全文获取类型
收费全文 | 22421篇 |
免费 | 1940篇 |
国内免费 | 2619篇 |
专业分类
化学 | 16877篇 |
晶体学 | 170篇 |
力学 | 1036篇 |
综合类 | 62篇 |
数学 | 4225篇 |
物理学 | 4610篇 |
出版年
2024年 | 168篇 |
2023年 | 882篇 |
2022年 | 955篇 |
2021年 | 911篇 |
2020年 | 2154篇 |
2019年 | 1588篇 |
2018年 | 1402篇 |
2017年 | 1289篇 |
2016年 | 1414篇 |
2015年 | 1218篇 |
2014年 | 1469篇 |
2013年 | 4064篇 |
2012年 | 1349篇 |
2011年 | 893篇 |
2010年 | 727篇 |
2009年 | 726篇 |
2008年 | 742篇 |
2007年 | 703篇 |
2006年 | 606篇 |
2005年 | 617篇 |
2004年 | 617篇 |
2003年 | 463篇 |
2002年 | 337篇 |
2001年 | 280篇 |
2000年 | 216篇 |
1999年 | 193篇 |
1998年 | 182篇 |
1997年 | 135篇 |
1996年 | 111篇 |
1995年 | 117篇 |
1994年 | 86篇 |
1993年 | 91篇 |
1992年 | 38篇 |
1991年 | 36篇 |
1990年 | 28篇 |
1989年 | 15篇 |
1988年 | 18篇 |
1987年 | 14篇 |
1986年 | 10篇 |
1985年 | 12篇 |
1984年 | 15篇 |
1983年 | 13篇 |
1982年 | 11篇 |
1981年 | 17篇 |
1980年 | 7篇 |
1979年 | 11篇 |
1978年 | 6篇 |
1977年 | 7篇 |
1973年 | 3篇 |
1972年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
51.
Zdeněk Slanina 《Journal of Cluster Science》2004,15(1):3-11
Computational findings of temperature increase of clustering degree in saturated vapors are analyzed. A thermodynamic proof is presented and a simple criterion derived. Illustrations are based on saturated steam, magnesium and carbon vapor. The results are applicable to synthesis of fullerenes, metallofullerenes, and heterofullerenes, chemical vapor deposition technique, or atmospheric chemistry. 相似文献
52.
Organic chelating reagent influences upon the redox adsorption of activated carbon fibertowards Au3- were systematically investigated. The experimental results indicated that the presenceof organic chelating reagent on activated carbon fiber strongly affects adsorption capacity ofactivated carbon fiber towards Au3+. The reduction-adsorption amount of Au3+ increased three timesby the presence of 8-quinolinol. Furthermore, The reduction-adsorption amount of Au3+ depended onthe pH value of adsorption and temperature. 相似文献
53.
A. Torrisi P. Horák J. Vacík A. Cannavò G. Ceccio J. Vaniš 《Phosphorus, sulfur, and silicon and the related elements》2020,195(11):932-935
AbstractOn the perspective to develop CuO–TiO2 MOS, multilayered Cu and Ti thin layers were alternatively deposited on silicon wafers using 25?keV Ar?+?ion beam sputtering and, subsequently, oxidized by thermal annealing in air at 400?°C for 24?h. The deposited films have variable ratios of the Cu and Ti % at. One of the main goal is to obtain such multilayers avoiding the presence of Cu–Ti–O compounds. The samples were characterized in terms of composition (by RBS and SIMS analyses) and morphology (by AFM and SEM investigations). In particular, SIMS maps allows to observe the spatial distribution and thickness of each phase of the Cu/Ti multilayers, and further to observe Cu diffusion and mixing with Ti, as well as phase separation of CuO and TiO2 in the samples. The reasons of this effect represent an open issue that has to investigated, in order to improve the MOS fabrication. 相似文献
54.
Yu. P. Kudryavtsev S. E. Evsyukov M. B. Guseva V. G. Babaev V. V. Khvostov 《Russian Chemical Bulletin》1993,42(3):399-413
The history of the discovery of carbyne, the chemical and physical methods used to obtain it, the analysis of its structure, and some of its properties are briefly considered. The prospects for its practical applications are discussedThis publication is based on a number of works on carbyne submitted for the Russian State Prize in the field of science and technology in 1993; performed at the A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences and the M. V. Lomonosov Moscow State University.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 450–463, March, 1993. 相似文献
55.
羧基化碳纳米管嵌入石墨修饰电极对多巴胺和抗坏血酸的电催化 总被引:24,自引:0,他引:24
采用涂层和嵌入修饰法 ,将羧基化多层碳纳米管制成两种修饰电极。以多巴胺 (DA)和抗坏血酸(AA)为模型化合物 ,研究了两种修饰电极对DA和AA共存时的电催化作用。结果表明 :嵌入的方式比涂层的方式显示了更多的优点。嵌入修饰电极不仅使峰电流增加 ,并且使两者共存时的氧化峰位分离达 16 0mV ,同时 ,该电极对DA的响应灵敏于AA ,这有利于在大量的AA存在下实现对DA的测定。在 1× 10 - 3 mol/L的AA的存在下 ,还原电流的一阶导数与DA浓度在 5× 10 - 7~ 1× 10 - 4 mol/L范围内呈良好的线性关系 ;检测下限达 1× 10 - 7mol L。 相似文献
56.
《Surface and interface analysis : SIA》2006,38(9):1285-1290
The incorporation of single‐wall carbon nanotubes (SWCNTs) in cadmium arachidate film by means of the Langmuir‐Blodgett (LB) technique was investigated as a function of arachidic acid/SWCNT mass ratio at the air/water interface and in Langmuir‐Blodgett films. The behaviour at the air/water interface shows that SWCNTs act as an independent phase with respect to the cadmium arachidate. Deposition conditions are optimized when the weight ratio between the arachidic acid (AA) and SWCNTs is in the range 0.018:1 to 1:1. The general order of the LB multilayered structure was destroyed by the progressive density increase in SWCNT quantity as evidenced by X‐ray reflectivity (XRR) analysis. Scanning electron microscopy images indicated that when a multilayered structure was formed its layers consisted of SWCNT bundles stacked one over the other. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
57.
58.
59.
60.
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