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71.
Fujita K Osuka H Fujiki T Yoneyama S Sengoku K Sumiya Y Watanabe M Mizutani Y Zhao X Hirose T 《Shokuhin eiseigaku zasshi. Journal of the Food Hygienic Society of Japan》2005,46(6):294-297
Inter-laboratory validation studies were conducted in 6 laboratories to validate the analytical method for determination of chloramphenicol in royal jelly. Chloramphenicol spiked at the levels of 0.1 and 0.5 ppm was analyzed. Mean recoveries were 89 and 89%, reproducibility relative standard deviations (RSD(R)) were 10.5 and 6.8%, HORRAT(R) values were 0.5 and 0.4. Samples containing residues at the levels of 0.25 and 0.80 ppm were analyzed. Mean recoveries were 89 and 84%, RSD(R) were 9.8 and 12.3%, and HORRAT(R) values were 0.5 and 0.7. The determination limit was 0.05 ppm. These results show that this method has good performance. 相似文献
72.
A.?KojimaEmail author H.?Sasou K.?Tozaki T.?Okazaki Y.?Yoshimura N.?Tokunaga H.?Iwasaki 《International Journal of Thermophysics》2005,26(6):1963-1972
In order to obtain useful information on the transient process of phase transitions in ferroelectrics by various methods including
calorimetry, the “mK-stabilized cell” of a small size has been developed. It is based on the heat flux differential scanning
calorimeter (DSC) and has a temperature stability better than 1 mK. The “cell” can be used to change the temperature under
nearly quasi-static conditions by an infinitesimally small rate not only on heating but also on cooling while passing through
the transition points. It enables simultaneous measurements of endothermic heat and exothermic heat along with dielectric
constants, displacement currents, etc. with a high degree of temperature resolution. X-ray diffraction measurements for sensing
thermal anomalies are also possible by a minor modification of the “cell.” Precise and simultaneous measurements of thermal,
electrical, and acoustic properties were carried out at the 403 K phase transition in BaTiO3 single crystal grown by the top-seeded solution growth method. It has been clarified that the exothermic heat at the transition
on cooling has more useful information than the endothermic heat on heating; in the cooling process two thermal anomalies
occur separately at T1 and T2 although the transition is in a narrow temperature range. It is recognized from other methods that the nature of the transition
on cooling is not of a single but of multiple steps. Resonant ultrasonic measurements using the “cell” were carried out, after
developing a new excitation method. The sample does not have a simple softening approaching the transition point on cooling
but has different elastic moduli for the two thermal anomalies at T1 and T2. The dielectric constant also has an intermediate constant value between T1 and T2. The crystal structure in the room temperature phase below the transition point has been determined by X-ray diffraction.
In this region, tetragonal and monoclinic structures coordinating with each other exist.
Paper presented at the Fifteenth Symposium on Thermophysical Properties, June 22–27, 2003, Boulder, Colorado, U.S.A. 相似文献
73.
Shin Yagihara Nobuhiro Miura Yoshihito Hayashi Hidenori Miyairi Megumi Asano Gaku Yamada Naoki Shinyashiki Satoru Mashimo Toshihiro Umehara Maysayuki Tokita Satoru Naito Tohru Nagahama Masami Shiotsubo 《Subsurface Sensing Technologies and Applications》2001,2(1):15-30
Microwave dielectric measurements were performed in the frequency range from 1 mHz up to 30 GHz using a time domain reflectometry (TDR) method for emulsions and gels. Flat-end sample cells have been used in the TDR measurement to contact a small spot of the surface of those viscoelastic and solid samples without any destruction. Relaxation processes due to various water structures were observed for these aqueous systems. Relaxation parameters thus obtained offer information about these water structures and amounts. The relaxation strength obtained from the high frequency process due to free water can be an adequate measure of water content in spite of some ambiguities for different water structures in some materials. Comparisons of actual water contents in emulsion with those estimated from the relaxation strength indicate that water structure is affected by the interaction between water and micelle. Unfreezable water observed in DNA gel under the freezing point consists of bound water and a fraction of free water. Bound water molecules are still unfreezable to keep the double helical structure of DNA, when the fraction of free water is frozen at lower temperatures. These water structures determine physical properties of moist materials. TDR measuring technique with the flat-end cell is effective to investigate water structures in viscoelastic moist materials and to evaluate physical properties and structures of complex molecular systems. 相似文献
74.
