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   775篇
  免费   43篇
  国内免费   41篇
耳鼻咽喉   4篇
儿科学   51篇
妇产科学   8篇
基础医学   62篇
口腔科学   21篇
临床医学   94篇
内科学   187篇
皮肤病学   5篇
神经病学   19篇
特种医学   162篇
外科学   116篇
综合类   13篇
预防医学   22篇
眼科学   9篇
药学   50篇
中国医学   1篇
肿瘤学   35篇
  2024年   2篇
  2022年   2篇
  2021年   7篇
  2020年   4篇
  2019年   7篇
  2018年   12篇
  2017年   8篇
  2016年   3篇
  2015年   7篇
  2014年   14篇
  2013年   20篇
  2012年   19篇
  2011年   22篇
  2010年   41篇
  2009年   44篇
  2008年   21篇
  2007年   35篇
  2006年   21篇
  2005年   22篇
  2004年   10篇
  2003年   10篇
  2002年   18篇
  2001年   20篇
  2000年   15篇
  1999年   19篇
  1998年   52篇
  1997年   49篇
  1996年   48篇
  1995年   45篇
  1994年   46篇
  1993年   27篇
  1992年   4篇
  1991年   13篇
  1990年   11篇
  1989年   25篇
  1988年   23篇
  1987年   12篇
  1986年   15篇
  1985年   10篇
  1984年   7篇
  1983年   6篇
  1982年   10篇
  1981年   8篇
  1980年   10篇
  1979年   5篇
  1978年   6篇
  1977年   11篇
  1976年   6篇
  1975年   3篇
  1966年   1篇
排序方式: 共有859条查询结果,搜索用时 15 毫秒
61.
62.
BACKGROUND: Pantoprazole is a substituted benzimidazole which is a potent inhibitor of gastric acid secretion by its action upon H+, K+- ATPase. METHODS: Pantoprazole 40 mg and 80 mg were compared in a randomized double-blind study in 192 out-patients with stage II or III (Savary-Miller classification) reflux oesophagitis. Patients received either pantoprazole 40 mg (n = 97) or pantoprazole 80 mg (n = 95), once daily before breakfast for 4 weeks. Treatment was extended for a further 4 weeks if the oesophagitis had not healed. RESULTS: After 4 weeks complete healing of the reflux oesophagitis was seen in 78% of protocol-correct patients given pantoprazole 40 mg daily (n = 86), and in 72% in the 80 mg (n = 87) group. The cumulative healing rates after 8 weeks were 95 and 94%, respectively (P > 0.05, Cochran-Mantel- Haenszel), and time until healing of oesophagitis comparable in both groups. Differences between doses were also not significant in an intention-to-treat analysis. Both dosing schedules were well tolerated and the patients experienced remarkable symptom relief. No adverse event or changes in laboratory values of clinical significance could definitely be ascribed to the trial medication. CONCLUSION: The 40 mg pantoprazole dosage is comparable to 80 mg in reflux oesophagitis, both in efficacy and tolerability.  相似文献   
63.
64.
65.
目的探讨医源性脾脏损伤脾切除对结直肠癌切除患者术后长期生存的影响。方法对1990年1月1日至1999年12月31日10年间行结直肠癌手术切除并附带脾切除患者进行病例配对回顾研究。分析患者年龄、性别、依据美国麻醉学医师协会(ASA)标准评估的身体状况、疾病分期、手术类型及预后等资料。配对病例来自同一医疗中心,性别、年龄、疾病分期及手术类型完全相同。手术附带脾切除患者为试验组,未切脾者为对照组。结果55例患者行医源性脾切除术,对照组在年龄、性别、身体状况、疾病分期及手术类型上与之匹配。随访时间(从手术开始到患者死亡或者最后一次随访1为2~205个月(中位随访时间为43个月)。Cox比例危险度模型进行Kaplan-Meier法生存分析发现两组间差异有显著性意义,不切除脾脏对患者生存有利(危险度1.8,95%可信区间为1-3.3,P=0.0399),未切脾组与切脾组5年生存率分别为70%和47%,10年生存率分别为55%和38%。结论结直肠癌患者在行结肠或直肠切除时,因医源性脾脏损伤而切除脾脏者,预后较差。  相似文献   
66.
The effects of magnetic resonance (MR) pulse sequences and timing parameters on tumor-liver contrast were studied in an animal model of metastatic liver cancer. Six spin-echo (SE), three inversion-recovery (IR), and four gradient-echo (GRE) sequences were evaluated at 0.6 T before and after injection of super-paramagnetic iron oxide. GRE techniques, irrespective of echo time and flip angle, showed the greatest change in signal intensity (enhancement) of the liver after administration of iron oxide. Single-acquisition GRE sequences (16 seconds) matched the contrast-to-noise ratio (C/N) performance of the most effective 6.4-minute SE sequences. Multiexcitation GRE sequences showed tumor-liver C/Ns per unit time that were significantly (P less than .05) higher than those achieved with SE and IR sequences. GRE sequences, which recruit intravoxel dephasing as an additional source of transverse relaxation enhancement (T2*), show a higher C/N per unit time and in this respect seem superior to SE and IR sequences for MR imaging with superparamagnetic iron oxide.  相似文献   
67.
The C‐variant of a T‐13910C polymorphism (rs4988235; NT_022135.15:g.25316568G > A) upstream of the lactase phlorizin hydrolase (LPH) gene causes lactose intolerance. Association studies with differences in bone parameters and fracture risk have been inconclusive. The objective of this study was to examine the association of LPH rs4988235 with body height and bone parameters and calcium homeostasis in two elderly populations of Dutch Caucasians and assess interaction with vitamin D receptor (VDR) polymorphisms. Genotyping of LPH and VDR polymorphisms was performed in 6367 individuals from the Rotterdam Study and 844 from the Longitudinal Aging Study Amsterdam (LASA). Associations with age, height, weight, bone mineral density (BMD), skeletal morphometric parameters and serum vitamin D and calcium levels, and dietary calcium intake were assessed using ANOVA or analysis of covariance, and allele dose effect was assessed using linear regression analysis. Fracture risk was analyzed using Cox's proportional hazard regression analysis. Associations with body height (p = 2.7 × 10?8) and vertebral area (p = .048) found in the Rotterdam Study were explained by population stratification, as assessed by principal‐component analyses, and disappeared after additional adjustments. No associations with femoral neck or lumbar spine BMD or with fracture risk were detected. Calcium intake and serum ionized serum calcium were significantly lower in C‐homozygotes (p = 9.2 × 10?7, p = .02, respectively). For none of the parameters studied was interaction between the T‐13910C polymorphism and VDR block 5 haplotype 1 observed. We show that the C allele of the T‐13910C polymorphism causing lactose intolerance is associated with lower dietary calcium intake and serum calcium levels but not with BMD or fractures. The associations observed with height and vertebral area were the result of population stratification. This demonstrates the impact of population stratification and urges researchers to carefully take this into account in genetic associations, in particular, in dietary intake–related phenotypes, of which LPH and lactose intolerance are a strong example. © 2010 American Society for Bone and Mineral Research  相似文献   
68.

