全文获取类型
收费全文 | 1198篇 |
免费 | 26篇 |
国内免费 | 6篇 |
专业分类
电工技术 | 112篇 |
综合类 | 2篇 |
化学工业 | 408篇 |
金属工艺 | 25篇 |
机械仪表 | 28篇 |
建筑科学 | 30篇 |
能源动力 | 64篇 |
轻工业 | 110篇 |
水利工程 | 1篇 |
无线电 | 66篇 |
一般工业技术 | 230篇 |
冶金工业 | 40篇 |
原子能技术 | 30篇 |
自动化技术 | 84篇 |
出版年
2023年 | 9篇 |
2022年 | 7篇 |
2021年 | 19篇 |
2020年 | 7篇 |
2019年 | 9篇 |
2018年 | 19篇 |
2017年 | 17篇 |
2016年 | 22篇 |
2015年 | 12篇 |
2014年 | 19篇 |
2013年 | 61篇 |
2012年 | 39篇 |
2011年 | 47篇 |
2010年 | 44篇 |
2009年 | 72篇 |
2008年 | 50篇 |
2007年 | 69篇 |
2006年 | 56篇 |
2005年 | 57篇 |
2004年 | 58篇 |
2003年 | 46篇 |
2002年 | 39篇 |
2001年 | 36篇 |
2000年 | 41篇 |
1999年 | 24篇 |
1998年 | 31篇 |
1997年 | 27篇 |
1996年 | 24篇 |
1995年 | 23篇 |
1994年 | 14篇 |
1993年 | 16篇 |
1992年 | 15篇 |
1991年 | 18篇 |
1990年 | 9篇 |
1989年 | 16篇 |
1988年 | 12篇 |
1987年 | 16篇 |
1986年 | 20篇 |
1985年 | 20篇 |
1984年 | 11篇 |
1983年 | 13篇 |
1982年 | 10篇 |
1981年 | 6篇 |
1980年 | 6篇 |
1979年 | 13篇 |
1977年 | 7篇 |
1976年 | 5篇 |
1975年 | 3篇 |
1974年 | 3篇 |
1973年 | 3篇 |
排序方式: 共有1230条查询结果,搜索用时 15 毫秒
61.
Many compounds that taste bitter to humans also inhibit feeding in insects. Caterpillars (e.g., Manduca sexta) detect these compounds with a few bitter-sensitive taste cells. This study examined the role of these taste cells in feeding inhibition. Behavioral studies demonstrated that 3 bitter compounds (caffeine, salicin, and aristolochic acid) all inhibited feeding rapidly in Manduca sena. Electrophysiological studies revealed that each pair of bitter-sensitive taste cell differs in responsiveness to the bitter compounds. Ablation studies indicated that (a) those pairs of bitter-sensitive taste cells that responded vigorously to a particular bitter compound were sufficient to inhibit feeding on diets containing the same compound, but that (b) no pair of bitter-sensitive taste cells was necessary for inhibiting feeding. Thus, the different pairs of bitter-sensitive taste cells appear to make partially redundant contributions to feeding inhibition. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
62.
A molecular structure viewer program, MOSBY has been developed for studies that use atomic coordinates to understand the structures of protein molecules. The program is designed to be portable with a comprehensive user interface by our high-throughput graphics library. In addition, it cooperates with extension modules customized for individual research topics and analysis. For example, an electron density module loads and displays electron density maps derived in X-ray crystallographic analysis superimposed to an atomic model. A molecular dynamics module reads a trajectory file of the results of molecular dynamics calculations and animates the structure. These plug-in modules are devised to function without modification to the MOSBY program. For variations of analysis and calculations with atomic coordinates, the portability and extensibility illustrated by MOSBY play an important rule in scientific computational tools with active software development. 相似文献
63.
Honda Y Kitaoka M Sakka K Ohmiya K Hayashi K 《Journal of Bioscience and Bioengineering》2002,93(3):313-317
The kinetic parameters of Cex, a family 10 xylanase from Cellulomonas fimi, were determined at various pH levels using soluble birchwood xylan (BWX) as a natural polymeric substrate along with three other synthetic aryl-beta-D-xylobioside substrates. Using BWX, a high level of substrate inhibition was observed which increased with decreasing pH. In contrast, typical Michaelis-Menten-type profiles were obtained using the three aryl-beta-D-xylobiosides as substrates. The k(cat) values determined using o-nitrophenyl-beta-D-xylobioside did not change as the pH increased, whereas the k(cat) values obtained with BWX, phenyl-beta-D-xylobioside and p-nitrophenyl-beta-D-xylobioside decreased, suggesting that the presence of an ortho nitro group affects the activity displayed by Cex. These differences were not observed with XynB from Clostridium stercorarium F9, a member of the same family of xylanases as Cex. These results indicate that a careful evaluation is required when employing substituted aryl-beta-D-xylobiosides in the characterization of xylanases. 相似文献
64.
