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81.
Thecautious scheduler, recently proposed for the concurrency control of database systems, never resorts to abortions or rollbacks for the purpose of concurrency control. The comprehensive performance evaluation study among different cautious schedulers and conventional non-cautious schedulers, however, has not yet been attempted. In this paper, we consider five scheduling algorithms and investigate their performance by means of simulation studies. Two of these algorithms are non-cautious; that is, thetwo-phase locking algorithm (2PL) (the most popular transaction scheduling algorithm in practical systems) and theconflict serializable algorithm (CSR) (a typical scheduling algorithm among those not using a locking mechanism; also calledD-serializable algorithm, conflict preserving serializable algorithm, orWW-serializable algorithm). The others are cautious scheduling algorithms modified from the above2PL andCSR; that is,cautious two-phase locking algorithm (C2PL), exclusive preclaimed two-phase locking algorithm (EP2PL), andcautious conflict serializable algoritm (CCSR). The results demonstrate the superiority of the cautious conflict serializable algorithm over the conventional two-phase locking algorithm, especially in the on-line system environment.This work was supported in part by the Ministry of Education, Science and Culture of Japan under Scientific Research Grant-in-Aid and in part by the Advancd Systems Foundations of British Columbia, Canada. 相似文献
82.
Polyethylene reactor powders prepared under different conditions were characterized using transmission electron microscopy, 1H nuclear magnetic resonance and X-ray diffraction techniques. The molecular weight of the polyethylene reactor powders was around 1 × 105. A unique domain morphology, quite different from the usual melt- or solution-crystallized lamellar structure, was observed, independent of polymerization temperature (Tpoly). Annealing of reactor powders caused the aggregation of these crystalline domains, due to the significant molecular motion of the amorphous chains, before melting. The critical temperature was 20 °C higher than each Tpoly, and corresponded to the temperature at the active catalyst site producing the chain growth. The morphologies of powders prepared at the lower Tpoly contained smaller crystals that exhibited a constrained monoclinic form. In contrast, only usual orthorhombic crystals of larger size were found within the powder prepared at the higher Tpoly. These results suggest that the competitive processes of chain propagation and crystal growth upon polymerization may lead to unique variations of the crystalline and amorphous phases, but with similar intermediate components in the phase that connects them. 相似文献
83.
Yoshino M. Kaneko S. Taniguchi T. Miki N. Kumozaki K. Imai T. Yoshimoto N. Tsubokawa M. 《Lightwave Technology, Journal of》2008,26(8):962-970
In order to relax the limitation of the number of multiplexed signal lights caused by beat noise between signal lights, we investigate the applicability of a heterodyne detection technique to a spectral amplitude coding optical code division multiple access scheme. In this investigation, for the first time, we found analytically that the optical frequency chips that form parts of the signal and local lights require uniform phase differences even for envelope detection. We also confirm this requirement and our theoretical analysis experimentally. 相似文献
84.
Miyake J. Maeda T. Nishimichi Y. Katsura J. Taniguchi T. Yamaguchi S. Edamatsu H. Watari S. Takagi Y. Tsuji K. Kuninobu S. Cox S. Duschatko D. MacGregor D. 《Solid-State Circuits, IEEE Journal of》1990,25(5):1199-1206
A 1-million transistor 64-b microprocessor has been fabricated using 0.8-μm double-metal CMOS technology. A 40-MIPS (million instructions per second) and 20-MFLOPS (million floating-point operations per second) peak performance at 40 MHz is realized by a self-clocked register file and two translation lookaside buffers (TLBs) with word-line transition detection circuits. The processor contains an integer unit based on the SPARC (scalable processor architecture) RISC (reduced instruction set computer) architecture, a floating-point unit (FPU) which executes IEEE-754 single- and double-precision floating-point operations a 6-KB three-way set-associative physical instruction cache, a 2-KB two-way set-associative physical data cache, a memory management unit that has two TLBs, and a bus control unit with an ECC (error-correcting code) circuit 相似文献
85.
Yuki Matsushita Junko Taniguchi Ryo Toda Hiroki Ikegami Taku Matsushita Mitsunori Hieda Nobuo Wada 《Journal of Low Temperature Physics》2008,150(3-4):342-346
We have studied heat capacities of 4He adsorbed in straight nanopores 1.8, 2.2, and 2.8 nm in diameter. Heat capacities of the 4He fluid film on the solid layer at 0.08–0.4 K show power laws close to T in 1.8 nm pores, close to T
2 in 2.8 nm pores, and a crossover from T to T
2 with increasing temperature in 2.2 nm pores. These heat capacities are explained by a model assuming a phonon dispersion
with continuous one-dimensional (1D) states in the axial direction and discrete energy levels in the azimuthal direction.
