全文获取类型
收费全文 | 112073篇 |
免费 | 10428篇 |
国内免费 | 6170篇 |
专业分类
电工技术 | 7759篇 |
技术理论 | 2篇 |
综合类 | 8402篇 |
化学工业 | 17333篇 |
金属工艺 | 6676篇 |
机械仪表 | 7605篇 |
建筑科学 | 9053篇 |
矿业工程 | 3810篇 |
能源动力 | 2971篇 |
轻工业 | 7942篇 |
水利工程 | 2340篇 |
石油天然气 | 6099篇 |
武器工业 | 1068篇 |
无线电 | 12867篇 |
一般工业技术 | 12117篇 |
冶金工业 | 4894篇 |
原子能技术 | 1299篇 |
自动化技术 | 16434篇 |
出版年
2024年 | 522篇 |
2023年 | 1672篇 |
2022年 | 3424篇 |
2021年 | 4625篇 |
2020年 | 3449篇 |
2019年 | 2838篇 |
2018年 | 3157篇 |
2017年 | 3569篇 |
2016年 | 3257篇 |
2015年 | 4831篇 |
2014年 | 5929篇 |
2013年 | 7096篇 |
2012年 | 7922篇 |
2011年 | 8577篇 |
2010年 | 7812篇 |
2009年 | 7709篇 |
2008年 | 7460篇 |
2007年 | 7143篇 |
2006年 | 6585篇 |
2005年 | 5693篇 |
2004年 | 3806篇 |
2003年 | 3173篇 |
2002年 | 2974篇 |
2001年 | 2610篇 |
2000年 | 2289篇 |
1999年 | 2186篇 |
1998年 | 1532篇 |
1997年 | 1374篇 |
1996年 | 1181篇 |
1995年 | 961篇 |
1994年 | 814篇 |
1993年 | 580篇 |
1992年 | 465篇 |
1991年 | 335篇 |
1990年 | 270篇 |
1989年 | 213篇 |
1988年 | 183篇 |
1987年 | 112篇 |
1986年 | 89篇 |
1985年 | 41篇 |
1984年 | 47篇 |
1983年 | 21篇 |
1982年 | 31篇 |
1981年 | 22篇 |
1980年 | 26篇 |
1979年 | 10篇 |
1978年 | 8篇 |
1976年 | 7篇 |
1959年 | 7篇 |
1951年 | 13篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
11.
化工企业环境因素的评价 总被引:1,自引:0,他引:1
化工企业环境因素评价是建立环境管理体系的核心任务,化工企业生产过程的特点决定了其环境因素数量多、环境影响大、识别评价难、控制难度大。本文介绍了化工企业环境因素评价的技术方法和过程,可以为提高环境因素评价的科学性、客观性和充分性提供参考。 相似文献
12.
我国建筑涂料技术进步简评 总被引:1,自引:1,他引:0
从以下诸方面简述我国建筑涂料的技术进步:⑴新品种涂料的研制开发;⑵加强对配套材料及施工技术的研究;⑶超细填料在涂料中的应用;⑷计算机自动配色技术;⑸产品标准的修订;⑹建筑涂料的实用范围扩大。 相似文献
13.
浅谈高层建筑火灾扑救 总被引:3,自引:0,他引:3
杨冰峰 《消防技术与产品信息》2002,(11):28-31
前言伴随着我国经济建设的迅速发展 ,高层建筑已在各大城市大量涌现。大量的高层建筑 ,既为城市的经济发展增添了繁荣的氛围 ,同时又给消防安全提出了新的课题。近年来 ,高层建筑所引发的火灾已成为全世界关注的一个难题。据统计 ,1999年全国共发生高层建筑火灾 112 2起 ,而 2 0 0 0年则猛增到 184 32起。因此 ,加强对高层建筑火灾扑救的研究 ,对缔造良好的消防环境 ,确保经济和社会稳定至关重要。本文仅是作者的一些浅见 ,希望能有可取之处与大家分享。18世纪末至 19世纪 ,欧洲和美国的的工业革命带来了生产力的发展与经济的繁荣。这个时期… 相似文献
14.
