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101.
Oleg D. Sherby Rodney H. Klundt Alan K. Miller 《Metallurgical and Materials Transactions A》1977,8(6):843-850
Well defined subgrain boundaries dominate the microstructural changes occurring during plastic flow of polycrystalline metals
at elevated temperature. The quantitative influence of subgrain size on elevated-temperature plastic flow is considered. Based
on the results of tests under constant-stress and constant-structure conditions, an equation is developed which predicts the
creep rate as a function of subgrain size, stress, diffusion coefficient, and elastic modulus. In general, the subgrain size
is a unique function of the current modulus-compensated flow stress, but if fine subgrains can be introduced and stabilized,
large increases in creep strength may result. The applicability of the phenomenological relation developed to the behavior
of dispersion-strengthened materials (where the second-phase particles may predetermine the effective subgrain size) is discussed.
When subgrain effects are included, it is shown that the creep rate is less dependent on stacking fault energy than has been
previously thought.
This paper is based on a presentation made at a symposium on “Mechanical-Thermal Processing and Dislocation Substructure Strengthening,”
held at the Annual Meeting in Las Vegas, Nevada, on February 23, 1976, under the sponsorship of the TMS/IMD Heat Treating
Committee. 相似文献
102.
Oleg?SukhoruchkoEmail author Anatoly?Tishchenko 《Journal of Infrared, Millimeter and Terahertz Waves》2005,26(1):65-70
The paper considers the experimental and analytical data on volt-watt characteristics of metal-semimetal BiSb film point contacts in 8 millimeter wavelength range. Analytical expressions have been obtained for the volt-watt sensitivity and the resistance of the metal-semimetal BiSb film point contacts. A thermoelectric millimeter wave range detector has been designed on the basis of the sensors; the performance is illustrated by experimentally determined volt-watt relations. 相似文献
103.
Tischenko O Hoeschen C Dance DR Hunt RA Maidment AD Bakic PR 《Radiation protection dosimetry》2005,114(1-3):81-84
A novel method of noise reduction has been tested for mammography using computer-simulated images for which the truth is known exactly. This method is based on comparing two images. The images are compared at different scales, using a cross-correlation function as a measure of similarity to define the image modifications in the wavelet domain. The computer-simulated images were calculated for noise-free primary radiation using a quasi-realistic voxel phantom. Two images corresponding to slightly different geometry were produced. Gaussian noise was added with certain properties to simulate quantum noise. The added noise could be reduced by >70% using the proposed method without any noticeable corruption of the structures. It is possible to save 50% dose in mammography by producing two images (each 25% of the dose for a standard mammogram). Additionally, a reduction of the anatomical noise and, therefore, better detection rates of breast cancer in mammography are possible. 相似文献
104.
Herein we demonstrate a unique processing technique for engineering multicomponent ceramic nanopowders with precise morphologies by "nanoblast" calcination/deagglomeration. Multiple "nanoexplosions" of C(3)H(6)N(6)O(6) nanoparticles embedded in preliminary engineered nanoreactors break apart the agglomerates because of the highly energetic impacts of the blast waves. Also, the solid-solubility of one component into the other is enhanced by the extremely high local temperature generated during the nanoexplosions. We applied this technique to produce nanosized agglomerate-free ceria-gadolinia solid solution powder with an average aggregate size of 42 nm. The described method opens the door to the synthesis of a wide range of multimetal oxide ceramic and metal-ceramic composite nanopowders, with precise stoichiometries and uniform morphologies. 相似文献
105.
