全文获取类型
收费全文 | 239篇 |
免费 | 11篇 |
专业分类
电工技术 | 2篇 |
化学工业 | 42篇 |
建筑科学 | 5篇 |
能源动力 | 2篇 |
轻工业 | 15篇 |
无线电 | 40篇 |
一般工业技术 | 50篇 |
冶金工业 | 35篇 |
原子能技术 | 1篇 |
自动化技术 | 58篇 |
出版年
2022年 | 3篇 |
2021年 | 4篇 |
2020年 | 2篇 |
2019年 | 5篇 |
2018年 | 5篇 |
2017年 | 2篇 |
2016年 | 7篇 |
2015年 | 3篇 |
2014年 | 9篇 |
2013年 | 16篇 |
2012年 | 14篇 |
2011年 | 21篇 |
2010年 | 21篇 |
2009年 | 11篇 |
2008年 | 15篇 |
2007年 | 15篇 |
2006年 | 8篇 |
2005年 | 5篇 |
2004年 | 9篇 |
2003年 | 5篇 |
2002年 | 5篇 |
2001年 | 8篇 |
2000年 | 4篇 |
1999年 | 3篇 |
1998年 | 7篇 |
1997年 | 8篇 |
1996年 | 9篇 |
1995年 | 1篇 |
1994年 | 5篇 |
1993年 | 4篇 |
1992年 | 6篇 |
1991年 | 1篇 |
1990年 | 3篇 |
1989年 | 1篇 |
1987年 | 1篇 |
1982年 | 1篇 |
1980年 | 1篇 |
1976年 | 2篇 |
排序方式: 共有250条查询结果,搜索用时 0 毫秒
101.
102.
Anat Eyal Tova Milo 《The VLDB Journal The International Journal on Very Large Data Bases》2001,10(1):16-38
A broad spectrum of electronic commerce applications is currently available on the Web, providing services in almost any
area one can think of. As the number and variety of such applications grow, more business opportunities emerge for providing
new services based on the integration and customization of existing applications. (Web shopping malls and support for comparative
shopping are just a couple of examples.) Unfortunately, the diversity of applications in each specific domain and the disparity
of interfaces, application flows, actor roles in the business transaction, and data formats, renders the integration and manipulation
of applications a rather difficult task. In this paper we present the Application Manifold system, aimed at simplifying the intricate task of integration and customization of e-commerce applications. The scope of
the work in this paper is limited to web-enabled e-commerce applications. We do not support the integration/customization
of proprietary/legacy applications. The wrapping of such applications as web services is complementary to our work. Based
on the emerging Web data standard, XML, and application modeling standard, UML, the system offers a novel declarative specification
language for describing the integration/customization task, supporting a modular approach where new applications can be added
and integrated at will with minimal effort. Then, acting as an application generator, the system generates a full integrated/customized
e-commerce application, with the declarativity of the specification allowing for the optimization and verification of the
generated application. The integration here deals with the full profile of the given e-commerce applications: the various
services offered by the applications, the activities and roles of the different actors participating in the application (e.g.,
customers, vendors), the application flow, as well as with the data involved in the process. This is in contrast to previous
works on Web data integration that focused primarily on querying the data available in the applications, mostly ignoring the
additional aspects mentioned above.
Received: 30 October 2000 / Accepted 14 March 2001 Published online: 2 August 2001 相似文献
103.
Elahipanah Ava; Christensen Bruce K.; Reingold Eyal M. 《Canadian Metallurgical Quarterly》2010,24(2):192
The current study investigated one possible mechanism of impaired visual attention among patients with schizophrenia: a reduced visual span. Visual span is the region of the visual field from which one can extract information during a single eye fixation. This study hypothesized that schizophrenia-related visual search impairment is mediated, in part, by a smaller visual span. To test this hypothesis, 23 patients with schizophrenia and 22 healthy controls completed a visual search task where the target was pseudorandomly presented at different distances from the center of the display. Response times were analyzed as a function of search condition (feature vs. conjunctive), display size, and target eccentricity. Consistent with previous reports, patient search times were more adversely affected as the number of search items increased in the conjunctive search condition. It was important however, that patients’ conjunctive search times were also impacted to a greater degree by target eccentricity. Moreover, a significant impairment in patients’ visual search performance was only evident when targets were more eccentric and their performance was more similar to healthy controls when the target was located closer to the center of the search display. These results support the hypothesis that a narrower visual span may underlie impaired visual search performance among patients with schizophrenia. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
104.
