全文获取类型
收费全文 | 2356937篇 |
免费 | 198036篇 |
国内免费 | 4175篇 |
专业分类
耳鼻咽喉 | 34235篇 |
儿科学 | 72522篇 |
妇产科学 | 62917篇 |
基础医学 | 332050篇 |
口腔科学 | 67458篇 |
临床医学 | 214287篇 |
内科学 | 464195篇 |
皮肤病学 | 47891篇 |
神经病学 | 199276篇 |
特种医学 | 95844篇 |
外国民族医学 | 886篇 |
外科学 | 359324篇 |
综合类 | 56147篇 |
现状与发展 | 1篇 |
一般理论 | 977篇 |
预防医学 | 189120篇 |
眼科学 | 55325篇 |
药学 | 177014篇 |
4篇 | |
中国医学 | 4258篇 |
肿瘤学 | 125417篇 |
出版年
2018年 | 24210篇 |
2016年 | 20571篇 |
2015年 | 23278篇 |
2014年 | 33532篇 |
2013年 | 50827篇 |
2012年 | 68736篇 |
2011年 | 72274篇 |
2010年 | 42470篇 |
2009年 | 40860篇 |
2008年 | 68758篇 |
2007年 | 73101篇 |
2006年 | 74002篇 |
2005年 | 72036篇 |
2004年 | 69298篇 |
2003年 | 66863篇 |
2002年 | 66097篇 |
2001年 | 112284篇 |
2000年 | 116227篇 |
1999年 | 97685篇 |
1998年 | 26155篇 |
1997年 | 23778篇 |
1996年 | 23734篇 |
1995年 | 24451篇 |
1994年 | 23021篇 |
1993年 | 21429篇 |
1992年 | 79261篇 |
1991年 | 76374篇 |
1990年 | 73532篇 |
1989年 | 70790篇 |
1988年 | 65776篇 |
1987年 | 64749篇 |
1986年 | 61288篇 |
1985年 | 58365篇 |
1984年 | 44145篇 |
1983年 | 37541篇 |
1982年 | 22794篇 |
1981年 | 20227篇 |
1980年 | 18934篇 |
1979年 | 41223篇 |
1978年 | 28910篇 |
1977年 | 24246篇 |
1976年 | 22753篇 |
1975年 | 23902篇 |
1974年 | 29585篇 |
1973年 | 28008篇 |
1972年 | 26204篇 |
1971年 | 24141篇 |
1970年 | 22724篇 |
1969年 | 21062篇 |
1968年 | 19113篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
61.
Nicolas Zhou Matthew Bott Bernard J. Park Eric Vallières Candice L. Wilshire Kazuhiro Yasufuku Jonathan D. Spicer David R. Jones Boris Sepesi 《The Journal of thoracic and cardiovascular surgery》2021,161(3):760-771.e2
BackgroundAdjuvant chemotherapy, postoperative radiation (PORT), and prophylactic cranial irradiation (PCI) have been individually examined in limited-stage small cell lung cancer (SCLC). There is a paucity of data on the effectiveness of each adjuvant treatment modality when used in combination after surgical resection of SCLC.MethodsData were collected from 5 cancer centers on all patients with limited-stage SCLC who underwent surgical resection between 1986 and 2019. Univariate and multivariable models were conducted to identify predictors of long-term outcomes, focusing on freedom from recurrence and survival benefit of adjuvant chemotherapy, PORT, and PCI.ResultsA total of 164 patients were analyzed. Multivariable Cox regression analysis did not identify any adjuvant therapies to significantly influence recurrence in this cohort. Specifically, PORT was not associated with a significant influence on locoregional recurrence and PCI was not significantly associated with intracranial outcomes. Adjuvant chemotherapy improved survival in all stage I through III disease (hazard ratio, 0.49; 95% confidence interval, 0.29-0.81; P = .005) and even in pathologically node negative patients (hazard ratio, 0.49; 95% confidence interval, 0.27-0.91; P = .024). Although PCI was found to improve survival in univariate analysis, it was not significant in a multivariable model. PORT was not found to affect survival on either univariate or multivariable analysis.ConclusionsThis is among the largest multi-institutional studies on surgically resected limited-stage SCLC. Our results highlight survival benefit of adjuvant chemotherapy, but did not identify a statistically significant influence from mediastinal PORT or PCI in our cohort. Larger prospective studies are needed to determine the benefit of PORT or PCI in a surgically resected limited-stage SCLC population. 相似文献
62.
