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41.
42.
J. Török S. Krishnamurthy J. Kertész S. Roux 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,18(4):697-701
We introduce a model for the slow relaxation of an energy landscape caused by its local interaction with a random walker whose
motion is dictated by the landscape itself. By choosing relevant measures of time and potential this self-quenched dynamics can be mapped on to the “True” Self-Avoiding Walk model. This correspondence reveals that the average distance of
the walker at time t from its starting point is , where for one dimension and 1/2 for all higher dimensions. Furthermore, the evolution of the landscape is similar to that in growth
models with extremal dynamics.
Received 8 August 2000 相似文献
43.
Neha Sharma Bipin K. Srivastava Anjali Krishnamurthy A.K. Nigam 《Solid State Sciences》2010,12(8):1464-1468
Magnetic behaviour of the perovskite La0.5Gd0.5CrO3 has been studied. The orthochromite orders canted antiferromagnetically below Neel temperature TN of ~225 K. Reversal of magnetization is observed in temperature dependence of magnetization measured in field cooled mode under external fields upto 500 Oe. In the field dependence of magnetization below TN, a small hysteresis is observed with the magnetic anisotropy continuously increasing with lowering of temperature. Estimated values of Cr3+ moments, internal field due to sub-lattice of canted ordered Cr3+ and the paramagnetic Curie temperature of Gd3+ sub-lattice are found to be smaller than reported for GdCrO3. Compared with Pr substituted analogue La0.5Pr0.5CrO3, Cr3+ moment is about the same but the internal field at the Gd3+ sub-lattice is much smaller. 相似文献
44.
An improvement to the interacting multiple model (IMM) algorithm 总被引:10,自引:0,他引:10
Computing the optimal conditional mean state estimate for a jump Markov linear system requires exponential complexity, and hence, practical filtering algorithms are necessarily suboptimal. In the target tracking literature, suboptimal multiple-model filtering algorithms, such as the interacting multiple model (IMM) method and generalized pseudo-Bayesian (GPB) schemes, are widely used for state estimation of such systems. We derive a reweighted interacting multiple model algorithm. Although the IMM algorithm is an approximation of the conditional mean state estimator, our algorithm is a recursive implementation of a maximum a posteriori (MAP) state sequence estimator. This MAP estimator is an instance of a previous version of the EM algorithm known as the alternating expectation conditional maximization (AECM) algorithm. Computer simulations indicate that the proposed reweighted IMM algorithm is a competitive alternative to the popular IMM algorithm and GPB methods 相似文献
45.
R. Murugavel G. Anantharaman D. Krishnamurthy M. Sathiyendiran M. G. Walawalkar 《Journal of Chemical Sciences》2000,112(3):273-290
This article describes the recent results obtained in our laboratory on the interaction of polyfunctional ligands with divalent
alkaline earth metal ions and a few divalent transition metal ions. Treatment of MC12·nH2O (M = Mg, Ca, Sr or Ba) with 2-amino benzoic acid leads to the formation of complexes [Mg(2-aba)2] (1), [Ca(2-aba)2(OH2)3]∞ (2), [Sr(2-aba)2(OH2)2
2·H2O)]∞ (3), [Ba(2-aba)2(OH2)]∞ (4), respectively. While the calcium ions in2 are hepta-coordinated, the strontium and barium ions in3 and4 reveal a coordination number of nine apart from additional metal-metal interactions. Apart from the carboxylate functionality,
the amino group also binds to the metal centres in the case of strontium and barium complexes3 and4. Complexes [Mg(H2O)6(4-aba)2·2H2O] (5), [Ca(4-aba)2(H2O)2] (6) prepared from 4-aminobenzoic acid reveal more open or layered structures. Interaction of 2-mercaptobenzoic acid with MCl2·6H2O (M = Mg, Ca), however, leads to the oxidation of the thiol group resulting in the disulphide 2,2′ -dithiobis(benzoic acid).
New metal-organic framework based hydrogen-bonded porous solids [M(btec) (OH2)4
n·n(C4H12N2)·4nH2O] (btec = 1,2,4,5-benzene tetracarboxylate) (M = Co9; Ni10; Zn11) have been synthesized from 1,2,4,5-benzene tetracarboxylic acid in the presence of piperazine. These compounds are made up
of extensively hydrogen-bonded alternating layers of anionic M-btec co-ordination polymer and piperazinium cations. Compounds2- 11 described herein form polymeric networks in the solid-state with the aid of different coordinating capabilities of the carboxylate
anions hydrogen bonding interactions. 相似文献
46.
Wenjun Tang Dr. Andrew G. Capacci Xudong Wei Dr. Wenjie Li Dr. Andre White Dr. Nitinchandra D. Patel Jolaine Savoie Joe J. Gao Sonia Rodriguez Dr. Bo Qu Dr. Nizar Haddad Dr. Bruce Z. Lu Dr. Dhileepkumar Krishnamurthy Dr. Nathan K. Yee Dr. Chris H. Senanayake Dr. 《Angewandte Chemie (International ed. in English)》2010,49(34):5879-5883
47.
