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   2164篇
  免费   317篇
  国内免费   8篇
耳鼻咽喉   3篇
儿科学   66篇
妇产科学   289篇
基础医学   113篇
口腔科学   27篇
临床医学   879篇
内科学   264篇
皮肤病学   52篇
神经病学   183篇
特种医学   238篇
外科学   57篇
综合类   61篇
预防医学   150篇
眼科学   5篇
药学   49篇
肿瘤学   53篇
  2023年   43篇
  2021年   8篇
  2020年   35篇
  2019年   20篇
  2018年   60篇
  2017年   93篇
  2016年   76篇
  2015年   99篇
  2014年   113篇
  2013年   113篇
  2012年   60篇
  2011年   74篇
  2010年   117篇
  2009年   107篇
  2008年   56篇
  2007年   56篇
  2006年   64篇
  2005年   50篇
  2004年   38篇
  2003年   62篇
  2002年   46篇
  2001年   54篇
  2000年   26篇
  1999年   63篇
  1998年   95篇
  1997年   109篇
  1996年   107篇
  1995年   94篇
  1994年   65篇
  1993年   53篇
  1992年   38篇
  1991年   29篇
  1990年   16篇
  1989年   38篇
  1988年   42篇
  1987年   30篇
  1986年   31篇
  1985年   33篇
  1984年   18篇
  1983年   16篇
  1982年   23篇
  1981年   13篇
  1980年   15篇
  1979年   8篇
  1978年   17篇
  1977年   17篇
  1976年   19篇
  1975年   15篇
  1974年   4篇
  1973年   3篇
排序方式: 共有2489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.
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   
5.
6.
OBJECTIVE: The purpose of this study is to examine the incidence and clinical predictors of symptom deterioration in depressed elderly patients who have responded to treatment in primary care. METHOD: A cohort study of 901 older adults from 18 primary care clinics in five states who met Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) criteria for major depression and/or dysthymia at baseline interview, had participated in a trial of collaborative care for depression compared to usual care, and had improved to the point of no longer meeting criteria for major depression at 12 months were observed for one year (18 and 24 months) after enrolling in the original study. RESULTS: A total of 40% of patients met criteria for significant depressive symptom deterioration over the 12- to 24-month observational period. Among usual-care patients, higher initial severity of depression and a higher number of residual DSM-IV depressive symptoms at 12 months were significant predictors of symptom deterioration. No variables predicted symptom deterioration in intervention patients. CONCLUSIONS: There is a high rate of symptom deterioration among elderly patients in primary care who are treated for depression. Efforts to improve long-term outcomes of older patients with major depression and/or dysthymia should focus on providing more intensive treatment and follow up for patients with residual depressive symptoms.  相似文献   
7.
8.
9.
AIM: The aim of this study was to investigate the nature and organization of maternal needs and priorities in a neonatal unit. BACKGROUND: The relationship between maternal needs and priorities appears to be an under studied area in neonatal nursing. METHODS: A quantitative survey was carried out based on 209 mothers with premature infants. Two self-assessment schedules were used: critical care maternal needs inventory (J. Leske, Heart and Lung 15, 27-42) and a ranking scale. The data were analysed with multivariate analysis. FINDINGS: Data analysis revealed clear priorities in maternal needs. In particular the need for accurate infant related information was a priority for 93% of the mothers. Good communication practices with professionals were also valued. The mothers displayed altruistic behaviour, and self-related needs took second place. It is proposed that maternal needs demonstrate a hierarchical organization. CONCLUSION: It is important for nurses to consider the individual needs of the mothers, simply because the satisfaction of these needs is essential for maternal well-being.  相似文献   
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