全文获取类型
收费全文 | 339篇 |
免费 | 4篇 |
国内免费 | 1篇 |
专业分类
化学 | 222篇 |
晶体学 | 35篇 |
力学 | 3篇 |
数学 | 19篇 |
物理学 | 65篇 |
出版年
2022年 | 3篇 |
2021年 | 4篇 |
2019年 | 4篇 |
2018年 | 3篇 |
2017年 | 3篇 |
2016年 | 5篇 |
2014年 | 4篇 |
2013年 | 8篇 |
2012年 | 7篇 |
2011年 | 8篇 |
2010年 | 6篇 |
2009年 | 6篇 |
2008年 | 10篇 |
2007年 | 10篇 |
2006年 | 9篇 |
2005年 | 11篇 |
2004年 | 6篇 |
2003年 | 8篇 |
2002年 | 5篇 |
2001年 | 11篇 |
2000年 | 15篇 |
1999年 | 18篇 |
1998年 | 6篇 |
1997年 | 8篇 |
1996年 | 13篇 |
1995年 | 15篇 |
1994年 | 7篇 |
1993年 | 9篇 |
1992年 | 4篇 |
1991年 | 3篇 |
1990年 | 13篇 |
1989年 | 13篇 |
1988年 | 8篇 |
1987年 | 7篇 |
1986年 | 3篇 |
1985年 | 3篇 |
1984年 | 9篇 |
1983年 | 2篇 |
1982年 | 6篇 |
1981年 | 5篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1978年 | 6篇 |
1977年 | 12篇 |
1976年 | 3篇 |
1975年 | 3篇 |
1974年 | 3篇 |
1973年 | 3篇 |
1880年 | 2篇 |
1865年 | 2篇 |
排序方式: 共有344条查询结果,搜索用时 15 毫秒
11.
Electrospray ionization mass spectrometry (ESI-MS) is used to evaluate the metal binding selectivities of an array of novel caged macrocycles for silver, gold, copper, nickel, zinc, iron, lead, manganese and alkali metal ions. It is found that five of the new compounds display silver selectivity, and their relative affinities for various metals depend on the type, number, and arrangement of heteroatoms (N, O), the cavity size, and the presence of aromatic substituents. Alkali metal cation binding studies are used to evaluate the size-selectivities of the cavities of the macrocycles. Electronic structure calculation by B3LYP density function theory methods were used to model the metal complexes. The presence of nitrogen atoms in the macrocyclic ring is essential for silver selectivity over other transition metals and alkali metal ions, and the presence of aromatic groups also enhances silver avidity. Macrocycle 3, a triaza-18-crown-6 analog modified with two phenyl groups and a cage group, is capable of selective extraction of Ag+ from aqueous solutions in the presence of other transition metal ions and the most common alkali and alkaline earth metal ions. 相似文献
12.
Marchand C Nguyen CH Ward B Sun JS Bisagni E Garestier T Hélène C 《Chemistry (Weinheim an der Bergstrasse, Germany)》2000,6(9):1559-1563
Sequence-specific DNA recognition can be achieved by oligonucleotides that bind to the major groove of oligopyrimidine x oligopurine sequences. These intermolecular structures could be used to modulate gene expression and to create new tools for molecular biology. Here we report the synthesis and biochemical characterization of triple helix-specific DNA cleaving reagents. It is based on the previously reported triplex-specific ligands, benzo[e]pyridoindole (BePI) and benzo[g]pyridoindole (BgPI), covalently attached to ethylenediaminotetraacetic acid (EDTA). In the presence of iron, a reducing agent and molecular oxygen, BgPI-EDTA x FeII but not BePI-EDTA x FeII induced a double-stranded cut in a plasmid DNA at the single site where a triplex-forming oligonucleotide binds. At single nucleotide resolution, it was found that upon triplex formation BePI-EDTA x FeII led to cleavage of the pyrimidine strand and protection of the purine strand. BgPI-EDTA x FeII cleaved both strands with similar efficiency. The difference in cleavage efficiency between the two conjugates was rationalized by the location of the EDTA x FeII moiety with respect to the grooves of DNA (major groove: BePI-EDTA x FeII, minor groove: BgPI-EDTA x FeII). This work paves the way to the development of a new class of triple helix directed DNA cleaving reagents. Such molecules will be of interest for sequence-specific DNA cleavage and for investigating triple-helical structures, such as H-DNA, which could play an important role in the control of gene expression in vivo. 相似文献
13.
Maurice Guillot André Marchand François Tcheou H. Le Gall 《Zeitschrift für Physik B Condensed Matter》1982,49(3):221-228
On single crystals of holmium iron garnet (HoIG), magnetic properties have been studied in magnetic field up to 150kOe applied parallel to the main crystallographic directions in the 4.2–300K temperature range. Above 130 K, the magnetization is isotropic and linear magnetic field dependent as previously found in polycrystals and predicted by Néel's ferrimagnetic theory. Nevertheless the paramagnetic Curie temperature is much higher than the polycrystal value. Below 130K, due to the onset of the umbrella structure, the ferrite magnetization presents a non linear field variation with [111] as easy direction. The field evolutions of the anisotropy constants (K
1 andK
2) were calculated. Optical absorption measurements of both 585I
6 and 5I
85I
7 transitions are reported and compared to the results of the literature in terms of inequivalent magnetic sites. 相似文献
14.
