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   2699743篇
  免费   195458篇
  国内免费   7279篇
耳鼻咽喉   35300篇
儿科学   88625篇
妇产科学   73514篇
基础医学   387702篇
口腔科学   77064篇
临床医学   251710篇
内科学   521213篇
皮肤病学   58239篇
神经病学   215596篇
特种医学   99949篇
外国民族医学   593篇
外科学   394826篇
综合类   61632篇
现状与发展   5篇
一般理论   947篇
预防医学   214233篇
眼科学   62827篇
药学   198320篇
  12篇
中国医学   6740篇
肿瘤学   153433篇
  2021年   21096篇
  2019年   22077篇
  2018年   31664篇
  2017年   23963篇
  2016年   26280篇
  2015年   29939篇
  2014年   41570篇
  2013年   62305篇
  2012年   85923篇
  2011年   90898篇
  2010年   53610篇
  2009年   49760篇
  2008年   83830篇
  2007年   88964篇
  2006年   89589篇
  2005年   85922篇
  2004年   82422篇
  2003年   78381篇
  2002年   75929篇
  2001年   131221篇
  2000年   134609篇
  1999年   112146篇
  1998年   30670篇
  1997年   27079篇
  1996年   27012篇
  1995年   25828篇
  1994年   23933篇
  1993年   22226篇
  1992年   86800篇
  1991年   84232篇
  1990年   81163篇
  1989年   77712篇
  1988年   71318篇
  1987年   69693篇
  1986年   66072篇
  1985年   62865篇
  1984年   46716篇
  1983年   39790篇
  1982年   23034篇
  1979年   41818篇
  1978年   29329篇
  1977年   24536篇
  1976年   23322篇
  1975年   24298篇
  1974年   29585篇
  1973年   28699篇
  1972年   26617篇
  1971年   24693篇
  1970年   22963篇
  1969年   21265篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
The precise molecular cause of insulin resistance has not yet been elucidated. Resistance to the normal action of insulin contributes to the pathogenesis of a number of common human disorders, including type 1 (insulin-dependent) and type 2 (non-insulin-dependent) diabetes mellitus, hypertension, and the Metabolic Syndrome X, thus constituting a major public health problem. A disease program aimed at combating this disorder should focus on the identification of targets for therapeutic intervention which may overcome insulin resistance and hence the associated metabolic consequences characteristic of the Metabolic Syndrome. Although the primary defect in the pathogenesis of type 2 diabetes is unknown, genetic and environmental factors are likely to contribute to the manifestation of this progressive metabolic disorder, which is usually not clinically apparent until mid-life. Defects at the level of glucose uptake/phosphorylation characterize insulin resistance in skeletal muscle of type 2 diabetic patients. Identification of putative components of the insulin receptor-signaling pathway may offer insights into mechanisms involved in insulin resistance. Enhanced flux of free fatty acids due to impaired lipid metabolism may contribute to impaired insulin secretion and peripheral insulin resistance. Genes regulating lipolysis are prime candidates for susceptibility towards the metabolic syndrome. Here we describe pathways constituting complex interactions that control glucose homeostasis. We will be considering (1) regulation of glucose uptake by the insulin receptor signaling pathway, and (2) control of adipogenesis and insulin sensitivity by the sterol response element binding protein (SREBP) pathway.  相似文献   
52.
53.
54.
Infections due to Penicillium species other than P.marneffei are rare. We identified a boy with X-linked chronic granulomatous disease (X-CGD) with a pulmonary nodule and adjacent rib osteomyelitis caused by Penicillium piceum. The only sign of infection was an elevated sedimentation rate. P. piceum was isolated by fine needle aspirate and from excised infected tissues. Surgical removal and one year of voriconazole treatment were very well tolerated and led to complete recovery. Microbiological, microscopic and molecular studies support the fungal diagnosis. P. piceum should be considered as a relevant pathogen in immunocompromised patients.  相似文献   
55.
ABSTRACT: Background: Although increases in perinatal mortality risk associated with fetal macrosomia are well documented, the optimal route of delivery for fetuses with suspected macrosomia remains controversial. The objective of this investigation was to assess the risk of neonatal death among macrosomic infants delivered vaginally compared with those delivered by cesarean section. Methods: Data were derived from the U.S. 1995–1999 Linked Live Birth‐Infant Death Cohort files and term (37–44 wk), single live births to United States resident mothers selected. A proportional hazards model was used to analyze the risk of neonatal death associated with cesarean delivery among 3 categories of macrosomic infants (infants weighing 4,000–4,499 g; 4,500–4,999 g; and 5,000+ g). Results: After controlling for maternal characteristics and complications, the adjusted hazard ratio for neonatal death associated with cesarean delivery among the 3 categories of macrosomic infants was 1.40, 1.30, and 0.85. Conclusions: Although cesarean delivery may reduce the risk of death for the heaviest infants (5,000+ g), the relative benefit of this intervention for macrosomic infants weighing 4,000–4,999 g remains debatable. Thus, policies in support of prophylactic cesarean delivery for suspected fetal macrosomia may need to be reevaluated. (BIRTH 33:4 December 2006)  相似文献   
56.
57.
58.
59.
OBJECTIVE: To explore the impact of timing and type of ultrasound, particularly three-dimensional (3D), exposure on maternal-fetal attachment and maternal health behavior during pregnancy. METHODS: Subjects were 68 women aged 18 years or older expecting their first child who presented for a routine ultrasound scan at around either 12 or 18 weeks' gestation in Nepean Hospital, Western Sydney. Women completed questionnaires assessing maternal-fetal attachment and health behavior, and were then allocated arbitrarily to either two-dimensional (2D) or 3D ultrasound examination. Repeat questionnaires were completed 1 week later. RESULTS: Maternal-fetal attachment increased after both 2D and 3D ultrasound exposure, and the effect was moderated by the timing of exposure, with women receiving their first ultrasound examination at around 12 weeks showing the greatest change. Alcohol consumption was the only behavior to show significant change following ultrasound exposure, with a reduction in the reported average number of drinks per week. There was no significant difference in the pattern of change for 2D compared with 3D ultrasound exposure, and no effect of ultrasound exposure on maternal perception of the fetus. CONCLUSIONS: Ultrasound has a positive impact on maternal-fetal attachment, particularly in the first trimester. 3D ultrasound did not offer enhanced benefits. Associations between ultrasound exposure and alcohol consumption warrant further investigation. Larger samples are needed to clarify the moderating effects of gestational age and type of ultrasound exposure.  相似文献   
60.
Although surgical lung resection could improve prognosis in some patients with multidrug-resistant tuberculosis (MDR-TB), there are no reports on the optimal candidates for this surgery. The aim of the present study was to elucidate the prognostic factors for surgery in patients with MDR-TB. Patients who underwent lung resection for the treatment of MDR-TB between March 1993 and December 2004 were included in the present study. Treatment failure was defined as greater than or equal to two of the five cultures recorded in the final 12 months of treatment being positive, any one of the final three cultures being positive, or the patient having died during treatment. The variables that affected treatment outcomes were identified through univariate and multivariate logistic regression analysis. In total, 79 patients with MDR-TB were included in the present study. The treatment outcomes of 22 (27.8%) patients were classified as failure. A body mass index <18.5 kg x m(-2), primary resistance, resistance to ofloxacin and the presence of a cavitary lesion beyond the range of the surgical resection were associated with treatment failure. Low body mass index, primary resistance, resistance to ofloxacin and cavitary lesions beyond the range of resection are possible poor prognostic factors for surgical lung resection in multidrug-resistant tuberculosis patients.  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