全文获取类型
收费全文 | 7189篇 |
免费 | 700篇 |
国内免费 | 430篇 |
专业分类
化学 | 1879篇 |
晶体学 | 84篇 |
力学 | 1070篇 |
综合类 | 50篇 |
数学 | 923篇 |
物理学 | 3190篇 |
无线电 | 1123篇 |
出版年
2024年 | 18篇 |
2023年 | 69篇 |
2022年 | 146篇 |
2021年 | 199篇 |
2020年 | 201篇 |
2019年 | 148篇 |
2018年 | 173篇 |
2017年 | 197篇 |
2016年 | 156篇 |
2015年 | 196篇 |
2014年 | 254篇 |
2013年 | 578篇 |
2012年 | 400篇 |
2011年 | 479篇 |
2010年 | 339篇 |
2009年 | 403篇 |
2008年 | 377篇 |
2007年 | 418篇 |
2006年 | 413篇 |
2005年 | 352篇 |
2004年 | 350篇 |
2003年 | 326篇 |
2002年 | 283篇 |
2001年 | 214篇 |
2000年 | 220篇 |
1999年 | 148篇 |
1998年 | 195篇 |
1997年 | 172篇 |
1996年 | 133篇 |
1995年 | 103篇 |
1994年 | 92篇 |
1993年 | 79篇 |
1992年 | 88篇 |
1991年 | 41篇 |
1990年 | 54篇 |
1989年 | 32篇 |
1988年 | 36篇 |
1987年 | 25篇 |
1986年 | 30篇 |
1985年 | 36篇 |
1984年 | 23篇 |
1983年 | 9篇 |
1982年 | 29篇 |
1981年 | 13篇 |
1980年 | 12篇 |
1979年 | 11篇 |
1978年 | 14篇 |
1977年 | 6篇 |
1976年 | 9篇 |
1973年 | 7篇 |
排序方式: 共有8319条查询结果,搜索用时 15 毫秒
71.
Finite chains of a two-state random Potts spin model with periodic boundary conditions are studied within Glauber dynamics. The spin exchange is assumed random with frustration between ferro and antiferromagnetic values (±J). Time-dependent fluctuations are induced by periodic temperature oscillations. Master type differential equations for spin correlation functions are solved within linear response theory. The spectrum of relaxation times are calculated at different temperatures. The ±J Potts glass chains undergo a zero temperature phase transition. The barriers against inversion of the spin chain take only two values; 0 and 2|J|. The temperature behaviour of specific heat is characterized by rounded peaks. The frequency dependence displays two plateaus for the real part of specific heat and two corresponding peaks for the imaginary part. The dynamic specific heat is not affected by the longest relaxing mode like susceptibility. The time separation of the modes is demonstrated by the Cole-Cole plots. 相似文献
72.
潜热型热功能流体强化换热分析 总被引:4,自引:0,他引:4
本文建立了分析带有相变微胶囊的潜热型热功能流体的流动和换热过程数理模型,应用有限差分法和移动热源法进行联合求解。计算结果表明,相变微胶囊的加入:较好地提高了流体的换热性能。获得了相变颗粒大小和体积分数对强化换热影响等结果。计算结果对该类流体的设计和应用提供了理论依据。 相似文献
73.
Taking both the heterogeneous catalytic processes, including the surface formation of particles with excited internal degrees of freedom, and the processes of multicomponent diffusion and heat transfer in the MESOX apparatus fully into account makes it possible to obtain a recombination coefficient and an accommodation coefficient of the oxygen-atoms-on-quartz recombination energy which are in good agreement with the experimental data. The heterogeneous catalysis model constructed can be used effectively for predicting the heat fluxes to the surface of reentry vehicles on their entry into the Earth’s atmosphere. 相似文献
74.
75.
76.
77.
78.
赵建民 《微电子学与计算机》1996,13(1):20-21,29
本文从锅炉运行技术指标台帐微机管理的实际出发,提出了热量计算中主蒸汽流量修正系数C和给水焓值Z两项参数回归的计算公式,提高了热量计算数值精度。 相似文献
79.
J.-L. Garden 《Thermochimica Acta》2007,452(2):85-105
What is really measured in dynamic calorimetric experiments is still an open question. This paper is devoted to this question, which can be usefully envisaged by means of macroscopic non-equilibrium thermodynamics. From the pioneer work of De Donder on chemical reactions and with other authors along the 20th century, the question is tackled under an historical point of view. A special attention is paid about the notions of frequency dependent complex heat capacity and entropy production due to irreversible processes occurring during an experiment. This phenomenological approach based on thermodynamics, not widely spread in the literature of calorimetry, could open significant perspectives on the study of macro-systems undergoing physico-chemical transformations probed by dynamic calorimetry. 相似文献