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171.
本文研究了两种方式载荷循环(矩形波和锯齿波)对定向凝固镍基高温合金DZ176G高温蠕变行为的影响。结果表明,与恒载荷静态蠕变相比,载荷循环并不影响蠕变塑性,但降低了蠕变寿命,蠕变寿命的降低程序近拟与载荷循环粢九成正比,且矩形载荷循环比锯齿波载荷循环效果更为明显。提出载荷循环导致蠕变寿命的降低与载荷变化引起的滞弹性效应无关,而是蠕变变形加速的结果。在载荷降低时,蠕变阻力的松弛导致在随后加载期间,试样 相似文献
172.
H.J. Chen) H. Wever) ) Open Lab of State Education Commission of P.R. China for High Temperature Materials High Temperature Tests Shanghai Jiao Tong University Shanghai China) Institute of Metal Research TU Berlin Hardenb 《金属学报(英文版)》1999,(1)
1IntroductionTheinteractionbetweencreepandfatiguecanbeoccuredifthematerialisundercreepfatigueloading.Thecreepdeformationusu... 相似文献
173.
This paper aims to expand the application scope of bentonite. The structure of bentonite and the purification and pretreatment methods performed before its modification were reviewed. The modification of bentonite and its application in antibacterial materials were emphasized. 相似文献
174.
Erol Era Reat Apak 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1997,70(3):241-246
Turkish red mud (bauxite waste) has been mixed with dolomite and coke, pelletized and sintered at 1100°C, and finally smelted at 1550°C to produce pig iron and a slag. The slag was leached with 30% H2SO4 at 90°C. The leachate was diluted, ferric iron was reduced with SO2, and extracted with 5% D2EHPA solution in kerosene. Silica and Al2O3 were recovered from the remaining aqueous solution, while the organic extract was stripped with 10% Na2CO3 solution, finally hydrolysed and calcined to produce pigment-grade TiO2. The titanium recovery efficiency on the basis of slag weight was 84·7%. The extractive separation of titanium from both valencies of iron was investigated as a function of pH and time. A stoichiometric flowsheet for the whole process has been developed. ©1997 SCI 相似文献
175.
音频记录磁带恢复技术在抢救文艺有声资料项目中的应用 总被引:1,自引:0,他引:1
中央人民广播电台"抢救文艺有声资料"项目实施小组 《广播与电视技术》2005,32(9):39-40
老化音频资料磁带有必要进行物理和化学方法的修复处理,以利在进行资料转储和重建时能采集到更好质量的信号.利用本项目技术处理后的录音资料磁带,其回放效果是向原录状态回归的,是本原的和原始状态的,处理过程中未加入任何用以改善放音音质的信号成分.相对于音频信号数字补偿方法,其输出结果具有更好的主观接受度和客观真实度. 相似文献
176.
Sundararajan N Mao D Chan S Koo TW Su X Sun L Zhang J Sung KB Yamakawa M Gafken PR Randolph T McLerran D Feng Z Berlin AA Roth MB 《Analytical chemistry》2006,78(11):3543-3550
Posttranslational modification (PTM) of proteins is likely to be the most common mechanism of altering the expression of genetic information. It is essential to characterize PTMs to establish a complete understanding of the activities of proteins. Here, we present a sensitive detection method using surface-enhanced Raman spectroscopy (SERS) that can detect PTMs from as little as zeptomoles of peptide. We demonstrate, using model peptides, the ability of SERS to detect a variety of protein modifications, such as acetylation, trimethylation, phosphorylation, and ubiquitination. In addition, we show the capability to obtain positional information for modifications such as trimethylation and phosphorylation using SERS and wavelet decomposition data analysis techniques. We further show that it is possible to apply SERS to detect PTMs from biological samples such as histones. We envision that this detection method might be a valuable technique that is complementary to mass spectrometry in obtaining orthogonal chemical and modification-specific information from biological samples at sensitive levels. 相似文献
177.
Effects of frequency-dependent attenuation and velocity dispersion on in vitro ultrasound velocity measurements in intact human femur specimens 总被引:1,自引:0,他引:1
Haïat G Padilla F Cleveland RO Laugier P 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2006,53(1):39-51
Numerous studies have shown that ultrasonic velocity measured in bone provides a good assessment of osteoporotic fracture risk. However, a lack of standardization of signal processing techniques used to compute the speed of sound (SOS) complicates the comparison between data obtained with different commercial devices. In this study, 38 intact femurs were tested using a through-transmission technique and SOS determined using different techniques. The resulting difference in measured SOS was determined as functions of the attenuation and the velocity dispersion. A numerical simulation was used to explain how attenuation and dispersion impact two different SOS measurements (group velocity, velocity based on the first zero crossing of the signal). A new method aimed at compensating for attenuation was devised and led to a significant reduction in the difference between SOS obtained with both signal processing techniques. A comparison between SOS and X-ray density measurements indicated that the best correlation was reached for SOS based on the first zero crossing apparently because it used a marker located in the early part of the signal and was less sensitive to multipath interference. The conclusion is that first zero crossing velocity may be preferred to group velocity for ultrasonic assessment at this potential fracture site. 相似文献
178.
179.
L. V. Maneeshya V. S. Anitha Sujatha S. Lekshmy I. John Berlin Prabitha B. Nair Georgi P. Daniel P. V. Thomas K. Joy 《Journal of Materials Science: Materials in Electronics》2013,24(3):848-854
Homogeneous and transparent BaTiO3 thin films were prepared by sol–gel dip coating method. The prepared BaTiO3 thin films were annealed in air and O2 atmosphere at different temperatures. The annealed BaTiO3 thin films were amorphous in nature. Scanning electron microscopy (SEM) revealed the nucleation and particle growth on the films. Energy-dispersive X-ray (EDX) analysis data revealed the adsorption of oxygen atoms in the BaTiO3 film. The direct energy band gap was found to vary (3.84–3.58 eV) as functions of annealing atmosphere and temperature. Photoluminescence (PL) revealed intense emission peaks at 393 and 675 nm. Quenching of PL intensity was observed in films annealed at high temperature and in O2 atmosphere. This is due to reduction in the oxygen vacancy by the adsorption of oxygen in the film. Luminescence spectra also have been related to the results obtained by SEM and EDX analysis. The change in luminescence intensity of BaTiO3 thin films makes it suitable for optoelectronic temperature sensor applications. 相似文献
180.
A. A. Konoplev G. G. Aleksanyan B. L. Rytov A. A. Berlin 《Theoretical Foundations of Chemical Engineering》2012,46(6):601-608
The effect of the open flow area of the intertubular channel on heat transfer parameters in the case of longitudinal flow past tubes is considered using tube-in-tube heat exchangers with smooth and profiled tubes as examples. It is demonstrated that the heat transfer efficiency can be enhanced by reducing the open flow area. By optimizing the tubular and intertubular spaces, it is possible to make the tubular heat exchanger much more compact. 相似文献