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   36969篇
  免费   2228篇
  国内免费   201篇
耳鼻咽喉   425篇
儿科学   1151篇
妇产科学   997篇
基础医学   3687篇
口腔科学   1203篇
临床医学   3251篇
内科学   7999篇
皮肤病学   670篇
神经病学   2209篇
特种医学   1313篇
外国民族医学   4篇
外科学   6769篇
综合类   854篇
现状与发展   3篇
一般理论   27篇
预防医学   2498篇
眼科学   1355篇
药学   2848篇
  1篇
中国医学   266篇
肿瘤学   1868篇
  2024年   39篇
  2023年   408篇
  2022年   1043篇
  2021年   1641篇
  2020年   983篇
  2019年   1255篇
  2018年   1566篇
  2017年   1136篇
  2016年   1232篇
  2015年   1329篇
  2014年   1681篇
  2013年   2048篇
  2012年   3095篇
  2011年   2991篇
  2010年   1688篇
  2009年   1462篇
  2008年   2221篇
  2007年   2291篇
  2006年   2020篇
  2005年   1787篇
  2004年   1622篇
  2003年   1348篇
  2002年   1177篇
  2001年   363篇
  2000年   306篇
  1999年   280篇
  1998年   197篇
  1997年   132篇
  1996年   141篇
  1995年   107篇
  1994年   95篇
  1993年   77篇
  1992年   147篇
  1991年   160篇
  1990年   128篇
  1989年   123篇
  1988年   104篇
  1987年   97篇
  1986年   88篇
  1985年   116篇
  1984年   77篇
  1983年   52篇
  1982年   53篇
  1981年   55篇
  1980年   41篇
  1979年   50篇
  1978年   40篇
  1975年   35篇
  1974年   36篇
  1973年   35篇
排序方式: 共有10000条查询结果,搜索用时 93 毫秒
941.
942.
943.
944.
945.
BACKGROUNDGastric antral vascular ectasia (GAVE) is a significant complication of cirrhosis. Numerous medical, surgical, and endoscopic treatment modalities have been proposed with varied satisfactory results. In a few small studies, GAVE and associated anemia have resolved after orthotopic liver transplantation (OLT). AIMTo assess the impact of OLT on the resolution of GAVE and related anemia.METHODSWe retrospectively reviewed clinical records of adult patients with GAVE who underwent OLT between September 2012 and September 2019. Demographics and other relevant clinical findings were collected, including hemoglobin levels and upper endoscopy findings before and after OLT. The primary outcome was the resolution of GAVE and its related anemia after OLT.RESULTSSixteen patients were identified. Mean pre-OLT Hgb was 7.7 g/dL and mean 12 mo post-OLT Hgb was 11.9 g/dL, (P = 0.001). Anemia improved (defined as Hgb increased by 2g) in 87.5% of patients within 6 to 12 mo after OLT and resolved completely in half of the patients. Post-OLT esophagogastroduodenoscopy was performed in 10 patients, and GAVE was found to have resolved entirely in 6 of those patients (60%). CONCLUSIONAlthough GAVE and associated anemia completely resolved in the majority of our patients after OLT, GAVE persisted in a few patients after transplant. Further studies in a large group of patients are necessary to understand the causality of disease and to better understand the factors associated with the persistence of GAVE post-transplant.  相似文献   
946.
Titanium dioxide thin films immobilized over treated stainless steel were prepared using the pulsed electrophoretic deposition technique. The effects of process parameters (deposition time, applied voltage, initial concentration, and duty cycle) on photocatalytic efficiency and adhesion properties were investigated. To optimize the multiple properties of the thin film, a response surface methodology was combined with a desirability optimization methodology. Additionally, a quadratic model was established based on response surface analysis. The precision of the models was defined based on the analysis of variance (ANOVA), R2, and the normal plot of residuals. Then, a desirability function was used to optimize the multiple responses of the TiO2 thin film. The optimum values of applied voltage, catalyst concentration, duty cycle, and deposition time were 4 V, 16.34 g/L, 90% DC, and 150 s, respectively. Under these conditions, the decolorization efficiency of tested dye solution reached 82.75%. The values of critical charges LC1, LC2, and LC3 were 5.9 N, 12.5 N, and 16.7 N, respectively.  相似文献   
947.
