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101.
Yoshiyuki Tomita 《Metallurgical and Materials Transactions A》1987,18(8):1495-1501
A modified heat treatment has been suggested whereby lower temperature plane-strain fracture toughness (K
IC) of 4340 ultrahigh strength steel is dramatically improved in developed strength and Charpy impact energy levels. The modified
heat-treated 4340 steel (MHT-4340 steel) consists of a mixed structure of martensite and about 25 vol pct lower bainite which
appears in acicular form and partitions prior austenite grains. This is produced through isothermal transformation at 593
K for a short time followed by an oil quench (after austenitizing at 1133 K and subsequent interrupted quenching in a lead
bath at 823 K). The mechanical properties obtained at room temperature (293 K) and 193 K have been compared with those achieved
using various heat treatments. Significant conclusions are as follows: the MHT-4340 steel compared to the 1133 K directly
oil-quenched 4340 steel increased theK
IC values by 15 to 20 MPa • m1/2 at increased strength and Charpy impact energy levels regardless of the test temperature examined. At 193 K,K
IC values of the MHT-4340 steel were not less than those of the 1473 K directly oil-quenched 4340 steel, in whichK
IC values are significantly enhanced at markedly increased strength, ductility, and Charpy impact energy levels. The MHT-4340
steels compared to austempered 4340 steels at 593 K, which have excellent Charpy impact properties, showed superiorK
IC values at significant increased strength levels irrespective of test temperatures. The lower temperature improvement inK
IC can be attributed to not only the crack-arrest effect by acicular lower bainite but also to the stress-relief effect by the
lower bainite just ahead of the current crack. 相似文献
102.
Shigeo Yamabe Kazuo Kobayashi-Hattori Kentaro Kaneko Hiroshi Endo Toshichika Takita 《Food chemistry》2007,100(1):369-374
To clarify the effect of soybean varieties on isoflavone, a useful component for human health, in soybean products, we investigated changes in the isoflavone content and composition in rice-koji miso, after fermentation/aging for 6 or 12 months using varieties of soybeans (Tohoku-126, Tohoku-135, Tohoku-139, Suzuyutaka and Chinese soybeans), by high performance liquid chromatography. In soybeans, the total isoflavone content in Tohoku-126 was 444 mg/100 g, which was 1.2–2.0 times the content in the other soybean varieties. The malonyl glycosides and aglycones in soybeans accounted for more than 60% and only a few percent, respectively. As for rice-koji miso, the total isoflavone and aglycone contents were the highest in miso prepared from Tohoku-126. The ratios of glycosides to aglycones (80.1–92.6%) in miso were higher than those in the original soybeans. The time course of the isoflavone composition during the fermentation/aging process of rice-koji miso indicated that glycosides decreased from 86.4% to 44.9% after 6 months but aglycones increased from 9.6% to 53.3%. 相似文献
103.
Hyun-Chul Ko Doo-Cheol Park Yoichi Kawakami Shizuo Fujita Shigeo Fujita Chai-ok Kim 《Journal of Materials Science Letters》1997,16(13):1187-1190
Abstracts are not published in this journal
This revised version was published online in November 2006 with corrections to the Cover Date. 相似文献
104.
The molecular chain network model for elastic deformation behavior and the reptation theory for viscoelastic deformation behavior are used to derive a constitutive equation for rubber. The new eight-chain-like model contains eight standard models consisting of Langevin springs and dashpot to account for the interaction of chains with their surroundings. Monotonic and cyclic deformation behavior of rubber with relaxation under different strain rates have been examined. The results reveal the roles of the individual springs and dashpot, and the strain rate dependence of materials in the monotonic and cyclic deformation behaviors, particularly softening and hysteresis loss, that is, the Mullins effect, occurring in stress-stretch curves under cyclic deformation processes. The validity of the results is checked through comparison with experimental results. The deformation behaviors of a plane strain rubber unit cell containing carbon-black (CB) under monotonic and cyclic straining are investigated by computational simulation using the proposed constitutive equation and homogenization method. The results reveal the substantial enhancement of the resistance of CB-filled rubber to macroscopic deformation, which is caused by the marked orientation hardening due to the highly localized deformation of rubber. The role of strain rate sensitivity on such characteristic deformation behaviors as increases in the resistance to deformation, hysteresis loss, and the effects of the distribution morphology and the volume fraction of CB on the deformation behavior is clarified. The increases in the volume fraction and in the aggregation of the distribution of CB substantially raise the resistance to deformation and hysteresis loss. 相似文献
105.
106.
