首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   1356篇
  免费   37篇
  国内免费   4篇
电工技术   79篇
综合类   3篇
化学工业   220篇
金属工艺   34篇
机械仪表   24篇
建筑科学   19篇
能源动力   54篇
轻工业   77篇
水利工程   7篇
石油天然气   1篇
无线电   188篇
一般工业技术   237篇
冶金工业   359篇
原子能技术   20篇
自动化技术   75篇
  2023年   6篇
  2022年   15篇
  2021年   35篇
  2020年   9篇
  2019年   18篇
  2018年   26篇
  2017年   22篇
  2016年   30篇
  2015年   22篇
  2014年   29篇
  2013年   44篇
  2012年   45篇
  2011年   63篇
  2010年   45篇
  2009年   64篇
  2008年   62篇
  2007年   55篇
  2006年   45篇
  2005年   37篇
  2004年   32篇
  2003年   23篇
  2002年   26篇
  2001年   23篇
  2000年   21篇
  1999年   44篇
  1998年   117篇
  1997年   80篇
  1996年   40篇
  1995年   36篇
  1994年   28篇
  1993年   28篇
  1992年   13篇
  1991年   24篇
  1990年   21篇
  1989年   13篇
  1988年   24篇
  1987年   13篇
  1986年   12篇
  1985年   15篇
  1984年   9篇
  1983年   9篇
  1982年   8篇
  1981年   12篇
  1980年   6篇
  1979年   6篇
  1978年   8篇
  1977年   7篇
  1976年   14篇
  1975年   3篇
  1972年   4篇
排序方式: 共有1397条查询结果,搜索用时 31 毫秒
91.
Characteristics of a pulse corona reactor driven by an inductive energy storage (IES) pulsed power generator are described in this paper with focusing on the influence of streamer-to-glow transition on NO removal efficiency. A pulsed high voltage with a short rise time of under 30 ns is employed to generate streamer discharges homogeneously in whole the discharge region. Fast recovery diodes are used as semiconductor opening switch (SOS) to shorten the rise time. The various resistors are employed as dummy load to clarify a suitable circuit parameter such as the capacitance of a primary energy storage capacitor and/or the inductance of a secondary energy storage inductor. The energy transfer efficiency of the pulsed power generator has a maximum value of 50% at 714 Omega dummy load resistance. A co-axial cylinder type discharge chamber was used as the corona discharge plasma reactor driven by the IES pulsed power generator. The pulsed power generator supplies 30 kV pulse with 300 pps repetition rate. The co-axial cylinder plasma reactor consists of 1 mm diameter tungsten wire and 19 mm i.d. copper tube with 30 cm length. NO removal from the simulated diesel engine exhaust gas (N2:O2=9:1, Initial NO concentration=200 ppm) increased with input energy into the reactor. The energy efficiency for NO removal was obtained to be 25 g/kWh at 30 % removal in gas flow rate of 2 L/min. However, the energy efficiency decreased to 5 g/kWh with increasing capacitance of the primary capacitor from several hundreds pF to several nF. This decrease was caused by a streamer-to-glow transition. The efficiency was affected by oxygen concentration in the gas mixture.  相似文献   
92.
Transformable multi-links aerial robots have great potentials in application relying on the transformable features to change its shape during the flight. Compared to traditional quadrotor robots, transformable multi-links robots are equipped with servo motor between links. To simplify the non-linear dynamic system, the previous work restricts the robot to transform in very slow speed so that the robot could be approximated as a quadrotor robot at each time point. However, tradeoff comes as the dynamic performance is given up. In this paper, we come up with a new framework combining of computationally efficient non-linear model predictive controller and motion primitive to optimize thrust force and joints trajectory of the multi-links aerial robot. Finally, we verify our framework with fast transformation motions and table tennis task which requires dynamic performance.  相似文献   
93.
