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   1763篇
  免费   84篇
  国内免费   56篇
耳鼻咽喉   6篇
儿科学   84篇
妇产科学   12篇
基础医学   200篇
口腔科学   25篇
临床医学   168篇
内科学   386篇
皮肤病学   66篇
神经病学   42篇
特种医学   317篇
外科学   325篇
综合类   32篇
一般理论   1篇
预防医学   54篇
眼科学   10篇
药学   70篇
中国医学   17篇
肿瘤学   88篇
  2023年   7篇
  2021年   13篇
  2020年   13篇
  2019年   11篇
  2018年   24篇
  2017年   7篇
  2016年   12篇
  2015年   20篇
  2014年   18篇
  2013年   48篇
  2012年   44篇
  2011年   28篇
  2010年   49篇
  2009年   72篇
  2008年   34篇
  2007年   74篇
  2006年   55篇
  2005年   40篇
  2004年   48篇
  2003年   32篇
  2002年   36篇
  2001年   43篇
  2000年   38篇
  1999年   40篇
  1998年   76篇
  1997年   90篇
  1996年   114篇
  1995年   68篇
  1994年   61篇
  1993年   63篇
  1992年   39篇
  1991年   33篇
  1990年   49篇
  1989年   60篇
  1988年   48篇
  1987年   56篇
  1986年   55篇
  1985年   51篇
  1984年   19篇
  1983年   24篇
  1982年   19篇
  1981年   14篇
  1980年   15篇
  1979年   15篇
  1978年   22篇
  1977年   18篇
  1976年   18篇
  1975年   17篇
  1974年   10篇
  1970年   10篇
排序方式: 共有1903条查询结果,搜索用时 0 毫秒
81.
This article focuses on children's participation in disaster risk reduction.It draws on a 2018 study done in New Zealand with 33 school children who conducted p...  相似文献   
82.
小鼠皮肤超氧化物歧化酶活性与枸杞多糖的干预   总被引:1,自引:0,他引:1  
目的:观察枸杞多糖对皮肤胶原代谢和自由基产生的影响,探讨其抗皮肤衰老的作用。方法:实验于2005-06/2006-05在广东医学院整形外科研究所完成。①实验材料:清洁级昆明小鼠60只,月龄2个月,体质量16~24g,雌雄各半。②实验分组:将小鼠随机分为正常对照组、衰老模型组和抗衰老模型组,每组20只。③实验干预:模型组每日用D-半乳糖溶液皮下注射制造衰老模型,用量和时间为80mg/(kg·d)7d,120mg/(kg·d)14d,140mg/(kg·d)14d,180mg/(kg·d)7d。正常对照组每日注射同体积的生理盐水。抗衰老模型组在注射D-半乳糖期间以枸杞多糖灌胃,剂量为20mg/(kg·d),正常对照组和衰老组则以同体积的生理盐水代之灌胃。④实验评估:42d后切取小鼠颈背部皮肤,测定超氧化物歧化酶活力、羟脯氨酸和丙二醛含量。结果:56只小鼠进入结果分析(4只死亡)。①小鼠皮肤超氧化物歧化酶活力:与正常对照组相比,衰老组和抗衰老组小鼠皮肤超氧化物歧化酶活力降低,差异有显著性意义(P<0.01);抗衰老组与衰老模型组比较,超氧化物歧化酶活力增加,差异有显著性意义(P<0.01)。②与正常对照组相比,衰老组和抗衰老组小鼠皮肤羟脯氨酸和丙二醛含量增加,差异有显著性意义(P<0.01);抗衰老组与衰老组比较,羟脯氨酸和丙二醛含量均降低,差异有显著性意义(P<0.01)。结论:枸杞多糖改善皮肤老化的作用与提高小鼠皮肤超氧化物歧化酶活力,降低羟脯氨酸、丙二醛含量,影响胶原代谢有关。  相似文献   
83.
