全文获取类型
收费全文 | 64278篇 |
免费 | 6780篇 |
国内免费 | 4415篇 |
专业分类
电工技术 | 4664篇 |
技术理论 | 4篇 |
综合类 | 6090篇 |
化学工业 | 8878篇 |
金属工艺 | 4457篇 |
机械仪表 | 4408篇 |
建筑科学 | 4767篇 |
矿业工程 | 2440篇 |
能源动力 | 1825篇 |
轻工业 | 6591篇 |
水利工程 | 1783篇 |
石油天然气 | 3331篇 |
武器工业 | 794篇 |
无线电 | 6834篇 |
一般工业技术 | 6078篇 |
冶金工业 | 2830篇 |
原子能技术 | 1038篇 |
自动化技术 | 8661篇 |
出版年
2024年 | 421篇 |
2023年 | 1186篇 |
2022年 | 2605篇 |
2021年 | 3295篇 |
2020年 | 2520篇 |
2019年 | 1748篇 |
2018年 | 1966篇 |
2017年 | 2124篇 |
2016年 | 1872篇 |
2015年 | 2935篇 |
2014年 | 3475篇 |
2013年 | 4144篇 |
2012年 | 4850篇 |
2011年 | 5167篇 |
2010年 | 4686篇 |
2009年 | 4414篇 |
2008年 | 4674篇 |
2007年 | 4341篇 |
2006年 | 3814篇 |
2005年 | 3149篇 |
2004年 | 2221篇 |
2003年 | 1692篇 |
2002年 | 1657篇 |
2001年 | 1457篇 |
2000年 | 1206篇 |
1999年 | 930篇 |
1998年 | 555篇 |
1997年 | 466篇 |
1996年 | 400篇 |
1995年 | 345篇 |
1994年 | 281篇 |
1993年 | 189篇 |
1992年 | 164篇 |
1991年 | 98篇 |
1990年 | 95篇 |
1989年 | 80篇 |
1988年 | 44篇 |
1987年 | 46篇 |
1986年 | 30篇 |
1985年 | 20篇 |
1984年 | 10篇 |
1983年 | 15篇 |
1982年 | 4篇 |
1981年 | 13篇 |
1980年 | 20篇 |
1979年 | 10篇 |
1978年 | 2篇 |
1959年 | 26篇 |
1953年 | 1篇 |
1951年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Yixing Tian Huiling Liu Brian W.Sheldon Thomas J.Webster Sichen Yang Huilin Yang Lei Yang 《材料科学技术学报》2019,35(5):817-823
Nanostructured diamond have potential applications in many biomedical related fields and demonstrated extraordinary capacity to influence cellular responses. Studying the surface property of nanodiamond and its influence to protein adsorption and subsequent cellular responses along with the mechanism behind such capacity becomes more important. Here the role of surface energy associated with nanostructured diamond in modulating fibronectin and osteoblast(OB, bone forming cells) responses was investigated. Nanocrystalline diamond(NCD) and submicron crystalline diamond(SMCD) films with controllable surface energy were prepared by microwave-enhanced plasma chemical vapor deposition(MPCVD) techniques. Fibronectin adsorption on the diamond films with varied surface energy values was measured via the enzyme-linked immunosorbent assay(ELISA) and the relationship between the surface energy and fibronectin adsorption was studied. The result indicated that fibronectin adsorption on nanostructured surfaces was closely related to both surface energy and material microstructures. The spreading and migration of OB aggregates(each containing 30–50 cells) on the NCD with varied surface energy values were also studied. The result indicates a correlation between the cell spreading and migration on nanodiamond and the surface energy of nanostructured surface. 相似文献
82.
Internet of Vehicles (IoV) applications integrating with edge computing will significantly drive the growth of IoV. However, the contradiction between the high-speed mobility of vehicles, the delay sensitivity of corresponding IoV applications and the limited coverage and resource capacity of distributed edge servers will pose challenges to the service continuity and stability of IoV applications. IoV application migration is a promising solution that can be supported by application containerization, a technology forseamless cross-edge-server application migration without user perception. Therefore, this paper proposes the container-based IoV edge application migration mechanism, consisting of three parts. The first is the migration trigger determination algorithm for cross-border migration and service degradation migration, respectively, based on trajectory prediction and traffic awareness to improve the determination accuracy. The second is the migration target decision calculation model for minimizing the average migration time and maximizing the average service time to reduce migration times and improve the stability and adaptability of migration decisions. The third is the migration decision algorithm based on the improved artificial bee colony algorithm to avoid local optimal migration decisions. Simulation results show that the proposed migration mechanism can reduce migration times, reduce average migration time, improve average service time and enhance the stability and adaptability of IoV application services. 相似文献
84.
85.
