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101.
The method of cosine pattern synthesis for single- and multiple-main-beam equispaced linear arrays is introduced. The cosine pattern function is characterized by the position of the main beam in the &thetas;-domain and its half-power beamwidth. The Fourier series and Woodward-Lawson methods are applied to the special cases of single- or multiple-main-beam cosine pattern synthesis. The patterns produced by application of these classical shaped-beam synthesis methods can then be used as initial patterns for iterative and perturbational techniques. Examples are presented and discussed, including the use of multiple-main-beam cosine pattern synthesis to design a high-power, high-frequency, ground-based transmitter for the creation of an array of `wireless' ionospheric dipoles 相似文献
102.
Patrick J. Fricke Jenna L. Stasko Dylan T. Robbins Alexander C. Gardner Jacqueline Stash Mark J. Ferraro Michael W. Fennie 《Tetrahedron letters》2017,58(48):4510-4513
Propargyl imidates derived from aromatic and aliphatic nitriles cyclize at room temperature in high yields when treated with a catalytic amount of copper (I) iodide. This 5-exo-dig process affords dihydrooxazoles which do not aromatize under the reaction conditions, and which are isolated without chromatography. Investigations of the reaction scope, subsequent functionalization of the reaction products, and preliminary mechanistic data are presented. 相似文献
103.
Pietro Lura Frank Winnefeld Stefanie Klemm 《Journal of Thermal Analysis and Calorimetry》2010,101(3):925-932
Isothermal calorimetry and chemical shrinkage measurements are two independent techniques used to study the development of
hydration in cementitious systems. In this study, calorimetry and chemical shrinkage measurements were combined and simultaneously
performed on hydrating cement paste samples. Portland cement pastes with different water to cement ratios and a cement paste
containing calcium sulfoaluminate clinker and anhydrite were studied. The combined calorimetry/chemical shrinkage test showed
good reproducibility and revealed the different hydration behavior of sealed samples and open samples, i.e., samples exposed
to external water during hydration. Large differences between sealed and open samples were observed in a Portland cement paste
with low water to cement ratio and in the calcium sulfoaluminate paste; these effects are attributed to self-desiccation of
the sealed pastes. Once the setup is fully automatized, it is expected that combined calorimetry/chemical shrinkage measurements
can be routinely used for investigating cement hydration. 相似文献
104.
105.
Cali F Ragalmuto A Chiavetta V Calabrese G Fichera M Vinci M Ruggeri G Schinocca P Sturnio M Romano S Romano V Elia M 《Experimental & molecular medicine》2010,42(12):842-848
Angelman syndrome (AS) is a severe neurobehavioural disorder caused by failure of expression of the maternal copy of the imprinted domain located on 15q11-q13. There are different mechanisms leading to AS: maternal microdeletion, uniparental disomy, defects in a putative imprinting centre, mutations of the E3 ubiquitin protein ligase (UBE3A) gene. However, some of suspected cases of AS are still scored negative to all the latter mutations. Recently, it has been shown that a proportion of negative cases bear large deletions overlapping one or more exons of the UBE3A gene. These deletions are difficult to detect by conventional gene-scanning methods due to the masking effect by the non-deleted allele. In this study, we have used for the first time multiplex ligation-dependent probe amplification (MLPA) and comparative multiplex dosage analysis (CMDA) to search for large deletions affecting the UBE3A gene. Using this approach, we identified a novel causative deletion involving exon 8 in an affected sibling. Based on our results, we propose the use of MLPA as a fast, accurate and inexpensive test to detect large deletions in the UBE3A gene in a small but significant percentage of AS patients. 相似文献
106.
Xiaofeng Lu Fletcher D. Wicker Don Towsley Zhang Xiong Pietro Lio’ 《Wireless Personal Communications》2010,55(1):51-63
This paper studies the problem of detection of directional antennas and omni-directional antennas by hostile detection systems.
We present a model for calculating the probability of detecting a transmitter at arbitrary location around the transmitter.
Our study shows that, if a directional antenna employs the same transmit power as an omni-directional antenna, the directional
antenna can not decrease the probability of being detected. In some scenarios, a directional antenna is more likely to be
detected than an omni-directional antenna. However, if a directional antenna provides the same Effective Isotropic Radiated
Power in the direction of the receiver as an omni-directional antenna, the transmit power needed by a directional antenna
to send data is much less than that of an omni-directional antenna. In this scenario, the probability of detecting a directional
antenna is reduced by over 90%. This reveals that directional antennas can be used to build a secure path to send data at
low probability of being detected by adversaries. 相似文献
107.
The searching and recovering of the correct reconstruction distance in digital holography (DH) can be a cumbersome and subjective procedure. Here we report on an algorithm for automatically estimating the in-focus image and recovering the correct reconstruction distance for speckle holograms. We have tested the approach in determining the reconstruction distances of stretched digital holograms. Stretching a hologram with a variable elongation parameter makes it possible to change the in-focus distance of the reconstructed image. In this way, the proposed algorithm can be verified at different distances by dispensing the recording of different holograms. Experimental results are shown with the aim of demonstrating the usefulness of the proposed method, and a comparative analysis has been performed with respect to other existing algorithms developed for DH. 相似文献
108.
109.
110.
We prove the existence of small amplitude quasi-periodic solutions for quasi-linear and fully nonlinear forced perturbations of the linear Airy equation. For Hamiltonian or reversible nonlinearities we also prove their linear stability. The key analysis concerns the reducibility of the linearized operator at an approximate solution, which provides a sharp asymptotic expansion of its eigenvalues. For quasi-linear perturbations this cannot be directly obtained by a KAM iteration. Hence we first perform a regularization procedure, which conjugates the linearized operator to an operator with constant coefficients plus a bounded remainder. These transformations are obtained by changes of variables induced by diffeomorphisms of the torus and pseudo-differential operators. At this point we implement a Nash–Moser iteration (with second order Melnikov non-resonance conditions) which completes the reduction to constant coefficients. 相似文献