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   24764篇
  免费   6910篇
  国内免费   86篇
耳鼻咽喉   408篇
儿科学   783篇
妇产科学   606篇
基础医学   1295篇
口腔科学   1593篇
临床医学   7227篇
内科学   5290篇
皮肤病学   632篇
神经病学   3141篇
特种医学   698篇
外国民族医学   3篇
外科学   3042篇
综合类   147篇
现状与发展   2篇
一般理论   13篇
预防医学   3640篇
眼科学   475篇
药学   826篇
中国医学   26篇
肿瘤学   1913篇
  2024年   150篇
  2023年   1345篇
  2022年   398篇
  2021年   908篇
  2020年   1258篇
  2019年   707篇
  2018年   1700篇
  2017年   1804篇
  2016年   1774篇
  2015年   1816篇
  2014年   2161篇
  2013年   2231篇
  2012年   1232篇
  2011年   1250篇
  2010年   1336篇
  2009年   1696篇
  2008年   942篇
  2007年   799篇
  2006年   923篇
  2005年   725篇
  2004年   596篇
  2003年   522篇
  2002年   421篇
  2001年   436篇
  2000年   284篇
  1999年   353篇
  1998年   344篇
  1997年   347篇
  1996年   318篇
  1995年   292篇
  1994年   184篇
  1993年   175篇
  1992年   205篇
  1991年   176篇
  1990年   138篇
  1989年   173篇
  1988年   143篇
  1987年   134篇
  1986年   128篇
  1985年   121篇
  1984年   80篇
  1983年   68篇
  1982年   61篇
  1980年   54篇
  1979年   70篇
  1978年   58篇
  1977年   72篇
  1976年   50篇
  1972年   50篇
  1970年   54篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Farming is an occupation that blends the work and home environments and traditionally involves active participation of all family members, including older farmers. The work patterns of older farmers, including typical work hours, range of activities, and health status, are not well documented. This study, surveying a random sample of older Illinois farmers (N=87), focused on these gaps in the literature. Older farmers were found to work long hours in many farm tasks, more than would be expected in other occupational groups. Further, older farmers were found to have several chronic diseases at higher rates than the general population of the same age and gender; mental health implications were also identified. Rural occupational health nurses are in an optimal position to positively impact older farmers' mental and physical health status.  相似文献   
62.
Objectives: In this study, the authors tested whether electromagnetic interference (EMI) is able to impair correct electrocardiogram analysis and produce false‐positive shock advice from automated external defibrillators (AEDs) when the true rhythm is sinus. Methods: Nineteen healthy subjects were used to test five AEDs available on the Austrian market in a prospective, open, and sequence‐randomized study. The primary outcome variable was the absolute number of shocks advised in the presence of EMI. The secondary outcome was the number of impaired analyses caused by incorrectly detected patient movements or electrode failure. Results: Of 760 tests run, 18 (2.37%) cases of false‐positive results occurred, and two of five AEDs recommended shocks in the presence of sinus rhythm. Of 760 tests run, no electrode failures occurred. There were 27 occurrences (3.55%) of motion detected by an AED in the presence of strong electromagnetic fields. Conclusions: AED models differ in their response to EMI; it may be useful to consider specific safety requirements for areas with such fields present. Working personnel and emergency medical services staff should be informed about potential risks and the possible need for patient evacuation before AEDs are attached and shock recommendations are followed.  相似文献   
63.
64.
The World Wide Web creates new challenges and opportunities for medical educators. Prominent among these are the lack of consistent standards by which to evaluate web-based educational tools. We present the instrument that was used to review web-based innovations in medical education submissions to the 2003 Society of General Internal Medicine (SGIM) national meeting, and discuss the process used by the SGIM web-based clinical curriculum interest group to develop the instrument. The 5 highest-ranked submissions are summarized with commentary from the reviewers.  相似文献   
65.
This breakout session at the Academic Emergency Medicine 2006 Consensus Conference examined how baseline overcrowding impedes the ability of emergency departments to respond to sudden, unexpected surges in demand for patient care. Differences between daily and catastrophic surge were discussed, and the need to invoke a hospital-wide response to surge was explored.  相似文献   
66.
67.
Background: Elder patients with acute coronary syndromes (ACS) are less likely to receive cardiac catheterization. The reasons for this are unclear.