目的:观察白藜芦醇对一次性力竭游泳大鼠肝脏组织的作用及发挥作用的最佳口服剂量。方法:实验于2006-05/07在成都体育学院运动医学系动物实验室完成。①实验分组:选取雄性SD大鼠70只,随机分为7组,每组10只,分别为安静对照组,运动对照组,运动 15mg/kg白藜芦醇组,运动 50mg/kg白藜芦醇组,运动 100mg/kg白藜芦醇组,运动 200mg/kg白藜芦醇组,运动 300mg/kg白藜芦醇组。②实验干预:不同剂量白藜芦醇组每天灌胃15,50,100,200,300mg/kg白藜芦醇,安静对照组和运动对照组分别灌胃相同体积的溶媒(二甲亚砜 生理盐水),连续5周。末次给予实验用样品1h后,各运动组每只鼠尾跟部负荷3%体质量铅皮,置于水深50cm、水温(31±1)℃游泳槽中游泳。游泳力竭后即刻,股动脉取血并迅速取出肝组织。③指标检测:赖氏比色法测定血清中谷丙转氨酶活性;邻苯三酚自氧化法测定肝组织超氧化物歧化酶活性;硫代巴比妥酸法测定肝组织丙二醛含量。结果:纳入动物70只,均进入结果分析。①血清谷丙转氨酶活性和肝组织中丙二醛含量:运动对照组显著高于安静对照组,不同剂量白藜芦醇组低于运动对照组(P<0.05或P<0.01)。运动 100,200,300mg/kg白藜芦醇组低于运动 15,50mg/kg白藜芦醇组[谷丙转氨酶活性:(972.36±121.86),(944.36±105.35),(888.34±88.68),(1773.52±89.35),(1377.78±27.01)nkat/L,P<0.01;丙二醛含量:(7.90±2.56),(7.69±3.69),(7.13±2.62),(19.90±2.21),(12.16±1.78)μmol/g,P<0.05]。100,200,300mg/kg白藜芦醇组间差异无显著性。②肝脏组织中超氧化物歧化酶活性:运动对照组显著低于安静对照组,不同剂量白藜芦醇组高于运动对照组(P<0.05或P<0.01)。运动 100,200,300mg/kg白藜芦醇组高于15,50mg/kg白藜芦醇组[(2325.80±163.37),(2379.14±121.86),(2447.16±89.18),(1096.05±120.19),(1514.64±28.17)μkat/g,P<0.01]。结论:①白藜芦醇对力竭性运动大鼠肝脏组织具有保护作用。②100,200,300mg/kg白藜芦醇对肝脏组织发挥保护作用效果优于15,50mg/kg,建议使用100mg/kg白藜芦醇就能达到理想效果。  相似文献   
84.
BACKGROUND: Local residual tumor predicts poor patient survival after resection for colorectal cancer. The aim of this study was to determine the prevalence of residual tumor in a line of resection in a large prospective series and to identify other pathology variables that may influence survival in the absence of distant metastases in such patients. STUDY DESIGN: This study was based on all patients who had a resection for colorectal cancer at Concord Hospital between 1971 and 2001. Patients were followed up annually until death or December 2002. Survival analysis used the Kaplan-Meier method and log rank test. Proportional hazards regression was used in multivariate modeling. RESULTS: The overall prevalence of residual tumor in a line of resection was 5.9%. Of 12 pathology variables examined, only high grade and apical node metastasis were independently associated with survival in the subset of 120 patients with residual tumor in a line of resection but without distant metastases. The 2-year survival rate for patients with neither of these adverse features was 46.4% (95% CI, 31.7% to 59.9%) as compared with only 7.7% (CI, 0.5% to 29.2%) in those who had both. CONCLUSIONS: These results show that presence of local residual tumor after colorectal cancer resection does not carry a universally poor prognosis. Two specific histopathologic features independently associated with diminished survival were identified.  相似文献   
85.
