全文获取类型
收费全文 | 1710篇 |
免费 | 91篇 |
国内免费 | 8篇 |
专业分类
电工技术 | 24篇 |
综合类 | 9篇 |
化学工业 | 561篇 |
金属工艺 | 38篇 |
机械仪表 | 39篇 |
建筑科学 | 108篇 |
矿业工程 | 4篇 |
能源动力 | 37篇 |
轻工业 | 109篇 |
水利工程 | 12篇 |
无线电 | 104篇 |
一般工业技术 | 329篇 |
冶金工业 | 196篇 |
原子能技术 | 4篇 |
自动化技术 | 235篇 |
出版年
2023年 | 32篇 |
2022年 | 34篇 |
2021年 | 58篇 |
2020年 | 35篇 |
2019年 | 37篇 |
2018年 | 42篇 |
2017年 | 32篇 |
2016年 | 66篇 |
2015年 | 51篇 |
2014年 | 71篇 |
2013年 | 100篇 |
2012年 | 91篇 |
2011年 | 109篇 |
2010年 | 68篇 |
2009年 | 72篇 |
2008年 | 96篇 |
2007年 | 76篇 |
2006年 | 62篇 |
2005年 | 53篇 |
2004年 | 44篇 |
2003年 | 37篇 |
2002年 | 48篇 |
2001年 | 18篇 |
2000年 | 32篇 |
1999年 | 28篇 |
1998年 | 33篇 |
1997年 | 41篇 |
1996年 | 26篇 |
1995年 | 20篇 |
1994年 | 24篇 |
1993年 | 19篇 |
1992年 | 17篇 |
1991年 | 19篇 |
1990年 | 15篇 |
1989年 | 10篇 |
1988年 | 8篇 |
1987年 | 11篇 |
1986年 | 9篇 |
1985年 | 14篇 |
1984年 | 17篇 |
1983年 | 17篇 |
1982年 | 11篇 |
1981年 | 9篇 |
1980年 | 7篇 |
1979年 | 13篇 |
1978年 | 7篇 |
1976年 | 14篇 |
1975年 | 7篇 |
1974年 | 13篇 |
1969年 | 7篇 |
排序方式: 共有1809条查询结果,搜索用时 15 毫秒
121.
Dilute THF-solutions of different fractions of polymers of methyl, ethyl, n-propyl, n-, i- and t-butyl, n-hexyl, 2-ethylhexyl, and lauryl acrylate, prepared by solution polymerization in benzene, were studied by light scattering and viscosity methods. Poly(acrylic acid) was examined in dioxane. For the different polyacrylic esters the [η]-Mw-relations were established and the dependence of the radius of gyration <r2w> on the molecular weight was determined. 相似文献
122.
Tadeusz Jankowski 《Computing》1990,43(4):343-359
In this paper we develop a class of one-step methods combined with iterative methods to approximate the solution of retarded differential equations with parameters. The convergence theorems are established including the estimation of errors. Some methods are illustrated by three numerical examples. 相似文献
123.
Flavio Carbognani Felix Buergin Norbert Felber Hubert Kaeslin Wolfgang Fichtner 《Analog Integrated Circuits and Signal Processing》2008,56(1-2):5-12
The most widespread 16-bit multiplier architectures are compared in terms of area occupation, dissipated energy, and EDP (Energy-Delay Product) in view of low-power low-voltage signal processing for digital hearing aids and similar applications. Transistor-level simulations including back-annotated wire parasitics confirm that the propagation of glitches along uneven and re-convergent paths results in large unproductive node activity. Because of their shorter full-adder chains, Wallace-tree multipliers indeed dissipate less energy than the carry-save (CSM) and other traditional array multipliers (6.0 µW/MHz versus 10.9 µW/MHz and more for 0.25 µm CMOS technology at 0.75 V). By combining the Wallace-tree architecture with transmission gates (TGs), a new approach is proposed to improve the energy efficiency further (3.1 µW/MHz), beyond recently published low-power architectures. Besides the reduction of the overall capacitance, minimum-sized transmission gate full-adders act as RC-low-pass filters that attenuate undesired switching. Finally, minimum size TGs increase the V dd to ground resistance, hence decreasing leakage dissipation (0.55 nW versus 0.84 nW in CSM and 0.94 nW in Wallace). 相似文献
124.
125.
Rose Susan A.; Feldman Judith F.; Jankowski Jeffery J. 《Canadian Metallurgical Quarterly》2001,37(4):539
A span task was developed to assess the amount of information infants could hold in short-term memory. In this task, infants were presented with up to 4 items in succession and then tested for recognition by successively pairing each item with a novel one. A large sample of full-terms and low-birth-weight preterms ( 相似文献
126.
