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51.
Kátia Gianni de Carvalho Lima Monika Francisca Kruger Jorge Behrens Maria Teresa Destro Mariza Landgraf Bernadette Dora Gombossy de Melo Franco 《LWT》2009,42(2):491-193
The study compared the growth capability of probiotic (Lactobacillus acidophilus La05, Lactobacillus casei Lc01 and Bifidobacterium animalis Bb12) and non-probiotic (Lactobacillus delbrueckii subsp bulgaricus and Streptococcus thermophilus) cultures on twenty-one culture media grouped according to selectivity: non-selective agars, selective agars without antibiotics and MRS agars containing different combinations of lithium chloride, cystein, bile salts and antibiotics. Four of these media were selected for quantitative enumeration of L. acidophilus La05, L. casei Lc01, and B. animalis Bb12. The best culture media and incubation conditions for enumeration of the probiotic cultures were: B. animalis: MRS agar with dicloxacillin, 37 °C or 42 °C, anaerobiosis; L. acidophilus: MRS agar with bile salts, 37 °C or 42 °C, aerobiosis; L. casei: MRS agar with lithium chloride and sodium propionate, 37 °C or 42 °C, aerobiosis or anaerobiosis. Plating on MRS with glucose replaced by maltose, 37 °C or 42 °C, anaerobiosis, will distinguish probiotic from non-probiotic cultures. For enumeration of each probiotic in a mixed culture, the following media and incubation conditions were recommended: B. animalis: 4ABC-MRS, 42 °C, anaerobiosis, L. acidophilus: LC medium, 42 °C, aerobiosis or anaerobiosis and L. casei: LP-MRS, 42 °C, aerobiosis or anaerobiosis. In all experiments, differences in counts using pour plating or surface plating were not significant (P ≤ 0.05). 相似文献
52.
Teshome B. Yisgedu Zhenguo Huang Xuenian Chen Hima K. Lingam Graham King Aaron Highley Sean Maharrey Patrick M. Woodward Richard Behrens Sheldon G. Shore Ji-Cheng Zhao 《International Journal of Hydrogen Energy》2012
The structure of (NH4)2B10H10 (1) was determined through powder XRD analysis. The thermal decomposition of 1 and (NH4)2B12H12 (2) was examined between 20 and 1000 °C using STMBMS methods. Between 200 and 400 °C a mixture of NH3 and H2 evolves from both compounds; above 400 °C only H2 evolves. The dihydrogen bonding interaction in 1 is much stronger than that in 2. The stronger dihydrogen bond in 1 resulted in a significant reduction by up to 60 °C, but with a corresponding 25% decrease in the yield of H2 in the lower temperature region and a doubling of the yield of NH3. The decomposition of 1 follows a lower temperature exothermic reaction pathway that yields substantially more NH3 than the higher temperature endothermic pathway of 2. Heating of 1 at 250 °C resulted in partial conversion of B10H102− to B12H122−. Both 1 and 2 form an insoluble polymeric material after decomposition. The elements of the reaction network that control the release of H2 from the B10H102− can be altered by conducting the experiment under conditions in which pressures of NH3 and H2 are either near, or away from, their equilibrium values. 相似文献
53.
Daniela Hesse Muhammad Badar André Bleich Anna Smoczek Silke Glage Marc Kieke Peter Behrens Peter Paul Müller Karl-Heinz Esser Martin Stieve Nils Kristian Prenzler 《Journal of materials science. Materials in medicine》2013,24(1):129-136
Chronic otitis media is a common disease often accompanied by recurrent bacterial infections. These may lead to the destruction of the middle ear bones such that prostheses have to be implanted to restore sound transmission. Surface coatings with layered double hydroxides (LDHs) are evaluated here as a possibility for drug delivery systems with convenient advantages such as low cytotoxicity and easy synthesis. Male New Zealand White rabbits were implanted with Bioverit® II middle ear prostheses coated with the LDH Mg4Al2(OH)12(SO4)2·6H2O impregnated with ciprofloxacin. 12 (group 1) were directly infected with Pseudomonas aeruginosa and another 12 (group 2) 1 week after the implantation. Clinical outcome, blood counts, histological analyses and microbiological examination showed an excellent antimicrobial activity for group 1, whereas this effect was attenuated in animals where infection was performed 1 week after implantation. This is the first study to demonstrate an efficient drug delivery system with an LDH coating on prostheses in the middle ear. 相似文献
54.
The acoustic emission technique is a very promising non-destructive and online capable approach for the detection of damage events in metal forming processes. The feasibility of using this testing method for online monitoring of cold forging processes of the case hardening steel 1.7321 (20MoCr4) was experimentally proven. In this paper, exemplary upsetting tests under varying test conditions were continuously monitored to analyze the relationship between cracking and resulting AE as well as to determine ideal AE measuring parameters. Finally, the critical forming stage of an industrial cold forging process for manufacturing of drive bevel gears is examined by applying acoustic emission technique. Cracking and tool wear were detected by analyzing the distribution of the AE parameters energy, hits and amplitude over the forming process. 相似文献
55.
