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   204152篇
  免费   22979篇
  国内免费   2611篇
耳鼻咽喉   5590篇
儿科学   6551篇
妇产科学   3557篇
基础医学   8787篇
口腔科学   2387篇
临床医学   30886篇
内科学   56679篇
皮肤病学   8225篇
神经病学   19454篇
特种医学   7734篇
外科学   46307篇
综合类   401篇
现状与发展   72篇
一般理论   19篇
预防医学   10180篇
眼科学   4079篇
药学   3631篇
  6篇
中国医学   91篇
肿瘤学   15106篇
  2024年   926篇
  2023年   5554篇
  2022年   2415篇
  2021年   4827篇
  2020年   7035篇
  2019年   3623篇
  2018年   8970篇
  2017年   8393篇
  2016年   9584篇
  2015年   9796篇
  2014年   17372篇
  2013年   18001篇
  2012年   9183篇
  2011年   9169篇
  2010年   12139篇
  2009年   15871篇
  2008年   8702篇
  2007年   6845篇
  2006年   9022篇
  2005年   6285篇
  2004年   5132篇
  2003年   3878篇
  2002年   3744篇
  2001年   3974篇
  2000年   3127篇
  1999年   3399篇
  1998年   3902篇
  1997年   3658篇
  1996年   3536篇
  1995年   3360篇
  1994年   2076篇
  1993年   1673篇
  1992年   1444篇
  1991年   1472篇
  1990年   1109篇
  1989年   1211篇
  1988年   1044篇
  1987年   881篇
  1986年   910篇
  1985年   743篇
  1984年   580篇
  1983年   537篇
  1982年   548篇
  1981年   422篇
  1980年   379篇
  1979年   315篇
  1978年   339篇
  1977年   408篇
  1975年   283篇
  1972年   309篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
12.
Veterans are at an increased risk of being injured or killed in motor vehicle crashes, potentially due to their proclivity to engage in risky driving behaviors. However, most research in this area has focused on driving behaviors of veterans who have recently returned home after deployment. No research has focused on risky driving behaviors of older veterans (aged 65 or older) and if risky driving behaviors extend beyond the time period immediately following return from deployment. The purpose of this research is to determine if differences exist in risky driving behaviors of veterans and non-veterans aged 65 or older. This study used data from the 2011 National Health and Aging Trend Study (NHATS), a nationally representative, longitudinal survey of community-dwelling, Medicare beneficiaries aged 65 or older. Binary logistic regression analyses were conducted in 2017 to determine if veteran’s status was predictive of specific risky driving behaviors. Veteran’s status was found to be predictive of specific driving behaviors for adults aged 65 and older, with non-veterans significantly more likely than veterans to: not currently drive; avoid driving at night; avoid driving alone; avoid driving on busy roads or highways; and avoid driving in bad weather. The results of this study highlight the need to further understand the effects of veteran’s status on risky driving behaviors among older adults, specifically, whether veteran’s status compounds driving-related risks associated with aging-related physical and mental changes.  相似文献   
13.
Patients undergoing high-dose chemotherapy and autologous hematopoietic cell transplantation (auto-HCT) are at risk for multiple morbidities, including mucosal inflammation and neutropenic fever, both related to neutropenia. Evidence from our preclinical work in an umbilical cord blood (UCB) transplantation murine model suggests that treatment with hyperbaric oxygen (HBO) before UCB infusion improves UCB CD34+ cell engraftment by reducing erythropoietin levels. A pilot clinical trial using HBO in patients undergoing UCB transplantation showed improvement in kinetics of blood count recovery. In this study, we evaluated HBO in combination with auto-HCT. Our primary aim was to determine the safety of HBO in this setting and secondarily to determine its efficacy in reducing time to neutrophil and platelet engraftment compared with matched historic controls. Patients with multiple myeloma, non-Hodgkin lymphoma, and Hodgkin disease eligible for auto-HCT were included. On day 0, patients received HBO treatment consisting of exposure to 2.5 atmosphere absolutes for a total of 90 minutes, in a monoplace hyperbaric chamber, breathing 100% oxygen. Six hours after the start of HBO, peripherally mobilized stem/progenitor cells were infused and patients were followed daily for toxicity and blood count recovery. All patients received daily granulocyte colony-stimulating factor starting on day +5 and until absolute neutrophil count (ANC) of ≥1500 or ANC of 500 for 3 consecutive days. A matched historic cohort of 225 patients who received auto-HCT between January 2008 and December 2012 was chosen for comparison and matched on sex, age, conditioning regimen, and disease type. We screened 26 patients for this study; 20 were treated and included in the primary analysis, and 19 completed the HBO therapy and were included in the secondary analysis. Although the median time to neutrophil count recovery was 11 days in both the HBO and control cohorts, the Kaplan-Meier estimates of the full distributions indicate that the time to neutrophil recovery was generally about 1 day sooner for HBO versus historical controls (log-rank P = .005; range, 9 to 13 for HBO patients and 7 to 18 for controls). The median time to platelet count recovery was 16 days (range, 14 to 21) for HBO versus 18 days (range, 11 to 86) for controls (log-rank P < .0001). In the secondary analysis comparing the HBO cohort who completed HBO therapy (n = 19) with our historical cohort, we evaluated neutropenic fever, growth factor use, mucositis, day +100 disease responses, and blood product use. HBO was associated with less growth factor use (median 6 days in HBO cohort versus median 8 days in controls, P < .0001). Packed RBC and platelet transfusion requirements were not statistically different between the 2 cohorts. Mucositis incidence was significantly lower in the HBO cohort (26.3% in HBO cohort versus 64.2% in controls, P = .002). HBO therapy appears to be well tolerated in the setting of high-dose therapy and auto-HCT. Prospective studies are needed to confirm potential benefits of HBO with respect to earlier blood count recovery, reduced mucositis, and growth factor use, and a cost-benefit analysis is warranted.© 2019 American Society for Blood and Marrow Transplantation.  相似文献   
14.
15.
16.
17.
18.
19.
20.
PURPOSE: The aim of the study was to clinically evaluate Empress II inlays cemented with a dual-curing bonding agent and a self-curing luting system. MATERIALS AND METHODS: Forty patients were selected to receive one Empress II inlay. Empress II is a heat-pressed glass ceramic containing lithium disilicate and lithium orthophosphate crystals, purported to provide higher stress resistance and improved strength. The restorations were placed between March and May 2000. Recalls were performed after 6, 12, 24, and 36 months. At the 3-year recall, 7 patients were lost to follow-up. Inlays were evaluated for postoperative sensitivity, marginal integrity, marginal leakage, color stability, surface staining, retention, and surface crazing (microcracks). RESULTS: At the 3-year recall, all the restorations were in place and only one showed postoperative sensitivity (at the first recall, 1 week after placement). Only 3 inlays showed slight marginal staining, and 4 inlays showed gaps, with little surface staining or microcracks. CONCLUSIONS: No inlay debonded or fractured during theobservation period. All the evaluated inlays were in place and acceptable.  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