全文获取类型
收费全文 | 89篇 |
免费 | 1篇 |
专业分类
化学 | 64篇 |
数学 | 12篇 |
物理学 | 14篇 |
出版年
2024年 | 1篇 |
2022年 | 3篇 |
2021年 | 6篇 |
2020年 | 4篇 |
2019年 | 3篇 |
2018年 | 1篇 |
2017年 | 4篇 |
2016年 | 2篇 |
2015年 | 4篇 |
2014年 | 4篇 |
2013年 | 7篇 |
2012年 | 5篇 |
2011年 | 3篇 |
2010年 | 2篇 |
2009年 | 7篇 |
2008年 | 6篇 |
2007年 | 2篇 |
2006年 | 5篇 |
2005年 | 3篇 |
2004年 | 6篇 |
2003年 | 1篇 |
2002年 | 2篇 |
2001年 | 2篇 |
2000年 | 1篇 |
1996年 | 1篇 |
1994年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
排序方式: 共有90条查询结果,搜索用时 0 毫秒
31.
Agn Mikelionien Danut Vai
iukynien Aras Kantautas Algirdas Radzevi
ius Katarzyna Zarbska 《Molecules (Basel, Switzerland)》2021,26(10)
In this study, straetlingite-based sorbents were used for NH4+ ion removal from a synthetic aqueous solution and from the wastewater of an open recirculation African catfish farming system. This study was performed using column experiments with four different filtration rates (2, 5, 10, and 15 mL/min). It was determined that breakthrough points and sorption capacity could be affected by several parameters such as flow rate and mineral composition of sorption materials. In the synthetic aqueous solution, NH4+ removal reached the highest sorption capacity, i.e., 0.341 mg/g with the S30 sorbent at a filtration rate of 10 mL/min and an initial concentration of 10 mg/L of NH4+ ions. It is important to emphasize that, in this case, the Ce/C0 ratio of 0.9 was not reached after 420 min of sorption. It was also determined that the NH4+ sorption capacity was influenced by phosphorus. In the wastewater, the NH4+ sorption capacity was almost seven times lower than that in the synthetic aqueous solution. However, it should be highlighted that the P sorption capacity reached 0.512 mg/g. According to these results, it can be concluded that straetlingite-based sorbents can be used for NH4+ ion removal from a synthetic aqueous solution, as well as for both NH4+ and P removal from industrial wastewater. In the wastewater, a significantly higher sorption capacity of the investigated sorbents was detected for P than for NH4+. 相似文献
32.
Algirdas C. Poshkus 《Journal of heterocyclic chemistry》1979,16(5):1075-1076
Pentaerythritol diformal is prepared almost quantitatively in less than ten minutes by heating up to about 120° a neat mixture of pentaerythritol with a slight excess of paraformaldehyde containing catalytic amounts of a mineral acid. 相似文献
33.
Karolina Dzedulionyt Melita Veikait Vít Morvek Vida Malinauskien Greta Ra
kauskien Algirdas a
kus Asta
ukauskait Egl Arba
iauskien 《Molecules (Basel, Switzerland)》2022,27(24)
A general approach towards the synthesis of tetrahydro-4H-pyrazolo[1,5-a][1,4]diazepin-4-one, tetrahydro[1,4]diazepino[1,2-a]indol-1-one and tetrahydro-1H-benzo[4,5]imidazo[1,2-a][1,4]diazepin-1-one derivatives was introduced. A regioselective strategy was developed for synthesizing ethyl 1-(oxiran-2-ylmethyl)-1H-pyrazole-5-carboxylates from easily accessible 3(5)-aryl- or methyl-1H-pyrazole-5(3)-carboxylates. Obtained intermediates were further treated with amines resulting in oxirane ring-opening and direct cyclisation—yielding target pyrazolo[1,5-a][1,4]diazepin-4-ones. A straightforward two-step synthetic approach was applied to expand the current study and successfully functionalize ethyl 1H-indole- and ethyl 1H-benzo[d]imidazole-2-carboxylates. The structures of fused heterocyclic compounds were confirmed by 1H, 13C, and 15N-NMR spectroscopy and HRMS investigation. 相似文献
34.
Algirdas Audzijonis Gediminas Gaigalas Leonardas Žigas Audrius Pauliukas Raimundas Žaltauskas Aurimas Čerškus Jurgis Narusis 《Central European Journal of Physics》2005,3(3):382-394
This paper presents the theoretical investigation of energy levels of valence bands (VB) and core levels (CL) of the ferroelectric
SbSl single crystals in antiferroelectric and ferroelectric phases. Since the best approximation for the deep VB levels is
a calculation by the Hartree-Fock method, the molecular model of a SbSI crystal was used for calculations. This model of the
crystal was also used for calculations of the total density of states. It was found that the VB and CL of this ferroelectric
semiconductor are sensitive to the small lattice distortion at the phase transition, and that an average of the total density
of states, when all atoms participate in oscillations of all normal modes, are more similar to the experimental X-ray photoelectron
spectra (XPS). The experimental splitting of CL obtained by XPS was compared with the theoretically calculated one by two
different methods. The cluster model calculations showed that the splitting of the CL in SbSI might be caused by photoelectron
emission from the atoms, which have different valence state, at the surface. 相似文献
35.
36.
37.
Vytas MartynaitisRasa Steponavi?iūt? Sonata Krikštolaityt?Joana Solovjova Sven Mangelinckx Norbert De KimpeWolfgang Holzer Algirdas Ša?kus 《Tetrahedron》2011,67(21):3945-3953
1-Hydroxy-9,9a-dihydro-1H-imidazo[1,2-a]indol-2(3H)-ones, as a new type of azaheterocyclic hydroxamic acids, have been synthesized regioselectively from 1-carbamoylmethyl- or 1-(methoxycarbonyl)methyl-2,3,3-trimethyl-3H-indolium salts by reaction with hydroxylamine in the presence of a strong base. The alkylation and reduction with sodium borohydride of these novel heterocycles have been investigated. When treated with protic acids 1-hydroxy- or 1-alkoxy-9,9a-dihydro-1H-imidazo[1,2-a]indol-2(3H)-ones underwent ring opening of the imidazolidine to afford 1-[2-(hydroxyamino)-2-oxoethyl]-2,3,3-trimethyl-3H-indolium salts. The structural assignments are based on extensive 1H, 13C and 15N NMR spectroscopic studies and single crystal X-ray analyses. 相似文献
38.
We consider a sequence of distributions defined via the generalized divisor function. We describe the possible limit distributions and estimate the remainder terms. 相似文献
39.
Malashchonak Мikalai Streltsov Eugene Mazanik Alexander Korolik Olga Kulak Anatoly Puzikova Darya Dergacheva Margarita Selskis Algirdas 《Journal of Solid State Electrochemistry》2020,24(2):401-409
Journal of Solid State Electrochemistry - Nanostructured n-Bi2O3/p-CuBi2O4/p-CuO photocathodes with incident photon-to-current conversion efficiency IPCEmax = 70%... 相似文献