全文获取类型
收费全文 | 522篇 |
免费 | 48篇 |
国内免费 | 1篇 |
专业分类
化学 | 481篇 |
力学 | 4篇 |
数学 | 42篇 |
物理学 | 44篇 |
出版年
2023年 | 8篇 |
2022年 | 13篇 |
2021年 | 14篇 |
2020年 | 29篇 |
2019年 | 29篇 |
2018年 | 13篇 |
2017年 | 5篇 |
2016年 | 25篇 |
2015年 | 23篇 |
2014年 | 39篇 |
2013年 | 23篇 |
2012年 | 51篇 |
2011年 | 44篇 |
2010年 | 33篇 |
2009年 | 27篇 |
2008年 | 32篇 |
2007年 | 24篇 |
2006年 | 24篇 |
2005年 | 29篇 |
2004年 | 17篇 |
2003年 | 12篇 |
2002年 | 14篇 |
2001年 | 10篇 |
2000年 | 7篇 |
1999年 | 5篇 |
1998年 | 4篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1995年 | 2篇 |
1993年 | 3篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1985年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1960年 | 1篇 |
排序方式: 共有571条查询结果,搜索用时 15 毫秒
111.
Jan W. Bats Tanja M. Frost A. Stephen K. Hashmi 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(9):1081-1083
The title compounds, N‐[5‐(4‐chlorophenyl)furan‐2‐ylmethyl]‐4‐methyl‐N‐(prop‐2‐ynyl)benzenesulfonamide, (Ia), and N‐[5‐(2‐chlorophenyl)furan‐2‐ylmethyl]‐4‐methyl‐N‐(prop‐2‐ynyl)benzenesulfonamide, (Ib), both C21H18ClNO3S, have isomorphous crystal structures. The crystal packing is mainly determined by intermolecular C—H?O and C—H?π interactions. These interactions are very similar in (Ia) and (Ib). Additional intermolecular C—H?Cl interactions appear less important and are different in (Ia) and (Ib). The different positions of the Cl atoms result in small variations of the crystal packing of the two compounds. 相似文献
112.
Hu Xing Yiting Zhang Markus Krmer Ann-Kathrin Kissmann Marius Henkel Tanja Weil Uwe Knippschild Frank Rosenau 《Molecules (Basel, Switzerland)》2022,27(17)
Recent studies have demonstrated that changes in the abundance of the intestinal bacterium Blautia producta, a potential probiotic, are closely associated with the development of various diseases such as obesity, diabetes, some neurodegenerative diseases, and certain cancers. However, there is still a lack of an effective method to detect the abundance of B. producta in the gut rapidly. Especially, DNA aptamers are now widely used as biometric components for medical testing due to their unique characteristics, including high chemical stability, low production cost, ease of chemical modification, low immunogenicity, and fast reproducibility. We successfully obtained a high-affinity nucleic acid aptamer library (B.p-R14) after 14 SELEX rounds, which efficiently discriminates B. producta in different analysis techniques including fluorometric suspension assays or fluorescence microscopy from other major gut bacteria in complex mixtures and even in human stool samples. These preliminary findings will be the basis towards aptamer-based biosensing applications for the fast and reliable monitoring of B. producta in the human gut microbiome. 相似文献
113.
Alja Prah Tanja Gavrani Andrej Perdih Marija Sollner Dolenc Janez Mavri 《Molecules (Basel, Switzerland)》2022,27(19)
Monoamine oxidases (MAOs) are an important group of enzymes involved in the degradation of neurotransmitters and their imbalanced mode of action may lead to the development of various neuropsychiatric or neurodegenerative disorders. In this work, we report the results of an in-depth computational study in which we performed a static and a dynamic analysis of a series of substituted β-carboline natural products, found mainly in roasted coffee and tobacco smoke, that bind to the active site of the MAO-A isoform. By applying molecular docking in conjunction with structure-based pharmacophores and molecular dynamics simulations coupled with dynamic pharmacophores, we extensively investigated the geometric aspects of MAO-A binding. To gain insight into the energetics of binding, we used the linear interaction energy (LIE) method and determined the key anchors that allow productive β-carboline binding to MAO-A. The results presented herein could be applied in the rational structure-based design and optimization of β-carbolines towards preclinical candidates that would target the MAO-A enzyme and would be applicable especially in the treatment of mental disorders such as depression. 相似文献
114.
Tanja Kunz Dr. Claudio Schrenk Prof. Dr. Andreas Schnepf 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(29):7210-7217
The reaction system GeCl2 ⋅ dioxane/LiSTsi (Tsi=C(SiMe3)3) opens a fruitful area in germanium chemistry, depending on the stoichiometry and solvent used during the reaction. For example, the reaction of GeCl2 ⋅ dioxane in toluene with two equivalents of the thiolate gives the expected germylene Ge(STsi)2 in excellent yield. This germylene readily reacts with hydrogen and acetylene, however, in a non-selective way. By using an excess amount of the thiolate and toluene as the solvent, the germanide [Ge(STsi)3][Li(thf)] is obtained. Performing the same reaction in thf leads to a C−H activation of thf to give (H7C4O)Ge[STsi](μ2-S)2Ge[STsi]2, in which the thf molecule is still intact. Using a sub-stoichiometric amount of the thiolate leads to the heteroleptic compound [ClGe(STsi)]2 and to the insertion product (thf)Ge[S-GeCl2-Tsi]2, in which additional GeCl2 molecules insert into the C−S bonds of Ge(STsi)2. The synthesis and the experimentally determined structures of all compounds are presented together with first reactivity studies of Ge(STsi)2. 相似文献
115.
