全文获取类型
收费全文 | 1055篇 |
免费 | 23篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 93篇 |
化学工业 | 207篇 |
金属工艺 | 31篇 |
机械仪表 | 18篇 |
建筑科学 | 9篇 |
能源动力 | 18篇 |
轻工业 | 48篇 |
无线电 | 109篇 |
一般工业技术 | 147篇 |
冶金工业 | 304篇 |
原子能技术 | 18篇 |
自动化技术 | 80篇 |
出版年
2022年 | 11篇 |
2021年 | 20篇 |
2020年 | 11篇 |
2019年 | 9篇 |
2018年 | 9篇 |
2017年 | 13篇 |
2016年 | 8篇 |
2015年 | 8篇 |
2014年 | 23篇 |
2013年 | 42篇 |
2012年 | 38篇 |
2011年 | 38篇 |
2010年 | 38篇 |
2009年 | 39篇 |
2008年 | 40篇 |
2007年 | 31篇 |
2006年 | 23篇 |
2005年 | 32篇 |
2004年 | 22篇 |
2003年 | 28篇 |
2002年 | 20篇 |
2001年 | 23篇 |
2000年 | 18篇 |
1999年 | 31篇 |
1998年 | 135篇 |
1997年 | 87篇 |
1996年 | 45篇 |
1995年 | 27篇 |
1994年 | 42篇 |
1993年 | 33篇 |
1992年 | 17篇 |
1991年 | 9篇 |
1990年 | 7篇 |
1989年 | 11篇 |
1988年 | 8篇 |
1987年 | 8篇 |
1986年 | 8篇 |
1985年 | 4篇 |
1984年 | 5篇 |
1983年 | 10篇 |
1982年 | 4篇 |
1981年 | 6篇 |
1980年 | 4篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1977年 | 5篇 |
1976年 | 10篇 |
1975年 | 4篇 |
1974年 | 3篇 |
1973年 | 4篇 |
排序方式: 共有1082条查询结果,搜索用时 15 毫秒
991.
Susumago I. Suzuki M. Miyama K. Tsuji T. Dan K. Yamanishi A. 《Power Systems, IEEE Transactions on》1986,1(2):67-73
The Tokyo Electric Power Co., Inc. (TEPCO) and Mitsubishi Electric Corp. developed a large-scale dispatcher training simulator ELDIS (Electric Load DIspatching Simulator) in February 198 after three years of joint research. This simulator can be used not only for training in normal operating activities, but also for training in the handling of emergency and restorative operations under abnormal conditions. The simulator has been installed at the Dispatcher Training Center in TEPCO where it has been used for four to five days a week for training of about 250 dispatchers in the Central, Area, and Local Load Dispatching Centers. It has contributed greatly to achieving reliable power system operations. This paper gives an overview of the ELDIS and describes the training course, the simulator functions, and the training results. 相似文献
992.
We determined whether Arg13, Met31, and Ser95 of the heat-labile enterotoxin B subunit (LT-B) might be involved in Lt-B binding to oligosaccharides, which did not bind to the B subunit of the cholera toxin (CT-B). Three LT-B mutants, R13H, M31L, and S95A were prepared by substituting three amino acid residues that differ in CT-B. These mutants formed a pentamer and exhibited the same binding ability to the GM1 ganglioside as native LT-B. Although these mutants did not bind to Bio-Gel A-5m, they did bind to the glycoprotein from mouse intestinal cells in the order R13H > M31L > S95A. These data suggest that Ser95, Met31, and Arg13 are important for LT-B binding to Bio-Gel A-5m, and that although Ser95 is also partially responsible for LT-B binding to the glycoprotein, Arg13 has no significant involvement in it. 相似文献
993.
994.
This paper presents a pattern discrimination method for electromyogram (EMG) signals for application in the field of prosthetic control. The method uses a novel recurrent neural network based on the hidden Markov model. This network includes recurrent connections, which enable modeling time series, such as EMG signals. Weight coefficients in the network can be learned using a well-known back-propagation through time algorithm. Pattern discrimination experiments were conducted to demonstrate the feasibility and performance of the proposed method. We were able to successfully discriminate forearm motions using the EMG signals, and achieved considerably high discrimination performance compared with other discrimination methods. 相似文献
995.
Masahiro Tabata Kazuhiro Akanuma Ken'ichi Nishizawa Keisuke Mimori Takashi Yoshida Masamichi Tsuji Yutaka Tamaura 《Journal of Materials Science》1993,28(24):6753-6760
The reduction of CO2 to carbon was studied in oxygen-deficient Mn(II)-bearing ferrites (Mn
x
Fe3-x
O4-, Ox1, >0) at 300 °C. They were prepared by reducing Mn(II)-bearing ferrites with H2 gas at 300°C. The oxygen-deficient Mn(II)-bearing ferrites showed a single phase with a spinel structure having an oxygen deficiency. The decomposition reaction of CO2 to carbon was accompanied by oxidation of the oxygen-deficient Mn(II)-bearing ferrites. The decomposition rate slowed when the Mn(II) content in the Mn(II)-bearing ferrites increased. A Mössbauer study of the phase changes of the solid samples during the H2 reduction and CO2 decomposition indicated the following. Increases in the Mn(II) content lowered the electron conductivity of the Mn(II)-bearing ferrites. Increases in the oxygen deficiency, , contributed to an increase in electron conductivity and suggested that electron conduction due to the electron hopping determines the reductivity of CO2 to carbon by the donation of an electron at adsorption sites. 相似文献
996.
