全文获取类型
收费全文 | 180篇 |
免费 | 3篇 |
专业分类
化学 | 116篇 |
晶体学 | 4篇 |
数学 | 22篇 |
物理学 | 41篇 |
出版年
2022年 | 5篇 |
2021年 | 9篇 |
2020年 | 2篇 |
2019年 | 4篇 |
2018年 | 7篇 |
2017年 | 1篇 |
2016年 | 3篇 |
2015年 | 6篇 |
2014年 | 13篇 |
2013年 | 17篇 |
2012年 | 26篇 |
2011年 | 11篇 |
2010年 | 6篇 |
2009年 | 10篇 |
2008年 | 10篇 |
2007年 | 12篇 |
2006年 | 4篇 |
2005年 | 10篇 |
2004年 | 4篇 |
2003年 | 4篇 |
2002年 | 1篇 |
1998年 | 1篇 |
1996年 | 2篇 |
1995年 | 2篇 |
1992年 | 2篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1985年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有183条查询结果,搜索用时 15 毫秒
61.
Oksana Desiatkina Martin Msching Nicoleta Anghel Ghalia Boubaker Yosra Amdouni Andrew Hemphill Julien Furrer Emilia Punescu 《Molecules (Basel, Switzerland)》2022,27(23)
Aiming toward compounds with improved anti-Toxoplasma activity by exploiting the parasite auxotrophies, a library of nucleobase-tethered trithiolato-bridged dinuclear ruthenium(II)-arene conjugates was synthesized and evaluated. Structural features such as the type of nucleobase and linking unit were progressively modified. For comparison, diruthenium hybrids with other type of molecules were also synthesized and assessed. A total of 37 compounds (diruthenium conjugates and intermediates) were evaluated in a primary screening for in vitro activity against transgenic Toxoplasma gondii tachyzoites constitutively expressing β-galactosidase (T. gondii β-gal) at 0.1 and 1 µM. In parallel, the cytotoxicity in non-infected host cells (human foreskin fibroblasts, HFF) was determined by alamarBlue assay. Twenty compounds strongly impairing parasite proliferation with little effect on HFF viability were subjected to T. gondii β-gal half maximal inhibitory concentration determination (IC50) and their toxicity for HFF was assessed at 2.5 µM. Two promising compounds were identified: 14, ester conjugate with 9-(2-oxyethyl)adenine, and 36, a click conjugate bearing a 2-(4-(hydroxymethyl)-1H-1,2,3-triazol-1-yl)methyl substituent, with IC50 values of 0.059 and 0.111 µM respectively, significantly lower compared to pyrimethamine standard (IC50 = 0.326 µM). Both 14 and 36 exhibited low toxicity against HFF when applied at 2.5 µM and are candidates for potential treatment options in a suitable in vivo model. 相似文献
62.
In this work we consider two integral operators. The integral operators were constructed on the basis of the fact that the number of functions from the composition of the operators is the entire part of a complex number modulus. 相似文献
63.
Journal of Optimization Theory and Applications - This paper aims at solving Zermelo’s navigation problem on conformally flat Riemannian manifolds admitting a ship’s variable... 相似文献
64.
M. Elisa Cristiana Grigorescu Ileana Vasiliu M. Bulinski V. Kuncser Dana Predoi G. Filoti Aurelia Meghea Nicoleta Iftimie Maria Giurginca C. Onose 《Optical and Quantum Electronics》2007,39(4-6):523-531
The paper deals with optical and electronic properties of the aluminophosphate glasses containing Fe–Mn and Fe–Cr ion pairs in different concentration. The influence of the mixed alkali ions over the electronic properties has been investigated. The optical behavior (optical transmission) of the glass samples has been studied by UV-VIS spectroscopy and the refractive index dependency on wavelength has been discussed. The transmission spectra show features specific for the doping transition ions (TM), revealing different oxidation states of iron (Fe2+/Fe3+), manganese (Mn2+/Mn3+) and chromium (Cr3+/Cr6+) in the vitreous network. Mössbauer spectroscopy offers information regarding the TM oxidation states, redox processes and the iron coordination symmetry in the vitreous network. In the case of Fe–Mn doped glasses, the percentage of Fe2+ is about 40% and a doubled iron content leads to an increasing of Fe2+ percentage up to 53%. The replacing of lithium ions by natrium ions (mixed alkali effect) provides an increasing of the Fe2+ percentage up to 56%. The occurrence of the tetrahedral or octahedral symmetry of Fe2+ ions bonded by O2? ions depends on the transition ion nature and Li+/Na+ ratio. Infrared absorption spectra of the pair transition ions-doped aluminophosphate glasses reveal optical phonons specific for the phosphate glass matrix. 相似文献
65.
