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   388篇
  免费   42篇
  国内免费   15篇
电工技术   17篇
综合类   11篇
化学工业   43篇
金属工艺   12篇
机械仪表   22篇
建筑科学   69篇
矿业工程   1篇
能源动力   54篇
轻工业   8篇
水利工程   22篇
石油天然气   17篇
武器工业   9篇
无线电   26篇
一般工业技术   89篇
冶金工业   2篇
原子能技术   2篇
自动化技术   41篇
  2024年   2篇
  2023年   20篇
  2022年   16篇
  2021年   28篇
  2020年   22篇
  2019年   13篇
  2018年   3篇
  2017年   6篇
  2016年   7篇
  2015年   6篇
  2014年   27篇
  2013年   34篇
  2012年   47篇
  2011年   39篇
  2010年   34篇
  2009年   36篇
  2008年   10篇
  2007年   33篇
  2006年   27篇
  2005年   12篇
  2004年   6篇
  2003年   3篇
  2002年   5篇
  2001年   3篇
  2000年   2篇
  1998年   2篇
  1997年   1篇
  1976年   1篇
排序方式: 共有445条查询结果,搜索用时 15 毫秒
1.
Tumor-specific enhanced delivery of chemotherapeutics and modulators to tumor cells and activated pancreatic stellate cells (aPSCs), respectively, represents safer and more effective therapy for pancreatic cancer. Herein, a membrane type 1-matrix metalloproteinase (MT1-MMP)-cleavable spacer is used to assemble low-density cRGDfK onto thermosensitive liposomes loaded with phosphorylated calcipotriol (PCAL) and doxorubicin (DOX), yielding MR-T-PD. The liposome-linked cRGDfK prodrug on MR-T-PD surface is first activated by MT1-MMP, which is selectively expressed on tumor endothelial cells, to release cRGDfK. The free cRGDfK specifically promotes tumor angiogenesis, leading to 3.4-fold higher accumulation and a wider distribution of MR-T-PD in tumors. Furthermore, MR-T-PD rapidly releases PCAL and DOX into the interstitium under heat treatment. The released DOX enters tumor cells to induce apoptosis, whereas the PCAL prodrug is converted to CAL by alkaline phosphatase on the surface of aPSCs; CAL can then enter aPSCs to induce quiescence and promote the antitumor effect of DOX. Finally, by enhancing the exposure of DOX and CAL to tumor cells and aPSCs, respectively, in a tumor-specific manner, MR-T-PD exerts superior efficacy (a 5.9-fold decrease in tumor weight) without causing additional side effects. Overall, this prodrug-based smart liposome system represents a promising paradigm for pancreatic cancer therapy.  相似文献   
2.
3.
4.
The purpose of this study is to provide a comprehensive outline of the Value Chain (VC)1 of bio-coal in Finland, define the proper business models of bio-coal business, and investigate the interrelationships between VC activities. The major findings are: 1) the study found significant interrelationships between support and primary activities in the bio-coal VC which suggest that we should not emphasis only the core value/primary activities of the bio-coal business, but pay more attentions to the “side values”/support activities; 2) The study identified political and environmental factors as the effective drivers, while technology and cost-profit uncertainty as major restrictions for the Finnish bio-coal business. The authors would like to suggest that instead of purely “environmental concerns”, the term “sustainability credentials” should be emphasized, which means value creating and adding items should not limit to monetary values, but consider social and environmental value propositions. 3) The study identified “low competition” in the current bio-coal business in Finland, which implies opportunities of market entrance for Finnish and international companies; 4) The study identified that the current Finnish bio-coal model is the decentralized model at the local level. However, the future Finnish bio-coal model will be a large scaled model, with a focus on export sales.  相似文献   
5.
6.
王有晴  陶俊 《给水排水》2022,48(1):104-110
通过调研和分析上海市28个处于设计、在建和建成不同阶段的大型公共建筑项目的节水技术、节水管理措施,发现受调研项目基本能够满足现行国家、地方规范标准的相关规定,但也存在部分项目非传统水资源利用系统设计不合理,仅为满足绿色建筑星级评定的现象。相关部门近年更新了绿色建筑评价标准条文以避免这种形式上的浪费,在此基础上,建议颁布更明确和更全面的公共建筑节水评价标准用以规范建筑节水技术应用,并且应加强宣传建筑节水所产生的社会及环境效益。  相似文献   
7.
Two-step sintering (TSS) was applied to control the grain growth during sintering of a novel calcium magnesium silicate (Ca3MgSi2O8 – Merwinite) bioceramic. Sol–gel derived nanopowders with the mean particle size of about 90 nm were sintered under different TSS regimes to investigate the effect of sintering parameters on densification behavior and grain growth suppression. Results showed that sintering of merwinite nanopowder under optimum TSS condition (T1 = 1300 °C, T2 = 1250 °C) yielded fully dense bodies with finest microstructure. Merwinite compacts held at T2 = 1250 °C for 20 h had the average grain size of 633 nm while the relative density of about 98% was achieved. Mechanical testing was performed to investigate the effect of grain growth suppression on the hardness and fracture toughness. Comparison of mechanical data for samples sintered under two sintering regimes, including TSS and normal sintering (NS), showed TSS process resulted in significant enhancement of fracture toughness from 1.77 to 2.68 MPa m1/2.  相似文献   
8.
在单轴压缩试验机的基础上研制了一套超声波三轴压缩试验系统,实现了三轴压缩过程中超声波的全程测试。对一组混凝土试样进行了试验研究,采用小波分析对超声波数据进行处理。在频域范围内提出了三个能反映试样中损伤演化的特征量:归一化第一能量峰值、归一化第二能量峰值、第一能量峰值对应的尺度。本文为研究损伤本构关系提供了新的设备,提出的三个特征量能够反映材料内部结构的变化,特别是第三个特征量具有较强的规律性,可以作为描述材料结构变化的损伤变量。  相似文献   
9.
屋盖结构柱顶隔震技术的研究   总被引:5,自引:0,他引:5  
根据屋盖结构的特点,提出柱顶隔震技术;随之,建立串联弹簧模型理论用于初步确定隔震垫参数,再使用非线性动力时程分析法进行详细设计。算例表明,屋盖隔震技术不仅大大降低了屋盖本身的反应,也有效保护了柱和基础等下部结构,而且屋盖侧移和隔震垫变形正常,因此柱顶隔震技术应用于屋盖结构是可行的。  相似文献   
10.
本文详细介绍了外滩中信城主楼的结构设计.针对结构超限,在结构布置、计算分析上作出了处理,使整体设计满足规范要求,为类似工程提供参考.  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