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   2020篇
  免费   155篇
  国内免费   63篇
耳鼻咽喉   37篇
儿科学   145篇
妇产科学   79篇
基础医学   262篇
口腔科学   46篇
临床医学   164篇
内科学   314篇
皮肤病学   44篇
神经病学   104篇
特种医学   312篇
外科学   241篇
综合类   69篇
预防医学   118篇
眼科学   13篇
药学   183篇
肿瘤学   107篇
  2022年   10篇
  2021年   17篇
  2020年   10篇
  2019年   19篇
  2018年   35篇
  2017年   16篇
  2016年   23篇
  2015年   32篇
  2014年   46篇
  2013年   53篇
  2012年   59篇
  2011年   70篇
  2010年   46篇
  2009年   51篇
  2008年   54篇
  2007年   96篇
  2006年   55篇
  2005年   67篇
  2004年   58篇
  2003年   57篇
  2002年   51篇
  2001年   68篇
  2000年   68篇
  1999年   66篇
  1998年   71篇
  1997年   81篇
  1996年   77篇
  1995年   83篇
  1994年   53篇
  1993年   64篇
  1992年   49篇
  1991年   52篇
  1990年   52篇
  1989年   89篇
  1988年   64篇
  1987年   52篇
  1986年   48篇
  1985年   53篇
  1984年   25篇
  1983年   20篇
  1982年   25篇
  1981年   26篇
  1980年   24篇
  1979年   16篇
  1978年   9篇
  1977年   17篇
  1976年   15篇
  1975年   8篇
  1973年   5篇
  1969年   4篇
排序方式: 共有2238条查询结果,搜索用时 15 毫秒
41.
The major surface glycoprotein (MSG) of Pneumocystis carinii f. sp. carinii consists of a heterogeneous family of proteins that are encoded by approximately 100 unique genes. A genomic expression library was screened with a panel of MSG-specific monoclonal antibodies (MAbs) to identify conserved and rare epitopes. All of the antibodies reacted with epitopes that are encoded within the 5′ end of MSG. The results from the expression screening identified antibodies that recognize highly conserved, moderately conserved, and rare epitopes. Four MAbs (MAbs RA-F1, RA-E7, RA-G10, and RB-E3) reacted with a maltose binding protein–MSG-B fusion protein (MBPMSG-B41–1065) by immunoblotting and enzyme-linked immunosorbent assay. Three of the MAbs (MAbs RA-F1, RA-G10, and RA-E7) reacted with the same continuous epitope that was localized to amino acids 278 to 290 of MSG-B. Comparison of the sequence of the RA-F1-, RA-G10-, and RA-E7-reactive epitope to the deduced amino acid sequences of multiple MSGs demonstrated that it is highly conserved. The reactivity of RB-E3 with MSG-B was shown to be dependent on amino acids 184 to 192, which may comprise a portion of a discontinuous epitope.  相似文献   
42.
43.
Lung carcinoids occur sporadically and rarely in association with multiple endocrine neoplasia type 1 (MEN1). There are no well defined genetic abnormalities known to occur in these tumors. We studied 11 sporadic lung carcinoids for loss of heterozygosity (LOH) at the locus of the MEN1 gene on chromosome 11q13, and for mutations of the MEN1 gene using dideoxy fingerprinting. Additionally, a lung carcinoid from a MEN1 patient was studied. In four of 11 (36%) sporadic tumors, both copies of the MEN1 gene were inactivated. All four tumors showed the presence of a MEN1 gene mutation and loss of the other allele. Observed mutations included a 1 bp insertion, a 1 bp deletion, a 13 bp deletion and a single nucleotide substitution affecting a donor splice site. Each mutation predicts truncation or potentially complete loss of menin. The remaining seven tumors showed neither the presence of a MEN1 gene mutation nor 11q13 LOH. The tumor from the MEN1 patient showed LOH at chromosome 11q13 and a complex germline MEN1 gene mutation. The data implicate the MEN1 gene in the pathogenesis of sporadic lung carcinoids, representing the first defined genetic alteration in these tumors.   相似文献   
44.
IntroductionThe difference in outcome between right (RCD) and left colonic diverticulitis (LCD) is not well established. The aim of this study was to analyse the presentation and surgical outcome of RCD versus left-sided disease following emergency surgery.MethodWe conducted a retrospective review of patients presenting with acute diverticulitis over a 10-year period from 2004 to 2014 to a tertiary unit. Patient demographics, Hinchey classification, need for emergency surgery, perioperative outcome and recurrence were evaluated.ResultsIn total 360 patients presented with acute diverticulitis, 218 (61%) were right-sided and 142 (39%) were left-sided. The mean age (57 yrs vs 68 yrs) and median length of stay (4 days vs 5 days) were significantly less in RCD (p < 0.001). The need for emergency surgery was similar between RCD and LCD (30.7% vs 23.2%, p = 0.12). Sixty-seven (31%) patients with RCD required emergency surgery, 42 (62.7%) of these were based on a presumptive diagnosis of appendicitis and underwent laparoscopic appendicectomy only. Operative morbidity (10.4% vs 51.5%, p < 0.001) and mortality were significantly higher in LCD (1.5% v 15.2%, p = 0.007). Subgroup analysis of non-appendicectomy, RCD patients, showed LCD were more likely to require surgery (11.5% vs 23.2%, p = 0.003). There was no difference in recurrence (p = 0.6).ConclusionRight colonic diverticulitis patients are younger and disease course is more benign compared to LCD. Presentation can be confused with appendicitis without proper imaging. In the rare cases where emergency surgery is required, RCD is associated with a lower operative morbidity and mortality compared to left-sided disease.  相似文献   
45.
46.
47.
0 引言 人类免疫缺陷病毒 (human immunodeficiencyvirus,HIV) - 1编码的反式激活蛋白 TAT具有独特的跨膜运转方式 ,而且有转导速度快 ,效率高的特点 ,被称为蛋白转导结构域 (protein transduction domain,PTD) [1 ,2 ] .本研究用PCR扩增了慢性粒细胞白血病慢粒 bcr/ abl融合蛋白的基因片段 ,在其 5′端融合 PTD结构域的编码区后在大肠杆菌中进行了表达 .表达产物经纯化后 ,加入培养的 HL 6 0细胞 ,表达的蛋白可直接进入细胞内 .这一结果为用外源蛋白负载(L oading)免疫细胞提供了新的途径 .1 材料和方法1.1  DNA重组 人工合…  相似文献   
48.
A modern malaise   总被引:1,自引:0,他引:1  
JS Robertson Dr   《Public health》1999,113(4):155-156
  相似文献   
49.
50.
The prevalence of microalbuminuria was assessed in 50 patients of non-insulin dependent diabetes mellitus. The mean age of patients was 52.1 ± 11.6 years and the duration of diabetes was 8.3 ± 6.8 years. Twenty (40%) patients had microalbuminuria. Microalbuminuria was more common in patients with a longer duration of diabetes (more than 5 years), a poor glycaemic control, and higher systolic blood pressure.KEY WORDS: Microalbuminuria, Diabetes mellitus, Diabetic nephropathy, Chronic renal failure  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