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91.
Three‐dimensional modeling of porosity development during the gasification of a char particle 下载免费PDF全文
Kay Wittig Petr A. Nikrityuk Sebastian Schulze Andreas Richter 《American Institute of Chemical Engineers》2017,63(5):1638-1647
This work is devoted to the three‐dimensional, direct modeling of porosity and specific surface development during the gasification of a char particle. The model was developed for heterogeneous reactions occurring inside a char particle in a kinetically controlled regime. The main goal of this work is to analyze the impact of different pore size distributions on the particle carbon conversion rate. In particular, it is shown that under certain conditions the outer particle surface can influence the specific surface area. In this context the possible adaptation of the parameter ψ from the random pore model (RPM) developed by Bhatia and Perlmutter is explained. The results of simulations are compared against the RPM and discussed. Additionally, based on the results of simulations, the physics behind several input parameters used by the RPM are explored. Finally, the possible fragmentation of a chemically reacting char particle during its gasification in dependence of instantaneous porosity was investigated numerically. It was shown that the earliest fragmentation occurs at a carbon conversion of about 0.5–0.6 due to the disaggregation of the pore walls. The results are discussed and compared implicitly with data published in the literature. © 2016 American Institute of Chemical Engineers AIChE J, 63: 1638–1647, 2017 相似文献
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Jana Dulle Silke Nemeth Ekaterina V. Skorb Torsten Irrgang Jürgen Senker Rhett Kempe Andreas Fery Daria V. Andreeva 《Advanced functional materials》2012,22(15):3128-3135
This paper proposes a sonochemical approach to the nanostructuring of Al/Ni catalyst with high content of accessible Ni centers and a high reusability. The surface and bulk composition as well as pore size distribution of this catalyst are controlled synergistically by adjusting the ultrasound intensity in aqueous solution. Sonochemical activation of Al/Ni alloy leads to formation of mesoporous Al/Ni metallic based frameworks with surface area up to 125 m2 g?1, and regular distribution of nickel active center in the porous matrix. One of the opportunities of porous Al/Ni catalyst is that due to a time‐resolved controllable formation of protective oxide layer it can be stored and handled under air in comparison to traditional Raney catalysts which need inert conditions. The Al/Ni catalyst is characterized by scanning electron microscopy (SEM), electron diffraction spectroscopy (EDS), X‐ray photoelectron spectroscopy (XPS), confocal scanning fluorescence microscopy (CSFM), solid‐state NMR experiments, and powder X‐ray diffraction analysis (PXRD). The catalytic activity was investigated for the hydrogenation of acetophenone. 相似文献
94.
Synthesis of 2-Heterocyclidenamino-1, 3-diaza-trimethincyanines The synthesis of 2-[3-methyl-benzthiazol-(1, 3)-inylidene-(2)-amino]- and of substituted 2-[1, 3-dithiolyliden-(2)-amino]-1, 3-diaza-trimethincyanines is described. The heterocyclic imines 1 react with phosgene or thiophosgene to the corresponding ureas 2 and thiureas 3 , respectively. Alkylation of 3 to the 2-alkylmercapto-1, 3-diaza-trimethincyanines 4 and subsequent condensation with imine 1 yields the dyes 5 . The chemical and spectroscopical data of cyanines 5 are described. 相似文献
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A social network perspective helps identify and analyse informal knowledge transfer among people and organisations with the
aim to recommend organisational interventions and improvements, for example in the form of Information and Communication Technology
(ICT) support. This paper particularly focuses on a key concept of social network analysis (SNA), the concept of tie strength,
in an inter-organisational knowledge transfer context. Tie strength describes the strength of a social relationship. In the
past, SNA literature with a knowledge management context has often emphasized the importance of strong and/or weak ties rather
than of intermediate (medium strong) ties in a social network. Nevertheless, in this study, intermediate ties are identified
as the dominant links among key groups of organisation in a social network. Intermediate ties also help connect otherwise
weakly linked organisations. Moreover, a definition of intermediate ties in the context of knowledge management is introduced.
With the help of cluster analysis and an investigation into the levels of reciprocity, intermediate ties can be clearly defined
in a social network. Due to their importance for knowledge transfer in a social network, intermediate ties should be primarily
supported, for example by appropriate ICT. 相似文献
99.
Dou Wenwen Jeong Dong Hyun Stukes Felesia Ribarsky William Lipford Heather Richter Chang Remco 《Computer Graphics and Applications, IEEE》2009,29(3):52-61
Understanding how analysts use visual-analytics (VA) tools can help reveal their reasoning processes when using these tools. By examining analysts' interaction logs, the authors identified the analysts' strategies, methods, and findings when using a financial VA tool. 相似文献
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Ebinghaus R Kock HH Temme C Einax JW Lowe AG Richter A Burrows JP Schroeder WH 《Environmental science & technology》2002,36(6):1238-1244
Unlike other heavy metals that are inherently associated with atmospheric aerosols, mercury in ambient air exists predominantly in the gaseous elemental form. Because of its prolonged atmospheric residence time, elemental mercury vapor is distributed on a global scale. Recently, Canadian researchers have discovered that total gaseous mercury levels in the lower tropospheric boundary layer in the Canadian Arctic are often significantly depleted during the months after polar sunrise. A possible explanation may involve oxidation of elemental mercury, followed by adsorption and deposition of the oxidized form, leading to an increased input of atmospheric mercury into the Arctic ecosystem. Here we present the first continuous high-time-resolution measurements of total gaseous mercury in the Antarctic covering a 12-month period between January 2000 and January 2001 at the German Antarctic research station Neumayer (70 degrees 39' S, 8 degrees 15' W). We report that mercury depletion events also occur in the Antarctic after polar sunrise and compare our measurements with a data setfrom Alert, Nunavut, Canada. We also present indications that BrO radicals and ozone play a key role in the boundary-layer chemistry during springtime mercury depletion events in the Antarctic troposphere. 相似文献