By fitting experimental data to the model, the phonon velocity along the pore axis and the energy gap for propagation in the
cross section are derived. At temperatures sufficiently lower than the energy gap, where the thermal wave length of phonons
is much longer than the effective pore diameter, the 4He fluid films show a T-linear heat capacity of 1D phonons propagating only along the pore axis. At higher temperatures, a 1D-2D crossover of phonons
occurs.
相似文献
86.
Chigusa S. Maeda H. Taniguchi Y. Hayakawa N. Okubo H. 《Dielectrics and Electrical Insulation, IEEE Transactions on》1999,6(3):385-392
We have been studying quench-induced `dynamic' breakdown characteristics of LHe and have already found that the electrical insulation performance of LHe was degraded drastically by the thermal bubble disturbance due to quench of superconductors. In this paper, in order to improve the insulation performance of LHe under quench conditions, we measured dynamic breakdown and prebreakdown characteristics of pressurized LHe. Experimental results revealed that breakdown voltage of LHe under quench conditions at 0.2 MPa was greatly improved, reaching 2 to 4× compared with that at atmospheric pressure under both uniform and non-uniform electric fields. Moreover, for practical and efficient insulation design of superconducting power apparatus, we investigated the dynamic breakdown voltage of LHe as functions of pressure and gap length 相似文献
87.
The oxidation kinetics of cold-rolled Remko iron coupons in purified oxygen at atmospheric pressure in the temperature range 973–1173K and the morphologies of both oxide scales and subtrate surfaces were studied using thermogravimetric, metallographic and scanning electron-microscope techniques.Parabolic oxidation rate constants were found to decrease after initial varying periods of constancy, an effect believed to be due to void formation at the wüstite/iron interfaces by the coalescence of vacancies. The observed subsequent recoveries of the values of the rate constants were considered to be due to an increase in oxide growth stresses to values large enough to cause appreciable plastic flow of oxide, thereby decreasing the number of interfacial voids.The extent of the deviations from the initial values of the rate constants decreased as the oxidation temperature was increased and this was considered to be due to the enhanced plasticity of the scale and increased rate of stress generation which favoured the elimination of the interfacial voids.In the temperature range 973–1073K, there were periods in which logarithmic growth relationships were observed, the mechanism being similar to that suggested by Evans, and involving a continuous increase in the number of interfacial voids. 相似文献
88.
Hisaho Hashimoto Ayako Demachi Toyoki Nishimata Yasuaki Sasamura Kazutoshi Iida Noriaki Kaneko Nagayoshi Sakamoto Toyoji Kakuchi Kazuaki Yokota 《大分子材料与工程》1989,172(1):177-183
A new method of introducing a hydrophilic polyether side chain into segmented polyurethane using a polypropylene oxide macromer with 1,3-diol at one chain-end, which behaves as chain extender, is described. In this procedure, a molecular-designed side-chain is incorporated quantitatively and directly into polyurethane biomedical elastomer. The design is also of interest to biomaterials in artificial organs. 相似文献
89.
T. Taniguchi 《Computers & Structures》1991,41(6):1295-1303
A system for crack propagation analysis based on the finite element method is shown. The system is easily applied to the investigation of crack propagation behavior due to fatigue in arbitrary structural members of, for example, steel bridges. Moreover, the user can estimate the residual life of the structure with respect to the fatigue-crack. This paper also includes new mesh generation methods for this purpose, and several numerical examples show the efficiency of the mesh generation and the analysis system. 相似文献
90.
Uniform carrier injection into the channel of n-MOSFETs generates two types of interface states, depending on the oxide electric field: One is linearly proportional to the injected electron density (Type I), while the other shows a half-power dependence (Type II). Charge-pumping measurements in the temperature range of 77K and 263K show that the type I interface states are located in the mid-gap, while the type II interface states are uniformly distributed in wide energy range. Holes generated at the gate/SiO2 interface or in the oxide are found to be responsible for the type I interface states, while hydrogen or hydrogen compounds diffusing from the interface cause the type II interface states. 相似文献