全文获取类型
收费全文 | 184篇 |
免费 | 6篇 |
专业分类
化学 | 156篇 |
力学 | 2篇 |
数学 | 10篇 |
物理学 | 22篇 |
出版年
2022年 | 2篇 |
2021年 | 5篇 |
2020年 | 6篇 |
2019年 | 1篇 |
2018年 | 1篇 |
2017年 | 2篇 |
2016年 | 4篇 |
2015年 | 2篇 |
2014年 | 7篇 |
2013年 | 13篇 |
2012年 | 17篇 |
2011年 | 12篇 |
2010年 | 8篇 |
2009年 | 9篇 |
2008年 | 10篇 |
2007年 | 12篇 |
2006年 | 11篇 |
2005年 | 11篇 |
2004年 | 7篇 |
2003年 | 6篇 |
2002年 | 5篇 |
2000年 | 2篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1992年 | 1篇 |
1989年 | 2篇 |
1988年 | 3篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1982年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1977年 | 1篇 |
1968年 | 1篇 |
1963年 | 3篇 |
1957年 | 1篇 |
1954年 | 1篇 |
1952年 | 1篇 |
1949年 | 1篇 |
1948年 | 2篇 |
1947年 | 7篇 |
1940年 | 1篇 |
1938年 | 2篇 |
排序方式: 共有190条查询结果,搜索用时 15 毫秒
151.
152.
Identifying porous cage subsets in the Cambridge Structural Database using topological data analysis
As rationally designable materials, the variety and number of synthesised metal–organic cages (MOCs) and organic cages (OCs) are expected to grow in the Cambridge Structural Database (CSD). In this regard, two of the most important questions are, which structures are already present in the CSD and how can they be identified? Here, we present a cage mining methodology based on topological data analysis and a combination of supervised and unsupervised learning that led to the derivation of – to the best of our knowledge – the first and only MOC dataset of 1839 structures and the largest experimental OC dataset of 7736 cages, as of March 2022. We illustrate the use of such datasets with a high-throughput screening of MOCs and OCs for xenon/krypton separation, important gases in multiple industries, including healthcare.We mined the Cambridge Structural Database for porous cages using topological data analysis, which resulted in the first and only dataset of metal-organic cages and the largest dataset of organic cages. 相似文献
153.
154.
Vesicles are of great interest as drug delivery system or models for cell membranes. For many applications, it is necessary
to produce vesicles which are unilamellar, monodisperse, easy to adjust in size, and which can be filled with various types
of active compounds. In a series of experiments, we produced giant vesicles with dimension of several millimeters by phase
transfer processes. This new technique allowed synthesizing defined vesicles with lipid and surfactant membranes. The preparation
of these aggregates occurred in two steps. First, we filled some amount of water into a cuvette and covered this liquid with
an oil phase. Surfactants or lipids were solved either in the water or the oil phase. In the second step, a water droplet
filled with methyl blue and saccharose was formed with a syringe in the oil phase. Due to density difference, the water droplet
passed the plane oil/water interface and during this process it was transformed into a vesicle. The giant liposomes, thus
formed, showed a high sensitivity against variations of the osmotic pressure, and their stability reached from seconds to
hours. Due to the phase transfer process, the vesicle membranes often contained incorporated lenses of oil. If this hydrophobic
liquid was released from the membrane, the vesicles decayed into smaller liposomes with a broad particle size distribution. 相似文献
155.
