全文获取类型
收费全文 | 1306篇 |
免费 | 47篇 |
国内免费 | 3篇 |
专业分类
化学 | 852篇 |
晶体学 | 5篇 |
力学 | 29篇 |
数学 | 161篇 |
物理学 | 309篇 |
出版年
2023年 | 10篇 |
2022年 | 48篇 |
2021年 | 50篇 |
2020年 | 32篇 |
2019年 | 30篇 |
2018年 | 44篇 |
2017年 | 37篇 |
2016年 | 51篇 |
2015年 | 41篇 |
2014年 | 59篇 |
2013年 | 90篇 |
2012年 | 86篇 |
2011年 | 90篇 |
2010年 | 79篇 |
2009年 | 67篇 |
2008年 | 85篇 |
2007年 | 74篇 |
2006年 | 69篇 |
2005年 | 41篇 |
2004年 | 43篇 |
2003年 | 22篇 |
2002年 | 24篇 |
2001年 | 27篇 |
2000年 | 8篇 |
1999年 | 24篇 |
1998年 | 15篇 |
1997年 | 12篇 |
1996年 | 11篇 |
1995年 | 16篇 |
1994年 | 10篇 |
1993年 | 9篇 |
1992年 | 5篇 |
1991年 | 3篇 |
1990年 | 8篇 |
1989年 | 8篇 |
1988年 | 3篇 |
1987年 | 3篇 |
1986年 | 4篇 |
1985年 | 5篇 |
1984年 | 4篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1975年 | 1篇 |
排序方式: 共有1356条查询结果,搜索用时 734 毫秒
41.
42.
43.
44.
Rodrigues Filipe Agra Agostinho Hvattum Lars Magnus Requejo Cristina 《Journal of Heuristics》2021,27(3):459-496
Journal of Heuristics - Proximity search is an iterative method to solve complex mathematical programming problems. At each iteration, the objective function of the problem at hand is replaced by... 相似文献
45.
Amanda C.R. Koike Amanda G. Santillo Flávio T. Rodrigues Renato C. Duarte Anna Lucia C.H. Villavicencio 《Radiation Physics and Chemistry》2012,81(8):1068-1070
The minimally processed food provided the consumer with a product quality, safety and practicality. However, minimal processing of food does not reduce pathogenic population of microorganisms to safe levels. Ionizing radiation used in low doses is effective to maintain the quality of food, reducing the microbiological load but rather compromising the nutritional values and sensory property. The association of minimal processing with irradiation could improve the quality and safety of product. The purpose of this study was to evaluate the effectiveness of low-doses of ionizing radiation on the reduction of microorganisms in minimally processed foods. The results show that the ionizing radiation of minimally processed vegetables could decontaminate them without several changes in its properties. 相似文献
46.
Manuel J. Rocha Armada Paulo J. Pereira Artur Rodrigues 《Mathematics and Financial Economics》2013,7(4):509-530
This paper presents a real options model to value the option to invest in a project contingent on two stochastic factors. A general sensitivity analysis is conducted highlighting the importance of the variance and correlation between the two variables. A higher correlation is shown to increase always the values of the trigger, the active project and the option. The impact of uncertainty is more complex and depends on the assumption about which variables adjust and the correlation between the variables and the market. 相似文献
47.
Ariana Borges Souza Monique Rodrigues Moreira Carly Henrique Gambeta Borges Marília Rodrigues Simão Jairo Kenupp Bastos João Paulo Barreto de Sousa Sérgio Ricardo Ambrosio Rodrigo Cassio Sola Veneziani 《Biomedical chromatography : BMC》2013,27(3):280-283
The Copaifera species (Leguminoseae) are popularly known as ‘copaíba’ or ‘copaíva’ and are grown in the states of Amazonas, Pará and Ceará in northern Brazil. The oleoresins obtained from these species have been extensively used owing to their pharmacological potential and their application in cosmetic and pharmaceutical preparations. In the present study, the development and validation of a novel, rapid and efficient RP‐HPLC methodology for the analysis of the diterpene (?)‐copalic acid (CA), pointed out as the only chemical marker of the Copaifera genus, are described. The regression equation (Y = 26,707x ? 29,498) was obtained with good linearity (r2 = 0.9993) and the limits of quantification and detection were 9.182 and 3.032 µg/mL, respectively. The precision and the accuracy of the method were adequate (lower than 4%). Finally, the validation parameters evaluated were satisfactorily met, so the developed method represents a suitable tool for application in the quality control of such natural products. Further studies aiming to develop analytical methodologies for each Copaifera species using a more representative number of chemical markers should be performed. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
48.
49.
Quantitative analysis of biogenic polyamines in distilled drinks by direct electrospray ionization tandem mass spectrometry using a nanocontainer 下载免费PDF全文
50.