全文获取类型
收费全文 | 159篇 |
免费 | 1篇 |
专业分类
化学 | 130篇 |
晶体学 | 4篇 |
力学 | 4篇 |
数学 | 14篇 |
物理学 | 8篇 |
出版年
2021年 | 2篇 |
2020年 | 5篇 |
2019年 | 3篇 |
2018年 | 6篇 |
2017年 | 5篇 |
2016年 | 7篇 |
2015年 | 6篇 |
2014年 | 5篇 |
2013年 | 8篇 |
2012年 | 13篇 |
2011年 | 14篇 |
2010年 | 8篇 |
2009年 | 9篇 |
2008年 | 15篇 |
2007年 | 8篇 |
2006年 | 14篇 |
2005年 | 6篇 |
2004年 | 5篇 |
2003年 | 1篇 |
2002年 | 2篇 |
2001年 | 2篇 |
2000年 | 1篇 |
1995年 | 1篇 |
1991年 | 1篇 |
1988年 | 1篇 |
1986年 | 1篇 |
1981年 | 1篇 |
1979年 | 1篇 |
1977年 | 1篇 |
1976年 | 3篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1972年 | 1篇 |
排序方式: 共有160条查询结果,搜索用时 140 毫秒
1.
2.
V. P. Rybalkin E. N. Shepelenko V. V. Tkachev G. V. Shilov S. K. Balenko A. V. Tsukanov L. L. Popova A. D. Dubonosov S. M. Aldoshin V. A. Bren’ V. I. Minkin 《Russian Chemical Bulletin》2006,55(1):101-105
New photochromic fulgide, viz., 4-{1-[2-(anthracen-9-yl)-5-methyloxazol-4-yl]ethylidene}-3-isopropylidenetetrahydrofuran-2,5-dione, with fluorescent properties
was synthesized. Studies by electronic, IR, and 1H NMR spectroscopy and X-ray diffraction demonstrated that this fulgide exists in the Z form. Light irradiation of its solutions at a wavelength of 365 nm causes Z/E isomerization giving rise to the thermally stable cyclic form. The latter is transformed into the starting E isomer under light irradiation at λ = 436 nm.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 97–101, January, 2006. 相似文献
3.
NMR spectroscopy has become a vital tool for studies of protein conformational changes and dynamics. Oxidized Fe(III)cytochromes c are a particularly attractive target for NMR analysis because their paramagnetism (S = (1)/(2)) leads to high (1)H chemical shift dispersion, even for unfolded or otherwise disordered states. In addition, analysis of shifts induced by the hyperfine interaction reveals details of the structure of the heme and its ligands for native and nonnative protein conformational states. The use of NMR spectroscopy to investigate the folding and dynamics of paramagnetic cytochromes c is reviewed here. Studies of nonnative conformations formed by denaturation and by anomalous in vivo maturation (heme attachment) are facilitated by the paramagnetic, low-spin nature of native and nonnative forms of cytochromes c. Investigation of the dynamics of folded cytochromes c also are aided by their paramagnetism. As an example of this analysis, the expression in Escherichia coli of cytochrome c(552) from Nitrosomonas europaea is reported here, along with analysis of its unusual heme hyperfine shifts. The results are suggestive of heme axial methionine fluxion in N. europaea ferricytochrome c(552). The application of NMR spectroscopy to investigate paramagnetic cytochrome c folding and dynamics has advanced our understanding of the structure and dynamics of both native and nonnative states of heme proteins. 相似文献
4.
Jurij V. Brenčič Boris Čeh Ivan Leban 《Monatshefte für Chemie / Chemical Monthly》1981,112(12):1359-1368
Trans-[Cr(NH3)4F2]I·H2O (A) has monoclinic P2l/m (No. 11) space group witha=5.033 (3),b=16.333 (10),c=5.539 (3) Å and =98.47 (3)°,Z=2.Cis-[Cr(NH3)4F2]ClO4 (B) has tetragonal space group I4lmd (No. 109) witha=7.417 (1),c=16.610 (2) Å,Z=4. Cr–F and Cr–N bonding distances are 1.894 (3); 2.087 and 2.083 (5) Å for A and 1.887 (6); 2.062 (5) and 2.051 (7) Å for B. Octahedral angles within the cations are close to 90° for both compounds. Cr–N bondtrans to Cr–F bond in thecis compound is shorter. Structures were refined toR
2 values of 0.072 (A) and 0.058 (B).Trans-[Cr(NH3)4F2]I·H2O has weak N–H–F hydrogen bonds between the cations. None such interactions were found incis-[Cr(NH3)4F2]ClO4.
