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排序方式: 共有950条查询结果,搜索用时 15 毫秒
941.
942.
943.
Yasuo Cho Koya Ohara Satoshi Kazuta Hiroyuki Odagawa 《Integrated ferroelectrics》2013,141(1-4):133-142
Abstract A theory for scanning nonlinear dielectric microscopy (SNDM) and its application tothe quantitative evaluation of the linear and nonlinear dielectric constants of dielectric materials are described. First, a general theorem for the capacitance variation under an applied electric field is derived and a capacitance variation susceptibility Snl , which is a very useful parameter for the quantitative measurement of nonlinear dielectric constants, is defined. This Snl is independent of the tip radius, and therefore the sensitivity of the SNDM probe does not change, even if a tip with a smaller radius is selected to obtain a finer resolution. Using the theoretical results and the data taken by SNDM, the quantitative linear and nonlinear dielectric properties of several dielectric materials were successfully determined. From the calculation of a one-dimensional image of a 180 ° c-c domain boundary, it is demonstrated that the SNDM has an atomic scale resolution. 相似文献
944.
A previous paper described a method of extracting long sequences of border points from images of mechanical parts, by linking points having high edge values that lie on the borders of thresholded regions. This paper develops methods of fitting polygons and arcs of ellipses to the border sequences. The results are applied to finding small holes in images of connecting rods. 相似文献
945.
Yasuo Wakabayashi Atsushi Taketani Takao Hashiguchi Yoshimasa Ikeda Tomohiro Kobayashi Sheng Wang 《Journal of Nuclear Science and Technology》2018,55(8):859-867
A function to give the total neutron production cross section, angular distribution, and energy spectrum via the 9Be + p reaction has been created by fitting experimental data to characterize compact neutron sources with thick Be targets bombarded by protons with energy below 12 MeV. To examine the suitability of the function, calculations of the angle-dependent neutron energy spectra produced in thick Be targets with 4- and 12-MeV protons using the function were compared with corresponding experiments and calculations using the nuclear data libraries of ENDF/B-VII.0 and JENDL4.0/HE. The function was in better agreement with the experiments than the calculations using the libraries except for at backward angles. The 115In(n,n’)115mIn reaction rates calculated using GEANT4 with source neutrons given by both the function and ENDF/B-VII.0 were compared with that measured at the RIKEN Accelerator-Driven Compact Neutron Source to evaluate the neutron spectrum above 1 MeV. The function slightly overestimated the measurement by 14% and the calculation with ENDF/B-VII.0 underestimated by 35%. It was concluded that the function can be applied in compact neutron source designs. 相似文献
946.
Satoshi Seino Yasuo Imoto Daijiro Kitagawa Yoshiki Kubo Tomoya Kosaka Takao Kojima 《Journal of Nuclear Science and Technology》2016,53(7):1021-1027
This paper presents a new technique for synthesizing silver nanoparticles immobilized on textile fabrics using a radiochemical process. In this process, the irradiation of a high-energy electron beam on an aqueous solution containing silver ions induces a reducing reaction that forms metallic silver nanoparticles. Small Ag particles of about 2–4 nm were observed together with relatively large particles of more than 10 nm. These nanoparticles are firmly immobilized on the surface of a support textile fabric without the need for any binder or surfactant. The amount of silver nanoparticles immobilized was found to depend on the water content of the support textile fabric, suggesting that the silver ions are reduced not only by radiochemical species generated by the radiolysis of water, but also by radiochemical species generated in the irradiated support fabric itself. The silver nanoparticles that were immobilized on the support textile fabric exhibited an excellent antibacterial activity across a wide antibacterial spectrum, even after a durability test involving washing the fabric 100 times. 相似文献
947.
