全文获取类型
收费全文 | 264616篇 |
免费 | 889篇 |
国内免费 | 284篇 |
专业分类
化学 | 116217篇 |
晶体学 | 3432篇 |
力学 | 15981篇 |
综合类 | 7篇 |
数学 | 43881篇 |
物理学 | 86271篇 |
出版年
2019年 | 2290篇 |
2018年 | 10871篇 |
2017年 | 11629篇 |
2016年 | 7726篇 |
2015年 | 2549篇 |
2014年 | 3693篇 |
2013年 | 7142篇 |
2012年 | 9361篇 |
2011年 | 17665篇 |
2010年 | 11663篇 |
2009年 | 12017篇 |
2008年 | 15703篇 |
2007年 | 18938篇 |
2006年 | 5794篇 |
2005年 | 10449篇 |
2004年 | 7571篇 |
2003年 | 7445篇 |
2002年 | 5839篇 |
2001年 | 5140篇 |
2000年 | 4006篇 |
1999年 | 2865篇 |
1998年 | 2645篇 |
1997年 | 2474篇 |
1996年 | 2441篇 |
1995年 | 2156篇 |
1994年 | 2100篇 |
1993年 | 2122篇 |
1992年 | 2146篇 |
1991年 | 2457篇 |
1990年 | 2387篇 |
1989年 | 2432篇 |
1988年 | 2330篇 |
1987年 | 2367篇 |
1986年 | 2177篇 |
1985年 | 2724篇 |
1984年 | 2742篇 |
1983年 | 2387篇 |
1982年 | 2441篇 |
1981年 | 2347篇 |
1980年 | 2148篇 |
1979年 | 2476篇 |
1978年 | 2649篇 |
1977年 | 2658篇 |
1976年 | 2778篇 |
1975年 | 2573篇 |
1974年 | 2504篇 |
1973年 | 2719篇 |
1972年 | 2176篇 |
1971年 | 1991篇 |
1970年 | 1875篇 |
排序方式: 共有10000条查询结果,搜索用时 412 毫秒
981.
982.
983.
984.
G.J. Zalmai Qing-hong Zhang 《应用数学学报(英文版)》2007,23(2):217-234
In this paper,we discuss a large number of sets of global parametric sufficient optimality condi-tions under various gcneralized (η,ρ)-invexity assumptions for a semi-infinite minmax fractional programmingproblem. 相似文献
985.
A. V. Kopylov I. V. Orekhov V. V. Petukhov A. E. Solomatin 《Physics of Atomic Nuclei》2006,69(11):1829-1832
Experiments sensitive to pp neutrinos from the Sun are very promising for precise measurement of the mixing angle ϑ
12. A νe
− scattering experiment (XMASS) and/or a charged-current experiment (indium detector) can measure the flux of electron pp neutrinos. One can find the total flux of pp neutrinos from a luminosity constraint after the contributions of 7Be and CNO neutrinos to the total luminosity of the Sun are measured. A radiochemical experiment utilizing a lithium target
has high sensitivity to the CNO neutrinos; thus, it has a good promise for precise measurement of the mixing angle and for
a test of the current theory of evolution of the stars.
The text was submitted by the authors in English. 相似文献
986.
V. S. Bilanych I. I. Makauz T. D. Mel’nichenko I. M. Rizak V. M. Rizak 《Physics of the Solid State》2006,48(11):2060-2064
The internal friction in Ge x As40 ? x S60 glasses is investigated in the temperature range 100 K-T g at infralow frequencies (10?3?10?1 Hz). It is shown that the concentration dependence of the internal friction of these materials changes as a result of the transformation of the dominant kinetic unit in dissipative processes of the relaxation and nonrelaxation types. It is established tha the change in the mechanism of internal friction in the Ge x As40 ? x S60 glasses leads to a jump in the activation energy of the α relaxation and to a local minimum in the frequency factor τ0. 相似文献
987.
I. Angeli 《Acta Physica Hungarica A》2006,25(1):47-56
The smooth N and Z dependence of nuclear rms charge radii is interpereted by a two-liquid drop model with ?p+?n=?0=const. Proton and neutron radii R p and R n are given in closed form. In addition to rms charge radii, the model yields the nucleon number dependence of the skin thickness, s, e.g. ds=0.00124×dA for Sn isotopes, in agreement with experimental results and theoretical calculations. A strong correlation between the two global parameters of the model — including s stthe skin thickness of the stable isotope — is established. If s stis taken from experiment, the other parameter is also fixed; this parameter (m) characterizes the restoring force responsible for the skin thickness. Its value m=2.2 suggests that — in addition to the number of nucleons in the skin — the skin thickness also influences the distribution of “surplus” nucleons between volume and skin. 相似文献
988.
V. V. Tarasov N. E. Kruchinina S. A. Shilin N. I. Shchedrova 《Russian Journal of Applied Chemistry》2006,79(6):945-948
A prototype reactor for heterogeneous hydrodynamic coagulation of emulsions was developed and tested. The efficiency of coagulation of water emulsions of some organic liquids was studied in relation to process conditions. 相似文献
989.
Electron beam processing of poly(ethylene terephthalate) (PET) films is found to promote significant changes in the melting heat, intrinsic viscosity and polymer film-liquid (water, isooctane and toluene) boundary surface tension. These properties are featured with several maximums depending on the absorbed dose and correlating with the modification of PET surface functionality. Studies using adsorption of acid-base indicators and IR-spectroscopy revealed that the increase of PET surface hydrophilicity is determined by the oxidation of methylene and methyne groups. Electron beam treatment of PET films on the surface of N-vinylpyrrolidone aqueous solution provided graft copolymerization with this comonomer at optimum process parameters (energy 700 keV, current 1 mA, absorbed dose 50 kGy). 相似文献
990.
A nonclassical problem is considered for the transport equation with coefficients depending on the energy of radiation. The task is to find the discontinuity surfaces for the coefficients of the equation from measurements of the radiation flux leaving the medium. For this tomography problem, an optimization problem is stated and numerically analyzed. The latter consists in determining the radiation energy that ensures the best reconstruction of the unknown medium. A simplified optimization problem is solved analytically. 相似文献