全文获取类型
收费全文 | 154篇 |
免费 | 6篇 |
国内免费 | 6篇 |
专业分类
综合类 | 3篇 |
化学工业 | 24篇 |
金属工艺 | 9篇 |
机械仪表 | 53篇 |
建筑科学 | 11篇 |
能源动力 | 1篇 |
轻工业 | 16篇 |
水利工程 | 3篇 |
石油天然气 | 5篇 |
无线电 | 21篇 |
一般工业技术 | 17篇 |
冶金工业 | 1篇 |
原子能技术 | 1篇 |
自动化技术 | 1篇 |
出版年
2023年 | 1篇 |
2021年 | 2篇 |
2019年 | 1篇 |
2018年 | 3篇 |
2017年 | 3篇 |
2016年 | 4篇 |
2015年 | 6篇 |
2014年 | 9篇 |
2013年 | 3篇 |
2012年 | 4篇 |
2011年 | 17篇 |
2010年 | 11篇 |
2009年 | 15篇 |
2008年 | 11篇 |
2007年 | 14篇 |
2006年 | 7篇 |
2005年 | 10篇 |
2004年 | 8篇 |
2003年 | 8篇 |
2002年 | 6篇 |
2001年 | 9篇 |
1999年 | 1篇 |
1998年 | 2篇 |
1997年 | 4篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 1篇 |
排序方式: 共有166条查询结果,搜索用时 15 毫秒
1.
2.
The ElectroScan environmental scanning electron microscope (ESEM) enables wet samples to be observed by eliminating air but allowing water vapour into the sample chamber. However, evaporation from, and condensation on, the sample may occur during the pumpdown sequence used to reach this state, which means that the sample may not be in its natural state when viewed if due care is not taken. In this paper, the pumping system of the ESEM is described mathematically and expressions are derived for the evaporation and condensation. This treatment is then used to calculate the optimum pumpdown sequence. The importance of using the optimized procedure is illustrated by micrographs of fat emulsions. 相似文献
3.
A simplified method for the preparation of particles from liquid suspensions has been developed. Particles are deposited directly on carbon planchets for rapid analysis by environmental scanning electron microscopy or by conventional scanning electron microscopy after an additional drying step. This is accomplished by filtering the liquid through thin carbon planchets. Three different grades of graphite were investigated for their suitability as the source material for these planchets. The high quality isomolded graphite is recommended for the filtration and direct observation of particles by electron microscopy. This technique is demonstrated for particles in hydraulic fluid and aquatic suspended particulate material from a natural water source. 相似文献
4.
Danilatos GD 《Journal of microscopy》2011,244(2):159-169
A recently introduced figure of merit for environmental and low vacuum scanning electron microscopes has now been computed in the full operational pressure range for one commercial instrument. The direct simulation Monte Carlo method has been used in lieu of experimental measurements. The theory of this figure of merit is further consolidated. It is shown that a thin pressure limiting aperture can indeed be used as an optimum reference system for all instruments employing differential pumping in the transfer of an electron beam from high vacuum to high pressure. The implications of the results obtained are discussed both in relation to existing commercial instruments and associated literature to pave the way for future progress in the field. 相似文献
5.
The combined application of electron microscopy (EM) is frequently used for the microstructural investigation of biological specimens and plays two important roles in the quantification and in gaining an improved understanding of biological phenomena by making use of the highest resolution capability provided by EM. The possibility of imaging wet specimens in their "native" states in the environmental scanning electron microscope (ESEM) at high resolution and large depth of focus in real time is discussed in this paper. It is demonstrated here that new features can be discovered by the elimination of even the least hazardous approaches in some preparation techniques, that destroy the samples. Since the analysis conditions may influence the morphology and the extreme surface sensitivity of living biological systems, the results obtained from the same cultured cell with two different ESEM modes (Lvac mode and wet mode) were compared. This offers new opportunities compared with ESEM-wet/Lvac-mode imaging, since wet-mode imaging involves a real contrast and gives an indication of the changes in cell morphology and structure required for cell viability. In this study, wet-mode imaging was optimized using the unique ability of cell quantities for microcharacterization in situ giving very fine features of topological effects. Accordingly, the progress is reported by comparing the results of these two modes, which demonstrate interesting application details. In general, the functional comparisons have revealed that the fresh unprocessed Saccharomyces cerevisiae cells (ESEM-wet mode) were essentially unaltered with improved and minimal specimen preparation timescales, and the optimal cell viability degree was visualized and also measured quantitatively while the cell size remained unchanged with continuous images. 相似文献
6.
7.
The aim of this study was analysis of a number of factors affecting the rheological properties of high performance inulin gels and spreads in comparison with commercial products. Inulin gels (20%, 25%, 30%), commercial and inulin model spread (20% canola oil, 20% inulin, 3% emulsifier) were analysed. Inulin particles in water environment absorbed water which caused an increase in viscosity of the inulin suspensions. Different temperatures of preparation, cooling rates and viscosity increase which appeared during the stirring of inulin suspensions did not significantly change the rheological parameters of the final gels in contrast to heating rates (p ? 0.05). In spite of rigid laboratory conditions high standard deviation for hardness and apparent viscosity showed how difficult the process of an inulin crystallization is to control. Rheological properties of inulin model spread exhibited thixotropic and shear thinning behaviour which made it similar to commercial spread. The applied structure destruction step in the manufacturing process should be applied to make inulin model spread comparable to commercial spreads. 相似文献
8.
Applications of environmental scanning electron microscopy (ESEM) in biomaterials field 总被引:1,自引:0,他引:1
Various tasks were undertaken in our laboratory where environmental scanning electron microscopy (ESEM) has been of particular interest within the biomaterials field. The possibility of observing wet samples, as well as the fact that sample preparation is minimal, has improved shorter time scales and lower costs in microscopy. Minimal preparation has also reduced the possibility of introducing artifacts. Examples like cell cultures used for pit resorption assays, calcium phosphate deposition processes, and dissolution of phosphate glasses used as biomaterials are presented. Finally, a servohydraulic testing machine designed for mechanical testing in situ in ESEM has allowed the study of shape memory alloys for orthodontic applications or the behavior of different adhesives used in odontology. 相似文献
9.
在环境扫描电镜(ESEM)中,采用高灵敏度的pA-表测试系统,测量法拉第杯,以及Cu-Zn合金、单晶Si、单晶Al2O3三种样品的样品电流(ISP)。ISP值反映出由电子流和离子流控制的ESEM样品室内的电荷环境。法拉第杯的ISP反映出入射电子和离子所控制的电荷环境;样品的ISP反映出入射电子、信号电子和离子所控制的电荷环境。由ISP值可确定ESEM在不同操作和环境条件下的离子化效率、离子化饱和程度,以及气体分子的散射作用。 相似文献
10.
Rosa Vera 《Corrosion Science》2008,50(4):1080-1098
This research work belongs to a series of studies simultaneously performed with two previous publications in this journal as Part I. Al and 6201 Al alloy and Part 2. Pure copper. The aim of the project was to have a comparative picture of the joint effect of marine and industrial atmospheric pollutants on the corrosion resistance of wire metals employed for high power electric transmission. This one is also based on the pure Cu behaviour, but limited to six marine-industrial atmospheres with extremely high SO2 contents. The interest in this study was triggered by unusual results considered appropriate to investigate. Weight loss after 4 and 11 months exposure was determined and morphology of the attack was analysed through SEM-ESEM-EDX. Polarisation of samples after exposure to all the test sites as compared to bare Cu clarified the effect of unusually high SO2 pollutant contents in these atmospheres on the high protectiveness of the corrosion products formed. 相似文献