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   80907篇
  免费   3649篇
  国内免费   334篇
耳鼻咽喉   1043篇
儿科学   2179篇
妇产科学   2013篇
基础医学   10615篇
口腔科学   2979篇
临床医学   5851篇
内科学   19873篇
皮肤病学   1658篇
神经病学   6868篇
特种医学   2447篇
外国民族医学   6篇
外科学   9685篇
综合类   430篇
一般理论   28篇
预防医学   8481篇
眼科学   1310篇
药学   5362篇
中国医学   311篇
肿瘤学   3751篇
  2023年   545篇
  2022年   1015篇
  2021年   2213篇
  2020年   1181篇
  2019年   1898篇
  2018年   3946篇
  2017年   2408篇
  2016年   1809篇
  2015年   1912篇
  2014年   2624篇
  2013年   3496篇
  2012年   5350篇
  2011年   5713篇
  2010年   3104篇
  2009年   2584篇
  2008年   4588篇
  2007年   4758篇
  2006年   4395篇
  2005年   4405篇
  2004年   3994篇
  2003年   3741篇
  2002年   3487篇
  2001年   1856篇
  2000年   1976篇
  1999年   1601篇
  1998年   585篇
  1997年   390篇
  1996年   377篇
  1995年   325篇
  1994年   276篇
  1993年   278篇
  1992年   809篇
  1991年   644篇
  1990年   619篇
  1989年   538篇
  1988年   476篇
  1987年   496篇
  1986年   435篇
  1985年   379篇
  1984年   279篇
  1983年   238篇
  1979年   210篇
  1978年   174篇
  1977年   152篇
  1975年   176篇
  1974年   185篇
  1973年   169篇
  1972年   171篇
  1971年   166篇
  1968年   155篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
992.
993.
Although thyroid cancer represents less than 1% of malignant tumours, its increased incidence detected in recent years and the appearance and development of new drugs targeting specific molecular targets has attracted the attention of the doctors involved in this pathology, especially medical oncologists. For this reason it is important at this critical point, when treatment may be substantially changed, to establish and agree updated guidelines. These guidelines should incorporate the newly developed strategies that, although still preliminary in evidence level, will surely have an important role, especially in relapsed and refractory tumours, which are unsuitable for surgical or radio-iodine treatment. Particular histological and molecular features of these tumours must be taken into account in order to optimise therapeutic approaches.  相似文献   
994.
ObjectiveOne hundred thirty-one cases of postsurgical infections were reported in Southern Region of Brazil between August 2007 and January 2008. Thirty-nine (29.8%) cases were studied; this report describes epidemiological findings, species identification, antimicrobial susceptibility and clonal diversity of rapidly growing mycobacteria isolated in this outbreak.MethodsAll 39 isolates were analyzed by Ziehl-Nielsen stained smear, bacterial culture and submitted to rpoB partial gene sequencing for identification. The isolates were also evaluated for their susceptibility to amikacin, cefoxitin, clarithromycin, ciprofloxacin, doxycycline, tobramycin and sulfamethoxazole.ResultsThirty-six isolates out of the confirmed cases were identified as Mycobacterium massiliense and the remaining three were identified as Mycobacterium abscessus, Mycobacterium chelonae and Mycobacterium fortuitum. All M. massiliense isolates were susceptible to amikacin (MIC90 = 8 μg/mL) and clarithromycin (MIC90 = 0.25 μg/mL) but resistant to cefoxitin, ciprofloxacin, doxycycline, tobramycin and sulfamethoxazole. Molecular analysis by pulsed-field gel electrophoresis clustered all 36 M. massiliense isolates and showed the same pattern (BRA 100) observed in three other outbreaks previously reported in Brazil.ConclusionsThese findings suggest a common source of infection for all patients and reinforce the hypotheses of spread of M. massiliense BRA100 in Brazilian hospital surgical environment in recent years.  相似文献   
995.
The recent medical literature has been using the term vulnerability to refer to harm to human integrity. The concept is multifaceted. Bioethics researchers conceive vulnerability as one of the basic anthropological features of the human condition. On the other hand, some bioethics scholars advocate using the terms susceptibility or variable vulnerability to refer to diseased or destitute populations. Also, frailty and variable vulnerability are correlated but not equivalent conditions which have been described somehow interchangeably in the recent medical literature, especially in the study of the ageing phenomena. The extremes of age are especially vulnerable periods of life and there has been growing evidence that neonatal and early life events have long-term influence on both the ageing process and frailty. This paper discusses some issues relevant to vulnerability and frailty and how one could possibly distinguish between them. There is still much to be learned about how frailty and variable vulnerability affect the ageing process across the life span.  相似文献   
996.
