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   35745篇
  免费   3431篇
  国内免费   2683篇
耳鼻咽喉   237篇
儿科学   467篇
妇产科学   264篇
基础医学   3731篇
口腔科学   559篇
临床医学   5036篇
内科学   4762篇
皮肤病学   331篇
神经病学   1534篇
特种医学   978篇
外国民族医学   17篇
外科学   2892篇
综合类   7796篇
现状与发展   13篇
预防医学   2893篇
眼科学   940篇
药学   4161篇
  40篇
中国医学   2676篇
肿瘤学   2532篇
  2024年   139篇
  2023年   594篇
  2022年   1479篇
  2021年   1842篇
  2020年   1460篇
  2019年   1094篇
  2018年   1132篇
  2017年   1170篇
  2016年   1012篇
  2015年   1654篇
  2014年   2139篇
  2013年   1978篇
  2012年   3043篇
  2011年   3199篇
  2010年   2236篇
  2009年   1878篇
  2008年   2201篇
  2007年   2206篇
  2006年   2001篇
  2005年   1734篇
  2004年   1225篇
  2003年   1115篇
  2002年   911篇
  2001年   798篇
  2000年   678篇
  1999年   631篇
  1998年   353篇
  1997年   361篇
  1996年   276篇
  1995年   236篇
  1994年   230篇
  1993年   134篇
  1992年   126篇
  1991年   146篇
  1990年   113篇
  1989年   92篇
  1988年   67篇
  1987年   57篇
  1986年   44篇
  1985年   25篇
  1984年   13篇
  1983年   13篇
  1982年   7篇
  1981年   10篇
  1980年   3篇
  1979年   4篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
The effects of vagal and sympathetic nerves on the transmembranepotentials of cardiac cells of toad were observed by means of microelectrodetechnique.The vagal nerve was stimulated there would be an increase in restingpotential and acceleration in repolarization of action potential(AP).However,ifatropine was used before stimulation the above-mentioned phenomena woulddisappear.When the sympathetic nerve was stimulated the AP amplitudeincreased,but resting potential(RP)remained the same.The increase of APresulted from the increases of overshoot.When the sympathetic nerve wasstimulated although the heart rate increased and the duration of AP wasshortened,the plateau phase of AP was prolonged.These results suggest that theeffects of vagal and sympathetic nerves on the transmembrane potential of cardiacventricular cells are coordinated and the normal characteritics of transmembranepotential are maintained by both the vagal and sympathetic nerves.  相似文献   
82.
Objective To evaluate the character of the collagen-chitosan-chondroitin sulfate scaffold seeded with rat adipose tissue-derived stromal cells. Methods A dipose tissue were harvested from 6 weeks old Wistar rats and the stromal cells were harvested by type Ⅰ collagenase and then cultured in vitro. Type Ⅰ collagen was fully mixed with chitosan, freeze-dried and cross-linked with chondroitin sulfate, then freeze-dried again and sterilized by ethylene oxide. The pore diameter, water content, porosity of the scaffold were tested. The adipose tissue-derived stromal cells were digested, seeded into the plates, scaffold, and cen-trifuged into pellet, and then induced into cartilage. MTT detection for cell proliferation was done. After 3 weeks, the cell morphology, and cell proliferation and adhesion were observed, and chondrngenic differenti-ation was also analyzed. Results The pore diameter, water content, porosity tested for the scaffold showed an appropriate form. Cell proliferation showed faster in the scaffold and pellet culture system after 5 day, there was still cell proliferation in the scaffold system after 14 days but no obvious changes in the pellet cul-ture system; ceils on the scaffold proliferated densely showed by histological staining, but there was a scaf-fold structure residues in the inner layer. The finding of type Ⅱ immunohistochemistry stain showed that cells express strong positive for type Ⅱ collagen in the scaffold and pellet culture system whereas it was weakly positive in the plate culture system; the specific mRNA for cartilage, type Ⅱ collagen, aggrecan and SOX-9 were expressed in all three systems showed by RT-PCR, but type X collagen was expressed continu-ously in the plate culture system and expressed after 21 days in the pellet culture system, whereas it was not detected in the collagen-chitosan-chondroitin sulfate scaffold system. Conclusion The parameters of the collagen-chitosan-chondroitin sulfate scaffold were suitable in our study. The results suggested that it can promote the adipose tissue-derived stromal cells proliferation and chondrogenic differentiation better than the plate and pellet culture systems and maintain the phenotype of chondrocytes well; it is the optimal choice for cartilage tissue engineering in the future.  相似文献   
83.
