全文获取类型
收费全文 | 600篇 |
免费 | 37篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 8篇 |
化学工业 | 143篇 |
金属工艺 | 31篇 |
机械仪表 | 28篇 |
建筑科学 | 18篇 |
矿业工程 | 3篇 |
能源动力 | 21篇 |
轻工业 | 118篇 |
水利工程 | 1篇 |
石油天然气 | 3篇 |
无线电 | 22篇 |
一般工业技术 | 143篇 |
冶金工业 | 6篇 |
原子能技术 | 5篇 |
自动化技术 | 90篇 |
出版年
2023年 | 3篇 |
2022年 | 4篇 |
2021年 | 17篇 |
2020年 | 15篇 |
2019年 | 16篇 |
2018年 | 26篇 |
2017年 | 13篇 |
2016年 | 26篇 |
2015年 | 25篇 |
2014年 | 43篇 |
2013年 | 97篇 |
2012年 | 38篇 |
2011年 | 30篇 |
2010年 | 51篇 |
2009年 | 43篇 |
2008年 | 35篇 |
2007年 | 17篇 |
2006年 | 9篇 |
2005年 | 4篇 |
2004年 | 4篇 |
2003年 | 5篇 |
2002年 | 7篇 |
2000年 | 3篇 |
1999年 | 5篇 |
1998年 | 6篇 |
1997年 | 5篇 |
1996年 | 9篇 |
1995年 | 5篇 |
1994年 | 4篇 |
1993年 | 2篇 |
1992年 | 4篇 |
1989年 | 2篇 |
1988年 | 3篇 |
1986年 | 4篇 |
1985年 | 3篇 |
1984年 | 8篇 |
1982年 | 2篇 |
1981年 | 4篇 |
1980年 | 3篇 |
1978年 | 4篇 |
1977年 | 3篇 |
1976年 | 4篇 |
1975年 | 2篇 |
1974年 | 3篇 |
1973年 | 3篇 |
1972年 | 3篇 |
1970年 | 2篇 |
1962年 | 2篇 |
1961年 | 3篇 |
1957年 | 2篇 |
排序方式: 共有640条查询结果,搜索用时 0 毫秒
101.
Jaroslav Černý 《Petroleum Science and Technology》2013,31(6):807-818
ABSTRACT Four bituminous coals were comprehensively separated by column chromatography into a number of fractions. Four aromatic hydrocarbon fractions of each tar were analyzed by FTIR spectroscopy, and the 900-700 cm?1 spectral region was evaluated. This spectral region was found to be composed of at least 14 separate bands, which were resolved by using self-deconvolution and curve-fitting procedures. The bands near 821 cm?1, 791 cm?1, and 784 cm?1 were proposed to originate from rocking vibrations of aliphatic C-H bonds. For the tar samples with a proton aromaticity between 0.21 and 0.37, these bands account for on average 12% of the total integral intensity of the 900-700 cm?1 region. This percentage cannot likely be neglected in a correct quantitative evaluation of the region and calculation of the aromatic hydrogen concentration. However, a correct resolution of the bands can be very difficult in the FTIR spectra of a complex material, such as coal. 相似文献
102.
E. MIKMEKOVÁ H. BOUYANFIF M. LEJEUNE I. MÜLLEROVÁ M. HOVORKA M. UNČOVSKÝ L. FRANK 《Journal of microscopy》2013,251(2):123-127
Commercially available graphene samples are examined by Raman spectroscopy and very low energy scanning transmission electron microscopy. Limited lateral resolution of Raman spectroscopy may produce a Raman spectrum corresponding to a single graphene layer even for flakes that can be identified by very low energy electron microscopy as an aggregate of smaller flakes of various thicknesses. In addition to diagnostics of graphene samples at larger dimensions, their electron transmittance can also be measured at very low energies. 相似文献
103.
Jiří Vondráček Emil PelikánOndřej Konár Jana ČermákováKryštof Eben Marek MalýMarek Brabec 《Applied Energy》2008
In this paper we present a statistical approach to natural gas consumption estimation of individual residential and small commercial customers. The approach is based on nonlinear regression principles. Parameters are estimated using mainly two real data sets – ordinary (approximately annual) meter readings of almost all customers and additional (approximately monthly) meter readings designed and operated within the frame of cooperation between the Institute of Computer Science of the Czech Academy of Sciences (ICS) and the West Bohemian Gas Distribution Company, a part of the RWE Group (WBG). The model was tested on various data sets. It has broad applicability in many areas of gas industry. 相似文献
104.
