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   62895篇
  免费   4267篇
  国内免费   62篇
耳鼻咽喉   686篇
儿科学   1871篇
妇产科学   2487篇
基础医学   7765篇
口腔科学   2808篇
临床医学   7061篇
内科学   12019篇
皮肤病学   1117篇
神经病学   4637篇
特种医学   2382篇
外科学   10416篇
综合类   406篇
一般理论   44篇
预防医学   5020篇
眼科学   1930篇
药学   2846篇
中国医学   13篇
肿瘤学   3716篇
  2023年   1380篇
  2022年   1990篇
  2021年   2248篇
  2020年   2256篇
  2019年   1487篇
  2018年   1638篇
  2017年   1605篇
  2016年   1543篇
  2015年   1464篇
  2014年   2939篇
  2013年   2675篇
  2012年   2466篇
  2011年   2522篇
  2010年   2264篇
  2009年   2403篇
  2008年   2451篇
  2007年   2724篇
  2006年   2504篇
  2005年   2330篇
  2004年   2313篇
  2003年   2191篇
  2002年   2151篇
  2001年   2034篇
  2000年   1943篇
  1999年   1584篇
  1998年   620篇
  1997年   532篇
  1996年   545篇
  1995年   504篇
  1994年   496篇
  1993年   434篇
  1992年   1164篇
  1991年   1211篇
  1990年   1217篇
  1989年   1108篇
  1988年   1109篇
  1987年   583篇
  1986年   218篇
  1985年   368篇
  1984年   386篇
  1983年   323篇
  1982年   330篇
  1981年   286篇
  1980年   253篇
  1979年   246篇
  1978年   211篇
  1977年   191篇
  1976年   210篇
  1975年   179篇
  1974年   184篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
BackgroundThe futility of liver transplantation in elderly recipients remains under debate in the HCV eradication era.MethodsThe aim was to assess the effect of older age on outcome after liver transplantation. We used the ELTR to study the relationship between recipient age and post-transplant outcome. Young and elderly recipients were compared using a PSM method.ResultsA total of 10,172 cases were analysed. Recipient age >65 years was identified as an independent risk factor associated with reduced patient survival (HR:1.42 95%CI:1.23–1.65,p < 0.001). After PSM, 2124 patients were matched, and the same association was found between elderly recipients and patient survival and graft survival (p < 0.001). As hepatocellular carcinoma and alcoholic cirrhosis were independent prognostic factors for patient and graft survival a propensity score-matching was performed for each. Patient and graft survival were significantly worse (p < 0.05) in the alcoholic cirrhosis elderly group. However, patient and graft survival in the hepatocellular carcinoma cohort were similar (p > 0.05) between groups.ConclusionLiver transplantation is an acceptable and safe curative option for elderly transplant candidates, with worse long-term outcomes compare to young candidates. The underlying liver disease for liver transplantation has a significant impact on the selection of elderly patients.  相似文献   
2.
3.
4.
5.
BackgroundDespite high rate of cure in acute promyelocytic leukemia (APL) in clinical trials, outcomes in real-world practice are dismal. We utilized National Cancer Database (NCDB) to explore utilization of multiagent therapy in APL and identify any disparities in treatment in real-world practices.Patients and MethodsNCDB categorizes use of systemic chemotherapy into single agent versus multiagent therapy. Some patients received hormonal therapy, immunotherapy, and unknown therapy; details of these treatments could not be ascertained. We therefore used multiple logistic regression analysis to evaluate effects of covariates on the probability of multiagent therapy use in 6678 patients.ResultsCompared to patients >60 years, patients aged 0 to 18 years (hazard ratio[HR] 3.2, 95% confidence interval [CI] 1.8-5.5, P< .0001), 19 to 40 years (HR 1.6, 95% CI 1.03-2.54, P= .03), and 41 to 60 years (HR 1.6, 95% CI 1.3-1.9, P< .0001) were more likely to receive multiagent therapy. Patients with Charlson comorbidity index (CCI) of 0 (HR 1.6, 95% CI 1.2-2.3, P= .001) and CCI of 1 (HR 1.4, 95% CI 1.0-1.9, P= .04) had a higher likelihood of receiving multiagent therapy than patients with CCI ≥ 3. Patients treated at academic cancer centers, compared to those treated at community cancer center (HR 0.5, 95% CI 0.3-0.7, P= .001), comprehensive community cancer center (HR 0.7, 95% CI 0.6-0.8, P< .0001), and integrated network cancer center (HR 0.8, 95% CI 0.6-0.9, P= .02) were more likely to be treated with multiagent therapy. Compared to the patients with private insurance, those with Medicaid had increased likelihood (HR 1.2, 95% CI 1.0-1.4, P= .04) whereas uninsured patients had a lower likelihood of receiving multiagent therapy (HR 0.6, 95% CI 0.5-0.8, P= .0005).ConclusionTo our knowledge, this study is the first and the largest scale analysis of treatment practices in APL in real-world practices. Our findings highlight significant disparities in treatment of APL based on age, insurance, and health-system factors.  相似文献   
6.
