全文获取类型
收费全文 | 2084篇 |
免费 | 107篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 23篇 |
综合类 | 4篇 |
化学工业 | 527篇 |
金属工艺 | 45篇 |
机械仪表 | 50篇 |
建筑科学 | 41篇 |
矿业工程 | 7篇 |
能源动力 | 58篇 |
轻工业 | 120篇 |
水利工程 | 10篇 |
石油天然气 | 24篇 |
武器工业 | 1篇 |
无线电 | 188篇 |
一般工业技术 | 642篇 |
冶金工业 | 59篇 |
原子能技术 | 37篇 |
自动化技术 | 360篇 |
出版年
2024年 | 7篇 |
2023年 | 22篇 |
2022年 | 78篇 |
2021年 | 104篇 |
2020年 | 72篇 |
2019年 | 64篇 |
2018年 | 78篇 |
2017年 | 70篇 |
2016年 | 76篇 |
2015年 | 49篇 |
2014年 | 109篇 |
2013年 | 149篇 |
2012年 | 151篇 |
2011年 | 200篇 |
2010年 | 90篇 |
2009年 | 102篇 |
2008年 | 96篇 |
2007年 | 115篇 |
2006年 | 87篇 |
2005年 | 71篇 |
2004年 | 75篇 |
2003年 | 51篇 |
2002年 | 69篇 |
2001年 | 24篇 |
2000年 | 21篇 |
1999年 | 23篇 |
1998年 | 28篇 |
1997年 | 23篇 |
1996年 | 8篇 |
1995年 | 12篇 |
1994年 | 13篇 |
1993年 | 10篇 |
1992年 | 9篇 |
1991年 | 6篇 |
1990年 | 5篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1987年 | 4篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1973年 | 2篇 |
1972年 | 1篇 |
1965年 | 1篇 |
1958年 | 2篇 |
排序方式: 共有2196条查询结果,搜索用时 15 毫秒
101.
102.
Tomaž Javornik Igor Jelovčan S. Sheikh Muhammad Gorazd Kandus 《AEUE-International Journal of Electronics and Communications》2009,63(7):595-599
In the following paper we propose a new approach for extracting soft values from Mth order pulse position modulation (M-PPM). A new low-complexity algorithm is developed, where soft information for each data bit is calculated based on the power received within the PPM time slots. In order to decrease the computational complexity we simplify the calculation of the conditional probability of data vector a given that PPM symbol Y is received. The Monte Carlo simulations applied to analyze the properties of the algorithm for turbo-coded M-PPM transmission in free space optic communication systems show acceptable degradation of system performance with regard to system simplification. 相似文献
103.
Igor Matutinovi 《Energy Policy》2009,37(11):4251-4258
The key issues concerning oil exploitation are still open for discussion: there is no agreement about where we presently stand in the world oil extraction curve, what is its exact shape, and how far can oil price grow before it changes irreversibly the world economy and consumer behavior. The paper proposes an alternative scenario to the Hubbert's bell-shaped model of oil exploitation, based on more realistic assumptions regarding political agendas in oil-exporting countries and consumer behavior dynamics in oil-importing countries. Under this scenario, the joint impact of markets and public policy in oil importing countries together with “resource pragmatism” policy in oil-exporting countries allows for a less steep oil supply curve with a much fatter tail compared to the Hubbert's model. 相似文献
104.
Victor Prikhodko Igor Yarygin Vyacheslav Yarygin 《Microgravity science and technology》2009,21(Z1):277-281
We present the experimental research on the interaction of co-current gas flow with near-wall liquid film for gas velocities
up to 300 m/s. Local parameters of near-wall liquid film are measured by using capacity-type probes. It is shown that co-current
gas flow has strong influence on near-wall liquid film, leading to intensive wave formation, detachment of droplets from the
film surface and their entrainment by the gas flow. Thus it is shown that the relative amount of liquid carried away by co-current
gas flow is well characterized by Weber number of gas flow. A model for the motion of a film with co-current flow, connecting
a thickness and velocity of the film with value of shearing stress at gas-liquid boundary, is suggested. It is shown that
intensive wave formation leads to essential increase of the interphase friction value. 相似文献
105.
