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   908篇
  免费   98篇
  国内免费   6篇
儿科学   42篇
妇产科学   35篇
基础医学   131篇
口腔科学   11篇
临床医学   101篇
内科学   248篇
皮肤病学   24篇
神经病学   20篇
特种医学   112篇
外科学   85篇
综合类   12篇
预防医学   66篇
眼科学   7篇
药学   85篇
肿瘤学   33篇
  2022年   6篇
  2021年   8篇
  2020年   10篇
  2019年   16篇
  2018年   20篇
  2017年   16篇
  2016年   19篇
  2015年   17篇
  2014年   22篇
  2013年   35篇
  2012年   24篇
  2011年   23篇
  2010年   27篇
  2009年   33篇
  2008年   33篇
  2007年   29篇
  2006年   33篇
  2005年   37篇
  2004年   26篇
  2003年   28篇
  2002年   38篇
  2001年   24篇
  2000年   23篇
  1999年   28篇
  1998年   34篇
  1997年   33篇
  1996年   36篇
  1995年   25篇
  1994年   30篇
  1993年   24篇
  1992年   20篇
  1991年   15篇
  1990年   20篇
  1989年   18篇
  1988年   18篇
  1987年   19篇
  1986年   17篇
  1985年   13篇
  1984年   12篇
  1983年   8篇
  1982年   8篇
  1981年   12篇
  1980年   10篇
  1978年   4篇
  1977年   8篇
  1976年   14篇
  1975年   5篇
  1971年   4篇
  1970年   6篇
  1967年   3篇
排序方式: 共有1012条查询结果,搜索用时 625 毫秒
1.

Background

The purpose of the study was to evaluate the association between fetal echocardiographic measurements and the need for intervention (primary coarctation repair, staged coarctation repair, or catheter intervention) in prenatally diagnosed coarctation of the aorta.

Methods

A single-centre retrospective cohort study (2005-2015) of 107 fetuses diagnosed with suspected coarctation of the aorta in the setting of an apex-forming left ventricle and antegrade flow across the mitral and aortic valves.

Results

Median gestational age at diagnosis was 32 weeks (interquartile range, 23-35 weeks). Fifty-six (52%) did not require any neonatal intervention, 51 patients (48%) underwent a biventricular repair. In univariable analysis, an increase in ascending aorta (AAo) peak Doppler flow velocity (odds ratio [OR], 1.40 [95% confidence interval [CI], 1.05-1.91] per 20 cm/s; P = 0.03) was associated with intervention. No intervention was associated with larger isthmus size (OR, 0.23; P < 0.001), transverse arch diameter (OR, 0.23; P < 0.001), and aortic (OR, 0.72; P = 0.02), mitral (OR, 0.58; P = 0.001), and AAo (OR, 0.53; P < 0.001) z-scores. In multivariable analysis, higher peak AAo Doppler (OR, 2.51 [95% CI, 1.54-4.58] per 20 cm/s; P = 0.001) and younger gestational age at diagnosis (OR, 0.81 [95% CI, 0.70-0.93] per week; P = 0.005) were associated with intervention, whereas a higher AAo z-score (OR, 0.65 [95% CI, 0.43-0.94] per z; P = 0.029) and transverse arch dimension (OR, 0.44 [95% CI, 0.18-0.97]; P = 0.05) decreased the risk of intervention.

Conclusions

In prenatally suspected coarctation, the variables associated with intervention comprised smaller AAo and transverse arch size, earlier gestational age at diagnosis, and the additional finding of a higher peak AAo Doppler.  相似文献   
2.
Introduction: There are at the minimum two major, quite different approaches to advance drug discovery. The first being the target-based drug discovery (TBDD) approach that is commonly referred to as the molecular approach. The second approach is the phenotype-based drug discovery (PBDD), also known as physiology-based drug discovery or empirical approach.

