全文获取类型
收费全文 | 393篇 |
免费 | 29篇 |
专业分类
化学 | 320篇 |
晶体学 | 4篇 |
力学 | 18篇 |
数学 | 18篇 |
物理学 | 62篇 |
出版年
2024年 | 1篇 |
2023年 | 7篇 |
2022年 | 7篇 |
2021年 | 7篇 |
2020年 | 5篇 |
2019年 | 15篇 |
2018年 | 6篇 |
2017年 | 3篇 |
2016年 | 24篇 |
2015年 | 7篇 |
2014年 | 22篇 |
2013年 | 29篇 |
2012年 | 34篇 |
2011年 | 38篇 |
2010年 | 22篇 |
2009年 | 23篇 |
2008年 | 24篇 |
2007年 | 16篇 |
2006年 | 28篇 |
2005年 | 22篇 |
2004年 | 17篇 |
2003年 | 8篇 |
2002年 | 5篇 |
2001年 | 5篇 |
1998年 | 1篇 |
1997年 | 2篇 |
1996年 | 3篇 |
1995年 | 5篇 |
1994年 | 1篇 |
1993年 | 3篇 |
1992年 | 1篇 |
1991年 | 3篇 |
1990年 | 3篇 |
1989年 | 5篇 |
1988年 | 2篇 |
1987年 | 4篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1982年 | 1篇 |
1981年 | 4篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1975年 | 1篇 |
排序方式: 共有422条查询结果,搜索用时 15 毫秒
51.
Amit Kumar Trevor Janes Subrata Chakraborty Prosenjit Daw Niklas vonWolff Raanan Carmieli Yael Diskin‐Posner David Milstein 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(11):3411-3415
We report a C?C bond‐forming reaction between benzyl alcohols and alkynes in the presence of a catalytic amount of KOtBu to form α‐alkylated ketones in which the C=O group is located on the side derived from the alcohol. The reaction proceeds under thermal conditions (125 °C) and produces no waste, making the reaction highly atom efficient, environmentally benign, and sustainable. Based on our mechanistic investigations, we propose that the reaction proceeds through radical pathways. 相似文献
52.
Silanylidene and Germanylidene Anions: Valence‐Isoelectronic Species to the Well‐Studied Phosphinidene
下载免费PDF全文
![点击此处可从《Angewandte Chemie (International ed. in English)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Dr. Mujahuddin M. Siddiqui Dr. Soumen Sinhababu Sayan Dutta Dr. Subrata Kundu Paul Niklas Ruth Annika Münch Dr. Regine Herbst‐Irmer Prof. Dietmar Stalke Dr. Debasis Koley Prof. Herbert W. Roesky 《Angewandte Chemie (International ed. in English)》2018,57(36):11776-11780
The reduction of TipMCl3 (Tip=2,4,6‐triisopropylphenyl) (M=Si, Ge) with KC8 in the presence of cyclic alkyl(amino) carbene (cAAC) afforded the acyclic silanylidene and germanylidene anions in the form of potassium salt [K(cAAC)MTip]2 (M=Si ( 1 ); Ge ( 2 )). The silanylidene and germanylidene anions are valence‐isoelectronic to the well‐studied phosphinidene and are a new class of acyclic anions of Group 14. Compounds 1 and 2 were isolated and well characterized by NMR and single‐crystal X‐ray structure analysis. Furthermore, the structure and bonding of compounds 1 and 2 was investigated by computational methods. 相似文献
53.
The mechanism and the rate of hydrogen bond-breaking in the hydration layer surrounding an aqueous protein are important ingredients required to understand the various aspects of protein dynamics, its function, and stability. Here, we use computer simulation and a time correlation function technique to understand these aspects in the hydration layer of lysozyme. Water molecules in the layer are found to exhibit three distinct bond-breaking mechanisms. A large angle orientational jump of the donor water molecule is common among all of them. In the most common ( approximately 80%) bond-breaking event in the layer, the new acceptor water molecule comes from the first coordination shell (initially within 3.5 A of the donor), and the old acceptor water molecule remains within the first coordination shell, even after the bond-breaking. This is in contrast to that in bulk water, in which both of the acceptor molecules involve the second coordination shell. Additionally, the motion of the incoming and the outgoing acceptor molecules involved is not diffusive in the hydration layer, in contrast to their observed diffusive motion in the bulk. The difference in rotational dynamics between the bulk and the hydration layer water molecules is clearly manifested in the calculated time-dependent angular van Hove self-correlation function ( G(theta, t)) which has a pronounced two-peak structure in the layer, and this can be traced to the constrained translational motion in the layer. The longevity of the surrounding hydrogen bond network is found to be significantly enhanced near a hydrophilic residue. 相似文献
54.
