全文获取类型
收费全文 | 233篇 |
免费 | 6篇 |
国内免费 | 32篇 |
专业分类
化学 | 243篇 |
物理学 | 28篇 |
出版年
2022年 | 1篇 |
2021年 | 1篇 |
2020年 | 1篇 |
2019年 | 4篇 |
2018年 | 4篇 |
2017年 | 10篇 |
2016年 | 4篇 |
2015年 | 7篇 |
2014年 | 9篇 |
2013年 | 19篇 |
2012年 | 17篇 |
2011年 | 12篇 |
2010年 | 9篇 |
2009年 | 19篇 |
2008年 | 19篇 |
2007年 | 15篇 |
2006年 | 15篇 |
2005年 | 15篇 |
2004年 | 17篇 |
2003年 | 9篇 |
2002年 | 8篇 |
2001年 | 9篇 |
2000年 | 6篇 |
1999年 | 6篇 |
1998年 | 4篇 |
1997年 | 4篇 |
1996年 | 6篇 |
1995年 | 5篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1992年 | 6篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1988年 | 1篇 |
1984年 | 1篇 |
1980年 | 1篇 |
排序方式: 共有271条查询结果,搜索用时 15 毫秒
51.
Ryo Hirata Ayame Torii Kenichi Kawano Shiroh Futaki Ayumi Imayoshi Kazunori Tsubaki 《Tetrahedron》2018,74(27):3608-3615
Fluorescent dyes possessing a variety of arylacetylenes at the 9-position of a xanthene skeleton were synthesized and their optical properties were investigated. The π system effectively expanded over the xanthene skeleton and the aryl group through the triple bond. Starting from the emission wavelength (λem) of 9-methyl xanthene 20 in basic DMSO solution at 536?nm, the emission wavelengths gradually shifted to the red region for methylacetylene 17 (λem?=?600?nm), phenylacetylene 5 (λem?=?636?nm), and p-CF3-phenylacetylene 11 (λem?=?660?nm). On the basis of these data, we estimated the substituent effects for the red shift on the emission wavelength and rationally explained the results by DFT calculations. Furthermore, potential applicability of these fluorescent dyes to cell staining was exemplified. 相似文献
52.
G. Kh. Khisamutdinov T. A. Mratkhuzina R. M. Gabdullin I. Sh. Abdrakhmanov S. P. Smirnov O. A. Rakitin T. I. Godovikova L. I. Khmel'nitskii 《Russian Chemical Bulletin》1995,44(8):1499-1500
4,7-Diaminopyridazino[4,5-c]furoxan was synthesized by intramolecular cyclization of 3-cyanofuroxan-4-carbamidrazone obtained from 3,4-dicyanofuroxan and hydrazine.Deceased.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1559–1560, August, 1995. 相似文献
53.
Sasaki M Hayashi J Fujii M Koizumi K Fujita H Kobayashi M Kawakubo Y Ito A 《Journal of photochemistry and photobiology. B, Biology》2001,60(2-3):120-128
We propose a model of the intracellular delivery process in which fluorescein-labeled natural oligonucleotides (F-DNA) are transferred into the nuclei of cultured human keratinocytes. By encapsulation in neutral multilamellar lecithin liposomes, the F-DNA appeared to be protected against intracellular interactions with cellular materials and nuclease attacks in the cytoplasm during the process. The intracellular behavior of F-DNA and fluorescent phospholipid-labeled liposomes was observed by means of fluorescence analysis. Results showed that: F-DNA encapsulated in neutral multilamellar liposomes reached the cellular nuclei more efficiently than either free F-DNA, or F-DNA in unilamellar liposomes; the liposomal membranes appeared to be left in the cytoplasm. The reaction of F-DNA with complementary DNA was suggested by a rapid quenching of the fluorescence in the nucleus. In addition, the fluorescence decrease was evidently suppressed in the cytoplasm, indicating a protective effect of the neutral multilamellar liposomes against the interaction of F-DNA with cytoplasmic materials. The application of these findings to ‘photo’-antisense studies has been discussed, where suppression of a gene expression is attempted by using oligonucleotide-attached fluorescein with the aid of a photo-induced covalent binding property. 相似文献
54.
Enrique J. Baran Evelina G. Ferrer Maria C. Apella 《Monatshefte für Chemie / Chemical Monthly》1991,122(1-2):21-26
Summary Electronic and vibrational spectra of bis(imidazol)copper(II)diacetate were investigated in order to obtain a wider insight into the structural properties of this interesting complex compound, which presents high cytotoxic activity. Electronic transitions were investigated by reflectance measurements of the solid and by absorption, using aqueous and methanolic solutions. IR spectra could be interpreted on the basis of the characteristic ligand vibrations. Some information could also be obtained for the Cu-N and Cu-O vibrations. For comparative purposes, the IR spectrum of Cu(imidazol)4I2 was also recorded and analyzed. 相似文献
55.
56.
N. V. Uzenkova N. I. Petrenko M. M. Shakirov E. E. Shul'ts G. A. Tolstikov 《Chemistry of Natural Compounds》2005,41(6):692-700
New derivatives of betulin and betulinic acid containing various amines on C-30 that are of interest as potentially biologically
active agents were prepared.
__________
Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 571–577, November–December, 2005. 相似文献
57.
溴酸钾氧化荧光素动力学荧光法测定痕量亚硝酸根 总被引:27,自引:8,他引:27
基于稀硫酸介质中,亚硝酸根催化溴酸钾氧化荧光素,建立了动力学荧光法测定痕量亚硝酸根的新方法。本方法具有高灵敏度和高选择性,测定亚硝酸根的线性范围为2~80ng/ml,可用于直接测定水样中亚硝酸根。 相似文献
58.
59.
近年来,我们以荧光素为母体合成了一系列的衍生物,药理试验证实其中许多种对肿瘤细胞有明显的杀伤和抑制增殖作用。本文用非线性映照(NLM)模式识别技术研究其活性分类,得到分类清晰的映照图,确定了该类衍生物抗ECa 109细胞的主要结构因素,为指导合成新化合物建立了预报模型。 1 结构参数选择与非线性映照 相似文献
60.
提出了以二醋酸纤维为吸附剂吸附石油气基质金属切割气中的添加剂,用超临界流体抽提吸附质,用气相色谱衣气相色谱-质谱联用分析的方法,研究了石油基质金属切割气的组成,模拟配制金属切割气样品经实际验证切割性能优于乙炔气。 相似文献