The detection and quantitation of apoptotic cells is becoming increasingly important in the investigation of the role of apoptosis in cellular proliferation and differentiation. The pathogenesis of hematologic disorders such as aplastic anemia and the development of neoplasia are believed to involve dysregulation of apoptosis. To quantitate accurately the proportion of apoptosis cells within different cell types of a heterogeneous cell population such as blood or bone marrow, a method is required that combines the analysis of large numbers of cells with concurrent immunophenotyping of cell surface antigens. In this study, we have evaluated such a method using the fluorescent DNA binding agent, 7-amino actinomycin D (7AAD), to stain three diverse human cell lines, induced to undergo apoptosis by three different stimuli. Flow cytometric analysis defines three populations on the basis of 7AAD fluorescence and forward light scatter. We have shown by cell sorting and subsequent morphological assessment and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labeling that the populations defined by 7AAD represent live, apoptotic, and late-apoptotic/dead cells. This method is quick, simple, reproducible, and cheap and will be a valuable tool in the investigation of the role of apoptosis in normal physiology and in disease states.  相似文献   
86.
87.
To propose minimal important differences (MID) for the Migraine-Specific Quality of Life Questionnaire version 2.1 (MSQ v2.1). To our knowledge (to date), no published MID values exist for the MSQ v2.1 in any population. Analyses were performed on data from two pivotal clinical trials of topiramate for migraine prevention ( n  = 916), as well as from the QualityMetric National Headache Survey ( n  = 1016). Analyses included both distribution- and anchor-based MID techniques as well as group- and individual-level MID values. Group-level anchor-based MID values ranged from 3.2 [Role Restrictive domain (RR)] to 7.5 [Emotional Functioning domain (EF)], setting the minimum level of appropriate MID (which can also aid with power analysis). Individual-level distribution-based MID values resulted in highly similar estimates from two large databases: median MID of 8.5 for RR, 9.2 for Role Preventive (RP) and 12.0 for EF. Finally, individual-level anchor-based MID values ranged from 5.0 (RR and RP domains) to 10.6 (EF). For group-level purposes of calculating power for future studies, an MID of 3.2, 4.6 and 7.5 for RR, RP and EF is recommended. For within-group analyses for analysing clinical trial efficacy of each patient's change with responder analyses, 5 points is necessary for RR. For RP and EF, ranges are recommended: 5.0 to 7.9 for RP and 8.0 to 10.6 for EF. These latter two domains tend to have more error in the MID, and thus a sensitivity analysis with both ends of the range should be used to confirm significant differences in responder analyses.  相似文献   
88.
89.
Three recent publications have reported the development of erythema multiforme and Stevens-Johnson syndrome in patients receiving cranial irradiation and sodium phenytoin. Some authors have recommended that patients receiving whole brain radiation therapy and who have had seizures should not be prescribed phenytoin but an alternative anticonvulsant. This article reviews the current literature pertaining to the development of this potentially lethal complication in patients receiving whole brain radiation and phenytoin, with reference to the single recorded case of Stevens-Johnson syndrome in a patient receiving cranial irradiation and phenytoin in Auckland, New Zealand. While the clinical picture in the 16 patients reported in the literature and the current case report differed from the classical form of erythema multiforme, a similar pattern of presentation and outcome appeared in all patients reviewed, suggesting that the combination of phenytoin, cranial irradiation and the gradual reduction of concomitant steroids seem to lead to the development of erythema multiforme and/or Stevens-Johnson syndrome. The data presented, although sparse, suggest that phenytoin should not be prescribed in patients receiving cranial irradiation.  相似文献   
90.
Two cases with the clinical presentation of peritonitis and a 9 year-old girl with ovarian torsion are reported: a 2 year-old girl with paroxistic abdominal pain and occlusive syndrome. Ultrasonography was of main interest in that situation. The necrotized ovary was extracted at intervention in both cases; histological data did not allow to distinguish the torsion on an hemangiomatous ovary from the torsion of an healthy ovary, which represents an exceptional feature.  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