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   49569篇
  免费   4009篇
  国内免费   133篇
耳鼻咽喉   617篇
儿科学   1292篇
妇产科学   1123篇
基础医学   6641篇
口腔科学   947篇
临床医学   5663篇
内科学   9812篇
皮肤病学   502篇
神经病学   4097篇
特种医学   1651篇
外科学   7896篇
综合类   797篇
现状与发展   1篇
一般理论   38篇
预防医学   4753篇
眼科学   824篇
药学   3377篇
中国医学   78篇
肿瘤学   3602篇
  2023年   324篇
  2022年   425篇
  2021年   1330篇
  2020年   720篇
  2019年   1159篇
  2018年   1313篇
  2017年   938篇
  2016年   948篇
  2015年   1103篇
  2014年   1509篇
  2013年   2029篇
  2012年   3145篇
  2011年   3160篇
  2010年   1701篇
  2009年   1485篇
  2008年   2606篇
  2007年   2664篇
  2006年   2396篇
  2005年   2336篇
  2004年   2310篇
  2003年   2130篇
  2002年   2066篇
  2001年   1045篇
  2000年   1006篇
  1999年   932篇
  1998年   601篇
  1997年   532篇
  1996年   474篇
  1995年   461篇
  1994年   368篇
  1993年   311篇
  1992年   713篇
  1991年   593篇
  1990年   601篇
  1989年   556篇
  1988年   547篇
  1987年   517篇
  1986年   539篇
  1985年   516篇
  1984年   453篇
  1983年   379篇
  1982年   293篇
  1981年   272篇
  1980年   294篇
  1979年   395篇
  1978年   291篇
  1977年   266篇
  1974年   261篇
  1973年   238篇
  1972年   225篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
This paper reviews the published literature on a group of developmental disorders of the retina and retinal pigment epithelium which result in focal abnormalities in one or both eyes. They are often asymptomatic, found on routine examination and are generally non-progressive. Some are associated with other systemic abnormalities.Subject terms: Retinal diseases, Eye abnormalities  相似文献   
22.
2‐deoxy D‐glucose (2DG) was tested for efficacy in treating alopecia areata using the C3H/HeJ skin graft model. 2DG has proven to be efficacious in treatment of various mouse models of autoimmunity with minimal serious side effects noted. This agent has been shown to normalize abnormally activated T‐cell populations while also preventing cell surface expression of NKG2D; key factors defining alopecia areata disease progression. Daily oral ingestion of 2DG via drinking water to mice with patchy or diffuse alopecia areata for 16 weeks failed to prevent expansion of alopecia or cause regrowth of hair in treated mice. Histologically, there were no differences between treated and control groups. These results indicate that, while 2DG is effective for some autoimmune diseases, it was not efficacious for the cell‐mediated autoimmune mouse disease, alopecia areata.  相似文献   
23.
24.

Background

Most elderly trauma patients suffer blunt head injury and many utilize antithrombotic (AT) medications. The utility of delayed CT-head (D-CTH) in neurologically intact elderly patients using AT who have an intracranial hemorrhage (ICH) on presentation is unknown. We hypothesized that D-CTH would not alter clinical management and aimed to evaluate the role of D-CTH in this population.

Methods

A retrospective cohort study was performed. Patients ≥65 years sustaining blunt head injuries from January 2010 to July 2017 were identified using our level 1 trauma center database. AT-patients presenting with ICH who underwent D-CTH were included. Patients with worsened ICH were compared to those with stable to improved ICH on D-CTH. AT-patients were compared to a cohort of non-AT patients. Fisher’s Exact and Mann-Whitney U tests were utilized and a power analysis conducted.

Results

137?A?T and 34 non-AT patients were identified. There was no difference in hemorrhage progression or appearance of new ICH. No patient had a change in management from D-CTH in either cohort. AT-patients were slightly older (p?<?0.001), but cohorts were otherwise similar.50 AT-patients with worsened ICH were compared to 87 with stable ICH. There was no difference in cohort demographics. Hemorrhage progression did not vary with type of AT used but did increase if multiple types of synchronous ICH were present (p?<?0.001).

