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   1371篇
  免费   227篇
  国内免费   37篇
耳鼻咽喉   13篇
儿科学   5篇
妇产科学   3篇
基础医学   188篇
口腔科学   282篇
临床医学   129篇
内科学   128篇
皮肤病学   21篇
神经病学   37篇
特种医学   38篇
外科学   164篇
综合类   210篇
预防医学   97篇
眼科学   34篇
药学   122篇
  5篇
中国医学   89篇
肿瘤学   70篇
  2024年   1篇
  2023年   20篇
  2022年   45篇
  2021年   66篇
  2020年   79篇
  2019年   91篇
  2018年   82篇
  2017年   100篇
  2016年   105篇
  2015年   88篇
  2014年   122篇
  2013年   128篇
  2012年   100篇
  2011年   84篇
  2010年   88篇
  2009年   65篇
  2008年   49篇
  2007年   55篇
  2006年   45篇
  2005年   28篇
  2004年   30篇
  2003年   39篇
  2002年   34篇
  2001年   22篇
  2000年   13篇
  1999年   11篇
  1998年   5篇
  1997年   3篇
  1996年   4篇
  1995年   5篇
  1994年   4篇
  1993年   1篇
  1992年   3篇
  1991年   4篇
  1989年   3篇
  1988年   3篇
  1986年   1篇
  1985年   1篇
  1983年   1篇
  1982年   4篇
  1980年   2篇
  1977年   1篇
排序方式: 共有1635条查询结果,搜索用时 0 毫秒
1.
微小切口胆囊切除术2260例效果观察   总被引:1,自引:0,他引:1  
目的 总结微小切口胆囊切除术治疗胆道系统疾病的经验。方法 对2002-2004年连续收治的2260例胆囊、胆道系统疾病实施微小切口手术的临床观察资料进行回顾性分析。结果 本组2260例微小切口胆囊切除术的患者无一例因手术原因死亡;术后无残留小胆囊;无胆汁漏及腹腔脓肿,亦无伤口全层裂开及切口疝形成。结论 该术式损伤小、局部显露清楚、不易发生副损伤,可同时行胆总管探查术,特殊情况下可随时改变手术方式。  相似文献   
2.
Design and real‐time validation of a robust fixed‐order H2 optimal controller for micro aerial vehicle, named Sarika‐2, is presented. Strengthened discrete optimal projection equations, which approximate the first‐order necessary optimality condition, are used for the controller design. Effect of low‐frequency gust disturbance and high‐frequency sensor noise is alleviated through the output sensitivity and control sensitivity minimization. The novelty of this paper is that a single robust H2 controller, which is designed at the central operating point, ensures simultaneous stabilization of the radio‐controlled aircraft over the entire cruise speed range of 16–26 m/s. The controller is implemented on a digital‐signal‐processor‐based flight computer, and subsequently, it is validated through the real‐time hardware‐in‐loop‐simulation. The responses obtained from the hardware‐in‐loop‐simulation compares well with those obtained from the off‐line simulation. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   
3.
目的分析应用Orthofix-微型器治疗第一掌骨基底部Bennett骨折的临床疗效。方法收集2009年1月~2013年1月我院31例采用Orthofix-微型器治疗的第一掌骨基底部Bennett骨折患者。记录患者年龄、性别等基线资料,以及术后上肢臂、肩、手功能调查量表(Disabilities of the arm,shoulder and hand,DASH)评分,随访终末期采用指总关节活动度(Total action movement,TAM)评分。结果随访6~24个月,平均14.4月,手术时间为18~40分钟,平均29.1分钟,术中出血量10~30m L,平均14.5m L。术后3月、术后6月及终末期DASH评分之间比较,差异均有统计学意义(0.05)。随访终末期,其中26例解剖复位,5例骨折对线良好,TAM评分优22例,良7例,差2例。随访期间未发生桡神经浅支损伤、钉道感染等并发症。结论 Orthofix-微型外固定器治疗Bennett骨折操作简单、疗效满意。  相似文献   
4.
Summary A technique for culturing small quantities of mammalian cells on modified microscope slides is described. The modified microscope slides were Bellco Glass, Inc., toxoplasmosis slides and the cell cultures used were early passage bovine embryonic lung cells and continuous cell lines of porcine and canine origins. The slide cell cultures were either uninfected or infected with selected viruses or the obligate intracellular protozoanEncephalitozoon caniculi for utilization in direct and indirect fluorescent antibody testing or in peroxidase antiperoxidase immunosorbant assays.  相似文献   
5.
