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   18226篇
  免费   1364篇
  国内免费   467篇
耳鼻咽喉   864篇
儿科学   590篇
妇产科学   126篇
基础医学   2056篇
口腔科学   786篇
临床医学   2326篇
内科学   2515篇
皮肤病学   28篇
神经病学   732篇
特种医学   941篇
外国民族医学   2篇
外科学   3231篇
综合类   2732篇
现状与发展   2篇
一般理论   1篇
预防医学   882篇
眼科学   111篇
药学   1382篇
  9篇
中国医学   446篇
肿瘤学   295篇
  2024年   28篇
  2023年   337篇
  2022年   465篇
  2021年   715篇
  2020年   778篇
  2019年   706篇
  2018年   749篇
  2017年   703篇
  2016年   700篇
  2015年   718篇
  2014年   1317篇
  2013年   1353篇
  2012年   1082篇
  2011年   1213篇
  2010年   961篇
  2009年   955篇
  2008年   940篇
  2007年   881篇
  2006年   752篇
  2005年   643篇
  2004年   560篇
  2003年   462篇
  2002年   408篇
  2001年   350篇
  2000年   269篇
  1999年   265篇
  1998年   214篇
  1997年   195篇
  1996年   159篇
  1995年   159篇
  1994年   136篇
  1993年   110篇
  1992年   93篇
  1991年   84篇
  1990年   50篇
  1989年   59篇
  1988年   49篇
  1987年   45篇
  1986年   42篇
  1985年   71篇
  1984年   45篇
  1983年   31篇
  1982年   48篇
  1981年   29篇
  1980年   28篇
  1979年   24篇
  1978年   15篇
  1977年   21篇
  1976年   17篇
  1975年   7篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
The objective of this paper was to assess the link between premature mortality and a combination of neighbourhood contextual (environmental and health) and compositional (socioeconomic and demographic) characteristics. We statistically and spatially examined six environmental variables (ultrafine particles, carcinogenic and non-carcinogenic pollutants, pollution released to air, tree cover, and walkability index), six health service indicators (number health providers, breast, colorectal and cervical cancer screening uptake rates, student nutrition program uptake rates, and healthy food index), and eight socioeconomic indicators (total income, Gini coefficient, two age categories – below and above 40 years, proportion of females to males, visible minorities, Indigenous peoples, education, less than grade 9) among 140 neighbourhoods of the City of Toronto in Ontario (Canada). We applied principal component analysis to identify patterns and to reduce the number of explanatory variables into combined component axes that represent unique variation in these confounded and overlapping factors. We then applied regression analysis to model the relationship between the indices of enviro-health and socioeconomics and their potential relationship with premature mortality. Residual spatial analysis was used to investigate any remaining spatial structure (such as neighbourhoods with higher residual premature mortality rates). Neighbourhood Equity Index was correlated with our enviro-health and socioeconomic indices. Premature mortality within neighbourhoods was predicted by poor cancer screenings, pollution, lack of tree canopy, increased uptake of student nutrition programs and high walkability index. A negative association between premature mortality and pollution was associated low walkability index and presence of visible minorities within neighbourhoods. There was some unexplained residual spatial variation in our model of premature mortality - especially along the shores of Lake Ontario and in neighbourhoods with major highways or road corridors: premature mortality in Toronto neighbourhoods was higher than expected along highway-corridor neighbourhoods and shorelines. Our analysis revealed a significant relationship between neighbourhood contextual features – both environmental and health – and premature mortality, suggesting that these contextual components of neighbourhoods can predict rates of urban premature mortality in Toronto.  相似文献   
12.
13.
本文回顾了Er:YAG激光活化根管冲洗技术的最新研究进展,包括光子诱导光声流(photon initiated photoacoustic streaming,PIPS)技术和冲击波增强发射光声流(shock wave enhanced emission photoacoustic streaming,SWEEPS)技术,探讨Er:YAG激光预处理桩道的原理、优点以及对纤维桩粘接强度的影响,以期为临床选择适宜的桩道处理方法提供新思路。  相似文献   
14.
Background/objectiveObstructive sleep apnea (OSA) is independently associated with dyslipidemia, a surrogate marker of atherosclerosis. Low-density lipoprotein (LDL)-cholesterol is accepted as a major independent risk factor for cardiovascular disease. However, non-high-density lipoprotein (HDL)-cholesterol is a better marker of atherogenic dyslipidemia and recommended as a target of lipid lowering therapy. We aimed to assess the prevalence of atherogenic dyslipidemia, and relationship between OSA severity and serum LDL-cholesterol and non-HDL cholesterol levels in OSA patients.MethodsWe retrospectively evaluated treatment naïve 2361 subjects admitted to the sleep laboratory of a university hospital for polysomnography. All subjects’ lipid profile including total cholesterol, LDL-cholesterol, HDL-cholesterol, triglycerides, and non-HDL-cholesterol were measured.ResultsOut of 2361 patients (mean age 49.6 ± 11.9 years; 68.9% male, apnea-hypopnea index 36.6 ± 28.4/h), 185 (7.8%) had no OSA and 2176 (92.2%) had OSA. Atherogenic dyslipidemia prevalence was high (57–66%) in OSA patients, and especially increased in severe OSA compared to other groups (p < 0.05). Though total and LDL-cholesterol did not differ between those with and without OSA, non-HDL-cholesterol (p = 0.020), and triglycerides (p = 0.001) were higher and HDL-cholesterol levels (p = 0.018) were lower in OSA patients than non-OSA. Non-HDL-cholesterol was significantly correlated with OSA severity (p < 0.001) and hypoxia parameters (p < 0.01), whereas LDL-cholesterol showed no correlation.ConclusionsAtherogenic dyslipidemia is highly prevalent and non-HDL-cholesterol levels are significantly increased, predominantly in severe OSA patients. Non-HDL-cholesterol but not LDL-cholesterol, is significantly correlated with OSA severity and hypoxia parameters. Therefore, it could be better to use non-HDL-cholesterol, which is a guideline recommended target of lipid therapy, as a marker of atherosclerotic cardiovascular risk in OSA patients.  相似文献   
15.
16.
《Clinical breast cancer》2020,20(5):e584-e588
IntroductionSentinel lymph node biopsy (SLNB) is the standard procedure for axillary staging in breast cancer. There is a lack of consistency in studies reporting on upper limb morbidity after SLNB. We present a prospective study evaluating upper limb function after SLNB using the validated quickDASH questionnaire.Materials and MethodsConsecutive patients who underwent wide local excision and SLNB were included in the study. Arm function was assessed using the quickDASH questionnaire at 3 time points – prior to surgery and 2 weeks and 3 months after SLNB. The scores obtained were labeled as A, B, and C respectively. The mean and median scores were compared using the paired t test and Wilcoxon signed rank test.ResultsNinety-nine patients met all inclusion criteria and were included in the final analysis. The mean A, B, and C scores were 8.46, 16.05, and 13.36. The median A, B, and C scores were 2.27, 7.5, and 4.54. There was a statistically significant difference between mean and median A and B scores, B and C scores, and A and C scores. A similar trend was observed in patients with better preoperative upper limb function. Patients with a higher body mass index had significantly worse B and C scores.ConclusionThere is a significant deterioration in upper limb function following SLNB. This improves at 3 months but does not reach baseline levels. Larger studies with long-term follow-up are required to establish the extent of upper limb functional morbidity and natural course of functional recovery after SLNB.  相似文献   
17.
近年来,医疗器械口咽通气道产品的注册数量日益增加,针对该产品的相关咨询也逐渐增多。但该产品暂无相关的注册技术审查指导原则,以致该产品的注册申报资料经常出现一些共性问题。现根据医疗器械口咽通气道产品相关法规和标准,对日常工作中遇到的常见问题进行归纳,分析该产品注册申报中的技术审评要求及共性问题,并给出对策或建议。  相似文献   
18.
《Surgery (Oxford)》2021,39(9):591-597
Infections of the ear, nose and throat are common. The majority of these infections are managed by the primary care physicians and they settle with conservative and medical management. However, a small group can progress to become troublesome and develop complications to the extent that they may require surgical intervention. Some of the infections can lead to life-threatening complications, therefore awareness and correct diagnosis along with appropriate management is paramount. Foreign bodies in the ear, nose and throat are commonly encountered. The location and type of foreign body can have an implication on the urgency of action and the possible complications. In this article the common ENT infections and foreign bodies and their management are discussed.  相似文献   
19.

