全文获取类型
收费全文 | 1034篇 |
免费 | 24篇 |
专业分类
电工技术 | 19篇 |
化学工业 | 230篇 |
金属工艺 | 27篇 |
机械仪表 | 21篇 |
建筑科学 | 48篇 |
矿业工程 | 23篇 |
能源动力 | 12篇 |
轻工业 | 107篇 |
水利工程 | 20篇 |
石油天然气 | 3篇 |
无线电 | 73篇 |
一般工业技术 | 175篇 |
冶金工业 | 146篇 |
原子能技术 | 8篇 |
自动化技术 | 146篇 |
出版年
2022年 | 17篇 |
2021年 | 18篇 |
2020年 | 17篇 |
2019年 | 11篇 |
2018年 | 11篇 |
2017年 | 11篇 |
2016年 | 25篇 |
2015年 | 19篇 |
2014年 | 32篇 |
2013年 | 49篇 |
2012年 | 53篇 |
2011年 | 59篇 |
2010年 | 44篇 |
2009年 | 44篇 |
2008年 | 45篇 |
2007年 | 45篇 |
2006年 | 32篇 |
2005年 | 28篇 |
2004年 | 33篇 |
2003年 | 22篇 |
2002年 | 33篇 |
2001年 | 14篇 |
2000年 | 22篇 |
1999年 | 24篇 |
1998年 | 26篇 |
1997年 | 23篇 |
1996年 | 14篇 |
1995年 | 15篇 |
1994年 | 14篇 |
1993年 | 11篇 |
1992年 | 13篇 |
1991年 | 15篇 |
1990年 | 9篇 |
1989年 | 7篇 |
1988年 | 14篇 |
1987年 | 19篇 |
1985年 | 10篇 |
1984年 | 11篇 |
1983年 | 12篇 |
1982年 | 8篇 |
1981年 | 7篇 |
1980年 | 8篇 |
1979年 | 9篇 |
1978年 | 7篇 |
1977年 | 12篇 |
1975年 | 10篇 |
1974年 | 6篇 |
1972年 | 8篇 |
1971年 | 6篇 |
1970年 | 7篇 |
排序方式: 共有1058条查询结果,搜索用时 0 毫秒
51.
Complex dewetting scenarios captured by thin-film models 总被引:1,自引:0,他引:1
In the course of miniaturization of electronic and microfluidic devices, reliable predictions of the stability of ultrathin films have a strategic role for design purposes. Consequently, efficient computational techniques that allow for a direct comparison with experiment become increasingly important. Here we demonstrate, for the first time, that the full complex spatial and temporal evolution of the rupture of ultrathin films can be modelled in quantitative agreement with experiment. We accomplish this by combining highly controlled experiments on different film-rupture patterns with computer simulations using novel numerical schemes for thin-film equations. For the quantitative comparison of the pattern evolution in both experiment and simulation we introduce a novel pattern analysis method based on Minkowski measures. Our results are fundamental for the development of efficient tools capable of describing essential aspects of thin-film flow in technical systems. 相似文献
52.
Van Houte H De Hoffmann E Van Veldhoven PP Mannaerts GP Carchon H Baes MI Declercq PE 《Lipids》2001,36(4):367-372
The goal of this study was to clarify the mechanism responsible for the catabolism of α-tocopherol. The vitamin, bound to
albumin, was incubated with rat liver microsomes and appeared to be broken down. Optimal production of the metabolite was
obtained when 1 mg of microsomal protein was incubated with 36 μM of α-tocopherol in the presence of 1.5 mM of NADPH. Chromatographic
and mass spectrometric analyses of the metabolite led to the conclusion that it consists of an ω-acid with an opened chroman
ring, although we could not perform nuclear magnetic resonance analysis to confirm this. Our data show that α-tocopherol is
ω-oxidized to a carboxylic acid and that this process can occur in rat liver microsomes in the presence of NADPH and O2. The oxidation to the quinone structure appears to be a subsequent event that may be artifactual and/or catalyzed by a microsomal
enzyme(s). 相似文献
53.
54.
Cross-validation (CV) is a very popular technique for model selection and model validation. The general procedure of leave-one-out CV (LOO-CV) is to exclude one observation from the data set, to construct the fit of the remaining observations and to evaluate that fit on the item that was left out. In classical procedures such as least-squares regression or kernel density estimation, easy formulas can be derived to compute this CV fit or the residuals of the removed observations. However, when high-breakdown resampling algorithms are used, it is no longer possible to derive such closed-form expressions. High-breakdown methods are developed to obtain estimates that can withstand the effects of outlying observations. Fast algorithms are presented for LOO-CV when using a high-breakdown method based on resampling, in the context of robust covariance estimation by means of the MCD estimator and robust principal component analysis. A robust PRESS curve is introduced as an exploratory tool to select the number of principal components. Simulation results and applications on real data show the accuracy and the gain in computation time of these fast CV algorithms. 相似文献
55.
