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   1167篇
  免费   89篇
  国内免费   25篇
耳鼻咽喉   4篇
儿科学   50篇
妇产科学   21篇
基础医学   106篇
口腔科学   96篇
临床医学   150篇
内科学   265篇
皮肤病学   46篇
神经病学   70篇
特种医学   123篇
外科学   87篇
综合类   92篇
一般理论   2篇
预防医学   48篇
眼科学   20篇
药学   52篇
中国医学   1篇
肿瘤学   48篇
  2021年   9篇
  2020年   8篇
  2019年   9篇
  2018年   11篇
  2017年   8篇
  2016年   18篇
  2015年   14篇
  2014年   23篇
  2013年   69篇
  2012年   14篇
  2011年   22篇
  2010年   42篇
  2009年   41篇
  2008年   25篇
  2007年   48篇
  2006年   31篇
  2005年   28篇
  2004年   26篇
  2003年   22篇
  2002年   18篇
  2001年   26篇
  2000年   21篇
  1999年   32篇
  1998年   55篇
  1997年   52篇
  1996年   38篇
  1995年   29篇
  1994年   37篇
  1993年   39篇
  1992年   14篇
  1991年   27篇
  1990年   23篇
  1989年   47篇
  1988年   36篇
  1987年   37篇
  1986年   21篇
  1985年   22篇
  1984年   19篇
  1983年   11篇
  1982年   14篇
  1981年   12篇
  1980年   12篇
  1978年   10篇
  1977年   7篇
  1976年   8篇
  1975年   9篇
  1972年   9篇
  1966年   7篇
  1963年   6篇
  1941年   11篇
排序方式: 共有1281条查询结果,搜索用时 15 毫秒
61.
We report the final results of the trial comparing the Amplatz thrombectomy device (ATD) with surgical thromboembolectomy (ST) to declot thrombosed dialysis access grafts (DAG). The study population consisted of 174 DAG, 109 of which were randomized to mechanical thrombectomy using the ATD and 65 of which were randomized to conventional surgical thromboembolectomy. Forty grafts were re-enrolled in the trial when they failed beyond the 90 days follow-up after the initial treatment. Thirty-one were re-enrolled for mechanical thrombectomy and nine were re-enrolled for surgical thrombectomy, resulting in a total of 140 ATD procedures and 74 surgical thromboembolectomy. Immediate thrombectomy success was defined as greater than 90% thrombus removal followed by the ability to dialyze after treatment, and analysis of long term success based on graft patency at 30 and 90 days, with successful dialysis. Immediate thrombectomy success with the ATD procedure was achieved in 79.2% and with ST in 73.4%. Patency of the graft, with successful dialysis, at 30 days with the ATD procedure was 79.2% and with ST was 73.4%. Patency of the graft, with successful dialysis, at 90 days with the ATD procedure was 75.2% and with ST was 67.8%. The data collected in this study provided a prospective comparison of mechanical thrombectomy with the ATD and ST performance in thrombosed DAG. The results of the performance of both methods were comparable. No statistically significant differences were seen.List of Investigators: Carol C. Steenson (Department of Radiology, VA Medical Center, Minneapolis, MN), Renan Uflacker (Interventional Radiology, Medical University of South Carolina, Charleston, SC), Richard J. Gray (Interventional Radiology, Washington Hospital Center, Washington, DC), George A. Fueredi (St Marys Hospital, Milwaukee, WI), Michael P. Hickman (Vascular and Interventional Radiology, St Josephs Regional Health Center, Hot Springs, AR), Robert Smith (Interventional Radiology, Tulane University Medical Center, New Orleans, LA), Paul Kamin (Department of Radiology, Los Alamitos Medical Center, Los Alamitos, CA), Mac Dryjski (Department of Surgery, Millard Filmore Hospital, Buffalo, NY), Michael Bettman (Vascular and Interventional Radiology, Dartmouth-Hitchcock Medical Center, Lebanon, NH).  相似文献   
62.
63.
RMP-7, a bradykinin analog, temporarily increases the permeability of the blood-brain tumor barrier to chemotherapy drugs like carboplatin. We conducted a randomized, controlled trial of carboplatin and RMP-7 versus carboplatin and placebo in patients with recurrent malignant glioma. The primary outcome measure was time to tumor progression (TTP). Adults with recurrent glioblastoma multiforme or anaplastic glioma were randomized in a 1:1 ratio to receive carboplatin and either RMP-7 or placebo. Radiation therapy had failed in all patients, and they may have received prior chemotherapy. Carboplatin (dosed to achieve an area under the curve of 5 mg/ml x time for patients who had received prior chemotherapy, or 7 mg/ml x time for those who had not) was given intravenously every 4 weeks, followed by intravenous infusion of either RMP-7 or placebo (300 ng/kg). TTP, tumor response, neuropsychological assessments, functional independence, and quality of life assessments were analyzed every 4 weeks. There were 122 patients enrolled, 62 in the RMP-7 and carboplatin group and 60 in the placebo and carboplatin group. Median TTP was 9.7 weeks (95% CI, 8.3-12.6 weeks) for the RMP-7 and carboplatin group and 8.0 weeks (95% CI, 7.4-12.6 weeks) for the placebo and carboplatin group. Median survival times were 26.9 weeks (95% CI, 21.3-37.6 weeks) for the RMP-7 group and 19.9 weeks (95% CI, 15.0-31.3 weeks) for the placebo group. No differences were noted for time to worsening of neuropsychological assessments, functional independence, or quality of life assessments. The use of RMP-7 had no effect on the pharmacokinetics or toxicity of carboplatin. At the dose and schedule used in this trial, RMP-7 did not improve the efficacy of carboplatin. Recent preclinical pharmacokinetic modeling of RMP-7 suggests that higher doses of RMP-7 may be required to increase carboplatin delivery to tumor.  相似文献   
64.
