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   8383篇
  免费   606篇
  国内免费   27篇
耳鼻咽喉   74篇
儿科学   297篇
妇产科学   299篇
基础医学   1241篇
口腔科学   165篇
临床医学   852篇
内科学   1551篇
皮肤病学   185篇
神经病学   795篇
特种医学   209篇
外科学   792篇
综合类   68篇
一般理论   5篇
预防医学   981篇
眼科学   193篇
药学   719篇
中国医学   10篇
肿瘤学   580篇
  2023年   104篇
  2022年   68篇
  2021年   244篇
  2020年   197篇
  2019年   270篇
  2018年   303篇
  2017年   247篇
  2016年   277篇
  2015年   278篇
  2014年   343篇
  2013年   482篇
  2012年   667篇
  2011年   645篇
  2010年   369篇
  2009年   322篇
  2008年   522篇
  2007年   490篇
  2006年   457篇
  2005年   412篇
  2004年   366篇
  2003年   330篇
  2002年   271篇
  2001年   91篇
  2000年   85篇
  1999年   75篇
  1998年   64篇
  1997年   45篇
  1996年   30篇
  1995年   33篇
  1994年   33篇
  1993年   26篇
  1992年   29篇
  1991年   29篇
  1990年   41篇
  1989年   39篇
  1988年   47篇
  1987年   30篇
  1986年   35篇
  1985年   43篇
  1984年   31篇
  1983年   26篇
  1979年   33篇
  1978年   38篇
  1977年   35篇
  1975年   39篇
  1974年   35篇
  1973年   28篇
  1972年   29篇
  1970年   22篇
  1969年   22篇
排序方式: 共有9016条查询结果,搜索用时 15 毫秒
1.
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   
2.
3.
Many environmental risk factors for hepatobiliary cancers are known but whether they are associated with specific cancer types is unclear. We present here a novel approach of assessing standardized incidence ratios (SIRs) of previously diagnosed comorbidities for hepatocellular carcinoma (HCC), gallbladder cancer (GBC), cholangiocarcinoma (CCA) and ampullary cancer. The 13 comorbidities included alcohol and nonalcohol related liver disease, chronic obstructive pulmonary disease, gallstone disease, viral and other kinds of hepatitis, infection of bile ducts, hepatic and other autoimmune diseases, obesity and diabetes. Patients were identified from the Swedish Inpatient Register from 1987 to 2018, and their cancers were followed from 1997 onwards. SIRs for HCC were 80 to 100 in men and women diagnosed with hepatitis C virus and they were also >10 in patients diagnosed with hepatitis B virus, other kind of hepatitis, hepatic autoimmune disease and nonalcohol related liver disease. Many of these risks, as well as alcohol related liver disease, were either specific to HCC or were shared with intrahepatic CCA. For GBC, CCA and ampullary cancer infection of bile ducts was the main risk factor. Gallstone disease, nonhepatic autoimmune diseases and diabetes were associated with all hepatobiliary cancers. The limitations of the study include inability to cover some rare risk factors and limited follow-up time. Many of the considered comorbidities are characterized by chronic inflammation and/or overt immune disturbance in autoimmune diseases. The results suggest that local chronic inflammation and a related immune disturbance is the carcinogenic trigger for all these cancers.  相似文献   
4.
5.

Objectives

Professional athletes undergo annual pre-season laboratory screening, although clinical evidence supporting the practice is limited and no uniform set of guidelines on pre-season laboratory screening exists. The aim of this study was to assess the clinical value of annual pre-season laboratory screening tests for a major professional sports team over multiple years.

Design

Retrospective chart review.

Methods

A retrospective analysis was performed of all laboratory results as well as screening ECGs for a single major professional sports team over a 9-year timeframe (2009–2017).

Results

The data show that 10.01% of initial screening test results were abnormal and 40.32% of abnormal tests resulted in additional testing. Overall, only 0.35% of initial tests resulted in a clinically significant outcome. Non-US born players showed a significantly higher average rate of abnormal tests/year compared to US-born players (p-value 0.006), but there was no difference in clinically significant outcomes. There was no relationship between athlete age and laboratory screening outcomes.

Conclusions

In our study population, yearly pre-season laboratory screening of professional athletes did not yield substantial clinically significant outcomes and would not be warranted under normal clinical standards. Future best practice guidelines should combine research concerning effects of family medical history, race, gender, country of origin, and type of sport on athlete health when creating recommendations for which pre-season laboratory screenings may be pertinent even with evidence of little utility.  相似文献   
6.
Objective: Multiple sclerosis (MS) is associated with prospective memory (PM) deficits, which may increase the risk of poor functional/health outcomes such as medication non-adherence. This study examined the potential benefits of selective reminding to enhance PM functioning in persons with MS.

Method: Twenty-one participants with MS and 22 healthy adults (HA) underwent a neuropsychological battery including a Selective Reminding PM (SRPM) experimental procedure. Participants were randomly assigned to either: (1) a selective reminding condition in which participants learn (to criterion) eight prospective memory tasks in a Selective Reminding format; or (2) a single trial encoding condition (1T).

Results: A significant interaction was demonstrated, with MS participants receiving greater benefit than HAs from the SR procedure in terms of PM performance. Across diagnostic groups, participants in the SR conditions (vs. 1T conditions) demonstrated significantly better PM performance. Individuals with MS were impaired relative to HAs in the 1T condition, but performance was statistically comparable in the SR condition.

Conclusions: This preliminary study suggests that selective reminding can be used to enhance PM cue detection and retrieval in MS. The extent to which selective reminding of PM is effective in naturalistic settings and for health-related behaviours in MS remains to be determined.  相似文献   

7.
8.
Abstract

The occupational hazards and respiratory symptoms of domestic cleaners in USA are largely unknown. We conducted a cross-sectional study among 56 Hispanic female domestic cleaner on their health status and frequency of cleaning products used and tasks performed. While women used multi-use products (60.0%) and toilet bowl cleaners (51.8%) most days of the week, many (39.3%) reported not using personal protective equipment while cleaning. Itchy/watery eyes (61.8%) and itchy nose (56.4%) were the most frequently reported symptoms. A history of physician-diagnosed asthma was reported by 14.3% while 33.9% had symptoms of bronchial hyperresponsiveness (BHR). In conclusion, this vulnerable population has high prevalence of physician-diagnosis asthma and BHR symptoms and is potentially exposed to myriad occupational hazards. Further research exploring associations between products use, cleaning tasks and respiratory symptoms is warranted.  相似文献   
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