全文获取类型
收费全文 | 8986篇 |
免费 | 152篇 |
国内免费 | 7篇 |
专业分类
电工技术 | 226篇 |
综合类 | 1篇 |
化学工业 | 2049篇 |
金属工艺 | 263篇 |
机械仪表 | 173篇 |
建筑科学 | 437篇 |
矿业工程 | 88篇 |
能源动力 | 254篇 |
轻工业 | 210篇 |
水利工程 | 49篇 |
石油天然气 | 45篇 |
武器工业 | 1篇 |
无线电 | 1731篇 |
一般工业技术 | 1298篇 |
冶金工业 | 1180篇 |
原子能技术 | 163篇 |
自动化技术 | 977篇 |
出版年
2021年 | 60篇 |
2016年 | 60篇 |
2015年 | 88篇 |
2014年 | 137篇 |
2013年 | 650篇 |
2012年 | 133篇 |
2011年 | 207篇 |
2010年 | 195篇 |
2009年 | 257篇 |
2008年 | 218篇 |
2007年 | 189篇 |
2006年 | 236篇 |
2005年 | 219篇 |
2004年 | 196篇 |
2003年 | 213篇 |
2002年 | 242篇 |
2001年 | 235篇 |
2000年 | 219篇 |
1999年 | 213篇 |
1998年 | 243篇 |
1997年 | 234篇 |
1996年 | 227篇 |
1995年 | 196篇 |
1994年 | 229篇 |
1993年 | 211篇 |
1992年 | 218篇 |
1991年 | 188篇 |
1990年 | 215篇 |
1989年 | 219篇 |
1988年 | 167篇 |
1987年 | 149篇 |
1986年 | 137篇 |
1985年 | 105篇 |
1984年 | 113篇 |
1983年 | 93篇 |
1982年 | 97篇 |
1981年 | 112篇 |
1980年 | 94篇 |
1979年 | 96篇 |
1978年 | 94篇 |
1977年 | 105篇 |
1976年 | 85篇 |
1975年 | 97篇 |
1974年 | 74篇 |
1973年 | 73篇 |
1972年 | 89篇 |
1971年 | 78篇 |
1970年 | 78篇 |
1969年 | 68篇 |
1965年 | 68篇 |
排序方式: 共有9145条查询结果,搜索用时 15 毫秒
31.
A difficulty in reliability modeling is how to capture the impact of all of the various reliability defect types. The general approach to optimizing burn-in that we describe in this article addresses a multiple-defect environment. The approach has four main parts: (i) modeling the product's failure rate distribution, (ii) establishing the Pareto distribution of reliability defects, (iii) assessing the kinetic information of each reliability defect, and (iv) estimating the DPPM under product use conditions. This article compares and contrasts the acceleration effects of various extrinsic defects found in 130- and 90-nm CMOS technology products. 相似文献
32.
33.
Peter P. Mykytyn Jr. 《AI & Society》1989,3(2):133-141
Expert systems have been concerned with applications dealing with medical diagnosis, mineral exploration, and computer configuration, with some efforts relatively successful in achieving results at least as good as human experts. Today, much is being written about these systems and managerial decision-making activities in organizations and the positive impact that they can have in these situations. However, it appears that expert systems could become somewhat of a panacea for some organizational ailments as research, development, and marketing of them continues at a fast pace. What may be forgotten in this technological thrust is the individual decision maker and his/her unique style of decision making which could affect acceptance and use of these systems. Another important consideration is the attitude people have toward computers and computer systems, which along with decision-making styles could certainly affect expert system effectiveness and ultimate success in organizations. This paper provides a discussion of potential problems that could occur regarding individual decision making and attitudes and their relationships to these systems. 相似文献
34.
35.
Cinquemani P.L. Kuchta F.L. Hayes H.L. III Chavarria G.E. Lindler C.E. Jr. 《Power Delivery, IEEE Transactions on》2005,20(1):4-10
High-stress design 35-kV ethylene propylene rubber (EPR)-insulated cables with 1.14-mm (45-mil) wall reduction have been in service for more than ten years. In the mid 1990s, an extensive cable testing program was initiated to demonstrate that high-stress designs up to 4 kV/mm (101.6 V/mil) exhibit a significant electrical and mechanical safety margin to operate on typical utility network systems. Investigations were also undertaken to demonstrate the suitability of accessories for high-stress designs. This paper will present the results of six-year, long-term wet electrical testing conducted to demonstrate that with proper design, the aging performance of standard wall and high-stress design cables provide satisfactory results and suitable performance for the intended application. Additionally, utility field experience is presented on 35- and 15-kV cables operating at high stress. The experience for these 15-kV medium-voltage EPR cable designs employ the highest recommended stress for cables of this class, as well as taking into account the complete system performance. 相似文献
36.
