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排序方式: 共有544条查询结果,搜索用时 15 毫秒
91.
As a piezoelectric application of a ferroelectric material of layer-structure type, a surface acoustic wave device using a ceramic Pb0.15 (NaBi)0.425Bi4Ti4O15, produced by a hot-forging technique is described. The surface acoustic wave on the substrate with the poling axis parallel to the free surface is Blustein-Gulyaev type and its velocity is 2812 m/s. 相似文献
92.
ABSTRACTMode conversion between higher-order modes is attained in a step-index four mode fibre using an in-line polarization controller followed by a force-induced long period fibre grating. By adjusting the field orientation of the LP11 mode to the antisymmetric fibre grating, the LP11 mode is converted to the LP21 mode with a spatially periodic force of 50 N along the fibre length of 50?mm. The mode conversion is evaluated by observing the far-field and near-field patterns of the fibre output and by comparing the transmitted optical power with and without the additional two-mode fibre. The phase-matching grating period is required of the accuracy of roughly ±5?μm and the radiation loss during the mode conversion is as low as 0.01?dB. 相似文献
93.
The structure of the L-tartaric acid adsorbed on the surface of a nickel metal catalyst with or without NaBr was studied by FT-IRAS. The carboxylic acid and carboxylate type adsorbed species were observed on nickel surface which was treated with only tartaric acid, while only one type of carboxylate ion was observed on the nickel surface which was treated with tartaric acid and NaBr. 相似文献
94.
Masahiro Endo Yasuyuki Morishima Shinichi Yano Kenji Tadano Yukinobu Murata Kenji Tsunashima 《应用聚合物科学杂志》2006,101(6):3971-3978
Miscibility was studied for four polyamide blends of 6I/6T [copolymer consisting of 1,6‐hexamethylene diamine and isophthalic acid (6I) (70 wt %) and terephthalic acid (6T) (30 wt %)] with MXD6 (polyamide of m‐xylenediamine and adipic acid), BAC6 (polyamide of 1,3‐bis(aminomethyl)cyclohexane and adipic acid), TR55 (copolymer consisting of nylon 11 (30 wt %), and polyamide of bis(3‐methyl, 4‐aminocyclohexyl)methane (30 wt %) and isophthalic acid (70 wt %), and CX7323 (polyamide of bis(4‐aminocyclohexyl)methane and dodecanedicarboxylic acid), using differential scanning calorimetry, X‐ray diffraction method, and electronmicroscopic observation. In quenched MXD6/(6I/6T) and BAC6/(6I/6T) blends, MXD6 and BAC6 components were miscible to 6I/6T, but TR55 and CX7323 components were completely phase‐separated from 6I/6T. Interestingly on electronmicroscopic observations, TR55 and CX7323 components were seen as droplets in 6I/6T medium when the content is low, but when 50 wt %, a layered structure was constructed with 6I/6T, reminiscent of morphological structure in block copolymer. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3971–3978, 2006 相似文献
95.
The thermoplasticization of thiolignin (TL) and dioxane lignin (DL) with various synthetic plasticizers has been investigated. The thermal softening temperatures Ts of the lignin–plasticizer systems were measured applying the flow tester technique which is useful for investigating the thermal properties of polymers. It was found that the Ts of the lignins were lowered considerably as the solubility parameters (after Hildebrand) of the plasticizers approach close to that of lignin, namely, around 11. The lowering in the Ts of the lignins with the plasticizers was described by a linear equation with respect to the plasticizer concentration which ranged up to 20 wt-%. The sorption of the limited amounts (< 5%) of water to the lignins also considerably decreased the Ts, however, the extent of lowering in the Ts by water sorption is less than that by the plasticizer addition at their contents over about 15%. The relationship of Ts to water content (up to about 30%) was curved, not linear. It was clearly shown that a combined use of the plasticizer and water brought about the most effective plasticizing for the lignins compared with the use of either of those alone. 相似文献
96.
Satoshi Hiroi Seongho Choi Shunsuke Nishino Okkyun Seo Yanna Chen Osami Sakata Tsunehiro Takeuchi 《Journal of Electronic Materials》2018,47(6):3113-3118
To gain deep insight into the mechanism of phonon scattering at grain boundaries, we investigated the boundary thermal resistance by using picosecond pulsed-laser time-domain thermoreflectance for epitaxially grown W/Fe2VAl/W films. By using radio-frequency magnetron sputtering, we prepared a series of the three-layer films whose Fe2VAl thickness ranged from 1 nm to 37 nm. The fine oscillation of reflectivity associated with the top W layer clearly appeared in synchrotron x-ray reflectivity measurements, indicating a less obvious mixture of elements at the boundary. The areal heat diffusion time, obtained from the time-domain thermoreflectance signal in the rear-heating front-detection configuration, reduced rapidly in samples whose Fe2VAl layer was thinner than 15 nm. The ~ 10% mismatch in lattice constant between Fe2VAl and W naturally produced the randomly distributed lattice stress near the boundary, causing an effective increase of boundary thermal resistance in the thick samples, but the stress became homogeneous in the thinner layers, which reduced the scattering probability of phonons. 相似文献
97.
