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   1454篇
  免费   93篇
  国内免费   47篇
耳鼻咽喉   15篇
儿科学   27篇
妇产科学   33篇
基础医学   142篇
口腔科学   28篇
临床医学   219篇
内科学   408篇
皮肤病学   18篇
神经病学   66篇
特种医学   74篇
外科学   243篇
综合类   32篇
预防医学   79篇
眼科学   18篇
药学   119篇
中国医学   6篇
肿瘤学   67篇
  2023年   9篇
  2022年   12篇
  2021年   18篇
  2020年   13篇
  2019年   26篇
  2018年   21篇
  2017年   13篇
  2016年   28篇
  2015年   29篇
  2014年   34篇
  2013年   35篇
  2012年   63篇
  2011年   72篇
  2010年   48篇
  2009年   40篇
  2008年   75篇
  2007年   98篇
  2006年   92篇
  2005年   69篇
  2004年   65篇
  2003年   62篇
  2002年   59篇
  2001年   49篇
  2000年   56篇
  1999年   41篇
  1998年   22篇
  1997年   24篇
  1996年   23篇
  1995年   16篇
  1994年   14篇
  1993年   11篇
  1992年   34篇
  1991年   22篇
  1990年   30篇
  1989年   36篇
  1988年   25篇
  1987年   22篇
  1986年   22篇
  1985年   17篇
  1984年   18篇
  1983年   13篇
  1982年   12篇
  1979年   7篇
  1978年   6篇
  1977年   7篇
  1976年   7篇
  1975年   6篇
  1974年   6篇
  1973年   12篇
  1969年   6篇
排序方式: 共有1594条查询结果,搜索用时 15 毫秒
1.
2.
异落新妇甙的结构研究   总被引:1,自引:0,他引:1  
李伊庆  易杨华  汤海峰  肖凯 《药学学报》1996,31(10):761-763
从百合科菝葵属植物土茯苓(Smilaxg labra Roxb.)根茎的乙醇提取物中分得一个新的天然化合物(I),命名为异落新妇甙(isoastilbin)。根据元素分析,UV,IR,1H-NMR,13C-NMR,2DNMR及FAB-MS,确定化合物I的结构为5,7,3',5'-四羟基二氢黄酮醇-3-O-α-L-鼠李糖甙。  相似文献   
3.
4.
The language-reading relationship in normal and reading-disabled children   总被引:1,自引:0,他引:1  
In this study, the word retrieval, phonological awareness, sentence completion, and narrative discourse processing skills of 93 reading-disabled and 93 normally achieving subjects from 8 to 14 years of age were compared. The subjects were matched for age, sex, and neighborhood. Results revealed that the two groups differed significantly on the time and accuracy of word retrieval, their ability to produce a syntactically appropriate structure in a sentence completion task, their retelling of stories that had been read to them, their answers to questions about the stories, and their inferences. Further analysis revealed that the variance in the younger reading-disabled children's reading comprehension scores was best accounted for by their performance on the sentence completion and word retrieval measures; the inferencing skills of the older reading-disabled children best accounted for the variance in their reading comprehension. By contrast, the younger normally achieving children's reading comprehension scores were best accounted for by their sentence completion, the proportion of the stories that they retold, and word retrieval scores. The proportion of stories retold and the phonological awareness score of the older normally achieving children best accounted for the variance in their reading scores. These findings suggest that the oral language skills of normally achieving and reading-disabled children may relate differently to their reading comprehension at different age levels.  相似文献   
5.
6.
Oral glucocorticoids are widely used to treat exacerbations of asthma and COPD. A role for their use in treating exacerbations in Cystic Fibrosis (CF) is not proven. We describe the current practice, amongst UK adult CF physicians, of oral glucocorticoid use as an adjuvant to intravenous (IV) antibiotic treatment during CF pulmonary exacerbation (P EX). The survey also examined whether physicians thought a randomised controlled trial (RCT) was necessary and their willingness to participate patients in such a trial. Eighty one percent of physicians replied. All of them used corticosteroids with P EX. Most physicians supported the need for a RCT and would be willing to enroll consenting patients in the trial. This survey highlighted the need for a RCT which would examine the role of adjuvant corticosteroids to IV antibiotics in CF P EX.  相似文献   
7.
