全文获取类型
收费全文 | 207864篇 |
免费 | 2115篇 |
国内免费 | 601篇 |
专业分类
化学 | 104686篇 |
晶体学 | 3426篇 |
力学 | 9427篇 |
综合类 | 5篇 |
数学 | 22789篇 |
物理学 | 70247篇 |
出版年
2021年 | 1730篇 |
2020年 | 1893篇 |
2019年 | 2085篇 |
2018年 | 2807篇 |
2017年 | 2679篇 |
2016年 | 3888篇 |
2015年 | 2407篇 |
2014年 | 3762篇 |
2013年 | 9319篇 |
2012年 | 7560篇 |
2011年 | 9040篇 |
2010年 | 6219篇 |
2009年 | 6069篇 |
2008年 | 8091篇 |
2007年 | 8246篇 |
2006年 | 7889篇 |
2005年 | 7025篇 |
2004年 | 6511篇 |
2003年 | 5734篇 |
2002年 | 5564篇 |
2001年 | 6486篇 |
2000年 | 4986篇 |
1999年 | 3839篇 |
1998年 | 3069篇 |
1997年 | 3095篇 |
1996年 | 2847篇 |
1995年 | 2652篇 |
1994年 | 2531篇 |
1993年 | 2416篇 |
1992年 | 2763篇 |
1991年 | 2715篇 |
1990年 | 2644篇 |
1989年 | 2439篇 |
1988年 | 2483篇 |
1987年 | 2485篇 |
1986年 | 2312篇 |
1985年 | 2993篇 |
1984年 | 3245篇 |
1983年 | 2664篇 |
1982年 | 2833篇 |
1981年 | 2811篇 |
1980年 | 2673篇 |
1979年 | 2756篇 |
1978年 | 2843篇 |
1977年 | 2847篇 |
1976年 | 2907篇 |
1975年 | 2692篇 |
1974年 | 2671篇 |
1973年 | 2807篇 |
1972年 | 1778篇 |
排序方式: 共有10000条查询结果,搜索用时 406 毫秒
21.
Smirnova T. D. Zhelobitskaya E. A. Danilina T. G. 《Journal of Analytical Chemistry》2022,77(8):1000-1004
Journal of Analytical Chemistry - Silver nanoparticles modified with Eu3+ ions increase the intensity of the fluorescence signal by a factor of 125 in an analytical system containing doxycycline as... 相似文献
22.
Ajit Kumar Singh Seulgi Ji Baghendra Singh Chittaranjan Das Heechae Choi Prashanth W. Menezes Arindam Indra 《Materials Today Chemistry》2022
Herein, we report a Mott-Schottky catalyst by entrapping cobalt nanoparticles inside the N-doped graphene shell (Co@NC). The Co@NC delivered excellent oxygen evolution activity with an overpotential of merely 248 mV at a current density of 10 mA cm–2 with promising long-term stability. The importance of Co encapsulated in NC has further been demonstrated by synthesizing Co nanoparticles without NC shell. The synergy between the hexagonal close-packed (hcp) and face-centered cubic (fcc) Co plays a major role to improve the OER activity, whereas the NC shell optimizes the electronic structure, improves the electron conductivity, and offers a large number of active sites in Co@NC. The density functional theory calculations have revealed that the hcp Co has a dominant role in the surface reaction of electrocatalytic oxygen evolution, whereas the fcc phase induces the built-in electric field at the interfaces with N-doped graphene to accelerate the H+ ion transport. 相似文献
23.
Ibotov Sh. Kh. Yuldasheva N. K. Mukarramov N. I. Zakirova R. P. Gusakova S. D. 《Chemistry of Natural Compounds》2022,58(4):728-731
Chemistry of Natural Compounds - 相似文献
24.
Journal of Experimental and Theoretical Physics - This article presents a survey of many nontrivial effects connected with the coupling of electric and magnetic degrees of freedom in... 相似文献
25.
26.
27.
28.
29.
30.
Dr. Antonio M. Rodríguez Dr. Pilar Prieto Prof. Antonio de la Hoz Prof. Ángel Díaz-Ortiz D. Raúl Martín Prof. José I. García 《ChemistryOpen》2015,4(3):308-317
The aim of this work was to determine the parameters that have decisive roles in microwave-assisted reactions and to develop a model, using computational chemistry, to predict a priori the type of reactions that can be improved under microwaves. For this purpose, a computational study was carried out on a variety of reactions, which have been reported to be improved under microwave irradiation. This comprises six types of reactions. The outcomes obtained in this study indicate that the most influential parameters are activation energy, enthalpy, and the polarity of all the species that participate. In addition to this, in most cases, slower reacting systems observe a much greater improvement under microwave irradiation. Furthermore, for these reactions, the presence of a polar component in the reaction (solvent, reagent, susceptor, etc.) is necessary for strong coupling with the electromagnetic radiation. We also quantified that an activation energy of 20–30 kcal mol−1 and a polarity (μ) between 7–20 D of the species involved in the process is required to obtain significant improvements under microwave irradiation. 相似文献