全文获取类型
收费全文 | 58篇 |
免费 | 0篇 |
专业分类
化学 | 35篇 |
数学 | 17篇 |
物理学 | 6篇 |
出版年
2021年 | 3篇 |
2020年 | 2篇 |
2019年 | 2篇 |
2018年 | 2篇 |
2017年 | 2篇 |
2014年 | 6篇 |
2013年 | 2篇 |
2012年 | 3篇 |
2011年 | 1篇 |
2010年 | 1篇 |
2009年 | 4篇 |
2008年 | 3篇 |
2007年 | 3篇 |
2006年 | 2篇 |
2005年 | 2篇 |
2004年 | 1篇 |
2002年 | 7篇 |
2001年 | 1篇 |
1998年 | 2篇 |
1996年 | 1篇 |
1994年 | 1篇 |
1990年 | 1篇 |
1987年 | 1篇 |
1985年 | 1篇 |
1979年 | 1篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有58条查询结果,搜索用时 62 毫秒
41.
A new, practical, three-component method for the synthesis of 5-aza-9-deaza-adenines is developed. Aminopyrazoles react in a one-pot fashion with triethyl orthoformate and cyanamide under microwave irradiation affording 5-aza-9-deaza-adenines in good yields and high purity. The main advantages of this method are the operational simplicity, accessibility, and high efficiency. 相似文献
42.
The syntheses of 2‐amino‐s‐triazino[1,2‐a]benzimidazoles from 2‐guanidinobenzimidazoles were successfully carried out by a ring annelation reaction. The regiochemistry of the ring closure of 5‐methyl‐2‐guanidinobenzimidazole with diethyl azodicarboxylate, aldehydes, acetone, diethyl ethoxymethylenemalonate and orthoesters, leading to the formation of s‐triazine ring was studied. High regioselectivity was not observed in any of these reactions. However, the synthesis of s‐triazino[1,2‐a]benzimidazole system was found to be more regioselective than its 3,4‐dihydro analogue. NOESY experiment indicated that the compound, 2‐amino‐4,4‐dimethyl‐3,4‐dihydro‐s‐triazino[1,2‐a]benzimidazole existed predominantly as the 3,4‐dihydro tautomer in dimethyl sulfoxide. It was found to inhibit bovine dihydrofolate reductase with IC50 10.9 μM. 相似文献
43.
D. R. Khokhlov A. V. Galeeva D. E. Dolzhenko L. I. Ryabova 《Optics and Spectroscopy》2009,107(4):515-520
The properties of doped semiconductors based on lead telluride, which can be used to design highly sensitive terahertz photodetectors,
are described. It is shown that these properties allow one to develop photodetectors with much better parameters than those
of the best world analogs. 相似文献
44.
Felicia Phei Lin Lim Khai Ching Tan Giuseppe Luna Edward R.T. Tiekink Anton V. Dolzhenko 《Tetrahedron》2019,75(15):2314-2321
It was found that 3-amino-substituted 5-aminopyrazoles could be effectively prepared via hydrolytic decarboxylation of the corresponding 3,5-diaminopyrazole-4-carboxylates under microwave irradiation. The reactions required short time (4?min) and were successfully reproduced in a larger scale and under conventional heating mimicking the microwave heating pattern. X-ray crystallography identified two different types of tautomers in crystals of related 5-aminopyrazoles with p-toluidyl and p-anisidyl moieties at the position 3, respectively. 相似文献
45.
Anton V. Dolzhenko Giorgia Pastorin Anna V. Dolzhenko Wai Keung Chui 《Tetrahedron letters》2008,49(50):7180-7183
A new practical synthesis of 7-amino-substituted 1,2,4-triazolo[1,5-a][1,3,5]triazin-5-amines is developed. The triazine ring closure of 5-guanidino-3-phenyl-1,2,4-triazole with trichloroacetonitrile proceeds chemo- and regioselectively depending on the nature of the solvent. Conducting the reaction in toluene provided 7-trichloromethyl-1,2,4-triazolo[1,5-a][1,3,5]triazin-5-amine as the product, which can be further aminated efficiently with replacement of the trichloromethyl group. 相似文献
46.
S. I. Bezzubov A. A. Bilyalova I. S. Zharinova M. A. Lavrova Yu. M. Kiselev V. D. Dolzhenko 《Russian Journal of Inorganic Chemistry》2017,62(9):1197-1201
New cluster complexes of lanthanides(III) and nickel(II) [Ln{Ni(Gly)2}6]3+[Ln(NO3)6]3– have been synthesized, where Ln = La (I), Ce (II), and Pr (III); and Gly is glycinate. The structures of compounds I–III are determined by X-ray diffraction. The icosahedral cavity in the complex cation, where the lanthanide ion resides, has a fixed size independent of the nature of the central Ln(III) ion. In the complex anion, on the contrary, the Ln–O distances naturally decrease from La(III) to Pr(III). The optical properties of cationanion complexes I–III are studied. Based on the assignment in the electronic absorption spectra of the complexes, it is shown that the absorption bands are caused by d–d electronic transitions. 相似文献
47.
Technical Physics - The dielectric properties of polycrystalline fullerite films with a thickness of ~300 nm included in p-Si/C60/InGa structures under dc electric fields with a strength up to 3.3... 相似文献
48.
Kazakov A. S. Galeeva A. V. Ikonnikov A. V. Dolzhenko D. E. Ryabova L. I. Mikhailov N. N. Dvoretskiy S. A. Bannikov M. I. Danilov S. N. Khokhlov D. R. 《JETP Letters》2021,113(8):542-546
JETP Letters - It is demonstrated that the PT-symmetric terahertz photoconductivity observed in heterostructures based on thick Hg1 – xCdxTe films in the topological phase is due to the... 相似文献
49.
The paper deals with approximations of a functionf of space Lp[0, 1] by rational functions in the metric of this same space (0n(f, p) of functionf of rational functions of degree no higher than n is evidence of the presence inf of derivatives and differentials of a definite order if differentiation is understood as differentiation in the metric of space Lq[0, 1], with 0
相似文献
50.