全文获取类型
收费全文 | 1657篇 |
免费 | 77篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 19篇 |
综合类 | 2篇 |
化学工业 | 567篇 |
金属工艺 | 47篇 |
机械仪表 | 59篇 |
建筑科学 | 30篇 |
矿业工程 | 4篇 |
能源动力 | 60篇 |
轻工业 | 132篇 |
水利工程 | 2篇 |
石油天然气 | 3篇 |
无线电 | 109篇 |
一般工业技术 | 231篇 |
冶金工业 | 125篇 |
原子能技术 | 6篇 |
自动化技术 | 341篇 |
出版年
2023年 | 13篇 |
2022年 | 90篇 |
2021年 | 94篇 |
2020年 | 38篇 |
2019年 | 41篇 |
2018年 | 39篇 |
2017年 | 59篇 |
2016年 | 65篇 |
2015年 | 49篇 |
2014年 | 88篇 |
2013年 | 122篇 |
2012年 | 80篇 |
2011年 | 84篇 |
2010年 | 72篇 |
2009年 | 79篇 |
2008年 | 85篇 |
2007年 | 57篇 |
2006年 | 61篇 |
2005年 | 36篇 |
2004年 | 41篇 |
2003年 | 43篇 |
2002年 | 26篇 |
2001年 | 16篇 |
2000年 | 22篇 |
1999年 | 13篇 |
1998年 | 27篇 |
1997年 | 33篇 |
1996年 | 27篇 |
1995年 | 23篇 |
1994年 | 18篇 |
1993年 | 19篇 |
1992年 | 13篇 |
1991年 | 14篇 |
1990年 | 8篇 |
1989年 | 6篇 |
1988年 | 15篇 |
1987年 | 7篇 |
1986年 | 4篇 |
1985年 | 8篇 |
1984年 | 9篇 |
1983年 | 18篇 |
1982年 | 6篇 |
1981年 | 8篇 |
1980年 | 10篇 |
1979年 | 5篇 |
1978年 | 8篇 |
1977年 | 7篇 |
1976年 | 4篇 |
1973年 | 4篇 |
1971年 | 6篇 |
排序方式: 共有1737条查询结果,搜索用时 15 毫秒
11.
In this paper, we continue the research on formal treatment of attributes of information, based on the computational approach. In this scenario, the usefulness of advisory information is measured by the decrease in complexity of a problem we need to solve. We propose to model the time criticality via usefulness of a piece of information which is received during the computation. As a modeling tool, we use deterministic finite automata. 相似文献
12.
Threats on the stability of a financial system may severely affect the functioning of the entire economy, and thus considerable emphasis is placed on the analyzing the cause and effect of such threats. The financial crisis in the current and past decade has shown that one important cause of instability in global markets is the so-called financial contagion, namely the spreadings of instabilities or failures of individual components of the network to other, perhaps healthier, components. This leads to a natural question of whether the regulatory authorities could have predicted and perhaps mitigated the current economic crisis by effective computations of some stability measure of the banking networks. Motivated by such observations, we consider the problem of defining and evaluating stabilities of both homogeneous and heterogeneous banking networks against propagation of synchronous idiosyncratic shocks given to a subset of banks. We formalize the homogeneous banking network model of Nier et al. (J. Econ. Dyn. Control 31:2033–2060, 2007) and its corresponding heterogeneous version, formalize the synchronous shock propagation procedures outlined in (Nier et al. J. Econ. Dyn. Control 31:2033–2060, 2007; M. Eboli Mimeo, 2004), define two appropriate stability measures and investigate the computational complexities of evaluating these measures for various network topologies and parameters of interest. Our results and proofs also shed some light on the properties of topologies and parameters of the network that may lead to higher or lower stabilities. 相似文献
13.
Sintered negative electrodes for nickel-cadmium secondary cells were studied. Model electrodes prepared by means of three different impregnation methods were evaluated. It was demonstrated that the impregnation procedure may affect properties of active mass and the service life of electrodes in a significant way. 相似文献
14.
15.
16.