Morphometric analysis of anatomical landmarks allows researchers to identify specific morphological differences between natural populations or experimental groups, but manually identifying landmarks is time‐consuming. We compare manually and automatically generated adult mouse skull landmarks and subsequent morphometric analyses to elucidate how switching from manual to automated landmarking will impact morphometric analysis results for large mouse (Mus musculus) samples (n = 1205) that represent a wide range of ‘normal’ phenotypic variation (62 genotypes). Other studies have suggested that the use of automated landmarking methods is feasible, but this study is the first to compare the utility of current automated approaches to manual landmarking for a large dataset that allows the quantification of intra‐ and inter‐strain variation. With this unique sample, we investigated how switching to a non‐linear image registration‐based automated landmarking method impacts estimated differences in genotype mean shape and shape variance‐covariance structure. In addition, we tested whether an initial registration of specimen images to genotype‐specific averages improves automatic landmark identification accuracy. Our results indicated that automated landmark placement was significantly different than manual landmark placement but that estimated skull shape covariation was correlated across methods. The addition of a preliminary genotype‐specific registration step as part of a two‐level procedure did not substantially improve on the accuracy of one‐level automatic landmark placement. The landmarks with the lowest automatic landmark accuracy are found in locations with poor image registration alignment. The most serious outliers within morphometric analysis of automated landmarks displayed instances of stochastic image registration error that are likely representative of errors common when applying image registration methods to micro‐computed tomography datasets that were initially collected with manual landmarking in mind. Additional efforts during specimen preparation and image acquisition can help reduce the number of registration errors and improve registration results. A reduction in skull shape variance estimates were noted for automated landmarking methods compared with manual landmarking. This partially reflects an underestimation of more extreme genotype shapes and loss of biological signal, but largely represents the fact that automated methods do not suffer from intra‐observer landmarking error. For appropriate samples and research questions, our image registration‐based automated landmarking method can eliminate the time required for manual landmarking and have a similar power to identify shape differences between inbred mouse genotypes.  相似文献   
6.
目的探讨微观社会资本对农转非居民自评健康与客观健康认知一致性的影响。方法两层logistic回归模型分析微观社会资本和人口学因素对健康认知一致性的影响。结果自评健康和客观健康的一致率为63.89%,个体社会资本和年龄对主客观健康一致性产生影响。结论使用自评健康作为健康指标时,应考虑个体社会资本的影响,提高自评健康的预测准确性。  相似文献   
7.
目的 :研究非小细胞肺癌 (NSCL C)的预后与血管内皮生长因子 (VEGF)表达及肿瘤微血管定量间的关系。方法 :对81例行手术治疗的 NSCL C患者运用免疫组织化学的方法检测 VEGF的表达及微血管定量 ,检测 VEGF使用抗 VEGF单克隆抗体 ;检测微血管定量用抗 CD34 单克隆抗体。结果 :在术后半年出现转移的 32例 NSCL C中微血管定量为 (32± 15 .4)根/ mm3比术后未出现转移的 49例患者 (12± 8.6 )根 / mm3明显增高 ,经统计学处理 (P=0 .0 0 1)。在术后半年出现转移的 32例中有 2 4例 VEGF表达阳性 (75 % ) ,在术后未出现转移的 49例中有 2 5例 VEGF表达阳性 (5 1% ) ,经统计学处理 (P=0 .0 31)。结论 :NSCL C的转移形式为血管形成依赖性 ,VEGF是 NSCL C的血管形成的一个重要因素。VEGF的表达是检测NSCL C预后的一个有意义的指标  相似文献   
8.
A novel method of preparing small-sized microcapsules using a Turbotak air-atomizer is reported. Alginate-polylysine microcapsules containing Bacillus Calmette Guérin vaccine have been prepared by an adaptation of the method of Lim (1) which allows the manufacture of small-sized microcapsules. A Turbotak is used to spray sodium alginate solution into calcium chloride solution to form temporary calcium alginate microgel capsules. These temporary microgel droplets are subsequently cross-linked with polylysine to form permanent membranes. Microcapules in the size range of 5–15 µm have been produced which can be compared to an average diameter of 300 µm obtained by the method reported by Lim. The microcapsule size is dependent on the conditions of operation of the Turbotak and the concentration of the sodium alginate solution. Particles within the size range 5–15 µm can be reproducibly manufactured using the conditions of operation reported here. Other size ranges below the minimum of 300 µm reported by Lim are also feasible using this technique.  相似文献   
9.
新型药物开发制备过程中,需要对药物颗粒进行粒子设计,通过多层微胶囊化而得到复合包覆药物颗粒。药物包覆、微胶囊制备方法很多,可分为化学法、物理化学法、物理法。本文着重介绍了制备复合多层包覆药物颗粒的几种物理机械方法:复合杂化系统,高速椭圆转子混合法、喷流床包覆法。简要分析了该技术用于中药现代化加工的可能性。  相似文献   
10.
目的 探讨自体微小颗粒骨复合碱性成纤维细胞生长因子(basic fibroblast growth factor,bFGF)治疗骨缺损的效果,为其临床应用提供实验依据。方法 将36只新西兰白兔双侧桡骨中上段制成骨缺损模型,分别植入自体微小颗粒骨、bFGF和自体微小颗粒骨与bFGF的复合物,同时设空白对照组,分别手术后第2、4、8周进行大体观察,X检查及组织学检查。术后第8周进行骨密度测定,比较修复骨缺损的疗效。结果 经大体观察、组织学及X线检查发现,术后第8周自体微小颗粒骨复合bFGF能更有效地修复节段性骨缺损,对照组无骨愈合迹象。术后第8周骨密度测定证明自体微小颗粒骨复合bFGF组骨密度值明显高于对照组。结论 自体微小颗粒骨复合bFGF组成骨速度快,成骨量多,修复骨缺损的能力明显强于自体微小颗粒骨组及单纯bFGF组。  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