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   18082篇
  免费   1063篇
  国内免费   358篇
耳鼻咽喉   156篇
儿科学   475篇
妇产科学   142篇
基础医学   1482篇
口腔科学   221篇
临床医学   1712篇
内科学   2484篇
皮肤病学   101篇
神经病学   523篇
特种医学   553篇
外科学   3733篇
综合类   2382篇
现状与发展   1篇
预防医学   1982篇
眼科学   49篇
药学   1918篇
  13篇
中国医学   1033篇
肿瘤学   543篇
  2024年   36篇
  2023年   337篇
  2022年   719篇
  2021年   904篇
  2020年   721篇
  2019年   678篇
  2018年   677篇
  2017年   647篇
  2016年   623篇
  2015年   607篇
  2014年   1260篇
  2013年   1256篇
  2012年   1087篇
  2011年   1175篇
  2010年   862篇
  2009年   894篇
  2008年   871篇
  2007年   913篇
  2006年   739篇
  2005年   619篇
  2004年   494篇
  2003年   382篇
  2002年   321篇
  2001年   292篇
  2000年   241篇
  1999年   210篇
  1998年   160篇
  1997年   168篇
  1996年   146篇
  1995年   143篇
  1994年   128篇
  1993年   99篇
  1992年   103篇
  1991年   101篇
  1990年   89篇
  1989年   73篇
  1988年   79篇
  1987年   71篇
  1986年   55篇
  1985年   71篇
  1984年   70篇
  1983年   64篇
  1982年   62篇
  1981年   44篇
  1980年   48篇
  1979年   37篇
  1978年   23篇
  1977年   26篇
  1975年   16篇
  1971年   12篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Our previous studies demonstrated that sodium glucose cotransporter 1 (SGLT-1) was induced in the remnant ileum of total colectomized rats via the action of factors other than hyperaldosteronism. The aim of the present study was to clarify whether fecal stream is required for the enhancement of SGLT-1-mediated sodium transport. Twenty-seven pairs of ileal tissues were obtained from the proximal and distal side, respectively, of loop ileostomy after total proctocolectomy. Mucosae were mounted in an Ussing chamber to evaluate glucose-coupled sodium transport. Levels of SGLT-1 mRNA in proximal and distal mucosae were compared by Northern blotting. Villous height and crypt depth were measured to test for correlations between mucosal structure and SGLT-1-mediated sodium transport or mRNA expression levels. Both glucose-coupled sodium transport and expression of SGLT-1 mRNA were significantly lower in distal mucosae relative to proximal mucosae. In distal mucosae, villous height, but not crypt depth, was significantly lower than in proximal mucosae, demonstrating a positive correlation between villous height and SGLT-1 function and expression. Comparative studies of proximal and distal mucosae demonstrated that in addition to hormonal changes, fecal stream is required for full induction of the sodium transport system (which includes SGLT-1-mediated transport) in the remnant ileum following total proctocolectomy. Presented in part at the Forty-Sixth Annual Meeting of The Society for Surgery of the Alimentary Tract, Chicago, Illinois, May 14–19, 2005 (poster presentation). This work was supported by Grants-in-Aid for Scientific Research 10557118 and 14657295 from the Ministry of Education, Science and Culture of Japan to K. Fukushima, and by Kanae Foundation to K. Fukushima.  相似文献   
102.
Day-to-day variations in serum iron, serum iron binding capacity, serum ferritin and erythrocyte protoporphyrin were determined on 2 successive days in 48 patients with anaemia. The correlation coefficients between the paired determinations were 0.86, 0.89, 0.95 and 0.95, and the day-to-day coefficients of variation (in per cent) were 33, 11, 12 and 13 for serum iron, serum iron binding capacity, erythrocyte protoporphyrin and serum ferritin, respectively. Thus, in patients with anaemia, day-to-day variations in serum iron, serum iron binding capacity, erythrocyte protoporphyrin and serum ferritin are at least as high as in healthy controls. The results indicate important limitations in the use, particularly, of serum iron in the clinical investigation of anaemia.  相似文献   
103.
