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排序方式: 共有695条查询结果,搜索用时 15 毫秒
661.
K. Hoppe 《Molecular nutrition & food research》1990,34(10):968-968
662.
"Sixty-five Ss were given eight nonsense words to learn. Forty-two of the Ss learned the task in groups of three, and the remaining 23 learned the task as individuals… . The data indicate that a concept of group facilitation need not be introduced to explain the groups' performance." (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
663.
664.
K. Hoppe 《Molecular nutrition & food research》1994,38(3):283-294
Contributions to the psychophysics of sweet taste. Part 5. Investigations of the use of a sequential staircase-method for the determination of equal intense pairs of stimuli The suitability of a sequential staircase-method for the determination of equal stimuli of the gustatory sense is experimentally investigated. The aim is the decrease of experimental expenditure when ruling sources of bias. In order to realize them sucrose solutions are used both for the constant stimulus and also for the sequence of stimuli. Possible factors are the gradation of the sequence of stimuli and its displacement towards the constant stimulus. These are factorized in a two-staged trial arrangement and are interpreted in a form of an analysis of variance. The gradation of sequence (grain) is the key factor. It defines both the occasional bias and also the efficiency of systematical sources of bias. Thus the subject-depending judgement errors, which occur in larger gradation, are avoidable with their adjustment on the half of the difference threshold. The errors, which are due to the direction, are counterbalanced through an up and down trial execution with a following meaning average. A remaining influence of the displacement of sequence is normally neglective. The standard deviation for the single determination lies - independently of the concentration level - dimensionally slightly above the half of the setting grain. The method of constant stimuli requires at least the twofold experimental expenditure for a simular result. 相似文献
665.
666.
Jiri Hoppe 《Software》1986,16(12):1109-1116
A new method for the implementation of synchronization primitives is described. The method combines the flexibility of user defined primitives with the possibility of compiler checks. The method allows the tailoring of the size and of the performance of the synchronization primitives to the needs of the user. 相似文献
667.
668.
Walther Hoppe 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1971,147(1):14-20
Zusammentassung Spezifische Zusammensetzung und Hydrolysenbedingungen sind von entscheidender Bedeutung für vergleichende Aminosäureanalysen in biologischem Material. Bei gleichen Proben ist mit einer standardisierten Methode eine Reproduzierbarkeit von etwa ±3% möglich, extreme Unterschiede in der Zusammensetzung führen aber zu verschiedenen Werten. So verursachen Kohlenhydrate erhebliche Verluste, die sich auf die einzelnen Aminosäuren sehr unterschiedlich verteilen. Hydrolyse mit Phenolzusatz bringt keine generelle Verbesserung. Analysenkontrolle mit Testsubstanzen sowie Differenzanalyse bei sehr geringen und unterschiedlichen Aminosäurenmengen verbessern die Analysentechnik. Die proteinfreie Stickstoff-Fraktion ermittelt aus dem Aminosäurenspektrum und Kjeldahl-Stickstoff betrug bei Hefen 4,7–14,1%. Die Konzentration der freien (Pool) und strukturgebundenen (Protein) Aminosäuren veränderte sich beim Waehstum der Hefen, bei Belüftung im Wasser (Verarmung) erfolgte nur bei den freien Aminosäuren eine Konzentrationsänderung.
Herrn Professor Dr. H. Simon möchte ich für sein besonderes Interesse und die Förderung meiner Arbeit herzlich danken. 相似文献
Amino acid analysis in biological materials I. Influence of hydrolysis, carbohydrates and purin basis
Summary The specific composition and the condition of hydrolysis are very important for the comparative amino acid analysis of biological material. Wide differences in the composition of the biological material will give different results, the reproductivity with the standardized method with equal samples ranges within ± 3%. Carbohydrates for example cause a loss which is different with each amino acid. There is no improvement by addition of Phenol. Test substances as a controll of the analysis as well as difference analysis improve the analytical technique, when the sample contains some of the amino acids in very small amounts. The protein free fraction of yeasts was 4,7–14,1% when estimated by the amino acid spektrum and Kjeldahl nitrogen. There was a change in the composition of the amino acids in the pool and in the protein during growth of the yeast. Prolarged airation changes the concentration of the free amino acid pool only.