Conrad F Massue C Kühl S Kunkes E Girgsdies F Kasatkin I Zhang B Friedrich M Luo Y Armbrüster M Patzke GR Behrens M 《Nanoscale》2012,4(6):2018-2028
Nanostructured Cu(x)Zn(1-x)Al(2)O(4) with a Cu:Zn ratio of ?:? has been prepared by a microwave-assisted hydrothermal synthesis at 150 °C and used as a precursor for Cu/ZnO/Al(2)O(3)-based catalysts. The spinel nanoparticles exhibit an average size of approximately 5 nm and a high specific surface area (above 250 m(2) g(-1)). Cu nanoparticles of an average size of 3.3 nm can be formed by reduction of the spinel precursor in hydrogen and the accessible metallic Cu(0) surface area of the reduced catalyst was 8 m(2) g(-1). The catalytic performance of the material in CO(2) hydrogenation and methanol steam reforming was compared with conventionally prepared Cu/ZnO/Al(2)O(3) reference catalysts. The observed lower performance of the spinel-based samples is attributed to a lack of synergetic interaction of the Cu nanoparticles with ZnO due to the incorporation of Zn(2+) in the stable spinel lattice. Despite its lower performance, however, the nanostructured nature of the spinel catalyst was stable after thermal treatment up to 500 °C in contrast to other Cu-based catalysts. Furthermore, a large fraction of the re-oxidized copper migrates back into the spinel upon calcination of the reduced catalyst, thereby enabling a regeneration of sintered catalysts after prolonged usage at high temperatures. Similarly prepared samples with Ga instead of Al exhibit a more crystalline catalyst with a spinel particle size around 20 nm. The slightly decreased Cu(0) surface area of 3.2 m(2) g(-1) due to less copper incorporation is not a significant drawback for the methanol steam reforming. 相似文献
56.
Streams in North Rhine‐Westphalia (Germany) are frequently impacted by hydromorphological degradation leading to a loss of sensitive species and a reduction in diversity. These findings mean that the final objective of the European Water Framework Directive to achieve the good ecological status will be failed for a large number of streams. In a holistic approach, a new concept, considering the cost efficiency, has been developed to enhance habitats by morphological changes. This guide serves as a basis for stream restoration projects. The theoretical background is that near‐natural sections influence adjacent sections of medium habitat quality positively by migration of type‐specific sensitive organisms. The preconditions are a local taxa richness in the catchment area, the reduction of nutrients and organic matter, and the guarantee of free movement. This so‐called ‘spreading effect’ can be measured upstream and downstream. The length of by these means valourized sections depends on the stream type and on the biological quality component. 相似文献
57.
Silvia F. Moya Ruth L. Martins Antje Ota Edward L. Kunkes Malte Behrens Martin Schmal 《Applied Catalysis A: General》2012
The Pd on α-Al2O3 catalysts with Pd particles in the low nanometer range have been prepared by a sonochemical reduction and a colloidal method, respectively. The two catalysts differ in their particle size, the widths of their particle size distributions and the amount of carbon incorporation in the Pd lattice.The adsorptive properties of the Pd/Al2O3 samples are different as a result of the different preparation methods. The methane adsorption capacity of that sample with smaller particles is lower than that of the catalyst with larger particles and the energy of activation is nearly doubled. DRIFTS and TPD results of CO adsorption supported by transmission electron microscopy data indicate that the PdSON catalyst with smaller and more homogeneous particles than PdCOL is highly dispersed which influences the coupling-hydrogenolysis process.The catalytic activity evidenced the formation of different adspecies during methane coupling and chemisorption on both catalysts. During the hydrogenation the carbon adspecies formed mainly methane at low adsorption temperatures. The significant amount of adsorbed methane at 773 K is governed by the highly active coordination unsaturated sites at the surface. 相似文献
58.
In times of increasing energy costs automotive light weight construction is gaining more importance. The production of hybrid compounds by forging is a promising method to successfully manufacture functional parts by applying resource‐saving process steps. However, in compound forging of steel‐aluminum parts shrinking gaps may form because of the different thermal expansion coefficients. To avoid these unwanted gaps, it is necessary to achieve a firmly bonded joint e.g. by intermetallic phases. This paper deals with the investigation of the influences of different sample preparations, process parameters and true strains on the formation of intermetallic phases. Thus, the optimum production parameters for compound forging of steel‐aluminum parts will be determined. 相似文献
59.
60.
Falk Heinroth Simon Münzer Armin Feldhoff Sven Passinger Wei Cheng Carsten Reinhardt Boris Chichkov Peter Behrens 《Journal of Materials Science》2009,44(24):6490-6497
In this work, the preparation of three-dimensional hierarchical pore structures by a combination of laser-based templates
and the self-organization process of mesostructured titania is presented. For this purpose macrostructured polymers produced
by two-photon polymerization act as a template for the deposition of a mesostructured titania film from a solution containing
an amphiphilic block copolymer by dip coating. A carefully applied calcination procedure removes both the macrotemplating
polymer and the mesotemplating surfactant molecules so that a replica of the initial polymer structure with a hierarchical
(macro- and meso-) pore system is obtained. In addition, the titania, which is amorphous after deposition, is transferred
into crystalline anatase during calcination. Materials with dual pore systems are interesting for possible applications in
catalysis and sorption, and three-dimensional crystalline structures from materials with high refraction index are attractive
for photonic applications, for example as photonic crystals. 相似文献