全文获取类型
收费全文 | 1231篇 |
免费 | 46篇 |
国内免费 | 5篇 |
专业分类
化学 | 974篇 |
晶体学 | 10篇 |
力学 | 6篇 |
数学 | 66篇 |
物理学 | 226篇 |
出版年
2023年 | 10篇 |
2022年 | 11篇 |
2021年 | 15篇 |
2020年 | 15篇 |
2019年 | 24篇 |
2018年 | 15篇 |
2017年 | 19篇 |
2016年 | 26篇 |
2015年 | 25篇 |
2014年 | 33篇 |
2013年 | 78篇 |
2012年 | 64篇 |
2011年 | 97篇 |
2010年 | 44篇 |
2009年 | 38篇 |
2008年 | 88篇 |
2007年 | 76篇 |
2006年 | 72篇 |
2005年 | 77篇 |
2004年 | 78篇 |
2003年 | 70篇 |
2002年 | 74篇 |
2001年 | 14篇 |
2000年 | 17篇 |
1999年 | 13篇 |
1998年 | 14篇 |
1997年 | 11篇 |
1996年 | 15篇 |
1995年 | 6篇 |
1994年 | 4篇 |
1993年 | 5篇 |
1991年 | 7篇 |
1990年 | 6篇 |
1989年 | 6篇 |
1988年 | 7篇 |
1986年 | 3篇 |
1985年 | 12篇 |
1984年 | 12篇 |
1982年 | 6篇 |
1981年 | 13篇 |
1980年 | 10篇 |
1979年 | 7篇 |
1978年 | 4篇 |
1977年 | 8篇 |
1976年 | 4篇 |
1975年 | 3篇 |
1974年 | 3篇 |
1973年 | 3篇 |
1964年 | 3篇 |
1961年 | 2篇 |
排序方式: 共有1282条查询结果,搜索用时 15 毫秒
951.
Molecular Recognition by a Short Partial Peptide of the Adrenergic Receptor: A Bottom‐Up Approach 下载免费PDF全文
Tsubasa Sekiguchi Masato Tamura Hikari Oba Dr. Pierre Çarçarbal Dr. Rolando Rafael Lozada‐Garcia Prof. Dr. Anne Zehnacker‐Rentien Dr. Gilles Grégoire Prof. Dr. Shun‐ichi Ishiuchi Prof.Dr. Masaaki Fujii 《Angewandte Chemie (International ed. in English)》2018,57(20):5626-5629
Receptor–neurotransmitter molecular recognition is key for neurotransmission. Although crystal structures of the receptors are known, the mechanism for recognition is not clear. Reported here is the ultraviolet (UV) and infrared (IR) spectra of complexes between a partial peptide (SIVSF), mimicking the binding motif of a catechol ring in the adrenergic receptor, and various ligands. The UV spectra show that two isomers coexist in the complex of SIVSF with properly recognized ligands, such as protonated adrenaline (adrenalineH+). From IR spectra, they are assigned to catechol‐ and amino‐bound structures. The catechol‐bound structure is not observed when the ligand is replaced by nonproper molecules, such as noradrenalineH+. The results suggest that SIVSF not only recognizes the catechol ring but can distinguish differences in the amine side chain. The method provides a new possibility for screening molecules as potential therapeutics for activating the receptor. 相似文献
952.
Inside Cover: Molecular Recognition by a Short Partial Peptide of the Adrenergic Receptor: A Bottom‐Up Approach (Angew. Chem. Int. Ed. 20/2018) 下载免费PDF全文
953.
Yoshinori Nakayama Yuzuru Sanemitsu Masato Mizutani Hirosuke Yoshioka 《Journal of heterocyclic chemistry》1981,18(3):631-632
A facile synthesis of 4,5-dihydro-1,2,4-triazin-3-(2H)one (2a) from 5-methylthio-1,2,4-triazin-3-(2H)one (1a) with sodium borohydride is described. The reaction provides a convenient method for its 6-substituted derivatives (2b-h). 相似文献
954.
Oka H Harada K Suzuki M Fujii K Iwaya M Ito Y Goto T Matsumoto H Ito Y 《Journal of chromatography. A》2003,989(2):249-255
Quinoline yellow (Color Index No. 47005) consists of multiple components that show a large difference in their partition coefficients (K), ranging from 0.03 to 3.3 in the solvent system tert.-butyl methyl ether (MTBE)-1-butanol-acetonitrile-aqueous 0.1 M trifluoroacetic acid (TFA). Consequently, it requires an excessively long elution time for the simultaneous separation of all components by the standard high-speed counter-current chromatography technique, which uses a constant flow-rate of the mobile phase. In order to overcome this problem, we increased the flow-rate of the mobile phase stepwise from 0.1 to 2.0 mL/min. Using this new procedure, six components (0.2-6.1 mg) were successfully isolated from 25 mg of a commercial quinoline yellow preparation in a single run using a two-phase solvent system composed of MTBE-1-butanol-acetonitrile-aqueous 0.1 M TFA (1:3:1:5, v/v). The purified components were analyzed by high-performance liquid chromatography, electrospray ionization mass spectrometry, and nuclear magnetic resonance spectroscopy. 相似文献
955.