1H-NMR and Eu(fod)3 lanthanide shift reagent were used to determine tetrad distribution of comonomer units of the PDT/FT copolyterephthalate obtained from terephthaloyl chloride (intermonomer) and 3,3′-dimethylbisphenol A and phenolphtalein (comonomers). Computer simulations of the terephthalic proton signal split into the lines of compositional tetrads were performed to obtain quantitative data. To characterize the microstructure of the copolymer samples synthesized at different temperatures, the degree of randomness and the degree of alternation were calculated. It was shown that the latter can differentiate the chains which seemed to be identical concerning the diad distribution only. 相似文献
17.
The effects of homopolymer and copolymer compositions and structures in styrene/n-butyl acrylate (Sty/BA) latices on sodium dioctyl sulfosuccinate (SDOSS) surfactant mobility and its preferential concentration at the film–air (F–A) and film–substrate (F–S) interfaces were examined using attenuated total reflectance Fourier transform infrared (ATR FTIR) spectroscopy. It appears that the SDOSS concentration at the F–S interface is highest when the Sty/BA feed ratio is 50/50, and the excess of Sty results in migration of SDOSS surfactant to the F–A interface. This behavior is attributed to the increased glass transition temperature and diminished compatibility between surfactant molecules and copolymer latex. This study also shows that the primary factors that influence exudation to either F–A or F–S interfaces are surface tension of the substrate, glass transition temperature, water flux during coalescence, and compatibility between latex components. © 1995 John Wiley & Sons, Inc. 相似文献
18.
The adsorption of acetonitrile and reduction of adsorbed molecules at platinized platinum electrode were studied by potentiodynamic and radiometric techniques. During acetonitrile adsorption the reversibly and irreversibly adsorbed species are formed. One electron reduction process occurs in the potential range 0.45-0.15 V. Below 0.15 V the deeper reduction of adsorbed acetonitrile takes place — the final products are ammonia and ethane. The differences of smooth and platinized platinum electrodes properties are briefly discussed. 相似文献
19.
Pt–Ba/MeO (where MeO = Al2O3, CeO2, SiO2 and ZrO2) NO
x
storage-reduction catalysts with Ba-loading varying from 0 wt.% to 28 wt.% were investigated concerning stability of Ba phases
and NO
x
storage-reduction efficiency. For Pt–Ba/Al2O3 three different Ba-containing phases with different thermal stability are distinguished based on their interaction with the
support. The relative concentration of these phases varies with the Ba-loading and NO
x
storage tests indicated that the BaCO3 phase decomposing between 400 °C and 800 °C (LT-BaCO3) is the most efficient Ba containing phase for NO
x
storage. Similar investigations of Pt–Ba catalysts supported on CeO2, SiO2 and ZrO2 showed that the relative amount of LT-BaCO3 phase depends also on the support material. NO
x
storage measurements confirmed a correlation between the concentration of LT-BaCO3 and NO
x
storage efficiency. Basicity and textural properties of the support are identified as crucial parameters for efficient NO
x
storage catalysts. 相似文献
20.
Marek Gryta 《Desalination》2002,142(1):79-88
Growth of microorganism in the membrane distillation (MD) system has been evaluated, and their presence on the membrane surface was studied using scanning electron microscopy (SEM) coupled with energy dispersion spectrometry (EDS). The membrane samples were collected from MD modules used for the following applications: concentration of salts and acids, production of demineralized water from tap water, separation of ethanol from fermentation broth in a membrane bioreactor and treatment of saline wastewater containing Pseudomonas and Streptococcus faecalis bacteria and Penicillium and Aspergillus fungi. The MD experiments were performed with polypropylene capillary membranes. SEM examinations of the membranes used for the treatment of saline wastewater indicated a significant amount of S. faecalis bacteria and Aspergillus fungi. The polypropylene membranes used did not reject S. faecalis bacteria, which were detected on the membrane surface on the distillate side. The presence of fungi in the membrane pores was observed only on the feed side. The contamination of the membrane surface by yeast cells was not observed in the case of the membrane bioreactor operated over one year. The running conditions of the MD process (such as elevated temperature, significant salt concentrations and low pH values) inhibited the growth of microorganism in the MD system. 相似文献