKGROUND: Accumulation of the matrix glycosaminoglycan hyaluronan occurs in many types of renal injury but could follow any provision of hyaluronan substrate to the kidney, for example, through widespread use of supplementary glucosamine in osteoarthritic conditions. Hyaluronan can increase cyclooxygenase-2 (COX-2) protein and prostaglandin production. This effect was characterized in rat renal glomeruli to determine the cellular mechanism of activation. METHODS: Isolated glomeruli were treated with purified hyaluronan (molecular mass 2 x 105 D) for up to 24 hours. RESULTS: An increase in cyclooxygenase capacity and COX-2 protein was shown to follow the activation of p38-mitogen-activated protein (MAP) kinase and to be inhibited by a specific pyridinyl imadazole inhibitor (SB 202190). Hyaluronan-induced activation of cytosolic phospholipase A2 also was shown to be a p38 MAP kinase effect in these preparations. Prostaglandin production was inhibited by COX-2-specific non-steroidal anti-inflammatory compounds (NS-398 and celecoxib) but, as shown for many non-steroidal anti-inflammatory drugs (NSAIDs), an increase in COX-2 protein accompanied this inhibition. CONCLUSIONS: We propose that these findings have clinical relevance. Prostaglandins have a number of important intrarenal regulatory effects leading to some debate over renal function with the use of NSAIDs. Where hyaluronan is increased, p38 MAP-kinase-dependent provision of prostaglandin substrate, via activation of cytosolic phospholipase A2, and a concomitant increase in cyclooxygenase-2 protein would raise renal prostaglandin levels. While NSAID treatment can prevent a rise in prostaglandin levels, it needs to be maintained to avoid possible exacerbation of pro-inflammatory conditions due to increased COX-2 protein levels.  相似文献   
62.
OBJECTIVES- To ask if slowed motor speed predicts later human immunodeficiency virus (HIV) dementia and HIV encephalitis. METHODS- In 100 deceased acquired immunodeficiency syndrome (AIDS) patients prior results from repeated testing of the movement reaction time test were correlated with later clinical signs of HIV dementia and with neuropathological signs of HIV encephalitis. Autopsy was performed in 72 patients. RESULTS- Movement reaction time 1-2 years prior to death, or at the time of clinical AIDS diagnosis predicted both development of HIV dementia (P<0.05) and HIV encephalitis at autopsy (P<0.01). CONCLUSION- Testing for early psychomotor slowing may be used to identify patients at risk of HIV dementia and HIV encephalitis.  相似文献   
63.
Studies using pharmacologic inhibitors have implicated the enzyme aldose reductase in the pathogenesis of albuminuria and diabetic renal disease. However, a clear conclusion is not easily drawn from such studies since these pharmacologic inhibitors have nonspecific properties. To examine further the role of aldose reductase, we have overexpressed the human enzyme in a transgenic rat model. Transgene expression in the kidney was predominantly localized to the outer stripe of the outer medulla, compatible with the histotopography of the straight (S3) proximal tubule. The effect of enzyme overexpression on diabetes-induced renal function and structure was then investigated. Contrary to what may have been anticipated from the previous enzyme inhibition studies, diabetes-induced albuminuria was completely prevented by the overexpression of aldose reductase. No effect of overexpression of aldose reductase on renal structure nor on urinary excretion of β2-microglobulin and N-acetyl-β-d-glucosaminidase was observed in this transgenic rat model. In conclusion, our study strongly suggests that multiple roles for aldose reductase may give it a more complex place in diabetic nephropathy than is currently recognized.  相似文献   
64.
65.
BACKGROUND: Phase III studies suggest that non-small-cell lung cancer (NSCLC) patients treated with cisplatin-docetaxel may have higher response rates and better survival compared with other platinum-based regimens. We report the final results of a randomised phase III study of docetaxel and carboplatin versus MIC or MVP in patients with advanced NSCLC. PATIENTS AND METHODS: Patients with biopsy proven stage III-IV NSCLC not suitable for curative surgery or radiotherapy were randomised to receive four cycles of either DCb (docetaxel 75 mg/m(2), carboplatin AUC 6), or MIC/MVP (mitomycin 6 mg/m(2), ifosfamide 3 g/m(2) and cisplatin 50 mg/m(2) or mitomycin 6 mg/m(2), vinblastine 6 mg/m(2) and cisplatin 50 mg/m(2), respectively), 3 weekly. The primary end point was survival, secondary end points included response rates, toxicity and quality of life. RESULTS: The median follow-up was 17.4 months. Overall response rate was 32% for both arms (partial response = 31%, complete response = 1%); 32% of MIC/MVP and 26% of DCb patients had stable disease. One-year survival was 39% and 35% for DCb and MIC/MVP, respectively. Two-year survival was 13% with both arms. Grade 3/4 neutropenia (74% versus 43%, P < 0.005), infection (18% versus 9%, P = 0.01) and mucositis (5% versus 1%, P = 0.02) were more common with DCb than MIC/MVP. The MIC/MVP arm had significant worsening in overall EORTC score and global health status whereas the DCb arm showed no significant change. CONCLUSIONS: The combination of DCb had similar efficacy to MIC/MVP but quality of life was better maintained.  相似文献   
66.
Clinical evidence of cerebral oedema occurs in approximately 1% of diabetic ketoacidosis episodes. Mortality from this serious complication is falling, but little is known of long term outcome. We describe hypopituitarism and executive dysfunction developing two years after cerebral oedema complicating diabetic ketoacidosis in a 12 year old with type 1 diabetes.  相似文献   
67.
Population carrier frequency of hMSH2 and hMLH1 mutations   总被引:6,自引:0,他引:6  
Knowledge of population carrier frequency for DNA mismatch repair (MMR) gene mutations would contribute to understanding the burden of cancer due to genetic susceptibility, but robust prevalence estimates are lacking. To estimate carrier frequency, we genotyped a cohort of relatives of mutation carriers and determined their colorectal cancer prevalence. Systematic Finnish and US data were combined with Scottish genotype and cancer prevalence data in a Bayesian calculation. The estimated carrier prevalence in the population aged 15-74 years is 1:3139 (95% Cl = 1:1247-1:7626) and these carriers are at high risk of colorectal and other cancers.  相似文献   
68.
While chronic intermittent administration of stimulants often induces behavioral sensitization in adulthood, stimulant sensitization has rarely been reported prior to weaning [around postnatal day (P) 21]. Consistent pairing of drug administration with the test context often facilitates sensitization in adults, yet young animals have been typically returned to the home cage immediately post-injection. To determine whether promoting context-dependent sensitization might facilitate expression of sensitization in preweanlings, Sprague-Dawley rats were injected daily from P14 to P20 with 0, 5, 15, or 30 mg/kg cocaine HC1 and placed for 30 min in either the experimental chamber or home cage. On P21 (test day), subjects were challenged with either 15 mg/kg cocaine or saline prior to placement in the experimental chamber. Significant sensitization of cocaine-induced stereotyped head movements was evident in animals given 15 or 30 mg/kg chronically in the experimental chamber, but not when these same doses were given in the home cage. Less consistent evidence for cocaine-induced sensitization was seen when examining locomotion, although trends for sensitization of this behavior were seen in animals chronically injected in either the test chamber or home cage. Thus, preweanlings can exhibit cocaine sensitization, particularly in terms of stereotypy, when tested shortly after the chronic exposure period, with expression of this sensitization being facilitated by pairing the chronic injections with the test context. Received: 19 November 1996/Final version: 10 December 1997  相似文献   
69.
70.
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