956.
Summary Two new chromogenic crown reagents, 22-Kosh and 21-Kosh, have been synthesized by the condensation of Cryptand-22 and -21, respectively, with 2-hydroxy-5-nitrobenzyl bromide. Extraction of alkaline-earth metal ions with a dichloroethane solution of 22-Kosh or 21-Kosh has been investigated and their extraction coefficients have been evaluated. The relative ease of extraction is MgBa4 l·mole–1·cm–1 at 406 nm.
Part VI: M. Takagi, H. Nakamura, Y. Sanui, and K. Ueno, Analyt. Chim. Acta, in the press.
Presented at the 8th International Microchemical Symposium; Graz, August 25–30, 1980. 相似文献
Auf Kronenetherkomplexbindung basierende photometrische Reagenzien. VIIPhotometrische Bestimmung von Calcium in biologischem Material mit N,N-bis(2-hydroxy-5-nitrobenzyl)-1,10-diaza-4,7,13,16-tetraoxacyklooctadecan
Zusammenfassung Zwei neue chromogene Kronenetherreagenzien, 22-Kosh und 21-Kosh wurden durch Kondensation von Cryptand-22 bzw. -21 mit 2-Hydroxy-5-nitrobenzylbromid synthetisiert. Die Extraktion der Erdalkalimetallionen mit einer Dichlorethanlösung von 22-Kosh oder 21-Kosh wurde untersucht und ihre Extraktionskonstanten wurden bestimmt. Für die Leichtigkeit der Extrahierbarkeit mit den beiden Reagenzien ergibt sich folgende Reihenfolge: MgBa4 bei 406 nm.
Part VI: M. Takagi, H. Nakamura, Y. Sanui, and K. Ueno, Analyt. Chim. Acta, in the press.
Presented at the 8th International Microchemical Symposium; Graz, August 25–30, 1980. 相似文献
957.
Sclerosporin, the major sporogenic substance of , and its related metabolite, sclerosporal, were shown to have the plain structures, , and , respectively. by using a micro-amount of the samples, and co-occurring sclerosporene probably to have the structure . 相似文献
958.
Hiroyoshi Kamogawa Yasuto Todo Masato Nanasawa 《Journal of polymer science. Part A, Polymer chemistry》1981,19(10):2571-2579
Vinyl monomers bearing phenoxazine units, were synthesized: 2-vinyl-phenoxazine starting with phenoxazine in a five-step synthesis; 3-acrylamido- or 3-methacrylamido-phenoxazines with or without 10-PhCH2 or 10-Me-substituent starting with o-benzylideneaminophenol or o-anisidine via 3-aminophenoxazines; and 3-(p-styrenesulfonamido)phenoxazines with or without 10-PhCH2- or 10-Me-substituent, also via 3-aminophenoxazines. Polymerizations of these noval monomers proceeded smoothly, except those having no 10-substituent. Changes of the visible absorption spectrum of iodine in THF with addition of the polymers and oligomers thus prepared were considerable, with the appearance of new absorption peaks for polymers with 10-Me-substituent. 相似文献
959.
Vestergaard M Kerman K Saito M Nagatani N Takamura Y Tamiya E 《Journal of the American Chemical Society》2005,127(34):11892-11893
We present the first electrochemical detection, characterization, and kinetic study of the aggregation of Alzheimer's disease (AD) amyloid beta peptides (Abeta-40, Abeta-42) using three different voltammetric techniques at a glassy carbon electrode (GCE). This method is based on detecting changes in the oxidation signal of tyrosine (Tyr) residue. As the peptides aggregate, there are structure conformational changes, which affect the degree of exposure of Tyr to the molecular surface of the peptides. The results show significant differences in the aggregation process between the two peptides, and these correlate highly with established techniques. The method is rapid and label-free, and the principle can be universally applied to other protein aggregation studies related to diseases, such as Huntington's, Parkinson's, and Creutzfeldt Jacob (CJD). This method could also be explored in screening for the effectiveness of AD therapies. 相似文献
960.
We describe how the local equilibrium electronic structure in a large system can be determined by using the recursion method of Haydock. By applying this method to the polyacetylene molecule, the energies of each atomic site and the forces acting on each bond are estimated and the equilibrium structure near the end of polyacetylene is determined. It is found out that the degree of localization of π electrons and the bond length alternation become stronger near the end of the polyacetylene molecule. 相似文献