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排序方式: 共有633条查询结果,搜索用时 15 毫秒
31.
Jignasu P. Mehta Prashant N. Bhatt Sudhindra N. Misra 《中国稀土学报(英文版)》2006,24(6):648-652
Pr( Ⅲ ) and Nd( Ⅲ ) can be utilized as absorption spectroscopic probes to investigate the interaction of biomolecules like Lysozyme (HEW) with Ca( Ⅱ ) in-vitro ; the most abundant metal ion in the human body system. The spectroscopic techniques involving comparative absorption, absorption difference, and quantitative intensity analysis using 4f-4f transitions are utilized for changes in the inner sphere coordination pattern of Pr( Ⅲ ) and Nd(Ⅲ ) in solution as well as in solid state. The present study deals with an important biomolecule in human metabolism, that is, Lysozyme (HEW). The absorption er-Condon the probab spectral parameters such as the oscillator strength (P), the Judd-Ofelt (Tλ) intensity parameters, and the Slatinter electronic parameters are calculated using chi square methods. The obtained results are used to determine le geometry of the complex in the solution, the nature of the bond between Pr(Ⅲ)/Nd(Ⅲ) with lysozyme, and the inner sphere coordination environment of f-f transitions. The results obtained from various experimental conditions are utilized to investigate the coordination changes in the Pr(Ⅲ)/Nd(Ⅲ) complexes caused by different coordinating sites of lysozyme, normalized bite, denticity, the solvent nature, the coordination number, the nature of bond and other parameters to mimic the interaction of the Ca( Ⅱ ) ion with such biomolecule. 相似文献
32.
Integration – supporting multiple application classes with heterogeneous performance requirements – is an emerging trend
in networks, file systems, and operating systems. We evaluate two architectural alternatives – partitioned and integrated
– for designing next-generation file systems. Whereas a partitioned server employs a separate file system for each application
class, an integrated file server multiplexes its resources among all application classes; we evaluate the performance of the
two architectures with respect to sharing of disk bandwidth among the application classes. We show that although the problem
of sharing disk bandwidth in integrated file systems is conceptually similar to that of sharing network link bandwidth in
integrated services networks, the arguments that demonstrate the superiority of integrated services networks over separate
networks are not applicable to file systems. Furthermore, we show that: an integrated server outperforms the partitioned server
in a large operating region and has slightly worse performance in the remaining region; the capacity of an integrated server
is larger than that of the partitioned server; and an integrated server outperforms the partitioned server by a factor of
up to 6 in the presence of bursty workloads. 相似文献
33.
Various aspects of the mechanical behavior of kaolin clay are discussed in light of experimental observations from a series of strain controlled true triaxial undrained tests performed on cubical kaolin clay specimens with flocculated and dispersed microfabric, using a fully automated flexible boundary experimental setup with real-time feedback control system. The laboratory procedures used to prepare flocculated and dispersed microfabric specimens are presented. Mercury intrusion porosimetry is used to evaluate the pore structure of these specimens. The influence of microfabric on the consolidation behavior of kaolin clay is evaluated based on the data obtained from K0 consolidation during constant rate of strain tests and the isotropic consolidation during true triaxial tests. Undrained tests on kaolin clay show that the following vary with microfabric of specimen: The shear stiffness, excess pore pressure generated during shear, and strength and strain to failure. For both microfabrics, the observed strength behavior using cubical triaxial testing shows a similar pattern of variation with applied stress anisotropy; hence, only a marginal influence of fabric-induced anisotropy. 相似文献
34.
Sohee Kim Prashant Tathireddy Richard A Normann Florian Solzbacher 《IEEE transactions on neural systems and rehabilitation engineering》2007,15(4):493-501
A chronically implantable, wireless neural interface device will require integrating electronic circuitry with the interfacing microelectrodes in order to eliminate wired connections. Since the integrated circuit (IC) dissipates a certain amount of power, it will raise the temperature in surrounding tissues where it is implanted. In this paper, the thermal influence of the integrated 3-D Utah electrode array (UEA) device implanted in the brain was investigated by numerical simulation using finite element analysis (FEA) and by experimental measurement in vitro as well as in vivo. The numerically calculated and experimentally measured temperature increases due to the UEA implantation were in good agreement. The experimentally validated numerical model predicted that the temperature increases linearly with power dissipation through the UEA, with a slope of 0.029 degree C/mW over the power dissipation levels expected to be used. The influences of blood perfusion, brain metabolism, and UEA geometry on tissue heating were also investigated using the numerical model. 相似文献
35.
