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   2107篇
  免费   250篇
  国内免费   21篇
耳鼻咽喉   33篇
儿科学   52篇
妇产科学   29篇
基础医学   181篇
口腔科学   78篇
临床医学   359篇
内科学   394篇
皮肤病学   109篇
神经病学   93篇
特种医学   146篇
外科学   302篇
综合类   113篇
现状与发展   30篇
预防医学   235篇
眼科学   22篇
药学   103篇
中国医学   3篇
肿瘤学   96篇
  2024年   18篇
  2023年   181篇
  2022年   17篇
  2021年   20篇
  2020年   55篇
  2019年   31篇
  2018年   59篇
  2017年   53篇
  2016年   46篇
  2015年   64篇
  2014年   95篇
  2013年   83篇
  2012年   49篇
  2011年   58篇
  2010年   85篇
  2009年   103篇
  2008年   50篇
  2007年   78篇
  2006年   51篇
  2005年   58篇
  2004年   44篇
  2003年   58篇
  2002年   48篇
  2001年   36篇
  2000年   36篇
  1999年   44篇
  1998年   40篇
  1997年   56篇
  1996年   48篇
  1995年   41篇
  1994年   34篇
  1993年   40篇
  1992年   22篇
  1991年   32篇
  1990年   25篇
  1989年   39篇
  1988年   35篇
  1987年   33篇
  1986年   16篇
  1985年   25篇
  1983年   13篇
  1982年   11篇
  1981年   16篇
  1980年   18篇
  1978年   15篇
  1976年   20篇
  1975年   11篇
  1974年   11篇
  1929年   17篇
  1922年   9篇
排序方式: 共有2378条查询结果,搜索用时 15 毫秒
81.
82.
83.

Introduction

Current National Comprehensive Cancer Network guidelines recommend neoadjuvant therapy for borderline resectable pancreatic adenocarcinoma to increase the likelihood of achieving R0 resection. A consensus has not been reached on the degree of venous involvement that constitutes borderline resectability. This study compares the outcome of patients who underwent pancreaticoduodenectomy with or without vein resection without neoadjuvant therapy.

Methods

A multi-institutional database of patients who underwent pancreaticoduodenectomy was reviewed. Patients who required vein resection due to gross vein involvement by tumor were compared to those without evidence of vein involvement.

Results

Of 492 patients undergoing pancreaticoduodenectomy, 70 (14 %) had vein resection and 422 (86 %) did not. There was no difference in R0 resection (66 vs. 75 %, p?=?NS). On multivariate analysis, vein involvement was not predictive of disease-free or overall survival.

Conclusion

This is the largest modern series examining patients with or without isolated vein involvement by pancreas cancer, none of whom received neoadjuvant therapy. Oncological outcome was not different between the two groups. These data suggest that up-front surgical resection is an appropriate option and call into question the inclusion of isolated vein involvement in the definition of “borderline resectable disease.”  相似文献   
84.
85.
86.
87.
88.

Background

This study utilized a multi-institutional database to evaluate risk factors for readmission in patients undergoing curative gastrectomy for gastric adenocarcinoma with the intent of describing both perioperative risk factors and the relationship of readmission to survival.

Methods

Patients who underwent curative resection of gastric adenocarcinoma from 2000 to 2012 from seven academic institutions of the US Gastric Cancer Collaborative were analyzed. In-hospital deaths and palliative surgeries were excluded, and readmission was defined as within 30 days of discharge. Univariate and multivariable logistic regression analyses were employed and survival analysis conducted.

Results

Of the 855 patients, 121 patients (14.2 %) were readmitted. Univariate analysis identified advanced age (p?<?0.0128), American Society of Anesthesiology status ≥3 (p?=?0.0045), preexisting cardiac disease (p?<?0.0001), hypertension (p?=?0.0142), history of smoking (p?=?0.0254), increased preoperative blood urea nitrogen (BUN; p?=?0.0426), concomitant pancreatectomy (p?=?0.0056), increased operation time (p?=?0.0384), estimated blood loss (p?=?0.0196), 25th percentile length of stay (<7 days, p?=?0.0166), 75th percentile length of stay (>12 days, p?=?0.0256), postoperative complication (p?<?0.0001), and total gastrectomy (p?=?0.0167) as risk factors for readmission. Multivariable analysis identified cardiac disease (odds ratio (OR) 2.4, 95 % confidence interval (CI) 1.6–3.3, p?<?0.0001), postoperative complication (OR 2.3, 95 % CI 1.6–5.4, p?<?0.0001), and pancreatectomy (OR 2.2, 95 % CI 1.1–4.1, p?=?0.0202) as independent risk factors for readmission. There was an association of decreased overall median survival in readmitted patients (39 months for readmitted vs. 103 months for non-readmitted). This was due to decreased survival in readmitted stage 1 (p?=?0.0039), while there was no difference in survival for other stages. Stage I readmitted patients had a higher incidence of cardiac disease than stage I non-readmitted patients (58 vs. 24 %, respectively, p?=?0.0002).

