全文获取类型
收费全文 | 333篇 |
免费 | 22篇 |
国内免费 | 1篇 |
专业分类
化学 | 285篇 |
晶体学 | 2篇 |
力学 | 5篇 |
数学 | 36篇 |
物理学 | 28篇 |
出版年
2024年 | 1篇 |
2023年 | 3篇 |
2022年 | 8篇 |
2021年 | 7篇 |
2020年 | 6篇 |
2019年 | 8篇 |
2018年 | 10篇 |
2017年 | 5篇 |
2016年 | 6篇 |
2015年 | 15篇 |
2014年 | 27篇 |
2013年 | 26篇 |
2012年 | 33篇 |
2011年 | 32篇 |
2010年 | 18篇 |
2009年 | 20篇 |
2008年 | 14篇 |
2007年 | 16篇 |
2006年 | 13篇 |
2005年 | 23篇 |
2004年 | 17篇 |
2003年 | 8篇 |
2002年 | 11篇 |
2001年 | 3篇 |
2000年 | 2篇 |
1999年 | 4篇 |
1998年 | 5篇 |
1997年 | 2篇 |
1995年 | 2篇 |
1993年 | 2篇 |
1991年 | 2篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1981年 | 4篇 |
1957年 | 1篇 |
排序方式: 共有356条查询结果,搜索用时 0 毫秒
71.
Heterologous Expression,Biosynthetic Studies,and Ecological Function of the Selective Gq‐Signaling Inhibitor FR900359 下载免费PDF全文
Dr. Max Crüsemann Raphael Reher Isabella Schamari Dr. Alexander O. Brachmann Dr. Tsubasa Ohbayashi Markus Kuschak Dr. Davide Malfacini Alexander Seidinger Marta Pinto‐Carbó René Richarz Tatjana Reuter Dr. Stefan Kehraus Dr. Asis Hallab Misty Attwood Prof. Dr. Helgi B. Schiöth Dr. Peter Mergaert Dr. Yoshitomo Kikuchi Prof. Dr. Till F. Schäberle Prof. Dr. Evi Kostenis Prof. Dr. Daniela Wenzel Prof. Dr. Christa E. Müller Prof. Dr. Jörn Piel Prof. Dr. Aurélien Carlier Prof. Dr. Leo Eberl Prof. Dr. Gabriele M. König 《Angewandte Chemie (International ed. in English)》2018,57(3):836-840
The cyclic depsipeptide FR900359 (FR), isolated from the tropical plant Ardisia crenata, is a strong and selective inhibitor of Gq proteins, making it an indispensable pharmacological tool to study Gq‐related processes, as well as a promising drug candidate. Gq inhibition is a novel mode of action for defense chemicals and crucial for the ecological function of FR, as shown by in vivo experiments in mice, its affinity to insect Gq proteins, and insect toxicity studies. The uncultured endosymbiont of A. crenata was sequenced, revealing the FR nonribosomal peptide synthetase (frs) gene cluster. We here provide a detailed model of FR biosynthesis, supported by in vitro enzymatic and bioinformatic studies, and the novel analogue AC‐1, which demonstrates the flexibility of the FR starter condensation domains. Finally, expression of the frs genes in E. coli led to heterologous FR production in a cultivable, bacterial host for the first time. 相似文献
72.
Interfacial tension has been used to study the adsorption at the water/1,2-dichloroethane interface of dicarbollylcobaltate(III) {(pi-(3)-1,2-B(9)C(2)H(11))(2)Co(III)(-)} of the monovalent and bivalent metals. At the limiting coverage, the area per dicarbollylcobaltate(III) anions in the monolayer found experimentally is equal to 95+/-8 ?(2). It can be assumed that the symmetry axis of the adsorbed anions is arranged parallel to the interface surface. By their effects on the surface activity of the dicarbollylcobaltate(III) anions, cations can be arranged in the following order: Mg(2+) approximately Ba(2+) approximately Pb(2+)>/=Li(+) approximately Na(+)>K(+)>NH(+)(4)>Rb(+)Tl(+) approximately Ag(+) approximately Cs(+). The parameters of Frumkin and the virial isotherms have been calculated. There is a rather strong repulsion among the adsorbed anions. To define the energy of the specific interaction between the anions and the adsorbed monolayer, the technique of E. Goddard et al. (J. Colloid Interface Sci. 24, 297 (1967)) was applied. Its application for two-phase systems permits us to define the parameters of the ion exchange reaction on the basis of measurements of interfacial tension. The ion exchange constants calculated by various methods have been compared. Copyright 2001 Academic Press. 相似文献
73.
