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   1650篇
  免费   141篇
  国内免费   49篇
耳鼻咽喉   8篇
儿科学   44篇
妇产科学   13篇
基础医学   213篇
口腔科学   31篇
临床医学   237篇
内科学   358篇
皮肤病学   53篇
神经病学   123篇
特种医学   218篇
外科学   177篇
综合类   20篇
预防医学   124篇
眼科学   27篇
药学   123篇
中国医学   3篇
肿瘤学   68篇
  2023年   11篇
  2022年   44篇
  2021年   72篇
  2020年   41篇
  2019年   48篇
  2018年   42篇
  2017年   29篇
  2016年   42篇
  2015年   48篇
  2014年   64篇
  2013年   69篇
  2012年   95篇
  2011年   104篇
  2010年   47篇
  2009年   56篇
  2008年   69篇
  2007年   108篇
  2006年   65篇
  2005年   78篇
  2004年   57篇
  2003年   56篇
  2002年   42篇
  2001年   45篇
  2000年   39篇
  1999年   39篇
  1998年   35篇
  1997年   39篇
  1996年   33篇
  1995年   30篇
  1994年   30篇
  1993年   23篇
  1992年   27篇
  1991年   20篇
  1990年   16篇
  1989年   22篇
  1988年   23篇
  1987年   13篇
  1986年   18篇
  1985年   16篇
  1984年   5篇
  1983年   11篇
  1982年   7篇
  1981年   10篇
  1980年   10篇
  1979年   6篇
  1978年   7篇
  1977年   15篇
  1976年   9篇
  1975年   5篇
排序方式: 共有1840条查询结果,搜索用时 15 毫秒
1.
2.
3.
Percutaneous intervention in saphenous vein grafts (SVG) carries a higher risk of distal embolization than intervention in a native vessel, and use of a distal protection device has been shown to improve the outcomes in SVG interventions. We describe an intervention done in an unexpected 'Y' SVG which required dual distal protection with Filterwires placed in both limbs of the diseased graft and which was performed via a 6 Fr guide catheter.  相似文献   
4.
5.
Cerebellar hemorrhage is a devastating condition with morbidity and mortality related not only to the etiology of the hemorrhage, but also to the timing of the intervention. Sixteen consecutive pediatric patients with acute cerebellar hemorrhages are presented: 6 had vascular abnormalities, 3 had tumors, and 2 had hemorrhages of unknown etiology. Thirteen of the 16 patients survived with only 1 of the 13 having persistent vegetative state as a neurologic outcome. Six of 8 patients presenting in a moribund condition had good outcomes, and 3 of 4 patients presenting with fixed and dilated pupils also had good outcomes. Thus, in contrast to adults, rapid evaluation by CT scanning, followed by the judicious use of ventricular drainage and prompt surgical treatment, have resulted in favorable outcomes in pediatric patients despite their poor clinical presentations. None of the neonates having cerebellar hemorrhages required surgical intervention; their courses could be followed clinically and with transfontanel ultrasound.Presented as a poster at the 14th Congress of the European Society for Paediatric Neurosurgery, Lyon, France, 21–23 September 1994, and the XXII Annual Meeting of the International Society for Pediatric Neurosurgery, Birmingham, UK, 25–28 September 1994  相似文献   
6.
7.
8.
Results of clinical, contrast enema (CE), and computed tomographic (CT) examinations in 39 patients with perforated colorectal neoplasms were retrospectively reviewed. Twenty patients were toxemic at initial presentation, but in only four patients was the diagnosis of perforated colorectal neoplasm initially suspected clinically. CE study was performed in 22 patients and enabled the diagnosis of perforated neoplasm in 11 cases, neoplasm alone in eight, and neither neoplasm nor perforation in three. CT was performed in 38 patients and enabled the diagnosis of perforated neoplasm in 36; pericolic phlegmon but no mass lesion was evident in two. In 16 patients, CT also demonstrated metastatic disease. Because of its reliability in establishing the diagnosis and staging the extent of the inflammatory and neoplastic disease, CT is indicated in cases of suspected or proved perforated colorectal neoplasm and in cases in which CE study findings are indeterminate or suggestive of perforated neoplasm.  相似文献   
9.
报道了氯仿重结晶的棉酚的化学性质,样品在不同温度下干燥恒重后,经熔点、薄层层析、紫外光谱、红外光谱、X-射线衍射、热重量分析、元素(C,H,Cl)分析及棉酚合量测定等一系列的分析,确证了在60℃以下棉酚与氯仿成溶剂化物(solvate)。随着干燥温度的升高或在室温长时间的贮存,此现象逐渐消失,100℃真空干燥恒重后成为纯棉酚。  相似文献   
10.
The species diversity and genetic structure of mosquitoes belonging to the Anopheles maculatus group in Southeast Asia were investigated using the internal transcribed spacer 2 (ITS2) of ribosomal DNA (rDNA). A molecular phylogeny indicates the presence of at least one hitherto unrecognised species. Mosquitoes of chromosomal form K from eastern Thailand have a unique ITS2 sequence that is 3.7% divergent from the next most closely related taxon (An. sawadwongporni) in the group. In the context of negligible intraspecific variation at ITS2, this suggests that chromosomal form K is most probably a distinct species. Although An. maculatus sensu stricto from northern Thailand and southern Thailand/peninsular Malaysia differ from each other in chromosomal banding pattern and vectorial capacity, no intraspecific variation was observed in the ITS2 sequences of this species over this entire geographic area despite an extensive survey. A PCR-based identification method was developed to distinguish five species of the group (An. maculatus, An. dravidicus, An. pseudowillmori, An. sawadwongporni and chromosomal form K) to assist field-based studies in northwestern Thailand. Sequences from 187 mosquitoes (mostly An. maculatus and An. sawadwongporni) revealed no intraspecific variation in specimens from Thailand, Cambodia, mainland China, Malaysia, Taiwan and Vietnam, suggesting that this identification method will be widely applicable in Southeast Asia. The lack of detectable genetic structure also suggests that populations of these species are either connected by gene flow and/or share a recent common history.  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