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   2074368篇
  免费   165473篇
  国内免费   4834篇
耳鼻咽喉   28930篇
儿科学   65869篇
妇产科学   60335篇
基础医学   296100篇
口腔科学   58201篇
临床医学   184850篇
内科学   406000篇
皮肤病学   46631篇
神经病学   171033篇
特种医学   80667篇
外国民族医学   626篇
外科学   314461篇
综合类   52491篇
现状与发展   4篇
一般理论   706篇
预防医学   163192篇
眼科学   48356篇
药学   149101篇
  1篇
中国医学   4537篇
肿瘤学   112584篇
  2018年   22035篇
  2017年   16886篇
  2016年   19128篇
  2015年   21748篇
  2014年   30849篇
  2013年   46431篇
  2012年   62822篇
  2011年   66224篇
  2010年   38856篇
  2009年   37061篇
  2008年   61616篇
  2007年   65755篇
  2006年   66203篇
  2005年   64325篇
  2004年   61926篇
  2003年   59370篇
  2002年   57282篇
  2001年   96868篇
  2000年   99161篇
  1999年   82866篇
  1998年   24100篇
  1997年   21844篇
  1996年   21768篇
  1995年   20654篇
  1994年   19094篇
  1993年   17904篇
  1992年   64807篇
  1991年   62361篇
  1990年   60314篇
  1989年   57655篇
  1988年   53495篇
  1987年   52358篇
  1986年   49305篇
  1985年   47313篇
  1984年   36331篇
  1983年   30812篇
  1982年   19198篇
  1981年   17337篇
  1979年   34094篇
  1978年   24274篇
  1977年   20278篇
  1976年   18919篇
  1975年   19855篇
  1974年   24358篇
  1973年   23473篇
  1972年   22194篇
  1971年   20359篇
  1970年   19408篇
  1969年   18372篇
  1968年   16959篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
72.
73.
74.
At this study a multi-criteria model was developed to examine the available procedures, techniques and methods of handling infectious waste in the large healthcare unit of University Regional General Hospital of Patras, Western Greece. Particularly, this study examined the: a) current legislation and Directives issued for medical waste management at Greece and among the other EU-members, b) contribution of healthcare wastes (HCW) generation rate on social and economic parameters in selected European countries, c) available procedures, techniques, and methods upon the disposal of infectious wastes at the healthcare studied, and, d) propositions for integrated management of such hazardous wastes. Specifically, the Analytic Hierarchy Process (AHP) methodology was applied under pair wise comparison matrices in two stages: 1) the scale factors and the indicators, and 2) the criteria and their sub–criteria. The assessment of these pair wise matrices included the indicators and the sub–criteria. Subsequently, two pair wise comparison matrices, upon a) the “Fulfillment of environmental objectives” indicator and b) the “Energy consumption” sub criterion, were denoted. The AHP methodology yielded good results; however there is still space of improving the environmental performance. The normalized relative weights obtained for the criteria and sub criteria motivated specific actions that have to be handled. Particularly, the results indicated a very good value in environmental management criteria due the values obtained for the commitment towards the environmental policy standards and the waste management procedures. However, further improvements on staff awareness (such as development programs to enhance sensitivity) and more green purchasing suppliers, should be further addressed.  相似文献   
75.
76.
77.
First described in 1955 in New Jersey, epizootic haemorrhagic disease (EHD) causes a severe clinical disease in wild and domestic ruminants worldwide. Epizootic haemorrhagic disease outbreaks occur in deer populations each year from summer to late autumn. The etiological agent is EHD virus (EHDV) which is a double‐stranded segmented icosahedral RNA virus. EHD virus utilizes point mutations and reassortment strategies to maintain viral fitness during infection. In 2018, EHDV serotype 2 was predominantly detected in deer in Illinois. Whole genome sequencing was conducted for two 2018 EHDV2 isolates (IL41747 and IL42218) and the sequence analyses indicated that IL42218 was a reassortant between different serotypes whereas IL41747 was a genetically stable strain. Our data suggest that multiple strains contribute to outbreaks each year.  相似文献   
78.
79.
80.

Background Context

Low back pain (LBP) is a common complaint in clinical practice of multifactorial origin. Although obesity has been thought to contribute to LBP primarily by altering the distribution of mechanical loads on the spine, the additional contribution of obesity-related conditions such as diabetes mellitus (DM) to LBP has not been thoroughly examined.

Purpose

To determine if there is a relationship between DM and LBP that is independent of body mass index (BMI) in a large cohort of adult survey participants.

Study Design

Retrospective analysis of prospectively collected National Health and Nutrition Examination Survey (NHANES) data to characterize associations between LBP, DM, and BMI in adults subdivided into 6 subpopulations: normal weight (BMI 18.5–25), overweight (BMI 25–30), and obese (BMI >30) diabetics and nondiabetics. Diabetes was defined with glycohemoglobin A1c (HbA1c) 6.5%.

Patient Sample

11,756 participants from NHANES cohort.

Outcome Measures

Percentage of LBP reported.

Methods

LBP reported in the 1999-2004 miscellaneous pain NHANES questionnaire was the dependent variable examined. Covariates included HbA1c, BMI, age, and family income ratio to poverty as continuous variables as well as race, gender, and smoking as binary variables. Individuals were further subdivided by weight class and diabetes status. Regression and graphical analyses were performed on the study population as a whole and also on subpopulations.

Results

Increasing HbA1c did not increase the odds of reporting LBP in the full cohort. However, multivariate logistic regression of the 6 subpopulations revealed that the odds of LBP significantly increased with increasing HbA1c levels in normal weight diabetics. No other subpopulations reported significant relationships between LBP and HbA1c. LBP was also significantly associated with BMI for normal weight diabetics and also for obese subjects regardless of their DM status.

Conclusions

LBP is significantly related to DM status, but this relationship is complex and may interact with BMI. These results support the concept that LBP may be improved in normal weight diabetic subjects with improved glycemic control and weight loss, and that all obese LBP subjects may benefit from improved weight loss alone.  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