全文获取类型
收费全文 | 524258篇 |
免费 | 7455篇 |
国内免费 | 1785篇 |
专业分类
化学 | 280345篇 |
晶体学 | 5966篇 |
力学 | 22395篇 |
综合类 | 9篇 |
数学 | 67175篇 |
物理学 | 157608篇 |
出版年
2020年 | 4128篇 |
2019年 | 4340篇 |
2018年 | 5357篇 |
2017年 | 5098篇 |
2016年 | 8807篇 |
2015年 | 6460篇 |
2014年 | 8995篇 |
2013年 | 24556篇 |
2012年 | 19023篇 |
2011年 | 22789篇 |
2010年 | 15054篇 |
2009年 | 14714篇 |
2008年 | 20821篇 |
2007年 | 20934篇 |
2006年 | 19948篇 |
2005年 | 18217篇 |
2004年 | 16445篇 |
2003年 | 14483篇 |
2002年 | 14194篇 |
2001年 | 15424篇 |
2000年 | 12001篇 |
1999年 | 9565篇 |
1998年 | 7835篇 |
1997年 | 7524篇 |
1996年 | 7011篇 |
1995年 | 6717篇 |
1994年 | 6569篇 |
1993年 | 6460篇 |
1992年 | 6947篇 |
1991年 | 6857篇 |
1990年 | 6414篇 |
1989年 | 6186篇 |
1988年 | 6499篇 |
1987年 | 6088篇 |
1986年 | 5842篇 |
1985年 | 8316篇 |
1984年 | 8479篇 |
1983年 | 6930篇 |
1982年 | 7360篇 |
1981年 | 7346篇 |
1980年 | 7005篇 |
1979年 | 7278篇 |
1978年 | 7329篇 |
1977年 | 7305篇 |
1976年 | 7308篇 |
1975年 | 6941篇 |
1974年 | 6883篇 |
1973年 | 7053篇 |
1972年 | 4491篇 |
1971年 | 3522篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
992.
V. A. Popov S. I. Lopatin L. Sh. Tsemekhman L. A. Pavlinova S. P. Kormilitsyn V. V. Barsegyan 《Russian Journal of Applied Chemistry》2003,76(10):1564-1567
Evaporation of chromium ore and concentrates was studied using high-temperature differential mass-spectrometry. The data obtained, concerning the component vapor pressures in evaporation of complex oxide systems in the range 1700-2100 K, can be used to calculate the evaporation loss in melting and to assess the possibility of utilization of the sublimates formed. 相似文献
993.
994.
995.
The ρ-T curves in our single phase HgBa2Ca2Cu3O8+δ superconductor were measured as a function of temperature and magnetic field, ρ=ρ0exp(−Ueff/κBT). It can be transformed to another form d(lnρ)/d(1/T)=−Ueff+TdUeff/dT, then this becomes a plot of the activation energy Ueff as a function of temperature. Our data plotted in these ways show a clear crossover from high-temperature two-dimensional vortex-liquid to a critical region associated with the low-temperature three-dimensional vortex-glass phase transition. The critical exponents v(z−1)=3.9±1.9 in this system are little different with previous measurements in BSCCO and YBCO systems. 相似文献
996.
B. Szafran P. S
p J. Adamowski S. Bednarek 《Physica E: Low-dimensional Systems and Nanostructures》2003,18(4):523-529
We present a theoretical study of the charging spectra in natural and artificial atoms. We apply a model electrostatic potential created by a homogenously charged sphere. This model potential allows for a continuous passage from the Coulomb potential of the nucleus to parabolic confinement potential of quantum dots. We consider electron systems with N=1,…,10 electrons with the use of the Hartree–Fock method. We discuss the qualitative similarities and differences between the chemical potential spectrum of electron systems bound to nucleus and confined in quantum dots. 相似文献
997.
J. T. Hoeft M. Polcik D. I. Sayago M. Kittel R. Terborg R. L. Toomes J. Robinson D. P. Woodruff M. Pascal G. Nisbet C. L. A. Lamont 《Surface science》2003,540(2-3):441-456
The local adsorption geometry of CO adsorbed in different states on Ni(1 0 0) and on Ni(1 0 0) precovered with atomic hydrogen has been determined by C 1s (and O 1s) scanned-energy mode photoelectron diffraction, using the photoelectron binding energy changes to characterise the different states. The results confirm previous spectroscopic assignments of local atop and bridge sites both with and without coadsorbed hydrogen. The measured Ni–C bondlengths for the Ni(1 0 0)/CO states show an increase of 0.16 ± 0.04 Å in going from atop to bridge sites, while comparison with similar results for Ni(1 1 1)/CO for threefold coordinated adsorption sites show a further lengthening of the bond by 0.05 ± 0.04 Å. These changes in the Ni–CO chemisorption bondlength with bond order (for approximately constant adsorption energy) are consistent with the standard Pauling rules. However, comparison of CO adsorbed in the atop geometry with and without coadsorbed hydrogen shows that the coadsorption increases the Ni–C bondlength by only 0.06 ± 0.04 Å, despite the decrease in adsorption energy of a factor of 2 or more. This result is also reproduced by density functional theory slab calculations. The results of both the experiments and the density functional theory calculations show that CO adsorption onto the Ni(1 0 0)/H surface is accompanied by significant structural modification; the low desorption energy may then be attributed to the energy cost of this restructuring rather than weak local bonding. 相似文献
998.
999.
We propose means for computing the Fourier expansions of periodic
functions appearing in higher moments of the sum-of-digits
function and in the solutions of some divide-and-conquer
recurrences. The expansions are shown to be absolutely
convergent. We also give a new approach to efficiently compute
numerically the coefficients involved to high precision. 相似文献
1000.
The results of experimental investigation into the mechanical properties of blends of low-density polyethylene (LDPE) with chlorinated polyethylene (CPE) in tension are presented. The specimens of pure LDPE, CPE, and nine types of LDPE/CPE blends, with different content of components at 10 wt.% intervals, were examined. Data on the influence of blend composition on the tensile stress-strain diagram, elastic modulus, yield stress, breaking stress, and ultimate elongation are obtained. The results of investigations of creep are also reported. It is found that the creep compliance (the total current compliance minus the elastic compliance) obeys the power law of creep.__________Translated from Mekhanika Kompozitnykh Materialov, Vol. 41, No. 3, pp. 391–404, May–June, 2005. 相似文献