Objectives: To assess whether elder patients who had a documented history of dementia, lived in extended care facilities, or had do not intubate–do not resuscitate (DNR-DNI) advance directives were less likely to receive cardiac catheterization, despite having ACS with high-risk features.
Methods: This was a medical record review conducted at an urban teaching hospital. DNR-DNI status before hospitalization, extended care facility (nursing home or assisted living) residence, and a previous diagnosis of dementia were obtained from the medical record. Patients 65 years and older who presented to the emergency department with acute myocardial infarction or with unstable angina with ST segment deviation were included. Univariate and multivariate logistic regression were performed, and odds ratios (ORs) were reported with their 95% confidence intervals (CIs).
Results: Of the 201 eligible patients, 66 (32.8%) patients did not undergo cardiac catheterization. In the univariate analysis, patients who had dementia, resided in extended care facilities, or were DNR-DNI were less likely to receive cardiac catheterization. Only extended care facility residence (OR, 0.18; 95% CI = 0.04 to 0.83) and DNR-DNI status (OR, 0.19; 95% CI = 0.04 to 0.92) remained significantly associated with decreased cardiac catheterization in the multivariate analysis.
Conclusions: Elder patients with ACS residing in extended care facilities or who are DNR-DNI are less likely to receive cardiac catheterization. Future studies concerning the quality of ACS care for elders should take these variables into account.  相似文献   
68.
Previous observations have suggested that differentiated functions of adult rat type II alveolar cells are affected in part by cell-matrix interactions. We examined several aspects of differentiated adult human type II cells cultured on either bovine corneal endothelial cell extracellular matrix (BCECM) or matrix derived from the Englebreth-Holm-Swarm tumor (EHS). Compared to cells cultured on BCECM, adult human type II cells grown on EHS assumed a more cuboidal shape, had a more defined apical-basal polarity, and appeared to contain a greater number of lamellar bodies and neutral lipid inclusions. These cells also incorporated a greater percentage of [14C]acetate into saturated phosphatidylcholine (SPC) than did their counterparts grown on BCECM. In contrast, the relative incorporation of [14C]acetate into phosphatidylglycerol (PG) was lower in cells grown on EHS than cells cultured on BCECM. The histochemical stain for alkaline phosphatase was useful in identification of human type II cells. Alkaline phosphatase expression was elevated in cells cultured on EHS compared to those cultured on BCECM. These results suggest that maintenance of a differentiated morphology, lipid synthesis, and expression of alkaline phosphatase activity by primary cultures of adult human type II cells are also influenced by cell-matrix interactions. All markers of differentiated function of type II cells except synthesis of PG are better maintained on EHS than on BCECM. Under the conditions of these experiments, synthesis of SPC and PG appears to be independently regulated.  相似文献   
69.
Aspects of humoral and cell-mediated immunity that might characterize the continuation of symptoms in 25 patients with chronic Meniere's disease were examined. We found significant elevations of both humoral and cellular immune responses to viral antigens of herpes simplex I, varicella-zoster, rubella, and cytomegalovirus. Serum immunoglobulins were quantitatively abnormal in 24 of 25 patients, without a consistent pattern. These immune responses may be linked to persistent viral infection in chronic Meniere's disease.  相似文献   
70.
The short-term albumin affinity and thrombo-resistance of a polyether polyurethane vascular graft have been improved. The method is based on the C18 alkylation of the polymer. Thrombus formation by a planimetric technique and albumin retention on wire-reinforced polyurethane tubes, both C18 alkylated and untreated, were measured in short-term (4-h) exposure at femoral arterial sites in the dog. 125I-Albumin was preabsorbed on tubes and then exposed to blood for successive 2-h periods. Albumin uptake on alkylated tubes prior to blood exposure and retention following 2 h of blood exposure were significantly greater than on controls. Following a fast desorption phase in blood, the remaining albumin was more slowly desorbed from alkylated than from control tubes. Reincubation with albumin and blood reexposure produced a similar tendency, suggesting blood conditioning does not reduce the albumin affinity-enhancing property of C18 alkylation in the short term. Blood-preconditioning experiments suggested endogenous albumin has a high affinity for the C18-alkylated surface. Scanning electron microscopic examination showed thrombus and platelet densities were higher on control than on alkylated surfaces. These results suggest in vivo albumin affinity is increased for C18-alkylated polyurethane, which may be linked to decreased thrombus formation on these surfaces.  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