Conclusions

Within this multi-institutional study investigating readmission in patients undergoing curative resection for gastric cancer, cardiac disease, postoperative complication, and concomitant pancreatectomy were identified as significant risk factors for readmission. Readmission was associated with decreased overall median survival, but on further analysis, this was driven by differences in survival for stage I disease only.
  相似文献   
89.
The ehrlichiae express variable outer membrane proteins (OMPs) that play important roles in both pathogenesis and host defense. Previous studies revealed that OMPs are immunodominant B-cell antigens and that passive transfer of anti-OMP antibodies can protect SCID mice from fatal ehrlichial infection. In this study, we used a model of fatal monocytotropic ehrlichiosis caused by Ehrlichia bacteria from Ixodes ovatus (IOE) to determine whether OMP immunization could generate protective immunity in immunocompetent mice. Immunization of C57BL/6 mice with a purified recombinant OMP expressed by IOE omp19 generated protection from fatal IOE infection and elicited robust humoral and CD4 T-cell responses. To identify CD4 T-cell epitopes within OMPs, we performed enzyme-linked immunospot analyses for gamma interferon (IFN-gamma) production using a panel of overlapping 16-mer peptides from IOE OMP-19. Five immunoreactive peptides comprising residues 30 to 45, 77 to 92, 107 to 122, 197 to 212, and 247 to 264 were identified; the strongest response was generated against OMP-19(107-122). Most of the peptides are conserved between E. muris and E. chaffeensis OMP-19, and they elicited IFN-gamma production in CD4 T cells from E. muris-infected mice, indicating that T-cell epitope cross-reactivity likely contributes to heterologous immunity. Accordingly, CD4 T-cell responses to both OMP-19 and OMP-19(107-122) were of greater magnitude following high-dose IOE challenge of mice that had been immunized by prior infection with E. muris. Our studies cumulatively identify B- and T-cell epitopes that are associated with protective homologous and heterologous immunity during ehrlichial infection.  相似文献   
90.

Background

Late or inadequate therapeutic management increases the risk of mortality associated with HIV/AIDS. The aim of this study was to analyze the proportion and factors associated with loss of follow-up in HIV patients who receiving antiretroviral therapy at Conakry.

Methods

A retrospective cohort study was conducted in HIV patients aged over 15 years and who receiving antiretroviral therapy. Between August 1, 2008 and July 31, 2015, all patients managed by the ambulatory treatment center of the Guinean Women Association against AIDS and sexually and transmissible infection were included. Loss of follow-up was defined as no follow-up visit within 3 months. Kaplan–Meier curves and multivariate Cox regression models were used to analyze factors associated with loss of follow-up. Analyses were performed by using Stata 13 software.

Results

614 patients aged 36.3 ± 11.2 years, mainly females (68.4%) and living in Conakry (80.5%) were included. Among them, 104 were loss to follow-up, corresponding to a proportion rate of 16.9% (95% CI: 14.2–19.7%) or 5.79/100 person-years. The results of multivariate analyses showed that factors independently associated with loss of follow-up were malnutrition (AHR = 7.05; 95% CI: 2.05–24.27; P = 0.002) and CD4 cells account at the initiation of AHR (2.35; 95% CI: 1.61–6.39; P = 0.016) in patients with 201–350 CD4/μL and 5.83 (95% CI: 2.85–11.90; P < 0.001) in patients with less than 150 CD4/μL.

Conclusion

Despite efforts of health care workers and free antiretroviral therapy, many patients were loss to follow-up. Multivariate analysis showed that malnutrition and low CD4 account were independently associated with loss to follow-up.  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