L. Hawelek A. Brodka J.C. Dore V. Honkimaki S. Tomita A. Burian 《Diamond and Related Materials》2008,17(7-10):1186-1193
The atomic scale structure of explosive diamond nanoparticles has been studied using high-energy X-ray diffraction. The diffraction data have been converted to the real space representation in the form of the radial distribution function. Spherical and truncated octahedron nanodiamond clusters containing from 729 to 1182 atoms have been computer generated and then relaxed using the molecular dynamics method with the reactive empirical bond order potential for carbon-carbon interaction and the Lennard–Jones potential with parameters for inter-layer interactions. Validity of such constructed models has been verified by comparison of the simulations and the experimental data in both real and reciprocal space. The obtained results show that the structure of the investigated diamond nanoparticles cannot be satisfactorily described in terms of the model based on the perfect diamond lattice. The core-shell model with an average size of 22.5–23.4 Å, consisting of the diamond core and the graphite-like shell, accounts very well for the experimental data. 相似文献
107.
A relationship between emission characteristics of Ba atom as an emitter material and temperature distributions of an electrode in a fluorescent lamp is described, which is measured by using laser-induced fluorescence and black-body radiation method, respectively. In a virgin lamp, a hot spot observed at the electrode edge connected to the power supply is the main source of Ba atom emission. In a long-term-used lamp, it is shown that Ba atom emission, thermionic electron emission in cathode half-cycle and electron collection in anode half-cycle are most active on the hot spot appearing on the center of the electrode. 相似文献
108.
Ekman Paul; Friesen Wallace V.; O'Sullivan Maureen; Chan Anthony; Diacoyanni-Tarlatzis Irene; Heider Karl; Krause Rainer; LeCompte William Ayhan; Pitcairn Tom; Ricci-Bitti Pio E.; Scherer Klaus; Tomita Masatoshi; Tzavaras Athanase 《Canadian Metallurgical Quarterly》1987,53(4):712
We present here new evidence of cross-cultural agreement in the judgment of facial expression. Subjects in 10 cultures performed a more complex judgment task than has been used in previous cross-cultural studies. Instead of limiting the subjects to selecting only one emotion term for each expression, this task allowed them to indicate that multiple emotions were evident and the intensity of each emotion. Agreement was very high across cultures about which emotion was the most intense. The 10 cultures also agreed about the second most intense emotion signaled by an expression and about the relative intensity among expressions of the same emotion. However, cultural differences were found in judgments of the absolute level of emotional intensity. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
109.
Yoshiyuki Tomita 《Journal of Materials Science》1989,24(4):1357-1362
The modified heat treatment, which produces a mixed structure of martensite and lower bainite through short-term isothermal
transformation at just above the martensitic transformation temperature,M
s
temperature, followed by oil quenching (after conventional austenitization), has been applied to three high-carbon low-alloy
steels with different levels of nickel and chromium contents at similar molybdenum levels, in which carbon was allowed to
replace relatively expensive additions of nickel and chromium, for their ultra-high strength application. The significant
conclusions are as follows: an ultra-high strength steel of 1900 M Pa yieldstress grade with a high toughness level can be
obtained when about 60 vol % lower bainite is associated with 473 K tempered martensite of 0.60% C-1.80% Ni-0.80% Cr-0.25%
Mo steel. If approximately 25 vol % lower bainite appears in 673 K tempered martensite of the steel, a 1700 M Pa yield-stress
grade steel with high toughness and moderate ductility levels can be attained. However, alloying nickel is essential to some
extent for development of the mechanical properties with the modified heat treatment suggested in the present work. 相似文献
110.
The purpose of the present study is to examine whether isolated Schwann cells that are not in contact with axons can synthesize the basement membrane in vivo. Schwann cells obtained from sciatic nerve of neonate Wistar rats were prepared in culture, harvested, and mixed with collagen matrix. The silicone tube filled with the collagen matrix containing Schwann cells was closed by a Millipore membrane at both ends to isolate the interior from the outer environment and was implanted in a gap between proximal and distal stumps of transected sciatic nerve of an adult Wistar rat. Ten days later, the implanted silicone tube was prepared for electron microscopic observations. Schwann cells in the tube were elongated longitudinally and lined up parallel to the proximo-distal direction. No regenerating axons penetrated the Millipore membrane into the tube. The basement membrane showing almost normal structure was produced on the surface of the Schwann cells. While the silicone tube was placed side by side to the intact sciatic nerve, Schwann cells in the tube were scattered and no basement membrane was observed. These results suggest that some humoral factors might be released from the transected nerve stumps, which may be responsible for the regular arrangement and the basement membrane formation by Schwann cells without any contact with axons. 相似文献