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   1786篇
  免费   87篇
  国内免费   11篇
耳鼻咽喉   19篇
儿科学   99篇
妇产科学   42篇
基础医学   198篇
口腔科学   67篇
临床医学   94篇
内科学   418篇
皮肤病学   56篇
神经病学   112篇
特种医学   183篇
外科学   183篇
综合类   17篇
预防医学   166篇
眼科学   22篇
药学   96篇
中国医学   3篇
肿瘤学   109篇
  2023年   7篇
  2022年   9篇
  2021年   36篇
  2020年   22篇
  2019年   36篇
  2018年   33篇
  2017年   43篇
  2016年   37篇
  2015年   31篇
  2014年   63篇
  2013年   81篇
  2012年   90篇
  2011年   94篇
  2010年   61篇
  2009年   72篇
  2008年   82篇
  2007年   77篇
  2006年   72篇
  2005年   75篇
  2004年   64篇
  2003年   65篇
  2002年   52篇
  2001年   41篇
  2000年   52篇
  1999年   54篇
  1998年   43篇
  1997年   41篇
  1996年   55篇
  1995年   35篇
  1994年   32篇
  1993年   41篇
  1992年   14篇
  1991年   27篇
  1990年   24篇
  1989年   24篇
  1988年   23篇
  1987年   31篇
  1986年   29篇
  1985年   18篇
  1984年   8篇
  1983年   4篇
  1982年   20篇
  1981年   7篇
  1980年   7篇
  1979年   5篇
  1977年   11篇
  1976年   10篇
  1975年   8篇
  1972年   2篇
  1971年   4篇
排序方式: 共有1884条查询结果,搜索用时 15 毫秒
31.
32.
We present a patient affected of diverticular disease of the colon, with diverticulosis and two giant diverticula of the sigma, both located at the mesenteric edge. We would like to stress the low incidence of reports about this entity in the medical literature, its uncommon location and the fact of a double lesion coinciding in a single patient. We discuss the most important nosocomial aspects and the different diagnoses. Finally, we support the idea of distinguishing three different entities that in the medical literature are usually unified as a single "giant diverticulum of the colon". We reaffirm ourselves on the importance of an early diagnosis and a correct indication for surgery.  相似文献   
33.
34.
35.
Higher fat and energy intakes confer a survival advantage in cystic fibrosis (CF). There is a need to develop effective nutrition programmes that ensure optimal energy intake in CF.

Methodology:


A cross-sectional measurement of clinical characteristics and energy and fat intakes in patients attending the CF outpatients clinic of the John Hunter Hospital, Newcastle was undertaken. Twenty-nine subjects, mean age 12 years (range 4.3–20.2), completed weighed food records to determine the contribution of fat to the percentage of the recommended energy intake obtained and to document use of pancreatic enzyme replacement therapy.

Results:


Diets with a high percentage of energy derived from fat did not guarantee that individuals with CF met their energy requirements. Subjects with total fat intakes of 100 g per day or greater, however, achieved in excess of 110% recommended daily intake (RDI) for energy. Up to 47% of subjects consumed more pancreatic enzyme replacement capsules than shown to give maximum effectiveness.

Conclusion:


Setting a 100 g daily fat target is a realistic way of ensuring high energy intakes in CF. Fat ready reckoners would identify the fat content of food and prescribe specific numbers of pancreatic enzyme replacement capsules to be consumed with each meal or food item.  相似文献   
36.
37.
38.
39.
Ravon  DM; Citarella  F; Lubbers  YT; Pascucci  B; Hack  CE 《Blood》1995,86(11):4134-4143
In a previous study we have shown that monoclonal antibody F1 (MoAb F1), directed against an epitope on the heavy chain of factor XII distinct from the binding site for anionic surfaces, is able to activate factor XII in plasma (Nuijens JH, et al: J Biol Chem 264; 12941, 1989). Here, we studied in detail the mechanism underlying the activation of factor XII by MoAb F1 using purified proteins. Formation of factor XIIa was assessed by measuring its amidolytic activity towards the chromogenic substrate H-D-Pro-Phe-Arg-pNA (S-2302) in the presence of soybean trypsin inhibitor and by assessing cleavage on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Upon incubation with MoAb F1 alone, factor XII was auto-activated in a time-dependent fashion, activation being maximal after 30 hours. Factor XII incubated in the absence of MoAb F1 was hardly activated by kallikrein, whereas in the presence of MoAb F1, but not in that of a control MoAb, the rate of factor XII activation by kallikrein was promoted at least 60-fold. Maximal activation of factor XII with kallikrein in the presence of MoAb F1 was reached within 1 hour. This effect of kallikrein on the cleavage of factor XII bound to MoAb F1 was specific because the fibrinolytic enzymes plasmin, urokinase, and tissue-type plasminogen activator could not substitute for kallikrein. Also, trypsin could easily activate factor XII, but in contrast to kallikrein, this activation was independent of MoAb F1. SDS-PAGE analysis showed that the appearance of amidolytic activity correlated well with cleavage of factor XII. MoAb F1-induced activation of factor XII in this purified system was not dependent on the presence of high- molecular-weight kininogen (HK), in contrast to the activation of the contact system in plasma by MoAb F1. Experiments with deletion mutants revealed that the epitopic region for MoAb F1 on factor XII is located on the kringle domain. Thus, this study shows that binding of ligands to the kringle domain, which does not contribute to the proposed binding site for negatively charged surfaces, may induce activation of factor XII. Therefore, these findings point to the existence of multiple mechanisms of activation of factor XII.  相似文献   
40.
Factors Influencing the Rate of Fibrosis Progression in Chronic Hepatitis C   总被引:3,自引:0,他引:3  
Alcohol consumption, age at infection, and male gender have been identified as risk factors for faster fibrosis progression in patients with chronic hepatitis C (CHC). Yet the influence of liver steatosis, light to moderate alcohol consumption, or iron overload on this progression remains controversial. To analyze the effect of individual risk factors and their interaction on fibrosis progression in a group of patients with CHC and a definite date of infection, we studied 133 consecutive untreated patients. Covariates included were age, body mass index (BMI), gender, age at infection, alcohol intake, serum lipids, glycemia, serum ALT, AST, GGT, iron, and ferritin, grade and stage (METAVIR and Scheuer), and hepatic stainable iron (Perl's stain). The rate of fibrosis progression was inferred from the METAVIR score. By logistic regression analysis, hepatic steatosis (odds ratio [OR], 3.035; 95% confidence interval [CI], 1.16-7.93), serum ferritin levels higher than 290 ng/ml (OR, 5.5; 1.6-18.65), and light to moderate ethanol intake (1-50 g/day) (OR, 5.22; 1.5-17.67) were independently associated with faster fibrosis progression. There was no effect of interaction between these variables on the rate of fibrosis progression. Liver steatosis, serum ferritin levels, and light to moderate alcohol intake are associated with faster fibrosis progression in chronic hepatitis C. Combination of these factors did not further accelerate this progression. The impact of modification of these factors on progression should be tested in longitudinal studies.  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