Conclusion Because of the success of this project as measured by the favorable comments of the participants as well as the increased
search activity, the Council on the Humanities awarded an additional $1000 to continue the project in the spring of 1985.
As an added feature of the new proposal, a workshop is planned for chairs of the various humanities departments as well as
other interested humanists. The aim will be to encourage them and their colleagues to increase their involvement in automated
literature searching, as well as to encourage their graduate students to use the service. With continued support, greater
awareness of the service, and more extensive coverage of existing and future databases,3 a steady increase in computer-assisted bibliographic searching among humanists is definitely possible. 相似文献
37.
Although all-optical networks were being thought about almost ten years ago, until recently it would have been premature to talk about such networks as being truly usable. Now, ways of removing most of the roadblocks to practicality have come clearly into view. It is generally agreed that time-division packet switching in the form of asynchronous transfer mode (ATM) is likely to constitute the next generation of networking, both local and wide area; but what about the generation after that? While people are evolving SONET/ATM, the present Internet, and such emerging ambitions as the National Information Infrastructure (NII), in order to serve the needs anticipated for the next decade, optical fiber is being steadily installed at a rate of 700 miles per day in the United States alone. Furthermore, this resource is being extended steadily outward from the telco or cable provider backbone into customer premises, so that within the lifetime of the ATM generation, we may expect extremely rich fiber connectivity of a large number of homes and offices 相似文献
38.
In this paper, we present a technique for using an additional parallel neural network to provide adaptive enhancements to a basic fixed neural network-based nonlinear control system. This proposed parallel adaptive neural network control system is applicable to nonlinear dynamical systems of the type commonly encountered in many practical position control servomechanisms. Properties of the controller are discussed, and it is shown that if Gaussian radial basis function networks are used for the additional parallel neural network, uniformly stable adaptation is assured and the approximation error converges to zero asymptotically. In the paper, the effectiveness of the proposed parallel adaptive neural network control system is demonstrated in real-time implementation experiments for position control in a servomechanism with asymmetrical loading and changes in the load 相似文献
39.
Tabletability of five types of maltodextrin, a filler/binder excipient, was studied by testing their loading potentials with acetaminophen. The formulations consisted of excipient and acetaminophen at five different ratios and magnesium stearate at a 0.5% concentration. These mixtures were compacted employing an Integrated Compaction Research System at a constant punch velocity of 100 mm/sec. under varying applied pressures from 50 to 450 MPa. Compaction data were evaluated using the total work of compaction vs applied pressure plots whilst the post-compaction tests included the measurements of crushing force, disintegration time, and friability of the resulting tablets. Both the energy involved during the compaction of a formulation and the crushing force values of the resulting tablets decreased as the amount of the maltodextrin in a formulation was reduced. Maltodextrins exhibited adequate binding potential at acetaminophen drug loading levels of only up to twenty-five percent. The disintegration times of the tablets containing maltodextrins were generally prolonged and this was found to be due to the formation of a “gel” layer around the tablet which formed on immersion into water. The tabletability of maltodextrins were also compared to that of Fast-Flo lactose, and the compactability of these excipients were found to be similar. 相似文献
40.
Tannas L.E. Jr. 《Proceedings of the IEEE. Institute of Electrical and Electronics Engineers》1994,82(4):499-509
The evolution in performance and manufacturability of liquid-crystal displays has created a new reality in the electronic information displays industry. LCD's now outnumber all other flat-panel displays in production volume, by more than two orders of magnitude. LCD's may equal CRT's in market sales by the year 2000. However, LCD's are still an order of magnitude more expensive than comparable performing CRT's. LCD's are enabling new products, such as personal digital assistants, moving map navigators, picture telephones, etc., which could not he readily done with CRTs because of their size and sensitivity to ambient illuminations. The LCD technology in various modes, from passive twisted nematic to active matrix, is being used in all product sizes, from the 0.7-in camcorder viewfinder to the 14-in full-color display with XGA resolution. Full color is very important in future products and any flat-panel display technology without it will be relegated to niche markets 相似文献