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   2533篇
  免费   146篇
  国内免费   13篇
耳鼻咽喉   9篇
儿科学   131篇
妇产科学   16篇
基础医学   171篇
口腔科学   62篇
临床医学   209篇
内科学   999篇
皮肤病学   28篇
神经病学   66篇
特种医学   358篇
外科学   294篇
综合类   21篇
预防医学   71篇
眼科学   55篇
药学   77篇
中国医学   8篇
肿瘤学   117篇
  2023年   13篇
  2022年   19篇
  2021年   81篇
  2020年   50篇
  2019年   70篇
  2018年   72篇
  2017年   43篇
  2016年   58篇
  2015年   58篇
  2014年   86篇
  2013年   98篇
  2012年   121篇
  2011年   130篇
  2010年   99篇
  2009年   97篇
  2008年   89篇
  2007年   127篇
  2006年   100篇
  2005年   116篇
  2004年   106篇
  2003年   75篇
  2002年   56篇
  2001年   31篇
  2000年   43篇
  1999年   36篇
  1998年   105篇
  1997年   71篇
  1996年   80篇
  1995年   54篇
  1994年   55篇
  1993年   63篇
  1992年   13篇
  1991年   11篇
  1990年   14篇
  1989年   40篇
  1988年   25篇
  1987年   38篇
  1986年   23篇
  1985年   29篇
  1984年   23篇
  1983年   16篇
  1982年   22篇
  1981年   23篇
  1980年   28篇
  1979年   6篇
  1978年   16篇
  1977年   18篇
  1976年   20篇
  1975年   13篇
  1969年   2篇
排序方式: 共有2692条查询结果,搜索用时 15 毫秒
991.
There are numerous published studies establishing a link between reactive metabolite formation and toxicity of various drugs. Although the correlation between idiosyncratic reactions and reactive metabolite formation is not 1:1, the association between the two is such that many pharmaceutical companies now monitor for reactive metabolites as a standard part of drug candidate testing and selection. The most common method involves in vitro human microsomal incubations in the presence of a thiol trapping agent, such as glutathione (GSH), followed by LC/MS analysis. In this study, we describe several 2,7-disubstituted-pyrrolotriazine analogues that are extremely potent reactive metabolite precursors. Utilizing a UPLC/UV/MS method, unprecedented levels of GSH adducts were measured that are 5-10 times higher than previously reported for high reactive metabolite-forming compounds such as clozapine and troglitazone.  相似文献   
992.
993.
994.

Background

Changes in the burden of chronic obstructive pulmonary disease (COPD) and its exacerbations on primary health care are not well studied.

Aim

To identify trends in the prevalence of physician-diagnosed COPD and exacerbation rates by age, sex, and socioeconomic status in a general practice population.

Design of study

Trend analysis of COPD data from a 27-year prospective cohort of a dynamic general practice population.

Setting

Data were taken from the Continuous Morbidity Registration Nijmegen.

Method

For the period 1980–2006, COPD and COPD exacerbation data were extracted for patients aged ≥40 years. Data were standardised for the composition of the Continuous Morbidity Registration population in the year 2000. Regression coefficients for trends were estimated by sex, age, and socioeconomic status. Rate ratios were calculated for prevalence differences in different demographic subgroups.

Results

During the study period, the overall COPD prevalence decreased from 72.7 to 54.5 per 1000 patients per year. The exacerbation rate decreased from 44.1 to 31.5 per 100 patients, and the percentage of patients with COPD who had exacerbations declined from 27.6% to 21.0%. The prevalence of COPD increased significantly in women, in particular those aged ≥65 years with low socioeconomic status. Decreases in exacerbation rates and percentages of patients with exacerbations were independent of sex, age, and socioeconomic status.

Conclusion

The decline in COPD prevalence and exacerbation rates suggests a reduction of the burden on Dutch primary care. The increase of the prevalence in women indicates a need to focus on this particular subgroup in COPD management and research.  相似文献   
995.
996.
Objectives : We aimed to construct a predictive model for one‐year mortality in patients undergoing invasive coronary evaluation and to examine the impact of bivalirudin on survival according to the level of baseline risk. Background : Compared to heparin plus GP IIb/IIIa inhibitors (HEP/GPI), bivalirudin decreases bleeding complications in a range of clinical presentations. The impact of preprocedural risk assessment on survival and whether this is modified by bivalirudin, has not been investigated in detail. Methods : We examined patient‐level data from the REPLACE‐2, ACUITY, and HORIZONS‐AMI trials (n = 18,819) to construct a risk‐adjusted mortality model using baseline clinical variables. Results : One‐year mortality occurred in 287 patients (3.1%) assigned to bivalirudin and 336 patients (3.6%) assigned to HEP/GPI (HR 0.85; 95% CI, 0.73–1.00; P = 0.048). Using 11 highly significant predictors of mortality, we developed an integer‐risk score to classify patients into risk tertiles. High‐risk patients had a rate of 1‐year mortality over 9‐fold greater than low‐risk patients. Consequently, the absolute mortality reduction attributed to bivalirudin was more marked in high‐risk patients: 3.1% (?0.8% to 7.0%) in the overall cohort, 4.8% (0.5% to 9.2%) in the PCI cohort (P‐interaction versus intermediate and low risk categories, 0.09 and P = 0.02, respectively). Conclusions : In patients undergoing invasive coronary evaluation, 1‐year mortality can be predicted using baseline variables. Bivalirudin treatment (versus HEP/GPI) conferred a survival benefit. © 2015 Wiley Periodicals, Inc.  相似文献   
997.
998.
A C-T substitution at position 590 in the interleukin-4 (IL-4) gene is associated with increased production of IL-4. We sought to determine the associations between this polymorphism and susceptibility to brucellosis. DNA was extracted from the whole blood of 163 control individuals and 282 patients with brucellosis. A polymorphism in the IL-4 gene at position 590 from the promoter site was determined using an allele-specific PCR method. The prevalence of the T allele of IL-4 polymorphism was significantly higher in the patients group than in controls (28.9% vs 11.4%, p<0.004). Patients with brucellosis had a higher frequency of intermediate producer genotype (CT) (53.5% vs 22.7%, p<0.001) while low producer genotype (CC) was higher in the control group (77.3% vs 44.4%). Multiple logistic regression analysis demonstrated that patients who were heterozygous (CT) for interleukin-4 promoter polymorphism had a significantly higher risk for brucellosis with an odds ratio of 4.2 (95% CI 2.7-6.6, p<0.0001). Our findings demonstrate for the first time an association between IL-4 590 promoter polymorphism and contracting brucellosis in the Iranian population.  相似文献   
999.
1000.
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