Balázs Nemes Réka P. Szabó Dávid Péntek Ildikó Nagy Gergely Ivády Bettina Kárai Eszter Szánthó Zsuzsa Hevessy Sándor Sipka Gergő J. Szőllősi Sándor Baráth 《Transplantation proceedings》2021,53(5):1423-1432
IntroductionThe usage of extended-criteria donors (ECD) became a routinely accepted manner in the last decade. ECD is a potential risk factor for antibody-mediated rejection. Analysis of lymphocyte subsets might be a complementary diagnostic toolkit because there is limited knowledge about this term.MethodBetween May 12, 2016, and September 4, 2019, a total of 130 patients who had undergone kidney transplant were investigated. Patients were divided in ECD and standard criteria donor (SCD) groups. Blood samples were collected before the operation, then in the first week and after 30, 60, 180, and 365 days. Besides routine laboratory tests, multicolor flow cytometry was performed for lymphocyte subsets.ResultsECD grafts were transplanted to older recipients. The number of CD4+ cells increased in the SCDs from the first week to until the end of first month, and then decreased. The number of CD4+ cells decreased from the beginning of the study until the end of first year to 66% of its original value in ECDs. At the first month, the number of CD19+ cells was higher in SCD compared with ECD cases; the number then decreased in both groups. T-regulatory cells had a drop at the first week that lasted until the first month. A bigger increase in SCD and a moderate increase in ECD group were then observed. The kinetics of CD19+ and CD19+ naive cells are similar in the ECD and SCD groups. In the SCD group, cell count decreased in both CD19+ (13%) and CD19+ naive (12%) between third and sixth month. The count of CD19+ cells decreased by 9%, but the count of CD19+ naive cells increased by 11% between the sixth month and first year.DiscussionThe prolonged postoperative uremic state caused by the poorer initial function, together with an aging immune system, explains the weaker immune response in ECD patients, which may be the cause of the decreased number of memory and regulatory T cells. Older patients with an ECD graft need a tailored, personalized, and less aggressive immunosuppressive treatment. 相似文献
63.
64.
65.
66.
J. Ripollés-Melchor C. Aldecoa E. Alday-Muñoz S. del Río A. Batalla E. del-Cojo-Peces R. Uña-Orejón J.L. Muñoz-Rodés J.V. Lorente Á.V. Espinosa C. Ferrando-Ortolà J.L. Jover A. Abad-Gurumeta J.M. Ramírez-Rodríguez A. Abad-Motos 《Revista espa?ola de anestesiología y reanimación》2021,68(7):373-383
BackgroundThe optimal regimen for intravenous administration of intraoperative fluids remains unclear. Our goal was to analyze intraoperative crystalloid volume administration practices and their association with postoperative outcomes.MethodsWe extracted clinical data from two multicenter observational studies including adult patients undergoing colorectal surgery and total hip (THA) and knee arthroplasty (TKA). We analyzed the distribution of intraoperative fluid administration. Regression was performed using a general linear model to determine factors predictive of fluid administration. Patient outcomes and intraoperative crystalloid utilization were summarized for each surgical cohort. Regression models were developed to evaluate associations of high or low intraoperative crystalloid with the likelihood of increased postoperative complications, mainly acute kidney injury (AKI) and hospital length of stay (LOS).Results7,580 patients were included. The average adjusted intraoperative crystalloid infusion rate across all surgeries was to 7.9 (SD 4) mL/kg/h. The regression model strongly favored the type of surgery over other patient predictors. We found that high fluid volume was associated with 40% greater odds ratio (OR 1.40; 95% confidence interval1.01-1.95, p = 0.044) of postoperative complications in patients undergoing THA, while we found no associations for the other types of surgeries, AKI and LOSConclusionsA wide variability was observed in intraoperative crystalloid volume administration; however, this did not affect postoperative outcomes. 相似文献
67.
C. Vogrig J.-S. Louis F. Avila R. Gillet G. Hossu A. Blum-Moyse P.A. Gondim Teixeira 《Diagnostic and interventional imaging》2021,102(3):181-187
PurposeThe purpose of this study was to compare morphologic assessment and relaxometry of patellar hyaline cartilage between conventional sequences (fast spin-echo [FSE] T2-weighted fat-saturated and T2-mapping) and synthetic T2 short-TI inversion recovery (STIR) and T2 maps at 1.5 T magnetic resonance imaging (MRI).MethodThe MRI examinations of the knee obtained at 1.5 T in 49 consecutive patients were retrospectively studied. There were 21 men and 28 women with a mean age of 45 ± 17.7 (SD) years (range: 18–88 years). Conventional and synthetic acquisitions were performed, including T2-weighted fat-saturated and T2-mapping sequences. Two radiologists independently compared patellar cartilage T2-relaxation time on conventional T2-mapping and synthetic T2-mapping images. A third radiologist evaluated the patellar cartilage morphology on conventional and synthetic T2-weighted images. The presence of artifacts was also assessed. Interobserver agreement for quantitative variables was assessed using intraclass correlation coefficient (ICC).ResultsIn vitro, conventional and synthetic T2 maps yielded similar mean T2 values 58.5 ± 2.3 (SD) ms and 58.8 ± 2.6 (SD) ms, respectively (P = 0.414) and 6% lower than the expected experimental values (P = 0.038). Synthetic images allowed for a 15% reduction in examination time compared to conventional images. On conventional sequences, patellar chondropathy was identified in 35 patients (35/49; 71%) with a mean chondropathy grade of 4.8 ± 4.8 (SD). On synthetic images, 28 patients (28/49; 57%) were diagnosed with patellar chondropathy, with a significant 14% difference (P = 0.009) and lower chondropathy scores (3.7 ± 4.9 [SD]) compared to conventional images. Motion artifacts were more frequently observed on synthetic images (18%) than on conventional ones (6%). The interobserver agreement was excellent for both conventional and synthetic T2 maps (ICC > 0.83). Mean cartilage T2 values were significantly greater on synthetic images (36.2 ± 3.8 [SD] ms; range: 29-46 ms) relative to conventional T2 maps (31.8 ± 4.1 [SD] ms; range: 26-49 ms) (P < 0.0001).ConclusionDespite a decrease in examination duration, synthetic images convey lower diagnostic performance for chondropathy, greater prevalence of motion artifacts, and an overestimation of T2 values compared to conventional MRI sequences. 相似文献
68.
69.
70.