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   34245篇
  免费   3620篇
  国内免费   832篇
耳鼻咽喉   342篇
儿科学   484篇
妇产科学   550篇
基础医学   2492篇
口腔科学   9784篇
临床医学   2486篇
内科学   3040篇
皮肤病学   739篇
神经病学   901篇
特种医学   415篇
外国民族医学   3篇
外科学   2185篇
综合类   3592篇
现状与发展   4篇
预防医学   1714篇
眼科学   222篇
药学   6355篇
  39篇
中国医学   1721篇
肿瘤学   1629篇
  2023年   598篇
  2022年   599篇
  2021年   1288篇
  2020年   1469篇
  2019年   1411篇
  2018年   1359篇
  2017年   1290篇
  2016年   1357篇
  2015年   1309篇
  2014年   2014篇
  2013年   2687篇
  2012年   1861篇
  2011年   2005篇
  2010年   1546篇
  2009年   1458篇
  2008年   1439篇
  2007年   1491篇
  2006年   1332篇
  2005年   1308篇
  2004年   1139篇
  2003年   1060篇
  2002年   905篇
  2001年   800篇
  2000年   680篇
  1999年   594篇
  1998年   510篇
  1997年   504篇
  1996年   455篇
  1995年   416篇
  1994年   376篇
  1993年   321篇
  1992年   323篇
  1991年   231篇
  1990年   237篇
  1989年   241篇
  1988年   217篇
  1987年   174篇
  1986年   151篇
  1985年   241篇
  1984年   212篇
  1983年   166篇
  1982年   183篇
  1981年   170篇
  1980年   121篇
  1979年   86篇
  1978年   73篇
  1977年   71篇
  1976年   56篇
  1975年   44篇
  1974年   33篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
《Journal of endodontics》2022,48(1):102-108
IntroductionThe first outbreak of coronavirus disease 2019 (COVID-19) in the United States resulted in a nationwide closure of dental offices that created an oral health crisis. The aim of this observational study was to analyze and compare the characteristics of patients who visited 2 private endodontics offices from March 16 to May 31, 2020, compared with the same period in 2019.MethodsDemographic, diagnostic, and procedural data of 1520 (693 in 2020 and 827 in 2019) patient visits were collected. Bivariate and multiple logistic regression analyses were used to assess the impact of the COVID-19 outbreak on patient-related variables.ResultsBivariate analyses showed that the number of patient visits decreased in April and May 2020 (P < .0001). In 2020, patients’ self-reported pain level was higher, they were more frequently diagnosed with pulp necrosis and acute apical abscess, and they received more incisions for drainage (P < .05). Multiple logistic regression analyses showed that the COVID-19 outbreak was associated with less visits for older patients (>49.5 years) (odds ratio [OR] = 0.720; 95% confidence interval [CI], 0.573–0.906), more patients with kidney diseases (OR = 2.690; 95% CI, 1.143–6.331), higher levels of pain on percussion (OR = 2.277; 95% CI, 1.718–3.016), less cases with previously initiated treatment (OR = 0.242; 95% CI, 0.080–0.731), less periapical diagnoses of asymptomatic apical periodontitis (OR = 0.510; 95% CI, 0.306–0.849), and a higher number of nonsurgical root canal treatments (OR = 2.073; 95% CI, 1.397–3.074) and apicoectomies (OR = 2.799; 95% CI, 1.367-5.729).ConclusionsThese findings show that the public health burden of endodontic infections was more intense during the initial outbreak of COVID-19.  相似文献   
3.
4.
5.
There is growing, but inconsistent evidence suggesting oestrogen may play a key role in lung cancer development, especially among never-smoking women for whom lung cancer risk factors remain largely elusive. Using the China Kadoorie Biobank, a large-scale prospective cohort with 302 510 women aged 30 to 79 years recruited from 10 regions in China during 2004 to 2008, we assessed the risk of lung cancer death among self-reported never-smoking women who were cancer-free at baseline, in relation to age at menarche, age at menopause, time since menopause, prior use of oral contraceptives (OCP), number of livebirths, breastfeeding and age at first livebirth. Women were followed up to December 31, 2016 with linkage to mortality data. Hazard ratios (HR) and 95% confidence intervals (CI) were estimated using Cox regression, adjusting for key confounders including several socio-demographic, environmental and lifestyle factors. Among 287 408 never-smoking women, 814 died from lung cancer with a median follow-up of 10.3 years. Women who had used OCP within 15 years prior to baseline had a significantly higher hazard of lung cancer death compared with never-users: HR = 1.85 (95% CI: 1.14-3.00) and risk increased by 6% with each additional year of use: HR = 1.06 (1.01-1.10). Among parous women, the hazard of lung cancer death increased by 13% with each single livebirth: HR = 1.13 (1.05-1.23); and among post-menopausal women, the risk increased by 2% with each year since menopause: HR = 1.02 (1.01-1.04). These results suggest that reproductive factors which were proxies for lower endogenous oestrogen level, for example, longer duration of OCP use, could play a role in lung cancer development.  相似文献   
6.
