全文获取类型
收费全文 | 3881篇 |
免费 | 394篇 |
国内免费 | 138篇 |
专业分类
电工技术 | 223篇 |
综合类 | 211篇 |
化学工业 | 774篇 |
金属工艺 | 188篇 |
机械仪表 | 167篇 |
建筑科学 | 261篇 |
矿业工程 | 127篇 |
能源动力 | 123篇 |
轻工业 | 235篇 |
水利工程 | 51篇 |
石油天然气 | 105篇 |
武器工业 | 9篇 |
无线电 | 549篇 |
一般工业技术 | 556篇 |
冶金工业 | 273篇 |
原子能技术 | 52篇 |
自动化技术 | 509篇 |
出版年
2024年 | 16篇 |
2023年 | 48篇 |
2022年 | 103篇 |
2021年 | 120篇 |
2020年 | 83篇 |
2019年 | 69篇 |
2018年 | 95篇 |
2017年 | 105篇 |
2016年 | 122篇 |
2015年 | 158篇 |
2014年 | 191篇 |
2013年 | 257篇 |
2012年 | 240篇 |
2011年 | 296篇 |
2010年 | 245篇 |
2009年 | 211篇 |
2008年 | 249篇 |
2007年 | 191篇 |
2006年 | 224篇 |
2005年 | 151篇 |
2004年 | 113篇 |
2003年 | 126篇 |
2002年 | 149篇 |
2001年 | 119篇 |
2000年 | 84篇 |
1999年 | 88篇 |
1998年 | 80篇 |
1997年 | 81篇 |
1996年 | 58篇 |
1995年 | 54篇 |
1994年 | 38篇 |
1993年 | 32篇 |
1992年 | 29篇 |
1991年 | 35篇 |
1990年 | 12篇 |
1989年 | 13篇 |
1988年 | 14篇 |
1987年 | 6篇 |
1986年 | 10篇 |
1984年 | 10篇 |
1983年 | 12篇 |
1982年 | 9篇 |
1981年 | 8篇 |
1980年 | 6篇 |
1979年 | 7篇 |
1976年 | 12篇 |
1975年 | 5篇 |
1970年 | 4篇 |
1965年 | 3篇 |
1964年 | 3篇 |
排序方式: 共有4413条查询结果,搜索用时 15 毫秒
71.
以SiO和蔗糖为原料,SiO经高温歧化反应处理后,通过机械球磨、喷雾干燥、高温热解工艺制备出具有优异电化学性能的锂离子电池SiO/C负极材料。经XRD、FTIR、XPS、SEM、TEM结构分析表明,歧化反应处理的片状SiO包含非晶态SiO和纳米晶相Si、SiO_2,蔗糖热解形成的无定形碳包覆在细片状SiO的表面,组成球形SiO/C颗粒。电化学测试结果表明,预歧化处理的SiO/C复合材料的首次放电容量为1 314.6mAh/g,首次库伦效率达到71%;100周循环后的放电容量为851.2mAh/g,容量保持率达到78.5%,循环稳定性远高于未经歧化处理的SiO/C复合材料。电化学性能的提高归因于SiO预歧化反应及热解碳包覆。 相似文献
72.
YongTai Zhang Kai Zhang Zhe Li HongYu Zhang Teng Guo YanYan Li JiHui Zhao NianPing Feng 《IET nanobiotechnology / IET》2018,12(8):1037
The main objective of this work was to investigate the uptake channels of skin cells through which coumarin 6, transported by deoxycholate‐mediated liposomes (DOC‐LS), was internalised; this was also compared against the action of conventional LS. Coumarin 6‐loaded DOC‐LS and LS were characterised for size distribution, zeta potential, and shape, and analysed in vitro in human epidermal immortal keratinocyte (HaCaT) (epidermal) and human embryonic skin fibroblast (CCC‐ESF‐1) (dermal) cell lines. Various endocytosis inhibitors were incubated with cells treated with the nanocarriers. Flow cytometry results indicated that HaCaT and CCC‐ESF‐1 cells internalise the tested preparations through pinocytotic vesicles, macropinocytosis, clathrin‐mediated endocytic pathways, and via lysosomes, which consume a considerable amount of energy. The endocytosis pathways of DOC‐LS and LS showed no difference. This study provides a basis for the application of LS being combined with a microneedle system for efficient intracellular drug delivery, targeting cutaneous histocyte disorders.Inspec keywords: drugs, nanoparticles, lipid bilayers, nanomedicine, biomedical materials, electrokinetic effects, biomembrane transport, drug delivery systems, skin, organic compoundsOther keywords: dermal delivery, CCC‐ESF‐1 cells, skin cells, deoxycholate‐mediated liposomes, coumarin 6‐loaded DOC‐LS, endocytosis inhibitors, clathrin‐mediated endocytic pathways, endocytosis pathways, HaCaT cell lines, size distribution, zeta potential, nanocarriers, flow cytometry, pinocytotic vesicles, macropinocytosis, microneedle system, efficient intracellular drug delivery, targeting cutaneous histocyte disorders 相似文献
73.
本文介绍了公交优先策略的概念和分类,阐述了绿灯延长、绿灯提前、相位倒转、相位插入、公交通行专用相位等主动优先控制策略的基本原理,并对其进行了适应性和优缺点分析。 相似文献
74.
