首页 | 官方网站   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   24658篇
  免费   1340篇
  国内免费   267篇
医药卫生   26265篇
  2023年   182篇
  2022年   179篇
  2021年   685篇
  2020年   475篇
  2019年   567篇
  2018年   731篇
  2017年   613篇
  2016年   694篇
  2015年   780篇
  2014年   1008篇
  2013年   1225篇
  2012年   1917篇
  2011年   1939篇
  2010年   1108篇
  2009年   1065篇
  2008年   1760篇
  2007年   1735篇
  2006年   1565篇
  2005年   1517篇
  2004年   1483篇
  2003年   1319篇
  2002年   1164篇
  2001年   208篇
  2000年   166篇
  1999年   191篇
  1998年   164篇
  1997年   134篇
  1996年   153篇
  1995年   136篇
  1994年   93篇
  1993年   115篇
  1992年   132篇
  1991年   95篇
  1990年   81篇
  1989年   99篇
  1988年   72篇
  1987年   76篇
  1986年   67篇
  1985年   57篇
  1984年   64篇
  1983年   57篇
  1982年   42篇
  1981年   46篇
  1980年   50篇
  1979年   34篇
  1978年   21篇
  1977年   28篇
  1976年   20篇
  1975年   13篇
  1974年   19篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
Colorectal cancer (CRC) screening programs help diagnose cancer precursors and early cancers and help reduce CRC mortality. However, currently recommended tests, the fecal immunochemical test (FIT) and colonoscopy, have low uptake. There is therefore a pressing need for screening strategies that are minimally invasive and consequently more acceptable to patients, most likely blood based, to increase early CRC identification. MicroRNAs (miRNAs) released from cancer cells are detectable in plasma in a remarkably stable form, making them ideal cancer biomarkers. Using plasma samples from FIT-positive (FIT+) subjects in an Italian CRC screening program, we aimed to identify plasma circulating miRNAs that detect early CRC. miRNAs were initially investigated by quantitative real-time PCR in plasma from 60 FIT+ subjects undergoing colonoscopy at Fondazione IRCCS Istituto Nazionale dei Tumori, then tested on an internal validation cohort (IVC, 201 cases) and finally in a large multicenter prospective series (external validation cohort [EVC], 1121 cases). For each endoscopic lesion (low-grade adenoma [LgA], high-grade adenoma [HgA], cancer lesion [CL]), specific signatures were identified in the IVC and confirmed on the EVC. A two-miRNA-based signature for CL and six-miRNA signatures for LgA and HgA were selected. In a multivariate analysis including sex and age at blood collection, the areas under the receiver operating characteristic curve (95% confidence interval) of the signatures were 0.644 (0.607–0.682), 0.670 (0.626–0.714) and 0.682 (0.580–0.785) for LgA, HgA and CL, respectively. A miRNA-based test could be introduced into the FIT+ workflow of CRC screening programs so as to schedule colonoscopies only for subjects likely to benefit most.  相似文献   
4.
Background:Risk behaviors are frequent among young adults and they are particularly relevant when considering healthcare students.Objectives:The study is aimed to examine the prevalence of smoking, binge drinking, physical inactivity, and excessive bodyweight in a population of healthcare students attending an Italian university.Methods:Healthcare students filled an anonymous multiple-choice questionnaire on the occasion of the occupational health visit that preceded their hospital internship. The questionnaire covered socio-demographic characteristics (including student’s working status and cohabitation) and risk behaviors. We evaluated the prevalence of risk behaviors and their association with socio-demographic characteristics.Results:The sample consisted of 494 students (65% women): 23.2% were smokers, 7.9% had excessive bodyweight, 35% did not practice any physical activity and 50% reported binge drinking at least once in the last 12 months. We found associations of male sex (30.5%) and being nursing students (29.9%) with smoking habit. The frequency of binge drinking was higher in men (38.4%), working students (53.9%), and among those who lived without family (50%). Physical inactivity was associated with female sex (44.2%) and living without family (57.1%). Finally, the co-presence of 2 risk behaviors or more was higher in men (36.8%), in nursing students (39.6%) and in working students (44.7%).Conclusions:Our findings regarding the prevalence of risk behaviors and their potential association with socio-demographic factors may be a clue to the definition of targeted strategies aimed at reducing of risk behaviors among healthcare students.Key words: risk behaviors, healthcare students, smoking, binge drinking, physical inactivity  相似文献   
5.
Background::Soft tissue sarcoma (STS) is a heterogeneous group of rare neoplasms whose aetiology is largely unknown. Dioxin and dioxin-like compounds, including 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) and polychlorinated biphenyls (PCBs), are potential risk factors for STS.Objectives:To investigate the relation of 17 PCBs congeners, assessed in human plasma, with STS risk.Methods:We conducted a case-control study in Italy, including 52 STS cases and 99 hospital-based controls. Selected PCB were extracted by high-performance liquid chromatography (HPLC) and measured with gas chromatography-mass spectrometry (GC-MS). Odds ratios (OR), and the corresponding 95% confidence intervals (CI), were estimated through multivariate logistic regression models.Results:The most frequently detected PCB congeners were 138, 170, 180 and 149 (detected in 40-77% of controls). The OR for the sum of all 17 PCB congeners was 1.20 (95% CI 0.50-2.92). In categorical analysis no consistent association was found for individual congeners and for groups based on Wolff’s classification or the degree of chlorination. For continuous estimates, borderline positive associations emerged for Wolff’s groups 2A (OR 1.23, 95% CI 0.97-1.55), 2B (OR 1.34, 95% CI 1.00-1.77, and 3 (OR 1.19, 95% CI 0.96-1.49), for moderately (OR 1.20, 95% CI 0.96-1.51) and highly (OR 1.18, 95% CI 0.99-1.41) chlorinated PCBs, and for congeners 170 (OR 1.26, 95% CI 0.98-1.63), 180 (OR 1.26, 95% CI 0.97-1.64) and 138 (OR 1.45, 95% CI 1.02-2.04).Discussion:Most associations between PCBs and STS risk were not significant, but, given the limited sample size, we cannot exclude moderate associations.Key words: Soft tissue sarcoma, polychlorinated biphenyls, epidemiology, environmental risk factors, chemical contaminants, case-control study  相似文献   
6.
7.
8.
Cardiovascular Drugs and Therapy - Available animal models of acute heart failure (AHF) and their limitations are discussed herein. A novel and preclinically relevant porcine model of decompensated...  相似文献   
9.
Clinical Oral Investigations - By means of a systematic review and network meta-analysis, this study aims to answer the following questions: (a) does the placement of a biomaterial over an...  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-23

京公网安备 11010802026262号