The importance of the left atrial appendage (LAA) as the source of thromboembolism including stroke in patients with nonvalvular atrial fibrillation is well documented, with more than 90% of ischemic strokes related to a LAA thrombus. Although oral anticoagulation has been the standard of care, approximately 50% to 60% of patients either have contraindications to oral anticoagulation or do not continue the medication beyond the first year. This led to the development of local site-specific therapy to occlude the LAA by either surgical or transcatheter means. Despite marked advancements, incomplete LAA closure with surgical and transcatheter approaches remains frequent. The etiology of incomplete LAA closure and its clinical implications remain unclear. Multiple strategies are in development including changes in deployment techniques, a new device design, and alternative approaches to leak closure.  相似文献   
7.
PurposeTo compare the characteristics of polidocanol (POL) and ethanolamine oleate (EO) sclerosing foams produced by a Shirasu porous glass membrane (SPGM) device with those made using a 3-way stopcock (3WSC).Materials and MethodsFoam half-life times were measured in an ex-vivo benchtop study. Computed tomography (CT) images of each foam were obtained over the time course, and a CT texture analysis was conducted. The bubble size in each foam was measured by an optical microscope.ResultsMedian foam half-life times were longer in the SPGM group than in the 3WSC group (POL: 198 vs 166 s, P = .02; EO: 640 vs 391 s, P < .01). In the CT texture analysis, median standard deviation (SD) and entropy (randomness) were lower, and median energy (uniformity) and gray-level cooccurrence matrix (GLCM) homogeneity were higher in the SPGM group than in the 3WSC group (POL SD: at 30 s and 50–300 s; POL entropy: at 0–60 s; EO SD: at 0–600 s; EO entropy: at 0–460 s; POL energy: at 0–40 s; POL GLCM homogeneity: at 0–250 s; EO energy: at 0–360 s; EO GLCM homogeneity: at 0–480 s; all P < .05). Median bubble diameters in the SPGM group and in the 3WSC group were 69 and 83 μm (P < .01), respectively, in the POL foam; and 36 and 36 μm (P = .45), respectively, in the EO foam.ConclusionsPOL and EO foams had greater uniformity and longer foam half-life time when prepared with an SPGM device than with a 3WSC.  相似文献   
8.
9.
Trismus is one of the most debilitating and treatment-resistant complications resulting from head and neck oncological treatments. The objective of this study was to assess how primary tumour variables could assist in predicting chronic trismus. From a (retrospective) oncological database (Department of Oral and Maxillofacial Surgery, University Hospitals Leuven), tumour-related, surgical, and oral functional variables were reviewed. Contributing factors for chronic trismus, defined as a mouth opening of less than 35 mm, at least one year after treatment for oral squamous cell cancer, were assessed via logistic regression. A mediational analysis was conducted on the significant predictive variables. Thirteen out of 52 patients were observed to have chronic trismus. A significantly higher prevalence of trismus was found for increasing clinical T classification (p < 0.01), tumours based in the maxilla or the retromolar trigone (p = 0.04), after adjuvant radiotherapy (p = 0.04), and/or with masticatory muscle tumour invasion (p ≤ 0.02). Furthermore, radiotherapy significantly impacted T classification in chronic trismus, while T classification was significantly related to masticatory muscle invasion. Although radiotherapy and clinical T classification are well-established risk factors for postoperative trismus, masticatory muscle invasion should be considered as one of the main predictive factors.  相似文献   
10.
We designed a systematic literature review to identify available evidence on adherence to and persistence with antidiabetic medication in people with type 2 diabetes (T2D). Electronic screening and congress searches identified real-world noninterventional studies (published between 2010 and October 2020) reporting estimates of adherence to and persistence with antidiabetic medication in adults with T2D, and associations with glycaemic control, microvascular and/or macrovascular complications, hospitalizations and healthcare costs. Ninety-two relevant studies were identified, the majority of which were retrospective and reported US data. The proportions of patients considered adherent (median [range] 51.2% [9.4%-84.3%]) or persistent (median [range] 47.7% [16.9%-94.0%]) varied widely across studies. Multiple studies reported an association between greater adherence/persistence and greater reductions in glycated haemoglobin levels. Better adherence/persistence was associated with fewer microvascular and/or macrovascular outcomes, although there was little consistency across studies in terms of which outcomes were improved. More adherent and more persistent patients were typically less likely to be hospitalized or to have emergency department visits/admissions and spent fewer days in hospital annually than less adherent/persistent patients. Greater adherence and persistence were generally associated with lower hospitalization costs, higher pharmacy costs and lower or budget-neutral total healthcare costs compared with lower adherence/persistence. In conclusion, better adherence and persistence in people with T2D is associated with lower rates of microvascular and/or macrovascular outcomes and inpatient hospitalization, and lower or budget-neutral total healthcare expenditure. Education and treatment strategies to address suboptimal adherence and persistence are needed to improve clinical and economic outcomes.  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