全文获取类型
收费全文 | 258609篇 |
免费 | 20468篇 |
国内免费 | 14461篇 |
专业分类
电工技术 | 36856篇 |
技术理论 | 25篇 |
综合类 | 29654篇 |
化学工业 | 15261篇 |
金属工艺 | 9029篇 |
机械仪表 | 20183篇 |
建筑科学 | 24614篇 |
矿业工程 | 11087篇 |
能源动力 | 9275篇 |
轻工业 | 7910篇 |
水利工程 | 8313篇 |
石油天然气 | 8653篇 |
武器工业 | 3988篇 |
无线电 | 24497篇 |
一般工业技术 | 14760篇 |
冶金工业 | 9353篇 |
原子能技术 | 2646篇 |
自动化技术 | 57434篇 |
出版年
2024年 | 893篇 |
2023年 | 2480篇 |
2022年 | 4821篇 |
2021年 | 6025篇 |
2020年 | 6347篇 |
2019年 | 4781篇 |
2018年 | 4352篇 |
2017年 | 6040篇 |
2016年 | 7088篇 |
2015年 | 8270篇 |
2014年 | 15698篇 |
2013年 | 13501篇 |
2012年 | 18573篇 |
2011年 | 19758篇 |
2010年 | 15034篇 |
2009年 | 15330篇 |
2008年 | 15538篇 |
2007年 | 19863篇 |
2006年 | 17952篇 |
2005年 | 16075篇 |
2004年 | 13229篇 |
2003年 | 12007篇 |
2002年 | 9280篇 |
2001年 | 7795篇 |
2000年 | 6470篇 |
1999年 | 5243篇 |
1998年 | 3904篇 |
1997年 | 3204篇 |
1996年 | 2825篇 |
1995年 | 2434篇 |
1994年 | 1988篇 |
1993年 | 1391篇 |
1992年 | 1173篇 |
1991年 | 828篇 |
1990年 | 713篇 |
1989年 | 594篇 |
1988年 | 444篇 |
1987年 | 273篇 |
1986年 | 174篇 |
1985年 | 179篇 |
1984年 | 153篇 |
1983年 | 116篇 |
1982年 | 93篇 |
1981年 | 94篇 |
1980年 | 77篇 |
1979年 | 75篇 |
1978年 | 49篇 |
1977年 | 45篇 |
1976年 | 42篇 |
1975年 | 28篇 |
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
51.
Tsuyoshi Takahashi Masahito Kitou Michio Asai Mitsuyasu Kido Tomio Chiba Junzou Kawakami Yoshiaki Matsui 《Electrical Engineering in Japan》1994,114(2):18-33
Power system control equipment needs higher sensitivity and operational reliability. Advanced voltage control equipment is needed for reducing the frequency of tap changes and improving the characteristics (the relationship between the actual voltage and reference voltage) of the voltage to meet today's power system requirements. However, these objectives are in a trade-off relationship. Studies of voltage control derived from a knowledge base suitable for electric power systems can satisfy these objectives using fuzzy inference. Compared with corresponding conventional equipment, the new equipment improved the deviation of 30 min average voltage of 30 percent. This paper describes the design concept of new voltage control equipment using fuzzy inference. In addition, field test results are described along with rules of fuzzy inference, membership functions, and the deviation of 30 min average voltage through detailed simulation. 相似文献
52.
In today's competitive business environment, it is important that customers are able to obtain their preferred items in the shops they visit, particularly for convenience store chains such as 7–Eleven where popular items are expected to be readily available on the shelves of the stores for buyers. To minimize the cost of running such store chains, it is essential that stocks be kept to a minimum and at the same time large varieties of popular items are available for customers. In this respect, the replenishment system needs to be able to cope with the taxing demands of minimal inventory but at the same time keeping large varieties of needed items. This paper proposes a replenishment system which is able to respond to the fluctuating demands of customers and provide a timely supply of needed items in a cost–effective way. The proposed system embraces the principle of fuzzy logic which is able to deal with uncertainties by virtue of its fuzzy rules reasoning mechanism, thereby leveraging the responsiveness of the entire replenishment system for the chain stores. To validate the feasibility of the approach, a case study has been conducted in an emulated environment with promising results. 相似文献
53.
54.
介绍了热水采暖系统运行及调整的注意事项,分析了立支管阀门、集气罐的作用,提出了使热水采暖系统的调节和集排气操作达到理想程度的有效措施,以实现良好的供暖效果。 相似文献
55.
This paper explains the manufacturing process of a composite train carbody with a sandwich composite structure for bodyshell and a stainless steel structure for the under frame. In addition, the structural behavior and safety of the composite carbody of the Korean tilting train was investigated by the static load tests. From the test results, the stiffness of the composite carbody met the specified design. In the aspect of strength, the maximum stress of the composite bodyshell was of 12.2% of strength of CF1263 carbon/epoxy. 相似文献
56.
57.
旋转式伽玛刀的辐射剂量学 总被引:4,自引:0,他引:4
旋转式伽玛刀的辐射剂量学指标的物理测试在放射性医疗设备投放医院正式临床使用前是必不可少的,是对设备及其附件的设计、加工制造、安装以及电气控制系统等的全面综合性检定。用电离室作辐射剂量学的绝对测量,用胶片法进行相对测量,给出了测量结果并进行了讨论。 相似文献
58.
电信管理及运营支撑是爱立信公司为公用电信网提供的有关管理及运营支撑功能的综合方案,本文介绍了其中的公网管理系统和蜂窝移动网络管理系统。 相似文献
59.
The condition of the surfaces is of crucial importance for the deuterium permeation through materials. In this work a study of the surface constants for the adsorption (σk1) and release (σk2) of deuterium under different surface conditions on the martensitic steel DIN 1.4914 (MANET) has been carried out. The growth of an oxide surface layer (Cr2O3) of about 25–30 nm in a MANET sample, heat treated in an oxidizing environment, compared to the bare MANET that have a ‘natural' oxide of about 5 nm has provoked a reduction of both the permeation rate and the recombination coefficient (about 3 orders of magnitude). In addition, the permeation governing process has changed from diffusion-limited to surface-limited. The measurements of the permeation rate of deuterium were performed by a gas-phase permeation technique over the temperature range 574–746 K and for deuterium driving pressures in the range from 3 to 105 Pa. 相似文献
60.
New small‐scale dispersed generation systems, such as fuel cells and micro gas turbines, have made remarkable advances lately and they will be applied practically in the near future. Although a large number of researches on the introduction of small‐scale dispersed generation systems have been carried out, only a small number of small‐scale dispersed generation systems are considered in these researches. Therefore, little is known about problems to be solved when a large number of small‐scale dispersed generation systems are introduced into electric power systems. This paper deals with a super‐distributed energy system that consists of a great number of dispersed generation systems such as fuel cells, micro gas turbines, and so on. The behavior of a customer with a dispersed generation system is simulated as the Ising model in statistical mechanics. The necessity of a distribution network in super‐distributed energy systems is discussed based on the Ising model. The feasibility of decentralized autonomous control using vicinity information is also investigated on the basis of stability analysis of the Hopfield neural network model. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 151(1): 43–55, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10368 相似文献