Pukar Malla Hasnain Lakdawala Ravi Naiknaware Krishnamurthy Soumyanath Kevin Kornegay 《Analog Integrated Circuits and Signal Processing》2010,65(2):197-208
Modern multi-standard receivers in deep-submicron technologies pose significant design challenges on the analog baseband.
Moving this analog filtering to the digital domain simplifies the design, yielding a process-scalable implementation. However,
analog-to-digital converter (ADC) specifications now become more stringent and must be obtained by comprehending the standard
and the system. Assuming a receiver NF of 5.96 dB and SNR degradation of 0.36 dB by the ADC, the proposed dual-mode WiFi/WiMAX
receiver attains an input sensitivity of −74 dBm (20 MHz channel bandwidth). To accommodate the high dynamic range and the
anti-alias rejection needed for the system, a Delta-Sigma (ΔΣ) ADC is proposed. Single-loop and Multi-Stage Noise-Shaping
(MASH) architectures that achieve a SNR of 69 dB at a low oversampling ratio (OSR) of 8 for a conversion bandwidth of 40 MHz
(108 Mbps, OFDM) are investigated at system level. Based on thermal noise, harmonic distortion, and power tradeoffs, a ΔΣ
ADC design that meets the design specifications is presented. 相似文献
48.
Trushar Gohil Robert H. P. McGregor Dominik Szczerba Kathrin Burckhardt Krishnamurthy Muralidhar Gábor Székely 《国际流体数值方法杂志》2011,66(8):1037-1067
Cardiovascular diseases are one of the major causes of long‐term morbidity and mortality in human beings. The nearly epidemic increase in prevalence of such diseases poses a serious threat to public health and calls for efficient methods of diagnosis and treatment. Non‐invasive diagnostic procedures such as MRI are often used in this context; however, these are limited in terms of spatial and temporal resolution and do not provide information on time‐dependent pressures and wall shear stresses—key quantities considered to be partially responsible for the formation and development of related pathologies. The present study is concerned with the numerical simulation of oscillatory flow through the abdominal aortic bifurcation. Computational fluid dynamics simulation of oscillatory flow in a branched geometry at high Reynolds numbers poses considerable challenges. The present study reports a detailed comparison of simulations performed with a finite volume and a finite element method, two approaches with significant differences in their discretization strategy, treatment of boundary conditions and other numerical aspects. Both solvers were parallelized, using loop parallelization of the BiCGStab linear solver for the finite volume and domain decomposition based on the Schur complement method for the finite element technique. The experience gained with these two approaches for the solution of flow in a bifurcation forms the focus of this study. Although similar results were obtained for both methods, the computation time required for convergence was found to be significantly smaller for the finite element approach. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
49.
Microdroplets of 15-μm diameter are subjected to ultra-short laser pulses of intensities up to 1015Wcm−2 to produce hot dense plasma. The hot electrons produced in the microdroplet plasma result in efficient generation of hard X-rays in the range 50–150keV at an irradiance as low as 8×1014Wcm−2. The X-ray source efficiency is estimated to be about 2 ×10−7%. A prepulse that is about 11ns ahead of the main pulse strongly influences the droplet plasma and the resulting X-ray emission. For a similar laser prepulse and intensity, no measurable hard X-ray emission is observed when the laser is focused on a solid target of similar composition and this indicates that liquid droplet targets are best suited for hard X-ray generation in laser–plasma interactions. 相似文献
50.
Stochastic gradient algorithms for design of minimum error-rate linear dispersion codes in MIMO wireless systems 总被引:1,自引:0,他引:1
Xiaodong Wang Krishnamurthy V. Jibing Wang 《Signal Processing, IEEE Transactions on》2006,54(4):1242-1255
Linear dispersion (LD) codes are a good candidate for high-data-rate multiple-input multiple-ouput (MIMO) signaling. Traditionally LD codes were designed by maximizing the average mutual information, which cannot guarantee good error performance. This paper presents a new design scheme for LD codes that directly minimizes the block error rate (BLER) in MIMO channels with arbitrary fading statistics and various detection algorithms. For MIMO systems employing LD codes, the error rate does not admit an explicit form. Therefore, we cannot use deterministic optimization methods to design the minimum-error-rate LD codes. In this paper, we propose a simulation-based optimization methodology for the design of LD codes through stochastic approximation and simulation-based gradient estimation. The gradient estimation is done using the score function method originally developed in the discrete-event-system community. The proposed method can be applied to design the minimum-error-rate LD codes for a variety of detector structures including the maximum-likelihood (ML) detector and several suboptimal detectors. It can also design optimal codes under arbitrary fading channel statistics; in particular, it can take into account the knowledge of spatial fading correlation at the transmitter and receiver ends. Simulation results show that codes generated by the proposed new design paradigm generally outperform the codes designed based on algebraic number theory. 相似文献