F. Stangenberg D. Jankowski 《International Journal of Pressure Vessels and Piping》1989,38(5):341-353
The behaviour of anchor bolts embedded in concrete and loaded in tension is investigated. Based on the state of the art of anchoring to concrete, a nonlinear finite-element model is developed, considering the influences on the behaviour and the maximum pull-out loads of anchorages. Special focus is given to the influences of concrete strength and of flexural reinforcement as well as of crack propagations in the concrete. 相似文献
127.
Visualisation of the structure transfer between an oriented polymer melt and the semi-crystalline state 总被引:1,自引:0,他引:1
Structure evolution of highly oriented polyethylene during cautious melting and crystallization is investigated with both high time resolution and high signal-to-noise ratio by means of small-angle X-ray scattering (SAXS) and wide-angle X-ray scattering (WAXS). The two-dimensional SAXS patterns are transformed to the multidimensional chord distribution function (CDF) in physical space. The results are continuous and smooth movies of the nanostructure, which elucidate the mechanisms of the evolution of semicrystalline structure.We find that in our material crystallization is preceeded by a rather diffuse mesomorphic nanostructure. Based on its variation in relation to other observed features like row nuclei and crystalline lamellae, we propose to associate it to phase separated regions of entangled and disentangled chain segments, respectively. The movies show that the mesophase structure holds the key for the understanding of crystallite orientation and arrangement in the fibre. 相似文献
128.
Gavin Lawes Simon C. J. Kingsley Andrei Golov Norbert Mulders James V. Porto Jeevak M. Parpia 《Journal of Low Temperature Physics》2000,121(5-6):567-572
We have investigated the superfluid transition of
3
He in different samples of silica aerogel. Several of these samples have been characterized using x-ray imaging, yielding information about the microstructure of the aerogel. In comparing new measurements on a 99.5% sample with previous observations on the behavior of
3
He in 98% porous aerogel we have found evidence for a scaling of the superfluid transition temperature to the correlation length of the aerogel. Furthermore, the superfluid density exhibits a similar universal behaviour over a range of values of reduced temperature. We discuss these new results in the context of superfluid pairing in the presence of a correlated disorder, specifically focussing on the fractal nature of the aerogel. 相似文献
129.
Effects of in‐situ functionalization of carbon nanotubes with bis(triethoxysilylpropyl) tetrasulfide (TESPT) and 3‐aminopropyltriethoxysilane (APTES) on properties of epoxidized natural rubber–carbon nanotube composites 下载免费PDF全文
Yeampon Nakaramontri Charoen Nakason Claudia Kummerlöwe Norbert Vennemann 《Polymer Engineering and Science》2015,55(11):2500-2510
Composites of carbon nanotubes (CNT) and epoxidized natural rubber (ENR) were prepared by in‐situ functionalization of CNT with two alternative silane coupling agents: bis(triethoxysilylpropyl) tetrasulfide (TESPT) and 3‐aminopropyltriethoxysilane (APTES). The reactions of ENR molecules with the functional groups on CNT surfaces and with the silane molecules were characterized by Fourier transform infrared. Furthermore, cross‐link density, relaxation behaviors, curing, mechanical, electrical, and morphological properties of pristine ENR and the ENR composites were investigated. Very low percolation thresholds, at CNT concentrations as low as 1 phr, were observed in the ENR–CNT and the ENR–CNT–TESPT composites. This might be attributed to improvements in the chemical linkages between ENR molecules and functional groups on CNT surfaces that led to a homogenous dispersion of CNTs in the ENR matrix, with loose CNT agglomerates. POLYM. ENG. SCI., 55:2500–2510, 2015. © 2015 Society of Plastics Engineers 相似文献
130.
Janina Schmitz Norbert Furtmann Moritz Ponert Dr. Maxim Frizler Dr. Reik Löser Prof. Dr. Ulrike Bartz Prof. Dr. Jürgen Bajorath Prof. Dr. Michael Gütschow 《ChemMedChem》2015,10(8):1365-1377
Cleavage of the invariant chain is the key event in the trafficking pathway of major histocompatibility complex class II. Cathepsin S is the major processing enzyme of the invariant chain, but cathepsin F acts in macrophages as its functional synergist which is as potent as cathepsin S in invariant chain cleavage. Dedicated low‐molecular‐weight inhibitors for cathepsin F have not yet been developed. An active site mapping with 52 dipeptide nitriles, reacting as covalent–reversible inhibitors, was performed to draw structure–activity relationships for the non‐primed binding region of human cathepsin F. In a stepwise process, new compounds with optimized fragment combinations were designed and synthesized. These dipeptide nitriles were evaluated on human cysteine cathepsins F, B, L, K and S. Compounds 10 (N‐(4‐phenylbenzoyl)‐leucylglycine nitrile) and 12 (N‐(4‐phenylbenzoyl)leucylmethionine nitrile) were found to be potent inhibitors of human cathepsin F, with Ki values <10 nM . With all dipeptide nitriles from our study, a 3D activity landscape was generated to visualize structure–activity relationships for this series of cathepsin F inhibitors. 相似文献