全文获取类型
收费全文 | 407篇 |
免费 | 9篇 |
专业分类
电工技术 | 7篇 |
化学工业 | 40篇 |
金属工艺 | 6篇 |
机械仪表 | 19篇 |
建筑科学 | 6篇 |
能源动力 | 21篇 |
轻工业 | 10篇 |
无线电 | 113篇 |
一般工业技术 | 63篇 |
冶金工业 | 48篇 |
原子能技术 | 3篇 |
自动化技术 | 80篇 |
出版年
2023年 | 1篇 |
2022年 | 4篇 |
2021年 | 6篇 |
2020年 | 2篇 |
2019年 | 2篇 |
2018年 | 3篇 |
2017年 | 5篇 |
2016年 | 4篇 |
2015年 | 6篇 |
2014年 | 10篇 |
2013年 | 16篇 |
2012年 | 11篇 |
2011年 | 24篇 |
2010年 | 24篇 |
2009年 | 25篇 |
2008年 | 30篇 |
2007年 | 27篇 |
2006年 | 13篇 |
2005年 | 18篇 |
2004年 | 7篇 |
2003年 | 9篇 |
2002年 | 11篇 |
2001年 | 8篇 |
2000年 | 10篇 |
1999年 | 7篇 |
1998年 | 16篇 |
1997年 | 19篇 |
1996年 | 11篇 |
1995年 | 8篇 |
1994年 | 9篇 |
1993年 | 8篇 |
1992年 | 6篇 |
1991年 | 7篇 |
1990年 | 6篇 |
1989年 | 9篇 |
1988年 | 9篇 |
1987年 | 3篇 |
1986年 | 4篇 |
1985年 | 3篇 |
1984年 | 1篇 |
1983年 | 3篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 2篇 |
排序方式: 共有416条查询结果,搜索用时 140 毫秒
31.
Chi-ming Lai Hung-Chi Su Ming-Ju Tsai Chien-Jung Chen Chun-Ta Tzeng Ta-Hui Lin 《Building and Environment》2010
An experiment is conducted on a full-scale model office and an actual sprinkler system to explore the influence of fire source locations on sprinkler actuation. The office space is a brick structure that measures 5.7 m in interior length, 4.7 m in width and 2.4 m in ceiling height, and equipped with a sprinkler system. The investigated fire source (100 kW LPG burner) locations include the room center, wall centers, room corner, and other locations at different distances from sprinklers. The results show that actuation of the sprinklers is affected by the fire source locations and the heat conduction properties of the glass temperature-sensing bulb. Average actuation time of all the tests is 102 s, around 40 s faster than if the fire source is located in the room center. For fire sources in corners, sprinklers are quickly activated at the experimental time 75 s, showing concentrated hot gas flow. 相似文献
32.
Sung Kee Kim Mizuhara O. Park Y.K. Tzeng L.D. Kim Y.S. Jichai Jeong 《Lightwave Technology, Journal of》1999,17(8):1320-1325
This paper has experimentally and theoretically investigated transmission performance depending on chirping and extinction ratio for a 10 Gb/s transmission system with the standard single-mode fiber. The transmission performance can be dramatically degraded or improved by adjusting chirp and extinction ratio in a 1.55 μm LiNbO3 modulator-based transmitter and erbium-doped fiber amplifier (EDFA)-pin diode receiver configuration. To estimate the transmission performance, bit error rate (BER) characteristics rather than eye-opening penalty (EOP) have been calculated by solving the nonlinear Schrodinger equation with including the model of chirping and extinction ratio for the transmitter, and noise and intersymbol interference for the receiver. This simulation can predict the measured BER characteristics well enough to see interplaying between chirping and extinction ratio 相似文献
33.
Shinn-Shyong Tzeng Yang-Li Fang Ya-Ko Chih Yi-Ching Lin Chin-Fen Tuan 《Diamond and Related Materials》2010,19(7-9):783-786
DLC films were synthesized by RF plasma enhanced chemical vapor deposition and the effects of nitrogen plasma post-treatment at different pressures on the structure and properties of DLC films were investigated. Higher roughness was obtained after plasma post-treatment at higher pressures (0.3 and 0.9 torr) and plasma post-treatment at a lower pressure (0.15 torr) resulted in lower roughness than that of original films. The hardness of DLC films decreased with the decrease of post-treatment pressure, which is consistent with the Raman results of ID/IG ratio and G peak position. Compared to the original DLC film, the residual stress after plasma post-treatment decreased slightly due to the relatively thin region involved in the plasma post-treatment. 相似文献
34.
Zong-Hao Ye Kuei-Shu Chang-Liao Te-Chiang Liu Tien-Ko Wang Pei-Jer Tzeng Cha-Hsin Lin Min-Jinn Tsai 《Microelectronic Engineering》2009,86(7-9):1863-1865
Although enhancement in electrical properties of flash devices with HfO2 charge trapping layer has been reported, there are serious problems in retention characteristics. In this work, a novel SONOS-type flash device with TaN/Al2O3/HfO2/Si3N4/SiO2/Si structure is presented. Experimental results show that the program/erase speeds of the proposed devices can be enhanced by over one thousand times and the retention characteristic is improved as well. 相似文献
35.