OBJECTIVE: The indications for pre-operative radiotherapy in rectal cancer are still unclear with the exception of T4 tumours. The aim of this study was to assess local and overall recurrence in patients with T1-T3 rectal cancers undergoing total mesorectal excision (TME). METHODS: Prospective data was collected from 150 patients with rectal cancer treated in one surgical centre between July 1997 and July 2002. One hundred and twenty-nine primary resections were carried of which 102 were with curative intent. Seventy-nine patients with T1-T3 tumours were included in the analysis. Nine had local resections and 70 underwent TME; 19 of the 70 patients were node positive and 51 were node negative. RESULTS: At a median follow-up of 37 months (range 19-79 months) there were 3 (4.3%) isolated local recurrences. One node positive patient developed isolated local recurrence compared with 2 node negative patients. The node positive patient died from a myocardial infarction while the two node negative patients died as a consequence of local recurrence. Three (4.3%) of 70 patients developed systemic relapse all of whom were node positive. The cancer specific mortality rate over the same follow-up period was 3/19 for node positive patients and 2/51 for node negative patients. Of 9 patients who had local resections, none developed local recurrence or systemic relapse. CONCLUSIONS: With TME the rate of local recurrence in T1-T3 tumours is low. Our results do not support the use of pre-operative radiotherapy for these patients.  相似文献   
8.
9.
一些保肝药物对原代培养大鼠肝细胞糖原合成功能的影响   总被引:1,自引:0,他引:1  
王惠芬  丛铮 《药学学报》1989,24(9):653-658
本文参照PO Seglen的方法并加以修改,建立了原代培养大鼠肝细胞糖原合成功能的测定体系。观察到联苯双酯既能使正常肝细胞合成糖原增加88%,又能保护肝细胞完全拮抗四氯化碳对其功能的损伤;银耳多糖能使四氯化碳对肝细胞糖原合成功能的损伤减轻57%;去甲斑蝥素10μg/ml能增加肝细胞糖原合成,浓度增加到100μg/ml时,此作用减弱,1000μg/ml则明显抑制糖原的合成,而且在10~100μg/ml浓度时,即能加强四氯化碳的损伤作用;100μg/ml CL1500和熊果酸二钠单独应用可增加肝细胞糖原合成,但与四氯化碳同时应用,反而加重对糖原合成的抑制作用。  相似文献   
10.
Vascularization is a prominent event during corpus luteum formation, providing low density lipoproteins for steroid biosynthesis and enabling transport of secreted steroids. The process of vascularization is controlled by specific regulators. Vascular endothelial growth factor (VEGF), otherwise named vascular permeability factor (VPF), induces endothelial cell proliferation as well as angiogenesis in vivo and increases capillary permeability. Here we report the expression of VEGF/VPF mRNA by cultured human luteinized granulosa cells (GC) for at least 10 days. Without HCG VEGF/VPF expression declined after day 4 and by day 10 was reduced to approximately 30% of the value at day 4. However, after culture in the presence of 1 U/ml human chorionic gonadotrophin (HCG), expression of VEGF/VPF mRNA by GC was four times greater than control experiments by day 10, and increased 100% from day 4 to day 10. Simultaneously, HCG supplementation increased VEGF/VPF secretion by GC. Medium VEGF/VPF on day 3 was 13 pM without and 11 pM with HCG. Medium VEGF/VPF on day 10 was 6 pM without HCG and 29 pM with HCG. These results suggest that vascularization of the corpus luteum is induced by HCG-mediated effects of VEGF/VPF.   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