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   530篇
  免费   16篇
  国内免费   9篇
耳鼻咽喉   1篇
儿科学   47篇
妇产科学   9篇
基础医学   49篇
口腔科学   9篇
临床医学   44篇
内科学   148篇
皮肤病学   10篇
神经病学   4篇
特种医学   133篇
外科学   35篇
综合类   10篇
预防医学   12篇
眼科学   2篇
药学   20篇
  1篇
中国医学   6篇
肿瘤学   15篇
  2022年   3篇
  2021年   4篇
  2018年   5篇
  2017年   5篇
  2016年   3篇
  2015年   5篇
  2014年   11篇
  2013年   13篇
  2012年   10篇
  2011年   5篇
  2010年   24篇
  2009年   21篇
  2008年   13篇
  2007年   15篇
  2006年   11篇
  2005年   8篇
  2004年   8篇
  2003年   11篇
  2002年   3篇
  2001年   13篇
  2000年   8篇
  1999年   6篇
  1998年   27篇
  1997年   27篇
  1996年   40篇
  1995年   36篇
  1994年   35篇
  1993年   18篇
  1992年   2篇
  1991年   10篇
  1990年   4篇
  1989年   18篇
  1988年   23篇
  1987年   16篇
  1986年   13篇
  1985年   14篇
  1984年   10篇
  1983年   7篇
  1982年   6篇
  1981年   7篇
  1980年   9篇
  1979年   2篇
  1978年   3篇
  1977年   7篇
  1976年   5篇
  1975年   4篇
  1973年   2篇
  1970年   1篇
  1965年   1篇
  1959年   1篇
排序方式: 共有555条查询结果,搜索用时 15 毫秒
551.
From March 2007 to September 2009, we have screened with echocardiography a total of 6,502 pregnant women for fetal heart disease. We found three cases of fetal ventricular aneurysm. The relatively large size of the aneurysm in these three cases was clearly visible under standard four‐chamber view. Two were right ventricular aneurysms arisen from the ventricular free wall, and both showed characteristics of true aneurysm with a thin wall and a large communication with the ventricular chamber. Color Doppler showed passive movement of aneurysm during right ventricle contraction. The third case was a large left ventricular aneurysm outpouching from a small opening of the left ventricular wall close to the apical region. © 2014 Wiley Periodicals, Inc. J Clin Ultrasound 43 :257–261, 2015  相似文献   
552.
Coronary artery disease (CAD) has a strong genetic component, but is also greatly influenced by environmental factors such as diet and smoking, and disorders such as diabetes mellitus and hypertension. This interaction makes prediction of CAD risk generally difficult. However, in familial hypercholesterolaemia (FH), risk of early CAD is considerably increased by the mutation of a single gene, and genetic testing may be appropriate. We summarize current knowledge concerning DNA-based tests in the identification and management of FH, and propose specific recommendations for genetic testing and further research. The major value of DNA tests for FH is in genetic tracing programs to identify and treat affected individuals. DNA testing is appropriate for: (a) diagnosis of FH when physical signs or family history are equivocal or absent (important given the increased risk of CAD associated with FH compared to other hypercholesterolaemias); (b) detection of a mutation causing FH in immediate family members (particularly children) where there is a family history of premature CAD. A positive DNA-based test for a mutation is especially useful in children, in whom plasma lipid levels may not be diagnostic. Current clinical practice is to test relatives for raised cholesterol. Testing for mutation carriers in distant relatives, although feasible, is not currently recommended. Research projects should now be started to address two issues: (i) whether genetic tests for FH better predict clinical outcome than does measurement of plasma lipid levels; (ii) whether genetic testing for FH confers overall benefit both to the patient and their relatives, and to the NHS. Answers to these questions will guide the subsequent development and implementation of genetic tests for CAD risk in general, if and when the considerably more complex genetic causes of CAD are identified.   相似文献   
553.
BACKGROUND : Prestorage white cell (WBC) reduction in blood components may decrease the incidence of adverse reactions and improve component quality. A bottom-and-top system with an integral third-generation WBC- reduction filter has been studied. STUDY DESIGN AND METHODS : Whole blood was collected from 30 healthy donors: from 20 by using a blood container system with an integral filter and from 10 controls by using a standard blood container system. Ten test units were buffy coat- depleted, stored for 72 hours at 4 degrees C, and then filtered, while an additional 10 test units were buffy coat-depleted and filtered at room temperature within 8 hours of collection. All units were stored at 4 degrees C for 42 days and sampled weekly. RESULTS : The mean WBC content of the 72-hour, 4 degrees C units was 0.33 × 10(6), that of the room-temperature units was 2.6 × 10(6), and that of the buffy coat- depleted controls was 460 × 10(6) (p < 0.0005). No significant differences were found among lactate, glucose, sodium, potassium, and plasma hemoglobin levels in the three groups. ATP and 2,3 DPG levels were significantly better preserved in control units than in 72-hour, 4 degrees C units (p = 0.016 and p = 0.032, respectively), but not better than in the room-temperature units. Significant differences were observed between pH values in filtered units and both groups of test units (p = 0.016). In biologic terms however, these differences were small. Red cells from an additional eight healthy volunteer donors were processed by an 8-hour room-temperature method and stored for 35 days. Studies in vivo 24-hour recovery of autologous red cells were performed by transfusing a radiolabeled (51Cr plus 131I-albumin) aliquot after 35 days' storage. Good recovery (mean > 80%) was found by both the single- and double-isotope-label methods. Recovery was significantly greater when calculated by the single-isotope method (p = 0.02). CONCLUSION : The combination of buffy coat removal and filtration in the blood container system with an integral filter achieved effective WBC reduction (> or = 3 log10 reduction from whole blood) without biologically significant detriment to in vitro or in vivo storage values.  相似文献   
554.
