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   742篇
  免费   30篇
  国内免费   36篇
耳鼻咽喉   3篇
儿科学   62篇
妇产科学   10篇
基础医学   68篇
口腔科学   17篇
临床医学   96篇
内科学   177篇
皮肤病学   8篇
神经病学   19篇
特种医学   166篇
外科学   50篇
综合类   17篇
预防医学   29篇
眼科学   8篇
药学   43篇
肿瘤学   35篇
  2024年   3篇
  2023年   3篇
  2021年   6篇
  2020年   4篇
  2019年   6篇
  2018年   13篇
  2017年   9篇
  2016年   4篇
  2015年   9篇
  2014年   17篇
  2013年   25篇
  2012年   15篇
  2011年   18篇
  2010年   51篇
  2009年   42篇
  2008年   17篇
  2007年   34篇
  2006年   13篇
  2005年   21篇
  2004年   6篇
  2003年   7篇
  2002年   11篇
  2001年   13篇
  2000年   5篇
  1999年   7篇
  1998年   48篇
  1997年   48篇
  1996年   47篇
  1995年   41篇
  1994年   42篇
  1993年   29篇
  1992年   3篇
  1991年   13篇
  1990年   12篇
  1989年   25篇
  1988年   25篇
  1987年   13篇
  1986年   15篇
  1985年   9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   10篇
  1976年   6篇
  1975年   3篇
  1931年   2篇
排序方式: 共有808条查询结果,搜索用时 15 毫秒
21.
Localization of vital components of neurological functioning has to be performed before epilepsy surgery can be considered in children with intractable epilepsy. This study reports the experience with the Wada procedure in very young children and/or developmentally delayed children with an a priori considerable chance of failing the procedure. The aim of this study was to indicate the applicability of this procedure in this patient group. The Wada procedure is described in 16 children under 10 years of age and/or have intelligence quotient scores below 50 and/or are critically ill and/or are behaviourally disturbed. Information on motor, language and memory functioning is obtained in respectively 13/15, 9/13, and 5/11 children. Nine children underwent epilepsy surgery without postoperative impairment of neurological functioning. In five children epilepsy surgery was not performed because of the results of the Wada procedure or the lack of information during the Wada procedure. One child became seizure-free before surgery. Even in very young, developmentally delayed or behaviourally disturbed children, the Wada test can provide important information with respect to the decision pro or contra epilepsy surgery.  相似文献   
22.
Aim: To describe gut colonization in preterm infants using standard culture and 16S gene rRNA profiling, exploring differences in healthy infants and those who developed NEC/late onset sepsis (LOS). Methods: Ninety‐nine stools from 38 infants of median 27‐week gestation were cultured; 44 stools from 27 infants had their microbial profiles determined by 16S. Ordination analyses explored effects of patient variables on gut communities. Results: Standard microbiological culture identified a mean of two organisms (range 0–7), DGGE 12 (range 3–18) per patient. Enterococcus faecalis and coagulase negative staphylococci (CONS) were most common by culture (40% and 39% of specimens). Meconium was not sterile. No fungi were cultured. Bacterial community structures in infants with NEC and LOS differed from healthy infants. Infants who developed NEC carried more CONS (45% vs 30%) and less Enterococcus faecalis (31% vs 57%). 16S identified Enterobacter and Staphylococcus presence associated with NEC/LOS, respectively. Conclusions: Important differences were found in the gut microbiota of preterm infants who develop NEC/LOS. The relationship of these changes to current practices in neonatal intensive care requires further exploration.  相似文献   
23.
24.
25.
Background: Ventilator frequency is one of the determinants of tidal volume delivery during high‐frequency ventilation. Clinicians increasingly use data on ventilator displays to inform their decisions. Aim: To measure the frequencies delivered by the Dräger Babylog 8000plus ventilator when used in high‐frequency mode. Methods: Ventilator waveforms using a test lung were recorded at the full range of settings 5–20 Hz using Spectra software at 1000 Hz. The changes in frequency produced by a 1‐ Hz change in set frequency were calculated. Actual and displayed frequencies were compared. Results: For settings up to 12 Hz, median (range) difference between set and delivered frequencies was 0 (?0.4 to +0.1) Hz. Above 12 Hz, delivered frequency varied by ?0.3 (?1.9 to +0.3) Hz. For 1‐ Hz changes in frequency settings, in the range 5–12 Hz, 1‐ Hz changes produced a change in delivered frequency of 1.0 (0.6–1.4) Hz. Above 12 Hz, the corresponding changes were 0.7 (0–2.9) Hz. The ventilator displays the set frequency during operation rather than the delivered frequency. Conclusion: At 12 Hz and below, the differences between set and delivered frequencies were relatively small compared with those at 13 Hz and higher. Above 13 Hz, the difference between set and delivered frequencies was up to 2.9 Hz. Some frequency setting changes did not result in a change in delivered frequency.  相似文献   
26.
27.
28.
29.
This study investigated the effects and possible targets of Fructus Broussonetiae extract,a traditional Chinese medicinal herb,on a model of Alzheimer’s disease induced by beta-amyloid peptide 25-35 and D-galactose.The results revealed that intragastric administration of Fructus Broussonetiae significantly increased the expression of immunoglobulin-binding protein,a key factor in the endoplasmic reticulum stress-signaling pathway in rat hippocampus.In contrast,the treatment significantly decreased expression levels of PKR-like endoplasmic reticulum kinase and C/EBP homologous protein,and substantially improved learning,memory and spatial recognition dysfunction in rats.This evidence indicates that Fructus Broussonetiae extract improves spatial learning and memory abilities in rats by affecting the regulation of hippocampal endoplasmic reticulum stress and activation of the apoptosis pathway.  相似文献   
30.
Fraser  CC; Eaves  CJ; Szilvassy  SJ; Humphries  RK 《Blood》1990,76(6):1071-1076
A large number of biologic, technological, and clinical studies await the development of procedures that will allow totipotent hematopoietic stem cells to be expanded in vitro. Previous work has suggested that hematopoiesis can be reconstituted using transplants of cells from long- term marrow cultures. We have used retrovirus mediated gene transfer to demonstrate that marked totipotent hematopoietic stem cells are both maintained and can be amplified in such cultures, and then subsequently regenerate and sustain lympho-myeloid hematopoiesis in irradiated recipients. Marrow cells from 5-fluorouracil-treated male mice were infected with a recombinant virus carrying the neomycin resistence gene and seeded onto irradiated adherent layers of pre-established, long- term marrow cultures of female origin. At 4 weeks, cells from individual cultures were transplanted into single or multiple female recipients. Southern blot analysis of hematopoietic tissue 45 days posttransplantation showed retrovirally marked clones common to lymphoid and myeloid tissues in 14 of 23 mice examined. Strikingly, for 3 of 4 long-term cultures, multiple recipients of cells from a single flask showed marrow and thymus repopulation with the same unique retrovirally marked clone. These results establish the feasibility of retroviral-marking techniques to demonstrate the maintenance of totipotent lympho-myeloid stem cells for at least 4 weeks in the long- term marrow culture system and provide the first evidence of their proliferation in vitro. Therefore, such cultures may serve as a starting point for identifying factors that stimulate totipotent hematopoietic stem cell expansion.  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