全文获取类型
收费全文 | 448篇 |
免费 | 95篇 |
国内免费 | 38篇 |
专业分类
电工技术 | 56篇 |
综合类 | 62篇 |
化学工业 | 39篇 |
金属工艺 | 19篇 |
机械仪表 | 16篇 |
建筑科学 | 28篇 |
矿业工程 | 7篇 |
能源动力 | 16篇 |
轻工业 | 16篇 |
水利工程 | 26篇 |
石油天然气 | 15篇 |
无线电 | 147篇 |
一般工业技术 | 28篇 |
冶金工业 | 11篇 |
原子能技术 | 6篇 |
自动化技术 | 89篇 |
出版年
2024年 | 1篇 |
2023年 | 3篇 |
2022年 | 6篇 |
2021年 | 9篇 |
2020年 | 20篇 |
2019年 | 17篇 |
2018年 | 14篇 |
2017年 | 22篇 |
2016年 | 38篇 |
2015年 | 32篇 |
2014年 | 46篇 |
2013年 | 30篇 |
2012年 | 23篇 |
2011年 | 38篇 |
2010年 | 19篇 |
2009年 | 25篇 |
2008年 | 24篇 |
2007年 | 18篇 |
2006年 | 25篇 |
2005年 | 19篇 |
2004年 | 20篇 |
2003年 | 27篇 |
2002年 | 19篇 |
2001年 | 24篇 |
2000年 | 26篇 |
1999年 | 9篇 |
1998年 | 7篇 |
1997年 | 4篇 |
1996年 | 2篇 |
1995年 | 4篇 |
1994年 | 3篇 |
1993年 | 4篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1986年 | 1篇 |
排序方式: 共有581条查询结果,搜索用时 250 毫秒
11.
12.
Construction of Asymmetrical Hexameric Biomimetic Motors with Continuous Single‐Directional Motion by Sequential Coordination
下载免费PDF全文
![点击此处可从《Small (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Zhengyi Zhao Hui Zhang Dan Shu Carlo Montemagno Baoquan Ding Jingyuan Li Peixuan Guo 《Small (Weinheim an der Bergstrasse, Germany)》2017,13(1)
The significance of bionanomotors in nanotechnology is analogous to mechanical motors in daily life. Here the principle and approach for designing and constructing biomimetic nanomotors with continuous single‐directional motion are reported. This bionanomotor is composed of a dodecameric protein channel, a six‐pRNA ring, and an ATPase hexamer. Based on recent elucidations of the one‐way revolving mechanisms of the phi29 double‐stranded DNA (dsDNA) motor, various RNA and protein elements are designed and tested by single‐molecule imaging and biochemical assays, with which the motor with active components has been constructed. The motor motion direction is controlled by three operation elements: (1) Asymmetrical ATPase with ATP‐interacting domains for alternative DNA binding/pushing regulated by an arginine finger in a sequential action manner. The arginine finger bridges two adjacent ATPase subunits into a non‐covalent dimer, resulting in an asymmetrical hexameric complex containing one dimer and four monomers. (2) The dsDNA translocation channel as a one‐way valve. (3) The hexameric pRNA ring geared with left‐/right‐handed loops. Assessments of these constructs reveal that one inactive subunit of pRNA/ATPase is sufficient to completely block motor function (defined as K = 1), implying that these components work sequentially based on the principle of binomial distribution and Yang Hui's triangle. 相似文献
13.
14.
随着各类智能终端的普及,多屏互动等跨设备使用硬件资源的应用不断涌现,对硬件资源管理的跨平台性和交互扩展性提出了更高的要求.然而,当前针对硬件资源共享的应用大多是缺少交互性的跨设备投影镜像技术,或者只是相互独立的简单应用,面向的平台、硬件资源类型单一,难以灵活有效地应对新增需求.针对这一问题,研究了个人自组织网络环境下多设备的硬件资源(键盘、鼠标、摄像头等)的管理调配,并提出一个具有良好跨平台性、可扩展性的应用框架,使得设备能够像使用本机硬件一样使用其他设备上的硬件资源,借此方便用户对其多个设备进行管理控制.该框架包括设备间通信和硬件资源管理两层,前者提供信息传输服务,保证实时通信,后者负责管理可以访问到所有硬件资源,并提供资源申请、使用和状态改变通知等功能,极大地方便了跨设备应用的开发. 相似文献
15.
