全文获取类型
收费全文 | 17369篇 |
免费 | 1316篇 |
国内免费 | 23篇 |
专业分类
耳鼻咽喉 | 129篇 |
儿科学 | 812篇 |
妇产科学 | 466篇 |
基础医学 | 2329篇 |
口腔科学 | 187篇 |
临床医学 | 2435篇 |
内科学 | 3184篇 |
皮肤病学 | 255篇 |
神经病学 | 1519篇 |
特种医学 | 392篇 |
外国民族医学 | 1篇 |
外科学 | 1560篇 |
综合类 | 283篇 |
一般理论 | 17篇 |
预防医学 | 2449篇 |
眼科学 | 225篇 |
药学 | 1024篇 |
中国医学 | 13篇 |
肿瘤学 | 1428篇 |
出版年
2023年 | 107篇 |
2022年 | 142篇 |
2021年 | 352篇 |
2020年 | 283篇 |
2019年 | 441篇 |
2018年 | 439篇 |
2017年 | 362篇 |
2016年 | 397篇 |
2015年 | 384篇 |
2014年 | 542篇 |
2013年 | 870篇 |
2012年 | 1240篇 |
2011年 | 1344篇 |
2010年 | 720篇 |
2009年 | 682篇 |
2008年 | 1114篇 |
2007年 | 1176篇 |
2006年 | 1096篇 |
2005年 | 1108篇 |
2004年 | 972篇 |
2003年 | 854篇 |
2002年 | 839篇 |
2001年 | 271篇 |
2000年 | 236篇 |
1999年 | 237篇 |
1998年 | 152篇 |
1997年 | 123篇 |
1996年 | 114篇 |
1995年 | 130篇 |
1994年 | 101篇 |
1993年 | 91篇 |
1992年 | 141篇 |
1991年 | 148篇 |
1990年 | 106篇 |
1989年 | 134篇 |
1988年 | 105篇 |
1987年 | 107篇 |
1986年 | 115篇 |
1985年 | 104篇 |
1984年 | 84篇 |
1983年 | 78篇 |
1982年 | 53篇 |
1981年 | 50篇 |
1979年 | 51篇 |
1978年 | 43篇 |
1977年 | 32篇 |
1976年 | 34篇 |
1974年 | 31篇 |
1973年 | 38篇 |
1972年 | 55篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
991.
Press R Carrasquillo O Nickolas T Radhakrishnan J Shea S Barr RG 《Transplantation》2005,80(7):917-924
BACKGROUND: There are known racial disparities in renal graft survival. Data are lacking comparing associations of race/ethnicity and socioeconomic status with graft failure and functional status after transplantation. Our goal was to test if African-American and Hispanic race/ethnicity and poverty are associated with worse outcomes following renal transplantation. METHODS: We performed a retrospective cohort study using a nationwide registry (United Network for Organ Sharing). We studied 4,471 adults who received renal transplants in 1990. Outcomes were graft failure and functional status over 10 years. RESULTS: Cumulative incidence of graft failure was higher among African-Americans and Hispanics than whites (77% vs. 64% vs. 60 %; P<0.001) and among transplant recipients living in the poorest areas (70% vs. 58% in the richest; P<0.001). African-American and Hispanic race/ethnicity were independently predictive of graft failure (RR 1.8, 95% CI 1.6-1.9; RR 1.3, 95% CI 1.2-1.6, respectively) in multivariate analyses but poverty status was not (RR 1.0, 95% CI 0.9-1.1). Days with impaired functional status were higher for African-Americans compared to whites (RR 1.6, 95% CI 1.3-1.9) but not independent of poverty. Poverty was independently associated with impaired functional status (RR 1.3, 95% CI 1.0-1.6). CONCLUSIONS: African-Americans and Hispanics had higher rates of graft failure compared to whites after adjustment for poverty and other covariates whereas poverty, but not race/ethnicity, was related to functional status following renal transplantation. National datasets should include individual-level measures of socioeconomic status in order to improve evaluation of social and environmental causes of disparities in renal transplant outcomes. 相似文献
992.
993.
