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   2126篇
  免费   176篇
  国内免费   105篇
耳鼻咽喉   20篇
儿科学   55篇
妇产科学   42篇
基础医学   343篇
口腔科学   43篇
临床医学   294篇
内科学   490篇
皮肤病学   25篇
神经病学   174篇
特种医学   129篇
外科学   177篇
综合类   41篇
预防医学   187篇
眼科学   12篇
药学   248篇
中国医学   1篇
肿瘤学   126篇
  2023年   7篇
  2022年   15篇
  2021年   27篇
  2020年   32篇
  2019年   26篇
  2018年   52篇
  2017年   33篇
  2016年   36篇
  2015年   37篇
  2014年   62篇
  2013年   103篇
  2012年   107篇
  2011年   134篇
  2010年   75篇
  2009年   72篇
  2008年   91篇
  2007年   152篇
  2006年   94篇
  2005年   108篇
  2004年   97篇
  2003年   89篇
  2002年   104篇
  2001年   61篇
  2000年   70篇
  1999年   67篇
  1998年   61篇
  1997年   53篇
  1996年   61篇
  1995年   39篇
  1994年   38篇
  1993年   25篇
  1992年   48篇
  1991年   42篇
  1990年   35篇
  1989年   37篇
  1988年   30篇
  1987年   24篇
  1986年   26篇
  1985年   16篇
  1984年   18篇
  1983年   11篇
  1982年   10篇
  1981年   6篇
  1980年   7篇
  1979年   8篇
  1978年   8篇
  1977年   7篇
  1976年   7篇
  1972年   5篇
  1967年   4篇
排序方式: 共有2407条查询结果,搜索用时 15 毫秒
31.
32.
The fragile X syndrome is the most frequent cause of inheritedmental retardation. The molecular mechanism of the disorderis based on the expansion of a CGG repeat in the 5' UTR of theFMR1 gene In the majority of fragile X patients. The instabilityof this CGG repeat containing region is not restricted to theCGG repeat Itself but expands to the flanking region as well.We describe four unrelated fragile X patients that are mosaicfor both a full mutation and a small deletion in the CGG repeatcontaining region. Sequence analysis of the regions surroundingthe deletions showed that both the (CGG)n repeat and some flankingsequences were missing in all four patients. The 5' breakpointsof the deletions were found to be located between 75–53bp proximal to the CGG repeat. This suggests the presence ofa hot spot region for deletions in the CGG repeat region ofthe FMR1 gene and emphasizes the instability of this regionIn the presence of an expanded CGG repeat.  相似文献   
33.
A dipstick assay for the detection of brucella-specific immunoglobulin M antibodies was evaluated with 707 sera from 247 laboratory-confirmed brucellosis patients and 342 control sera from brucellosis-free individuals. These sera were collected from six different countries. The assay was found to be highly sensitive and specific. In addition, the test is easy to use and does not require specialized training or equipment, and the components are stable without a requirement for refrigeration. All of these factors make the test ideal for developing countries and rural settings.  相似文献   
34.
The overall prevalence of the fragile X [fra(X)] mutation, as determined by population studies, is approximately 1 in 850 [Gustavson et al., 1986; Webb et al., 1986]. This prevalence suggests a very high mutation rate which, in turn, suggests that many patients have to represent sporadic cases. In order to obtain an accurate estimate of the proportion of sporadic cases, we performed genealogic, cytogenetic and DNA linkage studies as well as direct analysis of the CGG repeat in relatives of 84 fra(X) probands. We did not find any evidence for the presence of sporadic cases. In 11 probands consanguinity could be proven by the detection of common ancestors, in 5 related families up to 9 generations ago. In the other 6 related families the mutation could be traced back 4-6 generations. In 3 or more generation families we were able to demonstrate that half of the probands carried the grandpaternal fra(X) gene. These results imply that rather than a high mutation rate, both Normal Transmitting Males (NTM's) and mentally normal female carriers contribute considerably to the high prevalence of the fra(X) syndrome.  相似文献   
35.
BackgroundSigns of the systemic inflammatory response syndrome (SIRS) – fever (or hypothermia), tachycardia and tachypnoea – are used in the hospital setting to identify patients with possible sepsis.ObjectivesTo determine how frequently abnormalities in the vital signs of SIRS are present in adult out-of-hours (OOH) primary care patients with suspected infections and assess the association with acute hospital referral.MethodsWe conducted a cross-sectional study at the OOH GP cooperative in Nijmegen, the Netherlands, between August and October 2015. GPs were instructed to record the body temperature, heart rate and respiratory rate of all patients with suspected acute infections. Vital signs of SIRS, other relevant signs and symptoms, and referral state were extracted from the electronic registration system of the OOH GP cooperative retrospectively. Logistic regression analysis was used to evaluate the association between clinical signs and hospital referral.ResultsA total of 558 patients with suspected infections were included. At least two SIRS vital signs were abnormal in 35/409 (8.6%) of the clinic consultations and 60/149 (40.3%) of the home visits. Referral rate increased from 13% when no SIRS vital sign was abnormal to 68% when all three SIRS vital signs were abnormal. Independent associations for referral were found for decreased oxygen saturation, hypotension and rapid illness progression, but not for individual SIRS vital signs.ConclusionAlthough patients with abnormal vital signs of SIRS were referred more often, decreased oxygen saturation, hypotension and rapid illness progression seem to be most important for GPs to guide further management.  相似文献   
36.
