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   1645631篇
  免费   115899篇
  国内免费   4433篇
耳鼻咽喉   22607篇
儿科学   51188篇
妇产科学   45668篇
基础医学   239473篇
口腔科学   46250篇
临床医学   153895篇
内科学   311864篇
皮肤病学   32809篇
神经病学   135635篇
特种医学   61666篇
外国民族医学   430篇
外科学   236646篇
综合类   39625篇
现状与发展   3篇
一般理论   558篇
预防医学   136616篇
眼科学   37218篇
药学   121495篇
  42篇
中国医学   3602篇
肿瘤学   88673篇
  2018年   17753篇
  2017年   13539篇
  2016年   14855篇
  2015年   17029篇
  2014年   23892篇
  2013年   36731篇
  2012年   50191篇
  2011年   52892篇
  2010年   31073篇
  2009年   28513篇
  2008年   49049篇
  2007年   52245篇
  2006年   52185篇
  2005年   50784篇
  2004年   49044篇
  2003年   46858篇
  2002年   45162篇
  2001年   70296篇
  2000年   71977篇
  1999年   60866篇
  1998年   17881篇
  1997年   16275篇
  1996年   16079篇
  1995年   15162篇
  1994年   14408篇
  1993年   13435篇
  1992年   49742篇
  1991年   48753篇
  1990年   47478篇
  1989年   45349篇
  1988年   42350篇
  1987年   41285篇
  1986年   39449篇
  1985年   37817篇
  1984年   28847篇
  1983年   24742篇
  1982年   15338篇
  1981年   13724篇
  1979年   27762篇
  1978年   19746篇
  1977年   16502篇
  1976年   15756篇
  1975年   16521篇
  1974年   20397篇
  1973年   19892篇
  1972年   18590篇
  1971年   17361篇
  1970年   16188篇
  1969年   15221篇
  1968年   14129篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
ABSTRACT

Expeditious linkage and consistent engagement in medical care is important for people with HIV’s (PWH) health. One theory on fostering linkage and engagement involves HIV status disclosure to mobilize social support. To assess disclosure and social support’s association with linkage and engagement, we conducted a qualitative study sampling black and Latino men who have sex with men (MSM of color) in the U.S. Participants' narratives presented mixed results. For instance, several participants who reported delaying, inconsistent access, or detachment from care also reported disclosing for support purposes, yet sporadic engagement suggests that their disclosure or any subsequent social support have not assisted. The findings contribute to the literature that questions disclosure and social support’s influence on care engagement, especially when decontextualized from circumstances and intentions. Our findings suggest the mechanics of disclosure and social support require planned implementation if intending to affect outcomes, especially among MSM of color. From the findings, we explore steps that may bolster interventions seeking to anchor medical care engagement.  相似文献   
22.
23.

Objective

To compare perioperative and long-term outcomes in patients undergoing hemiarch and aggressive arch replacement for acute type A aortic dissection (ATAAD).

Methods

From 1996 to 2017, we compared outcomes of hemiarch (n = 322) versus aggressive arch replacements (zones 2 and 3 arch replacement with implantation of 2-4 arch branches, n = 150) in ATAAD. Indications for aggressive arch were arch aneurysm >4 cm or intimal tear in the aortic arch that was not resectable by hemiarch replacement, or dissection of arch branches with malperfusion.

Results

Patients in the aggressive arch group were significantly younger (mean age: 57 vs 61 years old) and had significantly longer hypothermic circulatory arrest, cardiopulmonary bypass, and aortic crossclamp times. There were no significant differences in perioperative outcomes between hemiarch and aggressive arch groups, including 30-day mortality (5.3% vs 7.3%, P = .38) and postoperative stroke rate (7% vs 7%, P = .96). Over 15 years, Kaplan–Meier survival was similar between hemiarch and aggressive arch groups (log-rank P = .55, 10-year survival 70% vs 72%). Given death as a competing factor, incidence rates of reoperation over 15 years (2.1% vs 2.0% per year, P = 1) and 10-year cumulative incidence of reoperation (14% vs 12%, P = .89) for arch and distal aorta pathology were similar between the 2 groups.

Conclusions

Both hemiarch and aggressive arch replacement are appropriate approaches for select patients with ATAAD. Aggressive arch replacement should be considered for an arch aneurysm >4 cm or an intimal tear at the arch unable to be resected by hemiarch replacement, or dissection of the arch branches with malperfusion.  相似文献   
24.
25.

