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151.
The electrical and gravimetric properties of langasite, La3Ga5SiO14, are related to its underlying defect and transport processes via previously developed predictive defect and transport models.
These models are used here to calculate the dependence of the partial ionic and electronic conductivities and the mass change
for langasite as functions of temperature, dopant type and level and pO2. Doping strategies devised for minimizing conductivity in langasite based on use conditions are described. For example, the
required dopant level to achieve minimum conductivity and thus minimum electrical losses in acceptor-doped langasite is shown
to depend on the operating pO2. Likewise intrinsic mass changes in langasite, dependent on dopant level, pO2 and temperatures, if high enough, can mask mass changes induced in active layers applied to langasite when used as a microbalance.
For example, the model predicts that the dopant level in donor-doped langasite has less of an impact on intrinsic mass change
due to external environmental changes when compared to acceptor-doped langasite. The models are also applied in defining acceptable
operating limits needed to achieve and/or the design of properties for desired levels of microbalance resolution and sensitivity. 相似文献
152.
Miltner Wolfgang H. R.; Krieschel Silke; Hecht Holger; Trippe Ralf; Weiss Thomas 《Canadian Metallurgical Quarterly》2004,4(4):323
Spider-phobic and nonphobic subjects searched for a feared/fear-relevant (spider) or neutral target (mushroom) presented in visual matrices of neutral objects (flowers). In half of the displays, the mushroom target was paired with a spider distractor, or a spider target was paired with a mushroom distractor. Although all subjects responded faster to the neutral target than to the feared/fear-relevant target, phobics were slower to respond than nonphobics when a mushroom target was presented with a spider distractor. Their eyes appeared to be drawn to the feared distractor before fixating neutral targets. A further experiment indicated no group differences when subjects merely judged the homogeneity of matrices. Thus, threat seems to capture the attention of phobics only when it is part of a background that subjects are explicitly instructed to ignore. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
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154.
Iron (III) oxide nanoparticles were synthesized inside the pore system of mesoporous carbon CMK-1. This intra-pore synthesis was carried out using several cycles of wet impregnation, drying and calcination procedures. The existence of iron (III) oxide nanoparticles within the pore system was proved by powder X-ray diffraction, nitrogen physisorption, preservation of the host structure by Raman spectroscopy and transmission electron microscopy. Finally, the local structure of the iron oxide was determined by X-ray absorption spectroscopy. 相似文献
155.
Michael Möller Ernst-Rüdiger Olderog Holger Rasch Heike Wehrheim 《Formal Aspects of Computing》2008,20(2):161-204
We describe how CSP-OZ, a formal method combining the process algebra CSP with the specification language Object-Z, can be
integrated into an object-oriented software engineering process employing the UML as a modelling and Java as an implementation
language. The benefit of this integration lies in the rigour of the formal method, which improves the precision of the constructed
models and opens up the possibility of (1) verifying properties of models in the early design phases, and (2) checking adherence
of implementations to models.
The envisaged application area of our approach is the design of distributed reactive systems. To this end, we propose a specific UML profile for reactive systems. The profile contains facilities for modelling components, their interfaces and interconnections via
synchronous/broadcast communication, and the overall architecture of a system. The integration with the formal method proceeds
by generating a significant part of the CSP-OZ specification from the initially developed UML model. The formal specification
is on the one hand the starting point for verifying properties of the model, for instance by using the FDR model checker. On the other hand, it is the basis for generating contracts for the final implementation. Contracts are written in the Java Modeling Language (JML) complemented by CSPjassda, an assertion language for specifying orderings between method invocations. A set of tools for runtime checking can be used
to supervise the adherence of the final Java implementation to the generated contracts.
This research was partially supported by the DFG project ForMooS (grants OL 98/3-2 and WE 2290/5-1).
C. B. Jones 相似文献
156.
Dirk Weuster-Botz Holger Paschold Bernd Striegel Holger Gieren Maria-Regina Kula Christian Wandrey 《化学工程与技术》1994,17(2):131-137
A continuous production process has been developed up to pilot scale (300 l) for FDH production with the methylotrophic yeast Candida boidinii. A high cell mass specific FDH activity (50 U/g) is achieved by process computer controlled supply of pure methanol to operate the reactor at an optimum methanol concentration of 10 g/l. The maximum FDH spacetime yield achievable with this process control involves a residence time of 7 h. The FDH space-time yield (STY) and FDH concentration are a function of the oxygen transfer rate (OTR) of the fermenter (maximum STY = 255 U/(l h) at kLa = 870 l/h). For a reasonable compromise between high FDH space-time yield and high FDH concentration, an optimum residence time is adjustable by regulating the supply of nutrient salt solution in relation to the OTR of the fermenter. On a pilot scale (200 l continuously stirred tank reactor) roughly 4 million U of FDH were produced within 10 days at a residence time of 14.3 h. Isolation of intracellular FDH enzyme was performed using extraction with an aqueous two-phase system (PEG/K2HPO4). A technical product quality of 1.2 U/mg FDH was achieved without any chromatographic purification step. 相似文献
157.
Detailed knowledge of the physical phenomena involved in subcooled boiling is of great importance for the design of liquid-cooled heat generating systems with high heat fluxes. Experimental heat transfer data were obtained for forced convective boiling of dichloro-difluoroethane (R 12). The flow is circulated upwards through a concentric annular vertical channel. The inner and outer diameters of the annulus are 0.016 m and 0.03 m respectively. The reduced pressures studied were 0.24 ≤ p/pcrit ≤ 0.8, inlet subcooling varied from 10 to 75 K and mass fluxes from 500 to 3000 kg/m2s, which corresponds to Re numbers from 30000 to 300000. The experiments, described in this study, demonstrate that liquid fluorocarbons show certain unusual boiling characteristics in the subcooled flow, such as hysteresis of the boiling curve. These characteristics are attributed to the properties of the fluid, mainly the Pr number and the very low surface tension. The pronounced boiling curve hysteresis can be explained by the fact that large nucleation sites may have been flooded prior to incipient boiling. A dimensionless regression formula is presented which predicts the onset of subcooled boiling as a function of reduced pressure (p/pcrit), Boiling-(Bo), Reynolds-(Re), and a modified Jacob number (Ja), over the whole range of parameters studied, with a good accuracy, including water data from literature. 相似文献
158.
159.