Objectives:To investigate the relationship between a prostasin gene variations and the development of preeclampsia in a Pakistani female population.Methods:This was a case-control study carried out at University of Karachi, Karachi, Pakistan between May 2018 and 2019. A single nucleotide polymorphism (SNP) at rs12597511 locus was examined with polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) analyses in 76 preeclamptic and 74 normotensive expecting mothers.Results:We observed significantly increased risk of preeclampsia associated with the CC genotype of rs12597511 polymorphism as compared to TT (p<0.001, OR=8.08, 95% CI:1.28-31.19) and TT/TC (p<0.001, OR=14.66 and 95% CI: 3.31-65.07) genotypes carriers. Calculation of the allelic distribution revealed a higher frequency of the T allele (82%) among controls; however, the C allele was more prevalent in the preeclamptic group (36%) significantly.Conclusion:The significantly higher C allele frequency in the prostasin gene at the rs12597511 locus in the preeclamptic group indicates that the distribution of the C allele of the prostasin gene is a potential risk factor contributing to the development of preeclampsia.  相似文献   
948.
Objectives:To explore the changing patterns of long-stay patients (LSP) to improve the utilization of pediatric intensive care units (PICUs) resources.Methods:This is a 2-points cross-sectional study (5 years apart; 2014-2019) conducted among PICUs and SCICUs in Riyadh, Saudi Arabia. Children who have stayed in PICU for more than 21 days were included.Results:Out of the 11 units approached, 10 (90%) agreed to participate. The prevalence of LSP in all these hospitals decreased from 32% (48/150) in 2014 to 23.4% (35/149) in 2019. The length of stay ranged from 22 days to 13.5 years. The majority of LSP had a neuromuscular or cardiac disease and were admitted with respiratory compromise. Ventilator-associated pneumonia was the most prevalent complication (37.5%). The most commonly used resources were mechanical ventilation (93.8%), antibiotics (60.4%), and blood-products transfusions (35.4%). The most common reason for the extended stay was medical reasons (51.1%), followed by a lack of family resources (26.5%) or lack of referral to long-term care facilities (22.4%).Conclusion:A long-stay is associated with significant critical care bed occupancy, complications, and utilization of resources that could be otherwise utilized as surge capacity for critical care services. Decreasing occupancy in this multicenter study deserves further engagement of the healthcare leaders and families to maximize the utilization of resources.  相似文献   
949.
Objectives:To identify pulmonary tuberculosis (PTB) delayed inpatient diagnosis duration and contributing factors in an academic center in Saudi Arabia (SA).Methods:Retrospective review of all culture-confirmed PTB cases between May 2015 and April 2019. The outcomes were the timing between admission and suspicion of PTB or isolation to either early group (within 24 hours of admission) and late group (24 hours after admission).Results:Forty-nine cases were included with a median age of 49 years; a third of them were above 65 years of age. Most patients were of Saudi nationality and male. Approximately 38% of the cases were in the delayed group, half of them were smear-positive, with an average delay of 5.5 days. This was significant with age above 65 years (odds ratio [OR]=8.93, 95% confidence interval [CI]=2.22-35.95) presence of non-respiratory symptoms (OR=5.6, 95% CI=1.56-19.98), malignancy (OR=13.38, 95% CI=1.46-122.71), chronic medical problems (OR=4.90, 95% CI=1.31-18.32), missed chest x-ray findings (OR= 48, 95% CI=8.63-266.88) or procalcitonin level above 0.5 ng/mL (OR=12, 95% CI=1.58-91.08).Conclusion:Physicians in SA need to have a low threshold for PTB consideration in elderly patients or those with a history of malignancy. A careful review of the initial chest x-ray might help to overcome missing cases of PTB.  相似文献   
950.
Objectives:To assess the quality and quantity of Saudi publications in oncology over a 10-year period.Methods:A systematic PubMed search was conducted between January 2008 and December 2017 to retrieve all Saudi oncology publications. Data about the articles was collected. The level of evidence (LOE) was independently assessed by 2 authors. Two 5-year periods (2008-2012 and 2013-2017) were compared using the relevant parameters. Clinicaltrials.gov was also searched for all oncology trials registered in Saudi Arabia.Results:A total of 839 publications met our inclusion criteria. The most common type of research was case series, totaling 32% of all publications. Clinical trials formed less than 2% of the total. The LOE was I, II, III, and IV in 0.3%, 2.1%, 58.4%, and 39.3% of the included publications, respectively. The LOE was the same in the 2 periods. There were more publications in international journals (p=0.004), more international collaborations (p=0.001), and higher journal impact factors (p=0.037) in 2013-2017 than in 2008-2012. Only 76 registered clinical trials were found in the Clinicaltrials.gov registry.Conclusion:Despite an increase in the number of Saudi publications in the field of oncology over time, the LOE did not change. There were, however, some improvements in the international collaboration and journal impact factor, as well as an increase in the number of studies published in international journals. These observations call for a national strategy to improve oncology research in Saudi Arabia.  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