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排序方式: 共有806条查询结果,搜索用时 78 毫秒
71.
D. J. Davidson S. S. Sai Raman M. V. Lototsky O. N. Srivastava 《International Journal of Hydrogen Energy》2003,28(12):1425-1431
This paper deals with computer simulation of the P–C isotherms of some ZrFe2 type (Zr(Fe1−xCrx)2, Zr1−xTixFe1.4Cr0.6, Zr1−2xMmxTixFe1.4Cr0.6 : x00.4) of hydrogen storage materials. A feasible mathematical model has been developed to simulate the P–C isotherms. The randomized variables in the model applied for simulating the P–C isotherms of the above-mentioned ZrFe2 type hydrogen storage materials correspond to change in enthalpy (ΔH) and entropy (ΔS) of hydride formation. Several ZrFe2 type materials as in above have been synthesized and their P–C isotherms, enthalpy and entropy change has been evaluated experimentally in order to have input data for simulation. A special software was developed to simulate the P–C isotherms using the said model. A close match between the experimentally observed and simulated P–C isotherms for the above said ZrFe2 type alloys has been obtained. 相似文献
72.
Sashikala Somasundaram C. Raman Nair Chenthamarakshan Norma R. de Tacconi Krishnan Rajeshwar 《International Journal of Hydrogen Energy》2007,32(18):4661-4669
A new approach to combining a p-type semiconductor photocathode with sacrificial electron donors in the anode compartment in a two-compartment cell is described for photocatalytic hydrogen production. This approach is demonstrated for electrodeposited p-Cu2O film supported on a transparent conducting oxide substrate. The oxide semiconductor surface was photochemically modified in situ with an ultra-thin Ni layer prior to use. A variety of organic and organometallic electron donors was screened by cyclic voltammetry, and the optimal candidate was hydroquinone at pH 10. Importantly, no photocurrents were measured at zero bias voltage in the two-compartment cell in the absence of an electron donor, signaling that water photosplitting is not feasible with p-Cu2O. Methyl viologen (MV2+) was effective as an electron relay in the photocathode chamber as shown by in situ spectroscopic monitoring of the MV+ radical cations. Finally, practical perspectives of this new approach and value-added options for combining it with pollutant destruction are described. 相似文献
73.
Results of experimental measurements of emissivity carried out on cobalt oxide and nickel sulphide films deposited on aluminum substrates are reported in this paper. Experimental results supported the general behaviour of variation of emissivity with film thickness as reported theoretically. The theoretical model is based on the interaction and attenuation of the emitted wavelengths from the substrate and film materials. 相似文献
74.
Modelling of mode-I stable crack growth under hydrogen assisted stress corrosion cracking 总被引:1,自引:0,他引:1
The paper presents a new strategy based on combined analytical and finite element (FE) solution to hydrogen assisted stress corrosion crack growth. The diffusion process is solved analytically through both one-and two-dimensional modelling. These solutions are adopted with two-dimensional FE based cohesive zone model of crack extension study. The results fit well with published experimental data and show improvement over the predictions by full FE approach. The new solution approach helps to reduce time required for simulation/computation. The study has produced a relationship between concentration dependent reduction in cohesive strength and plastic strain rate. 相似文献
75.
The essence of the modern hashing technique in computer science is the derivation of a number from a nonnumeric key to index into a table where the record containing the key is stored. In this paper, an interestingly similar technique used in South Indian musicology in the 18th century is described, and the question of whether it is an anticipation of the hashing technique is briefly addressed. The problem of retrieving a record from a table based upon a given key has been studied extensively. In this paper, I describe one particular approach to this problem-hashing-and also an interesting earlier development very similar to it. It is generally believed that the idea of hashing was originated by H.P. Luhn (1953), and first described in the open literature by A.I. Dumey (1956), but is it possible that the Katapayadi scheme of deriving numbers from names-in conjunction with the applications to which it had been put, especially in classical South Indian musicology-is an early anticipation of the hashing technique? I discuss this issue in detail in this paper 相似文献
76.
