全文获取类型
收费全文 | 261篇 |
免费 | 38篇 |
国内免费 | 57篇 |
专业分类
化学 | 301篇 |
晶体学 | 1篇 |
力学 | 11篇 |
综合类 | 6篇 |
数学 | 1篇 |
物理学 | 36篇 |
出版年
2024年 | 1篇 |
2023年 | 14篇 |
2022年 | 23篇 |
2021年 | 21篇 |
2020年 | 17篇 |
2019年 | 16篇 |
2018年 | 17篇 |
2017年 | 16篇 |
2016年 | 20篇 |
2015年 | 22篇 |
2014年 | 16篇 |
2013年 | 24篇 |
2012年 | 33篇 |
2011年 | 23篇 |
2010年 | 7篇 |
2009年 | 20篇 |
2008年 | 13篇 |
2007年 | 13篇 |
2006年 | 19篇 |
2005年 | 8篇 |
2004年 | 9篇 |
2003年 | 3篇 |
1957年 | 1篇 |
排序方式: 共有356条查询结果,搜索用时 312 毫秒
21.
Microfluidic systems promise solutions for high throughput and highly specific analysis for biology, medicine and chemistry while consuming only tiny amounts of reactants and space. On these lab‐on‐a‐chip platforms often multiple physical effects such as electrokinetic, acoustic or capillary phenomena from various disciplines are exploited to gain the optimal functionality. The fluidics on these small length scales differ significantly from our experience of the macroscopic world. In this Review we survey some of the approaches and techniques to handle minute amounts of fluid volumes in microfluidic systems with special focus on surface acoustic wave driven fluidics, a technique developed in our laboratory. Here, we outline the basics of this technique and demonstrate, for example, how acoustic mixing and fluid actuation is realized. Furthermore we discuss the interplay of different physical effects in microfluidic systems and illustrate their usefulness for several applications. 相似文献
22.
This paper demonstrates the application of the topology optimization method as a general and systematic approach for microfluidic mixer design. The mixing process is modeled as convection dominated transport in low Reynolds number incompressible flow. The mixer performance is maximized by altering the layout of flow/non‐flow regions subject to a constraint on the pressure drop between inlet and outlet. For a square cross‐sectioned pipe the mixing is increased by 70% compared with a straight pipe at the cost of a 2.5 fold increase in pressure drop. Another example where only the bottom profile of the channel is a design domain results in intricate herring bone patterns that confirm findings from the literature. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
23.
In this paper, an experimental study and modeling by artificial neural networks were carried out to predict the generated microdroplet dimensionless size in a microfluidic system in order to formulate a water-in-oil emulsion. The various parameters that affect the size of microdroplets (flow rates, viscosities, surface tensions of both the two phases and the diameter of the microchannel) are studied and further grouped into dimensionless numbers; we used these numbers as input to the neural network and the dimensionless length as output. The better neural network architecture has 10 neurons in the hidden layer with a mean square error of 1.4 10?6 and a determination’s coefficient near 1 value. The relative importance of inputs on the size of the microdroplets has been determined using the Garson algorithm and the results are in good agreement with other works. 相似文献
24.
We report a self‐propelled Janus silica micromotor as a motion‐based analytical method for achieving fast target separation of polyelectrolyte microcapsules, enriching different charged organics with low molecular weights in water. The self‐propelled Janus silica micromotor catalytically decomposes a hydrogen peroxide fuel and moves along the direction of the catalyst face at a speed of 126.3 μm s?1. Biotin‐functionalized Janus micromotors can specifically capture and rapidly transport streptavidin‐modified polyelectrolyte multilayer capsules, which could effectively enrich and separate different charged organics in water. The interior of the polyelectrolyte multilayer microcapsules were filled with a strong charged polyelectrolyte, and thus a Donnan equilibrium is favorable between the inner solution within the capsules and the bulk solution to entrap oppositely charged organics in water. The integration of these self‐propelled Janus silica micromotors and polyelectrolyte multilayer capsules into a lab‐on‐chip device that enables the separation and analysis of charged organics could be attractive for a diverse range of applications. 相似文献
25.
Josef Janča 《International Journal of Polymer Analysis and Characterization》2015,20(8):671-680
Micro-thermal field-flow fractionation was used to characterize the particle size distribution of nanometer-sized diamond nanoparticles. Although the experimental conditions were chosen to perform high-speed separation, and, consequently, the resolution achieved experimentally was not very high, the application of the original correction method for the zone spreading allowed for obtaining of very good calculated particle size distribution or, explicitly, a true polydispersity index of the diamond nanoparticle sample. The future use of several samples of diamond nanoparticles of different average sizes and different surface chemistries should allow deeper insight into the effect of these particulate characteristics on the retention in micro-thermal field-flow fractionation. 相似文献
26.
27.
28.
The shape of the steady-state three-dimensional flow velocity profile established in carrier liquid flowing inside the rectangular cross-sectional channel for field-flow fractionation should be taken into account to optimize the separation. The central parts of this profile in the planes parallel to the main channel walls are flat with almost identical flow velocities which drop down to zero at the side walls. The separated species transported by the flow in the close-to-side walls regions move with lower average velocities compared to the species transported in the central part of the channel and are undesirably broadened. The hydrodynamic splitting of the carrier liquid at the entry of the channel where the sample is injected only into the central part of the channel eliminates the excessive zone broadening. The aspect ratio of the breadth to the thickness of the channel ratio can thus be reduced. The effect of various aspect ratios on the shape of the flow velocity profile is calculated and the results are used to optimize the aspect ratio of microfluidic channels. The experiments carried out by microthermal field-flow fractionation confirmed that the aspect ratio cannot be reduced to a value of 1, proposed by other authors. 相似文献
29.
蛋白质组体系的高度复杂性需要更高分辨率的多维分离技术。近年兴起的液滴技术在微纳尺度样品操控方面具有微体积、低扩散、无返混等独特优势,有望为多维分离平台的接口提供解决方案。通过采用不同结构的液滴微流控芯片可以实现“液滴生成”与“油相排除”功能,进行样品由连续流-非连续流-连续流的高效转移,将不同的分离模式进行二维耦联。本研究利用液滴作为接口技术耦联高效液相色谱与毛细管电泳构建二维分离系统,以蛋白质降解的复杂多肽混合物为样品,考察了液滴接口二维分离平台的可行性和有效性,并获得3000以上的峰容量,初步展示了该接口技术在多维分离分析领域的应用潜力。 相似文献
30.