Rik Van Deun Peter Nockemann Tatjana N. Parac-Vogt Kristof Van Hecke Luc Van Meervelt Christiane Grller-Walrand Koen Binnemans 《Polyhedron》2007,26(18):5441-5447
The near-infrared luminescence properties of three (E)-N-hexadecyl-N′,N′-dimethylamino-stilbazolium tetrakis(1-phenyl-3-methyl-4-benzoyl-5-pyrazolonato) lanthanide(III) complexes are described. These three complexes, containing trivalent neodymium, erbium and ytterbium, respectively, show near-infrared luminescence in acetonitrile solution upon UV irradiation. Luminescence decay times have been measured. The complexes consist of a positively charged hemicyanine chromophore with a long alkyl chain and a tetrakis(pyrazolonato) lanthanide(III) anion. Because of the absence of an -hydrogen atom in the pyrazolonato ligands, and because of the saturation of the coordination sphere by four bidentate ligands, the luminescence properties are enhanced when compared to, e.g. quinolinate complexes. 相似文献
74.
An artificial neural network (ANN) model for the prediction of retention times in high-performance liquid chromatography (HPLC) was developed and optimized. A three-layer feed-forward ANN has been used to model retention behavior of nine phenols as a function of mobile phase composition (methanol-acetic acid mobile phase). The number of hidden layer nodes, number of iteration steps and the number of experimental data points used for training set were optimized. By using a relatively small amount of experimental data (25 experimental data points in the training set), a very accurate prediction of the retention (percentage normalized differences between the predicted and the experimental data less than 0.6%) was obtained. It was shown that the prediction ability of ANN model linearly decreased with the reduction of number of experiments for the training data set. The results obtained demonstrate that ANN offers a straightforward way for retention modeling in isocratic HPLC separation of a complex mixture of compounds widely different in pKa and log Kow values. 相似文献
75.
Rasheed Rashed Taleb Mansoor Hadeel S. Abdullah Thamer Adnan Juzsakova Tatjana Al-Jammal Noor Salman Ali Dawood Al-Shaikhly Rasha R. Le Phuoc Cuog Domokos Endre Abdulla Thaer A. 《Journal of Thermal Analysis and Calorimetry》2021,145(2):297-307
Journal of Thermal Analysis and Calorimetry - This paper deals with an advanced colorimetric method used to determine the catalase mimetic activity of V2O5 nanoparticles by measuring the decrease... 相似文献
76.
Oksana V. Dudka Vjacheslav A. Ksenofontov Alexei A. Mazilov Tatjana I. Mazilova Evgenij V. Sadanov 《辐射效应与固体损伤》2016,171(7-8):606-614
Using low-temperature field ion microscope techniques, we studied at the atomic level the elementary events of radiation-induced surface diffusion of tungsten adatoms on the ideally pristine surface. The experiments on surface-damage formation and adatom displacements have been performed in situ with a source of neutral helium atoms with an energy of 5?keV. It was demonstrated that the low-energy He atomic bombardment at grazing incidence was able to induce a substantial surface mobility of adatoms. Most of the radiation-induced adatom displacements were oriented along the direction of irradiation. The long impact-induced jumps of adatoms, spanning more than a nearest-neighbor distance, were revealed. Performed molecular dynamics simulations reproduce the general experimental trends and conclusions. 相似文献
77.