Conclusions

Our data supports abstaining from routine D-CTH of elderly ICH patients with an intact neurologic examination who are utilizing aspirin, clopidogrel or warfarin. Conclusions cannot be drawn regarding new oral anticoagulants (NOACs) given low enrollment. Further multicenter study is required to provide adequate power and detect small levels of management change.  相似文献   
25.
<正>Microvascular dysfunction and rheumatoid arthritis(RA):Across the UK severe osteoarthritis affects~5–7%and RA affects~1%of the population.These are the most common causes of disabling chronic pain and are major burdens on individuals and society.Consequently,the annual financial cost to the UK economy for arthritis is in the billions of pounds.People living with painful inflammatory conditions and in  相似文献   
26.
We consider the scenario where there is an exposure, multiple biologically defined sets of biomarkers, and an outcome. We propose a new two-step procedure that tests if any of the sets of biomarkers mediate the exposure/outcome relationship, while maintaining a prespecified familywise error rate. The first step of the proposed procedure is a screening step that removes all groups that are unlikely to be strongly associated with both the exposure and the outcome. The second step adapts recent advances in postselection inference to test if there are true mediators in each of the remaining candidate sets. We use simulation to show that this simple two-step procedure has higher statistical power to detect true mediating sets when compared with existing procedures. We then use our two-step procedure to identify a set of Lysine-related metabolites that potentially mediate the known relationship between increased body mass index and the increased risk of estrogen-receptor positive breast cancer in postmenopausal women.  相似文献   
27.
Abstract

The purpose of this study was to investigate the strength of the relationships between self-efficacy and (i) functional exercise capacity and (ii) physical activity in chronic obstructive pulmonary disease (COPD), and whether self-efficacy assessment type (i.e., COPD symptoms, exercise-task, exercise-barrier, general, falls) and physical activity assessment type (i.e., self-report vs. objective) are moderators. A systematic search of COPD and self-efficacy concepts was conducted using eight databases from inception to 23 January 2019. Studies were included if they provided correlation coefficients of the relationship between self-efficacy and functional exercise capacity or physical activity, were conducted in adults diagnosed with COPD, and were published in English-language journals. A total of 14 correlation coefficients were included in the self-efficacy and functional exercise capacity meta-analysis, and 16 in the self-efficacy and physical activity meta-analysis. Data were screened, reviewed, and extracted independently by two reviewers, with discrepancies resolved by a third reviewer. Stronger self-efficacy was associated with better functional exercise capacity (weighted r?=?0.38, 95%CI [0.25, 0.50]), and greater physical activity (weighted r?=?0.25, 95%CI [0.17, 0.34]). Exercise-task self-efficacy had the strongest relationship to functional exercise capacity (weighted r?=?0.64, 95% CI [0.51, 0.73]). For physical activity, the type of self-efficacy most strongly related was inconclusive. In COPD, self-efficacy has a relationship to functional exercise capacity and physical activity, the strength of which is influenced by the choice of self-efficacy measure. An understanding of these relationships will assist clinicians in selecting the self-efficacy measure most closely related to the outcome of interest.  相似文献   
28.
29.
30.

Purpose

To quantify eating disorder (ED) stability and diagnostic transition among a community-based sample of adolescents and young adult females in the United States.

Methods

Using 11 prospective assessments from 9,031 U.S. females ages 9–15 years at baseline of the Growing Up Today Study, we classified cases of the following EDs involving bingeing and purging: bulimia nervosa (BN), binge ED, purging disorder (PD), and subthreshold variants defined by less frequent (monthly vs. weekly) bingeing and purging behaviors. We measured number of years symptomatic and probability of maintaining symptoms, crossing to another diagnosis, or resolving symptoms across consecutive surveys.

Results

Study lifetime disorder prevalence was 2.1% for BN and roughly 6% each for binge ED and PD. Most cases reported symptoms during only one survey year. Twenty-six percent of cases crossed between diagnoses during follow-up. Among participants meeting full threshold diagnostic criteria, transition from BN was most prevalent, crossing most frequently from BN to PD (12.9% of BN cases). Within each disorder phenotype, 20%–40% of cases moved between subthreshold and full threshold criteria across consecutive surveys.

Conclusions

Diagnostic crossover is not rare among adolescent and young adult females with an ED. Transition patterns from BN to PD add support for considering these classifications in the same diagnostic category of disorders that involve purging. The prevalence of crossover between monthly and weekly symptom frequency suggests that a continuum or staging approach may increase utility of ED classification for prognostic and therapeutic intervention.  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