全文获取类型
收费全文 | 171篇 |
免费 | 26篇 |
国内免费 | 21篇 |
专业分类
化学 | 93篇 |
晶体学 | 2篇 |
力学 | 2篇 |
数学 | 38篇 |
物理学 | 83篇 |
出版年
2022年 | 3篇 |
2021年 | 10篇 |
2020年 | 3篇 |
2019年 | 5篇 |
2018年 | 3篇 |
2017年 | 4篇 |
2016年 | 11篇 |
2015年 | 4篇 |
2014年 | 7篇 |
2013年 | 29篇 |
2012年 | 7篇 |
2011年 | 9篇 |
2010年 | 6篇 |
2009年 | 9篇 |
2008年 | 10篇 |
2007年 | 4篇 |
2006年 | 4篇 |
2005年 | 2篇 |
2004年 | 7篇 |
2003年 | 9篇 |
2002年 | 14篇 |
2001年 | 8篇 |
2000年 | 13篇 |
1999年 | 2篇 |
1998年 | 1篇 |
1997年 | 3篇 |
1994年 | 2篇 |
1993年 | 3篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1989年 | 6篇 |
1988年 | 3篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1983年 | 1篇 |
1982年 | 3篇 |
1981年 | 1篇 |
1976年 | 1篇 |
1948年 | 3篇 |
排序方式: 共有218条查询结果,搜索用时 488 毫秒
31.
Farid Rachidi Mutale-joan Chanda Redouane Benhima Mernissi Najib EL Abderahime Aasfar Laila Sbabou Arroussi Hicham EL 《Applied biochemistry and biotechnology》2019,188(1):225-240
Applied Biochemistry and Biotechnology - Microalgae are photosynthetic microorganisms that produce several bioactive molecules that have received considerable attention in scientific and industrial... 相似文献
32.
We used Monte Carlo method to generate the configurations of disassembly of hot nucleus Au* based on the Atomic Mass Table and the conservation of mass and charge number.The resulted charge distribution of fragments was then used to calculate the conditional moments.The logarithm correlation between second and third moments of experimental charge distribution is very well reproduced by theory.It seems that no connection to the critical phenomenon of concerned system exists. 相似文献
33.
In this paper a simplified method for the calculation of average Coulomb energy in statistical model of the disassembly processes of hot nuclei is proposed.The effect of freeze-out volume is studied based on the assumption of Gaussion-like distribution.It is indecated that the centre and dispersion of Gaussion-like distribution somewhat reflect the location and the renge of liquid-gas coexistence phase. 相似文献
34.
THE EVIDENCE OF DECONFINEMENT PHASE TRANSITION OF SU(2) LATTICE GAUGE MODEL BY MONTE CARLO METHOD
下载免费PDF全文
![点击此处可从《中国物理C(英文版)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
In this paper,we have calculated the SU(2) lattice gauge by the Monte Carlo method.For the finite temperature problem 83×4 lattice is used and for the zero temperature problem 84 lattice.From the calculations of the energy density,heat capacity and entropy density,the results indicate that there is a deconfinement phase transition when T/ΛL=40—50. 相似文献
35.
The distributions of dynamic variables in the deep inelastic scattering (DIS) of heavy-ions are studied by a direct simulation technique based on the single-nucleon-transfer-mechanism. The relative motion of the two collision partners is described by a Lagrange equation, and the transition probability of a single nucleon during the interaction time is calculated by the statisti-cal spectroscopy method.The occurrence of the transition event and the corresponding change of the dynamic variables are both treated randomly according to the transition probability. The calculated results for the reaction of 40Ar+58Ni(EL=280MeV) are compared with experimental data. 相似文献
36.
Exploration for Degradation of Λ Polarization Produced in Relativistic Nucleus Nucleus Collisions
下载免费PDF全文
![点击此处可从《中国物理C(英文版)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
YE YunXiu CHEN Zhi RUAN TuNan SHEN Ji LV HaiJiang DONG WeiJiang SA BenHao TAI An 《中国物理C(英文版)》2000,24(2):125-130
The degradation of Λ transverse polarization produced in S+Pb central collisions at energy 200 GeV per nucleon has been studied in detail. The S+Pb central collision events have been generated using Monte-Carlo generator——LUCIAE at 200 GeV per nucleon. The various factors degrading Λ transverse polarization have been analysed quantitatively. The ratios of Λ′s produced from rescattering, secondary production and decays of Σ, Ξ hyperons to the total measurable Λ′s in experiment have been investigeted and the degradation effect of these Λ on the total polarization has been determined. The simulation and calculation show that above three factors decrease the Λ transverse polarization strongly, however, can not eliminate the polarization completely when the Λ′s are assumed to be produced from hadronic gas in the final state. To explan the experimental data of vanished Λ polarization, it probably needs to consider new mechanisms of Λ production, including a weak effect of QGP formation. 相似文献
37.