Herrn Professor Dr. H. Simon möchte ich für sein besonderes Interesse und die Förderung meiner Arbeit herzlich danken. 相似文献
669.
Numerical simulation of piezoelectrically agitated surface acoustic waves on microfluidic biochips 总被引:1,自引:0,他引:1
Andreas Gantner Ronald H. W. Hoppe Daniel Köster Kunibert Siebert Achim Wixforth 《Computing and Visualization in Science》2007,10(3):145-161
Microfluidic biochips are biochemical laboratories on the microscale that are used for genotyping and sequencing in genomics,
protein profiling in proteomics, and cytometry in cell analysis. There are basically two classes of such biochips: active
devices, where the solute transport on a network of channels on the chip surface is realized by external forces, and passive
chips, where this is done using a specific design of the geometry of the channel network. Among the active biochips, current
interest focuses on devices whose operational principle is based on piezoelectrically driven surface acoustic waves (SAWs)
generated by interdigital transducers placed on the chip surface. In this paper, we are concerned with the numerical simulation
of such piezoelectrically agitated SAWs relying on a mathematical model that describes the coupling of the underlying piezoelectric
and elastomechanical phenomena. Since the interdigital transducers usually operate at a fixed frequency, we focus on the time-harmonic
case. Its variational formulation gives rise to a generalized saddle point problem for which a Fredholm alternative is shown
to hold true. The discretization of the time-harmonic surface acoustic wave equations is taken care of by continuous, piecewise
polynomial finite elements with respect to a nested hierarchy of simplicial triangulations of the computational domain. The
resulting algebraic saddle point problems are solved by blockdiagonally preconditioned iterative solvers with preconditioners
of BPX-type. Numerical results are given both for a test problem documenting the performance of the iterative solution process
and for a realistic SAW device illustrating the properties of SAW propagation on piezoelectric materials.
The first two authors have been supported by the DFG within the Collaborative Research Center SFB 438. The seond author acknowledges
further support by the NSF under Grant No. DMS-0411403, Grant No. DMS-0412267 and Grant-No. DMS-0511611. 相似文献
670.
Alejandra Lara Adrien Létoffé Sandrine Hoppe Maxime Mourer Christian G'sell Jean-Bernard Regnouf-de-Vains Marc Ponçot 《应用聚合物科学杂志》2021,138(8):49889
An isotactic polypropylene grafted by 1 wt% of maleic anhydride (iPP-g-MAH) was chemically modified to provide it with new functional abilities and improved mechanical properties. The specific additive considered in this work is a derivative of bis(aminoalkyl)-calix[4]arene. Not only this molecule serves as a cross-linking agent, but it offers grafting sites for metallic ions that confer electrolytic conductivity to the initially insulating polyolefin. Materials were synthesized by reactive extrusion, and subsequently manufactured as plates by injection molding. The three-dimensional macromolecular architecture was optimized by adjusting the NH2:MAH molar ratio in a range from 0.5:1 to 1:1. Fourier transform infrared spectroscopy revealed the amine/ anhydride chemical reactions, while gel content measurements were used to determine the degree of cross-linking. The crystalline microstructure of the different materials was characterized by two complementary methods: (a) overall crystallinity by differential scanning calorimetry; (b) lamellar thickness by thermal fractionation using the self-successive auto-nucleation procedure. Only a small decrease of the crystalline lamellae is observed. The mechanical properties were determined by a video-controlled tensile testing method and by Brillouin spectroscopy. A transition from brittle to ductile behavior was observed for increasing cross-links density. Scanning electron microscopy on fracture surfaces showed that ductile fracture was favored by the development of fibrils. 相似文献