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   38144篇
  免费   2690篇
  国内免费   160篇
耳鼻咽喉   285篇
儿科学   1111篇
妇产科学   749篇
基础医学   4707篇
口腔科学   748篇
临床医学   3664篇
内科学   8655篇
皮肤病学   566篇
神经病学   3906篇
特种医学   1164篇
外国民族医学   1篇
外科学   5595篇
综合类   545篇
一般理论   31篇
预防医学   3089篇
眼科学   742篇
药学   2645篇
  1篇
中国医学   54篇
肿瘤学   2736篇
  2023年   237篇
  2022年   354篇
  2021年   727篇
  2020年   487篇
  2019年   713篇
  2018年   821篇
  2017年   636篇
  2016年   689篇
  2015年   828篇
  2014年   1186篇
  2013年   1646篇
  2012年   2451篇
  2011年   2741篇
  2010年   1515篇
  2009年   1406篇
  2008年   2317篇
  2007年   2625篇
  2006年   2465篇
  2005年   2568篇
  2004年   2321篇
  2003年   2213篇
  2002年   2045篇
  2001年   365篇
  2000年   296篇
  1999年   419篇
  1998年   457篇
  1997年   349篇
  1996年   341篇
  1995年   282篇
  1994年   253篇
  1993年   279篇
  1992年   269篇
  1991年   267篇
  1990年   210篇
  1989年   183篇
  1988年   197篇
  1987年   186篇
  1986年   146篇
  1985年   207篇
  1984年   273篇
  1983年   235篇
  1982年   261篇
  1981年   261篇
  1980年   254篇
  1979年   137篇
  1978年   153篇
  1977年   144篇
  1976年   137篇
  1974年   109篇
  1973年   93篇
排序方式: 共有10000条查询结果,搜索用时 13 毫秒
991.
992.
993.
994.
995.
996.
997.
OBJECTIVES: We compared outcomes in patients with non-ST-segment elevation acute coronary syndromes (ACS) according to the degree of cardiac troponin I (cTnI) elevation. BACKGROUND: Controlled trials of high-risk patients have found that troponin elevations identify an even higher risk subset. It is unclear whether outcomes are similar among a lower risk, heterogeneous patient group. Also, few studies have reported outcomes other than myocardial infarction (MI) or death, based on the peak troponin value. METHODS: Consecutively, admitted patients without ST-segment elevation on the initial electrocardiogram underwent serial marker sampling using creatine kinase (CK), CK-MB fraction, and cTnI. Patients were grouped according to peak cTnI: negative = no detectable cTnI; low = peak greater than the lower limit of detectability but less than the optimal diagnostic value; intermediate = peak greater than or equal to the optimal diagnostic value but less than the manufacturer's suggested upper reference limit (URL); and high = peak greater than or equal to the URL. Thirty-day outcomes included cardiac death, MI based on CK-MB, revascularization, significant disease, and a reversible defect on stress testing. Six-month mortality was also determined. Negative evaluations for ischemia included nonsignificant disease, no reversible stress defect, and negative rest perfusion imaging. RESULTS: Of the 4,123 patients admitted, 893 (22%) had detectable cTnI values. Cardiac events and positive test results at 30 days and 6-month mortality increased significantly with increasing cTnI values. Negative evaluations for ischemia were significantly and inversely related to peak cTnI values. Although adverse events were significantly more common in patients with a low cTnI value than in those with negative cTnI, negative evaluations for ischemia were frequent. CONCLUSIONS: Increased cTnI values are associated with worse outcomes. Although low cTnI values are associated with adverse events, they do not have the same implication as higher cTnI values, and nonischemic evaluations are frequent.  相似文献   
998.
999.
Current clinical judgment in bladder cancer (BC) relies primarily on pathological stage and grade. We investigated whether a molecular classification of tumor cell differentiation, based on a developmental biology approach, can provide additional prognostic information. Exploiting large preexisting gene-expression databases, we developed a biologically supervised computational model to predict markers that correspond with BC differentiation. To provide mechanistic insight, we assessed relative tumorigenicity and differentiation potential via xenotransplantation. We then correlated the prognostic utility of the identified markers to outcomes within gene expression and formalin-fixed paraffin-embedded (FFPE) tissue datasets. Our data indicate that BC can be subclassified into three subtypes, on the basis of their differentiation states: basal, intermediate, and differentiated, where only the most primitive tumor cell subpopulation within each subtype is capable of generating xenograft tumors and recapitulating downstream populations. We found that keratin 14 (KRT14) marks the most primitive differentiation state that precedes KRT5 and KRT20 expression. Furthermore, KRT14 expression is consistently associated with worse prognosis in both univariate and multivariate analyses. We identify here three distinct BC subtypes on the basis of their differentiation states, each harboring a unique tumor-initiating population.  相似文献   
1000.
Genotyping of Mycobacterium tuberculosis isolates is a useful tool for epidemiological control of tuberculosis (TB) and phylogenetic exploration of the pathogen. There is a lack of information on the discriminatory power of standard 24-locus mycobacterial interspersed repetitive unit (MIRU) - variable number tandem repeats (VNTR) in India, which has the highest tuberculosis (TB) burden worldwide. Therefore, we assessed its utility on 69 M.?tuberculosis (MTB) isolates from patients with extrapulmonary tuberculosis, in comparison to standard insertion sequence (IS) 6110-Restriction fragment length polymorphism (RFLP) fingerprinting and spoligotyping. IS6110-RFLP (HGDI, 0.9987) identified a single cluster of 3 (4.3%) single-copy IS6110 isolates. Spoligotyping showed 69.5% clustering (HGDI, 0.8857). In contrast, MIRU-VNTR analysis identified 69 (100%) unique strains (HGDI, 1.0000). Within the study limits, this observed high discriminatory power suggests that 24-locus MIRU-VNTR genotyping could potentially be used to study long-term transmission of MTB infection in Mumbai. Moreover, high congruence between the MIRU-VNTR-based and spoligotyping-based strain groupings suggests that CAS, EAI and Beijing are the predominant strain lineages in the Mumbai TB patient population. The Beijing lineage isolates were found to be more significantly associated with multi-drug resistance (p?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