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31.
Yeonjong Koo Ekaterina Y. Lukianova‐Hleb Joann Pan Sean M. Thompson Dmitri O. Lapotko Janet Braam 《Small (Weinheim an der Bergstrasse, Germany)》2016,12(5):623-630
Biological responses to photothermal effects of gold nanoparticles (GNPs) have been demonstrated and employed for various applications in diverse systems except for one important class – plants. Here, the uptake of GNPs through Arabidopsis thaliana roots and translocation to leaves are reported. Successful plasmonic nanobubble generation and acoustic signal detection in planta is demonstrated. Furthermore, Arabidopsis leaves harboring GNPs and exposed to continuous laser or noncoherent light show elevated temperatures across the leaf surface and induced expression of heat‐shock regulated genes. Overall, these results demonstrate that Arabidopsis can readily take up GNPs through the roots and translocate the particles to leaf tissues. Once within leaves, GNPs can act as photothermal agents for on‐demand remote activation of localized biological processes in plants. 相似文献
32.
Virus Matryoshka: A Bacteriophage Particle—Guided Molecular Assembly Approach to a Monodisperse Model of the Immature Human Immunodeficiency Virus 下载免费PDF全文
Pooja Saxena Li He Andrey Malyutin Siddhartha A. K. Datta Alan Rein Kevin M. Bond Martin F. Jarrold Alessandro Spilotros Dmitri Svergun Trevor Douglas Bogdan Dragnea 《Small (Weinheim an der Bergstrasse, Germany)》2016,12(42):5862-5872
Immature human immunodeficiency virus type 1 (HIV‐1) is approximately spherical, but is constructed from a hexagonal lattice of the Gag protein. As a hexagonal lattice is necessarily flat, the local symmetry cannot be maintained throughout the structure. This geometrical frustration presumably results in bending stress. In natural particles, the stress is relieved by incorporation of packing defects, but the magnitude of this stress and its significance for the particles is not known. In order to control this stress, we have now assembled the Gag protein on a quasi‐spherical template derived from bacteriophage P22. This template is monodisperse in size and electron‐transparent, enabling the use of cryo‐electron microscopy in structural studies. These templated assemblies are far less polydisperse than any previously described virus‐like particles (and, while constructed according to the same lattice as natural particles, contain almost no packing defects). This system gives us the ability to study the relationship between packing defects, curvature and elastic energy, and thermodynamic stability. As Gag is bound to the P22 template by single‐stranded DNA, treatment of the particles with DNase enabled us to determine the intrinsic radius of curvature of a Gag lattice, unconstrained by DNA or a template. We found that this intrinsic radius is far larger than that of a virion or P22‐templated particle. We conclude that Gag is under elastic strain in a particle; this has important implications for the kinetics of shell growth, the stability of the shell, and the type of defects it will assume as it grows. 相似文献
33.
The effect of traffic distribution on communication rates and receiver complexity in ad-hoc networks is addressed, considering
a network with constant density of users and a certain traffic model. Information theoretic upper bounds on communication
rates are derived under an assumption that transmitting nodes as well as receiving nodes cooperate. It is shown that for the
case of large signal attenuation the bounds hold even when the cooperation among users is limited to a certain region of the
network domain. Furthermore, achievability bounds on communication rates are derived. The bounds rely on two proposed local
cooperation strategies. A comparison shows that the upper bounds are tight and closely follow the achievability results. Finally,
the impact of traffic localization on the receiver complexity is addressed. 相似文献
34.
Dmitri Muraviev 《溶剂提取与离子交换》2013,31(4):753-778
ABSTRACT This paper describes new perspectives for the development and wider application of extraction and ion-exchange chromatography for separation of metal ion mixtures. The stabilization of extraction chromatographic materials by different techniques, the evaluation of changes in the behaviour of immobilized reagents (extractants or water-soluble ligands) as compared to those in their “free” state, and the combination of extraction and ion-exchange within one fractionation technique are considered and discussed along with some related problems. 相似文献
35.
Using a single mode 915 MHz applicator, we fabricate novel Cu50Zr45Al5 metallic glass/polyphenylene sulfide (PPS) composites with high relative densities by microwave processing the constituents in a separated H-field with an applied pressure of about 5 MPa. The heating behaviors and structural changes of the composites have been investigated. A good bonding state between metallic glassy and PPS particles is found. The gradient structure is also induced by microwave heating of the composites with a high fraction of PPS phase. 相似文献
36.