Context

Demoralization is a state of existential distress in patients with advanced illness, typically with coping difficulties, feelings of loss of sense, and purpose in life and despair, among other things. The New Demoralization Scale (DS-II) is an evaluation tool for this syndrome, which has recently been reformulated on a shorter scale.

Objectives

The objective of this study was to obtain a Spanish version of the DS-II and to assess its psychometric properties in advanced cancer patients in Spain and a number of Latin American countries.

Methods

Following a translation–back translation process, a validation study and a confirmatory analysis using structural equation models with their corresponding latent constructs were undertaken. Patients completed the DS-II in Spanish (DS-II (es)), the Hospital Anxiety and Depression Scale, and the Edmonton Symptom Assessment System–revised. Reliability was studied according to internal consistency; construct validity and concurrent validity with the Hospital Anxiety and Depression Scale and the Edmonton Symptom Assessment System–revised; discriminant validity using the Karnofsky Performance Status scale; and feasibility, with response ratio and required time. Cutoff points were established, and sensitivity and specificity were studied.

Results

The DS-II (es) was obtained. One hundred fifty patients completed the validation study. The confirmatory analysis showed coherence, and all items correlated positively with their subscales and with the overall scale. Cronbach's alpha for the DS-II (es) was 0.88, for the sense and purpose subscale 0.83, and for the coping ability 0.79. Demoralization correlated significantly with emotional distress (rho = 0.73, P < 0.001). The tool distinguished between patients with diverse functional levels (rho = ?0.319, P = 0.001). Cutoff points at 10 and 20 out of 32 were established. The scale showed high sensitivity (81.97%) and specificity (80.90%). The prevalence of demoralization was 33% in our sample.

Conclusion

The Spanish version of the new Kissane DS-II demoralization scale has shown to be valid, reliable, and feasible with adequate psychometric properties.  相似文献   
26.

Context

Quality of life (QoL) is increasingly recognized as an important outcome of cancer treatment. Previous studies have examined clinical predictors of QoL, but with the increasing prevalence of wearable sensors that monitor sleep and activity patterns, further investigation into whether these behaviors are predictive of post-treatment QoL is now feasible. Among patients receiving aggressive cancer treatment such as hematopoietic cell transplantation (HCT), analysis of circadian rhythms (24-hour patterns of sleep and activity) via wearable sensors is limited.

Objective

To evaluate the relationship between overall QoL and circadian rhythms in patients receiving allogeneic HCT.

Methods

Patients wore an ActiGraph GT3X (Pensacola, FL) activity monitor for at least 72 hours before the initiation of conditioning chemotherapy and transplantation and completed a QoL (Functional Assessment of Cancer Therapy-General [FACT-G]) assessment. QoL assessments were also completed 1, 3, and 6 months after HCT.

Results

Patients (n = 45, M age = 55) were mostly male (66%) with a total FACT-G score of 80.96 (SD = 16.05) before HCT. Mixed models revealed robust cross-sectional associations between overall QoL and multiple circadian rhythmicity parameters, including durations of high physical activity, overall circadian rhythmicity, and earlier starts of daily activity (P's < .01). Recovery of QoL after transplant was predicted by longer pre-transplant durations of high physical activity (P = .04) and earlier evening retirement (P = .04).

Conclusion

Our findings suggest that wearable sensor information is a promising method of predicting recovery of QoL after HCT. Additional studies are needed to confirm these findings in a larger sample.  相似文献   
27.

Statement of problem

Polymeric material for 3-dimensional printing can be used to fabricate occlusal devices. However, information about fracture resistance and wear is scarce.

Purpose

The purpose of this in vitro study was to investigate the fracture resistance and 2-body wear of 3-dimensional–printed (3DP) (FotoDent splint; Dreve Dentamid GmbH), milled polymethylmethacrylate (CAM) (Temp Basic; Transpa 95H16, Zirkonzahn GmbH), and conventionally fabricated polymethylmethacrylate (CAST) (Castdon; Dreve Dentamid GmbH) occlusal devices.