目的探讨脑利钠肽(BNP)在评价功能性单心室患者行全腔静脉-肺动脉连接术(TCPC)后心功能中的价值及其意义。方法选择2004年4~11月间连续在我科随访的TCPC后患者11例(TCPC组),男7例,女4例;年龄8.2±4.1岁;随访时间2.1±1.6年。按照改良R oss标准对临床心功能评分。采集外周静脉血3m l,用酶标免疫法测定血浆BNP浓度。其中6例同期用磁共振成像(M R I)测定心功能,对BNP做相关因素分析。9人健康儿童作为正常对照(对照组)。结果(1)TCPC组血浆BNP水平为400pg/m l(IQR 200-690),较对照组的110 pg/m l(IQR 90-190)增高(P=0.003);(2)M R I测定结果:TCPC组6例患者舒张期末容量指数为65.76±8.65 m l/m2,收缩期末容量指数为31.90±6.36 m l/m2,心搏出量指数为39.09±11.76 m l/m2,射血分数(EF)为0.52±0.06,心脏指数(C I)为2.38±0.58 L/m in.m2,心肌质量指数为103.49±21.57 g/m2,心肌质量/心室舒张期末容量为1.57±0.24;(3)TCPC组BNP水平与手术时年龄呈明显正相关(r=0.632,P=0.041);BNP水平与上述M R I指标、R oss评分、性别、年龄、脉搏血氧饱和度(SpO2)及主心室类型等因素无关。结论TCPC后近2年神经内分泌系统仍处于应激状态,BNP增高可能与TCPC后特有的血流动力学状态有关;血浆BNP水平不能作为正确评估TCPC后心功能状态的指标。  相似文献   
104.
目的比较使用桡动脉和乳内动脉全动脉化冠状动脉旁路移植术(CABG)与使用一根乳内动脉和静脉做常规CABG的近期手术结果。方法从1999年1月到2005年1月,阜外心血管病医院共有123例患者(男114例、女9例,年龄52.2±10.1岁)采用全动脉化CABG(全动脉化组),血管移植材料为乳内动脉和桡动脉,目标血管桥在2根以上;同期行常规CABG115例(男102例、女13例,年龄60.3±9.1岁),血管的移植材料为一根乳内动脉和若干静脉桥(常规手术组)。比较两组患者术前、术中和术后的临床结果。结果术前资料比较,全动脉化组的患者年龄更小,常规手术组3支病变患者较多(54.5%vs.86.1%,P=0.001),全动脉化组有更多患者选择非体外循环CABG(26.0%vs.57.4%,P=0.001);在体外循环CABG中,全动脉化组需要更长的手术时间;平均移植血管根数全动脉化组少于常规手术组(2.6±0.7根vs.3.4±0.9根,P=0.001);住院死亡率全动脉化组为0.8%,常规手术组为0.9%,两组比较差异无统计学意义(P=1.000);术后近期并发症发生情况两组结果相似。结论对选择适合的患者采用全动脉化CABG能够提供较为安全的近期手术结果。  相似文献   
105.
Exercise intolerance is common in hemodialysis (HD) and renal transplant (RTx) patients. Aim of the study was to assess to what extent exercise capacity and skeletal muscle strength of RTx patients differ from HD patients and healthy controls and to elucidate potential determinants of exercise capacity in RTx patients. Exercise capacity, muscle strength, lean body mass (LBM) and physical activity level (PAL) were measured by cycle-ergometry, isokinetic dynamometry, DEXA and Baecke Questionnaire, respectively, in 35 RTx, 16 HD and 21 controls. VO2peak and muscle strength of the RTx patients were significantly lower compared to controls (p<0.01), but not different compared to HD patients. In RTx patients, strength (p<0.001), PAL (p=0.001) and age (p=0.045) were significant predictors of VO2peak. Muscle strength was related to LBM (p=0.001) and age (p=0.001), whereas gender (p<0.001) and renal function (p=0.01) turned out to be significant predictors of LBM. No effects of corticosteroids were observed. Exercise capacity and muscle strength seem equally reduced in RTx and HD patients compared to controls. In RTx patients, muscle strength and PAL are highly related to exercise capacity. Renal function appears to be a significant predictor of LBM, and through the LBM, of muscle strength and exercise capacity.  相似文献   
106.