BackgroundSurgical resection is recommended for patients with resectable acinar cell carcinoma (ACC). The aim of this study was to investigate the clinical characteristics and surgical outcomes of resectable ACC in comparison to pancreatic ductal adenocarcinoma (PDAC).MethodA retrospective analysis was performed on all patients who consecutively underwent radical resection with pathologically confirmed ACC and PDAC from December 2011 to December 2018. Clinicopathologic characteristics and follow-up information were analyzed. A 1:3 propensity score matching (PSM) method was used to minimize the bias between ACC and PDAC.ResultsA total of 26 patients with ACC and 1351 with PDAC were included. Compared to PDAC, ACC tended to be larger (4.5 vs. 3.0 cm; p < 0.001) and more frequently located in the pancreatic body/tail (61.5% vs. 36.6%, p = 0.009), with lower total bilirubin levels, lower neutrophil lymphocyte ratio (NLR) levels and lower carbohydrate antigen 19-9 (CA19-9) levels and carcinoembryonic antigen (CEA) levels. There was no difference in postoperative morbidities in patients with ACC and PDAC. The median OS and RFS were longer in ACC when compared to PDAC (OS: 43.5 mo vs. 19.0 mo, p = 0.004; RFS: 24.5 mo vs. 11.6 mo, p = 0.023). After the 1:3 PSM, ACC remained to be a better histological type for OS (p = 0.024), but had comparable RFS with PDAC (p = 0.164).ConclusionPatients with ACC after radical resection had better OS than that with PDAC. However, ACC is also an aggressive tumor with a similar trend of RFS with PDAC after the matching, necessitating the multidisciplinary treatment for resectable ACC disease.  相似文献   
7.
《Survey of ophthalmology》2023,68(5):920-928
There remains limited agreement regarding the efficacy and safety of different antivascular endothelial growth factor (anti-VEGF) agents for the management of polypoidal choroidal vasculopathy (PCV). Our meta-analysis compares different anti-VEGF agents for PCV treatment. Ovid MEDLINE, EMBASE, and Cochrane Library were systematically searched from January 2000 to July 2022. We included articles comparing the efficacy and safety of different anti-VEGF agents, specifically bevacizumab (BEV), ranibizumab (RAN), aflibercept AFL), and brolucizumab (BRO), for patients with PCV. 10,440 studies were identified, 122 underwent full-text review, and seven were included. One study was a randomized trial, and six were observational studies. Ranibizumab and aflibercept were associated with a similar best-corrected visual acuity (BCVA) at the last visit in three observational studies (P = 0.10), similar retinal thickness at the last visit in two observational studies (P = 0.85). One observational study comparing BEV versus RAN found comparable outcomes for final BCVA, retinal thickness, and polyp regression. One randomized trial on BRO versus AFL found comparable outcomes for improvement in BCVA, while anatomical outcomes favored BRO. The available evidence suggests that final BCVA is comparable across different anti-VEGF agents, however, further investigation is warranted due to paucity of evidence.  相似文献   
8.
9.
The seventh leading cause of cancer-related death globally, pancreatic ductal adenocarcinoma (PDAC) involves the exocrine pancreas and constitutes greater than 90% of all pancreatic cancers. Surgical resection in combination with systemic chemotherapy with or without radiation remains the mainstay of treatment and the only potentially curative treatment option. While there has been improvement in systemic chemotherapy, long-term survival among patients with PDAC remains poor. Improvement in the understanding of tumorigenesis, genetic mutations, the tumor microenvironment (TME), immunotherapies, as well as targeted therapies continued to drive advances in PDAC treatment. We herein review the TME, genetic landscape, as well as various metabolic pathways associated with PDAC tumorigenesis relative to emerging therapies.  相似文献   
10.
BackgroundPseudomyxoma peritonei (PMP) is a rare clinical entity, commonly derived from a mucin-producing tumour of the appendix. International consensus is unclear on the role of positron emission tomography (PET) in preoperative staging. This study aimed to assess the ability of preoperative PET in predicting the histological grade of PMP.MethodsAll patients scheduled for cytoreductive surgery (CRS) +/? hyperthermic intraperitoneal chemotherapy (HIPEC) for PMP who underwent preoperative PET at a single centre between June 2007 and June 2020 were included. A nuclear medicine physician, blinded to patient outcomes, retrospectively reviewed imaging studies to assess for maximum tumour standardised uptake value (SUV) to mean liver SUV ratio (SUVTLR) and maximum porta hepatis SUV to mean liver SUV ratio (SUVPLR).ResultsBetween April 2007 and December 2020, a total of 204 patients underwent surgical intervention for PMP. Of these, 124 (60.8%) met the inclusion criteria. Median peritoneal carcinomatosis index for the entire cohort was 9 and complete cytoreduction (CC0/1) was achieved in 109 (88%) patients. Patients with high-grade PMP were more likely to have diffuse peritoneal disease (p < 0.001) and higher SUVTLR (p<0.001). The area under the ROC curve (AUC) of SUVTLR in predicting high-grade pathology was 71% (p = 0.003). Patients with a SUVTLR ≤ 0.78 had improved disease-free survival (p = 0.042).ConclusionPreoperative PET showed positive correlation with high-grade PMP and acceptable sensitivity and specificity as a diagnostic tool. PET should be considered a useful adjunct to standard imaging for predicting histological grade in the staging of patients with PMP.  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