Jonathan C. Collings Dr. Suk‐Yue Poon Dr. Céline Le Droumaguet Dr. Marina Charlot Dr. Claudine Katan Dr. Lars‐Olof Pålsson Dr. Andrew Beeby Dr. Jackie A. Mosely Dr. Hanns Martin Kaiser Dieter Kaufmann Prof. Dr. Wai‐Yeung Wong Prof. Dr. Mireille Blanchard‐Desce Dr. Todd B. Marder Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(1):198-208
Two series of related donor–acceptor conjugated dipolar, pseudo‐quadrupolar (V‐shaped) and octupolar molecular systems based on the p‐dimesitylborylphenylethynylaniline core, namely, 4‐(4‐dimesitylborylphenylethynyl)‐N,N‐dimethylaniline, 4‐[4‐(4‐dimesitylborylphenylethynyl)phenylethynyl]‐N,N‐dimethylaniline, 3,6‐bis(4‐dimesitylborylphenylethynyl)‐N‐n‐butylcarbazole and tris[4‐(4‐dimesitylborylphenylethynyl)phenyl]amine, and on the E‐p‐dimesitylborylethenylaniline motif, namely, E‐4‐dimesitylborylethenyl‐N,N‐di(4‐tolyl)aniline, 3,6‐bis(E‐dimesitylborylethenyl)‐N‐n‐butylcarbazole and tris(E‐4‐dimesitylborylethenylphenyl)amine have been synthesised by palladium‐catalyzed cross‐coupling and hydroboration routes, respectively. Their absorption and emission maxima, fluorescence lifetimes and quantum yields have been obtained and their two‐photon absorption (TPA) spectra and TPA cross‐sections have been examined. Of these systems, the octupolar compound tris(E‐4‐dimesitylborylethenylphenyl)amine has been shown to exhibit the largest TPA cross‐section among the two series of approximately 1000 GM at 740 nm. Its TPA performance is comparable to those of other triphenylamine‐based octupoles of similar size. The combination of such large TPA cross‐sections and high emission quantum yields, up to 0.94, make these systems attractive for applications involving two‐photon excited fluorescence (TPEF). 相似文献
156.
Maria Andreea Nistor Simona Gabriela Muntean Bianca Maranescu Aurelia Visa 《应用有机金属化学》2020,34(11):e5939
A very intense study class of complex porous materials, metal–organic frameworks (MOFs), composed of diverse central metallic ions attached to organic linkers, was used in this study as adsorbant materials from wastewaters. Phosphonate MOFs were prepared by the reaction of divalent inorganic salts (CoSO4 · 7H2O, NiSO4 · 6H2O, CuSO4 · 5H2O,) with vinyl phosphonic acid in hydrothermal conditions, obtaining cobalt, nickel, and copper vinylphosphonate (CoVP, NiVP, and CuVP). During synthesis the experimental conditions were varied in terms of time, temperature, and pH. The synthesized materials were characterized by Fourier transform infrared, thermogravimetric analysis, scanning electron microscopy, and X-ray crystallography. The efficiency of MOFs as adsorbents was investigated for diverse initial dye concentrations at different pH values and at three temperatures (25, 40, and 55°C). The synthesized materials presented good efficiency in the elimination of anionic as well as cationic type of dyes from aqueous solutions. The highest adsorption capacities were obtained working at optimum solution pH 4.2 for Acid Orange 7 and 10 for Basic Fuchsine, using 1 g/L of MOFs at room temperature (25°C). The adsorption capacities increase in the following order: CuVP < NiVP < CoVP. 相似文献
157.
158.
159.
Aurelia Magdalena Dianu Marius Iordache 《International journal of environmental analytical chemistry》2016,96(4):373-386
Uranium concentration levels in surface waters are of great importance because uranium presents both chemical and radiological hazard to the environment. The subject of this article is to establish that spectrophotometric method for uranium evaluation in effluents collected from liquid waste treatment generated during fabrication of nuclear fuel elements could be replaced by the optical fluorimetric technique. Both methods are briefly described. The comparison of the two methods was carried out with regard to international standards and national regulations offering from a statistical point of view a useful approach to compare two analytical measurement techniques. This methodology can be applied to any other measurement procedures. A discussion about the compliance of the fluorimetric analytical method with the mandatory discharge level of uranium concentration in surface waters is also presented. 相似文献
160.
Aurelia Tar Mihail Barboiu Yves-Marie Legrand Constantin Luca 《Journal of inclusion phenomena and macrocyclic chemistry》2008,60(1-2):35-41
The stability of complexes formed by a series of Schiff-base lariat ethers, derived from 4,13-diaza-18-crown-6, 1 with Ag+, Pb2+, Cu2+ cations, has been comparatively determined, in methanol: dichloromethane solution. We present here the synthesis and an interesting
competitive potentiometry method useful for the stability constant determination for a new family of Schiff-base bibracchial
lariat ethers. The stability constants and the selectivity in competitive complexation of Ag+, Pb2+ and Cu2+ cations by macrocyclic receptors 1–7 (L), can be accurately evaluated and species distribution diagrams can be calculated for individual system. In all cases
further functionalization of bibracchial lariat ethers 2–7 is accompanied by an increasing of the selectivity, relative to the complexes of the initial 4,13-diaza-18-crown-6 macrocycle
1. 相似文献