Hirofumi Sanada Hiroaki Ito Megumi Takezawa Kazuhisa Watanabe 《IEEJ Transactions on Electrical and Electronic Engineering》2007,2(6):588-595
A method for designing microwave filters and impedance matching circuits using transmission lines is presented. Transmission line filters with shunt‐connected open circuit stubs and continuously varying transmission line matching circuits are described in detail. The proposed method is based on genetic algorithms and can effectively be applied to various filter and matching circuit design problems without increasing theoretical and computational complexity. Design examples are provided, and the proposed method is demonstrated to be effective in designing transmission line filters and matching circuits. Copyright © 2007 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. 相似文献
75.
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78.
Yoshida I Isagawa S Kibune N Hamano-Nagaoka M Maitani T 《Shokuhin eiseigaku zasshi. Journal of the Food Hygienic Society of Japan》2007,48(4):83-89
Furan is a 5-membered ring compound with high volatility. The U.S. Food and Drug Administration (FDA) has recently published a report on the occurrence of furan in a large number of thermally processed foods. However, the FDA's analytical method, using standard curve addition, is not suitable for high-throughput routine laboratory operations. We developed a rapid and improved method for determination of furan in foods by headspace GC/MS. Quantification was achieved by using an internal standard of d4-furan and an external calibration curve of furan normalized against the internal standard. The incubation temperature for equilibration was set at 60 degrees C to avoid the formation of furan during analysis. The levels of furan in baby foods and infant formulas were determined with this method. Validation data showed good precision and accuracy. The LOD and LOQ were 0.2-0.5 ng/g and 0.5-2 ng/g for various food matrixes, respectively. The level of furan detected was in the range of 1.4 to 90 ng/g in baby foods and in the range of non-detectable to 36 ng/g in infant formulas. 相似文献
79.
Akai-Kasaya M Shimada N Saito A Kuwahara Y 《Journal of nanoscience and nanotechnology》2011,11(4):2867-2872
The injection of charge carriers into a pentacene thin film formed on a Si substrate was investigated by scanning tunneling microscopy (STM). Tip height versus bias voltage (z-V) spectroscopy reveals the characteristic charge transport properties of the molecular film, i.e., the conductivity and the threshold energy of charge injection. The abrupt descent of the tip into the film owing to the transition of film conductance, which depends on the degree of charge carrier injection, was observed for crystallized pentacene thin films. The lower film conductance at around zero bias voltage is still higher than that of a vacuum. This indicates that the carrier injection barrier between the pentacene and the semiconducting substrate is extremely low. The convergence of the carrier injection endpoints into a narrow range of electric-field intensity implies that the main factor contributing to barrier formation and collapse is not the bias voltage but the electric field. 相似文献
80.
Megumi Kawasaki Roberto B. Figueiredo Cheng Xu Terence G. Langdon 《Metallurgical and Materials Transactions A》2007,38(9):1891-1898
Conventional superplasticity is generally achieved in metals having grain sizes in the range of ∼2 to 5 μm, but processing
by equal-channel angular pressing (ECAP) provides the opportunity of introducing exceptional grain refinement and producing
materials with ultrafine grain sizes in the submicrometer range. These materials have the potential for exhibiting excellent
superplastic properties when tested in tension at elevated temperatures and examples are presented for representative aluminum
and magnesium alloys. When these ultrafine-grained materials deform in superplasticity, internal cavities develop as in conventional
superplastic alloys. An example is presented for an aluminum-based alloy, and it is shown that the cavity growth processes
are also similar to those in conventional alloys.
This article is based on a presentation made in the symposium entitled “Ultrafine-Grained Materials: From Basics to Application”,
which occurred September 25–27, 2006, in Kloster Irsee, Germany. 相似文献