Dmitri V. Malakhov Xing Jun Liu Ikuo Ohnuma Kiyohito Ishida 《Journal of Phase Equilibria》2000,21(6):514-520
A thermodynamic assessment of the Bi-Sn-Zn ternary system was carried out by considering the experimental data including the phase equilibria and thermodynamic properties on the basis of the CALPHAD method. A set of optimized thermodynamic parameters has been obtained, which leads to a very good fit between calculation and experiments. In particular, the thermodynamic calculations in the Sn-rich portion are presented in view of the recent progress in Pb-free solder alloys. 相似文献
37.
Zineb Felfli Amanda R. Eure Dmitri Sokolovski 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2010,268(9):1370-1052
Electron elastic total cross sections (TCSs) and differential cross sections (DCSs) in both impact energy and scattering angle for the excited Au and Pt atoms are calculated in the electron impact energy range 0 ? E ? 4.0 eV. The cross sections are found to be characterized by very sharp long-lived resonances whose positions are identified with the binding energies of the excited anions formed during the collisions. The recent novel Regge-pole methodology wherein is embedded through the Mulholland formula the electron-electron correlations is used together with a Thomas-Fermi type potential incorporating the crucial core-polarization interaction for the calculations of the TCSs. The DCSs are evaluated using a partial wave expansion. The Ramsauer-Townsend minima, the shape resonances and the binding energies of the excited Au− and Pt− anions are extracted from the cross sections, while the critical minima are determined from the DCSs. 相似文献
38.
Dmitri V. Louzguine-Luzgin Alain R. Yavari Gavin Vaughan Akihisa Inoue 《Intermetallics》2009,17(7):477-480
This paper presents some crystalline structures which can be taken as the approximants of the corresponding metallic glassy phases. Such phases have a clustered structure and preferably (but not strictly necessarily) a large unit cell. Peak intensities of their radial distribution functions (RDFs) must be integrated at a step of about 0.01 nm in order to obtain RDFs similar to those of the corresponding glassy alloys owing to a degree of disorder related to the corresponding glassy structures. 相似文献
39.
The effect of Fe3+ concentration on saturation magnetic flux density (Bs) of electrodeposited Co40-44Fe60-56 films was investigated. The results show that if the conditions at the electrochemical interface for nucleation/precipitation of iron(III) hydroxide (Fe(OH)3) are reached, the Bs of electrodeposited Co40-44Fe60-56 films quickly decreases as a result of the Fe(OH)3 incorporation into deposit. These conditions are discussed as a function of the solution formulation (pH) and the parameters of electrodeposition process (current density, current efficiency, diffusion layer thickness) and a simple analytical model is developed qualitatively describing the hydroxide incorporation phenomenon and resulting decrease in Bs of Co40-44Fe60-56 films. 相似文献
40.
Providing reliable data communications over wireless channels is a challenging task because time-varying wireless channel
characteristics often lead to bit errors. These errors result in loss of IP packets and, consequently, TCP segments encapsulated
into these packets. Since TCP cannot distinguish packet losses due to bit corruption from those due to network congestion,
any packet loss caused by wireless channel impairments leads to unnecessary execution of the TCP congestion control algorithms
and, hence, sub-optimal performance. Automatic Repeat reQuest (ARQ) and Forward Error Correction (FEC) try to improve communication
reliability and reduce packet losses by detecting and recovering corrupted bits. Most analytical models that studied the effect
of ARQ and FEC on TCP performance assumed that the ARQ scheme is perfectly persistent (i.e., completely reliable), thus a
frame is always successfully transmitted irrespective of the number of transmission attempts it takes. In this paper, we develop
an analytical cross-layer model for a TCP connection running over a wireless channel with a semi-reliable ARQ scheme, where
the amount of transmission attempts is limited by some number. The model allows to evaluate the joint effect of stochastic
properties of the wireless channel characteristics and various implementation-specific parameters on TCP performance, which
makes it suitable for performance optimization studies. The input parameters include the bit error rate, the value of the
normalized autocorrelation function of bit error observations at lag 1, the strength of the FEC code, the persistency of ARQ,
the size of protocol data units at different layers, the raw data rate of the wireless channel, and the bottleneck link buffer
size. 相似文献