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排序方式: 共有1615条查询结果,搜索用时 23 毫秒
71.
Characterization of Biomimetic Cofactors According to Stability,Redox Potentials,and Enzymatic Conversion by NADH Oxidase from Lactobacillus pentosus 下载免费PDF全文
Claudia Nowak André Pick Dr. Lénárd‐István Csepei Prof. Dr. Volker Sieber 《Chembiochem : a European journal of chemical biology》2017,18(19):1944-1949
Oxidoreductases are attractive biocatalysts that convert achiral substrates into products of higher value, but they are also for the most part dependent on nicotinamide cofactors. Recently, biomimetic nicotinamide derivatives have received attention as less costly alternatives to natural cofactors. However, recycling of biomimetics is still challenging because there are only limited opportunities. Here, we have characterized various biomimetic cofactors with regard to stability and redox potentials to find the best alternative to natural cofactors. Further, the cofactor spectrum of NADH oxidase from Lactobacillus pentosus (LpNox) could be expanded, and the enzymatic activity was also compared to activities with different small‐molecule catalysts. As a result, we succeeded in identifying several strategies for regeneration of oxidized biomimetics. 相似文献
72.
Kinetic study of hydrogen peroxide decomposition at high temperatures and concentrations in two capillary microreactors 下载免费PDF全文
Minjing Shang Timothy Noël Yuanhai Su Volker Hessel 《American Institute of Chemical Engineers》2017,63(2):689-697
On the background of the direct adipic acid synthesis from cyclohexene and H2O2, a kinetic model was derived for the H2O2 decomposition catalyzed by sodium tungstate at high H2O2 concentrations and high temperatures. A perfluoroalkoxy (PFA) and a stainless steel micro‐flow capillary match commonly used microreactor materials. In the PFA capillary, the decomposition of hydrogen peroxide increased with residence time, reaction temperature and catalyst loading. The reaction order with respect to hydrogen peroxide and sodium tungstate was zero and one, respectively. Simulated data fit well with experimental data in the PFA capillary. While showing a similar trend as that in the PFA capillary, the stainless steel capillary exhibited much higher reaction rates. The steel surface participated in the decomposition process as a heterogeneous catalyst. Key influencing factors of the H2O2 decomposition provided some clues on the reaction mechanism of the adipic acid synthesis and its process optimization. © 2016 American Institute of Chemical Engineers AIChE J, 63: 689–697, 2017 相似文献
73.
Tikole S Jaravine V Rogov VV Rozenknop A Schmöe K Löhr F Dötsch V Güntert P 《Chembiochem : a European journal of chemical biology》2012,13(7):964-967
Faster than death: NMR techniques that make use of nonlinear sampling and hyperdimensional processing enable the recording of complete NMR data sets for the automated assignment of the backbone and side-chain resonances of short-lived protein samples of cell lysates. 相似文献
74.
Jacobsen V Tätte T Branscheid R Mäeorg U Saal K Kink I Lõhmus A Kreiter M 《Ultramicroscopy》2005,104(1):39-45
We demonstrate that an optically transparent and electrically conductive antimon-doped tin-oxide tip that is prepared in a sol-gel process can be used as a probe for scanning tunnelling microscopy (STM), yielding atomic vertical and nanometre lateral resolution. Emission of visible light from the tunnelling junction between gold particles and the tip is observed for bias voltages above 7 V. In contrast to the metallic tips generally used in STM, this tip does not significantly perturb the local optical response. Therefore, the tunnelling induced light can be used to map the optical near-field of surface structures with the tunnel gap acting as highly localised light source for the investigation of near-field enhancement in complex metal structures. 相似文献
75.
Oil-in-water(o/w) emulsions were produced with a membrane emulsification system. The effect of the continuous phase viscosity on the emulsification was studied. The theoretical analyses show that the continuous phase viscosity influences not only the flow field of the continuous phase but also the interfacial tension. The droplet size distribution and disperse phase flux for different continuous phase viscosity were investigated experimentally at constant wall shear stress and constant volume flow rate of the continuous phase respectively. 相似文献
76.
77.