Tatiana V. Magdesieva Magdalena Graczyk Oleg M. Nikitin Kim P. Butin 《Electrochimica acta》2006,52(3):1265-1280
We have studied a reaction between the reduced form of titanocene dichloride (Cp2TiCl2) and a group of organic halides: benzyl derivatives (4-XC6H4CH2Cl, X = H, NO2, CH3; 4-XC6H4CH2Br, X = H, NO2, PhC(O); 4-XC6H4CH2SCN, X = H, NO2) as well as three aryl halides (4-NO2C6H4Hal, Hal = Cl, Br; 4-CH3O-C6H4Cl). It has been shown that the electrochemical reduction of Cp2TiCl2 in the presence of these benzyl halides leads to a catalytic cycle resulting in the reductive dehalogenation of these organic substrates to yield mostly corresponding toluene derivatives as the main product. No dehalogenation has been observed for aryl derivatives. Based on electrochemical data and digital simulation, possible schemes of the catalytic process have been outlined. For non-substituted benzyl halides halogen atom abstraction is a key step. For the reaction of nitrobenzyl halides the complexation of Ti(III) species with the nitro group takes place, with the electron transfer from Ti(III) to this group (owing to its highest coefficient in LUMO of the nitro benzyl halide) followed by an intramolecular dissociative electron redistribution in the course of the heterolytic CHal bond cleavage.The results for reduced titanocene dichloride centers immobilized inside a polymer film showed that the catalytic reductive dehalogenation of the p-nitrobenzyl chloride does occur but with a low efficiency because of the partial deactivation of the film due to the blocking of the electron charge transport between the electrode and catalytic centers. 相似文献
106.
Vitalina M. Nikitina Oksana V. Nesterova Vladimir N. Kokozay Viktoriya V. Dyakonenko Oleg V. Shishkin Julia Jezierska 《Inorganic chemistry communications》2009,12(2):101-104
The one-pot self-assembly reaction of copper powder, Reineckes salt, acetone and tris(2-aminoethyl)amine (tren) in dmso affords to obtain a heterometallic compound [Cu(trenac)][Cr(NCS)4(NH3)2](NCS) · 6dmso with novel Schiff-base ligand N-(2-{[(1E)-3-amino-1,3-dimethylbutylidene]amino}ethyl)-N-(2-aminoethyl)ethane-1,2-diamine (trenac). The ligand trenac is generated by metal-directed condensation of tren, acetone and ammonia, formed during the synthetic procedure. X-ray structural investigations showed that the complex consists of [Cu(trenac)]2+ cations, anions of the Reineckes salt [Cr(NCS)4(NH3)2]?, uncoordinated thiocyanate groups and dmso molecules, which are held together by electrostatic forces and hydrogen-bonded interactions. The compound was characterized by EPR spectroscopic and magnetic susceptibility measurements. 相似文献
107.
Ruturaj Deshpande Sergiy Antonyuk Oleg Iliev 《American Institute of Chemical Engineers》2019,65(4):1294-1303
This study aims to investigate the sedimentation and the consolidation of the packed bed/cake formed due to the monodispersed and bidispersed particles under different flow conditions. Mutual interactions between the bidispersed particles and the liquid are considered by using a polydispersed drag model. The attractive force is considered by using the JKR model. Sensitivity of the void fraction of a sedimented packed bed/cake due to particle–particle interaction parameters is studied. Furthermore, the effect of the fluid flow is analyzed by performing the simulations in two stages. In the first stage, packed bed/cake is formed by the sedimentation of the particles in the absence of the fluid forces and in the second stage flow through the packed bed/cake is simulated by using the CFD coupled with the discrete element method. Based on the simulations, correlations between the sedimented and the consolidated void fractions are developed. © 2019 American Institute of Chemical Engineers AIChE J, 65: 1294–1303, 2019 相似文献
108.