Tian Y Shumway BR Gao W Youngbull C Holl MR Johnson RH Meldrum DR 《Sensors and actuators. B, Chemical》2010,150(2):579-587
Oxygen sensing films were synthesized by a chemical conjugation of functional platinum porphyrin probes in silica gel, polystyrene (PS), and poly(2-hydroxyethyl methacrylate) (PHEMA) matrices. Responses of the sensing films to gaseous oxygen and dissolved oxygen were studied and the influence of the matrices on the sensing behaviors was investigated. Silica gel films had the highest fluorescence intensity ratio from deoxygenated to oxygenated environments and the fastest response time to oxygen. PHEMA films had no response to gaseous oxygen, but had greater sensitivity and a faster response time for dissolved oxygen than those of PS films. The influence of matrices on oxygen response, sensitivity and response time was discussed. The influence is most likely attributed to the oxygen diffusion abilities of the matrices. Since the probes were chemically immobilized in the matrices, no leaching of the probes was observed from the sensing films when applied in aqueous environment. One sensing film made from the PHEMA matrix was used to preliminarily monitor the oxygen consumption of Escherichia coli (E. coli) bacteria. E. coli cell density and antibiotics ampicillin concentration dependent oxygen consumption was observed, indicating the potential application of the oxygen sensing film for biological application. 相似文献
86.
为满足非接触化、小型化、集成化、数字化、智能化等现代检测技术的发展要求,从成本、工作原理、灵敏度等方面综合考虑,现采用以光电定位模块为核心的光电定位技术,以无线传感器网络作为数据传输与管理的技术手段,构建了无线光电定位网络,并进行了实验分析.可实现多点实时监测、异地显示测量数据、数据网络化管理等特殊需求;涵盖了多学科领... 相似文献
87.
Jialiang Sun Qiang Tian Haiyan Hu 《Structural and Multidisciplinary Optimization》2017,55(4):1159-1177
A topology optimization methodology is proposed for the flexible multibody system undergoing both large overall motion and large deformation. The system of concern is modeled via the absolute nodal coordinate formulation. The equivalent static load method is employed to transform the topology optimization of the nonlinear dynamic response of the system into a static one, and evaluated to adapt to the absolute nodal coordinate formulation by splitting the elastic deformations of the flexible components from the overall motions of those components. During the static topology optimization, the material interface is implicitly described as the zero level set of a higher-dimensional scalar function. Then, the semi-implicit level set method with the additive operator splitting algorithm is employed to solve the corresponding Hamilton-Jacobi partial differential equation. In addition, the expert evaluation method of weights based on the grey theory is utilized to define the objective function, and a modified augmented Lagrange multiplier method is proposed to treat the inequality volume constraint so as to avoid the oscillation and drift of the volume. Finally, two numerical examples are provided to validate the proposed methodology. 相似文献
88.
网络机器人(Web Robo)t是一种自动化获取网页数据的程序。实践中使用对特定主题感兴趣的网络机器人获取数据,与数据库中数据进行比对,得出有用的结果。 相似文献
89.
随着大型离散制造业的竞争日益激烈,提高生产效率变得越来越重要。实施MES(Manufacturing Execution System)是提高竞争力的一个比较好的解决方案,而网络通信畅通是实施MES的关键基础。针对大型离散制造业车间的行业特点和实际环境,引入了移动自组织网络(MANET,Mobile Ad hoc Network)作为通信的网络。由于MANET是不依赖固定基础设施、无中心控制、动态拓扑的动态无线通讯网络,研究基于实际环境的MANET的可靠性对于网络的部署和调整就显得非常有现实意义。基于实际制造业车间环境,给出了面向作业型制造业生产模式的MANAET可靠性分析模型(ERMWT,Embedded Reliability Model on Working Table)。 相似文献
90.
Xiaofeng Chen Qianhong Wu Haibo Tian Byoungcheon Lee Kwangjo Kim 《Information Sciences》2011,181(8):1493-1502
It is considered to be the most suitable solution for large scale elections to design an electronic voting scheme using blind signatures and anonymous channels. Based on this framework, Okamoto first proposed a receipt-free voting scheme [30] for large scale elections. However, in the following paper, Okamoto [31] proved that the scheme [30] was not receipt-free and presented two improved schemes. One scheme requires the help of the parameter registration committee and the other needs a stronger physical assumption of the voting booth. In this paper, we utilize the double-trapdoor commitment to propose a new receipt-free voting scheme based on blind signatures for large scale elections. Neither the parameter registration committee nor the voting booth is required in our scheme. We also present a more efficient zero-knowledge proof for secret permutation. Therefore, our scheme is much more efficient than Okamoto’s schemes [30] and [31] with the weaker physical assumptions. Moreover, we prove that our scheme can achieve the desired security properties. 相似文献