通过平板初筛和摇瓶复筛,从371株菌中筛得一株有工业生产价值的胆固醇酯酶产生菌,并对它进行了发酵条件的研究。用所获得的胆固醇酯酶配制的三酶试剂具有良好的稳定性,适用于临床检测。  相似文献   
84.
用复方泛影葡胺注射液对1,020例不孕症者作子宫输卵管造影。结果:子宫腔形态异常540例。双侧输卵管通畅但形态异常者268例。单侧输卵管通畅但形态异常者110例。结果表明:子宫输卵管形态异常与不孕有密切关系。  相似文献   
85.
元素释放器元素释放动态观察   总被引:1,自引:0,他引:1  
应用我们实验室自制的元素释放器于1994-1996年进行了碘元素释放动态研究,取6个带有不同释放板的释放器和3个目前应用的缓释器为对照,每个均装入2克碘酸钾,置于水盐水中,应用溴氧化法每两周测定一次水碘含量。  相似文献   
86.
A pilot study was conducted of the biological characteristics of the leukemia cells of newly diagnosed patients with poor prognosis acute myelogenous leukemia (AML). This study included measurements of the pretherapy proliferative rate of the leukemia cells in vivo, assessment of differentiation in vivo during remission induction therapy, and the level of expression of the fms, myc, and IL1β genes in pretherapy leukemia cells. Short cell cycle times were characteristic of the best prognostic category and were associated with a rapid reduction in marrow leukemia cells in cytosine arabinoside (araC)-sensitive patients. Expression of c-fms was associated with rapid reduction in marrow leukemia cells during araC therapy and with a successful treatment outcome. Expression of the IL1β gene was associated with short remissions. These studies suggest that when compared to newly diagnosed standard prognosis AML, the leukemia of poor prognosis patients is more likely to exhibit long cell cycle times, low levels of fms expression, and is less likely to be associated with myeloid differentiation during remission induction therapy. © 1993 Wiley-Liss, Inc.  相似文献   
87.
组织工程化肌腱研究进展   总被引:17,自引:2,他引:15  
对组织工程化肌腱领域中目前研究的主要成果进行综述,着重阐述了肌腱细胞外基质替代物、肌腱细胞生物学性质及肌腱细胞与细胞外基质材料复合研究中的主要问题。认为,研制适于肌腱细胞生长、粘附和发挥功能的细胞外基质材料;建立生长、增殖可调控的肌腱细胞系;在模拟体内力学条件下,进行肌腱细胞三维培养,将是研究具有特定修复功能的组织工程化肌腱的重要问题。  相似文献   
88.
为研究心肌血管重建的机理,在15只鼠心、12只免心,用308nm的XeCl准分子激光在活体上照射左心室壁,形成边缘清楚而光滑的圆筒状心肌管道。在活体心室壁的激光管道周围,心肌细胞的损伤很轻微,无炭化焦痂层,未见碎片和凝固坏死层,只有薄层嗜伊红性变和肌浆凝聚两个断续的条形变化带。当心室壁由激光穿透时,血液从心腔进入激光管道,并与周围扩张的血管相通。实验结果提示,由于准分子激光不造成明显的热损伤,因而可能适合于心肌血管的重建。  相似文献   
89.
对金乌香冲剂中槟榔碱进行了酸性染料比色法定量方法研究,结果表明在pH=5.0时,槟榔碱可与溴甲酚绿生成稳定呈色离子对,在槟榔碱浓度范围1.65μg/mL~10.4μg/mL内线性关系良好,r=0.9992,平均回收率99.7%,RSD=2.1%(n=5)。  相似文献   
90.
目的:观察病房康复延伸护理对脑卒中迟缓性偏瘫患者三维步态时空参数的影响。方法:将60例脑卒中迟缓性偏瘫患者随机分为常规护理组(A组,n=30)、病房康复延伸护理组(B组,n=30)两组,予以相应的方法治疗8周,评估治疗前后两组患者三维步态时空参数。结果:与治疗前相比,治疗后两组患者的步长、步幅、步速、步频、支撑相、双支撑相等参数及B组摆动相均有不同程度的改善(P<0.05); A组摆动相和步宽及B组步宽的变化差异无统计学意义(P>0.05)。与治疗后A组比较,治疗后B组的步长、步幅、步速、步频、支撑相、双支撑相等参数改善较为明显(P<0.05),步宽和摆动相的改善差异无统计学意义(P>0.05)。结论:病房康复延伸护理能改善脑卒中迟缓性偏瘫患者三维步态时空参数,具有临床意义。  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