全文获取类型
收费全文 | 185094篇 |
免费 | 15600篇 |
国内免费 | 12110篇 |
专业分类
电工技术 | 29605篇 |
技术理论 | 7篇 |
综合类 | 17177篇 |
化学工业 | 11276篇 |
金属工艺 | 7382篇 |
机械仪表 | 16312篇 |
建筑科学 | 15481篇 |
矿业工程 | 7674篇 |
能源动力 | 5180篇 |
轻工业 | 5236篇 |
水利工程 | 5631篇 |
石油天然气 | 9794篇 |
武器工业 | 2780篇 |
无线电 | 13380篇 |
一般工业技术 | 8834篇 |
冶金工业 | 8317篇 |
原子能技术 | 1304篇 |
自动化技术 | 47434篇 |
出版年
2024年 | 765篇 |
2023年 | 2094篇 |
2022年 | 3450篇 |
2021年 | 4258篇 |
2020年 | 5107篇 |
2019年 | 4009篇 |
2018年 | 3577篇 |
2017年 | 5200篇 |
2016年 | 5785篇 |
2015年 | 6341篇 |
2014年 | 12093篇 |
2013年 | 10716篇 |
2012年 | 13269篇 |
2011年 | 14270篇 |
2010年 | 10810篇 |
2009年 | 11127篇 |
2008年 | 11021篇 |
2007年 | 13581篇 |
2006年 | 12311篇 |
2005年 | 10751篇 |
2004年 | 8923篇 |
2003年 | 7925篇 |
2002年 | 6405篇 |
2001年 | 5344篇 |
2000年 | 4588篇 |
1999年 | 3726篇 |
1998年 | 2864篇 |
1997年 | 2519篇 |
1996年 | 2031篇 |
1995年 | 1653篇 |
1994年 | 1390篇 |
1993年 | 995篇 |
1992年 | 795篇 |
1991年 | 610篇 |
1990年 | 490篇 |
1989年 | 420篇 |
1988年 | 285篇 |
1987年 | 180篇 |
1986年 | 136篇 |
1985年 | 125篇 |
1984年 | 170篇 |
1983年 | 126篇 |
1982年 | 125篇 |
1981年 | 83篇 |
1980年 | 59篇 |
1979年 | 67篇 |
1978年 | 50篇 |
1977年 | 51篇 |
1964年 | 18篇 |
1959年 | 14篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
111.
112.
113.
The adaptive Generalized Predictive Controller (Clarke et al., 1987a, b) is capable of controlling plants with variable dead-time, unknown model orders and unstable poles and zeros. This paper shows how the GPC control law can be written in an equivalent general linear transfer function form which simplifies closed-loop (eg. root locus) analysis. Three recommended strategies for selecting the design parameters during the commissioning stage allow the user to adjust the closed-loop speed of response on-line using only a single active tuning parameter. Experimental runs confirm the ability of adaptive GPC to provide a consistent closed-loop response in spite of large process changes. 相似文献
114.
Six distillation column models have been used in studies of the usefulness of the Inverse Nyquist Array (INA) method for design of dual composition control for distillation. Five of the column models are experimental, one describing an industrial column, the others four pilot plants. One column model is obtained by modeling from first principles.
The control strategies investigated and compared are multiloop SISO, 2-way decoupling and l-way decoupling. The control variables are the standard ones, i.e. reflux flow and boilup.
In most of the cases INA has been found to be a useful tool for design of the loops and for comparison of the different control approaches. INA has also been found to be useful for simultaneous tuning of the decouplers and the feedback controllers.
For 2-way decoupling the criterion to minimize interaction at the critical frequency for each primary feedback loop has been found useful in most, but not all, cases. The scheme can be designed by pure gains in the decouplers and there is no reason to introduce dynamics into the decouplers—the systems studied are already sufficiently rich in dynamics.
INA has been found to be a suitable vehicle for the choice between the two possible l-way decoupling schemes.
With the design approach taken, l-way decoupling has been found to provide considerably better control quality than 2-way decoupling in two of the six systems, the differences in control quality being small in the other cases.
The effect of model mismatching on the results, caused e.g. by process nonlinearities, is discussed and simple rules to decrease the parameter sensitivity for 2-way decoupling schemes are given. When model mismatching is considered, the advantage of l-way decoupling over 2-way decoupling seems to increase.
One deficiency of the INA design as used in this paper is that it does not single out the design which is to be preferred on the grounds of robustness. 相似文献
The control strategies investigated and compared are multiloop SISO, 2-way decoupling and l-way decoupling. The control variables are the standard ones, i.e. reflux flow and boilup.
