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   11896篇
  免费   543篇
  国内免费   13篇
耳鼻咽喉   42篇
儿科学   485篇
妇产科学   332篇
基础医学   924篇
口腔科学   186篇
临床医学   927篇
内科学   3120篇
皮肤病学   147篇
神经病学   871篇
特种医学   302篇
外科学   1452篇
综合类   109篇
预防医学   1853篇
眼科学   108篇
药学   404篇
中国医学   2篇
肿瘤学   1188篇
  2024年   6篇
  2023年   542篇
  2022年   756篇
  2021年   891篇
  2020年   1009篇
  2019年   528篇
  2018年   506篇
  2017年   549篇
  2016年   575篇
  2015年   527篇
  2014年   1051篇
  2013年   735篇
  2012年   417篇
  2011年   317篇
  2010年   656篇
  2009年   633篇
  2008年   248篇
  2007年   303篇
  2006年   241篇
  2005年   216篇
  2004年   160篇
  2003年   157篇
  2002年   177篇
  2001年   152篇
  2000年   121篇
  1999年   136篇
  1998年   94篇
  1997年   77篇
  1996年   89篇
  1995年   75篇
  1994年   61篇
  1993年   54篇
  1992年   65篇
  1991年   49篇
  1990年   63篇
  1989年   47篇
  1988年   42篇
  1987年   11篇
  1986年   10篇
  1985年   19篇
  1984年   19篇
  1983年   17篇
  1982年   5篇
  1980年   5篇
  1979年   7篇
  1975年   3篇
  1973年   5篇
  1972年   4篇
  1971年   3篇
  1970年   4篇
排序方式: 共有10000条查询结果,搜索用时 233 毫秒
41.
Harinakshi Sanikini  David C. Muller  Marisa Sophiea  Sabina Rinaldi  Antonio Agudo  Eric J. Duell  Elisabete Weiderpass  Kim Overvad  Anne Tjønneland  Jytte Halkjær  Marie-Christine Boutron-Ruault  Franck Carbonnel  Iris Cervenka  Heiner Boeing  Rudolf Kaaks  Tilman Kühn  Antonia Trichopoulou  Georgia Martimianaki  Anna Karakatsani  Valeria Pala  Domenico Palli  Amalia Mattiello  Rosario Tumino  Carlotta Sacerdote  Guri Skeie  Charlotta Rylander  María-Dolores Chirlaque López  Maria-Jose Sánchez  Eva Ardanaz  Sara Regnér  Tanja Stocks  Bas Bueno-de-Mesquita  Roel C.H. Vermeulen  Dagfinn Aune  Tammy Y.N. Tong  Nathalie Kliemann  Neil Murphy  Marc Chadeau-Hyam  Marc J. Gunter  Amanda J. Cross 《International journal of cancer. Journal international du cancer》2020,146(4):929-942
Obesity has been associated with upper gastrointestinal cancers; however, there are limited prospective data on associations by subtype/subsite. Obesity can impact hormonal factors, which have been hypothesized to play a role in these cancers. We investigated anthropometric and reproductive factors in relation to esophageal and gastric cancer by subtype and subsite for 476,160 participants from the European Prospective Investigation into Cancer and Nutrition cohort. Multivariable hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using Cox models. During a mean follow-up of 14 years, 220 esophageal adenocarcinomas (EA), 195 esophageal squamous cell carcinomas, 243 gastric cardia (GC) and 373 gastric noncardia (GNC) cancers were diagnosed. Body mass index (BMI) was associated with EA in men (BMI ≥30 vs. 18.5–25 kg/m2: HR = 1.94, 95% CI: 1.25–3.03) and women (HR = 2.66, 95% CI: 1.15–6.19); however, adjustment for waist-to-hip ratio (WHR) attenuated these associations. After mutual adjustment for BMI and HC, respectively, WHR and waist circumference (WC) were associated with EA in men (HR = 3.47, 95% CI: 1.99–6.06 for WHR >0.96 vs. <0.91; HR = 2.67, 95% CI: 1.52–4.72 for WC >98 vs. <90 cm) and women (HR = 4.40, 95% CI: 1.35–14.33 for WHR >0.82 vs. <0.76; HR = 5.67, 95% CI: 1.76–18.26 for WC >84 vs. <74 cm). WHR was also positively associated with GC in women, and WC was positively associated with GC in men. Inverse associations were observed between parity and EA (HR = 0.38, 95% CI: 0.14–0.99; >2 vs. 0) and age at first pregnancy and GNC (HR = 0.54, 95% CI: 0.32–0.91; >26 vs. <22 years); whereas bilateral ovariectomy was positively associated with GNC (HR = 1.87, 95% CI: 1.04–3.36). These findings support a role for hormonal pathways in upper gastrointestinal cancers.  相似文献   
42.
