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   1288919篇
  免费   83566篇
  国内免费   2996篇
耳鼻咽喉   15505篇
儿科学   44514篇
妇产科学   33584篇
基础医学   179404篇
口腔科学   31483篇
临床医学   112959篇
内科学   247062篇
皮肤病学   25011篇
神经病学   106071篇
特种医学   51122篇
外国民族医学   305篇
外科学   197208篇
综合类   27824篇
一般理论   536篇
预防医学   105020篇
眼科学   28201篇
药学   89774篇
  4篇
中国医学   2826篇
肿瘤学   77068篇
  2019年   9337篇
  2018年   35373篇
  2017年   27941篇
  2016年   32276篇
  2015年   13870篇
  2014年   18707篇
  2013年   27801篇
  2012年   43432篇
  2011年   60393篇
  2010年   41663篇
  2009年   33477篇
  2008年   56803篇
  2007年   62408篇
  2006年   38794篇
  2005年   39796篇
  2004年   40173篇
  2003年   40152篇
  2002年   36651篇
  2001年   48396篇
  2000年   49404篇
  1999年   41369篇
  1998年   11978篇
  1997年   10803篇
  1996年   10412篇
  1995年   10731篇
  1994年   9999篇
  1993年   9280篇
  1992年   32957篇
  1991年   32199篇
  1990年   31669篇
  1989年   30457篇
  1988年   27728篇
  1987年   27899篇
  1986年   25921篇
  1985年   25176篇
  1984年   18965篇
  1983年   16016篇
  1982年   9991篇
  1981年   8889篇
  1979年   17269篇
  1978年   12554篇
  1977年   10620篇
  1976年   10019篇
  1975年   10387篇
  1974年   12585篇
  1973年   12082篇
  1972年   11041篇
  1971年   10233篇
  1970年   9516篇
  1969年   8888篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
ObjectiveTo determine prognostic factors and survival patterns for different treatment modalities for nasal cavity (NC) and paranasal sinus (PS) mucosal melanoma (MM).MethodsPatients from 1973 to 2013 were analyzed using the Surveillance, Epidemiology, and End Results (SEER) database. Kaplan-Meier method and multivariable cox proportional hazard modeling were used for survival analyses.ResultsOf 928 cases of mucosal melanoma (NC = 632, PS = 302), increasing age (Hazard Ratio [HR]:1.05/year, p < 0.001), T4 tumors (HR: 1.81, p = 0.02), N1 status (HR: 6.61, p < 0.001), and PS disease (HR: 1.50, p < 0.001) were associated with worse survival. Median survival length was lower for PS versus NC (16 versus 26 months, p < 0.001). Surgery and surgery + radiation therapy (RT) improved survival over non-treatment or RT alone (p < 0.001). Adding RT to surgery did not yield a survival difference compared with surgery alone (p = 0.43). Five-year survival rates for surgery and surgery + RT were similar, at 27.7% and 25.1% (p = 0.43).ConclusionSurgery increased survival significantly over RT alone. RT following surgical resection did not improve survival.  相似文献   
2.
3.
Tamoxifen prevents recurrence of breast cancer and is suggested for preventive risk-reducing therapy. Tamoxifen reduces mammographic density, a proxy for therapy response, but little is known about its effects in remodelling normal breast tissue. Our study, a substudy within the double-blinded dose-determination trial KARISMA, investigated tamoxifen-specific changes in breast tissue composition and histological markers in healthy women. We included 83 healthy women randomised to 6 months daily intake of 20, 10, 5, 2.5, 1 mg of tamoxifen or placebo. The groups were combined to “no dose” (0-1 mg), “low-dose” (2.5-5 mg) or “high-dose” (10-20 mg) of tamoxifen. Ultrasound-guided biopsies were collected before and after tamoxifen exposure. In each biopsy, epithelial, stromal and adipose tissues was quantified, and expression of epithelial and stromal Ki67, oestrogen receptor (ER) and progesterone receptor (PR) analysed. Mammographic density using STRATUS was measured at baseline and end-of-tamoxifen-exposure. We found that different doses of tamoxifen reduced mammographic density and glandular-epithelial area in premenopausal women and associated with reduced epithelium and increased adipose tissue. High-dose tamoxifen also decreased epithelial ER and PR expressions in premenopausal women. Premenopausal women with the greatest reduction in proliferation also had the greatest epithelial reduction. In postmenopausal women, high-dose tamoxifen decreased the epithelial area with no measurable density decrease. Tamoxifen at both low and high doses influences breast tissue composition and expression of histological markers in the normal breast. Our findings connect epithelial proliferation with tissue remodelling in premenopausal women and provide novel insights to understanding biological mechanisms of primary prevention with tamoxifen.  相似文献   
4.
5.
Modified-release opioids are often prescribed for the management of moderate to severe acute pain following total hip and knee arthroplasty, despite recommendations against their use due to increasing concerns regarding harm. The primary objective of this multicentre study was to examine the impact of modified-release opioid use on the incidence of opioid-related adverse events compared with immediate-release opioid use, among adult inpatients following total hip or knee arthroplasty. Data for total hip and knee arthroplasty inpatients receiving an opioid analgesic for postoperative analgesia during hospitalisation were collected from electronic medical records of three tertiary metropolitan hospitals in Australia. The primary outcome was the incidence of opioid-related adverse events during hospital admission. Patients who received modified with or without immediate-release opioids were matched to those receiving immediate-release opioids only (1:1) using nearest neighbour propensity score matching with patient and clinical characteristics as covariates. This included total opioid dose received. In the matched cohorts, patients given modified-release opioids (n = 347) experienced a higher incidence of opioid-related adverse events overall, compared with those given immediate-release opioids only (20.5%, 71/347 vs. 12.7%, 44/347; difference in proportions 7.8% [95%CI 2.3–13.3%]). Modified-release opioid use was associated with an increased risk of harm when used for acute pain during hospitalisation after total hip or knee arthroplasty.  相似文献   
6.
7.
8.
Pharmaceutical Chemistry Journal - Metformin hydrochloride is widely used to treat diabetes mellitus. This review presents its physical and chemical properties and discusses methods of analysis...  相似文献   
9.
Pharmaceutical Research - One of the major reasons why central nervous system (CNS)-drug development has been challenging in the past, is the barriers that prevent substances entering from the...  相似文献   
10.
Khadka  J.  Ratcliffe  J.  Hutchinson  C.  Cleland  J.  Mulhern  B.  Lancsar  E.  Milte  R. 《Quality of life research》2022,31(9):2849-2865
Quality of Life Research - To evaluate the construct (convergent and known group) validity of the Quality-of-Life-Aged Care Consumer (QOL-ACC), an older-person-specific quality-of-life measure...  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