目的:采用两种改良方法体外分离培养脐血间充质干细胞,并观察其成骨分化能力。方法:实验于2006-05/09在上海交通大学医学院附属第九人民医院骨与关节中心细胞实验室完成。①所用28份脐血标本由复旦大学医学院附属妇产科医院提供,取自足月健康顺产新生儿,产妇和家属均书面同意,实验经医学伦理委员会批准。②采集28份脐血标本,50~90mL/份,枸橼酸抗凝。采集后12h内密度梯度离心法分离出单个核细胞,接种于100mm×20mm培养皿中,细胞浓度为1×1010L-1,置于含体积分数为0.1胎牛血清的α-MEM培养液中原代培养,5~7d后半量换液,后每隔3~4d全量换液一次。③细胞贴壁后,分两组予以改良培养。改良1组10份,当培养皿底圆形巨核细胞融合、梭形成纤维样细胞脱落时将细胞悬液移入新的培养皿中培养;改良2组18份,待培养皿底圆形巨核细胞渐渐占据优势时,将培养基更换为含体积分数为0.15小牛血清的α-MEM,当圆形巨核细胞大部脱落后换回含体积分数为0.1胎牛血清的α-MEM培养基。成纤维样细胞融合至80%~90%时胰酶消化,按1∶2或1∶3传代培养。④显微镜下观察脐血间充质干细胞的形态。取第5代脐血间充质干细胞,采用流式细胞仪测定细胞免疫表型,以碱性磷酸酶法检测成骨分化能力。结果:①28份脐血间充质干细胞中,共20份原代培养中出现贴壁细胞(改良1组6份,改良2组14份),其中13份培养出能融合且可稳定传代的成纤维样细胞(改良1组4份,改良2组9份),成功率46.4%。②原代培养5~7d后贴壁细胞呈梭形成纤维样细胞和圆形巨核细胞。改良1组与2组于原代培养5周可见成纤维样细胞集落,细胞形态与骨髓间充质干细胞相似,呈较均一的长梭形,传至22代形态无明显变化。③可强烈表达CD29、CD105等间充质干细胞表面标志,而不表达CD34、CD45和CD106等造血干细胞和内皮细胞标志。④成骨诱导1周,脐血间充质干细胞可分化为成骨细胞,碱性磷酸酶染色呈阳性。结论:脐血中存在的单个核细胞经过改良培养后,可提高脐血间充质干细胞的培养成功率。脐血间充质干细胞具有与其他来源的单个核细胞类似的表型及成骨分化潜能,且易于体外扩增、传代稳定。  相似文献   
555.
目的:观察循环抗阻训练对绝经后妇女体质的影响。方法:调查于2005-03/12在邵阳学院运动康复中心进行。年龄50~65岁,自然绝经1年以上的绝经后妇女。未经激素替代治疗,身体基本健康,不吸烟,无心脑血管疾病、糖尿病,所有受试者试验前进行常规体检及辅助检查,未见异常。血总胆固醇在6.50mmol/L以下,三酰甘油在2.50mmol/L以下,体脂率在35%以下。所有受试者保持平时的饮食习惯及一般的体力活动。不重复随机数法分为抗阻训练组和对照组两组,每组12人。两组实验前的各指标比较无明显差异。抗阻训练组应用器械和在训练机上进行躯干及上下肢大肌群的练习。每次运动包括3个循环,每1循环包括12节运动,每节运动包括在30~45s内做8次收缩,各节运动间休息15~30s,每个循环间休息2min。训练强度:为1次收缩最大负荷的80%。每周二、四、六训练,3次/周。每4周测1次最大收缩力,以监测训练进程和确定新的运动负荷。实验期间严格进行医务监督并遵循循序渐进原则。12周的抗阻训练后测定身高、体质量、心率、血压、腰围、臀围、体脂率、最大吸氧量、血糖、血脂。结果:24名绝经后妇女均进入结果分析。①抗阻训练组训练后的腰围、臀围、体脂率、安静收缩压与训练前及对照组比较,均显著降低或减少[训练后:(74.4±5.5)cm,(92.0±5.0)cm,(25.7±3.4)%,(105.4±17.0)mmHg;训练前:(76.8±5.2)cm,(94.1±5.1)cm,(27.4±3.5)%,(112.7±14.0)mmHg;对照组:(76.1±4.6)cm,(93.0±5.2)cm,(27.1±3.7)%,(114.0±15.1)mmHg,P<0.01,P<0.05]。握力和背肌力较训练前及对照组明显增加[训练后:(27.9±2.5),(64.7±3.6)kg;训练前:(23.6±2.5),(61.6±4.2)kg;对照组:(23.9±1.6),(59.2±3.3)kg,P<0.01]。②抗阻训练组训练后三酰甘油较训练前及对照组下降[(1.42±0.13),(1.63±0.14),(1.63±0.19)mmol/L,P<0.01,P<0.05],低密度脂蛋白胆固醇较训练前降低[(3.14±0.44),(3.26±0.56),(3.10±0.47)mmol/L,P<0.05],高密度脂蛋白胆固醇较训练前及对照组显著升高[(1.44±0.24),(1.26±0.25),(1.23±0.23)mmol/L,P<0.01,P<0.05]。结论:循环抗阻训练可安全有效地改善绝经后妇女的体质,是预防和治疗冠心病的有效措施。  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