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101.
A cobalt metal‐organic framework with small pore size for adsorptive separation of CO2 over N2 and CH4 下载免费PDF全文
Mitchell R. Armstrong Dingke Wang Bin Mu Zhenfei Cheng Jichang Liu 《American Institute of Chemical Engineers》2017,63(10):4532-4540
In this study, a new cobalt‐based metal‐organic framework (MOF), [ (μ3‐OH)2(ipa)5(C3O2)(DMF)2] (CoIPA) was synthesized. The crystal structure analysis shows that CoIPA is constructed by Co6(μ3‐OH)2 units linked by isophthalic acid forming a sxb topology and it possesses a small pore size of about 4 Å. The new MOF has been characterized using multiple experimental methods. Monte Carlo and Molecular Dynamic simulations were employed to investigate adsorption equilibrium and kinetics in terms of capacity and diffusivity of CO2, N2, and CH4 on CoIPA. The gas adsorption isotherms collected experimentally were used to verify the simulation results. The activated CoIPA sample exhibits great gas separation ability at ambient conditions for CO2/N2 and CO2/CH4 with selectivity of around 61.4 and 11.7, respectively. The calculated self‐diffusion coefficients show a strong direction dependent diffusion behavior of target molecules. This high adsorption selectivity for both CO2/N2 and CO2/CH4 makes CoIPA a potential candidate for adsorptive CO2 separation. © 2017 American Institute of Chemical Engineers AIChE J, 63: 4532–4540, 2017 相似文献
102.
Hotchkiss PJ Jones SC Paniagua SA Sharma A Kippelen B Armstrong NR Marder SR 《Accounts of chemical research》2012,45(3):337-346
Transparent metal oxides, in particular, indium tin oxide (ITO), are critical transparent contact materials for applications in next-generation organic electronics, including organic light emitting diodes (OLEDs) and organic photovoltaics (OPVs). Understanding and controlling the surface properties of ITO allows for the molecular engineering of the ITO-organic interface, resulting in fine control of the interfacial chemistries and electronics. In particular, both surface energy matching and work function compatibility at material interfaces can result in marked improvement in OLED and OPV performance. Although there are numerous ways to change the surface properties of ITO, one of the more successful surface modifications is the use of monolayers based on organic molecules with widely variable end functional groups. Phosphonic acids (PAs) are known to bind strongly to metal oxides and form robust monolayers on many different metal oxide materials. They also demonstrate several advantages over other functionalizing moieties such as silanes or carboxylic acids. Most notably, PAs can be stored in ambient conditions without degradation, and the surface modification procedures are typically robust and easy to employ. This Account focuses on our research studying PA binding to ITO, the tunable properties of the resulting surfaces, and subsequent effects on the performance of organic electronic devices. We have used surface characterization techniques such as X-ray photoelectron spectroscopy (XPS) and infrared reflection adsorption spectroscopy (IRRAS) to determine that PAs bind to ITO in a predominantly bidentate fashion (where two of three oxygen atoms from the PA are involved in surface binding). Modification of the functional R-groups on PAs allows us to control and tune the surface energy and work function of the ITO surface. In one study using fluorinated benzyl PAs, we can keep the surface energy of ITO relatively low and constant but tune the surface work function. PA modification of ITO has resulted in materials that are more stable and more compatible with subsequently deposited organic materials, an effective work function that can be tuned by over 1 eV, and energy barriers to hole injection (OLED) or hole-harvesting (OPV) that can be well matched to the frontier orbital energies of the organic active layers, leading to better overall device properties. 相似文献
103.
Janet L. Armstrong M. John Matthewson Charles R. Kurkjian 《Journal of the American Ceramic Society》2000,83(12):3100-3109
Strength and dynamic fatigue behavior of silica fibers has been measured as a function of ambient humidity. Bare and polymer-coated fibers were compared to determine the influence of the coating. The results verify earlier work that suggests the degradation reaction is approximately second order with respect to humidity. However, we verify this result using rigorous data analysis techniques and, unlike the earlier work, the result is shown to be independent of the form of the kinetic model for crack growth. Trends in the calculated fatigue parameters illustrate that a simple exponential crack growth law best describes the humidity data. No significant differences were found between coated and bare fibers, provided the coated fibers were properly equilibrated. A data analysis methodology is given for obtaining valid reaction orders independently of the crack growth law form. 相似文献
104.
