全文获取类型
收费全文 | 9832篇 |
免费 | 674篇 |
国内免费 | 1077篇 |
专业分类
化学 | 7338篇 |
晶体学 | 85篇 |
力学 | 139篇 |
综合类 | 45篇 |
数学 | 78篇 |
物理学 | 1319篇 |
综合类 | 2579篇 |
出版年
2024年 | 26篇 |
2023年 | 70篇 |
2022年 | 209篇 |
2021年 | 247篇 |
2020年 | 242篇 |
2019年 | 228篇 |
2018年 | 152篇 |
2017年 | 205篇 |
2016年 | 316篇 |
2015年 | 315篇 |
2014年 | 330篇 |
2013年 | 728篇 |
2012年 | 411篇 |
2011年 | 482篇 |
2010年 | 359篇 |
2009年 | 474篇 |
2008年 | 543篇 |
2007年 | 678篇 |
2006年 | 596篇 |
2005年 | 528篇 |
2004年 | 524篇 |
2003年 | 428篇 |
2002年 | 368篇 |
2001年 | 323篇 |
2000年 | 339篇 |
1999年 | 319篇 |
1998年 | 243篇 |
1997年 | 281篇 |
1996年 | 238篇 |
1995年 | 249篇 |
1994年 | 236篇 |
1993年 | 170篇 |
1992年 | 189篇 |
1991年 | 119篇 |
1990年 | 84篇 |
1989年 | 73篇 |
1988年 | 87篇 |
1987年 | 49篇 |
1986年 | 30篇 |
1985年 | 23篇 |
1984年 | 12篇 |
1983年 | 4篇 |
1982年 | 15篇 |
1981年 | 10篇 |
1980年 | 8篇 |
1978年 | 3篇 |
1977年 | 3篇 |
1976年 | 4篇 |
1974年 | 3篇 |
1973年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
81.
Relationships have been established between the average conversion degree and the dissociation time for polydisperse granular
material, taking its grain size distribution into account. It has been checked in which cases the kinetic curves obtained
by a numerical solution can be described in terms of KEKAM equation.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
82.
83.
Yatsimirskii V. K. Oleksenko L. P. Lutsenko L. V. 《Theoretical and Experimental Chemistry》2004,40(1):44-51
We have studied the kinetic behavior of oxidation of carbon monoxide on Co-containing zeolite ZSM-5. We have shown that the kinetic curves obtained for the dependence of the reaction rate on the reagent concentration can be described by an Eley–Rideal mechanism, which assumes that oxygen can be adsorbed on the surface of the catalyst in both atomic and molecular form, followed by reaction of CO from the gas phase with the adsorbed oxygen. 相似文献
84.
用DSC研究纯三水铝石溶出动力学 总被引:1,自引:0,他引:1
在DSC上研究了NaOH溶液中合成三水铝石的溶出过程动力学。应用非等温反应动力学模型计算了动力学参数,分析和确定了反应机理。模型计算结果与用DSC测得的结果吻合。 相似文献
85.
[H+]在0.01~0.70mol?L-1范围内,离子强度为1.00mol?L-1,[Fe(III)]>>[配体]、[H+]>>[配体]的条件下,研究了Fe(III)与2,3-二羟基苯磺酸钠(Tiron)的配位反应.发现当[H+]≤3.00×10-2mol?L-1时,[Fe(III)]2对反应速率有明显的贡献.求得了相关反应的动力学参数,从而揭示了FeOH2+和FeOH24+与Tiron配位的解离反应途径及FeOH32+的缔合反应机制,并提出了该配位反应的可能机理. 相似文献
86.
Relationships between average degree of transformation and time of dissociation were derived for polydisperse granular materials
with account to the type of grain size distribution. It has been checked, under what conditions the kinetic curves obtained
by numeric solution of those relationships may be described in terms of equations D1 α2=kt
, F2 [1/(1 - α) - 1 =kt] and F3 [1/(1 - α)2 - 1=kt].
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
87.
Bagiyan G. A. Koroleva I. K. Soroka N. V. Ufimtsev A. V. 《Russian Chemical Bulletin》2003,52(5):1135-1141
Side self-oxidation of thiols was studied. It was found that these reactions in neutral and alkaline solutions are induced by impurities of variable-valence metals. The ability of transition metals to catalyze oxidation of thiols changes in the order Cu > Mn > Fe > Ni Co. The plot of the self-oxidation rate vs. pH passes through a maximum whose position on the pH scale depends on both the nature of metal and the structure of the thiol oxidized. For thiols having different structures, the kinetic orders in reactions catalyzed by copper ions differently vary with pH, which is apparently associated with the formation of complexes possessing different catalytic activity. 相似文献
88.
A thermal analysis study on the reduction of iron oxide rich slags under different conditions is presented in this paper. The effects of important process variables such as time, temperature, lime-silica ratio, FeO level in slag etc. are discussed. It is shown that the mechanism of reduction by externally added graphite is different from that by a carbon saturated bath although the activation energy values are similar. 相似文献
89.
J. A. Azizi D. Dollimore P. J. Dollimore G. R. Heal P. Manley W. A. Kneller W. Jin Yong 《Journal of Thermal Analysis and Calorimetry》1993,40(2):831-847
In this study a relationship between the surface and textural properties of carbon blacks and the gasification process induced thermally in air is noted. A temperature jump method was used to follow the gasification in air and to establish the relevant Arrhenius parameters. This can be associated with the activity of ‘basal’ plane carbon atoms as well as ‘edge’ carbon atoms at the surface. This is based on a model of carbon black structure consisting of the irregular packing of small graphite carbon structures. The carbon black surface was measured using a single measurement of adsorption based essentially on the BET volumetric method. The carbon black surface had a rate of oxidation per unit are which clearly indicated that the lower area carbon blacks had a predominately active area of ‘edge’ atoms at the surface while the surface of the higher area carbon blacks had a predominate amount of ‘basal’ plane graphite carbon atoms. 相似文献
90.
The rapid-scanning capability of FTIR instrumentation has revitalized the field of vibrational spectroscopy in polymer research and will be discussed with reference to the study of polyurethane kinetics, the temperature dependence of hydrogen bonding in polyamide 6 and strain-induced crystallization in a polydimethylsiloxane elastomer. 相似文献