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   5358篇
  免费   419篇
  国内免费   24篇
耳鼻咽喉   40篇
儿科学   240篇
妇产科学   125篇
基础医学   622篇
口腔科学   60篇
临床医学   1044篇
内科学   927篇
皮肤病学   115篇
神经病学   350篇
特种医学   165篇
外科学   513篇
综合类   182篇
一般理论   4篇
预防医学   710篇
眼科学   50篇
药学   339篇
中国医学   1篇
肿瘤学   314篇
  2023年   21篇
  2022年   37篇
  2021年   99篇
  2020年   69篇
  2019年   112篇
  2018年   114篇
  2017年   106篇
  2016年   107篇
  2015年   118篇
  2014年   155篇
  2013年   295篇
  2012年   414篇
  2011年   387篇
  2010年   231篇
  2009年   189篇
  2008年   381篇
  2007年   380篇
  2006年   377篇
  2005年   396篇
  2004年   375篇
  2003年   347篇
  2002年   356篇
  2001年   39篇
  2000年   37篇
  1999年   48篇
  1998年   70篇
  1997年   47篇
  1996年   43篇
  1995年   45篇
  1994年   28篇
  1993年   25篇
  1992年   25篇
  1991年   21篇
  1990年   25篇
  1989年   25篇
  1988年   19篇
  1987年   19篇
  1986年   12篇
  1985年   14篇
  1984年   19篇
  1983年   26篇
  1982年   18篇
  1981年   20篇
  1980年   9篇
  1979年   10篇
  1978年   9篇
  1975年   8篇
  1973年   11篇
  1972年   10篇
  1971年   8篇
排序方式: 共有5801条查询结果,搜索用时 15 毫秒
1.
2.

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   
3.
4.
5.
The digestive properties of Australian elapid snake venoms have not been studied to any great extent. To address this, the in vitro digestive properties of Oxyuranus scutellatus (Australian Coastal Taipan) venom were investigated in a simulation of the in vivo conditions using the parameters reported for the stomach of snakes and representative prey for this species. The amount of soluble protein released was measured over time using a bicinchoninic acid (BCA) assay. Dismembered mouse hindlegs were injected intramuscularly with 0.1 ml O. scutellatus venom (concentration 10 mg/ml) and maintained in a micro-anaerobic, acidic environment (pH approximately 1.2-1.7) at 25 degrees C. The bathing liquid was sampled every 24 h for 7 days, and assayed for soluble protein. Statistical analysis revealed that O. scutellatus venom increased the rate at which proteins were released when compared to a negative control suggesting the potential importance of envenomation in the digestion of whole prey.  相似文献   
6.
7.
8.
Diabetic neuropathic foot ulcers and amputation   总被引:2,自引:0,他引:2  
A neuropathic foot ulcer is a severe complication of diabetes that can result in a more severe complication, a lower extremity amputation. We conducted a cohort study of 24,616 individuals with a diabetic neuropathic foot ulcer treated within a multicenter wound care network. A total of 1653 (6.7%) individuals had an amputation and 46.3% of these amputations were of a toe or ray (minor amputation). In the more than 10-year follow-up period that we studied, the percentage of those who had an amputation varied between 5.6% and 8.4%. Of those who had an amputation, the percentage that had a minor amputation increased over time from 4.0% in the earliest years to more than 60% in the later years of observation. The single most important determinant of amputation was the observation of fascia, tendon, and bone at the initial assessment. In conclusion, about 7% of those with a diabetic neuropathic foot ulcer will have an amputation and in the past 10 years there has been a remarkable increase in the number of minor as compared to major amputations.  相似文献   
9.
10.
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