全文获取类型
收费全文 | 435篇 |
免费 | 32篇 |
专业分类
化学 | 353篇 |
晶体学 | 5篇 |
力学 | 11篇 |
数学 | 16篇 |
物理学 | 82篇 |
出版年
2023年 | 4篇 |
2022年 | 13篇 |
2021年 | 13篇 |
2020年 | 16篇 |
2019年 | 15篇 |
2018年 | 15篇 |
2017年 | 10篇 |
2016年 | 16篇 |
2015年 | 18篇 |
2014年 | 22篇 |
2013年 | 20篇 |
2012年 | 30篇 |
2011年 | 37篇 |
2010年 | 29篇 |
2009年 | 28篇 |
2008年 | 30篇 |
2007年 | 24篇 |
2006年 | 26篇 |
2005年 | 16篇 |
2004年 | 21篇 |
2003年 | 11篇 |
2002年 | 8篇 |
2001年 | 3篇 |
2000年 | 4篇 |
1999年 | 2篇 |
1998年 | 3篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1989年 | 1篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1978年 | 5篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 2篇 |
1973年 | 2篇 |
1972年 | 1篇 |
排序方式: 共有467条查询结果,搜索用时 15 毫秒
41.
Treatment of 6-amino-5-arylazo-1,3-dimethyluracils with ethyl propiolate gave the corresponding Michael-type adducts, 5-arylazo-1,3-dimethyl-6-ethoxycarbonylvinylaminouracils, which on treatment with a mixture of hydrochloric acid and acetic acid caused the acid-catalyzed rearrangement accompanied with rearrangement to give rise to the corresponding 8-anilinomethyltheophylline derivatives. In the case that the arylazo group possesses an electron-releasing substituent such as methoxy, the reaction proceeded in a different way to afford 1,2-bis(theophyllin-8-yl)ethane. The presumable reaction mechanisms for the above purine syntheses were proposed. 相似文献
42.
Fumio Yoneda Ryosuke Koga Sadao Nishigaki Shinobu Fukazawa 《Journal of heterocyclic chemistry》1982,19(4):949-951
Treatment of 6-amino-1,3-dimethyl-5-nitrosouracil (Ia) with dimethyl acetylenedicarboxylate (DMAD) in dimethylformamide (DMF) afforded 6,7-bis(dimethoxycarbonyl)-1,3-dimethyllumazine (II). Similarly, the reaction of 6-amino-1,3-dimethyl-5-phenylazouracil with DMAD gave also II. Hydrolysis of II with hydrochloric acid gave 1,3-dimethyllumazine-6-carboxylic acid (III). III was chlorinated with thionyl chloride and then aminated with ethanolic ammonia to give rise to 6-carbamoyl-1,3-dimethyllumazine (V). V was alternatively synthesized by the treatment of Ia with propiolamide in DMF. 相似文献
43.
Prof. Dr. Takako Muraoka Ryosuke Ishizeki Shun Tanabe Dr. Keiji Ueno 《欧洲无机化学杂志》2023,26(18):e202300124
Silanethione compounds, R2Si=S, have been recognized as highly reactive species. One reliable way to stabilize silanethione is its coordination to transition metal fragments to convert silanethione-coordinated transition metal complexes. Herein, we report the synthesis, structure, and reactivity of a second cationic silanethione tungsten complex [Cp*(OC)3W{S=SiR2(py)}]TFPB (R=Me ( 5 a ), Ph ( 5 b ), Cp*: η5-C5Me5, py: pyridine, and TFPB−: [B{3,5-(CF3)2C6H3}4]−). Complex 5 was obtained by H− abstraction from the Si atom in the corresponding silylsulfanyl complex Cp*(OC)3W(SSiR2H) ( 4 ) with Ph3CTFPB, followed by the addition of pyridine. The reaction of 5 with PhNCS and PMe3 produced [Cp*(OC)3W{SSiR2N(Ph)C(PMe3)2}]TFPB (R=Me ( 6 a ), Ph ( 6 b )) via the elimination of pyridine and the addition of the 1,3-dipolar species PhNC(PMe3)2 ( A ) to the Si atom. 相似文献
44.
Karataev P Araki S Hamatsu R Hayano H Muto T Naumenko G Potylitsyn A Terunuma N Urakawa J 《Physical review letters》2004,93(24):244802
An experiment on the investigation of optical diffraction radiation (ODR) from a slit target as a possible tool for noninvasive electron beam-size diagnostics has been performed at the KEK accelerator test facility. The experimental setup has been installed at the diagnostics section of the extraction line. We have performed the first incoherent ODR observation from a slit target. The measured angular distributions are in reasonable agreement with the theoretical expectation. The beam-size effect onto the ODR angular pattern has been observed. Moreover, the sensitivity to the beam size as small as 14 microm has been achieved. 相似文献
45.
46.