Stefan Badza Tatjana Jevremovic 《Journal of Radioanalytical and Nuclear Chemistry》2014,299(1):427-431
The main motivation in studying different types of rice was to determine how processing of rice affects its mineral composition, and to compare how it affects rice dietary intake. Specifically the estimated difference in between the brown and white rice produced in Japan and California are studied. These various rice samples were analyzed using neutron activation analysis technique available at the Utah Nuclear Engineering Program (UNEP). Samples were prepared using novel technique developed at UNEP and submitted for short and long irradiation. The detected elements were As, Br, Cl, Cd, Mn, Na, K. The concentrations of Mn, K and Na are significantly higher in the brown then in the white rice, while As, Br and Cl have more homogeneous presence and therefore smaller difference in concentration. Elemental concentration was compared with The Institute of Medicine (IOM) in the United States values of recommended dietary allowance and Food and Drug Administration (FDA) limits for harmful elements. From these measurements, only the concentration of Mn in rice satisfies daily needs in the range set as defined by IOM. The concentrations of potentially harmful elements are lower than FDA limits. 相似文献
78.
Different capillary electrophoretic techniques were investigated and compared for the separation of low-molecular-mass phenolic
and neutral lignin degradation compounds. Simple capillary zone electrophoresis (CZE) was not suited for this problem. Switching
to micellar electrokinetic capillary chromatography (MEKC) by adding micelle-forming reagents to the carrier electrolyte enhanced
the separation performance considerably. Alternatively, microemulsion electrokinetic chromatography (MEEKC) was investigated.
This is a CE technique in which analytes interact with moving oil droplets present in a microemulsion buffer. Using the optimized
carrier electrolyte systems and a 60 cm×50 μm I.D. bubble cell capillary it was possible to analyse solutions of different
wood digestion procedures and to investigate differences in lignin degradation products during use of different kinds of wood
(eucalyptus, beech, scotch pine and acacia).
Received August 25, 1999. Revision April 13, 2000 相似文献
79.
Peter Nockemann Dr. Michael Pellens Kristof Van Hecke Dr. Luc Van Meervelt Prof. Dr. Johan Wouters Prof. Dr. Ben Thijs Dr. Evert Vanecht Tatjana N. Parac‐Vogt Prof. Dr. Hasan Mehdi Stijn Schaltin Jan Fransaer Prof. Dr. Stefan Zahn Barbara Kirchner Prof. Dr. Koen Binnemans Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(6):1849-1858
A series of nitrile‐functionalized ionic liquids were found to exhibit temperature‐dependent miscibility (thermomorphism) with the lower alcohols. Their coordinating abilities toward cobalt(II) ions were investigated through the dissolution process of cobalt(II) bis(trifluoromethylsulfonyl)imide and were found to depend on the donor abilities of the nitrile group. The crystal structures of the cobalt(II) solvates [Co(C1C1CNPyr)2(Tf2N)4] and [Co(C1C2CNPyr)6][Tf2N]8, which were isolated from ionic‐liquid solutions, gave an insight into the coordination chemistry of functionalized ionic liquids. Smooth layers of cobalt metal could be obtained by electrodeposition of the cobalt‐containing ionic liquids. 相似文献
80.
Tatjana M. Trtić‐Petrović Ksenija R. Kumrić Jelena S. Đorđević Goran T. Vladisavljević 《Journal of separation science》2010,33(13):2002-2009
Transport behaviour of Lu(III) across a polypropylene hollow fibre‐supported liquid membrane containing di(2‐ethylhexyl)phosphoric acid (DEHPA) in dihexyl ether as a carrier has been studied. The donor phase was LuCl3 in the buffer solution consisting of 0.2 M sodium acetate at pH 2.5–5.0. A miniaturised system with a single hollow fibre has been operated in a batch mode. The concentration of Lu(III) was determined by indirect voltammetric method using Zn–EDTA complex. The effect of pH and volume of the donor phase, DEHPA concentration in the organic (liquid membrane) phase, the time of extraction and the content of the acceptor phase on the Lu(III) extraction and stripping behaviour was investigated. The results were discussed in terms of the pertraction and removal efficiency, the memory effect and the mean flux of Lu(III). The optimal conditions for the removal of 177Lu(III) from labelled 177Lu‐radiopharmaceuticals were discussed and identified. The removal efficiency of Lu(III) greater than 99% was achieved at pH of the donor phase between 3.5 and 5.0 using DEHPA concentration in the organic phase of 0.47 M and the ratio of the donor to the acceptor phase of 182. 相似文献