全文获取类型
收费全文 | 16926篇 |
免费 | 672篇 |
国内免费 | 22篇 |
专业分类
电工技术 | 264篇 |
综合类 | 22篇 |
化学工业 | 3192篇 |
金属工艺 | 279篇 |
机械仪表 | 347篇 |
建筑科学 | 485篇 |
矿业工程 | 68篇 |
能源动力 | 327篇 |
轻工业 | 1092篇 |
水利工程 | 110篇 |
石油天然气 | 50篇 |
无线电 | 1547篇 |
一般工业技术 | 3250篇 |
冶金工业 | 4102篇 |
原子能技术 | 187篇 |
自动化技术 | 2298篇 |
出版年
2023年 | 169篇 |
2022年 | 403篇 |
2021年 | 465篇 |
2020年 | 316篇 |
2019年 | 291篇 |
2018年 | 350篇 |
2017年 | 310篇 |
2016年 | 420篇 |
2015年 | 347篇 |
2014年 | 520篇 |
2013年 | 733篇 |
2012年 | 710篇 |
2011年 | 847篇 |
2010年 | 617篇 |
2009年 | 617篇 |
2008年 | 658篇 |
2007年 | 647篇 |
2006年 | 516篇 |
2005年 | 451篇 |
2004年 | 407篇 |
2003年 | 362篇 |
2002年 | 333篇 |
2001年 | 270篇 |
2000年 | 276篇 |
1999年 | 325篇 |
1998年 | 934篇 |
1997年 | 610篇 |
1996年 | 479篇 |
1995年 | 315篇 |
1994年 | 288篇 |
1993年 | 354篇 |
1992年 | 201篇 |
1991年 | 195篇 |
1990年 | 190篇 |
1989年 | 195篇 |
1988年 | 187篇 |
1987年 | 156篇 |
1986年 | 169篇 |
1985年 | 163篇 |
1984年 | 124篇 |
1983年 | 121篇 |
1982年 | 106篇 |
1981年 | 92篇 |
1980年 | 89篇 |
1979年 | 97篇 |
1978年 | 107篇 |
1977年 | 134篇 |
1976年 | 237篇 |
1975年 | 85篇 |
1974年 | 72篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
12.
The aim of this paper is to give a general quantitative requirement which the loop gain must satisfy in order to stabilize a given unstable (possibly nonlinear and time-varying) plant, namely that the gain must exceed one. 相似文献
13.
Russel B. Miller Isaac M. Horowitz Constantine H. Houpis A. Finley Barfield 《国际强度与非线性控制杂志
》1994,4(1):211-230
》1994,4(1):211-230
Nonlinear quantitative feedback theory (QFT) and pilot compensation techniques are used to design a 2 × 2 flight control system for the YF-16 aircraft over a large range of plant uncertainty. The design is based on numerical input-output time histories generated with a FORTRAN implemented nonlinear simulation of the YF-16. The first step of the design process is the generation of a set of equivalent linear time-invariant (LTI) plant models to represent the actual nonlinear plant. It has been proven that the solution to the equivalent plant problem is guaranteed to solve the original nonlinear problem. Standard QFT techniques are then used in the design synthesis based on the equivalent plant models. A detailed mathematical development of the method used to develop these equivalent LTI plant models is provided. After this inner-loop design, pilot compensation is developed to reduce the pilot's workload. This outer-loop design is also based on a set of equivalent LTI plant models. This is accomplished by modelling the pilot with parameters that result in good handling qualities ratings, and developing the necessary compensation to force the desired system responses. 相似文献
14.
15.
Bloomfield R.E. Guerra S. Miller A. Masera M. Weinstock C.B. 《Security & Privacy, IEEE》2006,4(3):66-68
Critical systems are aptly named - from electric power to water and gas to the telephone system and the Internet, they're all critical to some aspect of our daily lives. We're a networked society and as such, it's important to both know whether critical systems are trustworthy and be able to communicate, review, and debate the level of trust achieved in them. In the safety domain, explicit safety cases are increasingly required by law, regulations, and standards. In this article, we outline what a small, international group of experts, spanning various disciplines in safety, security, reliability, and critical infrastructure, been doing with the International Working Group on Assurance Cases (for Security), what we hope to achieve, and where we go next. 相似文献
16.
The benefits of adhesively bonded structures are well known. However, the most significant factor limiting the extensive application of metal bonding in primary aerospace structures is the prevailing lack of confidence in its long term durability under hostile environmental conditions.1,2 相似文献
17.
18.
19.
During large scale wildfires, suppression activities are carried out under the direction of an Incident Management Team (IMT). The aim of the research was to increase understanding of decision processes potentially related to IMT effectiveness. An IMT comprises four major functions: Command, Operations, Planning, and Logistics. Four methodologies were used to study IMT processes: computer simulation experiments; analyses of wildfire reports; interviews with IMT members; and cognitive ethnographic studies of IMTs. Three processes were important determinants of IMT effectiveness: information management and cognitive overload; matching component function goals to overall goals; and team metacognition to detect and counter task‐disruptive developments. These processes appear to be complex multi‐person analogues of individual Incident Command processes identified previously. The findings have implications for issues such as: creating IMTs; training IMTs; managing IMTs; and providing decision support to IMTs. 相似文献
20.
Jonathan P. Belnoue Giang D. Nguyen Alexander M. Korsunsky 《International Journal of Fracture》2007,144(1):53-60
This paper presents a new 1-D non-local damage-plasticity deformation model for ductile materials. It uses the thermodynamic
framework described in Houlsby and Puzrin (2000) and holds, nevertheless, some similarities with Lemaitre’s (1971) approach.
A 1D finite element (FE) model of a bar fixed at one end and loaded in tension at the other end is introduced. This simple
model demonstrates how the approach can be implemented within the finite element framework, and that it is capable of capturing
both the pre-peak hardening and post-peak softening (generally responsible for models instability) due to damage-induced stiffness
and strength reduction characteristic of ductile materials. It is also shown that the approach has further advantages of achieving
some degree of mesh independence, and of being able to capture deformation size effects. Finally, it is illustrated how the
model permits the calculation of essential work of rupture (EWR), i.e. the specific energy per unit cross-sectional area that
is needed to cause tensile failure of a specimen. 相似文献