Area covered: The authors discuss, herein, the need for developing radiation countermeasure agents for various sub-syndromes of acute radiation syndromes (ARS) following TBDD and PBDD approaches. With time and continuous advances in radiation countermeasure drug development research, the expectation is to have multiple radiation countermeasure agents for each sub-syndrome made available to radiation exposed victims.

Expert opinion: The majority of the countermeasures currently being developed for ARS employ the PBDD approach, while the TBDD approach is clearly under-utilized. In the future, an improved drug development strategy might be a ‘hybrid’ strategy that is more reliant on TBDD for the initial drug discovery via large-scale screening of potential candidate agents, while utilizing PBDD for secondary screening of those candidates, followed by tertiary analytics phase in order to pinpoint efficacious candidates that target the specific sub-syndromes of ARS.  相似文献   

3.
4.
5.
Anti-rheumatic therapy has been targeted against the symptoms arising from chronic inflammation of the joint. This has resulted in the extensive use of non-steroidal anti-inflammatory drugs. It is now becoming apparent that these agents have no beneficial effect on disease progression. This mini review concentrates on the formation and maintenance of pannus, the granulomatous tissue responsible for cartilage and bone erosion. This reveals a number of possible therapeutic targets. Protease inhibitors could be used to interfere with the degradatory processes. The diverse functions of endothelial cells suggest oedema formation, cell accumulation and supply of nutrients to the granulomatous tissue could all be targeted by appropriate therapy. Alternatively the immune processes that control pannus formation and state of activation could be regulated by interfering with antigen presentation and the cytokine network.  相似文献   
6.
7.
作者分别用差速离心法及蔗糖梯度离心法制备胎盘微绒毛膜(PMM),用受体放射分析法研究了PMM的转铁蛋白受体(TfB),结果表明:两种方法制备的PMM均可用于受体分析,但差速离心法更为简便。测定60例产妇PMM的TfR,其数目为3.53±1.98×10~(12)个位点/mg膜蛋白,最大结合容量为6.33±4.21×10~(-12)mol/mg膜蛋白,Kd值为4.95±3.39×10~(-9)mol/L。受体结合反应体系最适实验条件为,膜蛋白浓度每管50μg,标记物浓度每管50 000cpm,孵育30分钟,B/F分离的聚乙二醇浓度为12%(W/V)。对TfR的特性研究表明:TfR与转铁蛋白的结合具有高度亲和力、高度特异性及可饱和性。  相似文献   
8.
9.
10.
OBJECTIVES: The appearance of Grannum Grade III changes in the placenta at around 34-36 weeks is a predictor of adverse perinatal outcome, which may be reduced by reporting to the clinician. This has led to the suggestion that the placental grade should be noted during any third-trimester scan. There are no published data on the reproducibility of sonographic Grannum grading of the placenta; the objective of this study was to evaluate intra- and interobserver variation. METHODS: Fifty-five placental images from normal and complicated pregnancies of several different gestational ages were collected between April and October 2001. Three fetal medicine consultants and three experienced sonographers graded the images as 0, I, II, III or ungradeable. They then regraded the same images, presented in a different order and with different codes, 4-6 weeks later. Observers were blinded to their previous grading and to each others'. Weighted kappa (kappa), with linear weights, was used to look for strength of agreement. RESULTS: There was good agreement between the two observations of each placental image for five observers (kappa = 0.61 to 0.90), and moderate agreement for one observer (kappa = 0.56). However, the kappa-values for comparisons between the 15 pairs of observers ranged from 0.24 to 0.69 with six values below 0.41, indicating only fair agreement. This was confirmed by the overall kappa-value of 0.24 between all six observers. The agreement between the observers for Grade III placenta was poor, with an overall kappa-value of 0.09. CONCLUSIONS: Although intraobserver agreement was generally good, interobserver agreement was only fair for all grades and poor for Grade III placenta. This may be an indication that Grannum grading is not reproducible or it may reflect a need for training in those performing grading. Such variation may limit the effectiveness of reporting Grannum grades in clinical practice.  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