A growing body of evidence has demonstrated the prognostic significance of sarcopenia in surgical patients as an independent predictor of postoperative complications and outcomes. These included an increased risk of total complications, major complications, re-admissions, infections, severe infections, 30 d mortality, longer hospital stay and increased hospitalization expenditures. A program to enhance recovery after surgery was meant to address these complications; however, compliance to the program since its introduction has been less than ideal. Over the last decade, the concept of prehabilitation, or “pre-surgery rehabilitation”, has been discussed. The presurgical period represents a window of opportunity to boost and optimize the health of an individual, providing a compensatory “buffer” for the imminent reduction in physiological reserve post-surgery. Initial results have been promising. We review the literature to critically review the utility of prehabilitation, not just in the clinical realm, but also in the scientific realm, with a resource management point-of-view.  相似文献   
37.
Dendritic cell-mediated T cell polarization   总被引:24,自引:0,他引:24  
Effective defense against diverse types of micro-organisms that invade our body requires specialized classes of antigen-specific immune responses initiated and maintained by distinct subsets of effector CD4+ T helper (Th) cells. Excessive or detrimental (e.g., autoimmune) responses by effector T cells are controlled by regulatory T cells. The optimal balance in the development of the different types of effector and regulatory Th cells is orchestrated by dendritic cells (DC). This review discusses the way DC adapt the T cell response to the type of pathogen, focusing on the tools that DC use in this management of the T cell response.  相似文献   
38.
Summary The absorption and diuretic effect of furosemide 40 mg alone (F), and of the free (F+T) and the fixed (FT) combinations of furosemide 40 mg and triamterene 50 mg have been compared in 12 healthy young men.A slight reduction in the area under the concentration-time curve (AUC) of plasma furosemide was found for the fixed combination (AUC480) F 2.58 g · h · ml–1; F+T 2.46 g · h · ml–1; FT 1.97 g · h · ml–1. There was a significant reduction in the AUC480 of plasma triameterene (F+T 204.9 g · h · l–1; FT 130.2 g · h · l–1). Sodium excretion after F+T and FT was more pronounced than after F (F+T 302 mmol; FT 311 mmol; F 259 mmol). When compared to F alone, there was a reduction in the 24-hour potassium excretion after F+T as well as after FT (F 121 mmol; F+T 104 mmol; FT 107 mmol).It is concluded that the absorption of triamterene was significantly reduced after ingestion of the fixed combination tablet. However, in healthy male adults this had no influence on its natriuretic and potassium-sparing effect as compared to the free combination.  相似文献   
39.
Internet网上细胞凋亡研究的信息资源及其利用   总被引:1,自引:0,他引:1  
杨连君  王文亮 《医学争鸣》2000,21(11):229-230
0 引言  Internet网上含有丰富的信息资源 ,科研人员可以通过 Internet网了解其所研究领域的最新发展动态 ,获取全面和系统的科研信息 ,有利于进行学术交流[1 ] .然而网上信息浩如烟海 ,当检索某一专门领域的资料时 ,有时无从下手 .我们在科研实践中对 Internet网上主要的细胞凋亡研究信息资源及其查找方法进行了归纳 .1 细胞凋亡专业网站1. 1  The Cell death society (http:/ / www.celldeath-apoptosis.org) 为美国细胞死亡学会主办 ,概括了细胞凋亡和程序性细胞死亡研究的各个领域 ,包括与细胞凋亡有关的各种疾病 .可以免费注册…  相似文献   
40.
Severe degenerative features of the nervous system of a hitherto unknown kind, associated with a neuromuscular disorder with histopathological features of congenital muscular dystrophy, are reported in two female siblings. The clinical profile was characterized by generalized hypotonia followed by spastic tetraplegia, contractures, polyneuropathy, lack of cognitive development and progressive microcephaly. There was no involvement of the eyes. Neuropathological examination of the brain of one sibling, who died at the age of 30 months, revealed subtotal loss of neurons in the cerebral and cerebellar cortex and in the ventral pons, and secondary loss of myelin in the cerebral and cerebellar subcortical white matter. Sural nerve biopsy in the other sibling, who had a similar neurological affection, showed a lack of large myelinated fibers.This investigation is part of the research program Disorders of the Neuromuscular System of the University of Nijmegen  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