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   811篇
  免费   59篇
  国内免费   11篇
耳鼻咽喉   5篇
儿科学   16篇
妇产科学   14篇
基础医学   57篇
口腔科学   63篇
临床医学   71篇
内科学   277篇
皮肤病学   35篇
神经病学   69篇
特种医学   84篇
外科学   44篇
综合类   15篇
预防医学   28篇
眼科学   4篇
药学   58篇
中国医学   20篇
肿瘤学   21篇
  2024年   3篇
  2023年   5篇
  2022年   18篇
  2021年   7篇
  2020年   10篇
  2019年   12篇
  2018年   13篇
  2017年   5篇
  2016年   9篇
  2015年   15篇
  2014年   13篇
  2013年   30篇
  2012年   26篇
  2011年   43篇
  2010年   36篇
  2009年   25篇
  2008年   29篇
  2007年   40篇
  2006年   23篇
  2005年   25篇
  2004年   20篇
  2003年   26篇
  2002年   24篇
  2001年   13篇
  2000年   10篇
  1999年   14篇
  1998年   28篇
  1997年   39篇
  1996年   37篇
  1995年   21篇
  1994年   24篇
  1993年   22篇
  1992年   10篇
  1991年   21篇
  1990年   13篇
  1989年   16篇
  1988年   23篇
  1987年   17篇
  1986年   19篇
  1985年   13篇
  1984年   10篇
  1983年   16篇
  1982年   20篇
  1981年   15篇
  1980年   7篇
  1979年   6篇
  1978年   2篇
  1976年   3篇
  1975年   2篇
  1970年   1篇
排序方式: 共有881条查询结果,搜索用时 15 毫秒
91.
92.
93.
94.
95.
96.
Background: Enteral nutrition (EN) supports many older and disabled Americans. This study describes the frequency and cost of acute care hospitalization with dehydration and/or malnutrition of Medicare beneficiaries receiving EN, focusing on those receiving home EN. Methods: Medicare 5% Standard Analytic Files were used to determine Medicare spending for EN supplies and the proportion and cost of beneficiaries receiving EN, specifically home EN, admitted to the hospital with dehydration and/or malnutrition. Results: In 2013, Medicare paid $370,549,760 to provide EN supplies for 125,440 beneficiaries, 55% of whom were also eligible for Medicaid. Acute care hospitalization with dehydration and/or malnutrition occurred in 43,180 beneficiaries receiving EN. The most common principal diagnoses were septicemia (21%), aspiration pneumonitis (9%), and pneumonia (5%). In beneficiaries receiving EN at home, >one‐third (37%) were admitted with dehydration and/or malnutrition during a mean observation interval of 231 ± 187 days. Admitted patients were usually hospitalized more than once with dehydration and/or malnutrition (1.73 ± 1.30 admissions) costing $23,579 ± 24,966 per admitted patient, totaling >$129,685,622 during a mean observation interval of 276 ± 187 days. Mortality in the year following enterostomy tube placement was significantly higher for admitted compared with nonadmitted patients (40% vs 33%; P = .05). Conclusion: Acute care hospitalizations with dehydration and/or malnutrition in Medicare beneficiaries receiving EN were common and expensive. Additional strategies to reduce these, with particular focus on vulnerable populations such as Medicaid‐eligible patients, are needed.  相似文献   
97.
Gabig  TG; Crean  CD; Mantel  PL; Rosli  R 《Blood》1995,85(3):804-811
Studies of neutrophil nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activation in a cell-free system showed that the low molecular-weight guanosine triphosphatase (GTPase) Rac was required, and that Rap1a may participate in activation of the catalytic complex. Full-length posttranslationally modified Rac2 was active, whereas only the 1-166 truncated form of Rap1a was functional in the cell-free system, and thus, clarification of the function of Rap1a and Rac2 in intact human phagocytes is needed to provide further insight into their roles as signal transducers from plasma membrane receptors. In the present studies, oligonucleotide-directed mutagenesis was used to introduce a series of mutations into human rap1a or rac2 in the mammalian expression vector pSR alpha neo. HL60 cells transfected with wild-type or mutated rac2 or rap1a cDNA constructs and control HL60 cells transfected with the pSR alpha neo vector containing no inserted cDNA were selected in G418-containing media, then subclones were isolated. Compared with the parent HL60 cells, each of the stable transfected cell lines differentiated similarly into neutrophil-like cells and expressed comparable levels of NADPH oxidase components p47- phox, p67-phox and gp91-phox. The differentiated vector control cell line produced O2. in response to receptor stimulation at rates that were not significantly different from parent HL60 cells. O2-. production by differentiated cell lines expressing mutated N17 Rap1a or N17 Rac2 dominant-negative proteins was inhibited, whereas O2-. production by the subline overexpressing wild-type Rap1a was increased by fourfold. O2-. production by the differentiated cell line expressing GTPase-defective V12 Rap1a was also significantly inhibited, a finding that is consistent with a requirement for cycling between guanosine diphosphate- and GTP-bound forms of Rap1a for continuous NADPH oxidase activation in intact neutrophils. A model is proposed in which Rac2 mediates assembly of the p47 and p67 oxidase components on the cytosolic face of the plasma membrane via cytoskeletal reorganization, whereas Rap1a functions downstream as the final activation switch involving direct physical interaction with the transmembrane flavocytochrome component of the NADPH oxidase.  相似文献   
98.