Effect of prone positioning on clinical outcomes in children with acute lung injury: a randomized controlled trial 总被引:15,自引:0,他引:15
Curley MA Hibberd PL Fineman LD Wypij D Shih MC Thompson JE Grant MJ Barr FE Cvijanovich NZ Sorce L Luckett PM Matthay MA Arnold JH 《JAMA》2005,294(2):229-237
Context In uncontrolled clinical studies, prone positioning appeared to be safe and to improve oxygenation in pediatric patients with acute lung injury. However, the effect of prone positioning on clinical outcomes in children is not known. Objective To test the hypothesis that at the end of 28 days infants and children with acute lung injury treated with prone positioning would have more ventilator-free days than those treated with supine positioning. Design, Setting, and Patients Multicenter, randomized, controlled clinical trial conducted from August 28, 2001, to April 23, 2004, of 102 pediatric patients from 7 US pediatric intensive care units aged 2 weeks to 18 years who were treated with supine vs prone positioning. Randomization was concealed and group assignment was not blinded. Intervention Patients were randomized to either supine or prone positioning within 48 hours of meeting acute lung injury criteria, with those patients in the prone group being positioned within 4 hours of randomization and remaining prone for 20 hours each day during the acute phase of their illness for a maximum of 7 days, after which they were positioned supine. Both groups were treated using lung protective ventilator and sedation protocols, extubation readiness testing, and hemodynamic, nutrition, and skin care guidelines. Main Outcome Measure Ventilator-free days to day 28. Results The trial was stopped at the planned interim analysis on the basis of the prespecified futility stopping rule. There were no differences in the number of ventilator-free days between the 2 groups (mean [SD], 15.8 [8.5] supine vs 15.6 [8.6] prone; mean difference, 0.2 days; 95% CI, 3.6 to 3.2; P = .91). After controlling for age, Pediatric Risk of Mortality III score, direct vs indirect acute lung injury, and mode of mechanical ventilation at enrollment, the adjusted difference in ventilator-free days was 0.3 days (95% CI, 3.0 to 3.5; P = .87). There were no differences in the secondary end points, including proportion alive and ventilator-free on day 28 (P = .45), mortality from all causes (P>.99), the time to recovery of lung injury (P = .78), organ-failurefree days (P = .88), and cognitive impairment (P = .16) or overall functional health (P = .12) at hospital discharge or on day 28. Conclusion Prone positioning does not significantly reduce ventilator-free days or improve other clinical outcomes in pediatric patients with acute lung injury. 相似文献
994.
995.
BACKGROUND: Although rarely life-threatening, postoperative vomiting (POV) is a distressing complication. The incidence of POV ranges from 34 to 90% in children undergoing strabismus surgery when antiemetics are not administered prophylactically. METHODS: In this study, a cost-consequence analysis (CCA) is used to estimate the economic benefit of ondansetron and dimenhydrinate as antiemetics administered prophylactically in children undergoing strabismus surgery. This retrospective study was conducted at The Hospital for Sick Children based on a review of 70 charts. RESULTS: Ondansetron was more effective with 45.3 POV-free patients (PFP) in an adjusted cohort of 100, while dimenhydrinate resulted in 38.2 PFP in an adjusted cohort of 100. The costs were significantly different between the two groups, CAD dollars 185.90 (+/-26.37, 95% CI, CAD dollars 173,89; CAD dollars 197.90) and CAD dollars 232.90 (+/-CAD dollars 66.84, 95% CI, CAD dollars 198.53; CAD dollars 267.27) per patient for ondansetron and dimenhydrinate, respectively. The length of stay in the postanesthetic care unit (PACU) represented over 97% of total costs, and the mean lengths of stay in the PACU for ondansetron and dimenhydrinate were significantly different, 3.43 and 4.41 h, respectively. CONCLUSION: This study should serve as a pilot for a large-scale investigation on the correlation between the length of stay in the PACU and the antiemetic agent used. 相似文献
996.
Baldwin ZK Chandiwal A Balasubramanian V Pearce BJ Curi MA Skelly CL Huang WW Vosicky JE Roizman B Weichselbaum RR Schwartz LB 《Journal of vascular surgery》2005,41(1):115-121
OBJECTIVE: Vascular remodeling in response to injury or low shear stress (or both) is characterized by neointimal hyperplasia and luminal contraction. When profound, the response leads to restenosis after percutaneous endovascular intervention as well as to de novo stenosis in vein grafts. It has recently been reported that exposure of vein patches to neurovirulence-attenuated Herpes simplex virus-1 (HSV-1) decreases neointimal hyperplasia and increases luminal area. This experiment tested the hypothesis that R7020, a more highly attenuated mutant of HSV-1, would modulate the vascular remodeling response of experimental vein grafts chronically exposed to low shear stress. METHODS: The external jugular veins of 31 New Zealand white rabbits were clamped and intraluminally exposed to vehicle (phospate-buffered saline solution, n = 11), R7020 2.5 x 10(8) plaque forming units [PFU]/mL (n = 8), or R7020 2.5 x 10(9) PFU/mL (n = 12) for 10 or 30 minutes at an average pressure of 80 mm Hg. After exposure, an end-to-side distal external jugular-to-common carotid artery anastomosis was created, resulting in a widely patent arteriovenous fistula. The external jugular was suture-ligated just proximal to the thoracic inlet, distal to a small 10- to 50-microm venous tributary, creating a reversed vein "graft" segment immediately and abruptly exposed to arterial pressure (48 +/- 3 mm Hg) and low shear stress (0.12 +/- .02 dyne/cm(2)). In the 29 animals (N = 31) that survived to harvest, 26 grafts were found to be patent and were analyzed further. Nine grafts were harvested within the first week after operation, snap frozen in liquid nitrogen, and assayed for the presence of the Herpes viral immediate-response protein ICP0 by Western blot analysis. The 17 remaining grafts were perfusion-fixed, excised, stained, and analyzed morphometrically by digital planimetry. RESULTS: In patent grafts, the hemodynamic environment of low shear stress was maintained (shear stress at harvest, 0.26 +/- .06 dyne/cm(2)). Western blot analysis revealed the presence of ICP0 in R7020-exposed vein grafts after 2, 3, 7, and 14 days; ICP0 was not detected in unexposed vein grafts or adjacent carotid arteries. After 4 weeks, vein grafts exposed to R7020 exhibited a statistically significantly increased ratio of luminal radius to wall thickness, indicating altered remodeling (vehicle, 6.7 +/- 1.3; R7020 2.5 x 10(8), 9.1 +/- 1.3; R7020 2.5 x 10(9) ratio, 11.3 +/- 1.4; P < .05 for high dose compared with vehicle). CONCLUSION: A brief exposure of the neurovirulence-attenuated HSV-1 strain R7020 results in an increased ratio of luminal radius to wall thickness in experimental vein grafts chronically exposed to low shear stress. 相似文献
997.