Fluorhältige Komplexe des Cr(III), 2. Mitt.: Kristall- und Molekülstruktur von trans-[Cr(NH3)4F2]I·H2O und cis-[Cr(NH3)4F2]ClO4
Zusammenfassung Trans-[Cr(NH3)4F2]I·H2O (A) kristallisiert in der Raumgruppe P2l/m (No. 11) mitZ=2 unda=5,033 (3),b=16,333 (10),c=5,539 (3) Å und =98,47 (3)°.Cis-[Cr(NH3)4F2]ClO4 (B) kristallisiert in der Raumgruppe I4lmd (No. 109) mitZ=4,a=7,417 (1) undc=16,610 (2) Å. Die Cr–F- und Cr–N-Abstände sind 1,894 (3); 2,087 (6), 2,083 (5) Å für A und 1,887 (6); 2,062 (5), 2,051 (7) Å für B. Die octaedrischen Bindungswinkel innerhalb der Kationen weichen nicht viel von 90° ab. Der Cr–N-Abstand intrans-Position der Cr–F-Bindung ist kürzer. Die Strukturen wurden bis zu GütefaktorenR 2 0,072 (A) und 0,058 (B) verfeinert. Bei der Verbindung A wurden schwache N–H ... F-Wasserstoff-Bindungen zwischen verschiedenen Kationen beobachtet, während bei der Verbindung B keine Wasserstoff-Bindungen vorhanden sind.相似文献
5.
A. D. Dubonosov V. P. Rybalkin Ya. Yu. Vorob’eva V. A. Bren’ V. I. Minkin S. M. Aldoshin V. V. Tkachev A. V. Tsukanov 《Russian Chemical Bulletin》2004,53(10):2248-2252
It was shown by electron absorption spectroscopy and X-ray diffraction analysis that steric strains in photochromic 2-(N-acyl-N-arylaminomethylene) benzo[b]thiophen-3(2H)-one molecules ortho-substituted in the N-phenyl ring increase the quantum yield of the N→O photoinduced rearrangement in accord with an increase in the steric constant of the ortho-substituent.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2151–2155, October, 2004. 相似文献
6.
7.
We apply the recently improved version of the 0–1 test for chaos to real experimental time series of laser droplet generation
process. In particular two marginal regimes of dripping are considered: spontaneous and forced dripping. The outcomes of the
test reveal that both spontaneous and forced dripping time series can be characterized as chaotic, which coincides with the
previous analysis based on nonlinear time series analysis. 相似文献
8.
V. I. Minkin A. D. Dubonosov V. A. Bren’ O. G. Nikolaeva A. V. Tsukanov O. N. Burov A. Yu. Fedyanina 《Russian Journal of Organic Chemistry》2013,49(3):374-378
Schiff bases were synthesized from 3-hydroxy-6-oxo-6H-benzo[c]chromene-4-carbaldehyde, 5-hydroxy-4,7-dimethyl-2-oxo-2H-chromene-6-carbaldehyde, 6,7-dihydroxy-4-methyl-2-oxo-2H-chromene-8-carbaldehyde, 5,7-dihydroxy-4-methyl-2-oxo-2H-chromene-6,8-dicarbaldehyde, and 5-hydroxy-4,7-dimethyl-2-oxo-2H-chromene-6,8-dicarbaldehyde and (15N)aniline or aminobenzo-15-crown-5 (2,3,5,6,8,9,11,12-octahydrobenzo[b][1,4,7,10,13]pentaoxacyclopentadecin-15-amine), and tautomeric equilibrium between the hydroxy enimino and keto enamino forms of the 4- and 8-iminomethyl derivatives in solution was revealed by 1H NMR and electronic spectroscopy. Addition of alkaline earth cations to their solutions in acetonitrile displaced the tautomeric equilibrium toward the hydroxy enimino structure due to complex formation with the crown ether fragment. 相似文献
9.
SARS-CoV-2, or severe acute respiratory syndrome coronavirus 2, represents a new strain of Coronaviridae. In the closing 2019 to early 2020 months, the virus caused a global pandemic of COVID-19 disease. We performed a virtual screening study in order to identify potential inhibitors of the SARS-CoV-2 main viral protease (3CLpro or Mpro). For this purpose, we developed a novel approach using ensemble docking high-throughput virtual screening directly coupled with subsequent Linear Interaction Energy (LIE) calculations to maximize the conformational space sampling and to assess the binding affinity of identified inhibitors. A large database of small commercial compounds was prepared, and top-scoring hits were identified with two compounds singled out, namely 1-[(R)-2-(1,3-benzimidazol-2-yl)-1-pyrrolidinyl]-2-(4-methyl-1,4-diazepan-1-yl)-1-ethanone and [({(S)-1-[(1H-indol-2-yl)methyl]-3-pyrrolidinyl}methyl)amino](5-methyl-2H-pyrazol-3-yl)formaldehyde. Moreover, we obtained a favorable binding free energy of the identified compounds, and using contact analysis we confirmed their stable binding modes in the 3CLpro active site. These compounds will facilitate further 3CLpro inhibitor design. 相似文献
10.