Background and study aims

Acute upper gastrointestinal bleeding is one of the main causes of hospitalisation. The purpose of this study was to determine the prognostic factors in non-variceal upper gastrointestinal bleeding.

Patients and methods

Clinical outcomes, demographic and laboratory variables of the subjects were collected from the HIS software and national code with the SQL format from three hospitals in Qazvin. The data were linked to the database software designed by the author. Clinical and upper endoscopic findings of patients’ records were collected through a questionnaire form in the designed software database.

Results

In this study, 29.2% of patients with favourable outcome and 64.2% of patients with unfavourable clinical outcomes had a history of anticoagulant drug use before hospitalisation (p?<?0.001). The prevalence of chronic cardiovascular disease, chronic liver disease, chronic lung disease, diabetes and dialysis was higher in subjects with poor clinical outcomes than those with a favourable clinical outcome.53.1% of subjects with favourable clinical outcome and 90.5% of subjects with undesirable clinical outcomes received packed red blood cell transfusion (p?<?0.001). 16.1% of subjects with desirable clinical outcome and 86.3% of subjects with undesirable clinical outcomes received endoscopic haemostatic treatment which was statistically significant (p?<?0.001).

Conclusion

Undesirable clinical outcome in patients with acute non-variceal upper gastrointestinal bleeding has a significant statistical association with longer hospitalisation, chronic underlying disease, anticoagulant administration, packed red blood cell infusion, higher Forrest stage, low systolic blood pressure, higher age, low haemoglobin, low platelet count, high INR and high BUN at the onset of diagnosis.  相似文献   
20.
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