J. Čížek M. Vlček I. Procházka 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》2010,623(3):982-994
High-resolution digital coincidence Doppler broadening spectrometer equipped with two high-purity Ge detectors and two-channel 12-bit fast digitizer was developed and tested in this work. Two configurations were compared: (i) semi-digital setup which uses active analogue shaping of detector pulses prior to digitization to improve signal-to-noise ratio, and (ii) pure-digital setup which samples detector pulses directly. Software procedure developed for analysis of sampled waveforms, i.e. precise determination of energy of detected photon and rejection of distorted pulses, is described. Performance of digital coincidence spectrometer was compared with traditional analogue setup connected to the same detectors. It was found that digital spectrometer enables to achieve better energy resolution than in traditional analogue setup. Moreover, in digital configuration one has better control over shape of the signal. This allows efficient elimination of undesired distorted or damaged waveforms and to obtain spectrum of better clarity. The superior parameters of new digital coincidence Doppler broadening spectrometer are demonstrated by benchmark measurements of well defined Fe and Al specimens and also by the detection of rare annihilation in flight events. 相似文献
105.
Anolda Četkauskaitė Aurelijus Zimkus Jezi Borovik 《The International journal of environmental studies》2013,70(3):259-260
Pesticide toxicity databases usually include data on pure chemicals (active ingredients). Technical pesticides formulations, however, are mixtures with adjuvants as applied to fields/crops. Two formulations of the same pesticide can differ in their environmental fate and their toxicity. This work presents the evaluation of the toxicity of the dinitroaniline herbicide, pendimethalin by simultaneous analysis of its respiration rate and generation of a membrane potential (Δ Ψ) in rat liver mitochondria. Chromatography grade pendimethalin (8.2·10?5 ‐ 5.47·10?4 M or 23 – 154 ppm) caused lower enhancement of the mitochondrial respiration and decrease of the Δ Ψ than technical grade pendimethalin (Stomp), i.e. the mixture of pure ingredient and adjuvant(s). These effects are comparable to those of 2,4‐dinitrophenol. Pure and technical grade pendimethalin acts as an uncoupler of oxidative phosphorylation in mitochondria (enhances respiration and diminishes Δ Ψ). These data conflict with the statement, presented in the US EPA manual Recognition and Management of Pesticides Poisonings, that pendimethalin does not act as an uncoupler of oxidative phosphorylation. 相似文献
106.
Jiří Čtyroký 《Journal of Modern Optics》2013,60(6):1007-1015
Abstract The influence of branching asymmetry and electrode offset on the switching characteristics and cross-talk of X-type switches is analysed theoretically. The relationship between the switch symmetry (i.e. the existence of a plane or centre of inversion) and the switching characteristics is found. Cross-talk levels of slightly asymmetric Ti:LiNbO3 switches are calculated. 相似文献
107.
Nina Radić Bratislav M. Obradović Mirjana Kostić Biljana Dojčinović Milorad M. Kuraica Mirko Černák 《Surface & coatings technology》2012
The aim of this work is plasma activation of nonwoven polypropylene (PP) using two different ambient air plasma sources: volume dielectric barrier discharge (DBD) and diffuse coplanar surface barrier discharge (DCSBD) and its functionalization by silver ion deposition. 相似文献
108.
109.
Stojan Pečlin Primož Južnič Rok Blagus Mojca Čižek Sajko Janez Stare 《Scientometrics》2012,93(3):937-948
This study examines the effect of international collaboration of Slovenian authors and the status of journals where papers are published (as determined by their impact factors) on the impact of papers as measured by the number of citations papers receive. Research programme groups working in Slovenia in the 2004–2008 period in the fields of physics, chemistry, biology, biotechnology, and medical science were used for analyses. The results of the analyses show that the effects of the two factors differ among the fields. We discuss possible reasons for this, including the possibility that differences are the result of Slovenia’s science policy. 相似文献
110.
Although experimental observations determine the martensite structure of NiTi as monoclinic (B19′), ab-initio calculations show that, after a full optimization of the lattice, the ideal martensite structure relaxes into orthorhombic B33 one. This paper presents a first principles investigation of the structure of (100) compound twins in martensite. The results obtained by means of two different computational codes show that the optimized structure of twin cells is very close to that of B19′ martensite. This indicates that twinning can significantly contribute to mechanisms stabilizing the B19′ structure in real martensite samples. 相似文献