收费全文 | 6184篇 |
免费 | 509篇 |
国内免费 | 9篇 |
耳鼻咽喉 | 112篇 |
儿科学 | 270篇 |
妇产科学 | 151篇 |
基础医学 | 723篇 |
口腔科学 | 82篇 |
临床医学 | 657篇 |
内科学 | 1131篇 |
皮肤病学 | 70篇 |
神经病学 | 548篇 |
特种医学 | 336篇 |
外科学 | 857篇 |
综合类 | 84篇 |
一般理论 | 10篇 |
预防医学 | 648篇 |
眼科学 | 112篇 |
药学 | 345篇 |
中国医学 | 9篇 |
肿瘤学 | 557篇 |
2022年 | 49篇 |
2021年 | 150篇 |
2020年 | 80篇 |
2019年 | 142篇 |
2018年 | 131篇 |
2017年 | 102篇 |
2016年 | 81篇 |
2015年 | 106篇 |
2014年 | 176篇 |
2013年 | 218篇 |
2012年 | 329篇 |
2011年 | 340篇 |
2010年 | 175篇 |
2009年 | 164篇 |
2008年 | 287篇 |
2007年 | 288篇 |
2006年 | 284篇 |
2005年 | 309篇 |
2004年 | 276篇 |
2003年 | 238篇 |
2002年 | 229篇 |
2001年 | 181篇 |
2000年 | 168篇 |
1999年 | 151篇 |
1998年 | 62篇 |
1997年 | 60篇 |
1996年 | 53篇 |
1995年 | 54篇 |
1994年 | 50篇 |
1993年 | 53篇 |
1992年 | 125篇 |
1991年 | 112篇 |
1990年 | 119篇 |
1989年 | 147篇 |
1988年 | 123篇 |
1987年 | 120篇 |
1986年 | 104篇 |
1985年 | 97篇 |
1984年 | 80篇 |
1983年 | 62篇 |
1982年 | 37篇 |
1981年 | 39篇 |
1980年 | 32篇 |
1979年 | 57篇 |
1978年 | 38篇 |
1977年 | 33篇 |
1976年 | 37篇 |
1974年 | 34篇 |
1973年 | 32篇 |
1972年 | 39篇 |
Objectives
Expedient extubation after cardiac surgery has been associated with improved outcomes, leading to postoperative extubation frequently during overnight hours. However, recent evidence in a mixed medical-surgical intensive care unit population demonstrated worse outcomes with overnight extubation. This study investigated the impact of overnight extubation in a statewide, multicenter Society of Thoracic Surgeons database.Methods
Records from 39,812 patients undergoing coronary artery bypass grafting or valve operations (2008-2016) and extubated within 24 hours were stratified according to extubation time between 06:00 and 18:00 (day) or between 18:00 and 6:00 (overnight). Outcomes including reintubation, mortality, and composite morbidity-mortality were evaluated using hierarchical regression models adjusted for Society of Thoracic Surgeons predictive risk scores. To further analyze extubation during the night, a subanalysis stratified patients into 3 groups: 06:00 to 18:00, 18:00 to 24:00, and 24:00 to 06:00.Results
A total of 20,758 patients were extubated overnight (52.1%) and were slightly older (median age 66 vs 65 years, P < .001) with a longer duration of ventilation (4 vs 7 hours, P < .001). Day and overnight extubation were associated with equivalent operative mortality (1.7% vs 1.7%, P = .880), reintubation (3.7% vs 3.4%, P = .141), and composite morbidity-mortality (8.2% vs 8.0%, P = .314). After risk adjustment, overnight extubation was not associated with any difference in reintubation, mortality, or composite morbidity-mortality. On subanalysis, those extubated between 24:00 and 06:00 exhibited increased composite morbidity-mortality (odds ratio, 1.18; P = .001) but no difference in reintubation or mortality.Conclusions
Extubation overnight was not associated with increased mortality or reintubation. These results suggest that in the appropriate clinical setting, it is safe to routinely extubate cardiac surgery patients overnight. 相似文献![点击此处可从《Pediatric dermatology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Objective
This study assessed whether immediate postpartum insertion of levonorgestrel contraceptive implants is associated with a difference in infant growth from birth to 6 months, onset of lactogenesis, or breastfeeding continuation at 3 and 6 months postpartum compared to delayed insertion at 6 to 8 weeks postpartum.Study design
We conducted a randomized trial of women in Uganda who desired contraceptive implants postpartum. We randomly assigned participants to receive either immediate (within 5 days of delivery) or delayed (6 to 8 weeks postpartum) insertion of a two-rod levonorgestrel contraceptive implant system. This is a prespecified secondary analysis evaluating breastfeeding outcomes. The primary outcome of this secondary analysis was change in infant weight; infants were weighed and measured at birth and 6 months. We used a validated questionnaire to assess onset of lactogenesis daily in person while participants were in the hospital, and then daily by phone after they left the hospital, until lactogenesis was documented. We used interviewer-administered questionnaires to assess breastfeeding continuation and concerns at 3 months and 6 months postpartum.Results
Among the 96 women randomized to the immediate group and the 87 women to the delayed group, the mean change in infant weight from birth to 6 months was similar between groups: 4632?g in the immediate group and 4407?g in the delayed group (p=.26). Among the 97 women who had not experienced lactogenesis prior to randomization, the median time to onset of lactogenesis did not differ significantly between the immediate and delayed groups (65?h versus 63?h; p=.84). Similar proportions of women in the immediate and delayed groups reported exclusive breastfeeding at 3 months (74% versus 71%; p=.74) and 6 months (48% versus 52%; p=.58).Conclusion
We found no association between the timing of postpartum initiation of levonorgestrel contraceptive implants and change in infant growth from birth to 6 months, onset of lactogenesis, or breastfeeding continuation at 3 or 6 months postpartum.Implications
This study provides evidence that immediate postpartum initiation of contraception implants does not have a deleterious effect on infant growth or initiation or continuation of breastfeeding. 相似文献Objective: To quantify spatiotemporal and kinematic BW characteristics in post-stroke community ambulators and compare their performance to controls.
Methods: Individuals post-stroke (n = 15, 60.1 ± 12.9 years, forward speed: 1.13 ± 0.23 m/s) and healthy adults (n = 12, 61.2 ± 16.2 years, forward speed: 1.40 ± 0.13 m/s) performed forward walking (FW) and BW during a single session. Step characteristics and peak lower extremity joint angles were extracted using 3D motion analysis and analyzed with mixed-method ANOVAs (group, walking condition).
Results: The stroke group demonstrated greater reductions in speed, step length and cadence and a greater increase in double-support time during BW compared to FW (p < .01). Compared to FW, the post-stroke group demonstrated greater reductions in hip extension and knee flexion during BW (p < .05). The control group demonstrated decreased plantarflexion and increased dorsiflexion during BW, but these increases were attenuated in the post-stroke group (p < .05).
Conclusions: Assessment of BW can unmask post-stroke walking impairments not detected during typical FW. BW impairments may contribute to the mobility difficulties reported by adults post-stroke. Therefore, BW should be assessed when determining readiness for home and community ambulation. 相似文献