Objectives

The aim of the study was to describe growth and body composition changes in HIV‐positive children after they had initiated or changed antiretroviral therapy (ART) and to correlate these with viral, immune and treatment parameters.

Methods

Ninety‐seven prepubertal HIV‐positive children were observed over 48 weeks upon beginning or changing ART. Anthropometry and bioelectrical impedance analysis results were compared with results from the National Health and Nutrition Examination Survey 1999–2002 (NHANES) to generate z‐scores and with results for HIV‐exposed, uninfected children from the Women and Infants Transmission Study (WITS). Multivariate analysis was used to evaluate associations between growth and body composition and disease parameters.

Results

All baseline lean and fat mass measures were below those of controls from NHANES. Weight, height and fat free mass (FFM) index (FFM/height2) z‐scores increased over time (P=0.004, 0.037 and 0.027, respectively) and the waist:height ratio z‐score decreased (P=0.045), but body mass index and per cent body fat z‐scores did not change. Measures did not increase more than in uninfected WITS controls. In multivariate analysis, baseline height, mid‐thigh circumference and FFM z‐scores related to CD4 percentage (P=0.029, P=0.008 and 0.020, respectively) and change in FFM and FFM index z‐scores to CD4 percentage increase (P=0.010 and 0.011, respectively). Compared with WITS controls, baseline differences in height and mid‐thigh muscle circumference were also associated with CD4 percentage. Case–control differences in change in both subscapular skinfold (SSF) thickness and the SSF:triceps skinfold ratio were inversely associated with viral suppression. No measures related to ART class(es) at baseline or over time.

Conclusions

In these HIV‐positive children, beginning or changing ART was associated with improved growth and lean body mass (LBM), as indicated by FFM index. Height and LBM related to CD4 percentage at baseline and over time. Altered fat distribution and greater central adiposity were associated with detectable virus but not ART class(es) received.  相似文献   
69.

Background  

Mental health problems have become more common among young people over the last twenty years, especially in certain countries. The reasons for this have remained unclear. The hypothesis tested in this study is that national trends in young people's mental health are associated with national trends in young people's labour market.  相似文献   
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