Kanou S Nishimura K Ichikawa M Yoshida J Sakata Y Otsuka M 《Drug development and industrial pharmacy》2008,34(7):771-780
In the presence of urea in solid states, the stability of unpulverized homosulfamine hydrate (phase I; UHH) is significantly decreased whereas that of unpulverized homosulfamine anhydrate (UHA) is not. The stability of UHH is decreased slightly more by pulverization (PHH). The major objective of this study was to investigate the effects of urea, dehydration, and pulverization on the stability of homosulfamine in solid states. Binary mixtures of UHH and urea, PHH and urea, and UHA and urea in a ratio of 1:1 (wt/wt) were prepared as physical mixtures and were analyzed by scanning electron microscopy (SEM), powder X-ray diffraction (PXRD), and Fourier transform infrared (FTIR) spectroscopy to study their appearance and structural changes before and after storage. PXRD analysis revealed that physical mixtures comprising UHH and urea and PHH and urea have the same diffraction pattern as that of the mixture of UHA and urea after preparation. The dehydration rate of the crystal water of UHH was accelerated by the presence of urea in addition to pulverization. Moreover, the PXRD patterns of the physical mixtures of UHH/urea and PHH/urea were significantly altered during storage, whereas that of UHA/urea was not, which was consistent with the SEM and FTIR results. The particle shape and appearance of UHH varied significantly as a result of pulverization. The stability of homosulfamine was influenced not only by the presence of urea and dehydration but also by the surface state and particle size of the crystalline form. 相似文献
98.
Possible involvement of interleukin-1 in cyclooxygenase-2 induction after spinal cord injury in rats
T Tonai Y Taketani N Ueda T Nishisho Y Ohmoto Y Sakata M Muraguchi K Wada S Yamamoto 《Canadian Metallurgical Quarterly》1999,72(1):302-309
A standardized compression injury of rat spinal cord brought about a time-dependent biphasic production of thromboxane A2 (detected as thromboxane B2) and prostaglandin I2 (detected as 6-ketoprostaglandin F1alpha). Thromboxane B2 was predominant during the first 1 h, whereas the 6-ketoprostaglandin F1alpha level exceeded that of thromboxane B2 at 8 h postinjury. As examined by inhibitor experiments and northern blotting, cyclooxygenase-1 was responsible for the first phase, and cyclooxygenase-2 was involved in the second phase. On compression injury the levels of interleukin-1alpha and -1beta detected as mRNA and protein increased and peaked at 2-4 h. Injection of exogenous interleukin-1alpha into the spinal cord resulted in an increase of cyclooxygenase-2 mRNA content and a predominant production of 6-ketoprostaglandin F1alpha resembling the second phase of eicosanoid production. Concomitantly, extravascular migration of polymorphonuclear leukocytes was enhanced after the interleukin-1alpha injection. These cells together with vascular endothelial cells and glial cells were stained positively with an anti-cyclooxygenase-2 antibody. The results suggest that the immediate eicosanoid synthesis after spinal cord injury was due to the constitutive cyclooxygenase-1 and the delayed synthesis of eicosanoids was attributable to the induction of cyclooxygenase-2 mediated by interleukin-1alpha. 相似文献
99.
By using the characteristics of a hydrogen-absorbing alloy, the hydrogen produced by catalytic dehydrogenation of saturated
compounds can be absorbed to form metal hydrides, and, vice versa, the resulting metal hydrides are able to hydrogenate efficiently
unsaturated compounds upon dehydriding. Gas-phase reactions between 2-butene and 2-propanol on a hydrogen-absorbing alloy
CaNi5 have been studied in the temperature range of 393–473 K. CaNi5 showed interesting characteristics as an active catalyst for the catalytic transfer hydrogenation of butene from propanol
as a hydrogen donor. 2-propanol was effectively dehydrogenated at 423 K to yield acetone in which the dissociated hydrogen
was completely absorbed by CaNi5 to form the metal hydride. When the alloy was hydrided to some extent, butene was hydrogenated by the absorbed hydrogen in
the metal hydride to produce butane. The overall reaction on CaNi5 was expressed as catalytic transfer hydrogenation of 2-butene from 2-propanol through intermediate formation of metal hydrides,
rather than the direct reaction between butene and propanol on the alloy. Thus, CaNi5 effectively repeated hydriding–dehydriding cycles: hydriding of CaNi5 by 2-propanol dehydrogenation with subsequent dehydriding for the hydrogenation of 2-butene. The use of hydrogen-absorbing
CaNi5 provides a novel reaction system for the catalytic transfer hydrogenation.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
100.
Matsumoto S. Hirabayashi K. Sakata S. Hayashi T. 《Photonics Technology Letters, IEEE》1999,11(4):442-444
An electrically tunable optical filter has been developed that uses a polymer containing fine droplets of nematic liquid crystal as the active cavity in a Fabry-Perot interferometer (FPI). This FPI filter, whose finesse was 62, had a free spectral range of 37 nm in the 1.55-μm range with a full-width at half maximum of 0.6 nm and a transmission loss of 2.4 dB. The polarization dependent loss was smaller than 0.17 dB. The transmitted peak wavelength decreased with an electric field. This resulted in a tuning range of 10 nm at 300 V. The switching time was about 370 μs 相似文献