Anubha Sharma Sunita Gamre Siddharth Roy Dibakar Goswami Angshuman Chattopadhyay Subrata Chattopadhyay 《Tetrahedron letters》2008,49(24):3902-3905
A facile asymmetric synthesis of the octalactin lactone was developed staring from (R)-cyclohexylideneglyceraldehyde (1). The key step of the synthesis is an In-mediated diastereoselective crotylation of 1 in water, which furnished the building blocks with the required stereochemistry under operationally simple conditions. Their conversion to the appropriate intermediates, invertive esterification and a ring closing metathesis reaction furnished the target compound. 相似文献
55.
Balia Singh R Mahanta S Guchhait N 《Journal of photochemistry and photobiology. B, Biology》2008,91(1):1-8
In the present work, we have studied the interaction of proton transfer probe 1-hydroxy-2-naphthaldehyde (HN12) with Human Serum Albumin (HSA) and Bovine Serum Albumin (BSA) by steady state absorption and emission spectroscopy combined with time resolved fluorescence measurements. The measured binding constant (K) and free energy change (DeltaG) indicate a stronger affinity of HN12 molecule for HSA than BSA. Steady state anisotropy, excitation anisotropy and fluorescence resonance energy transfer (FRET) studies indicate that the probe molecule resides at the hydrophobic site of the protein environment. 相似文献
56.
Balakrishnan S. Anju Neeraja R. Nair Dr. Subrata Kundu 《Angewandte Chemie (International ed. in English)》2023,62(48):e202311523
Nitrite (NO2−) and nitric oxide (NO) interconversion is crucial for maintaining optimum NO flux in mammalian physiology. Herein we demonstrate that [ L 2CuII(nitrite)]+ moieties (in 2 a and 2 b ; where, L = Me2PzPy and Me2PzQu ) with distorted octahedral geometry undergo facile reduction to provide tetrahedral [ L 2CuI]+ (in 3 a and 3 b ) and NO in the presence of biologically relevant reductants, such as 4-methoxy-2,6-di-tert-butylphenol (4-MeO-2,6-DTBP, a tyrosine model) and N-benzyl-1,4-dihydronicotinamide (BNAH, a NAD(P)H model). Interestingly, the reaction of excess NO gas with [ L 2CuII(MeCN)2]2+ (in 1 a ) provides a putative {CuNO}10 species, which is effective in mediating the nitrosation of various nucleophiles, such as thiol and amine. Generation of the transient {CuNO}10 species in wet acetonitrile leads to NO2− as assessed by Griess assay and 14N/15N-FTIR analyses. A detailed study reveals that the bidirectional NOx-reactivity, namely, nitrite reductase (NIR) and NO oxidase (NOO), at a common CuII site, is governed by the geometric-preference-driven facile CuII/CuI redox process. Of broader interest, this study not only highlights potential strategies for the design of copper-based catalysts for nitrite reduction, but also strengthens the previous postulates regarding the involvement of red copper proteins in denitrification. 相似文献
57.
Biological molecules, in particular DNA, have shown great potential to be used as interconnects of nanodevices and computational elements. In this research, we synthesized electrically conductive gold nanowires for the first time exploiting an electroless and microwave heating method for 120-180 s. Our results indicate that DNA serves as a reducing and nonspecific capping agent for the growth of nanowires. The current voltage ( I- V) characteristics of the Au nanowires are continuous, exhibiting Ohmic behavior having low contact resistance with the gold electrodes. The nanowires have a diameter of 10-15 nm in solution and of 20-30 nm in immobilized DNA with resistivity comparable to pure metals. The method is highly selective with deposition confined to the DNA itself. The nanowires we fabricated can be used as building blocks for functional nanodevices, sensors, and optoelectronics. 相似文献
58.
JPC – Journal of Planar Chromatography – Modern TLC - An optimized method for the extraction and quantification of artemisinin using high-performance thin-layer chromatography (HPTLC)... 相似文献
59.
Dr. Subrata Kundu Prof. Dr. S. Chantal E. Stieber Dr. Maryline G. Ferrier Dr. Stosh A. Kozimor Dr. Jeffery A. Bertke Prof. Dr. Timothy H. Warren 《Angewandte Chemie (International ed. in English)》2016,55(35):10321-10325
Nitrosobenzene (PhNO) serves as a stable analogue of nitroxyl (HNO), a biologically relevant, redox‐active nitric oxide derivative. Capture of nitrosobenzene at the electron‐deficient β‐diketiminato nickel(I) complex [iPr2NNF6]Ni results in reduction of the PhNO ligand to a (PhNO)./? species coordinated to a square planar NiII center in [iPr2NNF6]Ni(η2‐ONPh). Ligand centered reduction leads to the (PhNO)2? moiety bound to NiII supported by XAS studies. Systematic investigation of structure–reactivity patterns of (PhNO)./? and (PhNO)2? ligands reveals parallels with superoxo (O2)./? and peroxo (O2)2? ligands, respectively, and forecasts reactivity patterns of the more transient HNO ligand. 相似文献
60.