An argument is put forward to show that visual art may actually be translated into tactile objects that produce equivalent aesthetic experiences for blind or visually impaired people. This is shown by delineating the information required for such a translation in general, demonstrating that such a translation is already achievable from color vision to color vision and theoretically possible from spatial vision to spatial touch, and outlining that an analogous procedure could be applied to aesthetic experience. Limitations of such translations of visual works of art into tactile objects, and implications of such a procedure for artistic experience and education, are also mentioned. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
106.
It is often suggested in literature to use change in the effective elastic properties (stiffness loss) as an indicator of
reduction of strength due to defects such as cracks and pores. We argue that the key parameter is not the reduction of the
average (over the specimen) stiffness but its local minimal values caused by formation of defect clusters. These defect clusters can be identified by the emergence of spatial
gradients of elastic stiffness on a smaller scale. A convenient tool of detecting these gradients is provided by the elasticity-conductivity
connection: the electric conductance gradient is usually easier to measure than the stiffness gradient. This concept is supported
by computational and experimental results reported in two accompanying papers published in the present issue (by Sevostianov
et al and Caiulo and Kachanov). 相似文献
107.
Andrzej Banaszuk Vladimir A. Fonoberov Thomas A. Frewen Marin Kobilarov George Mathew Igor Mezic Alessandro Pinto Tuhin Sahai Harshad Sane Alberto Speranzon Amit SuranaAuthor vitae 《Annual Reviews in Control》2011,35(1):77-98
Development of robust dynamical systems and networks such as autonomous aircraft systems capable of accomplishing complex missions faces challenges due to the dynamically evolving uncertainties coming from model uncertainties, necessity to operate in a hostile cluttered urban environment, and the distributed and dynamic nature of the communication and computation resources. Model-based robust design is difficult because of the complexity of the hybrid dynamic models including continuous vehicle dynamics, the discrete models of computations and communications, and the size of the problem. We will overview recent advances in methodology and tools to model, analyze, and design robust autonomous aerospace systems operating in uncertain environment, with stress on efficient uncertainty quantification and robust design using the case studies of the mission including model-based target tracking and search, and trajectory planning in uncertain urban environment. To show that the methodology is generally applicable to uncertain dynamical systems, we will also show examples of application of the new methods to efficient uncertainty quantification of energy usage in buildings, and stability assessment of interconnected power networks. 相似文献
108.
The results of activity made in the framework of preparation of the experiment SAFIR (Single fin condensAtion: FIlm local measuRements) of European Space Agency are presented. First prototype of the test cell has been developed and tested. Confocal technique has been adopted for condensate film thickness measurements. Experiments on condensation of the liquid FC-72 have been carried out. Average heat transfer coefficient has been measured in the range of 880–1440 W/m2 K and compared to the Nusselt theory. 相似文献
109.
Experimental Study of Laminar Convective Condensation of Pure Vapor Inside an Inclined Circular Tube
Yuriy Lyulin Igor Marchuk Sergey Chikov Oleg Kabov 《Microgravity science and technology》2011,23(4):439-445
Convective condensation of pure ethanol vapor inside a smooth tube of inner diameter 4.8 mm and of length 200 mm is studied.
The experiments have been carried out at temperature 58°C corresponding to the pressure of 440 mbar, the vapor mass velocity
varying from 0.24 to 2.04 kg/(m2 s). The dependency of the Heat Transfer Coefficient (HTC) is investigated experimentally both subject to the temperature
difference between the saturated vapor and the wall and subject to the condenser inclination. The results show that the HTC
reduces with growth of the temperature difference. The dependency of the HTC on inclination has a maximum in the range 15°–35°
due to the complex gravity drainage mechanism of the condensed liquid. The results could be useful for development of compact
effective cooling systems for space and ground application. 相似文献
110.
A model has been developed for studying the effect of three hypothetical approaches in reducing electricity and energy demand in the Norwegian building stock: wide diffusion of thermal carriers, heat pumps and conservation measures, respectively. Combinations of these are also considered. The model has a demand side perspective, considers both residential and service sectors, and calculates energy flows from net to delivered energy. Energy demand is given by the product of activity and intensity matrices. The activity levels are defined for the stock and the new construction, renovation and demolition flows. The intensity properties are defined in archetypes, and are the result of different energy class and heating carriers share options. The scenarios are shaped by combining the activity flows with different archetypes. The results show that adopting conservation measures on a large scale does allow reducing both electricity and total energy demand from present day levels while the building stock keeps growing. The results also highlight the importance of making a clear distinction between the assumptions on intensity and activity levels. 相似文献