Martin Hintersteiner Dr. Thierry Kimmerlin Dr. Geraldine Garavel Dr. Thorsten Schindler Dr. Roman Bauer Dr. Nicole‐Claudia Meisner Dr. Jan‐Marcus Seifert Dr. Volker Uhl Dr. Manfred Auer Prof. Dr. 《Chembiochem : a European journal of chemical biology》2009,10(6):994-998
New and improved : The incorporation of a 6‐chlorotryptophan (6‐Cl‐Trp) into a β‐peptide (M)‐314 helix leads to a high‐affinity hDM2 inhibitor, as demonstrated by fluorescence fluctuation analysis at single molecule resolution. When conjugated to penetratin, the newly derived hDM2 binder specifically inhibits tumour cell growth in vitro.
78.
Kerstin Hannemann Volker Puchta Ernst Simon Herta Ziegler Gunter Ziegler Gerhard Spiteller 《Lipids》1989,24(4):296-298
The observation that F-acids (1) occur in rat chow initiated a search for F-acids in human diet. We observed that the amount
of F-acids with a pentyl side chain in α-position taken up with a one-day diet correlates well with the amount of excreted
degradation products, the pentyl urofuran acids (2), (3) and (4). Therefore it can be concluded that F-acids with a pentyl
side chain are not produced in the human body but are introduced through the diet. The origin of F-acids carrying an α-propyl
side chain is less clear. The amount of propyl-urofuran acids (2) and (3) excreted in urine was found in one case out of three
to be five times higher than the amount of F-acids carrying a propyl group in α-position taken up by the diet. Therefore,
it can presently not be excluded that a portion of the propyl F-acids is produced by the body.
F-acids found in human food are mainly introduced into the body by vegetables and fruits. F-acids were found also in birch
leaves in considerable amounts, as well as in grasses, dandelion and clover leaves. Thus, we can conclude that F-acids are
common constituents of plants. 相似文献
79.
Ulrich Semmler Michael Bräunig Welf-Guntram Drossel Gerhard Schmidt Volker Wittstock 《Production Engineering》2014,8(4):543-550
Challenges for machining include greater and greater material removal rates coupled with an increase in the use of difficult to machine materials, as well as environmental-friendly dry or minimum quantity lubrication machining, small manufacturing batches and frequently changed manufacturing orders. These trends are accompanied by high temperatures in the machining process and large, variable heat flows causing thermo-elastic displacements of the tool, the workpiece and the clamping devices. Although the displacements are small, in the range of a few micrometers, they have assumed more and more importance because of growing requirements for manufacturing accuracy. Thermo-elastic displacements of the tool due to heat flow during machining are investigated and analysed in this paper. Temperatures and displacements are measured on a test bed equipped with measuring instruments. The identification of the thermal boundary and contact conditions is supported by finite element models. Knowledge of the heat flows resulting from the machining process is a prerequisite for control of and compensation for displacements. Since these heat flows either cannot be measured or can only be measured with enormous effort, heat flows are determined by means of numerical simulation of the machining process itself. This strategy has been previously used as a systematic approach for turning in orthogonal cutting conditions. However, further investigations are needed for oblique turning conditions, milling and drilling operations. 相似文献
80.
Elnaz Shahbazali Emilie M. F. Billaud Arash Sarhangi Fard Jan Meuldijk Guy Bormans Timothy Noel Volker Hessel 《American Institute of Chemical Engineers》2021,67(1):e17067
Liquid-phase adsorption has hardly been established in micro-flow, although this constitutes an industrially vital method for product separation. A micro-flow UV-photo isomerization process converts cis-cyclooctene partly into trans-cyclooctene, leaving an isomeric mixture. Trans-cyclooctene adsorption and thus separation was achieved in a fixed-bed micro-flow reactor, packed with AgNO3/SiO2 powder, while the cis-isomer stays in the flow. The closed-loop recycling-flow has been presented as systemic approach to enrich the trans-cyclooctene from its cis-isomer. In-flow adsorption in recycling-mode has hardly been reported so that a full theoretical study has been conducted. This insight is used to evaluate three process design options to reach an optimum yield of trans-cyclooctene. These differ firstly in the variation of the individual residence times in the reactor and separator, the additional process option of refreshing the adsorption column under use, and the periodicity of the recycle flow. 相似文献