目的 :了解测定血清钙、白蛋白的变化对孕妇影响的临床意义。方法 :采用邻甲酚酞络合酮、离子选择性电极法、溴甲酚绿法测定。结果 :孕妇组血清总钙、离子钙、白蛋白的含量明显低于非孕妇组 ,差异有非常显著性 (P<0 .0 1) ,中孕妇组与晚孕妇组比较血清总钙、离子钙没有差异 (P>0 .0 5 )。白蛋白含量晚孕妇组明显低于中孕妇组 ,差异有显著性 (P<0 .0 1)。结论 :血清总钙、离子钙、白蛋白对孕妇尤为重要。动态监测 ,及时补充可提高孕妇及胎儿的健康  相似文献   
107.
108.
The survival rate of avulsed permanent teeth following replantation is affected primarily by the duration of the extra-alveolar period and the nature of the storage conditions. These factors are believed to strongly affect the viability of periodontal ligament (PL) cells but in vitro assays of cell viability based on vital dye assays are only weakly correlated with the tooth survival rate after replantation. The aim of the present study was to examine the relative dependence of cell membrane integrity, attachment and clonogenic capacity of human PL cells on the temperature and duration of the extra-alveolar period and the type of storage medium. Twenty-four premolar teeth were extracted for orthodontic reasons from 9 patients 11–18 years of age. Teeth were maintained at 4°C or 23°C for 15, 30, 60 or 120 min in either milk or dry conditions. Cell membrane integrity was determined by BCECF/AM dye inclusion. Plating efficiency was determined by measurement of cell attachment at 3 and 6 h. The clonogenic capacity of progenitor cells was estimated by limiting dilution and colony counts. For all assays teeth stored in milk at 4°C showed the highest percentages of BCECF positive, attached cells with clonogenic capacity. Increased storage time (15–120 min) was associated with a 50% relative reduction of BCECF staining and a 5-fold relative reduction of cell attachment regardless of storage conditions. However, the clonogenic capacity of progenitor cells decreased 25-fold over the same duration of storage. These data demonstrate that in vitro assays of clonogenic capacity are much more sensitive to extra-oral storage time and storage conditions than dye inclusion or cell attachment. We suggest that in comparison with in vitro measures of cell membrane integrity, the clonogenic capacity of PL cells is more closely linked to tooth survival rate, probably reflecting the capacity of PL progenitor cells to recolonize the root surface after replantation.  相似文献   
109.
作为全髋置换术(THR)的一种替代技术,全髋表面置换术(THSR)通过保留股骨头、颈骨块而恢复髋关节正常的生物力学特性及关节的稳定性,并由于未破坏股骨髓腔结构而具有易翻修的潜力。在其发展长达半个多世纪的三个技术时期中,通过不断积累经验,使得假体系统在材料、设计及固定方法等技术参数方面获得长足改进。但仍存在尚待解决的问题。新一代金-金全髋表面假体系统的问世是髋关节置换术的一个重要历程碑,在不到10年的临床随访中其早期疗效非常满意,但中、长期疗效尚不确定,需待与其它方法作进一步长期的、随机化对照性研究。  相似文献   
110.
目的:总结喉癌全喉切除术后Ⅰ期安放发音管发音重建的临床经验。方法:分析自1998年9月至2002年5月全喉切除术后Ⅰ期Blom-Singer发音重建56例的发音情况。结果:Ⅰ期安放发音管发音重建成功率92.9%,发音流利、响亮、清晰。结论:全喉切除术后Ⅰ期安放发音管发音重建成功率高。  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