Raman S. Patnaik L.M. 《Very Large Scale Integration (VLSI) Systems, IEEE Transactions on》1996,4(4):434-444
We present a novel genetic algorithm-based partitioning scheme for multichip modules (MCM's) which integrates four performance constraints simultaneously: pin count, area, heat dissipation, and timing. We also present a similar partitioning algorithm based on evolutionary programming. Experimental studies demonstrate the superiority of these methods over deterministic Fiduccia-Mattheyes (FM) algorithm and simulated annealing (SA) technique. Our approach performs better than another genetic algorithm-based method recently reported. The adaptive change of crossover and mutation probabilities results in better convergence of the partitioning algorithm 相似文献
77.
A component-level study has revealed that the durability of magnetic hard disks coated with Z-dol improved with increasing level of relative humidity, while the durability of disks coated with Z-tetraol was generally superior and not affected by the humidity within the range investigated (8–80%). It has been shown earlier that water molecules effectively passivate the catalytic centers responsible for the lubricant degradation. The Z-dol molecular chain has a hydroxyl group at each end, while the Z-tetraol molecular chain has two hydroxyl groups at each end. Having surmised that the superior performance of Z-tetraol can be ascribed to its ability to retain water molecules at its multiply hydroxylated ends, the solubility of water in Z-dol, Z-tetraol, and Z-TX were investigated using proton NMR spectroscopy. The study revealed that Z-tetraol is not only able to retain a much larger number of water molecules at its ends, but also is able to form stronger hydrogen bonds. Z-tetraol would then bond more tightly to the carbon overcoat (via hydrogen bonding with the surface hydroxyl groups), and be more resistant against catalytic degradation owing to its affinity to, and retention of water molecules. 相似文献
78.
Computing hierarchical curve-skeletons of 3D objects 总被引:6,自引:0,他引:6
Nicu D. Cornea Deborah Silver Xiaosong Yuan Raman Balasubramanian 《The Visual computer》2005,21(11):945-955
A curve-skeleton of a 3D object is a stick-like figure or centerline representation of that object. It is used for diverse
applications, including virtual colonoscopy and animation. In this paper, we introduce the concept of hierarchical curve-skeletons
and describe a general and robust methodology that computes a family of increasingly detailed curve-skeletons. The algorithm
is based upon computing a repulsive force field over a discretization of the 3D object and using topological characteristics
of the resulting vector field, such as critical points and critical curves, to extract the curve-skeleton. We demonstrate
this method on many different types of 3D objects (volumetric, polygonal and scattered point sets) and discuss various extensions
of this approach. 相似文献
79.
Ercan Balikci A. Raman R. A. Mirshams 《Metallurgical and Materials Transactions A》1997,28(10):1993-2003
IN738LC is a modern, nickel-based superalloy utilized at high temperatures in aggressive environments. Durability of this
superalloy is dependent on the strengthening of γ′ precipitates. This study focuses on the microstructural development of IN738LC during various heat treatments. The 1120
°C/2 h/accelerated air-cooled (AAC) solution treatment, given in the literature, already produces a bimodal precipitate microstructure,
which is, thus, not an adequate solutionizing procedure to yield a single-phase solid solution in the alloy at the outset.
However, the 1235 °C/4 h/water quenched (WQ) solution treatment does produce the single-phase condition. A microstructure
with fine precipitates develops if solutionizing is carried out under 1200 °C/4 h/AAC conditions. Agings at lower temperatures
after 1200 °C/4 h/AAC or 1250 °C/4 h/AAC or WQ conditions yield analogous microstructures. Agings below ∼950 °C for 24 hours
yield nearly spheroidal precipitates, and single aging for 24 hours at 1050 °C or 1120 °C produces cuboidal precipitates.
Two different γ′ precipitate growth processes are observed: merging of smaller precipitates to produce larger ones (in duplex precipitate-size
microstructures) and growth through solute absorption from the matrix. Average activation energies for the precipitate growth
processes are 191 and 350 kJ/mol in the ranges of 850 °C to 1050 °C and 1050 °C to 1120 °C, respectively, calculated using
the precipitate sizes from microstructures in the WQ condition, and 150 and 298 kJ/mol in the analogous temperature ranges,
calculated from precipitate sizes in the microstructures in the slow furnace-cooled condition. 相似文献
80.
Murali Raman 《Information Systems Management》2006,23(4):59-66
This article provides a brief tutorial of Wiki technology as a collaborative tool. A case example from a university administration context suggests that - like many other end-user technologies - training and support needs should be carefully considered before the potential value of using this “free” technology to support knowledge management efforts can be satisfactorily realized. 相似文献