38.
The transport of carbamazepine, ciprofloxacin and sulfamethoxazole in the different pores of activated carbon in an aqueous solution is a dynamic process that is entirely dependent on the intrinsic parameters of these molecules and of the adsorbent. The macroscopic processes that take place are analyzed by interfacial diffusion and reaction models. Modeling of the experimental kinetic curves obtained following batch treatment of each solute at 2 µg/L in tap water showed (i) that the transport and sorption rates were controlled by external diffusion and intraparticle diffusion and (ii) that the effective diffusion coefficient for each solute, with the surface and pore diffusion coefficients, were linked by a linear relationship. A statistical analysis of the experimental data established correlations between the diffusional parameters and some geometrical parameters of these three molecules. Given the major discontinuities observed in the adsorption kinetics, the modeling of the experimental data required the use of traditional kinetic models, as well as a new kinetic model composed of the pseudo first or second order model and a sigmoidal expression. The predictions of this model were excellent. The solubility of each molecule below 60 °C was formulated by an empirical expression. 相似文献
39.
We report on the accelerated ageing of cellulose based insulating paper by means of pulsed UV laser irradiation (λ = 248 nm)
under various experimental conditions including paper composition, background gas (He, N2 and air) and moisture content of the paper. The temperature reached by the paper samples during their laser irradiation was
monitored by means of real-time IR imaging. It is shown that the equilibrium temperature (T
eq) reached by the paper increases from ~30 to ~270 °C when the laser energy density was raised from 15 to 550 mJ cm−2. The laser irradiated samples were systematically characterized by means of scanning electron microscopy (SEM) observations
and degree of polymerization (DPv) measurements. Interestingly, it is found that, for a given moisture content, the degradation level of the cellulose is mainly
triggered by the T
eq value reached during the laser irradiation. Moreover, their moisture content was found to influence significantly the number
of laser produced bond scissions (it doubles when the moisture content is increased from 0.5 to 6%); the paper degradation
is apparently not affected by the presence of oxygen as the background gas. These results suggest that the laser induced cellulose
degradation occurs through a direct photolysis (i.e. direct breakage of C–C, C–O and C–H bonds), leading to radicals formation,
which, in turn, are believed to induce the acid hydrolysis degradation mechanism, the latter being moisture dependent. The
activation energy (E
a) of each gaseous species collected after the laser degradation was estimated. Their E
a values were found to be in good agreement with the one associated to the laser depolymerisation of cellulose (i.e. ~56 kJ mol−1), suggesting thereby a direct correlation between the cellulose degradation and the formation of the detected gaseous species.
Finally, the pulsed laser irradiation can be seen as an attractive tool to identify primarily generated molecules, on a very
short time scale, that can be used as relevant chemical markers for the monitoring of the ageing of transformers materials
with cellulose. 相似文献
40.
基于尖晶石晶体结构信息,本文采用热力学三亚晶格模型,将材料热力学计算和第一性原理计算相结合,研究了Zn_xMn_(1-x) Fe_2O_4和Ni_xMn_(1-x)Fe_2O_4立方相中的Zn~(2+)、Ni~(2+)、Mn~(2+)以及Fe~(3+)在8a和16d亚晶格上的占位有序化行为。结果表明:在锰铁氧体中,室温下Mn~(2+)完全占据在8a亚晶格上,Fe~(3+)完全占据在16d亚晶格上,属于正尖晶石结构;随着热处理温度升高,在1 273 K达到热处理平衡时的占位构型为(Fe~(3+)0.09Mn~(2+)0.91)[Fe~(3+)1.91Mn~(2+)0.09]O_4,在热处理温度升至1 473 K时,达到热处理平衡时的占位构型为(Fe~(3+)0.11Mn~(2+)0.89)[Fe~(3+)1.89Mn~(2+)0.11]O_4,均与实验结果符合较好。在锌铁氧体中,室温下Zn~(2+)完全占据在8a亚晶格上,Fe~(3+)完全占据在16d亚晶格上,属于正尖晶石结构;在热处理温度较高时,Zn~(2+)和Fe~(3+)发生部分置换,符合实验结果。在镍铁氧体中,半数的Fe~(3+)在室温下占据在8a亚晶格上,Ni~(2+)与剩下另一半的Fe~(3+)共同占据在16d亚晶格上,仅在热处理温度较高的时候发生微弱变化,亦与已有的实验结果吻合。在此基础上,本文进一步通过热力学模型研究了立方相尖晶石结构的Zn_xMn_(1-x)Fe_2O_4、Ni_xMn_(1-x)Fe_2O_4复合体系中阳离子占位行为与热处理温度对占位的影响规律。 相似文献