This paper presents a thermodynamic study of Chemical Bath Deposition (CBD) of zinc sulphide based films in aqueous ammonia solutions. The aim is a better understanding of ammonia and temperature effects on the deposition conditions and films composition. The formation of solid phases has been predicted by means of the precipitation conditions of ZnO, Zn(OH)2 and ZnS as a function of temperature between 298 and 333 K. Films have been deposited according to calculated diagrams and preliminary results on solar cells based on electrodeposited CuIn(S,Se)2 layers have been demonstrated. Composition and thickness of the films have been extracted to link the theoretical study with experiments. 相似文献
56.
To avoid plasma induced erosion of chamber hardware, the application of remote plasma sources to activate the etch gases was introduced. We present results on the etch behaviour of titanium nitride (TiN) using mixtures of NF3, Cl2 and argon. The gas mixture was excited in a remote plasma source and then routed through a reaction chamber to study the etch behaviour of TiN samples which simulate the situation at the chamber walls. The dependency of the TiN etch rate on temperature, gas flow, composition and pressure was examined. While the temperature (studied in the range 25-300 °C) turned out to be the most sensitive parameter, the general etch rate was mainly dependent on the availability of atomic fluorine. Etch products and NF3/Cl2 dissociation have been monitored by quadrupole mass spectrometry and infrared spectroscopy. While NF3 showed a high decomposition up to 96%, chlorine decomposition was not observed. However the addition of chlorine increased the etch rates up to 260% in the low pressure/low temperature regime. Surface effects of chlorine addition are indicated by X-Ray Photoelectron Spectrometry and REM surface analysis. 相似文献
57.
Thomas Diemant Zhong Zhao Hubert Rauscher Joachim Bansmann R. Jürgen Behm 《Topics in Catalysis》2007,44(1-2):83-93
The interaction of CO with structurally well-defined, planar Au/TiO2 model catalysts at elevated pressures (up to 50 mbar) was studied in-situ by polarization-modulated infrared reflection absorption spectroscopy and ex-situ by X-ray photoelectron spectroscopy performed before and after CO exposure. The results indicate a CO-induced partial reduction
of the oxide surface, which is evidenced by a low frequency C–O vibration at 2060 cm−1, combined with a spreading of the Au nanoparticles due to a modification of the Au-oxide interface energy. In a 2:1 CO:O2 atmosphere, TiO2 support reduction was not observed, and a pre-reduced surface was re-oxidized. The consequences of these results for the
understanding of the CO oxidation mechanism on Au/TiO2 (model) catalysts are discussed. 相似文献
58.
Shifting the focus from futuristic visions, Alfredo Brillembourg and Hubert Klumpner with Alexis Kalagas of interdisciplinary design practice Urban-Think Tank urge us to ‘forget about utopia’, for in the most part the urban environment of 2050 is already built. Architects’ sights need to be set on the sometimes grim and unfolding reality of favelas and the world's informal cities. 相似文献
59.
Kseniya Khamina Andreas B. Diendorfer Susanna Skalicky Moritz Weigl Marianne Pultar Teresa L. Krammer Catharine Aquino Fournier Amy L. Schofield Carolin Otto Aaron Thomas Smith Nina Buchtele Christian Schoergenhofer Bernd Jilma Bernhard J. H. Frank Jochen G. Hofstaetter Regina Grillari Johannes Grillari Klemens Ruprecht Christopher E. Goldring Hubert Rehrauer Warren E. Glaab Matthias Hackl 《International journal of molecular sciences》2022,23(3)
60.
Gabriel Rinnerthaler Hubert Hackl Simon Peter Gampenrieder Frank Hamacher Clemens Hufnagl Cornelia Hauser-Kronberger Franz Zehentmayr Gerd Fastner Felix Sedlmayer Brigitte Mlineritsch Richard Greil 《International journal of molecular sciences》2016,17(2)
For quantitative microRNA analyses in formalin-fixed paraffin-embedded (FFPE) tissue, expression levels have to be normalized to endogenous controls. To investigate the most stably-expressed microRNAs in breast cancer and its surrounding tissue, we used tumor samples from primary tumors and from metastatic sites. MiRNA profiling using TaqMan® Array Human MicroRNA Cards, enabling quantification of 754 unique human miRNAs, was performed in FFPE specimens from 58 patients with metastatic breast cancer. Forty-two (72%) samples were collected from primary tumors and 16 (28%) from metastases. In a cross-platform analysis of a validation cohort of 32 FFPE samples from patients with early breast cancer genome-wide microRNA expression analysis using SurePrintG3 miRNA (8 × 60 K)® microarrays from Agilent® was performed. Eleven microRNAs could be detected in all samples analyzed. Based on NormFinder and geNorm stability values and the high correlation (rho ≥ 0.8) with the median of all measured microRNAs, miR-16-5p, miR-29a-3p, miR-126-3p, and miR-222-3p are suitable single gene housekeeper candidates. In the cross-platform validation, 29 human microRNAs were strongly expressed (mean log2-intensity > 10) and 21 of these microRNAs including miR-16-5p and miR-29a-3p were also stably expressed (CV < 5%). Thus, miR-16-5p and miR-29a-3p are both strong housekeeper candidates. Their Normfinder stability values calculated across the primary tumor and metastases subgroup indicate that miR-29a-3p can be considered as the strongest housekeeper in a cohort with mainly samples from primary tumors, whereas miR-16-5p might perform better in a metastatic sample enriched cohort. 相似文献