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排序方式: 共有433条查询结果,搜索用时 187 毫秒
61.
62.
ASME法规规定了锅炉和压力容器产品受压元件的设计、制造、检验方面的要求。舳法规中关于水压试验的有关规定,需要企业在具体检验中细化。在水压试验和气压试验中,目视检验是经常使用的检验方法,在产品生产过程的检查中,目视检验同样是重要的检验方法。 相似文献
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Submarine pipelines are deemed as thin-walled structures in which relative external pressure may be created in some cases of fluid transmission. The certain effect of this type of loading is local buckling and its propagation along the considerable length of the line. In this study, an experimental program has been performed, in which the influence of ring stiffeners on the buckling strength of pipelines is investigated. In the tests, only hydrostatic pressure is considered as the major loading case, and the effect of further loads is neglected. The modes of initial buckling, buckling propagation, postbuckling, and development of yield lines and the final collapse of the pipeline have been closely appraised. It is verified that the buckling threshold highly hikes up by attaching some light ring stiffeners. By decreasing the ring spacing, the difference between buckling and failure loads is diminished and torsion-type yield lines at failure mode occur on the pipe skin. 相似文献
65.
Heekyu Choi Ochirhuyag Bayanjargal JunIchiro Tsubaki Takamasa Mori Tadamitsu Sugimoto JungEun Lee 《Korean Journal of Chemical Engineering》2008,25(5):1165-1169
A cake-less continuous filtration equipment has been developed based on an evaluation of inorganic powder slurry characteristics
by many kinds of measurement methods, such as a sedimentation test under gravity and a hydrostatic pressure test. We have
been developing a high-performance cake-less filtration system in which a condensed inorganic powder slurry layer maintains
its fluidity. The development of this novel filtration system has allowed us to cease the scraping operation of the cake as
well as to collect the highly condensed slurry more easily. These results clearly show that a new device may be realized for
the deposition of highly condensed, fluid slurries. It is confirmed that the concentration of the condensed slurry amounted
to 35 vol% while still retaining fluidity. The specifications of our new filtration system and its operation conditions for
scale-up can be determined by theoretical methods. There is good potential for successfully collecting high condensation slurry
more easily in a multiple filter system. 相似文献
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Stefan Kasapis 《Food Hydrocolloids》2012,26(2):464-472
It has been demonstrated that industrial polysaccharides (agarose, deacylated gellan and κ-carrageenan) form networks of reduced enthalpic content in the presence of high levels of non-crystallizing co-solute (e.g., glucose syrup) that exhibit time-temperature dependent behaviour of a typical rubberlike polymer. In contrast, amylose holds its structural characteristics unaltered and does not reach a state of molecular mixing with glucose syrup, with morphological features being those of a micro phase-separated mixture. Variation in phase morphology and density of intermolecular associations leads to entropic or enthalpic viscoelasticity in systems, and it was utilised to define distinct classes of food related biomaterials exhibiting an extensive glass transition region or absence of vitrification phenomena. The approach was extended to encompass the experimental parameters of a porous matrix and the application of hydrostatic pressure. In the former, work discusses discrepancies in the Tg - porosity relationship attributable to the different extent to which the two techniques of calorimetry and mechanical spectroscopy respond to degrees of molecular mobility. In the latter, it was shown that the time-temperature-pressure equivalence of synthetic amorphous polymers is not operational in the glass-like behaviour of high sugar systems in the presence of gelatin or gelling polysaccharides. The existing body of evidence allowed quantitative treatment of results based on the asymmetric distribution theory of molecular relaxation time that identifies the chemical fingerprint of the local motions operating at the vicinity of Tg. Furthermore, the diffusional mobility of a bioactive compound within a glassy matrix could be followed in relation to temperature induced changes in free volume using the time-temperature superposition principle. 相似文献
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《Petroleum Science and Technology》2013,31(7-8):927-942
Abstract Preliminary studies of the effect of pressure on a system composed of 32 asphaltene molecules immersed in a solvent (pentane or toluene) were carried out. In this case, this system was randomly distributed into a cubic box of 49430.9 Å3 of volume. The NPT simulations showed spontaneous asphaltene disassociation when an asphaltene aggregate was immersed in toluene as a function of the pressure. Among the main configurations found, offset π-stacked geometry was the most frequently observed stacking form. Calculation of the radial distribution function on the system also revealed that the nearest asphaltene molecules have an average separation distance around 3.8 Å. This is a value in agreement with the classical model for asphaltene aggregates developed almost 40 years ago. Some possible asphaltene micelle formation and phase transitions will be described. 相似文献
70.
Muditha Dissanayake Stefan Kasapis Paul George Benu Adhikari Martin Palmer Barbara Meurer 《Food Hydrocolloids》2013
Hydrostatic pressure effects on whey protein/lactose mixtures were recorded with subsequent analysis of their structural, molecular and glass transition properties in comparison to thermal effects at atmospheric pressure. Experimental techniques used were small deformation dynamic oscillation in shear, modulated differential scanning calorimetry, Fourier transform infrared spectroscopy, and theoretical modelling of glass transition phenomena. Levels of solids ranged from 30 to 80% (w/w) in formulations with a protein/co-solute ratio of four-to-one. Addition of lactose protects the secondary conformation of the protein under application of high hydrostatic pressure. Nevertheless, pressurized protein systems are able to form three-dimensional structures due to the reduction in polymeric free volume and the development of an efficient friction coefficient amongst tightly packed particles. Systems can be seen as developing a “molten globular state”, where the structural knots of pressure-treated networks remain in the native conformation but achieve intermolecular cross-linking owing to frictional contact. Furthermore, pressure treated assemblies of condensed whey protein preparations could match the viscoelasticity of the thermally treated counterparts upon cooling below ambient temperatures. That allowed examination of the physical state and morphology of a condensed preparation at 80% solids by the combined framework of reduced variables and free volume theory thus affording derivation of glass transition temperatures for pressurized and atmospheric samples. 相似文献