Approximate dynamic programming (ADP) commonly employs value function approximation to numerically solve complex dynamic programming problems. A statistical perspective of value function approximation employs a design and analysis of computer experiments (DACE) approach, where the “computer experiment” yields points on the value function curve. The DACE approach has been used to numerically solve high-dimensional, continuous-state stochastic dynamic programming, and performs two tasks primarily: (1) design of experiments and (2) statistical modeling. The use of design of experiments enables more efficient discretization. However, identifying the appropriate sample size is not straightforward. Furthermore, identifying the appropriate model structure is a well-known problem in the field of statistics. In this paper, we present a sequential method that can adaptively determine both sample size and model structure. Number-theoretic methods (NTM) are used to sequentially grow the experimental design because of their ability to fill the design space. Feed-forward neural networks (NNs) are used for statistical modeling because of their adjustability in structure-complexity . This adaptive value function approximation (AVFA) method must be automated to enable efficient implementation within ADP. An AVFA algorithm is introduced, that increments the size of the state space training data in each sequential step, and for each sample size a successive model search process is performed to find an optimal NN model. The new algorithm is tested on a nine-dimensional inventory forecasting problem. 相似文献
36.
37.
Nanomechanical properties of indium nanowires like structures fabricated on quartz substrate by trench template technique,
measured using nanoindentation. The hardness and elastic modulus of wires were measured and compared with the values of indium
thin film. Displacement burst observed while indenting the nanowire. ‘Wire-only hardness’ obtained using Korsunsky model from
composite hardness. Nanowires have exhibited almost same modulus as indium thin film but considerable changes were observed
in hardness value. 相似文献
38.
Prashant Singh Pradeep Kumar Anju Katyal Rashmi Kalra Sujata K. Dass Satya Prakash Ramesh Chandra 《Catalysis Letters》2010,134(3-4):303-308
In this present work, we report that phosphotungstic acid provides a simple, efficient and environmentally benign route is a two-component one-pot domino Knoevenagel-type condensation/Michael reaction between 4-coumarin derivative and an aldehyde in water as a solvent in shorter duration with high yields. 相似文献
39.
Additively manufactured polymeric products for automotive, aerospace, and biomedical applications are usually intended for service in an outdoor environment with high mechanical loading conditions. The strength and sustainability of the products can be significantly degraded due to the outdoor environmental conditions such as UV light, moisture, heat, and so forth. In this research work, a novel weather-resistant polymer (WRP) material, that is, acrylonitrile styrene acrylate (ASA), has been studied. Furthermore, this work aims to study the effect of process parameters and enhance the strength of WRP (ASA) specimens using the FFF process. The optimized process parameters, that is, build orientation (BO), extrusion temperature (ET), layer thickness (LT), and printing speed (PS), were identified based on the tensile and flexural strength using the Taguchi technique and statistical analysis. The best tensile and flexural strengths for the specimen were achieved at both orientations (XYZ and ZXY) TS: 255°C ET, 0.14 mm LT, 50 mm/s PS; and FS: 245°C ET, 0.28 mm LT, 50 mm/s PS, respectively. Regression model was developed to investigate the correlation between the process parameters with tensile and flexural strength. A validation test confirmed the findings, and the error between the actual and predicted values is less than ±10%. 相似文献
40.
In this paper, a Lateral Trench Oxide Schottky (LTOS) rectifier on silicon-on-insulator suitable for power integrated circuits is presented. The proposed structure utilizes a surface Schottky contact with vertical field-plate placed in a trench filled with oxide. The field-plate reduces the electric field on the Schottky contact and suppresses the barrier lowering effect leading to significant improvement in the device performance. Further, the proposed structure folds the drift region in vertical and horizontal directions resulting substantial reduction in pitch length of the device. Two-dimensional numerical simulations have been performed to analyse and optimize the performance of proposed device and results are compared with that of the conventional lateral Schottky rectifier. The LTOS rectifier provides 60 % improvement in breakdown voltage and 50 % reduction in pitch length as compared to the conventional device while maintaining low forward voltage drop and low reverse leakage current. 相似文献