全文获取类型
收费全文 | 1630篇 |
免费 | 60篇 |
国内免费 | 128篇 |
专业分类
化学 | 1204篇 |
晶体学 | 32篇 |
力学 | 67篇 |
综合类 | 7篇 |
数学 | 260篇 |
物理学 | 248篇 |
出版年
2024年 | 3篇 |
2023年 | 6篇 |
2022年 | 24篇 |
2021年 | 28篇 |
2020年 | 35篇 |
2019年 | 24篇 |
2018年 | 28篇 |
2017年 | 17篇 |
2016年 | 27篇 |
2015年 | 48篇 |
2014年 | 42篇 |
2013年 | 98篇 |
2012年 | 84篇 |
2011年 | 100篇 |
2010年 | 107篇 |
2009年 | 119篇 |
2008年 | 89篇 |
2007年 | 94篇 |
2006年 | 85篇 |
2005年 | 59篇 |
2004年 | 70篇 |
2003年 | 48篇 |
2002年 | 94篇 |
2001年 | 51篇 |
2000年 | 45篇 |
1999年 | 30篇 |
1998年 | 48篇 |
1997年 | 38篇 |
1996年 | 30篇 |
1995年 | 42篇 |
1994年 | 32篇 |
1993年 | 24篇 |
1992年 | 15篇 |
1991年 | 18篇 |
1990年 | 25篇 |
1989年 | 14篇 |
1988年 | 10篇 |
1987年 | 11篇 |
1986年 | 11篇 |
1985年 | 9篇 |
1984年 | 9篇 |
1983年 | 4篇 |
1982年 | 4篇 |
1980年 | 2篇 |
1979年 | 5篇 |
1978年 | 2篇 |
1976年 | 2篇 |
1974年 | 4篇 |
1973年 | 1篇 |
1966年 | 1篇 |
排序方式: 共有1818条查询结果,搜索用时 0 毫秒
1.
V.B. Nalbandyan 《Journal of Physics and Chemistry of Solids》2004,65(6):1201
The irreproducibility of electrical properties of Na0.88Li0.12NbO3 solid solution on thermal cycling reported by M.A.L. Nobre and S. Lanfredi is explained by gradual decomposition of the supersaturated solid solution below ca. 800 °C. 相似文献
2.
3.
We use the PCP-SAFT equation of state, which is of the Van der Waals type and has a sound physical basis, to predict mixture properties, such as vapor–liquid and liquid–liquid equilibria, as well as excess enthalpies. We use molecular properties, such as dipole moment, quadrupole moment, polarizability and dispersion interaction coefficients, that have been determined quantum mechanically in Part I of this publication and adjust the remaining three pure compound parameters to pure compound data. We finally present a new combination rule for the dispersion energy parameter ? that is based on the quantum mechanically determined data. The predictions based on quantum mechanically determined pure compound properties along with the new combination rule show an improved performance compared to the original PCP-SAFT combination rule. 相似文献
4.
Nash Equilibria,Variational Inequalities,and Dynamical Systems 总被引:2,自引:0,他引:2
Cavazzuti E. Pappalardo M. Passacantando M. 《Journal of Optimization Theory and Applications》2002,114(3):491-506
In this paper, we introduce some relationships between Nash equilibria, variational equilibria, and dynamical equilibria for noncooperative games. 相似文献
5.
Preparation of Papers 总被引:8,自引:0,他引:8
We motivate the study of a vector variational inequality by a practical flow equilibrium problem on a network, namely a generalization of the well-known Wardrop equilibrium principle. Both weak and strong forms of the vector variational inequality are discussed and their relationships to a vector optimization problem are established under various convexity assumptions. 相似文献
6.
正已醇-邻、间、对二甲苯二元系固液相平衡 总被引:1,自引:0,他引:1
Melting temperatures have been measured and the solid-liquid phase diagrams constructed for 1-hexanol+o-xylene, 1-hexanol+m-xylene and 1-hexanol+p-xylene. They are simple eutectic systems. Excess mole Gibbs free energies were calculated at 298.15K, showing larger positive deviations from ideal-solution behavior. The largest values of GmE are 711、 650 and 800 J•mol-1 for {o-C6H4(CH3)2+C6H13OH}、 {m-C6H4(CH3)2 + C6H13OH} and {p-C6H4(CH3)2+C6H13OH} respectively. 相似文献
7.
The solubility of glycine,
-alanine,
-valine,
-leucine, and
-isoleucine in water was measured at 298.15 K and pressures up to 400 MPa. The standard deviation of the logarithm of the solubility is 0.001–0.003, equal to or better than the accuracy of atmospheric pressure measurement in the literature (0.001–0.05). A variety of solubility phenomena were observed. The solubility of glycine decreased with increasing pressure, whereas that of
-alanine increased. The
-valine and
-isoleucine have a solubility maximum at around 100 MPa, and
-leucine seems to exhibit a solid-phase phase transition at around 200 MPa. Pressure coefficient of the solubilities at 0.10 MPa is compared with that thermodynamically estimated in reference to aqueous density measurements of glycine and
-alanine at 298.15 K and 0.10 MPa, supporting a reliability of our high-pressure measurements. 相似文献
8.
Solubility behaviors of binary mixtures of CFCl3 (R-11), CFCl2-CF2Cl (R-113), CHCl3 (R-20), CDCl3 (R-20-d), CHCl2–CF3 (R-123) with room-temperature ionic liquid [bmim][PF6] (1-butyl-3-methylimidazolium hexafluorophosphate) have been investigated using the volumetric and cloud-point methods, since all the systems show liquid–liquid equilibria (LLE). Large immiscibility (LLE) gaps of the perhalogenated compounds (R-11 and R-113) in the ionic liquid have been drastically reduced by the addition of only one hydrogen (or deuterium) in these compounds. The R-123 + [bmim][PF6] binary system belongs to the Type-V fluid behavior. Noticeably large negative values (−2 to −8 cm3 mol−1) of the excess molar volume in the ionic liquid-rich side solution have been observed for all the present systems. Experimental LLE data have been well correlated by the use of the NRTL (non-random two liquid) activity coefficient model. 相似文献
9.
10.
A preparative one-step method for the synthesis of 1,1,1,5,5,5-hexafluoro-4-trifluoromethylpentane-2,3-dione dihydrazone from perfluoro-4-methylpent-2-ene and hydrazine hydrate has been developed. Oxidation of this dihydrazone with bromine in water gives 3-diazo-1,1,1,5,5,5-hexafluoro-4-trifluoromethylpentane-2-one. The same product is obtained from 3-hydrazono-1,1,1,5,5,5-hexafluoro-4-trifluoromethylpentane-2-one under similar conditions.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2039–2041, November, 1994.This work was supported by the Russian Foundation for Basic Research (the project code 94-03-08548). 相似文献