全文获取类型
收费全文 | 1252篇 |
免费 | 52篇 |
专业分类
化学 | 1105篇 |
晶体学 | 11篇 |
力学 | 6篇 |
数学 | 64篇 |
物理学 | 118篇 |
出版年
2024年 | 2篇 |
2023年 | 19篇 |
2022年 | 116篇 |
2021年 | 108篇 |
2020年 | 35篇 |
2019年 | 31篇 |
2018年 | 37篇 |
2017年 | 35篇 |
2016年 | 78篇 |
2015年 | 44篇 |
2014年 | 56篇 |
2013年 | 92篇 |
2012年 | 80篇 |
2011年 | 92篇 |
2010年 | 64篇 |
2009年 | 48篇 |
2008年 | 71篇 |
2007年 | 69篇 |
2006年 | 41篇 |
2005年 | 47篇 |
2004年 | 36篇 |
2003年 | 26篇 |
2002年 | 24篇 |
2001年 | 8篇 |
2000年 | 5篇 |
1999年 | 2篇 |
1998年 | 2篇 |
1997年 | 6篇 |
1996年 | 3篇 |
1995年 | 2篇 |
1994年 | 5篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1988年 | 4篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1982年 | 1篇 |
1981年 | 3篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
排序方式: 共有1304条查询结果,搜索用时 46 毫秒
91.
Micha Sowa Katarzyna
lepokura Ewa Matczak‐Jon 《Acta Crystallographica. Section C, Structural Chemistry》2012,68(7):o262-o265
Cocrystallization of baicalein with nicotinamide yields a 1:1 cocrystal [systematic name: pyridine‐3‐carboxamide–5,6,7‐trihydroxy‐2‐phenyl‐4H‐chromen‐4‐one (1/1)], C6H6N2O·C15H10O5. The asymmetric unit contains one baicalein and one nicotinamide molecule, both in neutral forms. Molecules in the cocrystal form column motifs stabilized by an array of intermolecular hydrogen bonds. 相似文献
92.
93.
94.
Despite being size-extensive, the "second-generation" 1-matrix functionals for the electron-electron repulsion energy V(ee) yield vanishing correlation energy for the homogeneous electron gas. This failure is directly related to the idempotency condition imposed upon an auxiliary matrix that enters the expression for V(ee). In particular, the recently proposed Kollmar-Hess functional is not volume-extensive and thus is incapable of properly describing any delocalized system at its thermodynamic limit. 相似文献
95.
Urszula Koss Mariusz ?ukaszewski Katarzyna Hubkowska Andrzej Czerwi��ski 《Journal of Solid State Electrochemistry》2011,15(11-12):2477-2487
Hydrogen electrosorption into Pd-rich (>80?at.% Pd in the bulk) Pd?CRh alloys has been studied in acidic solutions (0.5?M H2SO4) using cyclic voltammetry and chronoamperometry. The influence of temperature (in the range between 283 and 328?K), electrode potential and alloy bulk composition on hydrogen electrosorption properties of Pd?CRh alloys is presented. It has been found that the additive of Rh to Pd?CRh alloys increases the maximum hydrogen solubility (for Rh bulk content below 10?at.%), decreases the potential of absorbed hydrogen oxidation peak and decreases the potential of the ???????? phase transition. Increasing temperature decreases the potential of absorbed hydrogen oxidation peak, the maximum hydrogen solubility, and the potential of the ???????? phase transition. The amounts of electrosorbed hydrogen for ??- and ??-phase boundaries, i.e., ??max and ??min, have been determined from the integration of the initial parts of current?Ctime responses in hydrogen absorption and desorption processes. The H/M ratio corresponding to ??max increases with increasing Rh content, while for ??min a maximum of H/M ratio is observed for the alloys containing ca. 95% Rh. 相似文献
96.
The lattices generated by the families of quasicontinuous and τ-quasicontinuous functions are described. 相似文献
97.