15.
Haitao Zhang Zonghai Chen Yongji Wang Ming Li Ting Qin 《International Journal of Adaptive Control and Signal Processing》2006,20(2):53-76
Laguerre Functional Model has many advantages such as good approximation capability for the variances of system time‐delay, order and other structural parameters, low computational complexity, and the facility of online parameter identification, etc., so this model is suitable for complex industrial process control. A series of successful applications have been gained in linear and non‐linear predictive control fields by the control algorithm based on Laguerre Functional Model, however, former researchers have not systemically brought forward the theoretical analyses of the stability, robustness, and steady‐state performance of this algorithm, which are the keys to guarantee the feasibility of the control algorithm fundamentally. Aimed at this problem, we introduce the principles of the Incremental Mode Linear Laguerre Predictive Control (IMLLPC) algorithm, and then systemically propose the theoretical analyses and proofs of the stability and robustness of the algorithm, in addition, we also put forward the steady‐state performance analysis. At last, the control performances of this algorithm on two different physical industrial plants are presented in detail, and a number of experimental results validate the feasibility and superiority of IMLLPC algorithm. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
16.
The Tikhonov regularisation technique is widely used in the solution of inverse scattering problems. One of the difficulties in applying this technique is the proper selection of the associated regularisation parameter. Based on a stochastic model of the reconstruction process, a simple method is presented for selecting this parameter for an efficient implementation of various microwave imaging methods 相似文献
17.
Jyh-Ming Wang Sung-Chuan Fang Wu-Shiung Feng 《Solid-State Circuits, IEEE Journal of》1994,29(7):780-786
Two new methods are proposed to implement the exclusive-OR and exclusive-NOR functions on the transistor level. The first method uses non-complementary signal inputs and the least number of transistors. The other one improves the performance of the prior method but two more transistors are utilized. Both of them have been fully simulated by HSPICE on a SUN SPARC 2 workstation 相似文献
18.
A powerful concept to cope with resource limitations and information redundancy in wireless sensor networks is the use of collaboration groups to distill information within the network and suppress unnecessary activities. When the phenomena to be monitored have large geographical extents, it is not obvious how to define these collaboration groups. This article presents the application of geometric duality to form such groups for sensor selection and non-local phenomena tracking. Using a dual-space transformation, which maps a non-local phenomenon (e.g., the edge of a half-plane shadow) to a single point in the dual space and maps locations of distributed sensor nodes to a set of lines that partitions the dual space, one can turn off the majority of the sensors to achieve resource preservation without losing detection and tracking accuracy. Since the group so defined may consist of nodes that are far away in physical space, we propose a hierarchical architecture that uses a small number of computationally powerful nodes and a massive number of power constrained motes. By taking advantage of the continuity of physical phenomena and the duality principle, we can greatly reduce the power consumption in non-local phenomena tracking and extend the lifetime of the network. 相似文献
19.
Since most end-of-life electronics equipment contain hazardous materials such as lead solder alloys or lead-impregnated glass, it is important to divert them from landfills. For end-of-life products that are not repairable and do not contain reusable parts, bulk recycling is an alternative to recover base materials. In this paper, we contrast production and recycling planning and distribution decisions, activities, and costs. We reveal that while a traditional production facility connects suppliers and customers, a recycling facility connects both "input" and "output" customers. As a result, decisions in short-term bulk recycling planning include what products to accept, what products to process and reprocess, and what products to carry in inventory. Many recyclers set prices to receive "input" based on experience. For various prices to receive "input", we use a new analytical model to investigate the sensitivity of the short-term bulk recycling planning decisions in products from two different sources: industrial returns versus residential returns. The results of the case study show that different decisions are recommended for the industrial returns versus the residential returns when the total quantity of the incoming products is equal. 相似文献
20.
从能源、市场和效益角度入手,浅显分析了玻璃企业现状,提出了企业应根据市场变化调整决策,利用现代资 本市场建立现代化企业制度,将油价大幅上升做为企业获取巨额利润的重大机遇,保持企业稳步长久发展。 相似文献