全文获取类型
收费全文 | 5518篇 |
免费 | 395篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 27篇 |
综合类 | 9篇 |
化学工业 | 1587篇 |
金属工艺 | 59篇 |
机械仪表 | 67篇 |
建筑科学 | 296篇 |
矿业工程 | 80篇 |
能源动力 | 87篇 |
轻工业 | 1001篇 |
水利工程 | 54篇 |
石油天然气 | 24篇 |
无线电 | 263篇 |
一般工业技术 | 812篇 |
冶金工业 | 871篇 |
原子能技术 | 22篇 |
自动化技术 | 658篇 |
出版年
2023年 | 55篇 |
2022年 | 149篇 |
2021年 | 218篇 |
2020年 | 107篇 |
2019年 | 134篇 |
2018年 | 149篇 |
2017年 | 166篇 |
2016年 | 226篇 |
2015年 | 177篇 |
2014年 | 245篇 |
2013年 | 396篇 |
2012年 | 300篇 |
2011年 | 393篇 |
2010年 | 291篇 |
2009年 | 245篇 |
2008年 | 295篇 |
2007年 | 266篇 |
2006年 | 235篇 |
2005年 | 167篇 |
2004年 | 175篇 |
2003年 | 141篇 |
2002年 | 134篇 |
2001年 | 92篇 |
2000年 | 88篇 |
1999年 | 75篇 |
1998年 | 79篇 |
1997年 | 82篇 |
1996年 | 66篇 |
1995年 | 64篇 |
1994年 | 61篇 |
1993年 | 50篇 |
1992年 | 51篇 |
1991年 | 41篇 |
1990年 | 53篇 |
1989年 | 36篇 |
1988年 | 49篇 |
1987年 | 38篇 |
1986年 | 27篇 |
1985年 | 26篇 |
1984年 | 40篇 |
1983年 | 23篇 |
1982年 | 32篇 |
1981年 | 12篇 |
1980年 | 20篇 |
1979年 | 31篇 |
1978年 | 14篇 |
1977年 | 13篇 |
1975年 | 18篇 |
1974年 | 8篇 |
1969年 | 8篇 |
排序方式: 共有5917条查询结果,搜索用时 15 毫秒
1.
2.
Ricardo Beristain‐Cardoso Anne‐Claire Texier Reyes Sierra‐Álvarez Jim A Field Elías Razo‐Flores Jorge Gómez 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2008,83(9):1197-1203
BACKGROUND: Simultaneous removal of sulfur, nitrogen and carbon compounds from wastewaters is a commercially important biological process. The objective was to evaluate the influence of the CH3COO?/NO3? molar ratio on the sulfide oxidation process using an inverse fluidized bed reactor (IFBR). RESULTS: Three molar ratios of CH3COO?/NO3? (0.85, 0.72 and 0.62) with a constant S2?/NO3? molar ratio of 0.13 were evaluated. At a CH3COO?/NO3? molar ratio of 0.85, the nitrate, acetate and sulfide removal efficiencies were approximately 100%. The N2 yield (g N2 g?1 NO3?‐N consumed) was 0.81. Acetate was mineralized, resulting in a yield of 0.65 g inorganic‐C g?1 CH3COO?‐C consumed. Sulfide was partially oxidized to S0, and 71% of the S2? consumed was recovered as elemental sulfur by a settler installed in the IFBR. At a CH3COO?/NO3? molar ratio of 0.72, the efficiencies of nitrate, acetate and sulfide consumption were of 100%, with N2 and inorganic‐C yields of 0.84 and 0.69, respectively. The sulfide was recovered as sulfate instead of S0, with a yield of 0.92 g SO42?‐S g?1 S2? consumed. CONCLUSIONS: The CH3COO?/NO3? molar ratio was shown to be an important parameter that can be used to control the fate of sulfide oxidation to either S0 or sulfate. In this study, the potential of denitrification for the simultaneous removal of organic matter, sulfide and nitrate from wastewaters was demonstrated, obtaining CO2, S0 and N2 as the major end products. Copyright © 2008 Society of Chemical Industry 相似文献
3.
在基于项目的组织中实现创新 在本节我们将探讨如何在项目环境中进行创新.首先我们来了解一下人们进行改变,进而实现创新的规律;然后我们介绍两种截然不同的管理创新的方法,即常用的线性推理方法和有机推进法;最后,我们对它们的优缺点做一个比较,看看它们各自适用于什么情况. 相似文献
4.