Abstract: Pancreatic cancer is a major health problem because of the aggressiveness of the disease and the lack of effective systemic therapies. Melatonin (MEL) has antioxidant activity and prevents experimental genotoxicity. The specific inhibitor of cyclooxygenase‐2 (COX‐2), celecoxib (CEL), increases the efficacy of chemoradiotherapy in advanced pancreatic cancer. The objective of the study was the comparison and synergic effect of MEL and CEL during either the induction or progression phases of the tumor process, measuring parameters of oxidative stress, number of tumor nodules and survival of animals with pancreatic cancer. Pancreatic cancer was induced by N‐nitrosobis (2‐oxopropyl)amine) (BOP) in Syrian hamsters. Melatonin and/or CEL were administered during the induction, postinduction as well as during both phases. The presence of tumor nodules were observed macroscopically in pancreatic and splenic areas, and the levels of lipoperoxides (LPO), reduced glutathione (GSH), superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH‐Px) in pancreatic tissue were measured. The increases in tumor nodules and LPO as well as the reductions in GSH and enzymatic antioxidants in the pancreas induced by BOP were related to a lower survival rate of animals. The administration of MEL exerted a more potent beneficial effect than CEL treatment on the reduction in tumor nodules, oxidative stress and death of experimental BOP‐treated animals. The combined treatment only exerted a synergistic beneficial effect when administered during the induction phase. Melatonin by itself had significant beneficial actions in improving the survival of hamsters.  相似文献   
997.
998.
999.
Improving the outcome of acute pancreatitis through prognostic markers has been a matter of ample research. We evaluate the clinical usefulness of four serum markers in comparison to Ranson’s score. Serum measurements of C-reactive protein (CRP), interleukin-6, -10 (IL-6, IL-10), and pancreatitis-associated protein (PAP) were performed. The usefulness of each marker for predicting severity was compared with that of Ranson’s score. Time of evolution was considered for improving their usefulness. Seventy-one patients were studied. Severe cases had higher levels of all markers, although only IL-10 had better accuracy than Ranson’s. In patients admitted during the first 48 h, IL-6, IL-10, and PAP had improved accuracy over Ranson’s; however, after this time frame, only CRP outperformed Ranson’s score. Analysis of time frames improved the accuracy of all markers. Therefore, time of evolution should be considered when using these parameters for a better prognosis.  相似文献   
1000.
The hypertriglyceridemic waist phenotype, the National Cholesterol Education Program-Adult Treatment Panel III (NCEP-ATP III) criteria, and the International Diabetes Federation (IDF) criteria have been proposed as screening tools to identify subjects with features of the metabolic syndrome and therefore at increased cardiometabolic risk. The aim of the present study was to compare the ability of these 3 clinical approaches to identify individuals at increased cardiometabolic risk as suggested by the presence of deteriorated markers such as hyperinsulinemia, elevated apolipoprotein B levels, small low-density lipoprotein particles, high C-reactive protein concentrations, and low adiponectin levels. For that purpose, physical and cardiometabolic characteristics of a sample of 272 white men recruited for various metabolic investigations were studied. The hypertriglyceridemic waist phenotype was defined as having both a high waist circumference (≥90 cm) and increased fasting triglyceride levels (≥2.0 mmol/L). Having at least 3 of the 5 NCEP-ATP III criteria or waist circumference of at least 94 cm plus any 2 of the 4 additional IDF criteria was also used to identify individuals at increased cardiometabolic risk. A large proportion of men with the hypertriglyceridemic waist phenotype also met the NCEP-ATP III (82.7%) or IDF (89.2%) criteria. Men with the hypertriglyceridemic waist phenotype were characterized by alterations in their lipoprotein-lipid profile that included small low-density lipoprotein particles, increased apolipoprotein B and insulin levels, as well as reduced adiponectin concentrations, which were similar to individuals meeting the NCEP-ATP III or the IDF criteria. Moreover, the Framingham risk score of men meeting any of the 3 screening tools criteria was higher and was similar across the 3 approaches (4.2, 3.8, and 3.7, respectively). These results suggest that hypertriglyceridemic waist may be as discriminant as the NCEP-ATP III or the IDF criteria and could be used as an initial screening approach to identify individuals with deteriorated cardiometabolic risk markers.  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