Florian Kleemiss Erna K. Wieduwilt Dr. Emanuel Hupf Ming W. Shi Dr. Scott G. Stewart Prof. Dylan Jayatilaka Dr. Michael J. Turner Prof. Kunihisa Sugimoto Prof. Eiji Nishibori Prof. Dr. Tanja Schirmeister Dr. Thomas C. Schmidt Prof. Dr. Bernd Engels PD Dr. Simon Grabowsky 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(10):3407-3419
The crystal interaction density is generally assumed to be a suitable measure of the polarization of a low-molecular weight ligand inside an enzyme, but this approximation has seldomly been tested and has never been quantified before. In this study, we compare the crystal interaction density and the interaction electrostatic potential for a model compound of loxistatin acid (E64c) with those inside cathepsin B, in solution, and in vacuum. We apply QM/MM calculations and experimental quantum crystallography to show that the crystal interaction density is indeed very similar to the enzyme interaction density. Less than 0.1 e are shifted between these two environments in total. However, this difference has non-negligible consequences for derived properties. 相似文献
116.
Dr. Francisco Javier Ortiz-López M. Sc. Daniel Carretero-Molina Dr. Marina Sánchez-Hidalgo M. Sc. Jesús Martín Dr. Ignacio González M. Sc. Fernando Román-Hurtado Dr. Mercedes de la Cruz Dr. Sergio García-Fernández Dr. Fernando Reyes M. Sc. Julia Patricia Deisinger Dr. Anna Müller Dr. Tanja Schneider Dr. Olga Genilloud 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(31):12754-12758
Lantibiotics are ribosomally synthesized and post-translationally modified peptides (RiPPs) characterized by the presence of lanthionine or methyllanthionine rings and their antimicrobial activity. Cacaoidin, a novel glycosylated lantibiotic, was isolated from a Streptomyces cacaoi strain and fully characterized by NMR, mass spectrometry, chemical derivatization approaches and genome analysis. The new molecule combines outstanding structural features, such as a high number of d -amino acids, an uncommon glycosylated tyrosine residue and an unprecedented N,N-dimethyl lanthionine. This latter feature places cacaoidin within a new RiPP family located between lanthipeptides and linaridins, here termed lanthidins. Cacaoidin displayed potent antibacterial activity against Gram-positive pathogens including Clostridium difficile. The biosynthetic gene cluster showed low homology with those of other known lanthipeptides or linaridins, suggesting a new RiPP biosynthetic pathway. 相似文献
117.
JPC – Journal of Planar Chromatography – Modern TLC - Experiments and calculations show the importance of analytical management to reliable analytical results. A method with a... 相似文献
118.
119.
Colloids for Catalysts: A Concept for the Preparation of Superior Catalysts of Industrial Relevance
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. Jonathan Quinson Sara Neumann Tanja Wannmacher Laura Kacenauskaite Masanori Inaba Jan Bucher Francesco Bizzotto Dr. Søren B. Simonsen Dr. Luise Theil Kuhn Dajana Bujak Dr. Alessandro Zana Prof. Dr. Matthias Arenz Dr. Sebastian Kunz 《Angewandte Chemie (International ed. in English)》2018,57(38):12338-12341
Compared to conventional preparation methods for supported heterogeneous catalysts, the use of colloidal nanoparticles (NPs) allows for a precise control over size, size distribution, and distribution/location of the NPs on the support. However, common colloidal syntheses have restrictions that limit their applicability for industrial catalyst preparation. We present a simple, surfactant‐free, and scalable preparation method for colloidal NPs to overcome these restrictions. We demonstrate how precious‐metal NPs are prepared in alkaline methanol, how the particle size can be tuned, and how supported catalysts are obtained. The potential of these colloids in the preparation of improved catalysts is demonstrated by two examples from heterogeneous catalysis and electrocatalysis. 相似文献
120.
Stimulus‐Triggered Formation of an Anion–Cation Exciplex in Copper(I) Complexes as a Mechanism for Mechanochromic Phosphorescence
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)
Benjamin Hupp Dr. Jörn Nitsch Tanja Schmitt Dr. Rüdiger Bertermann Dr. Katharina Edkins Florian Hirsch Prof. Dr. Ingo Fischer Michael Auth Dr. Andreas Sperlich Priv.‐Doz. Dr. Andreas Steffen 《Angewandte Chemie (International ed. in English)》2018,57(41):13671-13675
The investigation of the mechanisms of mechanochromic luminescence is of fundamental importance for the development of materials for photonic sensors, data storage, and luminescence switches. The structural origin of this phenomenon in phosphorescent molecular systems is rarely known and thus the formulation of structure–property relationships remains challenging. Changes in the M–M interactions have been proposed as the main mechanism with d10 coinage metal compounds. Herein, we describe a new mechanism—a mechanically induced reversible formation of a cation–anion exciplex based on Cu–F interactions—that leads to highly efficient mechanochromic phosphorescence and unusual large emission shifts from UV‐blue to yellow for CuI complexes. The low‐energy luminescence is thermo‐ and vaporesponsive, thus allowing the generation of white light as well as for recovering the original UV‐blue emission. 相似文献