C.-P. Tzeng Hodges D. Messerschmitt D. 《Selected Areas in Communications, IEEE Journal on》1986,4(8):1302-1311
Sampled-data techniques are the most practical means of obtaining the necessary signal processing functions for timing recovery in the VLSI implementation of a digital subscriber loop transceiver. The sampled-data timing recovery techniques described in this paper are applicable to both echo cancellation and time-compression multiplexing systems. Timing recovery using baud-rate sampling in conjunction with a special pulse-shaping and timing function fulfills all the objectives for timing recovery in this application. It recovers a timing phase that has minimum precursor intersymbol interference, and makes possible the combination of decision feedback equalizer and echo canceler, reducing the convergence time and increasing the step size. The pulse-shaping function can be performed either in the transmitter by means of digital coding, or in the receiver by means of analog filtering. In the latter case, the transmitted pulse is compatible with more conventional approaches. The proposed partial-response line coding, a special form of AMI coding, is less susceptible to line impairments if detected as a two-level signal. Performance by analysis, simulation, and experimental measurements is reported on a variety of cable configurations, some including bridged taps. Analysis of jitter performance leads to design techniques for reducing the jitter magnitude. 相似文献
36.
Chwen-Jeng Tzeng Reza Iranpour Michael K. Stenstrom 《Canadian Metallurgical Quarterly》2003,129(5):402-411
A dynamic mathematical model for the high purity oxygen activated sludge process, which incorporates structured biomass, gas–liquid interactions and control systems, was developed. The model was calibrated using pilot plant data associated with the development of the West Point Treatment Plant near Seattle, Wash. The calibrated model was used to simulate oxygen transfer rates for various operating conditions. Simulations showed that an optimal control system can reduce aerator power by 33% as compared to a conventional design, and reduce average oxygen feed gas by as much as 18%. Vent gas purity control dramatically reduced the peak aerator horsepower required to maintain set point dissolved oxygen concentration during high loadings. Step feed operation reduced the stag-to-stage variation in aerator horsepower and also reduced the required peak power. Predicted power savings for a 605,000?m3/day plant were $500,000 per year at current power costs. 相似文献
37.
Dinoseb is a herbicide known to inhibit photosystem II electron transfer like DCMU, triazine and phenolic-type herbicides. The mutant Din7 of the cyanobacterium Synechocystis sp. PCC 6803, selected for resistance to dinoseb, and the mutant Ins2, constructed by the insertion of the kanamycin resistance cassette into the drgA gene, were cross-resistant to other nitrophenolic herbicides (DNOC, 2,4-dinitrophenol) and to the cell inhibitor metronidazole but not to the photosystem II inhibitors DCMU or ioxynil. The Din7 mutant had the same characteristics of photosystem II inhibition by dinoseb as the wild type. This result suggested the existence of another site for dinoseb inhibition. The wild type cells modified dinoseb to a non-toxic product that gave an absorption spectrum similar to that of dithionite treated dinoseb containing reduced nitro groups. In contrast, the Din7 mutant did not modify dinoseb. These phenomena were controlled by the drgA gene encoding a protein which showed similarity to several enzymes having nitroreductase activity. The addition of superoxide dismutase to the medium relieved the toxic effect of dinoseb in wild type cells but not in Din7. It is proposed that in wild type cells of Synechocystis sp. PCC 6803 the DrgA protein is involved in detoxification of dinoseb via the reduction of the nitro group(s) and this process is accompanied by the formation of toxic superoxide anions. Mutations blocking the activity of the DrgA protein lead to the development of resistance to nitrophenolic herbicides and metronidazole. 相似文献
38.
Field-dependence of the area-density of 'cold' electron emission sites on broad-area CVD diamond films 总被引:3,自引:0,他引:3
A high area density of field-induced electron emission sites has been observed on broad-area (12 mm in diameter) CVD diamond films deposited on molybdenum substrates. Furthermore, it was found that the density increased with the electric field applied to the surface of the films. These findings indicate that the CVD diamond film has to be seen as a potentially favoured candidate among electronic materials for the development of new types of cold cathode electron source.<> 相似文献
39.
In the ATM Forum activities, considerable efforts have focused on the congestion control of point-to-point available bit rate (ABR) service. We present a novel approach that extends existing point-to-point (unicast) congestion control protocols to a point-to-multipoint (multicast) environment. In particular, we establish a unified framework to derive a multicast congestion control protocol for an ABR service from a given rate-based unicast protocol. We generalize a known necessary and sufficient condition on the max-min fairness of unicast rate allocation for a multicast service. Using this condition, we show that the resulting multicast protocol derived using our framework preserves the fairness characteristics of the underlying unicast protocol. The practical significance of our approach is illustrated by extending a standard congestion control mechanism for an ABR service to a multicast environment. The performance of the resulting multicast protocol is examined using benchmark network configurations suggested by the traffic management subworking group at the ATM Forum, and simulation results are presented to substantiate our claims 相似文献
40.
Po-Lun Chen Kuen-Cherng Lin Wei-Ching Chuang Yen-Chang Tzeng Kun-Yi Lee Wei-Yu Lee 《Photonics Technology Letters, IEEE》1997,9(4):467-469
The authors propose a novel analysis method to investigate the characteristics of an electrically tunable liquid-crystal Fabry-Perot interferometer (LC-FPI). Based on the solution of deformation analysis of the liquid crystal in an electric field and the assumption of small refractive index variation in the Fabry-Perot cavity, the voltage-dependent equivalent refractive index of the cavity has been derived. Tuning behaviors of the LC-FPI filter were simulated by means of the dependence. The calculated result and the experimental measured data agree well with each other. 相似文献