ObjectiveCurrent estimates of endometriosis prevalence and incidence are highly variable, leading to uncertainty regarding true endometriosis frequency or validity of quantified changes over time. We present a comprehensive review of the prevalence, incidence, and stage of endometriosis worldwide as reported over the past 30 years.Data SourcesWe conducted a systematic search of observational studies using the PubMed, Web of Science, EMBASE, and CINAHL databases to identify research papers published in English between January 1989 and June 2019. Search terminologies were limited to titles containing endometriosis and prevalence or incidence, or epidemiology, or frequency, or occurrence, or statistics.Methods of Study SelectionTwo independent reviewers screened abstracts for study eligibility, and data from included studies were abstracted.Tabulation, Integration, and ResultsOverall, 69 studies describing the prevalence and/or incidence of endometriosis met the inclusion criteria. Among these, 26 studies involved general population samples, 17 of which were from regional/national hospitals or insurance claims systems. The other 43 studies were conducted in single clinic or hospital settings. Prevalence estimates for endometriosis widely varied from 0.2% to 71.4% depending on the population sampled. The prevalence reported in general population studies ranged from 0.7% to 8.6%, whereas that reported in single clinic- or hospital-based studies ranged from 0.2% to 71.4%. When defined by indications for diagnosis, endometriosis prevalence ranged from 15.4% to 71.4% among women with chronic pelvic pain, 9.0% to 68.0% among women presenting with infertility, and 3.7% to 43.3% among women undergoing tubal sterilization. A meta-regression was conducted with year as the predictor of prevalence. No trend across time was observed among “general population in country/region” studies (β = 0.04, p = .12) or among “single hospital or clinic” studies (β = ˗0.02, p = .34); however, a decrease over time was observed among general population studies abstracted from health systems or insurance systems (β = −0.10, p = .005).ConclusionAs with all human studies, population sampling and study design matter. Heterogeneity of inclusion and diagnostic criteria and selection bias overwhelmingly account for variability in endometriosis prevalence estimated across the literature. Thus, it is difficult to conclude if the lack of observed change in frequency and distribution of endometriosis over the past 30 years is valid.  相似文献   
43.
44.
AimTo investigate the impact of circumferential tumour location on neoadjuvant chemoradiotherapy (CRT) response and its prognostic value for locally advanced rectal cancer (LARC) patients after CRT and surgery.MethodsA retrospective study was performed on 486 patients with LARC who received neoadjuvant CRT and surgical treatment. The rate of pathological complete response (pCR) and survival among patients with anteriorly, laterally, and posteriorly located tumours were compared. Logistic regression was performed to identify pCR predictors.ResultsThe anterior tumours exhibited the highest pCR rate of 26.7%, which was slightly higher than the 20.0% and 12.3% for lateral and posterior tumours, respectively (P = 0.006). The 5-year Overall survival (OS) rates after CRT were similar among the anterior, lateral, and posterior groups (anterior vs lateral vs posterior: 81.1% vs 89.9% vs 84.1%, P = 0.6368). Multivariate analysis revealed that the circumferential tumour location, post-CRT serum CEA and post-CRT tumour thickness measured by MRI were independently correlated with achieving pCR.ConclusionThis study is the first, to the best of our knowledge, to show that anterior LARC exhibited the highest pCR rate after neoadjuvant CRT. Patients with anterior rectal cancers do not have different prognoses from those with non-anterior cancers if they undergo neoadjuvant CRT.  相似文献   
45.
46.
47.
PurposeTo determine anxiety, stress, and quality of life (QoL) in parents of children who are diagnosed with biliary atresia (BA).MethodsParents of BA patients (0–3 years) completed validated questionnaires at three time points: at first hospitalization (T0); 1–2 months post diagnosis (T1); and 2–3 years post diagnosis (T2). Results are presented in medians (min-max).ResultsWe included 52 parents (age 31 [24–51 y], 31 females) of 30 BA patients. In fathers, neither anxiety nor stress levels significantly differed from reference values. Mothers reported significantly higher anxiety levels compared to reference values (T0: 48 vs 35, p = 0.001; T1: 43 vs 35, p = 0.03; T2: 37 vs 35, p = 0.04), which significantly decreased over time (-23% between T0 and T2: p = 0.04). Stress in mothers was significantly higher at T1 than at T2 (+35%, p = 0.02), but was not significantly different from reference values at each time point (T0: 17 vs 14, p = 0.07; T1: 18 vs 14, p = 0.09; T2: 13 vs 14, p = 0.52).The overall QoL in mothers and fathers was rather unaffected.ConclusionsParticularly mothers of infants diagnosed with BA report high anxiety levels up to three years after diagnosis. The overall QoL of parents is rather unaffected after diagnosing BA in their child.Level of EvidenceLevel 2.  相似文献   
48.
There is a pathophysiological and clinical link between atherosclerosis and skeletal fragility. Abdominal aortic calcifications (AACs) can be considered as a marker of coexistent atherosclerotic disease and osteoporosis. Indeed, AACs have been associated with alterations in bone strength and severe AACs predicted vertebral fractures in post-menopausal women and older men, independent of densitometric diagnosis of osteoporosis. Although quantitative computed tomography is the gold standard for evaluation of AACs, dual-energy x-ray absorptiometry can be considered as a cost-effective tool to identify and quantify AACs in clinical practice. This article provides an update on diagnostic aspects and clinical relevance of AACs as predictor of fractures in patients at high cardiovascular risk.  相似文献   
49.
50.
《Vaccine》2020,38(32):4940-4943
To determine the duration of immunity provided by the Hepatitis A vaccination (HepA), we evaluated a cohort of participants in Alaska 20 years after being immunized as infants. At recruitment, participants received two doses of inactivated HepA vaccine on one of three schedules. We conducted hepatitis A antibody (anti-HAV) testing for participants at the 20-year time-point. Seventy-five of the original 183 participants (41%) were available for follow-up. The overall anti-HAV geometric mean concentration was 29.9 mIU/mL (95% CI 22.4 mIU/mL, 39.7 mIU/mL) and 50 participants (68%) remained seropositive (titer ≥ 20 mIU/mL). Using a fractional polynomial model, the predicted percent seropositive at 25 years was 55.3%, 49.8% at 30 years and 45.7% at 35 years, suggesting that the percent sero-positive could drop below 50% earlier than previously expected. Further research is necessary to understand if protection continues after seropositivity diminishes or if a HepA booster dose may become necessary.  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