Seiji Kawai Yohei Katsuyama Yasuo Ohnishi 《Chembiochem : a European journal of chemical biology》2022,23(7):e202100700
During the biosynthesis of alazopeptin, a tripeptide composed of two molecules of 6-diazo-5-oxo-L-norleucine (DON) and one of alanine, the α/β hydrolase AzpM synthesizes the DON-DON dipeptide using DON tethered to the carrier protein AzpF (DON-AzpF). However, whether AzpM catalyzes the condensation of DON-AzpF with DON or DON-AzpF remains unclear. Here, to distinguish between these two condensation possibilities, the reaction catalyzed by AzpM was examined in vitro using a DON analogue, azaserine (AZS). We found that AzpM catalyzed the condensation between AZS-AzpF and DON-AzpF, but not between AZS-AzpF and DON. Possible reaction intermediates, DON-DON-AzpF and AZS-AZS-AzpF, were also detected during AzpM-catalyzed dipeptide formation from DON-AzpF and AZS-AzpF, respectively. From these results, we concluded that AzpM catalyzed the condensation of the two molecules of DON-AzpF and subsequent hydrolysis to produce DON-DON. Thus, AzpM is an unprecedented α/β hydrolase that catalyzes dipeptide synthesis from two molecules of a carrier protein-tethered amino acid. 相似文献
948.
In this paper, we propose a new antidrone surveillance system with multiple vehicles and bistatic radars whose antennas are mounted in each vehicle. The proposed system is based on the broadcast control technique recently proposed. We show that our method provides the optimal formation in terms of the received signal level of echoes from the drone intruders, without the information about the relation among the signal level, the locations of vehicles, and the locations of intruders. The proposed system is demonstrated by numerical simulation. 相似文献
949.
Dr. Hayama Tsutsumi Prof. Yohei Katsuyama Dr. Takeaki Tezuka Dr. Rei Miyano Dr. Yuki Inahashi Dr. Yoko Takahashi Dr. Takuji Nakashima Prof. Yasuo Ohnishi 《Chembiochem : a European journal of chemical biology》2022,23(3):e202100517
Indolizidine alkaloids, which have versatile bioactivities, are produced by various organisms. Although the biosynthesis of some indolizidine alkaloids has been studied, the enzymatic machinery for their biosynthesis in Streptomyces remains elusive. Here, we report the identification and analysis of the biosynthetic gene cluster for iminimycin, an indolizidine alkaloid with a 6-5-3 tricyclic system containing an iminium cation from Streptomyces griseus. The gene cluster has 22 genes, including four genes encoding polyketide synthases (PKSs), which consist of eight modules in total. In vitro analysis of the first module revealed that its acyltransferase domain selects malonyl-CoA, although predicted to select methylmalonyl-CoA. Inactivation of seven tailoring enzyme-encoding genes and structural elucidation of four compounds accumulated in mutants provided important insights into iminimycin biosynthesis, although some of these compounds appeared to be shunt products. This study expands our knowledge of the biosynthetic machinery of indolizidine alkaloids and the enzymatic chemistry of PKS. 相似文献
950.
Yoshitaka Ono Sho Nagai Yasuo Hayashi Shu-hei Urashima Hiroharu Yui 《Journal of the American Ceramic Society》2023,106(7):4052-4060
It is essential to etch SiO2 for producing silica glass components, semiconductor devices, and so on. Although wet-etching with hydrogen fluoride (HF) solutions is usually employed for this purpose, it faces a drawback that microstructures stick during the drying of the solution. To overcome this problem, we have developed a dry-etching technique with gaseous HF at high temperatures. In the present study, an interesting phenomenon was found that silicon thermal oxides were much less etched than vitreous silica by gaseous HF. Such difference had not been found in wet- or humid HF gas etching. Because their bulk chemical formulae are the same (SiO2), it was suggested that the surface species affected the reaction rate. In fact, preprocessing with water vapor plasma remarkably increased the etching rate on the thermal oxides layer, and vacuum heating almost completely suppressed the reaction on the vitreous silica and the plasma-treated thermal oxides. These results indicate that the surface silanol groups enhance the reaction between SiO2 and gaseous HF. Based on the results, a model of chain reaction for SiO2 and gaseous HF was proposed, where the surface silanol groups act as the reaction center. 相似文献