Percutaneous aortic valve replacement (PAVR) is an emerging therapy for nonsurgical patients with severe aortic stenosis (AS). We examined the role of transesophageal echocardiography (TEE) in PAVR. TEE was used initially to assess the native valve and aortic root, and served as a guide during PAVR. Following prosthetic valve deployment, TEE was used to assess valve function. Eleven patients aged 82 +/- 10 years with NYHA III-IV underwent PAVR. Periprocedural TEE gave immediate information on prosthetic position and function, LV function, mitral regurgitation, pericardium, and thoracic aorta anatomy. There was excellent visual agreement between fluoroscopic and TEE images of prosthetic positioning and deployment. TEE facilitated the detection and management of procedure-related complications. Compared with pre-PAVR, AV area (0.56 +/- 0.19 cm(2) vs. 1.3 +/- 0.4 cm(2); P < 0.001) and LVEF (49 +/- 17% vs. 56 +/- 11%; P < 0.001) increased. TEE provides key anatomical and functional information, and serves as a diagnostic guide for complications, which may arise during PAVR.  相似文献   
99.
This report describes an 85 year-old man who underwent percutaneous aortic valve replacement (PAVR). With a logistic euroSCORE of 37%, the patient had been refused surgical aortic valve replacement because of an unacceptably high peri-operative risk. During the PAVR procedure, severe resistance was encountered when advancing the 21 Fr delivery catheter through the left iliac artery despite pre-dilatation with a 7 mm balloon. Following this, PAVR was promptly achieved without difficulty, with excellent valve positioning, no peri-valvular leak and good hemodynamics. However, transesophageal echocardiography revealed a mobile echogenic mass within the outflow tract of the left ventricle. The mass was retrieved with a cardiac bioptome manipulated via the left femoral artery through a 9 Fr sheath. A right cerebral ischemic stroke manifested shortly after the post-procedure and the patient died on the fourth post-operative day. Post-mortem findings revealed a left subclavian artery occlusion by iliac vascular tissue. This report highlights the imperative for device-specific vascular access screening criteria and the need to minimize device size in order to safely accomplish PAVR.  相似文献   
100.
Unrelated donor marrow transplantation in children   总被引:3,自引:10,他引:3  
Eighty-eight children 0.5 to 17 years of age (median, 9 years of age) received an unrelated donor marrow transplant for treatment of chronic myeloid leukemia (CML; n = 16), acute lymphoblastic leukemia (ALL) in first or second remission (n = 15) or more advanced stage (n = 28), acute myeloid leukemia (AML; n = 13), or other hematologic diseases (n = 16) between June 1985 and April 1993. All patients were conditioned with cyclophosphamide and total body irradiation and received a combination of methotrexate and cyclosporine as graft-versus-host disease (GVHD) prophylaxis. Fourty-six patients received transplants from HLA-identical donors and 42 patients received transplants from donors who were minor-mismatched at one HLA-A or B or D/DRB1 locus. The Kaplan-Meier estimates of disease-free survival and relapse were 75% and 0% for patients with CML, 47% and 20% for ALL in first or second remission, 10% and 60% for ALL in relapse or third remission, 46% and 46% for AML in first remission (n = 1) or more advanced disease (n = 12), and 29% and 69% for other diseases. HLA disparity was not significantly associated with lower disease-free survival, but the results suggest more relapses in HLA-matched recipients and there was significantly more transplant-related mortality in mismatched recipients (51% v 24%, P = .04). Most deaths were due to infections associated with acuteor chronic GVHD and occurred within the first 2 years after transplantation. Granulocyte engraftment occurred in all evaluable patients. Sixty-three percent of HLA-matched and 57% of HLA- mismatched recipients were discharged home disease-free at a median of 98 and 103 days, respectively, after transplantation (P = not significant [NS]). The incidence of grades II-IV acute GVHD was 83% in HLA-matched and 98% in HLA-mismatched recipients (P = .009). The incidence of chronic GVHD was 60% in HLA-matched and 69% in HLA- mismatched recipients (P = NS). One or multiple late adverse events such as cataracts, osteonecrosis of the hip or knee, restrictive or obstructive pulmonary disease, and hypothyroidism have occurred in 11 of 33 (33%) surviving patients. Immunosuppression was discontinued in 58% of surviving patients, including all 12 patients surviving more than 3.2 years, all of whom have a Lansky or Karnofsky score of 100%.(ABSTRACT TRUNCATED AT 400 WORDS)  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