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   166240篇
  免费   3670篇
  国内免费   1679篇
耳鼻咽喉   1658篇
儿科学   6148篇
妇产科学   2686篇
基础医学   20102篇
口腔科学   4206篇
临床医学   10913篇
内科学   32025篇
皮肤病学   2975篇
神经病学   10157篇
特种医学   3431篇
外国民族医学   3篇
外科学   26107篇
综合类   9602篇
现状与发展   1篇
一般理论   4篇
预防医学   8611篇
眼科学   3270篇
药学   17981篇
  9篇
中国医学   6265篇
肿瘤学   5435篇
  2022年   882篇
  2021年   2230篇
  2020年   1092篇
  2019年   12765篇
  2018年   12526篇
  2017年   5509篇
  2016年   1092篇
  2015年   1107篇
  2014年   2627篇
  2013年   4404篇
  2012年   2756篇
  2011年   2832篇
  2010年   2389篇
  2009年   2386篇
  2008年   2795篇
  2007年   3892篇
  2006年   4145篇
  2005年   4064篇
  2004年   3202篇
  2003年   3250篇
  2002年   3173篇
  2001年   3166篇
  2000年   3406篇
  1999年   3064篇
  1998年   3112篇
  1997年   2486篇
  1996年   2321篇
  1995年   2652篇
  1994年   2480篇
  1993年   1932篇
  1992年   1516篇
  1991年   1500篇
  1990年   1251篇
  1989年   993篇
  1988年   1024篇
  1987年   989篇
  1986年   835篇
  1985年   5411篇
  1984年   7287篇
  1983年   5825篇
  1982年   6269篇
  1981年   5719篇
  1980年   4919篇
  1979年   4969篇
  1978年   4063篇
  1977年   3051篇
  1976年   3524篇
  1975年   2738篇
  1974年   2524篇
  1973年   2226篇
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
61.
62.

Background

The purpose of the study was to evaluate the association between fetal echocardiographic measurements and the need for intervention (primary coarctation repair, staged coarctation repair, or catheter intervention) in prenatally diagnosed coarctation of the aorta.

Methods

A single-centre retrospective cohort study (2005-2015) of 107 fetuses diagnosed with suspected coarctation of the aorta in the setting of an apex-forming left ventricle and antegrade flow across the mitral and aortic valves.

Results

Median gestational age at diagnosis was 32 weeks (interquartile range, 23-35 weeks). Fifty-six (52%) did not require any neonatal intervention, 51 patients (48%) underwent a biventricular repair. In univariable analysis, an increase in ascending aorta (AAo) peak Doppler flow velocity (odds ratio [OR], 1.40 [95% confidence interval [CI], 1.05-1.91] per 20 cm/s; P = 0.03) was associated with intervention. No intervention was associated with larger isthmus size (OR, 0.23; P < 0.001), transverse arch diameter (OR, 0.23; P < 0.001), and aortic (OR, 0.72; P = 0.02), mitral (OR, 0.58; P = 0.001), and AAo (OR, 0.53; P < 0.001) z-scores. In multivariable analysis, higher peak AAo Doppler (OR, 2.51 [95% CI, 1.54-4.58] per 20 cm/s; P = 0.001) and younger gestational age at diagnosis (OR, 0.81 [95% CI, 0.70-0.93] per week; P = 0.005) were associated with intervention, whereas a higher AAo z-score (OR, 0.65 [95% CI, 0.43-0.94] per z; P = 0.029) and transverse arch dimension (OR, 0.44 [95% CI, 0.18-0.97]; P = 0.05) decreased the risk of intervention.

Conclusions

In prenatally suspected coarctation, the variables associated with intervention comprised smaller AAo and transverse arch size, earlier gestational age at diagnosis, and the additional finding of a higher peak AAo Doppler.  相似文献   
63.
64.

Purpose

A hydrogel rectal spacer (HRS) is a medical device that is approved by the U.S. Food and Drug Administration to increase the separation between the prostate and rectum. We conducted a cost-effectiveness analysis of HRS use for reduction in radiation therapy (RT) toxicities in patients with prostate cancer (PC) undergoing external beam RT (EBRT).

Methods and Materials

A multistate Markov model was constructed from the U.S. payer perspective to examine the cost-effectiveness of HRS in men with localized PC receiving EBRT (EBRT alone vs EBRT + HRS). The subgroups analyzed included site of HRS placement (hospital outpatient, physician office, ambulatory surgery center) and proportion of patients with good baseline erectile function (EF). Data on EF, gastrointestinal and genitourinary toxicities incidence, and potential risks associated with HRS implantation were obtained from a recently published randomized clinical trial. Health utilities and costs were derived from the literature and the 2018 Physician Fee Schedule and were discounted 3% annually. Quality-adjusted life years (QALYs) and costs were modeled for a 5-year period from receipt of RT. Probabilistic sensitivity analysis and value-based threshold analyses were conducted.

Results

The per-patient 5-year incremental cost for spacers administered in a hospital outpatient setting was $3578, and the incremental effectiveness was 0.0371 QALYs. The incremental cost-effectiveness ratio was $96,440/QALY for patients with PC undergoing HRS insertion in a hospital and $39,286/QALY for patients undergoing HRS insertion in an ambulatory facility. For men with good baseline EF, the incremental cost-effectiveness ratio was $35,548/QALY and $9627/QALY in hospital outpatient and ambulatory facility settings, respectively.

Conclusions

Based on the current Medicare Physician Fee Schedule, HRS is cost-effective at a willingness to pay threshold of $100,000. These results contain substantial uncertainty, suggesting more evidence is needed to refine future decision-making.  相似文献   
65.
66.
67.
68.
69.
70.
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