In most of the cases INA has been found to be a useful tool for design of the loops and for comparison of the different control approaches. INA has also been found to be useful for simultaneous tuning of the decouplers and the feedback controllers.
For 2-way decoupling the criterion to minimize interaction at the critical frequency for each primary feedback loop has been found useful in most, but not all, cases. The scheme can be designed by pure gains in the decouplers and there is no reason to introduce dynamics into the decouplers—the systems studied are already sufficiently rich in dynamics.
INA has been found to be a suitable vehicle for the choice between the two possible l-way decoupling schemes.
With the design approach taken, l-way decoupling has been found to provide considerably better control quality than 2-way decoupling in two of the six systems, the differences in control quality being small in the other cases.
The effect of model mismatching on the results, caused e.g. by process nonlinearities, is discussed and simple rules to decrease the parameter sensitivity for 2-way decoupling schemes are given. When model mismatching is considered, the advantage of l-way decoupling over 2-way decoupling seems to increase.
One deficiency of the INA design as used in this paper is that it does not single out the design which is to be preferred on the grounds of robustness. 相似文献
115.
浅谈一次盐水的工艺指标控制 总被引:2,自引:0,他引:2
介绍了一次盐水的各项工艺指标对生产的影响以及稳定控制这些指标的方法,强调了在生产中控制好一次盐水的工艺指标是影响产品质量及离子交换膜使用寿命的关键。 相似文献
116.
117.
We present a simple and fast algorithm to test the thermodynamic stability and determine the necessary chemical environment for the production of a multiternary material, relative to competing phases and compounds formed from the constituent elements. If the material is found to be stable, the region of stability, in terms of the constituent elemental chemical potentials, is determined from the intersection points of hypersurfaces in an (n−1)-dimensional chemical potential space, where n is the number of atomic species in the material. The input required is the free energy of formation of the material itself, and that of all competing phases. Output consists of the result of the test of stability, the intersection points in the chemical potential space and the competing phase to which they relate, and, for two- and three-dimensional spaces, a file which may be used for visualization of the stability region. We specify the use of the program by applying it both to a ternary system and to a quaternary system. The algorithm automates essential analysis of the thermodynamic stability of a material. This analysis consists of a process which is lengthy for ternary materials, and becomes much more complicated when studying materials of four or more constituent elements, which have become of increased interest in recent years for technological applications such as energy harvesting and optoelectronics. The algorithm will therefore be of great benefit to the theoretical and computational study of such materials. 相似文献
118.
针对炭素制品生产过程产生的粉尘、沥青烟气、噪声等主要涉及工业卫生及环境保护等方面的问题进行剖析,并对治理方法做了简要的介绍。 相似文献
119.
The dynamic Characteristics of a Fluidized Catalytic Cracking Process are examined over a wide range of operating conditions. A novel Order of Magnitude Approach is introduced to successfully provide physical insight into the cause and effect relationship between operating conditions and dynamic characteristics. It is shown that the original five-dimensional dynamic model is characterized by three fast time constants and two slow ones that dominate the dynamic responses. The two most important time constants are expressed as explicit functions of the operating conditions. These formulas correctly indicate in which parameter regions the open loop response is oscillatory (underdamped) or nonoscillatory (overdamped). Extensive process variables, that are either flow or capacity, related are defined in order to provide an approximate physical meaning for the dynamic modes of the system. It is shown that the two slow modes of the process are related to the enthalpy content of the regenerator and the sensible heat content of the catalyst phase in both the reactor and regenerator. 相似文献
120.
《Journal of Process Control》2014,24(2):389-398
A hierarchical two-layer control algorithm is developed for a class of hybrid (discrete-continuous dynamic) systems to support economically optimal operation of batch or continuous processes with a predefined production schedule. For this class of hybrid systems, the optimal control moves as well as the controlled switching times between two adjacent modes are determined online. In contrast to closely related schemes for integrated scheduling and control, the sequence of modes is not optimized. On the upper layer, the economic optimal control problem is solved rigorously by a slow hybrid economic model predictive controller at a low sampling rate. On the lower layer, a fast hybrid neighboring-extremal controller is based on the same economic optimal control problem as the slow controller to ensure consistency between both layers. The fast neighboring-extremal controller updates rather than tracks the optimal trajectories from the upper layer to account for disturbances. Consequently, the fast controller steers the process to its operational bounds under disturbances and the economic potential of the process is exploited anytime. The suggested two-layer control algorithm provides fully consistent control action on the fast and slow time-scale and thus avoids performance degradation and even infeasibilities which are commonly encountered if inconsistent optimal control problems are formulated and solved. 相似文献