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   40373篇
  免费   2525篇
  国内免费   115篇
耳鼻咽喉   377篇
儿科学   1300篇
妇产科学   1155篇
基础医学   5386篇
口腔科学   726篇
临床医学   6198篇
内科学   7594篇
皮肤病学   762篇
神经病学   3756篇
特种医学   718篇
外科学   3887篇
综合类   430篇
一般理论   55篇
预防医学   4901篇
眼科学   551篇
药学   2403篇
中国医学   88篇
肿瘤学   2726篇
  2023年   225篇
  2022年   440篇
  2021年   898篇
  2020年   534篇
  2019年   909篇
  2018年   1052篇
  2017年   725篇
  2016年   727篇
  2015年   933篇
  2014年   1314篇
  2013年   1929篇
  2012年   2927篇
  2011年   3053篇
  2010年   1714篇
  2009年   1435篇
  2008年   2777篇
  2007年   2757篇
  2006年   2754篇
  2005年   2589篇
  2004年   2510篇
  2003年   2372篇
  2002年   2209篇
  2001年   354篇
  2000年   293篇
  1999年   402篇
  1998年   446篇
  1997年   396篇
  1996年   368篇
  1995年   307篇
  1994年   284篇
  1993年   264篇
  1992年   233篇
  1991年   207篇
  1990年   185篇
  1989年   155篇
  1988年   147篇
  1987年   153篇
  1986年   122篇
  1985年   126篇
  1984年   168篇
  1983年   173篇
  1982年   198篇
  1981年   169篇
  1980年   166篇
  1979年   108篇
  1978年   78篇
  1977年   88篇
  1976年   65篇
  1974年   84篇
  1973年   67篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
21.
22.
23.
24.
Dietary supplementation with vitamin K(1), with vitamin D(3) and calcium or their combination, was examined in healthy older women during a 2-year, double-blind, placebo-controlled trial. Combined vitamin K with vitamin D plus calcium was associated with a modest but significant increase in BMC at the ultradistal radius but not at other sites in the hip or radius. INTRODUCTION: The putative beneficial role of high dietary vitamin K(1) (phylloquinone) on BMD and the possibility of interactive benefits with vitamin D were studied in a 2-year double-blind, placebo-controlled trial in healthy Scottish women > or =60 years of age. MATERIALS AND METHODS: Healthy, nonosteoporotic women (n = 244) were randomized to receive either (1) placebo, (2) 200 microg/day vitamin K(1), (3) 10 microg (400 IU) vitamin D(3) plus 1000 mg calcium/day, or (4) combined vitamins K(1) and D(3) plus calcium. Baseline and 6-month measurements included DXA bone mineral scans of the hip and wrist, markers of bone turnover, and vitamin status. Supplementation effects were tested using multivariate general linear modeling, with full adjustment for baseline and potential confounding variables. RESULTS: Significant bone mineral loss was seen only at the mid-distal radius but with no significant difference between groups. However, women who took combined vitamin K and vitamin D plus calcium showed a significant and sustained increase in both BMD and BMC at the site of the ultradistal radius. Serum status indicators responded significantly to respective supplementation with vitamins K and D. Over 2 years, serum vitamin K(1) increased by 157% (p < 0.001), the percentage of undercarboxylated osteocalcin (%GluOC) decreased by 51% (p < 0.001), serum 25-hydroxyvitamin D [25(OH)D] increased by 17% (p < 0.001), and PTH decreased by 11% (p = 0.049). CONCLUSIONS: These results provide evidence of a modest synergy in healthy older women from nutritionally relevant intakes of vitamin K(1) together with supplements of calcium plus moderate vitamin D(3) to enhance BMC at the ultradistal radius, a site consisting of principally trabecular bone. The substantial increase in gamma-carboxylation of osteocalcin by vitamin K may have long-term benefits and is potentially achievable by increased dietary intakes of vitamin K rather than by supplementation.  相似文献   
25.
Fear of falling, defined as a lack of self-confidence that one may avoid falls while doing everyday activities, may have serious consequences for elderly people. This article examines the prevalence, risk factors, and consequences of fear of falling in the elderly population; methods for assessing those fears; and suggests evidence-based interventions. Incorporating successful strategies into programs to reduce falling can result in improved patient outcomes as well as decreased healthcare utilization and costs.  相似文献   
26.
OBJECTIVES: To determine if experienced clinical educators (CEs) can improve their teaching by incorporating 4 literature-based teaching methods into their instruction. METHODS: We trained 7 experienced CEs on the teaching methods during a monthly faculty development program. Each CE recorded use of these methods during 10 months on a personal digital assistant. We compared the CEs' teaching evaluations with those of nonparticipating faculty by analysis of variance at baseline, during the study period, and for 1 year after the study. RESULTS: Reported use of 2 teaching methods (priming and feedback) increased significantly over use at baseline; use of 2 other methods (teaching in the patient's presence and 1-2 focal teaching points) remained constant. Scores on the CEs' teaching evaluations were significantly higher during the study period on 1 item, whereas the comparison group showed no changes. The changes persisted during the follow-up period. CEs reported that the teaching methods focused the learner and teacher, making subsequent encounters more productive. They also found that the act of entering data daily prompted them to reflect on their teaching. CONCLUSIONS: Experienced teachers can be persuaded to incorporate new methods into their daily teaching. Reflection on teaching is enhanced with group support and daily reminders. With these interventions, teaching effectiveness of these experienced educators improved.  相似文献   
27.
28.
29.
A high-performance liquid chromatographic method is developed for the determination of bulk sertaconazole nitrate and related compounds (potential impurities and degradation products) as well as a sertaconazole nitrate cream formulation. A 10-microns Spherisorb CN column is used along with a mobile phase consisting of acetonitrile and aqueous 0.01 M sodium phosphate (37:63, v/v). The sertaconazole nitrate peak is monitored at a wavelength of 260 nm; the retention time being 19.3 min. The detector response for sertaconazole nitrate is linear over the concentration range from 64 to 96 micrograms ml-1. The method is found to be sufficiently selective for the reliable determination of related compounds, FI-7001, FI-7009 and FI-7011, as indicated by same-day and between-day relative standard deviations (RSD) for replicate assays of 1.72% (n = 9) and 2.17% (n = 24), respectively. The application of this method to a cream formulation of sertaconazole nitrate is found to give a mean percentage recovery of 99.4% with RSD of 1.14% (n = 9); none of the cream vehicle peaks are found to interfere with the determination of sertaconazole nitrate.  相似文献   
30.
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