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排序方式: 共有177条查询结果,搜索用时 15 毫秒
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G. W. Franti J. C. Williams H. I. Aaronson 《Metallurgical and Materials Transactions A》1978,9(11):1641-1649
The mechanism of eutectoid decomposition in ten Ti-X binary systems, wherein X was successively Bi, Co, Cr, Cu, Fe, Mn, Ni,
Pb, Pd and Pt, has been investigated. In hypo-eutectoid alloys, the bainite reaction (defined in the present context as a
nonlamellar dispersion of intermetallic compound particles amongst proeutectoid a) predominated in all alloys studied but
Ti-Cu, where both bainite and pear lite were formed. In alloys of near eutectoid composition pearlite was the dominant product
in some systems and bainite was in others. These results are essentially independent of reaction temperature. They are quite
different from analogous ones in Fe-C alloys, where pearlite is the principal eutectoid structure formed at high temperatures
and bainite plays this role at low tem-peratures. The difference between the Ti-X and Fe-C behaviors was explained in terms
of the much more pronounced tendency for proeutectoid α plate formation in Ti-X than in Fe-C alloys and, on a theory due to
Hillert, of the need for disordered interphase boundaries in order to develop the cooperative growth mode that leads to the
evolution of pearlite. 相似文献
54.
Today, fibre-reinforced polymers (FRP) are widely used construction materials. The use of non-metallic reinforcement as inner reinforcement has many advantages, as is well known, but there are some areas of application that need to be resolved in order to improve the usage of FRP reinforcement in real-world conditions. One of these is the design of a suitable anchorage for prestressed FRP applications. It is difficult to design a safe anchorage using conventional methods of anchoring (systems for the anchorage of steel tendons) due to the well-known low compressive strength perpendicular to the fibres, this being due to the anisotropy of composite materials. Most of the anchoring systems commonly used worldwide are based on the use of metal parts (steel tubes, wedges, etc.) in a system which is primarily designed to be non-metallic. It is in contradiction with the initial intention to use non-metallic reinforcement. The presented text describes the basic physical and mechanical properties of a developed non-metallic anchor element. The essential principles of an analytical solution of the developed anchoring element based on the stiffness parameters of the system’s individual components are also presented. The behaviour of each material used is described in terms of simplify form. The functionality of the anchoring system was verified by a number of load tests and the obtained results were compared with theoretically and numerically calculated values. The presented results show the high efficiency of the anchoring system as well as the suitability of the derived analytical solution for simplified design and evaluation of the anchoring area. 相似文献
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Graphene: Thiofluorographene–Hydrophilic Graphene Derivative with Semiconducting and Genosensing Properties (Adv. Mater. 14/2015)
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58.
Raghvendra?Singh?YadavEmail author Jaromir?Havlica Ivo?Ku?itka Zuzana?Kozakova Martin?Palou Eva?Bartoní?ková Martin?Bohá? Franti?ka?Frajkorová Jiri?Masilko Miroslava?Hajdúchová Vojtěch?Enev Jaromir?Wasserbauer 《Journal of Superconductivity and Novel Magnetism》2015,28(4):1417-1423
In this paper, ZnFe2O4 spinel ferrite nanoparticles with different grain sizes at different annealing temperatures have been synthesized using the starch-assisted sol–gel auto-combustion method. The synthesized nanoparticles were characterized by conventional powder X-ray diffraction, Raman spectroscopy, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, and vibrating sample magnetometer. The X-ray diffraction (XRD) patterns demonstrated that the ZnFe2O4 nanoparticles consist of single-phase spinel structure with crystallite sizes 4.81, 8.72, 12.06, 29.32, and 72.60 nm annealed at 400, 600, 800, 1000, and 1200 °C, respectively. Field emission scanning electron microscopy reveals that particles are of spherical morphology at lower annealing temperature and hexagonal-like morphology at higher temperature. An infrared spectroscopy study shows the presence of two principal absorption bands in the frequency range around 525 cm?1 (ν 1) and around 350 cm?1 (ν 2), which indicate the presence of tetrahedral and octahedral group complexes, respectively, within the spinel ferrite nanoparticles. Raman spectroscopy study also indicated the change in octahedral and tetrahedral site-related Raman modes in zinc ferrite nanoparticles with change of particle size. The nanocrystalline ZnFe2O4 samples (4.81, 8.72, 12.06, 29.32 nm) show ferrimagnetic behavior, and bulk sample (72.60 nm) shows paramagnetic behavior. This change in magnetic behavior is due to change of cation distribution in ZnFe2O4 nanoparticles with decrease of particle size. 相似文献
59.
Buňková L Buňka F Pollaková E Podešvová T Dráb V 《International journal of food microbiology》2011,147(2):112-119
The aim of this work was to study, under model conditions, combined effects of the concentration of lactose (0-1% w/v), NaCl (0-2% w/v) and aero/anaerobiosis on the growth and tyramine production in 3 strains of Lactococcus lactis subsp. lactis and 2 strains of L. lactis subsp. cremoris. The levels of the factors tested were chosen with respect to the conditions which can occur during the real process of natural cheese production, including the culture temperature (10 ± 1 °C). In all strains tested, tyrosine decarboxylation was most influenced by NaCl concentration; the highest production of tyramine was obtained within the culture with the highest (2% w/v) salt concentration applied. Two of the strains L. lactis subsp. lactis produced tyramine only in broth with the highest NaCl concentration tested. In the remaining 3 strains of L. lactis, tyramine was detected under all conditions applied. The tested concentration of lactose and aero/anaerobiosis had a less significant effect on tyramine decarboxylation. However, it was also found that at the same concentrations of NaCl and lactose, a higher amount of tyramine was detected under anaerobic conditions. In all strains tested, tyramine decarboxylation started during the active growth phase of the cells. 相似文献
60.
Vinther TN Ribel U Pedersen TA Kjeldsen TB Jensen KJ Hubálek F 《Chembiochem : a European journal of chemical biology》2011,12(16):2448-2455
Chemical modifications of proteins are increasingly important in the development of protein drugs with fine-tuned properties. Regioselective modification, such as the chemoselective alkylation of an unpaired cysteine residue, is a prerequisite for obtaining homogenous protein products. The introduction of an unpaired Cys into the Cys-rich protein, insulin, was investigated by using a Cys scan. This was challenging as the introduced Cys could interfere with insulin's three existing disulfide bonds. However, eight insulin precursors were expressed in Saccharomyces cerevisiae with good yields. Although extensive post-translational modifications of the unpaired Cys were observed, the majority could be removed by selective reduction. An example Cys(7) insulin analogue was modified with a PEGylated maleimide moiety. The new variant was active in in vitro and in vivo models. Our results show that even small Cys-rich proteins can be expressed with additional unpaired Cys in meaningful yields and further chemically modified, while maintaining their biological activity. 相似文献