Effects of Zirconia on Microstructure and Dielectric Properties of Barium Titanate Ceramics 总被引:1,自引:0,他引:1
Timothy R. Armstrong Laurie E. Morgens Alena K. Maurice Relva C. Buchanan 《Journal of the American Ceramic Society》1989,72(4):605-611
Dielectric properties and structural characteristics of BaTiO3 ceramics are significantly influenced by small addition (2 wt%) of ZrO2 . SEM and TEM observations revealed enhanced microstructural uniformity and retarded grain growth depending on sintering temperature. Above 1320°C, Zr diffusion into the BaTiO3 lattice resulted in a chemical modification of the tetragonal structure and the development of core–shell grains. Below 1320°C, TEM analysis showed ZrO2 at the grain boundaries as discrete particles (∼0.03μm). X-ray diffraction analysis revealed a decrease in the axial (c/a) ratio with decreasing grain size. A corresponding decrease in the spontaneous polarization, and twinned domain structures, were also observed in the fine-grained ceramics. These samples also showed a flattened permittivity response with temperature and significantly lower losses. 相似文献
105.
E. Bruce Nauman Mathew Armstrong Jakub Horak 《Chemical Engineering and Processing: Process Intensification》2010
Conventional static mixers typically require high length to diameter ratios to be effective. This paper considers static mixers design to increase first appearance times in short, fat reactors. Three types are considered: conical baffles and annular baffles for tubular reactors and axial baffles for reactors with a rectangular cross-section. Relatively simple designs allow production increases (or reactor volume decreases) on the order of 20–50%. 相似文献
106.
Mixed Dimensional Coupling in Finite Element Stress Analysis 总被引:4,自引:0,他引:4
Many analysis models utilize finite elements of reduced dimension. However, to capture stress concentrations at local details,
it would be desirable to combine the reduced dimensional element types with higher dimensional elements in a single finite
element model. It is therefore important in such cases to integrate into the analyses some scheme for coupling the element
types that conforms to the governing equations of the problem. In this paper, a novel method that can correctly couple beams
to solids, beams to shells and shells to solids for elastic problems is presented. The approach adopted is to equate the work
done on either side of the interface between dimensions, and this leads to multi-point constraint equations, thus providing
a relationship among nodal degrees of freedom between the differing element types. Example results show that the proposed
technique does not introduce any spurious stresses at the dimensional interfaces.
ID="A1" Correspondence and offprint requests to: C. G. Armstrong, School of Mechanical and Manufacturing Engineering, The Queen's University of Belfast, Ashby Building,
Stranmillis Road, Belfast BT9 5AH, Northern Ireland. E-mail: c.armstrong@qub.ac.uk 相似文献
107.
Tony Armstrong 《今日电子》2006,(10):38-39,41
就由电池供电并以微硬盘(HDD)作为主要存储介质的手持产品而言,目前有3种市场驱动因素汇聚在一起,可能导致在这些便携式产品的电池工作时间方面产生极大的突破。这类便携式产品包括便携式播放器(PMP)、MP3播放器、数码相机(DSC)、数字录像机(DVR)、智能电话和GPS系统等。 相似文献
108.
Adam M. Fermier Alan R. Oyler Barbara L. Armstrong Bruce A. Weber Ramn L. Rodríguez James V. Weber James A. Nalasco 《Journal of The Association for Laboratory Automation》2002,7(1):83
An automated instrument was designed and constructed to facilitate the performance of pharmaceutical degradation studies. A brief theoretical background on degradation kinetics is given to rationalize the design of the instrument and representative data are provided to illustrate its successful application. This system was found to be capable of conducting multiple simultaneous isothermal and nonisothermal kinetic studies with user-defined temperature profiles, sampling periods, and data logging. 相似文献
109.
We consider some peculiarities of the evolution of processes of stimulated scattering in liquid transparent particles in the presence of ponderomotive action of a light field. We observed the occurrence of sharp deformations in the Descartes ring zone, which exceeds by more than 1 order of magnitude the deformations of the remaining particle surface. Investigation of the dynamics of the evolution of droplet deformations has made it possible to consider these deformations as the main cause of suppression of stimulated scattering indicated in the experiments. An analytical expression was derived to evaluate the decrease of the Q factor of droplet quasi-normal eigenmodes caused by perturbation of the particle shape from the spherical. Our study revealed that the larger the Q factor of the droplet eigenmodes, the greater the influence of surface deformation. 相似文献
110.
The sintering behavior of (La0.7Sr0.3)xCrO3 (0.95 x 1.05) is investigated to compare liquid phase sintering phenomena occuring in stoichiometric and non-stoichiometric compositions. Shrinkage analysis revealed marked contrast between the densification characteristics of the A-site enriched (x > 1.00) and A-site depleted (x < 1.00) materials. A-site depleted samples typically exhibited a single liquid phase sintering event at 1250 °C attributed to the melting of an exsoluted SrCrO4 phase. A-site enriched samples indicated two rapid shrinkage events due to the melting of SrCrO4, and a Sr2.67(CrO4)2 phase with a melting temperature of 1450 °C. Sr2.67(CrO4)2 was shown to evolve from a decomposition reaction between SrCrO4 and La2CrO6, detected together in A-site enriched samples from 800–1000 °C. Maximum densities (93% theoretical density) were achieved for (La0.7Sr0.3)xCrO3 x = 1.00 after sintering at 1700 °C for two hours. 相似文献