Participants' eye movements were monitored while they read sentences in which high-frequency and low-frequency target words were presented either in normal font (e.g., account) or case alternated (e.g., aCcOuNt). The influence of the word frequency and case alternation manipulations on fixation times was examined. Although both manipulations had comparable effects on standard first-pass fixation measures, word frequency, but not case alternation was found to influence the duration of the first fixation in trials with multiple first-pass fixations. Assuming that lexical processing is more often incomplete at the termination of the first in multiple first-pass fixations than at the end of single first-pass fixations, the present findings provide strong evidence for an influence of word frequency on early lexical processing. Importantly, such a demonstration of a fast acting influence of a lexical variable on fixation times satisfies a critical prerequisite for establishing lexical control of eye movements in reading. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
105.
Nan Shen Eyal Feigenbaum Tayyab Suratwala William Steele Lana Wong Michael D. Feit Phil E. Miller 《Journal of the American Ceramic Society》2019,102(6):3141-3151
The nanomechanical deformations on a broad range of optical material surfaces (single crystals of Al2O3 [sapphire], SiC, Y3Al5O12 [YAG], CaF2, and LiB3O5 [LBO]; a SiO2–Al2O3–P2O5–Li2O glass-ceramics [Zerodur]; and glasses of SiO2:TiO2 [ULE], SiO2 [fused silica], and P2O5–Al2O3–K2O–BaO [Phosphate]) near the elastic-plastic load boundary have been measured by nanoindentation and nanoscratching to mimic the nanoplastic removal caused by a single slurry particle during polishing. Nanoindenation in air was performed to determine the workpiece hardness at various loads using a commercial nanoindenter with a Berkovich tip. Similarly, an atomic force microscope (AFM) with a stiff diamond coated tip (150 nm radius) was used to produce nanoplastic scratches in air and aqueous environments over a range of applied loads (~20-170 μN). The resulting nanoplastic deformation of the nanoscratches were used to calculate the removal function (i.e., depth per pass) which ranged from 0.18 to 3.6 nm per pass for these materials. A linear correlation between the nanoplastic removal function and the polishing rate (using a fixed polishing process with colloidal silica slurry on a polyurethane pad) of these materials was observed implying that: (a) the polishing mechanism using colloidal silica slurry can be dominated by mechanical rather than chemical interactions; and (b) the nanoplastic removal function, as opposed to interface particle interactions, is the controlling factor for the polishing material removal rate. Furthermore, this correlation is consistent with the Ensemble Hertzian Multi-Gap (EHMG) microscopic material removal rate model described previously. The nanoplastic removal depth was also found to correlate to the measured nanoindentation hardness (H1) of the optical material, scaling as H1−3.5. Two-dimensional (2D) finite element analysis simulations of nanoindentation showed a similar nonlinear dependence of plastic deformation with the workpiece material hardness. The findings of this study are used to determine an effective Preston coefficient for the material removal rate expression and enhance the predictive nature of the nanoplastic polishing rate for various materials utilizing their material properties. 相似文献
106.
Aharon M. Eyal 《溶剂提取与离子交换》2013,31(6):951-969
Literature on HF extraction by amines and by tributyl phosphate is critically reviewed. The system amine-HF-H2O shows an interesting feature concerning properties such as distribution curves compared to those for extraction of other acids, similarity to extraction by TBP, water extraction, selectivity, effect of amine type and dilution and diluent effect These properties sharply change (or even invert) when HF/amine molar ratio exceeds 2. 相似文献
107.
