全文获取类型
收费全文 | 94篇 |
免费 | 1篇 |
国内免费 | 1篇 |
专业分类
化学 | 46篇 |
力学 | 5篇 |
数学 | 25篇 |
物理学 | 20篇 |
出版年
2023年 | 1篇 |
2022年 | 1篇 |
2021年 | 4篇 |
2019年 | 4篇 |
2018年 | 3篇 |
2017年 | 2篇 |
2016年 | 1篇 |
2015年 | 7篇 |
2014年 | 1篇 |
2013年 | 9篇 |
2012年 | 3篇 |
2011年 | 10篇 |
2010年 | 11篇 |
2009年 | 7篇 |
2008年 | 6篇 |
2007年 | 7篇 |
2006年 | 5篇 |
2005年 | 4篇 |
2003年 | 3篇 |
2002年 | 1篇 |
2001年 | 1篇 |
1996年 | 1篇 |
1989年 | 1篇 |
1986年 | 1篇 |
1972年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有96条查询结果,搜索用时 15 毫秒
91.
92.
The Ramanujan Journal - In this note, using the well-known series representation for the Clausen function, we also provide some new representations of Apery’s constant $$\zeta (3)$$ . In... 相似文献
93.
Cezar A. Bizzi Juliano S. BarinEdivaldo E. Garcia Joaquim A. NóbregaValderi L. Dressler Erico M.M. Flores 《Spectrochimica Acta Part B: Atomic Spectroscopy》2011,66(5):394-398
The feasibility of using diluted HNO3 solutions under oxygen pressure for decomposition of whole and non-fat milk powders and whey powder samples has been evaluated. Digestion efficiency was evaluated by determining the carbon content in solution (digests) and the determination of Ca, Cd, Cu, Fe, K, Mg, Mn, Mo, Na, Pb and Zn was performed by inductively coupled plasma optical emission spectrometry and Hg by chemical vapor generation coupled to inductively coupled plasma mass spectrometry. Samples (up to 500 mg) were digested using HNO3 solutions (1 to 14 mol L− 1) and the effect of oxygen pressure was evaluated between 2.5 and 20 bar. It was possible to perform the digestion of 500 mg of milk powder using 2 mol L− 1 HNO3 with oxygen pressure ranging from 7.5 to 20 bar with resultant carbon content in digests lower than 1700 mg L− 1. Using optimized conditions, less than 0.86 mL of concentrated nitric acid (14 mol L− 1) was enough to digest 500 mg of sample. The accuracy was evaluated by determination of metal concentrations in certified reference materials, which presented an agreement better than 95% (Student's t test, P < 0.05) for all the analytes. 相似文献
94.
Cezar A. Bizzi Erico M.M. Flores Juliano S. Barin Edivaldo E. Garcia Joaquim A. Nóbrega 《Microchemical Journal》2011,99(2):193-196
Sample preparation has a long history when thinking about the conversion of solid samples to representative solutions using concentrated acid solutions and high temperature. However, chemical sciences are evolving to cleaner procedures and surely, sample preparation must follow these steps. The advent of microwave-assisted digestion led to new devices that have allowed the development of new procedures based on diluted solutions of nitric acid and more recently the use of oxygen as a reagent. No doubts oxygen has played a major role in most dry and wet digestion procedures for digestion of organic samples, but its role was improved by using it to regenerate nitric acid and consequently decreasing the volumes of acids needed to promote efficient digestions. These aspects were clearly demonstrated by comparing the efficiency of whole milk powder digestions under different pressures of oxygen, atmospheric air or inert argon atmosphere. The pressure profiles in these conditions were also evaluated and indicate the regeneration process. The efficiency of the digestion process using oxygen was demonstrated by measuring residual carbon contents and residual acidity in digests and it was shown that both parameters were fully compatible with requirements of modern instrumental analysis without any further extensive dilution of the digestates. 相似文献
95.
A. F. Orlov L. A. Balagurov I. V. Kulemanov N. S. Perov E. A. Gan’shina L. Yu. Fetisov A. Rogalev A. Smekhova J. C. Cezar 《Physics of the Solid State》2011,53(3):482-484
The possibility of creating room-temperature intrinsic ferromagnetism in a highly doped oxide semiconductor has been investigated.
The results indicate that such state of a ferromagnetic semiconductor can be achieved by magnetron sputtering deposition of
a semiconductor oxide doped with a transition metal followed by low-temperature vacuum annealing. 相似文献
96.
Júlio C. Cezar Narcizo M. Souza‐Neto Cínthia Piamonteze Edilson Tamura Flávio Garcia Edson J. Carvalho Régis T. Neueschwander Aline Y. Ramos Hélio C. N. Tolentino Alberto Caneiro Nestor E. Massa Maria Jesus Martinez‐Lope Jose Antonio Alonso Jean‐Paul Itié 《Journal of synchrotron radiation》2010,17(1):93-102
An energy‐dispersive X‐ray absorption spectroscopy beamline mainly dedicated to X‐ray magnetic circular dichroism (XMCD) and material science under extreme conditions has been implemented in a bending‐magnet port at the Brazilian Synchrotron Light Laboratory. Here the beamline technical characteristics are described, including the most important aspects of the mechanics, optical elements and detection set‐up. The beamline performance is then illustrated through two case studies on strongly correlated transition metal oxides: an XMCD insight into the modifications of the magnetic properties of Cr‐doped manganites and the structural deformation in nickel perovskites under high applied pressure. 相似文献