Material and Methods

A total of 96 occlusal devices were prepared according to the 3 different manufacturing techniques 3DP, CAM, and CAST (n=32). For each manufacturing technique, specimens were further divided into initial fracture resistance tests (n=16) and artificial aging in the mastication simulator (50 N, 37°C) with 2-body wear followed by fracture resistance tests (n=16). The fracture resistance was determined using a universal testing machine (1 mm/min). The wear was measured after 20?000 and 120?000 mastication cycles with the replica technique, mapped with a laser scanner, and quantified in R software. Data were analyzed using a 2-way ANOVA followed by a 1-way ANOVA with Scheffé or Games-Howell post hoc tests, repeated measures ANOVA with corrected Greenhouse-Geisser P values, and the Levene, Mann-Whitney, and paired t tests (α=.05).

Results

CAM presented higher initial fracture resistance than 3DP or CAST (P<.001). After mastication simulation, CAM followed by 3DP showed higher fracture resistance than CAST (P<.001). Mastication simulation decreased the fracture resistance for CAM and CAST (P<.001) but not for 3DP (P=.78). Three-dimensional–printed occlusal devices showed the highest material volume loss, followed by CAM and the lowest in CAST (P<.001).

Conclusions

Three-dimensional–printed occlusal devices showed lower wear resistance and lower fracture resistance than those milled or conventionally fabricated. Therefore, only short-term application in the mouth is recommended. Further developments of occlusal device material for 3-dimensional printing are necessary.  相似文献   
28.

Background

Although some prior work supports the safety of same-day arthroplasty performed in a hospital, concerns remain when these procedures are performed in a free-standing ambulatory surgery center. The purpose of this study is to compare 90-day complication rates between matched cohorts that underwent inpatient vs outpatient arthroplasty at an ambulatory surgery center.

Methods

A single-surgeon cohort of 243 consecutive patients who underwent outpatient arthroplasty was matched with 243 inpatients who had the same procedure. One-to-one nearest-neighbor matching with respect to gender, age, American Society of Anesthesiologists Score, and body mass index was utilized. The 486 primary arthroplasties included 178 unicondylar knees (36.6%), 146 total hips (30.0%), 92 total knees (18.9%), and 70 hip resurfacings (14.5%). Ninety-day outcomes including reoperation, readmission, unplanned clinic or emergency department visits, and major and minor complications were compared using a 2-sample proportions test.

Results

The 2 cohorts were similar in distribution of demographic variables, demonstrating successful matching. The inpatient and outpatient cohorts both had readmission rates of 2.1% (P = 1.0). With the number of subjects studied, there were no statistically significant differences in rates of major complications (2.1% vs 2.5%, P = 1.0), minor complications (7.0% vs 7.8%, P = .86), reoperations (0.4% vs 2.1%, P = .22), emergency department visits (1.6% vs 2.5%, P = .52), or unplanned clinic visits (3.3% vs 5.8%, P = .19).

Conclusion

This study suggests that arthroplasty procedures can be performed safely in an ambulatory surgery center among appropriately selected patients without an increased risk of complications.  相似文献   
29.

Background

Endovascular aneurysm sealing (EVAS) represents a novel approach to the treatment of abdominal aortic aneurysms. It uses polymer technology to achieve an anatomic seal within the sac of the aneurysm. This cohort study reports the early clinical outcomes, technical refinements, and learning curve during the initial EVAS experience at a single institution.

Methods

Results from 150 consecutive EVAS cases for intact, infrarenal abdominal aortic aneurysms are reported here. These cases were undertaken between March 2013 and July 2015. Preoperative, perioperative, and postoperative data were collected for each patient prospectively.

Results

The median age of the cohort was 76.6 years (interquartile range, 70.2-80.9 years), and 87.3% were male. Median aneurysm diameter was 62.0 mm (IQR, 58.0-69.0 mm). Adverse neck morphology was seen in 69 (46.0%) patients, including aneurysm neck length <10 mm (17.3%), neck diameter >32 mm or <18 mm (8.7%), and neck angulation >60 degrees (15.3%). Median follow-up was 687 days (IQR, 463-897 days); 37 patients (24.7%) underwent reintervention. The rates of unresolved endoleak are 1.3% type IA, 0.7% type IB, and 2.7% type I. There were no type III endoleaks. There have been seven secondary ruptures in this cohort; all but one of these patients survived after reintervention. Only one rupture occurred in an aneurysm that had been treated within the manufacturer's instructions for use (IFU).

Conclusions

The rate of unresolved endoleaks is satisfactorily low. The incidence of secondary rupture is of concern; however, when the IFU are adhered to, the rate is very low. The results of this study suggest that working within the IFU yields better clinical results.  相似文献   
30.
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