Vikram Kestens Guy Auclair Katarzyna Drozdzewska Andrea Held Gert Roebben Thomas Linsinger 《Journal of Thermal Analysis and Calorimetry》2010,99(1):245-261
In this study, the use of differential scanning calorimetry (DSC) is demonstrated as a powerful technique that can provide
accurate thermodynamic property values of environmental contaminants such as polycyclic aromatic hydrocarbons (PAHs). In total,
47 high purity PAH certified reference materials were selected and analysed by DSC. Their onset melting temperature, enthalpy
of fusion and eutectic purity were calculated from the obtained melting endotherms. In addition, the entropy of fusion, which
was calculated from the onset melting temperature and enthalpy of fusion, is presented. All measurements were evaluated in
a metrologically rigorous manner, including measurement uncertainties. 相似文献
98.
99.
Gas-induced geodynamic phenomena can occur during underground mining operations if the porous structure of the rock is filled with gas at high pressure. In such cases, the original compact rock structure disintegrates into grains of small dimensions, which are then transported along the mine working space. Such geodynamic events, particularly outbursts of gas and rock, pose a danger both to the life of miners and to the functioning of the mine infrastructure. These incidents are rare in copper ore mining, but they have recently begun to occur, and have not yet been fully investigated. To ensure the safety of mining operations, it is necessary to determine parameters of the rock–gas system for which the energy of the gas will be smaller than the work required to disintegrate and transport the rock. Such a comparison is referred to as an energy balance and serves as a starting point for all engineering analyses. During mining operations, the equilibrium of the rock–gas system is disturbed, and the rapid destruction of the rock is initiated together with sudden decompression of the gas contained in its porous structure. The disintegrated rock is then transported along the mine working space in a stream of released gas. Estimation of the energy of the gas requires investigation of the type of thermodynamic transformation involved in the process. In this case, adiabatic transformation would mean that the gas, cooled in the course of decompression, remains at a temperature significantly lower than that of the surrounding rocks throughout the process. However, if we assume that the transformation is isothermal, then the cooled gas will heat up to the original temperature of the rock in a very short time (<1 s). Because the quantity of energy in the case of isothermal transformation is almost three times as high as in the adiabatic case, obtaining the correct energy balance for gas-induced geodynamic phenomena requires detailed analysis of this question. For this purpose, a unique experimental study was carried out to determine the time required for heat exchange in conditions of very rapid flows of gas around rock grains of different sizes. Numerical simulations reproducing the experiments were also designed. The results of the experiment and the simulation were in good agreement, indicating a very fast rate of heat exchange. Taking account of the parameters of the experiment, the thermodynamic transformation may be considered to be close to isothermal. 相似文献
100.
Enhancement of the Efficacy of Photodynamic Inactivation of Candida albicans with the Use of Biogenic Gold Nanoparticles 下载免费PDF全文
Irena Maliszewska Barbara Lisiak Katarzyna Popko Katarzyna Matczyszyn 《Photochemistry and photobiology》2017,93(4):1081-1090
This study reports on successful photodynamic inactivation of planktonic and biofilm cells of Candida albicans using Rose Bengal (RB) in combination with biogenic gold nanoparticles synthesized by the cell‐free filtrate of Penicillium funiculosum BL1 strain. Monodispersed colloidal gold nanoparticles coated with proteins were characterized by a number of techniques including SEM–EDS, TEM, UV–Vis absorption and fluorescence spectroscopy, as well as Fourier transform infrared spectroscopy to be 24 ± 3 nm spheres. A Xe lamp (output power of 20mW, delivering intensity of 53 mW cm?2) was used as a light source to study the effects of RB alone, the gold nanoparticles alone and the RB‐gold nanoparticle mixture on the viability of C. albicans cells. The most effective reduction in the number of planktonic cells was found after 30 min of Xe lamp light irradiation (95.4 J cm?2) and was 4.89 log10 that is 99.99% kill for the mixture of RB with gold nanoparticles compared with 2.19 log10 or 99.37% for RB alone. The biofilm cells were more resistant to photodynamic inactivation, and the highest effective reduction in the number of cells was found after 30 min of irradiation in the presence of the RB–gold nanoparticles mixture and was 1.53 log10, that is 97.04% kill compared with 0.6 log10 or 74.73% for RB. The probable mechanism of enhancement of RB‐mediated photodynamic fungicidal efficacy against C. albicans in the presence of biogenic gold nanoparticles is discussed leading to the conclusion that this process may have a multifaceted character. 相似文献