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141.
Carbon Nanodot‐Sensitized Modulation of Alzheimer's β‐Amyloid Self‐Assembly,Disassembly, and Toxicity 下载免费PDF全文
You Jung Chung Kayoung Kim Byung Il Lee Chan Beum Park 《Small (Weinheim an der Bergstrasse, Germany)》2017,13(34)
The self‐assembly of amyloidogenic peptides into β‐sheet‐rich aggregates is a general feature of many neurodegenerative diseases, including Alzheimer's disease, which signifies the need for the effective attenuation of amyloid aggregation toward alleviating amyloid‐associated neurotoxicity. This study reports that photoluminescent carbon nanodots (CDs) can effectively suppress Alzheimer's β‐amyloid (Aβ) self‐assembly and function as a β‐sheet breaker disintegrating preformed Aβ aggregates. This study synthesizes CDs using ammonium citrate through one‐pot hydrothermal treatment and passivates their surface with branched polyethylenimine (bPEI). The bPEI‐coated CDs (bPEI@CDs) exhibit hydrophilic and cationic surface characteristics, which interact with the negatively charged residues of Aβ peptides, suppressing the aggregation of Aβ peptides. Under light illumination, bPEI@CDs display a more pronounced effect on Aβ aggregation and on the dissociation of β‐sheet‐rich assemblies through the generation of reactive oxygen species from photoactivated bPEI@CDs. The light‐triggered attenuation effect of Aβ aggregation using a series of experiments, including photochemical and microscopic analysis, is verified. Furthermore, the cell viability test confirms the ability of photoactivated bPEI@CDs for the suppression of Aβ‐mediated cytotoxicity, indicating bPEI@CDs' potency as an effective anti‐Aβ neurotoxin agent. 相似文献
142.
Ji Chan Park Shin Wook Kang Jeong-Chul Kim Jae In Kwon Sanha Jang Geun Bae Rhim Mijong Kim Dong Hyun Chun Ho-Tae Lee Heon Jung Hyunjoon Song Jung-II Yang 《Nano Research》2017,(3):1044-1055
A cobalt-silica hybrid nanocatalyst bearing small cobalt particles of diameter ~5 nm was prepared through a hydrothermal reaction and hydrogen reduction.The resulting material showed very high CO conversion (>82%) and high hydrocarbon productivity (~1.0 gHc·g-1cat,·h-11) with high activity (~8.5 x 10-5 molco·g-1Co·S-1) in the Fischer-Tropsch synthesis reaction. 相似文献
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146.
To understand the entrainment process in granular flow, numerical experiments have been conducted using a Discrete Element Method model. A flow channel of 8 m long with \(15^\circ \) slope is setup with monitoring points located in an erodible bed. Particles, ranging from 3 to 4 mm in diameters, are used in the simulations. In the simulations, translational, rotational and average velocities, total volume, shear stresses are calculated in the measurement circles. The sizes of the measurement circles have been varied to see their effects on the results. It is found the minimum size of the measurement circles should include 20–30 particles. An new analytical model has been developed to calculate entrainment in granular flow. Results of the numerical experiment are compared with analytical model. Shear stresses at the interface between flowing particles in motion and the immobile particles in the channel bed, change of depth of erosion and entrainment rate are used to verify the analytical model. It is found that the calculated shear stresses in the PFC model agree well with the shear stresses calculated using Mohr–Coulomb frictional relationship in the analytical model. The calculated depth of erosion using the new analytical model is also compared with that from dynamic and static entrainment model. The results indicates that the analytical model is able to capture the mechanism of erosion and it can be used in granular flow analysis. 相似文献
147.
We present a robust optimization framework that is applicable to general nonlinear programs (NLP) with uncertain parameters. We focus on design problems with partial differential equations (PDE), which involve high computational cost. Our framework addresses the uncertainty with a deterministic worst-case approach. Since the resulting min–max problem is computationally intractable, we propose an approximate robust formulation that employs quadratic models of the involved functions that can be handled efficiently with standard NLP solvers. We outline numerical methods to build the quadratic models, compute their derivatives, and deal with high-dimensional uncertainties. We apply the presented approach to the parametrized shape optimization of systems that are governed by different kinds of PDE and present numerical results. 相似文献
148.
Herein, hierarchically structured SnO2 microspheres are designed and synthesized as an efficient anode material for lithium-ion batteries using hollow SnO2 nanoplates. Three-dimensionally ordered macroporous (3-DOM) SnO x -C microspheres synthesized by spray pyrolysis are transformed into hierarchically structured SnO2 microspheres by a two-step post-treatment process. Sulfidation produces hierarchically structured SnS-SnS2-C microspheres comprising tin sulfide nanoplate and carbon building blocks. A subsequent oxidation process produces SnO2 microspheres from hollow SnO2 nanoplate building blocks, which are formed by Kirkendall diffusion. The discharge capacity of the hierarchically structured SnO2 microspheres at a current density of 5 A·g?1 for the 600th cycle is 404 mA·h·g?1. The hierarchically structured SnO2 microspheres have reversible discharge capacities of 609 and 158 mA·h·g?1 at current densities of 0.5 and 30 A·g?1, respectively. The ultrafine nanosheets contain empty voids that allow excellent lithium-ion storage performance, even at high current densities. 相似文献
149.
We describe a new approach to the index reconstruction of three-dimensional optical systems with rotational symmetry, which is based on sampling ray paths that lie in the sagittal plane. Since the observed rays are distorted by the optical system itself, they cannot be used directly for index reconstruction. We present an iterative procedure to compute the true ray paths and then to find the index distribution. The utility of the method is verified on the model problem. 相似文献
150.
S.C.J. Kingsley G. Lawes A. Golov K. Matsumoto J.V. Porto E.N. Smith N. Mulders M.H.W. Chan J.M. Parpia 《Journal of Low Temperature Physics》1998,113(3-4):357-361
We have used a torsional oscillator to measure the superfluid density and dissipation near the superfluid transition of
3
He in aerogel of 99.5% porosity. We used a new cell (constructed at Penn State) for which the aerogel was grown in the pores of a 100 m silver sinter. The cell was tested with
4
He and showed no signs of the second-sound resonances that have interfered with previous torsional oscillator measurements. The measurements with
3
He, presented here, were taken at pressures of 1.34 and 4.13 bars. We observed values of
s
/ in the T 0 limit of 0.05 and 0.14 respectively. Our measurements show an increase in the dissipation on warming through T
c
. This series of measurements is ongoing and temperature sweeps at various pressures are planned. 相似文献