In this study, the potential of wood-only (metal-free) load-bearing walls was proposed and tested based on the idea of using the same type of material throughout wherever possible while improving basic properties such as strength, sound insulation, and heat insulation. Specifically, a technique was tested of combining pressure sensitive adhesive tape and wood dowels in place of nails for load-bearing structures with panel reinforcement represented by wood-frame construction. For this paper, its strength was evaluated by conducting in-plane shear tests, which revealed that the initial rigidity and maximum load of the proposed test specimens were greater than that of specimens using nails for jointing. However, the shear load factor, which is calculated based on some strength parameters and which forms the foundation of housing strength design, was slightly lower than that of the nail-jointed specimen. This was because there was a large decline in post-collapse resistance and a lower calculated absorbed energy caused by brittleness. The early detachment of panels was also revealed as a problem in the tests.  相似文献   
94.
Abstract— A novel reflective color LCD without polarizers has been developed using a PDLC film and a retro‐reflector. Bright color images including moving images are achievable with ambient light. This novel LCD will enable the new application area of electronic paper.  相似文献   
95.
For fast deposition of microcrystalline silicon (μc-Si:H) films, a microwave-induced high-density plasma source is developed. By using this plasma source, highly crystallized μc-Si:H films can be deposited from SiH4+He plasma without even using H2 dilution and substrate heating. A systematic deposition study shows that the film deposition rate increases with increase in the input microwave power and the SiH4 flow rate. The film crystallinity also improves with power but degrades with increase in the SiH4 flux. After optimizing the plasma conditions, the deposition of a highly crystallized μc-Si film has been realized at an ultrafast deposition rate higher than 700 nm/s.  相似文献   
96.
97.
Characteristics of fast pulse propagation in a large planar spark counter (PSC) are simulated using a pulser located inside the spark gap. Besides the main mode of pulse propagation, three undesirable modes are observed. These latter strongly distort the shape of the pulse. Characteristics of these modes and methods to eliminate their effects are demonstrated. We present an electrical design for a 120 cm spark counter along with some of its electrical properties as revealed by measurements made with the inner spark pulser. In the present counter design the charge of a pulse is shared by several neighboring strips, enabling one to measure the transverse position of a spark to a high degree of accuracy.  相似文献   
98.
Crystal structure, and electrical conducting and magnetic properties of a radical cation salt of EDO-TTFVODS with magnetic FeCl4? ion, (EDO-TTFVODS)2FeCl4 (EDO-TTFVODS = ethylenedioxytetrathiafulvalenoquinone-1,3-diselenolemethide) are reported. In this salt, there are two independent donor molecules formed two different layers A and B, and the counter FeCl4? ions layer is sandwiched between two donor layers A and B along the b-axis. The donor molecules form the one-dimensional columns along the a-axis in both donor layers. This salt shows high conductivity at room temperature (σRT = 25 S cm?1) and a metallic behavior down to ca. 80 K, where a metal–insulator transition however occurs. The magnetic susceptibility obeys a Curie–Weiss law (Curie constant C = 4.42 emu K mol?1 and Weiss temperature Θ = ?1.5 K), without any magnetic ordering down to 1.8 K. This result suggests the weak antiferromagnetic interaction between the d spins of FeCl4? ions.  相似文献   
99.
Cooking up an interactive olfactory game display.   总被引:2,自引:0,他引:2  
It's long been possible to give users outside an actual environment that environment's visual and auditory information and thus contribute to establishing presence. However, we've yet to establish much presence when users require olfactory information - such as in environments focused on foods, flowers, perfumes, or, in some cases, more offensive smells. Recently, several VR researchers have become interested in olfaction and olfactory displays that present smells in virtual environments (VEs). In this article, we describe our interactive olfactory display. One of our development goals is to confirm the assumption that users' interactions with the system increases presence. Thus, we used our interactive olfactory display to develop a cooking game in collaboration with electronic engineers and artists.  相似文献   
100.
A novel 1.3?m InGaAsP/lnP distributed-feedback buried-heterostructure laser diode on p-type InP substrate has been developed utilising a dopant diffusion technique. The laser has achieved a threshold current as low as 20 mA and high output power of 32 mW under CW and SLM operation.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号