Background Hydatid disease is rare in Ireland and its incidence and prevalence are unknown. Most cases are diagnosed by a combination of clinical findings, morphological features on imaging and by serological testing. Aims We describe an Irish case of pulmonary hydatid disease detected at bronchoscopy by bronchoalveolar lavage, and discuss the diagnosis and treatment of the disorder.  相似文献   
65.
66.
A history of pet contact and/or apparent clinical sensitivity was obtained in 65 (55%) of 118 unselected asthmatic children. These 65 children were skin tested and their sera examined for specific IgE using the radioallergosorbent test. Those children who had apparent clinical sensitivities had larger skin test reactions and were more likely to have positive specific IgE results than those without apparent sensitivities. Positive skin tests were very common (80%), but the larger the skin test reaction (weal diameter greater than 4 mm diameter) the more likely was there to be a positive history or a positive specific IgE result. Hence a large skin test reaction can provide a helpful pointer to animal allergy of clinical importance. Commercially available animal extracts have limitations for diagnostic tests. A questionnaire survey of 150 day schools emphasized the potential opportunities for contact with animal allergens at school.  相似文献   
67.
Southeast Asian ovalocytosis (SAO) is an asymptomatic trait characterized by rigid, poorly deformable red cells that resist invasion by several strains of malaria parasites. The underlying molecular genetic defect involves simple heterozygous state for a mutant band 3 protein, which contains a deletion of amino acids 400 through 408, linked with a Lys 56-to-Glu substitution (band 3-Memphis polymorphism). To elucidate the contribution of the mutant SAO band 3 protein to increased SAO red blood cell (RBC) rigidity, we examined the participation of the mutant SAO band 3 protein in increased band 3 attachment to the skeleton and band 3 oligomerization. We found first that SAO RBC skeletons retained more band 3 than normal cells and that this increased retention preferentially involved the mutant SAO band 3 protein. Second, SAO RBCs contained a higher percentage of band 3 oligomer-ankyrin complexes than normal cells, and these oligomers were preferentially enriched by the mutant SAO protein. At the ultrastructural level, the increased oligomer formation of SAO RBCs was reflected by stacking of band 3-containing intramembrane particles (IMP) into longitudinal strands. The IMP stacking was not reversed by treating SAO RBCs in alkaline pH (pH 11), which is known to weaken ankyrin-band 3 interactions, or by removing the cytoplasmic domain of band 3 from SAO membranes with trypsin. Finally, we found that band 3 protein in intact SAO RBCs exhibited a markedly decreased rotational mobility, presumably reflecting the increased oligomerization and the membrane skeletal association of the SAO band 3 protein. We propose that the mutant SAO band 3 has an increased propensity to form oligomers, which appear as longitudinal strands of IMP and exhibit increased association with membrane skeleton. This band 3 oligomerization underlies the increase in membrane rigidity by precluding membrane skeletal extension, which is necessary for membrane deformation.  相似文献   
68.
维生素K3粉末降解动力学   总被引:1,自引:0,他引:1  
在温度为50~90℃,相对湿度为50~93%范围内,维生素K3的变色速率方程为—dR/dt=kRR,降解速率方程为d(Co—c)/dt=kC(co—c)1/2,光解速率方程为—dR/dt=kP(Ro—R)-1。kRC与热力学温度T和相对湿度RH的关系通式为k=k′exp(—EA/RT)exp(m′RH)。在实验温度和湿度范围内,变色和降解的表观活化能平均值分别为105.51和130.72 kJ/mol。  相似文献   
69.
Head injury in child abuse: evaluation with MR imaging   总被引:3,自引:0,他引:3  
To evaluate the usefulness of magnetic resonance (MR) imaging in the diagnosis of head injury in child abuse, the authors compared the findings at head MR imaging and computed tomography (CT) in 19 abused children. Subdural hematomas (15 cases), cortical contusions (six cases), and shearing injuries (five cases) were demonstrated to particular advantage with MR imaging. CT remained superior in the detection of subarachnoid hemorrhage. MR imaging appears to be valuable in the assessment of patients with suspected intracranial injury due to child abuse.  相似文献   
70.
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