65.
Keisuke Hachisuka Teruhito Takeda Yusuke Terauchi Ken Sasaki Hiroshi Hosaka Kiyoshi Itao 《Microsystem Technologies》2005,11(8-10):1020-1027
Intra-body communication is a wireless means of exchanging information within a personal area network (PAN) between wearable electronic sensors and devices. The feasibility of intra-body communication is confirmed through several experiments on signal propagation within the human body, and a human phantom is designed and used to obtain reproducible results over repeated experiments. Based on the results of these experiments, a prototype transmission system is constructed using aluminum electrodes powered by 3 V DC and operating in the 10.7 MHz frequency modulation (FM) band. This prototype is demonstrated to be capable of transmitting analog signals through the human subjects in the presence of external noise. Digital data transmission at 9600 bps is also achieved using newly fabricated 10.7 MHz frequency shift keying (FSK) transmitter and receiver devices. The carrier frequency of 10.7 MHz is the intermediate frequency of FM radio receivers, meaning that the proposed system can make use of a wide selection of inexpensive, commercial radio frequency devices. 相似文献
66.
Makoto Ishii Kenji Saito Tomokazu Shiga Kiyoshi Igarashi Shigeo Mikoshiba Jooyul Lee Kyoung Ho Kang Heehwan Kim Changbae Park 《Journal of the Society for Information Display》2002,10(1):5-10
A hybrid AWD/AND drive technique has been developed in which an Address‐While‐Display (AWD) scheme is combined with an AND logic characteristic that gas discharges demonstrate. The AWD technique enables AC‐PDPs to be driven at high luminance, while the AND logic reduces the number of scan drivers by an order of magnitude. A detailed analysis of the addressing operation has been made. The hybrid drive utilizes the AND logic in two ways: (1) a combination of two voltage pulses and (2) a combination of a voltage pulse and discharge‐priming particles. It was found that the addressing operation requires the establishment of a discharge between the scan and data electrodes, and also between the scan and display electrodes. 相似文献
67.
Ryosuke Ueyama Masahiro Harada Tamotu Ueyama Takashi Yamamoto Tadashi Shiosaki Kiyoshi Kuribayashi Kunihito Koumoto Won Son Seo 《Journal of Materials Science: Materials in Electronics》2000,11(2):139-143
Ultrafine BaTiO3 particles were prepared by a micro-emulsion charring (MEC) method. The MEC method consisted of two steps. The first step is the preparation of a water/oil micro-emulsion with BaTiO3 elements, and the second is a low temperature firing process in N2 atmosphere, which includes charring of oil in an emulsion and powdering BaTiO3 particles with the char. The char formed around BaTiO3 particles prevents an agglomeration of BaTiO3 particles during firing. In the present experiment, the W/O ratio and the amount of emulsifier greatly influenced the size of droplets of the emulsion. The charring temperature was another important experimental factor in order to obtain the desired BaTiO3 particles. The finally obtained BaTiO3 charring powders were monodispersed spherical particles and the particle size was 0.1 m to 0.5 m. 相似文献
68.
69.
We propose a synthesis method of optical Hadamard transformer using multimode interference (MMI) couplers. By using the signal transfer matrix of 2 x 2, 4 x 4, and 8 x 8 MMI couplers, we show that sum and difference units of input signals can be synthesized. An interchange unit of two signals can also be synthesized. One synthesis method of Hadamard transformers is a combination of only 2 x 2 units, and the other is a combination of N x N(N > or = 4) units as well as 2 x 2 units. The design examples of operation units are shown, and the size and the output power of Hadamard transformers are estimated. 相似文献
70.
A novel adaptive backstepping design for a class of nonlinearly parameterized systems with a triangular structure is proposed. Under the Lipschitz condition with respect to unknown parameters of the system, an effective adaptive controller is designed without the requirement on the compactness of the unknown parametric set. Especially, the proposed adaptive control enables the advantage of “tuning function concept”, which results in only one estimation law for the unknown parameters. Our simulation with induction motor model particularly shows the viability of the obtained results. 相似文献