ABSTRACT Solvent extraction of titanium(IV) from hydrochloric acid solutions by mixtures of mono- and di-2-ethylhexyl phosphoric acid esters (MEHPA and DEHPA) has been investigated as a function of HC1 concentration in the aqueous phase and extractants concentration in the organic phase It was found that MEHPA extracts Ti, 3 orders of magnitude more efficiently than DEHPA. Efficiency of extraction by MEHPA does not depend on acid concentration in the aqueous phase in the range of 0·1 – 8·8 mole/Kg. As a rule Ti/MEHPA ratio in the complex is 1/2. At low aqueous phase acidities (0·1–1·0 mole/Kg HCl) formation of six- (or eight-) coordinate bidentate hydrated Ti(IV)-2MEHPA complexes is suggested. At acidities above 7·0 mole/Kg HC1 titanium forms tridentate six- (or eight-) coordinate complexes. At medium acidities (2·0–6·0 mole/Kg HCl) mixtures of these complexes are formed. Prolonged mixing of the phases or aging of the organic phase leads to dehydration and to transformation of bidentate to tridentate Ti-2MEHPA complexes. Ti-2MEHPA complexes are colorless At ratios Ti/MEHPA<0·5 formation of Ti-MEHPA hydrated or solvated complex ions is suggested which form emulsion in the aqueous phase. These species slowly react with DEHPA and formation of Ti:MEHPA:DEHPA=1:1:2 complex is realized. This complex is yellow. 相似文献
108.
Porogen derived membranes, formed on decomposition of porogen molecules homogeneously dispersed in premembranes, were divided into two groups according to permeability and permeation mechanism. The more open membranes were formed when premembranes were cast on nonwoven polyester cloth support, or when decomposition products were extracted by solvent. The molecular cut off found for these membranes was at about 1000 Daltons and permeability was mainly determined by permeants' diffusivity and concentration. Permeability through the denser membrane was mainly determined by the permeants' partial vapor pressure, leading to high permselectivities. These denser membranes allowed relatively high osmotic water permeation while practically blocking permeation of solutes, such as salt, in the opposite direction. These membranes were thus also suitable for concentration of aqueous solutions by water removal into concentrated electrolyte solutions. © John Wiley & Sons, Inc. 相似文献
109.
Multi‐wall CNT/poly[ethylene‐co‐(methacrylic acid)] composites were prepared by melt mixing. To improve dispersion and promote polymer/nanotube interactions, a novel non‐covalent compatibilizer is synthesized by reacting the polymer with 4‐(aminomethyl)pyridine. The composite based on the pristine polymer shows electrical and rheological percolation thresholds at nanotube loadings of 1.85 and 1.4 wt%, respectively. When 5 wt% of the pyridine‐modified compatibilizer is added, the corresponding values are reduced to 1.44 and 0.8 wt%, respectively. The electrical resistivity decreases even further as 10 wt% of the novel dispersing agent is used. Microscopy and Raman spectroscopy confirm the improved dispersion and π‐interactions established during melt mixing.
110.
A platform of starch complexes for the oral release of aroma substances by salivary fluids was studied. Menthone, menthol and limonene were used as model flavor compounds for complexation with starches with different amylose content. Complexes were characterized by X-ray diffraction (XRD), differential scanning calorimetry (DSC), dynamic light scattering (DLS), and atomic force microscopy (AFM). Aroma retention was tested under pH, temperature and storage challenges. Furthermore, the kinetic of aroma release in simulated saliva fluids (SSF) was also tested. Both menthone and menthol form V-amylose complexes in a ’food grade’ process while limonene does not form such complexes efficiently. Complexation yield was higher, with more included aroma and less free core content, as the amylose content increased. The complexes had melting temperature of over 90 °C. Digestion results suggest that the complexes can release the aroma in the oral cavity. 相似文献