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   4650篇
  免费   338篇
  国内免费   20篇
耳鼻咽喉   19篇
儿科学   149篇
妇产科学   109篇
基础医学   713篇
口腔科学   128篇
临床医学   359篇
内科学   1118篇
皮肤病学   216篇
神经病学   534篇
特种医学   44篇
外科学   324篇
综合类   21篇
预防医学   397篇
眼科学   145篇
药学   371篇
中国医学   33篇
肿瘤学   328篇
  2023年   35篇
  2022年   59篇
  2021年   170篇
  2020年   101篇
  2019年   163篇
  2018年   178篇
  2017年   127篇
  2016年   147篇
  2015年   156篇
  2014年   216篇
  2013年   253篇
  2012年   439篇
  2011年   422篇
  2010年   239篇
  2009年   189篇
  2008年   341篇
  2007年   288篇
  2006年   271篇
  2005年   285篇
  2004年   255篇
  2003年   222篇
  2002年   230篇
  2001年   12篇
  2000年   9篇
  1999年   30篇
  1998年   29篇
  1997年   24篇
  1996年   21篇
  1995年   13篇
  1994年   8篇
  1993年   12篇
  1992年   9篇
  1991年   7篇
  1990年   4篇
  1989年   2篇
  1988年   2篇
  1987年   6篇
  1986年   6篇
  1983年   2篇
  1982年   5篇
  1981年   4篇
  1980年   2篇
  1978年   3篇
  1977年   1篇
  1976年   1篇
  1974年   2篇
  1973年   1篇
  1971年   1篇
  1970年   1篇
  1967年   1篇
排序方式: 共有5008条查询结果,搜索用时 31 毫秒
991.

Introduction

Delirium is a frequent source of morbidity in intensive care units (ICUs). Most data on its epidemiology is from single-center studies. Our aim was to conduct a multicenter study to evaluate the epidemiology of delirium in the ICU.

Methods

A 1-day point-prevalence study was undertaken in 104 ICUs from 11 countries in South and North America and Spain.

Results

In total, 975 patients were screened, and 497 fulfilled inclusion criteria and were enrolled (median age, 62 years; 52.5% men; 16.7% and 19.9% for ICU and hospital mortality); 64% were admitted to the ICU because of medical causes, and sepsis was the main diagnosis (n = 76; 15.3%). In total, 265 patients were sedated with the Richmond agitation and sedation scale (RASS) deeper than -3, and only 232 (46.6%) patients could be evaluated with the confusion-assessment method for the ICU. The prevalence of delirium was 32.3%. Compared with patients without delirium, those with the diagnosis of delirium had a greater severity of illness at admission, demonstrated by higher sequential organ-failure assessment (SOFA (P = 0.004)) and simplified acute physiology score 3 (SAPS3) scores (P < 0.0001). Delirium was associated with increased ICU (20% versus 5.7%; P = 0.002) and hospital mortality (24 versus 8.3%; P = 0.0017), and longer ICU (P < 0.0001) and hospital length of stay (LOS) (22 (11 to 40) versus 7 (4 to 18) days; P < 0.0001). Previous use of midazolam (P = 0.009) was more frequent in patients with delirium. On multivariate analysis, delirium was independently associated with increased ICU mortality (OR = 3.14 (1.26 to 7.86); CI, 95%) and hospital mortality (OR = 2.5 (1.1 to 5.7); CI, 95%).

