全文获取类型
收费全文 | 119篇 |
免费 | 5篇 |
专业分类
化学 | 120篇 |
物理学 | 4篇 |
出版年
2023年 | 1篇 |
2022年 | 1篇 |
2021年 | 3篇 |
2020年 | 1篇 |
2019年 | 3篇 |
2017年 | 2篇 |
2016年 | 2篇 |
2015年 | 1篇 |
2014年 | 3篇 |
2012年 | 3篇 |
2011年 | 5篇 |
2010年 | 2篇 |
2008年 | 7篇 |
2007年 | 4篇 |
2006年 | 9篇 |
2005年 | 9篇 |
2004年 | 6篇 |
2003年 | 5篇 |
2002年 | 10篇 |
2001年 | 5篇 |
1997年 | 6篇 |
1996年 | 3篇 |
1995年 | 2篇 |
1994年 | 3篇 |
1993年 | 3篇 |
1992年 | 1篇 |
1990年 | 5篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1984年 | 2篇 |
1982年 | 1篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1973年 | 1篇 |
排序方式: 共有124条查询结果,搜索用时 0 毫秒
121.
Zheng Q Bohling JC Peters TB Frisch AC Hampel F Gladysz JA 《Chemistry (Weinheim an der Bergstrasse, Germany)》2006,12(25):6486-6505
The reaction of trans-[PtCl(p-tol){P(p-tol)3}2] (PtCl) and H(C[triple chemical bond]C)2H (cat. CuI, HNEt2) gives PtC4H (82 %), which can be cross-coupled with excess HC[triple chemical bond]CSiEt3 (acetone, O2, CuCl/TMEDA; Hay conditions) to yield PtC6Si (77 %). The addition of nBu4N+F- in wet acetone gives PtC6H (84 %), and further addition of ClSiMe3 (F- scavenger) and excess HC[triple chemical bond]CSiEt3 (Hay conditions) yields PtC(8)Si (23 %). Similar cross-coupling reactions of PtCxH (generated in situ for x>6) and excess H(C[triple chemical bond]C)2SiEt3 give a) x=4, PtC8Si (29 %), PtC12Si (30 %), and PtC16Si (1 %); b) x=6, PtC10Si (59 %) and PtC14Si (7 %); c) x=8, PtC12Si (42 %); and d) x=10, PtC14Si (20 %). Hay homocoupling reactions of PtC4H, PtC6H, PtC8H, and PtC10H give PtC8Pt, PtC12Pt, PtC16Pt, and PtC20Pt (88-70 %), but PtC12H decomposes too rapidly. However, when PtC12Si and PtC14Si are subjected to Hay conditions, protodesilylation occurs in the presence of the oxidizing agent and PtC24Pt (36 %) and PtC28Pt (51 %) are isolated. Reactions of PtC6H and PtC10H with PtCl (CuI, HNEt2) give PtC6Pt (56 %) and PtC10Pt (84 %). The effect of the chain lengths in PtCxPt upon thermal stabilities (>200 degrees C for x< or =20), IR nu(C[triple chemical bond]C) patterns (progressively more bands), colors (yellow to orange to deep red), UV/Vis spectra (progressively red-shifted and more intense bands with epsilon>400,000 M(-1) cm(-1)), redox properties (progressively more difficult oxidations), and NMR spectra (many monotonic trends) are analyzed, including implications for the sp carbon allotrope carbyne. Whereas all other dodecaynes and tetradecaynes rapidly decompose at room temperature, PtC24Pt and PtC28Pt remain stable at >140 degrees C. Crystal structures of PtCxSi (x=6, 8, 10) and PtCxPt (x=6, 8, 10, 12) have been determined. 相似文献
122.
Dr. Dante A. Castillo Molina Taveechai Wititsuwannakul Dr. Frank Hampel Prof. Dr. Michael B. Hall Prof. Dr. John A. Gladysz 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(53):13399-13417
Reactions of Li+ [(η5-C5H5)Re(NO)(PPh3)]− with 2- and 4-chloroquinoline or 1-chloroisoquinoline give the corresponding σ quinolinyl and isoquinolinyl complexes 3 , 6 , and 8 . With 3 and 8 there is further protonation to yield HCl adducts, but additions of KH give the free bases. Treatment of 3 with HBF4⋅OEt2 or H(OEt2)2+ BArf− gives the quinolinium salts [(η5-C5H5)Re(NO)(PPh3)(C(NH)C(CH)4C (CH)(CH))]+ X− ( 3-H + X−; X−=BF4−/BArf−, 94–98 %). Addition of CF3SO3CH3 to 3 , 6 , or 8 affords the corresponding N-methyl quinolinium salts. In the case of [(η5-C5H5)Re(NO)(PPh3)(C(NCH3)C(CH)4C (CH)(CH))]+ CF3SO3− ( 3-CH3 + CF3SO3−), addition of CH3Li gives the dihydroquinolinium complex (SReRC,RReSC)-[(η5-C5H5)Re(NO)(PPh3)(C(NCH3)C(CH)4C (CHCH3)(CH2))]+ CF3SO3− ((SReRC,RReSC)- 5 + CF3SO3−, 76 %) in diastereomerically pure form. Crystal structures of 3-H + BArf−, 3-CH3 + CF3SO3−, (SReRC, RReSC)- 5 + Cl−, and 6-CH3 + CF3SO3− show that the quinolinium ligands adopt Re⋅⋅⋅ C conformations that maximize overlap of their acceptor orbitals with the rhenium fragment HOMO, minimize steric interactions with the bulky PPh3 ligand, and promote various π interactions. NMR experiments establish the Brønsted basicity order 3 > 8 > 6 , with Ka(BH+) values >10 orders of magnitude greater than the parent heterocycles, although they remain less active nucleophilic catalysts in the reactions tested. DFT calculations provide additional insights regarding Re⋅⋅⋅ C bonding and conformations, basicities, and the stereochemistry of CH3Li addition. 相似文献
123.
Irene Lim Eric Yu Lin Joseph Garcia Shang Jia Robert E. Sommerhalter Subrata K. Ghosh John A. Gladysz Ellen M. Sletten 《Angewandte Chemie (International ed. in English)》2023,62(6):e202215200
Developing chemical tools to detect and influence biological processes is a cornerstone of chemical biology. Here we combine two tools which rely on orthogonality– perfluorocarbons and multiplexed shortwave infrared (SWIR) fluorescence imaging– to visualize nanoemulsions in real time in living mice. Drawing inspiration from fluorous and SWIR fluorophore development, we prepared two SWIR-emissive, fluorous-soluble chromenylium polymethine dyes. These are the most red-shifted fluorous fluorophores– “fluorofluorophores”—to date. After characterizing the dyes, their utility was demonstrated by tracking perfluorocarbon nanoemulsion biodistribution in vivo. Using an excitation-multiplexed approach to image two variables simultaneously, we gained insight into the importance of size and surfactant identity on biodistribution. 相似文献
124.