李鉴 《计算机与数字工程》2000,28(2):9-12
本文通过分析舰载作战指挥系统对网络的需求,提出了一套双冗余网络方案,在Sun/Solaris,PC/加固微机/Vxworks等平台上设计并开发了双冗余网络实用软件包Bnet,该软件解决了通信中的可靠性,异种计算机、异种操作系统的互通互联、双冗余网络的工作方式、测试方法和切换过程等问题。 相似文献
16.
Roongnapa Suedee Wimon Intakong Peter A. Lieberzeit Pikul Wanichapichart Pipat Chooto Franz L. Dickert 《应用聚合物科学杂志》2007,106(6):3861-3871
A molecularly trichloroacetic acid (TCAA) imprinted non‐crosslinked polypyrole (TCAA‐MIPpy) has been successfully prepared and evaluated in its properties for both piezoelectric quartz crystal microbalance (QCM) and electrochemical means of detection, and application of such sensors for determination of haloacetic acid concentrations in water. Haloacetic acid selectivity was demonstrated in gravimetric or in electrochemical sensors via either cyclic voltammetric or inter‐digitated conductometric (IDC) analyses studies upon comparison with nonimprinted polypyrrole and TCAA‐imprinted polypyrrole. The measurement results with all these systems revealed that the prepared molecularly imprinted polymer can recognize TCAA well from structurally similar compounds. The TCAA‐MIPpy incorporated with only the IDC transduction system produced the specific signal for TCAA detection in aqueous environment, which is useful for the quantifying TCAA disinfection by‐product in water. The analytical application for determination of TCAA in real‐life samples was readily achieved with the incorporation of TCAA‐MIPpy in the IDC analysis system, the results revealing the high sensitivity and selectivity of the method. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 相似文献
17.
基于超球近似子空间的协同优化方法及应用研究 总被引:7,自引:0,他引:7
针对协同优化的计算结构及计算困难,提出了学科间不一致信息概念,并据此形成系统级优化的超球设计空间。有效地解决了原始系统级优化问题不满足Kuhn-Tucker条件造成的计算困难.并克服了已有梯度方法计算易发散、响应面方法计算量大的缺点。利用中提出的方法对一齿轮减速箱进行了设计,实现了并行设计的目的,设计结果表明了本方法的有效性。 相似文献
18.
大型汽轮发电机转子绕组匝间短路故障的测试与分析 总被引:4,自引:0,他引:4
本文利用气隙探测线圈和RSO两种测量方法,分析大亚湾核电站2#发电机组转子绕组匝间短路的发生、发展以及最后的接地过程,并对匝间短路的检查分析方法进行了初步探讨。 相似文献
19.
汽轮发电机转子绕组匝间短路故障诊断新判据 总被引:28,自引:3,他引:28
该文分析了发生转子绕组匝间短路时,汽轮发电机的电磁特性及导致的相关电气参量的变化,提出了在转子发生匝间短路故障时,励磁电流增加而无功输出量却相对减少的特征。根据确定的故障特征,找到一种利用故障前后励磁电流相对变化率作为识别故障的方法,从而建立了在线识别转子匝间短路故障的判据。该判据可以反映故障的严重程度,最后利用动态模拟试验机组进行了相关的实验,得到了与理论分析相吻合的结论。 相似文献
20.
Christian Berggren 《International Journal of Project Management》2019,37(3):461-472
In innovation and project management studies incremental development projects are perceived as theoreticlly and organisationally uninteresting. By means of a longitudinal study of product improvement projects at an automobile firm, this paper challenges such views and shows how the cumulative impact of the studied sequence resulted in a competitive repositioning of the company's product portfolio during a financially difficult period. Project managers achieved this by transcending the separation between exploration and exploitation projects; they not only adhered to time, cost and quality goals but also tried out new ways of testing and experimenting with controversial technical ideas. The paper analyzes the intensive inter project learning that generated these ambidextrous capabilities and emphasizes that practices at the project-level need to be buttressed by expanded management learning and capability development also at the sequence level. 相似文献