Conclusions

In this 1-day international study, delirium was frequent and associated with increased mortality and ICU LOS. The main modifiable risk factors associated with the diagnosis of delirium were the use of invasive devices and sedatives (midazolam).  相似文献   
992.
Chagas' disease is a prevalent disease in South America that is thought to have an autoimmune etiology. We previously identified human Cha as a new autoantigen recognized by chagasic sera. Those sera recognized an epitope spanning amino acids 120 to 129 of Cha, named R3. In the present study we have used the synthetic R3 peptide for the detection of serum immunoglobulin G antibodies from patients at different stages of Chagas' disease, including a therapeutically treated group. The immunoreactivity with R3 by enzyme-linked immunosorbent assay (ELISA) showed 92.4% sensitivity and 100% specificity for Chagas' disease sera. This sensitivity and specificity were higher than for any other autoantigen described to date. No anti-R3 antibodies were detected in sera from Leishmania-infected or idiopathic dilated cardiomyopathy patients or healthy controls from the same areas. Moreover, anti-R3 antibody reactivity detected by ELISA correlated with conventional serological tests as indirect immunofluorescence and ELISA assays with Trypanosoma cruzi extracts and other diagnostic tests as indirect hemagglutination. The levels of anti-R3 antibodies increased with progression and symptomatology of Chagas' disease. More interestingly, a statistically significant fall in anti-R3 antibody titer was observed in patients treated with antiparasitic drugs. Those results suggest that the presence of anti-R3 antibodies is a highly specific marker of Chagas' disease and that R3 ELISA could be helpful in the diagnosis and monitoring of this disease.  相似文献   
993.
Chronic ethanol treatment and withdrawal from alcohol decrease the synthesis and expression of neuropeptides in the hypothalamic suprachiasmatic nucleus. Given the existing evidence that neurotrophins modulate the synthesis and expression of neurotransmitters/neuromodulators in the mature brain, we have hypothesized that such alterations might result from the reduced biological activity or brain content of neurotrophic factors. To test this possibility, nerve growth factor (NGF) was delivered intraventricularly, over a 4-week period, to rats submitted to ethanol treatment for 6 months and to withdrawn rats. Vasopressin (AVP) and vasoactive intestinal polypeptide (VIP), and the respective mRNAs were detected by immunocytochemistry and in situ hybridization histochemistry, and their levels estimated using stereological methods and densitometry. In ethanol-treated and withdrawn rats, NGF produced increases in the number of AVP- and VIP-immunostained neurons to values identical to those of controls. Corresponding variations were detected in AVP and VIP mRNA levels, which indicates that NGF restored the expression of AVP and VIP by enhancing neuropeptide synthesis. These findings show that NGF can correct the changes induced by chronic ethanol treatment and withdrawal in the gene expression and protein content of the neuropeptides synthesized by suprachiasmatic neurons. They also reveal that NGF plays an important role in the maintenance of the neurochemical phenotype of the suprachiasmatic nucleus in the adult rat. Because suprachiasmatic neurons do not express trkA, NGF might have exerted its effects either through direct signalling of suprachiasmatic neurons via p75NTR activation or, indirectly, by enhancing the activity of the cholinergic and/or glutamatergic afferents to the suprachiasmatic nucleus, or both.  相似文献   
994.
995.
Skin tags are skin-colored, pedunculated tumors with a smooth surface. Histologically are composed by loose collagen fibers and dilated capillaries. Giant skin tags are reported rarely in the literature. We present the case of two giant skin tags on labium majus. To our knowledge, these are the largest skin tags reported.  相似文献   
996.
997.
998.
999.
The present review gives a perspective on the Aurora kinase family members, their function in normal cells, their role in cancer progression as well as their potential as target for anticancer treatment. Mitosis has been an important target for anticancer therapy development, leading to some specific drugs mainly addressing Tubulines, as a key structure of the mitotic spindle. Vinca alkaloids, taxanes or epotilones are good examples of conventionally developed antimitotic agents. However, novel classes of antineoplastic drugs are being studied, targeting the regulatory system that controls functional aspects of mitosis, such as Aurora or Polo-like kinases or Kinespondin inhibitors. The specific role of the different Aurora kinase proteins as regulator enzymes of the mitotic process in normal cells is discussed. Some of the mechanisms that link Aurora overexpression with cancer are also considered. Thereafter, the clinical and preclinical development of the different Aurora kinase inhibitors is presented. This is nowadays a very active area of therapeutic research and at least, sixteen new compounds are being studied as potential antineoplastic drugs. Most of them are in a very early phase of clinical development. However, we summarized the most recently published findings related with these drugs: main characteristics, way of administration, dose limiting toxicities and recommended doses for further studies. Another important aspect in Aurora kinase inhibition is the study and validation of potential biomarkers to optimize the clinical development. Several studies included pharmacodynamic assessments in normal blood cells, skin or/and tumor biopsies. Several proposals included a higher mitotic index, a decreased number of mitosis with bipolar spindles or normal alignment of chromosomes and inhibition of histone H3 phosphorylation. Future strategies and challenges for trials with Aurora kinase inhibitors are also discussed.  相似文献   
1000.
Previous studies have shown that the spatial extent of crowding in peripheral vision is reduced when a target letter and its flanking letters have opposite contrast polarity. We have examined if this reduction in crowding leads to improved reading performance. We compared the spatial extent of crowding, visual-span profiles (plots of letter-recognition accuracy versus letter position), and reading speed at 10° inferior visual field, using white letters, black letters, or mixtures of white and black letters, presented on a mid-gray background. Consistent with previous studies, the spatial extent of crowding was reduced when the target and flanking letters had opposite contrast polarity. However, using mixed contrast polarity did not lead to improvements in visual-span profiles or reading speed.  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