Ryosuke Sakae Dr. Koji Hirano Prof. Dr. Tetsuya Satoh Prof. Dr. Masahiro Miura 《Angewandte Chemie (International ed. in English)》2015,54(2):613-617
A copper‐catalyzed aminoboration of bicyclic alkenes, including oxa‐ and azabenzonorbornadienes, has been developed. With this method, amine and boron moieties are simultaneously introduced at an olefin with exo selectivity. Subsequent stereospecific transformations of the boryl group can provide oxygen‐ and nitrogen‐rich cyclic molecules with motifs that may be found in natural products or pharmaceutically active compounds. Moreover, a catalytic asymmetric variant of this transformation was realized by using a copper complex with a chiral bisphosphine ligand, namely (R,R)‐Ph‐BPE. 相似文献
47.
Shunsuke Murai Ryosuke Hattori Tomohiko Matoba Koji Fujita Katsuhisa Tanaka 《Journal of Non》2011,357(11-13):2259-2263
Wavelength-selective enhancement of optical birefringence has been observed in a tellurite glass containing silver nanoparticles (Ag NPs) induced via thermal poling. The birefringence appears as an optical rotation of linearly polarized light; a large optical rotation is observed at around the wavelength of localized surface plasmon resonance (LSPR) of Ag NPs. The optic axis is oriented along the electric field applied during the thermal poling, suggesting that birefringence induced in the glass matrix through the thermal poling is drastically enhanced by the NPs at around the LSPR. Because of the birefringence of the matrix, the wavelength of LSPR shifts depending on the polarization state of the incident light, which in turn induces the polarization dependence of the real part of the refractive index via the Kramers–Kronig relation. 相似文献
48.
Dr. Tatsuya Takimoto Prof. Hideaki Sasaki Prof. Hirohito Tsue Dr. Hiroki Takahashi Prof. Alexander D. MacKerell Jr. Ayumi Nakamura Katsuya Nakano Eori Okazaki Tatsuki Betsuyaku Ryosuke Tachibana Dr. Kazuhito Hioki Dr. Ozge Yoluk Dr. Sunhwan Jo 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(5):1648-1654
A simple approach to the synthesis of heterocyclophane consisting of two 4,4’-bithiazoles has been developed in mild conditions. The heterocyclophane with two short chains was conveniently prepared by Hantzsch thiazoles synthesis using the reaction of 3-tert-butoxycarbonyl-3-azapentanethiocarboxamide with 1,4-dibromobutane-2,3-dione in methanol under reflux for only 15 min. Amino groups at the linkers of this heterocyclophane can be functionalized to give acylated and carbamate derivatives. Their properties as protein kinase inhibitors were investigated, and one of the heterocyclophanes exhibited specific anti-activity for c-mesenchymal epithelial transition factor (IC50=603 nm ), among seven types of protein kinases investigated. The computational site identification by ligand competitive saturation method was used to determine why the one heterocyclophane exhibited strong anti-activity for c-mesenchymal epithelial transition factor. 相似文献
49.
50.
Hideki Misaka Eisuke Tamura Kosuke Makiguchi Kensuke Kamoshida Ryosuke Sakai Toshifumi Satoh Toyoji Kakuchi 《Journal of polymer science. Part A, Polymer chemistry》2012,50(10):1941-1952
For the living ring‐opening polymerization (ROP) of epoxy monomers, the catalytic activity of organic superbases, tert‐butylimino‐tris(dimethylamino)phosphorane, 1‐tert‐butyl‐2,2,4,4,4‐pentakis(dimethylamino)‐2Λ5,4Λ5‐catenadi(phosphazene), 2,8,9‐triisobutyl‐2,5,8,9‐tetraaza‐1‐phosphabicyclo[3.3.3]undecane, and 1‐tert‐butyl‐4,4,4‐tris(dimethylamino)‐2,2‐bis[tris(dimethylamino)phosphoranylidenamino]‐2Λ5,4Λ5‐catenadi(phosphazene) (t‐Bu‐P4), was confirmed. Among these superbases, only t‐Bu‐P4 showed catalytic activity for the ROP of 1,2‐butylene oxide (BO) to afford poly(1,2‐butylene oxide) (PBO) with predicted molecular weight and narrow molecular weight distribution. The results of the kinetic, post‐polymerization experiments, and MALDI‐TOF MS measurement revealed that the t‐Bu‐P4‐catalyzed ROP of BO proceeded in a living manner in which the alcohol acted as the initiator. This alcohol/t‐Bu‐P4 system was applicable to the glycidol derivatives, such as benzyl glycidyl ether (BnGE) and t‐butyl glycidyl ether, to afford well‐defined protected polyglycidols. The α‐functionalized polyethers could be obtained using different functionalized initiators, such as 4‐vinylbenzyl alcohol, 5‐hexen‐1‐ol, and 6‐azide‐1‐hexanol. In addition, the well‐defined cyclic‐PBO and PBnGE were successfully synthesized using the combination of t‐Bu‐P4‐catalyzed ROP and click cyclization. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012 相似文献