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   3705篇
  免费   471篇
  国内免费   12篇
耳鼻咽喉   17篇
儿科学   96篇
妇产科学   314篇
基础医学   349篇
口腔科学   113篇
临床医学   1072篇
内科学   691篇
皮肤病学   73篇
神经病学   142篇
特种医学   305篇
外科学   225篇
综合类   86篇
一般理论   1篇
预防医学   229篇
眼科学   32篇
药学   235篇
肿瘤学   208篇
  2023年   47篇
  2021年   31篇
  2020年   55篇
  2019年   49篇
  2018年   95篇
  2017年   105篇
  2016年   102篇
  2015年   122篇
  2014年   149篇
  2013年   163篇
  2012年   128篇
  2011年   139篇
  2010年   148篇
  2009年   145篇
  2008年   117篇
  2007年   124篇
  2006年   132篇
  2005年   98篇
  2004年   88篇
  2003年   112篇
  2002年   96篇
  2001年   110篇
  2000年   83篇
  1999年   102篇
  1998年   119篇
  1997年   136篇
  1996年   128篇
  1995年   110篇
  1994年   77篇
  1993年   56篇
  1992年   72篇
  1991年   59篇
  1990年   51篇
  1989年   80篇
  1988年   65篇
  1987年   65篇
  1986年   92篇
  1985年   75篇
  1984年   44篇
  1983年   41篇
  1982年   36篇
  1981年   34篇
  1980年   33篇
  1979年   34篇
  1978年   24篇
  1977年   27篇
  1976年   22篇
  1975年   25篇
  1974年   20篇
  1973年   22篇
排序方式: 共有4188条查询结果,搜索用时 31 毫秒
1.
2.
BACKGROUND: Computer-assisted image analysis has been proposed for human hair growth studies. METHODS: The performances of Trichoscan, a commercially available automated system combining epiluminiscence microscopy with digital image analysis, developed for office-based hair growth measurements, have been evaluated comparatively on the same skin sites using standardized photographic equipment and calibrated processing for contrast-enhanced phototrichogram (CE-PTG) analysis. This reference method has been validated with scalp biopsies and histological examination of serial sectioning. RESULTS: Besides edge effects, hair fibres escaped the Trichoscan analysis for various reasons including, but not limited to, thickness, pigmentation, closeness and crossing. CONCLUSION: Most of these problems have been identified in the late 1980s and remain largely unsolved by the processing software that was evaluated in 2004. Therefore claims promoting the Trichoscan method for accurate hair measurements in clinical trials on scalp and body hair are not supported by the present investigation. The speed at which the analysis is performed is outweighed by the errors in signal detection. Therefore we suggest that improvements must be clearly documented before Trichoscan is established for quantified diagnostic purposes and detailed hair cycle monitoring during hair trials.  相似文献   
3.
双波长紫外分光光度法测定贝母中腺苷和胸苷的含量   总被引:4,自引:0,他引:4  
将4种贝母的甲醇提取物经薄层色谱法粗分离后,直接用双波长紫外分光光度法测定其含量。结果表明,该方法线性关系好,腺苷和胸苷标准曲线的相关系数均为0.9999,同时也发现平贝、炉贝和伊贝中腺苷都占核苷总量60%以上,而浙贝中仅占约40%,提示贝母生药的抗凝血活性可能与贝母中核苷类化合物的种类和含量的差别有关。  相似文献   
4.
5.
6.
The purpose of this study was to evaluate the use of serum fibronectin and serum somatomedin-C as nutritional markers during enteral nutrition support (ENS) of critically ill, traumatized patients using an enteral product containing high concentrations of branched-chain amino acids. Twelve critically injured patients received a standard enteral formula with 30 g of a 44% branched-chain amino acid supplement added to each liter of formula. Fibronectin concentration, somatomedin-C concentration, and nitrogen balance were measured on study days 1, 4, 7, 14, 21, 28 or until adequate oral intake began. Both fibronectin and somatomedin-C concentrations increased significantly from baseline by day 7 of ENS. Nitrogen balance increased significantly from baseline by day 4. On days 14 and 21, only somatomedin-C and nitrogen balance increased significantly from baseline. Nitrogen balance was significantly correlated with somatomedin-C concentration (r = 0.53, p less than 0.01), cumulative caloric intake (r = 0.68, p less than 0.01), and cumulative nitrogen intake (r = 0.72, p less than 0.01). The results of this study suggest that serum somatomedin-C is useful and serum fibronectin has potential in monitoring nutrition support response in critically ill, traumatized patients.  相似文献   
7.
BACKGROUND: Based on good results in the treatment of superficial skin tumours, since the early 1990s topical photodynamic therapy with aminolaevulinic acid (ALA PDT) has been used for disseminated, inflammatory dermatoses including psoriasis. However, there is still a lack of well-documented trials. OBJECTIVE: A prospective randomized, double-blind phase I/II intrapatient comparison study was conducted in 12 patients to investigate whether topical ALA PDT is an effective treatment for chronic plaque-type psoriasis. METHODS: In each patient three psoriatic plaques were randomly treated with a light dose of 20 J/cm(2) and 0.1%, 1% and 5% ALA, respectively. Treatment was conducted twice a week until complete clearance or for a maximum of 12 irradiations. Therapeutic efficacy was assessed by weekly determination of the psoriasis severity index (PSI). RESULTS: The mean percentage improvement was 37.5%, 45.6% and 51.2% in the 0.1%, 1% and 5% ALA-treated groups, respectively. Irradiation had to be interrupted several times because of severe burning and pain sensation. CONCLUSION: Topical ALA PDT did not prove to be an appropriate treatment option for plaque-type psoriasis due to disappointing clinical efficacy, the time-consuming treatment procedure and its unfavourable adverse event profile.  相似文献   
8.
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