Diagnosis and management of bile leaks after blunt liver injury 总被引:5,自引:0,他引:5
BACKGROUND: Nonoperative management (NOM) of blunt liver injuries (BLIs) is common, but little data exist on the management of complications related to NOM. Furthermore, bile leaks are emerging as frequent complications of NOM. The goal of this study was to determine which BLI patients are at greatest risk for bile leaks and how to manage this complication. METHODS: Patients treated with NOM, including angiographic embolization (AE) and observation, were compared with those undergoing operation (OR). Mortality, hospital length of stay, liver-related complications, and severity of liver injury were compared among the groups. RESULTS: Two hundred eighty-one patients sustained a BLI from 1997 through 2004. The Injury Severity Score and age of the groups were similar. The mortality rate of the OR patients was higher (P = .02). All bile leaks occurred in patients with a liver Abbreviated Injury Score (AIS) of > or = 4. For survivors of more than 4 days, 71% of OR, 50% of AE, and 17% of observed patients developed bile leaks. For the OR and AE groups, HIDA scanning detected all leaks, leading to earlier drainage procedures. Detection of a bile leak in NOM patients before 5 days of hospitalization led to shorter HLOS, P = .02. No patient with a negative HIDA scan developed a subsequent bile leak. CONCLUSIONS: NOM of BLIs is associated with lower mortality, but significant complications. Bile leaks are more common in patients with higher liver AIS, and in this study presented in only those with liver AIS > or = 4. HIDA scanning successfully diagnosed all patients with bile leaks and led to less invasive drainage procedures over time and shorter HLOS. 相似文献
998.
999.
1000.
Use of extended pattern technique for initial prostate biopsy 总被引:2,自引:0,他引:2
PURPOSE: An extended prostate biopsy schema has been advocated at initial prostate biopsy to decrease the rate of false-negative cancer cases. However, critics have raised concerns that this may lead to the greater detection of clinically insignificant cancers. We examined the impact of using an extended pattern schema on cancer detection and also on the finding of smaller and clinically insignificant cancer. MATERIALS AND METHODS: Clinical data, including patient age, race, prebiopsy prostate specific antigen (PSA), digital rectal examination, prostate volume, number of needle cores and biopsy findings were abstracted from the medical records of all patients who underwent prostate biopsy in a 5-year period. Extended pattern prostate biopsy was defined as more than 10 cores. Clinically insignificant cancer was defined as a maximal tumor dimension of 1.0 cm or less, Gleason sum 6 or less and organ confined disease at radical prostatectomy. Adjusted regression models were developed to assess the independent effects of using an extended biopsy pattern on the detection of cancer overall and on the detection of clinically insignificant cancer. RESULTS: A total of 740 men with a mean age of 62.6 years were referred for prostate biopsy. Median PSA was 5.7 ng/ml and prostate volume was 39.7 cc. The OR for detecting prostate cancer was 1.55 (95% CI 1.09 to 2.19) for the extended pattern compared with standard biopsy. Of the subset of 136 patients who underwent radical prostatectomy 12.6% had clinically insignificant cancer. However, in contrast to overall cancer detection, extended pattern prostate biopsy was not found to be associated with an increased risk of detecting smaller or clinically insignificant cancer. PSA density was the single parameter found to be independently associated with the detection of clinically insignificant cancer (95% CI 0.20 to 0.98). CONCLUSIONS: Using an extended prostate biopsy pattern involving more than 10 cores increases the likelihood of detecting prostate cancer. A significant association between more needle cores at initial prostate biopsy and finding smaller and clinically insignificant cancer was not apparent. 相似文献