Meng T Entezari A Smith B Möller T Weiskopf D Kirkpatrick AE 《IEEE transactions on visualization and computer graphics》2011,17(10):1420-1432
The Body-Centered Cubic (BCC) and Face-Centered Cubic (FCC) lattices have been analytically shown to be more efficient sampling lattices than the traditional Cartesian Cubic (CC) lattice, but there has been no estimate of their visual comparability. Two perceptual studies (each with N = 12 participants) compared the visual quality of images rendered from BCC and FCC lattices to images rendered from the CC lattice. Images were generated from two signals: the commonly used Marschner-Lobb synthetic function and a computed tomography scan of a fish tail. Observers found that BCC and FCC could produce images of comparable visual quality to CC, using 30-35 percent fewer samples. For the images used in our studies, the L(2) error metric shows high correlation with the judgement of human observers. Using the L(2) metric as a proxy, the results of the experiments appear to extend across a wide range of images and parameter choices. 相似文献
75.
Alpana Agarwal C.F. Tai J.N. Chung 《Computer Methods in Applied Mechanics and Engineering》2010,199(17-20):1080-1090
An accurate finite-volume based numerical method for the simulation of an isothermal two-phase flow, consisting of a rising deformable bubble translating in a quiescent, unbounded liquid, is presented. This direct simulation method is built on a sharp interface concept and developed on an Eulerian, Cartesian fixed-grid with a cut-cell scheme and marker points to track the moving interface. The unsteady Navier–Stokes equations in both liquid and gas phases are solved separately. The mass continuity and momentum flux conditions are explicitly matched at the true surface phase boundary to determine the evolving interface shape and movement of the bubble. The highlights of this method are that it utilizes a combined Eulerian–Lagrangian approach, and is capable of treating the interface as a sharp discontinuity. A fixed underlying grid is used to represent the control volume. The interface, however, is denoted by a separate set of marker particles which move along with the interface. A quadratic curve fitting algorithm with marker points is used to yield smooth and accurate information of the interface curvatures. This numerical scheme can handle a wide range of density and viscosity ratios. The bubble is assumed to be spherical and at rest initially, but deforms as it rises through the liquid pool due to buoyancy. Additionally, the flow is assumed to be axisymmetric and incompressible. The bubble deformation and dynamic motion are characterized by the Reynolds number, the Weber number, the density ratio and the viscosity ratio. The effects of these parameters on the translational bubble dynamics and shape are given and the physical mechanisms are explained and discussed. Results for the shape, velocity profile and various forces acting on the bubble are presented here as a function of time until the bubble reaches terminal velocity. The range of Reynolds numbers investigated is 1 < Re < 100, and that of Weber number is 1 < We < 10. 相似文献
76.
77.
78.
79.
Juyong Zhang Chunlin Wu Jianfei Cai Jianmin Zheng Xue‐cheng Tai 《Computer Graphics Forum》2010,29(2):517-526
This paper considers the problem of interactively finding the cutting contour to extract components from a given mesh. Some existing methods support cuts of arbitrary shape but require careful and tedious input from the user. Others need little user input however they are sensitive to user input and need a postprocessing step to smooth the generated jaggy cutting contours. The popular geometric snake can be used to optimize the cutting contour, but it cannot deal with the topology change. In this paper, we propose a geodesic curvature flow based framework to overcome all these problems. Since in many cases the meaningful cutting contour on a 3D mesh is locally shortest in the sense of some weighted curve length, the geodesic curvature flow is an ideal tool for our problem. It evolves the cutting contour to the nearby local minimum. We should mention that the previous numerical scheme, discretized geodesic curvature flow (dGCF) is too slow and has not been applied to mesh segmentation. With a careful observation to dGCF, we devise here a fast computation scheme called fast geodesic curvature flow (FGCF), which only needs to solve a smaller and easier problem. The initial cutting contour is generated by a variant of random walks algorithm, which is very fast and gives reasonable cutting result with little user input. Experiment results on the benchmark mesh segmentation data set show that our proposed framework is robust to user input and capable of producing good results reflecting geometric features and human shape perception. 相似文献
80.
We present a new intuitive UI, which we call cross‐boundary brushes, for interactive mesh decomposition. The user roughly draws one or more strokes across a desired cut and our system automatically returns a best cut running through all the strokes. By the different natures of part components (i.e., semantic parts) and patch components (i.e., flatter surface patches) in general models, we design two corresponding brushes: part‐brush and patch‐brush. These two types of brushes share a common user interface, enabling easy switch between them. The part‐brush executes a cut along an isoline of a harmonic field driven by the user‐specified strokes. We show that the inherent smoothness of the harmonic field together with a carefully designed isoline selection scheme lead to segmentation results that are insensitive to noise, pose, tessellation and variation in user's strokes. Our patch‐brush uses a novel facet‐based surface metric that alleviates sensitivity to noise and fine details common in region‐growing algorithms. Extensive experimental results demonstrate that our cutting tools can produce user‐desired segmentations for a wide variety of models even with single strokes. We also show that our tools outperform the state‐of‐art interactive segmentation tools in terms of ease of use and segmentation quality. 相似文献