Minh Lequan Rose Marie Lequan Kathleen Chane-ching Anne-claude Callier Marguerite Barzoukas Alain Fort 《Advanced functional materials》1992,1(5):243-247
Samples of {4-(dimethylamino) stilben Z & E 4'-yl} dimesityl borane (BNS) were synthesised and investigated for their non-linear optical properties. The results show that the quadratic hyperpolarisability of the Z-isomer is smaller than that of the E-isomer, the beta value found for the latter being as high as 60 × 10?30 esu. 相似文献
5.
It is well known that the tearing resistance curve J–Δa is not a material property. A recent approach, based on an energetic critical parameter to model ductile tearing propagation, is used to model 3D effects. The approach considered in this work aims to estimate the dissipated energy in the fracture process during ductile tearing represented by an intrinsic parameter Gfr. A fracture criterion, which accounts for the crack extension length, is defined and lies on a critical energy release rate, noted Gc, which is compared to Gfr. Previously, this parameter was obtained from a numerical local energy release rate, which handicaps the application field of the approach: a fine mesh for the whole propagation area was needed and the criterion allowed only to model 1D propagation. A new manner to estimate Gc is then proposed in this article, based on the J plastic part variation, which allows to model 2D propagation by defining a local criterion. This new calculation method is validated on a CT specimen made in Tu52b ferritic steel, by comparing the results obtained from the two methods of Gc calculation. Then, the 2D crack growth case is studied, by modelling the propagation in a ring, loaded in compression. It is shown that a 3D effect, such as tunnel effect, could be successfully represented with this approach. 相似文献
6.
O'Farrell Timothy J.; Fals-Stewart William; Murphy Marie; Murphy Christopher M. 《Canadian Metallurgical Quarterly》2003,71(1):92
This study examined partner violence in the year before and the year after individually based, outpatient alcoholism treatment for 301 married or cohabiting male alcoholic patients and used a demographically matched nonalcoholic comparison sample. In the year before treatment, 56% of the alcoholic patients had been violent toward their female partner, 4 times the rate of 14% in the comparison sample. In the year after treatment, violence decreased significantly to 25% of the alcoholic sample but remained higher than in the comparison group. Among remitted alcoholics after treatment, violence prevalence of 15% was nearly identical to the comparison sample and half the rate among relapsed patients (32%). Thus, partner violence decreased after alcoholism treatment, and clinically significant violence reductions occurred for patients whose alcoholism was remitted after treatment. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
7.
8.
Summary A derivation of a parallel algorithm for rank order filtering is presented. Both derivation and result differ from earlier designs: the derivations are less complicated and the result allows a number of different implementations. The same derivation is used to design a collection of priority queues. Both filters and priority queues are highly efficient: they have constant response time and small latency.
Anne Kaldewaij received an M.Sc. degree in Mathematics from the University of Utrecht (The Netherlands) and a Ph.D. degree in Computing Science from the Eindhoven University of Technology. Currently, he is associate professor in Computing Science at Eindhoven University. His research includes parallel programming and the design of algorithms and data structures. He enjoys teaching and he has written a number of textbooks on mathematics and programming.
Jan Tijmen Udding received an M.Sc. degree in Mathematics in 1980 and a Ph.D. degree in Computing Science in 1984 from Eindhoven University of Technology. Currently, he is associate professor at Groningen University. His main research interests are mathematical aspects of VLSI, program derivation and correctness, and functional programming. 相似文献
9.
Wood has long traditions as a building material, and is often used in construction elements, and as interior and exterior surfaces in the Nordic countries. In most applications, there are reaction to fire requirements to products used as surfaces, e.g. in escape routes and larger public spaces. Most wood products will therefore have to be treated with fire retardant (FR) agents to fulfil the strict requirements to properties connected to heat release and flame spread. Unfortunately, FR agents usually also increase the smoke production, as they cause a more incomplete combustion of the wood. The wood product manufacturers seek to find the optimal amount of FR additives where both heat release and smoke production in the classifying test are within the requirements given in the building regulations. This paper describes models for prediction of the European reaction to fire classes of wood products. The models are based on multivariate statistical analysis, and use test results from the cone calorimeter test as input. The presented models are, with very good precision, able to predict which Euroclass and additional smoke class a wood based product would obtain if it were to be tested in the single burning item test. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
10.
Marie Alonso 《印刷技术》2002,(5)
当数码印刷、种类繁多的承印物以及经过改进的覆膜技术为印制精美耐用的户内、户外广告招贴的应用开辟了一条新的道路,建立了一种宽渠道的盈利模式时,宽幅印刷已经走向 相似文献