全文获取类型
收费全文 | 3634篇 |
免费 | 126篇 |
国内免费 | 3篇 |
专业分类
化学 | 2407篇 |
晶体学 | 39篇 |
力学 | 74篇 |
数学 | 263篇 |
物理学 | 980篇 |
出版年
2023年 | 38篇 |
2022年 | 60篇 |
2021年 | 62篇 |
2020年 | 91篇 |
2019年 | 109篇 |
2018年 | 70篇 |
2017年 | 61篇 |
2016年 | 132篇 |
2015年 | 80篇 |
2014年 | 123篇 |
2013年 | 240篇 |
2012年 | 236篇 |
2011年 | 291篇 |
2010年 | 177篇 |
2009年 | 150篇 |
2008年 | 218篇 |
2007年 | 183篇 |
2006年 | 163篇 |
2005年 | 141篇 |
2004年 | 112篇 |
2003年 | 77篇 |
2002年 | 75篇 |
2001年 | 60篇 |
2000年 | 58篇 |
1999年 | 46篇 |
1998年 | 29篇 |
1997年 | 23篇 |
1996年 | 38篇 |
1995年 | 30篇 |
1994年 | 35篇 |
1993年 | 43篇 |
1992年 | 29篇 |
1991年 | 27篇 |
1989年 | 19篇 |
1988年 | 21篇 |
1987年 | 27篇 |
1986年 | 21篇 |
1985年 | 19篇 |
1984年 | 31篇 |
1983年 | 20篇 |
1982年 | 23篇 |
1981年 | 30篇 |
1980年 | 19篇 |
1979年 | 27篇 |
1978年 | 16篇 |
1977年 | 18篇 |
1976年 | 16篇 |
1975年 | 15篇 |
1973年 | 11篇 |
1957年 | 13篇 |
排序方式: 共有3763条查询结果,搜索用时 15 毫秒
921.
922.
923.
Ghosh SK Alargova RG Deguchi S Tsujii K 《The journal of physical chemistry. B》2006,110(51):25901-25907
Dispersion stability of colloids has been investigated in sub- and supercritical water by measuring the hydrodynamic diffusion coefficients of the particles by means of dynamic light scattering. It is interestingly found that coagulation of the colloids in sub- and supercritical water is a universal phenomenon irrespective of the material of the colloids. Highly charged colloids were found to be more stable in water against high temperature. Numerical analysis reveals that the stability of the colloids at elevated temperature and pressure is primarily governed by the temperature dependence of the dielectric constant of the medium. The effect of the temperature dependence of the ion product of water (pKw) was found to be very little. Surface charge density and Stern potential may change with respect to temperature due to the readjustment of the ion concentration in the diffuse layer through the enhanced ion product and reduced dielectric constant of water. These are the secondary causes of the particle coagulations in sub- and supercritical water. 相似文献
924.
Sardar PS Maity SS Ghosh S Chatterjee J Maiti TK Dasgupta S 《The journal of physical chemistry. B》2006,110(42):21349-21356
Human placental ribonuclease inhibitor (hRI) containing six tryptophan (Trp) residues located at positions 19, 261, 263, 318, 375, and 438 and its complex with RNase A have been studied using steady-state and time-resolved fluorescence (298 K) as well as low-temperature phosphorescence (77 K). Two Trp residues in wild-type hRI and also in the protein-protein complex with RNase A are resolved optically. The accessible surface area values of Trp residues in the wild-type hRI and its complex and consideration of inter-Trp energy transfer in the wild-type hRI reveal that one of the Trp residues is Trp19, which is located in a hydrophobic buried region. The other Trp residue is tentatively assigned as Trp375 based on experimental results on wild-type hRI and its complex. This residue in the wild-type hRI is more or less solvent exposed. Both the Trp residues are perturbed slightly on complex formation. Trp19 moves slightly toward a more hydrophobic region, and the environment of Trp375 becomes less solvent exposed. The complex formation also results in a more heterogeneous environment for both the optically resolved Trp residues. 相似文献
925.
In this paper, we consider the Fischer–Marsden conjecture within the frame-work of K-contact manifolds and \((\kappa ,\mu )\)-contact manifolds. First, we prove that a complete K-contact metric satisfying \(\mathcal {L}^{*}_g(\lambda )=0\) is Einstein and is isometric to a unit sphere \(S^{2n+1}\). Next, we prove that if a non-Sasakian \((\kappa ,\mu )\)-contact metric satisfies \(\mathcal {L}^{*}_g(\lambda )=0\), then \( M^{3} \) is flat, and for \(n > 1\), \(M^{2n+1}\) is locally isometric to the product of a Euclidean space \(E^{n+1}\) and a sphere \(S^n(4)\) of constant curvature \(+\,4\). 相似文献
926.
927.
Randip K. Das Souvik Bhattacharyya M. DuttaGupta B. B. Ghosh 《Experimental Thermal and Fluid Science》1999,19(4):243-222
The fuel economy potential of lean-burn gasoline engines can be utilized without any adverse effect on the environment, only if a suitable catalytic system for converting NOx in an oxidizing atmosphere is available. Selective catalytic reduction of NOx over metal-exchanged zeolite can be one of the solutions for reducing NOx in automobile exhaust containing excess oxygen. Iron-exchanged X-zeolite catalyst (Fe–X) has been developed and tested in the exhaust of an actual SI engine over a wide range of air–fuel ratio, space velocity (SV) and catalyst temperature. Maximum conversion efficiencies of 55.8% and 57.4% were recorded for NOx and CO, respectively. The catalyst also maintains its high performance through a wide range of temperatures. A mathematical model has been developed as well for predicting the performance of the catalytic converter containing Fe–X catalyst and the numerical solutions are presented. The predicted results agree well with the experimental results and are within the experimental uncertainty limits. The absolute average deviations are found to be within 6% and 5% of the predicted conversion efficiencies for NOx and CO, respectively. 相似文献
928.
The sharp depletion of attenuation of 22.235 GHz signal before the onset of Nor’wester over Kolkata, India is observed and
possible explanation of such type of variation is presented. It is concluded that this may be taken as one possible method
of forecasting severe thunderstorm associated with Nor’wester. Physical explanations based on the formation and dissipation
mechanisms of thunderstorm are also presented. 相似文献
929.
930.