全文获取类型
收费全文 | 3198篇 |
免费 | 292篇 |
国内免费 | 177篇 |
专业分类
电工技术 | 33篇 |
综合类 | 238篇 |
化学工业 | 453篇 |
金属工艺 | 33篇 |
机械仪表 | 78篇 |
建筑科学 | 145篇 |
矿业工程 | 114篇 |
能源动力 | 74篇 |
轻工业 | 11篇 |
水利工程 | 16篇 |
石油天然气 | 341篇 |
武器工业 | 2篇 |
无线电 | 705篇 |
一般工业技术 | 247篇 |
冶金工业 | 15篇 |
原子能技术 | 10篇 |
自动化技术 | 1152篇 |
出版年
2024年 | 12篇 |
2023年 | 26篇 |
2022年 | 50篇 |
2021年 | 81篇 |
2020年 | 77篇 |
2019年 | 57篇 |
2018年 | 71篇 |
2017年 | 92篇 |
2016年 | 109篇 |
2015年 | 93篇 |
2014年 | 177篇 |
2013年 | 232篇 |
2012年 | 199篇 |
2011年 | 228篇 |
2010年 | 214篇 |
2009年 | 210篇 |
2008年 | 196篇 |
2007年 | 255篇 |
2006年 | 234篇 |
2005年 | 203篇 |
2004年 | 148篇 |
2003年 | 122篇 |
2002年 | 109篇 |
2001年 | 66篇 |
2000年 | 63篇 |
1999年 | 49篇 |
1998年 | 47篇 |
1997年 | 41篇 |
1996年 | 46篇 |
1995年 | 33篇 |
1994年 | 24篇 |
1993年 | 18篇 |
1992年 | 20篇 |
1991年 | 10篇 |
1990年 | 12篇 |
1989年 | 8篇 |
1988年 | 9篇 |
1987年 | 1篇 |
1986年 | 3篇 |
1984年 | 1篇 |
1983年 | 5篇 |
1982年 | 7篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1976年 | 1篇 |
1975年 | 3篇 |
1974年 | 1篇 |
1970年 | 1篇 |
1954年 | 1篇 |
排序方式: 共有3667条查询结果,搜索用时 15 毫秒
71.
以大型销售MIS的数据安全问题为例,提出以终端ID号、钥匙盘ID号和终端用户样本指纹绑定为一体的身份认证方案。该方案采用软硬件协同工作方式,克服了传统身份认证模式或安全性能低,或运算成本高等缺陷,提高了认证效率,并保证了合法用户操作的唯一性和认证过程的不可抵赖性。提出的基于ECC与一维混沌加密算法优点相结合的混合加密方案,使基于互联网传送的数据安全性有了实质性提高。基于分治叠加法的大整数计算成果运用,克服了计算机精度域的限制,使密钥空间从理论上趋向于无穷大。试验结果表明,基于混合加密算法的数据安全方案具有良好的抗穷举攻击和抗差分攻击能力。该项研究为解决各类MIS的数据安全问题提供了重要策略,意义重大。 相似文献
72.
Tharindu Patikirikorala Liuping WangAlan Colman Jun Han 《Control Engineering Practice》2012,20(1):49-61
Runtime management of Quality of Service (QoS) performance and resource provisioning is a vital issue in shared resource software environments. A useful performance management technique for such software systems is the relative guarantee feedback control scheme. The existing approaches for this class of control systems are mainly based on off-line linear or on-line model identification and control techniques, which tend to have performance issues in the presence of nonlinearities induced by this scheme. Instead of using such modeling techniques, this paper proposes a new approach for QoS performance management and resource provisioning by using an off-line identification of Hammerstein and Wiener nonlinear block structural model. Using the characteristic structure of the nonlinear model, a predictive feedback controller based on a gain schedule technique is incorporated in the design to achieve the performance objectives. The proposed approach is validated using experiments based on a prototype, demonstrating superior runtime QoS performance management and resource provisioning in a complex software system. 相似文献
73.
介绍了无线防失提醒机的电路工作原理、装配与调试。该无线防失提醒机采用无线遥控,可以任意设置密码,具有较强的抗干扰能力,结构简单,使用方便,成本低,耗电少,具有普遍的应用价值。 相似文献
74.
网上资金结算系统对传统资金结算系统的发展具有良好的推动作用。文中分析了网上资金结算系统的结构,提出了数据传输过程中加密和解密的流程。结合该流程设计了服务器安全代理和用户端安全代理的数据流。以实现网上资金结算的安全性。 相似文献
75.
Recently, Courtois and Pieprzyk proposed a class of algebraic attacks on symmetric block ciphers that takes advantage of a
previously-unexploited property of substitution boxes, or s-boxes, in the round function. This paper gives a brief overview
of this ``overdefined system of equations' (OSE) attack and shows how the attack may be avoided through the use of round
functions constructed according to the CAST design procedure. Such round functions contain a variety of protection mechanisms,
including s-boxes of large dimension, a circular key-dependent rotation step, and combinations of operators from different
algebraic groups. 相似文献
76.
J.Y. Cheng C.A. Ross H.I. Smith E.L. Thomas 《Advanced materials (Deerfield Beach, Fla.)》2006,18(19):2505-2521
One of the key challenges in nanotechnology is to control a self‐assembling system to create a specific structure. Self‐organizing block copolymers offer a rich variety of periodic nanoscale patterns, and researchers have succeeded in finding conditions that lead to very long range order of the domains. However, the array of microdomains typically still contains some uncontrolled defects and lacks global registration and orientation. Recent efforts in templated self‐assembly of block copolymers have demonstrated a promising route to control bottom‐up self‐organization processes through top‐down lithographic templates. The orientation and placement of block‐copolymer domains can be directed by topographically or chemically patterned templates. This templated self‐assembly method provides a path towards the rational design of hierarchical device structures with periodic features that cover several length scales. 相似文献
77.
78.
79.
80.
S. Garcia A. Amrouche G. Mesmacque X. Decoopman C. Rubio 《International Journal of Fatigue》2005,27(10-12):1347
Fatigue damage accumulation of cold expanded hole in aluminum alloys used in land transportation components was investigated. Tests were carried out using pre-cracked SENT specimens and inserting an expanded hole at the crack tip. The degree of the cold expansion was chosen equal to 4.3%. Tests were performed in two and four block loading under constant amplitude. Two sequences were compared.The increasing and the decreasing magnitude were compared. The experimental results were compared to the damage calculated by the Miner's rule and a new simple fatigue damage indicator. This comparison shows that the ‘model of the damage stress’, which take into account of the loading history, yields a good estimation of the experimental results. Moreover, the error is minimized in comparison to the Miner's model. 相似文献