全文获取类型
收费全文 | 473篇 |
免费 | 10篇 |
国内免费 | 4篇 |
专业分类
化学 | 247篇 |
晶体学 | 9篇 |
力学 | 20篇 |
数学 | 29篇 |
物理学 | 182篇 |
出版年
2022年 | 4篇 |
2021年 | 7篇 |
2018年 | 4篇 |
2017年 | 4篇 |
2016年 | 7篇 |
2015年 | 6篇 |
2014年 | 10篇 |
2013年 | 12篇 |
2012年 | 11篇 |
2011年 | 17篇 |
2010年 | 11篇 |
2009年 | 9篇 |
2008年 | 13篇 |
2007年 | 24篇 |
2006年 | 25篇 |
2005年 | 15篇 |
2004年 | 11篇 |
2003年 | 9篇 |
2002年 | 15篇 |
2001年 | 10篇 |
2000年 | 22篇 |
1999年 | 4篇 |
1998年 | 3篇 |
1996年 | 4篇 |
1995年 | 10篇 |
1994年 | 9篇 |
1993年 | 20篇 |
1992年 | 19篇 |
1991年 | 7篇 |
1990年 | 14篇 |
1989年 | 10篇 |
1988年 | 10篇 |
1987年 | 6篇 |
1986年 | 4篇 |
1985年 | 6篇 |
1984年 | 12篇 |
1983年 | 10篇 |
1982年 | 9篇 |
1980年 | 8篇 |
1979年 | 9篇 |
1977年 | 6篇 |
1976年 | 8篇 |
1975年 | 6篇 |
1968年 | 4篇 |
1934年 | 3篇 |
1927年 | 2篇 |
1917年 | 4篇 |
1890年 | 2篇 |
1889年 | 2篇 |
1885年 | 2篇 |
排序方式: 共有487条查询结果,搜索用时 15 毫秒
51.
52.
53.
54.
A liquid sloshing absorber consists of a container, partially filled with liquid. The absorber is attached to the structure to be controlled, and relies on the structure’s motion to excite the liquid. Consequently, a sloshing wave is produced at the liquid free surface within the absorber, possessing energy dissipative qualities. The behaviour of liquid sloshing absorbers has been well documented, although their use in structural control applications has attracted considerably less attention. 相似文献
55.
In this paper,we study the surface instability of a cylindrical pore in the absence of stress. This instability is called the Rayleigh-Plateau instabilty. We consider the model developed by Spencer et ... 相似文献
56.
Haskins RW Maier RS Ebeling RM Marsh CP Majure DL Bednar AJ Welch CR Barker BC Wu DT 《The Journal of chemical physics》2007,127(7):074708
We performed tight-binding molecular dynamics on single-walled carbon nanotubes with and without a variety of defects to study their effect on the nanotube modulus and failure through bond rupture. For a pristine (5,5) nanotube, Young's modulus was calculated to be approximately 1.1 TPa, and brittle rupture occurred at a strain of 17% under quasistatic loading. The predicted modulus is consistent with values from experimentally derived thermal vibration and pull test measurements. The defects studied consist of moving or removing one or two carbon atoms, and correspond to a 1.4% defect density. The occurrence of a Stone-Wales defect does not significantly affect Young's modulus, but failure occurs at 15% strain. The occurrence of a pair of separated vacancy defects lowers Young's modulus by approximately 160 GPa and the critical or rupture strain to 13%. These defects apparently act independently, since one of these defects alone was independently determined to lower Young's modulus by approximately 90 GPa, also with a critical strain of 13%. When the pair of vacancy defects adjacent, however, Young's modulus is lowered by only approximately 100 GPa, but with a lower critical strain of 11%. In all cases, there is noticeable strain softening, for instance, leading to an approximately 250 GPa drop in the apparent secant modulus at 10% strain. When a chiral (10,5) nanotube with a vacancy defect was subjected to tensile strain, failure occurred through a continuous spiral-tearing mechanism that maintained a high level of stress (2.5 GPa) even as the nanotube unraveled. Since the statistical likelihood of defects occurring near each other increases with nanotube length, these studies may have important implications for interpreting the experimental distribution of moduli and critical strains. 相似文献
57.
Abstract. Angiotensin is readily inactivated by ultraviolet light presumably due to the photosensitivity of its tyrosyl and phenylalanyl residues. Alkalinity promotes and acidity delays the biological decomposition. Under conditions of oxygen exclusion (i.e. under N2 or H2 ) the rate of decomposition is further depressed and when irradiation is carried out under hydrogen a biologically active product is formed. This altered angiotensin, judging from its chromatographic migration and dialysis rate, represents a polymerized form of angiotensin. Under identical irradiation conditions, angiotensin was coupled with C14 labelled pheny-lalanine which indicates that this residue might be the photoreactive species. The production of altered forms of angiotensin by ultraviolet irradiation was discussed with respect to possible utility in anti-metabolite, antigen or tracer work. 相似文献
58.
Charles W. Marsh 《Fresenius' Journal of Analytical Chemistry》1890,29(1):687-688
Ohne Zusammenfassung 相似文献
59.
J. E. Marsh 《Fresenius' Journal of Analytical Chemistry》1890,29(1):680
Ohne Zusammenfassung 相似文献
60.
James O. Marsh Thomas W. Crowe Jeffrey Hesler 《International Journal of Infrared and Millimeter Waves》1990,11(9):1113-1131
This paper considers a novel doping profile for Schottky barrier mixer diodes called the Mott barrier. The structure consists of a metal-semiconductor junction in which the semiconductor's epitaxial layer is very lightly doped and thin enough so that it remains depleted even under substantial forward bias. It has been proposed that Mott barrier diodes will generate less noise and have lower series resistance-junction capacitance products than standard Schottky diodes, thus increasing the sensitivity and cut-off frequency of heterodyne receivers. In this paper, the band structure and electron transport properties of the Mott diode are evaluated. This analysis shows that the Mott diode actually will have a large series resistance-junction capacitance product and excessive hot electron noise, making it a poor candidate for high-frequency applications. Experimental results are presented which substantiate these conclusions. 相似文献