Daniel Ioan Hădărugă Nicoleta Gabriela Hădărugă Gallia Butnaru Călin Tatu Alexandra Gruia 《Journal of inclusion phenomena and macrocyclic chemistry》2010,68(1-2):155-164
The paper presents a comparative thermal and oxidative stability study between nicotine/β-cyclodextrin microparticles and commercial nicotine. It is well known that the nicotine is the bioactive compound in formulations used for smoking cessation and no studies among the stability of nicotine in cyclodextrin-containing formulations were reported. The non-enzymatic and enzymatic oxidation of nicotine can lead to cotinine (an alkaloid/metabolite with a lower toxicity), but another way is the obtaining of the cancerigene N-nitroso-nicotine derivatives by nornicotine derivative intermediates (like nornicotine and myosmine). The present study demonstrates the protecting capacity of β-cyclodextrin for commercial nicotine against thermal and oxidative factors: for the non-complexed nicotine the thermal and oxidative degradation led to a decrease of the relative concentration of nicotine from 96 to 92% for an increasing temperature from 30 to 90 °C (in the presence of air at normal pressure), with an increase of the relative concentration of the corresponding oxidized compounds (like cotinine and furthermore myosmine up to 0.7%, and up to 4.7%, respectively). For the nicotine/β-cyclodextrin complex the interaction selectivity was higher for nicotine and the stability of this bioactive compound against oxidation was also higher in comparison with the non-complexed nicotine (around 98% in all cases). 相似文献
66.
M. Eugenia Aldea 《Thermochimica Acta》2005,429(2):233-239
Excess molar volumes, VE, isentropic compressibility deviations, ΔκS, and excess molar enthalpies, HE, for the binary mixtures 2-methyl-tetrahydrofuran with 1-chlorobutane, 2-chlorobutane, 2-methyl-1-chloropropane and 2-methyl-2-chloropropane have been determined at temperatures 298.15 and 313.15 K, excess molar enthalpies were only measured at 298.15 K. We have applied the Prigogine-Flory-Patterson (PFP) theory to these mixtures at 298.15 K. 相似文献
67.
Muresan N Weyhermüller T Wieghardt K 《Dalton transactions (Cambridge, England : 2003)》2007,(39):4390-4398
68.
69.
Graziela Virginia Guslicov Mariana Coarna Alice Pop Cristina Vlad Nicoleta Vlad 《Accreditation and quality assurance》2009,14(10):541-546
Since 1988, over 40 laboratories representing research institutes, cement plants, pre-cast units, hydro plant construction companies, industrial construction companies, building companies, etc. from nine countries—Romania, Republic of Moldova, Croatia, Serbia, Macedonia, Bulgaria, Hungary, Ukraine and Lebanon—take part every year in an interlaboratory test organized by our laboratory. The subject of the interlaboratory test for cement was 37 laboratory tests: 12 chemical determinations, 7 physical tests and 9 mechanical tests carried out with 2 types of sand, from CEPROCIM and from each participant laboratory. The paper presents the evolution of two statistical parameters (standard deviation of reproducibility and/or coefficient of variation) for a period of 20 years and for 11 laboratory tests. The results strongly prove that interlaboratory test is one of the most efficient tools to establish a common language for all the participant laboratories performing cement testing procedures. 相似文献
70.