The gas chromatographic analysis of various kinds of nonionic surfactants has been carried out after chemical decomposition
using the mixed anhydride of acetic and p-toluene sulfonic acids which acts as a reagent for cleavage of ether linkages. The
gas chromatographic peaks of the reaction products show the alkyl distributions of the hydrophobic groups of ethylene oxide
adducts. The alkyl compositions closely agree with those of the starting materials. In this way, the hydrophobic groups of
polyoxyethylene alkyl ether, polyoxyethylene alkyl phenol ether, polyoxyethylene alkyl amine, and polyoxyethylene alkyl thioether
have been analyzed. At the same time, the hydrophilic group, namely polyoxyethylene group, can be identified in the form of
ethylene glycol diacetate. 相似文献
997.
Poly(?‐caprolactone) (PCL) and poly[(R)‐3‐hydroxybutyrate] (R‐PHB) films with pores and hydrophilic surfaces were prepared by the water extraction of poly(ethylene oxide) from as‐cast blend films (1:1) and by the alkali treatment of as‐cast nonporous films, respectively. These films, as well as as‐cast nonporous PCL and R‐PHB films, were biodegraded in static seawater kept at 25°C, and their biodegradation was monitored with gravimetry, gel permeation chromatography (GPC), and scanning electron microscopy. The pores or highly hydrophilic surfaces of the PCL and R‐PHB films enhanced their biodegradation in seawater. Moreover, GPC measurements could be used to trace the biodegradation in seawater when the biodegradation proceeded to a great extent. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 587–593, 2003 相似文献
998.
Binary blend films from lactide-rich poly(D -lactide-co-glycolide) (PDLG) and poly(L -lactide-co-glycolide) (PLLG) were obtained by casting methylene chloride solutions of the two mixed copolymers with different D- and L-lactide contents (XDI and XLI ), and their crystallization was studied by differential scanning calorimetry (DSC). Four combinations were selected from the binary (A-B) blends: mixing of the same polymer [XDI (A) = XDI (B) or XLI (A) = XLI(B)], blending under XDI (B) = XLI (A), blending of a D -lactide homopolymer [XDI(B) = 1] with other PDLGs, and blending of a D -lactide homopolymer [XDI(B) = 1] with other PLLGs. Racemic crystallites were exclusively formed between PDLG and PLLG when they had high lactide unit contents. The melting point and enthalpy of fusion of the racemic crystallites decreased with a decrease in XDI of PDLG or XLI of PLLG, suggesting that glycolide units in the polymer disturbed the growth of the racemic crystallites. A similar behavior was also observed for the homocrystallization in nonblended copolymer films. Homocrystallites composed entirely either of D -lactide unit or L-lactide unit sequences were formed when one component was crystallizable and the other component had the same sign of optical rotation or very different lactide content. An interesting finding was that even nonhomocrystallizable lactide-poor PDLG and PLLG could form racemic crystallites when both were blended. © 1994 John Wiley & Sons, Inc. 相似文献
999.
With regard to Ni-50Ti-Cu (at%) shape memory alloys, phase transformation characteristics under no stress were studied at the copper content of 6–9 at% using differential scanning calorimetry and X-ray diffraction analysis. In solution-treated materials, B2-orthorhombic transformation occurs at the copper content of 7.6 at% or more. With the increase in copper content, the temperature for B2-orthorhombic transformation gradually increases, whereas the temperature for the orthorhombic-monoclinic phase transformation resulting from decreasing temperature rapidly falls. The phase transformation temperature in 27% cold-worked materials remains virtually constant, despite the copper content, and increases with increasing heat-treatment temperature. The hysteresis in the B2-orthorhombic transformation stabilized via cold working is as low as 18 K. 相似文献
1000.
A novel bi-directionally fed phased-array antenna (BiPA) is presented. A BiPA can operate at half the phase shift of the conventional antenna with the same performance, leading to smaller size and lower cost. Main components of a BiPA are antenna elements and variable impedance phase shifters (VIPSs). The VIPS consists of three resonant circuits that include variable capacitors, it is applicable for both functions as a power divider and as an impedance-matching device, since the input/output impedance and the phase shift can be independently varied. The BiPA with a VIPS is simulated and evaluated at a 2.45-GHz industrial-scientific-medical band. The measured results agree well with the simulated ones. The performances of the VIPSs are confirmed as 1.4 dB in insertion loss, and -17dB in return loss for a phase shift of 0/spl sim/80/spl deg/ with the control voltage from 0- to 3.5-V DC, and the measured radiation pattern of the BiPA is /spl plusmn/30/spl deg/ in the steering angle, 24/spl deg/ in beamwidth, and -9dB in the sidelobe. Furthermore, an enhancement of the sidelobe suppression can be expected by changing the power ratio of each antenna element. 相似文献