Anton N. Shuvaev Olga S. Belozor Oleg I. Mozhei Elena D. Khilazheva Andrey N. Shuvaev Yana V. Fritsler S. Kasparov 《International journal of molecular sciences》2021,22(15)
Spinocerebellar ataxias are a family of fatal inherited diseases affecting the brain. Although specific mutated proteins are different, they may have a common pathogenetic mechanism, such as insufficient glutamate clearance. This function fails in reactive glia, leading to excitotoxicity and overactivation of NMDA receptors. Therefore, NMDA receptor blockers could be considered for the management of excitotoxicity. One such drug, memantine, currently used for the treatment of Alzheimer’s disease, could potentially be used for the treatment of other forms of neurodegeneration, for example, spinocerebellar ataxias (SCA). We previously demonstrated close parallels between optogenetically induced cerebellar degeneration and SCA1. Here we induced reactive transformation of cerebellar Bergmann glia (BG) using this novel optogenetic approach and tested whether memantine could counteract changes in BG and Purkinje cell (PC) morphology and expression of the main glial glutamate transporter—excitatory amino acid transporter 1 (EAAT1). Reactive BG induced by chronic optogenetic stimulation presented increased GFAP immunoreactivity, increased thickness and decreased length of its processes. Oral memantine (~90 mg/kg/day for 4 days) prevented thickening of the processes (1.57 to 1.81 vs. 1.62 μm) and strongly antagonized light-induced reduction in their average length (186.0 to 150.8 vs. 171.9 μm). Memantine also prevented the loss of the key glial glutamate transporter EAAT1 on BG. Finally, memantine reduced the loss of PC (4.2 ± 0.2 to 3.2 ± 0.2 vs. 4.1 ± 0.3 cells per 100 μm of the PC layer). These results identify memantine as potential neuroprotective therapeutics for cerebellar ataxias. 相似文献
109.
Zakhar R. Kudrynskyi Xueting Wang Jake Sutcliffe Mahabub A. Bhuiyan Yuhao Fu Zhuo Yang Oleg Makarovsky Laurence Eaves Andrij Solomon Volodymyr T. Maslyuk Zakhar D. Kovalyuk Lijun Zhang Amalia Patan 《Advanced functional materials》2020,30(9)
The design of advanced functional materials with customized properties often requires the use of an alloy. This approach has been used for decades, but only recently to create van der Waals (vdW) alloys for applications in electronics, optoelectronics, and thermoelectrics. A route to engineering their physical properties is by mixing isoelectronic elements, as done for the SnSe2(1?x)S2x alloy. Here, by experiment and first‐principles modeling, it is shown that the value of x can be adjusted over a wide range, indicating good miscibility of the SnS2 and SnSe2 compounds. The x‐dependence of the indirect bandgap energy from Eind = 1.20 eV for SnSe2 to Eind = 2.14 eV for SnS2, corresponds to a large bowing coefficient b ≈ 1 eV, arising from volume deformation and charge exchange effects due to the different sizes and orbital energies of the S‐ and Se‐atoms. This also causes composition‐dependent phonon energy modes, electron–phonon interaction, and temperature dependence of Eind. The alloys are exfoliable into thin layers with properties that depend on the composition, but only weakly on the layer thickness. This work shows that the electronic and vibrational properties of the SnSe2(1?x)S2x alloy and its thin layers provide a versatile platform for development and exploitation. 相似文献
110.
Bin‐Bin Yu Min Liao Yudong Zhu Xusheng Zhang Zheng Du Zhixin Jin Di Liu Yiyu Wang Teresa Gatti Oleg Ageev Zhubing He 《Advanced functional materials》2020,30(24)
As the most promising lead‐free branch, tin halide perovskites suffer from the severe oxidation from Sn2+ to Sn4+, which results in the unsatisfactory conversion efficiency far from what they deserve. In this work, by facile incorporation of methylammonium bromide in composition engineering, formamidinium and methylammonium mixed cations tin halide perovskite films with ultrahighly oriented crystallization are synthesized with the preferential facet of (001), and that oxidation is suppressed with obviously declined trap density. MA+ ions are responsible for that impressive orientation while Br‐ ions account for their bandgap modulation. Depending on high quality of the optimal MA0.25FA0.75SnI2.75Br0.25 perovskite films, their device conversion efficiency surges to 9.31% in contrast to 5.02% of the control formamidinium tin triiodide perovskite (FASnI3) device, along with almost eliminated hysteresis. That also results in the outstanding device stability, maintaining above 80% of the initial efficiency after 300 h of light soaking while the control FASnI3 device fails within 120 h. This paper definitely paves a facile and effective way to develop high‐efficiency tin halide perovskites solar cells, optoelectronic devices, and beyond. 相似文献