全文获取类型
收费全文 | 415篇 |
免费 | 11篇 |
国内免费 | 2篇 |
专业分类
化学 | 256篇 |
力学 | 5篇 |
数学 | 35篇 |
物理学 | 132篇 |
出版年
2021年 | 4篇 |
2020年 | 5篇 |
2019年 | 5篇 |
2018年 | 6篇 |
2016年 | 6篇 |
2015年 | 4篇 |
2014年 | 12篇 |
2013年 | 16篇 |
2012年 | 25篇 |
2011年 | 13篇 |
2010年 | 5篇 |
2009年 | 11篇 |
2008年 | 13篇 |
2007年 | 17篇 |
2006年 | 24篇 |
2005年 | 20篇 |
2004年 | 23篇 |
2003年 | 16篇 |
2002年 | 14篇 |
2001年 | 14篇 |
2000年 | 16篇 |
1999年 | 2篇 |
1998年 | 7篇 |
1997年 | 3篇 |
1996年 | 9篇 |
1995年 | 2篇 |
1994年 | 10篇 |
1993年 | 3篇 |
1992年 | 7篇 |
1991年 | 3篇 |
1990年 | 10篇 |
1989年 | 5篇 |
1988年 | 8篇 |
1987年 | 4篇 |
1986年 | 7篇 |
1985年 | 8篇 |
1984年 | 4篇 |
1983年 | 4篇 |
1982年 | 5篇 |
1981年 | 4篇 |
1980年 | 4篇 |
1979年 | 9篇 |
1978年 | 7篇 |
1977年 | 8篇 |
1974年 | 3篇 |
1973年 | 3篇 |
1972年 | 3篇 |
1971年 | 2篇 |
1930年 | 2篇 |
1927年 | 3篇 |
排序方式: 共有428条查询结果,搜索用时 15 毫秒
51.
Mathematics and Financial Economics - We derive the optimal portfolio for an investor with increasing relative risk aversion in a complete continuous-time securities market. The IRRA assumption... 相似文献
52.
H.S. Margolis J. Asada T.V. Back D.J. Bieber F.J. Currell E.G. Myers N. Nakamura S. Ohtani P.K. Oxley M. Sakurai J.D. Silver H. Watanabe 《Hyperfine Interactions》1998,112(1-4):139-142
The presence of the σ-phase in Fe-Cr alloys (eg. Stainless steel) is important in industrial applications and from an academic
point of view. The presence of the σ-phase in these alloys drastically affects their mechanical properties and their resistance
to various corrosive media. In the present investigation Fe-Cr alloys containing different amounts of Mo were prepared and
the transformation to the σ-phase was carried out by isothermally annealing the samples for various periods in an argon atmosphere.
It will be shown that the presence of Mo has a dramatic accelerating effect on the rate of the σ-phase formation in these
alloys.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
53.
54.
The rotating-sector method has been applied to the photoinitiated radical-chain decomposition of formamide at 300°C to measure the rate constant for the bimolecular disappearance of NH2 radicals. The decomposition is propagated by the reactions (1) (2) Conditions were chosen so that reaction (1) was rate controlling and NH2 the terminating radical. A flow system was employed with C2F6 as a carrier gas at a pressure of 300 Tort, and the chain reaction was initiated by the photolysis of either formamide or NH3. A value of 4.7(±2.0) × 1010 (M ·sec)?1 was estimated for the termination reaction (3) and a value of 8.4 × 106 (M ·sec)?1 for reaction (1) in the same system, both at 300°C. 相似文献
55.
56.
A method is described for the measurement of relative rate constants for abstraction of hydrogen from ethylene at temperatures in the region of 750 K. The method is based on the effect of the addition of small quantities of propane and isobutane on the rates of formation of products in the thermal chain reactions of ethylene. On the assumption that methane and ethane are formed by the following reactions, (1) measurements of the ratio of the rates of formation of methane and ethane in the presence and absence of the additive gave the following results: Values for k2 and k3 obtained from these ratios are compared with previous measurements. 相似文献
57.
58.
Fission fragment angular distributions from sequential fission induced in heavy-ion reactions will depend on the angular momentum exchange occuring in such reactions in considerable detail. Theoretical expressions for the angular distributions of fission products from totally and partly polarized nuclei are presented. They are compared with recent measurements and discussed in relation to the deep inelastic reaction mechanism. 相似文献
59.
An equation is derived on semi-theoretical grounds which expresses the solid-vapour surface free energy as a function of the liquid surface tension and the solid-liquid interfacial free energy. A means of calculating reliable values for the solid-liquid energy is presented, which then allows an accurate estimate of solid surface energy at the melting temperature, Tm, to be made for the large number of elements for which dependable liquid surface tension data exist. A method of estimating surface entropy is presented, and has been used to calculate the energies typical of “average”, high-index surfaces at temperatures ranging from 0 K to Tm. It is felt that this paper describes the most accurate method presently available for the calculation of the surface energy of solids in the absence of direct experimental measurement. 相似文献
60.
Neudecker I Kläui M Perzlmaier K Backes D Heyderman LJ Vaz CA Bland JA Rüdiger U Back CH 《Physical review letters》2006,96(5):057207
The spatially resolved eigenmode spectrum of micrometer-sized Co ring elements has been determined by means of combined vector network analyzer ferromagnetic resonance and time resolved magneto-optic Kerr effect measurements. Up to 5 resonant eigenmodes were observed in the frequency range from 45 MHz to 20 GHz as a function of an external magnetic bias field. A well-defined mode structure was found for the two equilibrium states (vortex and onion) which correspond to distinctive spatial modes. The effect of dynamic inter-ring coupling on the modes in the remanent states was evinced. The experimental results are found to be in good agreement with those of micromagnetic simulations. Our results demonstrate that, in analogy to the well-defined static equilibrium magnetic states of ring elements, the eigenmode spectra of this high symmetry geometry consist of a well-defined and simple mode structure. 相似文献