全文获取类型
收费全文 | 83篇 |
免费 | 5篇 |
专业分类
化学 | 73篇 |
力学 | 1篇 |
数学 | 8篇 |
物理学 | 6篇 |
出版年
2023年 | 1篇 |
2022年 | 3篇 |
2021年 | 4篇 |
2020年 | 4篇 |
2019年 | 5篇 |
2018年 | 1篇 |
2017年 | 2篇 |
2016年 | 3篇 |
2015年 | 5篇 |
2014年 | 1篇 |
2013年 | 5篇 |
2012年 | 6篇 |
2011年 | 9篇 |
2010年 | 1篇 |
2009年 | 3篇 |
2008年 | 2篇 |
2007年 | 4篇 |
2006年 | 7篇 |
2005年 | 3篇 |
2004年 | 4篇 |
2003年 | 1篇 |
2002年 | 2篇 |
2001年 | 3篇 |
1999年 | 1篇 |
1996年 | 1篇 |
1988年 | 2篇 |
1983年 | 1篇 |
1979年 | 1篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1932年 | 1篇 |
排序方式: 共有88条查询结果,搜索用时 15 毫秒
1.
2.
3.
Constanze Keck Dr. Jennifer Hahn Divanshu Gupta Prof. Dr. Holger F. Bettinger 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(5):e202103614
The boron-nitrogen analogue of ortho-benzyne, 1,2-azaborinine, is a reactive intermediate that features a formal boron-nitrogen triple bond. We here show by combining experimental and computational techniques that the Lewis acidity of the boron center of dibenzo[c,e][1,2]azaborinine allows interaction with the silicon containing single bonds Si−E through the silicon bonding partner E (E=F, Cl, OR, H). The binding to boron activates the Si−E bonds for subsequent insertion reaction. This shows that the BN-aryne is a ferocious species that even can activate and insert into the very strong Si−F bond. 相似文献
4.
Dr. Peter Thumbs M. Sc. Timm T. Ensfelder M. Sc. Markus Hillmeier Dr. Mirko Wagner M. Sc. Matthias Heiss M. Sc. Constanze Scheel M. Sc. Alexander Schön Dr. Markus Müller Prof. Dr. Stylianos Michalakis Dr. Stefanie Kellner Prof. Dr. Thomas Carell 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(30):12451-12455
5.
Thomas Harmening Constanze M. Fehse Rainer Pöttgen 《Journal of solid state chemistry》2011,184(12):3303-3309
The silicides ScTSi (T=Fe, Co, Ni, Cu, Ru, Rh, Pd, Ir, Pt) were synthesized by arc-melting and characterized by X-ray powder diffraction. The structures of ScCoSi, ScRuSi, ScPdSi, and ScIrSi were refined from single crystal diffractometer data. These silicides crystallize with the TiNiSi type, space group Pnma. No systematic influences of the 45Sc isotropic magnetic shift and nuclear electric quadrupolar coupling parameters on various structural distortion parameters calculated from the crystal structure data can be detected. 45Sc MAS-NMR data suggest systematic trends in the local electronic structure probed by the scandium atoms: both the electric field gradients and the isotropic magnetic shifts relative to a 0.2 M aqueous Sc(NO3)3 solution decrease with increasing valence electron concentration and within each T group the isotropic magnetic shift decreases monotonically with increasing atomic number. The 45Sc nuclear electric quadrupolar coupling constants are generally well reproduced by quantum mechanical electric field gradient calculations using the WIEN2k code. 相似文献
6.
We define two model structures on the category of bicomplexes concentrated in the right half plane. The first model structure has weak equivalences detected by the totalisation functor. The second model structure's weak equivalences are detected by the -term of the spectral sequence associated to the filtration of the total complex by the horizontal degree. We then extend this result to twisted complexes. 相似文献
7.
For a unitary operator U in a Hilbert space H the family of its unitary perturbations by rank one operators with fixed range is parametrized by a complex parameter γ, ?γ? = 1. Namely, all such unitary perturbations are operators Uγ:= U + (γ ? 1)( ·, b1)Hb, where b ∈ H, ∥b∥ = 1, b1 = U?1b, ?γ? = 1. For ?γ? < 1, the operators Uγ are contractions with one-dimensional defects. 相似文献
8.
Detonation waves in trinitrotoluene 总被引:1,自引:0,他引:1
Fabry-Perot, ORVIS, and VISAR laser interferometry are used to obtain nanosecond time resolved particle velocity histories
of the free surfaces of copper and tantalum discs accelerated by detonating trinitrotoluene (TNT) charges and of the interfaces
between TNT detonation products and lithium fluoride crystals. TNT detonation reaction zone profiles are measured for self-sustaining
detonation and piston supported overdriven (supracompressed) waves. The experimental records are compared to particle velocity
histories calculated using very finely zoned meshes of the exact dimensions with the DYNA2D hydrodynamic code. The Ignition
and Growth reactive flow model, which is based on the Zeldovich-von Neumann-D?ring (ZND) theory of detonation, yields excellent
agreement with the experimental records for TNT using an unreacted von Neumann spike pressure of 25 GPa, a reaction rate law
which releases 90% of the chemical energy within 80 ns and the remaining 10% over an additional 200 ns, and a reaction product
equation of state fit to cylinder test data assuming a Chapman-Jouguet pressure of 19 GPa. The late time energy release is
attributed to diffusion controlled solid carbon particle formation.
Received 26 July 1997 / Accepted 29 December 1997 相似文献
9.
Constanze Hägele Dr. Eugen Wuckert Sabine Laschat Prof. Dr. Frank Giesselmann Prof. Dr. 《Chemphyschem》2009,10(8):1291-1298
Rather uncommon but pronounced odd–even effects in the clearing temperatures of liquid crystals are found for three new homologous series of discotic tetraphenylenes (see figure). Detailed similarities to the well‐known odd‐even effects in calmitic mesogens point towards a more general understanding of odd‐even effects in liquid crystals.
10.
Delley RJ Bandyopadhyay S Fox MA Schliehe C Hodgson DR Hollfelder F Kirby AJ O'Donoghue AC 《Organic & biomolecular chemistry》2012,10(3):590-596
The rate constants for exchange of hydrogen for deuterium at the α-CH(2) positions of 8-(N,N-dimethylaminonaphthalen-1-yl)acetic acid tert-butyl ester 1 and naphthalen-1-ylacetic acid tert-butyl ester 2 have been determined in potassium deuteroxide solutions in 1 : 1 D(2)O : CD(3)CN, in order to quantify the effect of the neighbouring peri-dimethylamino substituent on α-deprotonation. Intramolecular general base catalysis by the (weakly basic) neighbouring group was not detected. Second-order rate constants, k(DO), for the deuterium exchange reactions of esters 1 and 2 have been determined as 1.35 × 10(-4) M(-1) s(-1) and 3.95 × 10(-3) M(-1) s(-1), respectively. The unexpected 29-fold decrease in the k(DO) value upon the introduction of a peri-dimethylamino group is attributed to an unfavourable steric and/or electronic substituent effect on intermolecular deprotonation by deuteroxide ion. From the experimental k(DO) values, carbon acid pK(a) values of 26.8 and 23.1 have been calculated for esters 1 and 2. 相似文献