全文获取类型
收费全文 | 223篇 |
免费 | 7篇 |
国内免费 | 1篇 |
专业分类
化学 | 158篇 |
晶体学 | 2篇 |
力学 | 1篇 |
数学 | 49篇 |
物理学 | 21篇 |
出版年
2023年 | 2篇 |
2022年 | 6篇 |
2021年 | 1篇 |
2020年 | 4篇 |
2019年 | 1篇 |
2018年 | 4篇 |
2017年 | 2篇 |
2016年 | 4篇 |
2015年 | 2篇 |
2014年 | 6篇 |
2013年 | 3篇 |
2012年 | 10篇 |
2011年 | 14篇 |
2010年 | 5篇 |
2009年 | 12篇 |
2008年 | 10篇 |
2007年 | 18篇 |
2006年 | 14篇 |
2005年 | 13篇 |
2004年 | 9篇 |
2003年 | 11篇 |
2002年 | 12篇 |
2001年 | 4篇 |
2000年 | 4篇 |
1999年 | 8篇 |
1998年 | 4篇 |
1997年 | 4篇 |
1996年 | 4篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1989年 | 4篇 |
1988年 | 1篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1978年 | 4篇 |
1977年 | 3篇 |
1976年 | 3篇 |
1975年 | 7篇 |
1974年 | 1篇 |
1973年 | 4篇 |
1972年 | 1篇 |
1968年 | 1篇 |
1911年 | 2篇 |
排序方式: 共有231条查询结果,搜索用时 15 毫秒
91.
Liu L. Loh N. H. Tay B. Y. Tor S. B. Yin H. Q. Qu X. H. 《Applied Physics A: Materials Science & Processing》2011,103(4):1145-1151
Micro powder injection molding (μPIM) has been developed as a potential technique for mass production of microcomponents in microsystems due to its shaping
complexity at low cost, in which sintering is a crucial step to dictate the final properties of the microcomponents. In this
paper, final-stage sintering behavior of 316L stainless steel microsize structures prepared by μPIM, φ100 μm and φ60 μm, respectively, was studied. The effect of size reduction in the regime of micrometers on the density of various microsize
structures was investigated. Sintering kinetics of the microsize structures of φ100 μm and φ60 μm were studied based on particle level sintering models. It is found that the microsize structures of φ60 μm had higher density than the microsize structures of φ100 μm given the same sintering condition. The results indicate that size reduction in the regime of micrometers facilitated
densification of microsize structures. The grain growth mechanism of microsize structures varied with size. Whereas the grain
growth of the microsize structures of φ100 μm is governed by surface-diffusion-controlled pore drag, the grain growth of the microsize structures of φ60 μm is controlled by boundary diffusion. During densification, the microsize structures, φ100 μm and φ60 μm, are both controlled by lattice diffusion. The corresponding activation energies are reported in the paper. 相似文献
92.
G. Fu S. B. Tor N. H. Loh D. E. Hardt 《Applied Physics A: Materials Science & Processing》2009,97(4):925-931
In this paper, the fabrication of an array of 316L stainless steel cylindrical micro-structures by hot-embossing is studied.
The effects of various embossing parameters on the filling of the micro-cavities of silicon mold insert and the demolding
of micro-structures are investigated. They include different silicon mold insert configurations, embossing pressure, embossing
temperature, embossing time and the thickness of embossing substrate on which the micro-structures stand. Two types of silicon
mold insert configurations are investigated. Hot-embossing study with the silicon mold insert attached on the upper mold plate
shows that it is not feasible to achieve complete filling. Incomplete filling occurs and increasing the embossing pressure
causes excessive thinning of the embossing substrate, so that micro-structures are torn off during demolding. Experiments
show that the configuration that the silicon mold insert is positioned flush with lower mold surface improves complete filling.
Using suitable embossing pressure and temperature, the larger substrate thickness and longer embossing time ensure the fabrication
of defect-free fully filled micro-structures. 相似文献
93.
94.
95.
96.
The Goethals code is a binary nonlinear code of length 2m+1 which has
codewords and minimum Hamming distance 8 for any odd
. Recently, Hammons et. al. showed that codes with the same weight distribution can be obtained via the Gray map from a linear code over Z
4of length 2m and Lee distance 8. The Gray map of the dual of the corresponding Z
4 code is a Delsarte-Goethals code. We construct codes over Z
4 such that their Gray maps lead to codes with the same weight distribution as the Goethals codes and the Delsarte-Goethals codes. 相似文献
97.
Amin Ibrahim Philip B. Oldham Terrance E. Conners Tor P. Schultz 《Microchemical Journal》1997,56(3):393-402
FT-Raman spectroscopy is used for the rapid measurement of wood pulp lignin. A total of 23 western softwood pulp samples with known kappa numbers (10–38) are used. Each sample is divided into three portions and scanned separately. The integrated area of the lignin band at approximately 1600 cm−1is ratioed against the integrated area of the cellulose bands in the 1200–1010 cm−1region and correlated to known kappa numbers. The measured ratios behave linearly with the kappa number (r= 0.99) and can be reproducibly determined with an error of approximately 2% or less. The data are presented and discussed in view of the potential for at-line analysis of lignin associated with chemical delignification of wood pulp. 相似文献
98.
The molecular structures of gaseous cyclopentene oxide, cyclohexene oxide and cycloheptene oxide are investigated by electron diffraction. The boat conformation of cyclopentene oxide is confirmed, while a half-chair conformer is determined for cyclohexene oxide. Cycloheptene oxide is found to exist in a 66(2):34(2) conformational mixture of two chair forms. 相似文献
99.
A family of simple pyrimidine analogues has been synthesized, and their photophysical properties have been investigated. The most responsive of the family was incorporated in DNA. This isosteric fluorescent DNA analogue monitors denaturation of a DNA duplex via fluorescence and positively detects the presence of abasic sites in DNA duplexes. 相似文献
100.