Résumé Le diagramme des équilibres liquide-solide du système fluorure de rubidium-fluorure d'hydrogène a été tracé dans sa totalité. Six espèces stables se manifestent RbF · nHF (avecn=7, 4, 3, 2, 3/2, 1). Un septième composé dont la composition probable est 2RbF · 5HF se manifeste à l'état métastable.
Liquid-solid equilibria are studied in the complete binary system RbF-HF. Several compounds are observed: RbF ·nHF withn=7, 4, 3, 2, 3/2 and 1. A seventh compound, 2RbF · 5HF, is detected as an unstable form.
Zusammenfassung Flüssig-fest Gleichgewichte des Binärsystems RbF-HF wurden umfassend untersucht. Sechs stabile Verbindungen wurden beobachtet: RbF ·n HF (n=7, 4, 3, 2, 3/2 und 1). Eine siebente Verbindung, 2 RbF · 5 HF ist metastabil.
- RbF-HF. RbF·nHF =7,4,3,2, 3/2 1. — 2RbF·5HF — .相似文献
15.
16.
Fernaldo Richtia Winnerdy Bla Bakalar Poulomi Das Brahim Heddi Adrien Marchand Frdric Rosu Valrie Gabelica Anh Tun Phan 《Chemical science》2021,12(20):7151
Cations are critical for the folding and assembly of nucleic acids. In G-quadruplex structures, cations can bind between stacked G-tetrads and coordinate with negatively charged guanine carbonyl oxygens. They usually exchange between binding sites and with the bulk in solution with time constants ranging from sub-millisecond to seconds. Here we report the first observation of extremely long-lived K+ and NH4+ ions, with an exchange time constant on the order of an hour, when coordinated at the center of a left-handed G-quadruplex DNA. A single-base mutation, that switched one half of the structure from left- to right-handed conformation resulting in a right–left hybrid G-quadruplex, was shown to remove this long-lived behaviour of the central cation.An extremely long-lived cation has been detected in left-handed G-quadruplexes. 相似文献
17.
M. M. Mason J. S. Morris V. L. Spate C. K. Baskett T. A. Nichols T. L. Horsman L. Le Marchand L. N. Kolonel S. Yukimoto 《Journal of Radioanalytical and Nuclear Chemistry》1998,232(1-2):29-34
Haem peroxidases are globular proteins with an iron-porphyrin complex as prosthetic group. They catalyze the oxidation of
substrate by peroxides, frequently via free-radical intermediates. The catalytic cycle involves changes in the redox states
of the prosthetic group, that can be monitored by changes in the intense absorption spectra. During the past decades, considerable
scientific effort has been put into the elucidation of the mechanisms of reactions catalyzed by these enzymes. Radiation-chemical
techniques have made an important contribution by providing information on the redox states of the enzymes and their interconversions,
as well as on the properties of the free-radical intermediates involved. 相似文献
18.
Henry W. Orton Dr. Jan Stanek Dr. Tobias Schubeis Dylan Foucaudeau Claire Ollier Dr. Adrian W. Draney Dr. Tanguy Le Marchand Dr. Diane Cala-De Paepe Prof. Dr. Isabella C. Felli Prof. Dr. Roberta Pierattelli Prof. Dr. Sebastian Hiller Dr. Wolfgang Bermel Dr. Guido Pintacuda 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(6):2400-2405
19.
John Cagnol Irena Lasiecka Catherine Lebiedzik Richard Marchand 《Comptes Rendus Mathematique》2006,342(9):711-716
This note is concerned with the non-linear shallow shell model introduced in 1966 by W.T. Koiter, and later studied by M. Bernadou and J.T. Oden. We show the uniqueness of the solution to the dynamical model and that this solution is continuous with respect to the initial data. To cite this article: J. Cagnol et al., C. R. Acad. Sci. Paris, Ser. I 342 (2006). 相似文献
20.
Anaïs Giustiniani Philippe Gugan Manon Marchand Christophe Poulard Wiebke Drenckhan 《Macromolecular rapid communications》2016,37(18):1527-1532
Macrocellular silicone polymers are obtained after solidification of the continuous phase of a poly(dimethylsiloxane) emulsion, which contains poly(ethylene glycol) drops of sub‐millimetric dimensions. Coalescence of the liquid template emulsion is prohibited by a reactive blending approach. The relationship is investigated in detail between the interfacial properties and the emulsion stability, and micro‐ and millifluidic techniques are used to generate macrocellular polymers with controlled structural properties over a wider range of cell sizes (0.2–2 mm) and volume fractions of the continuous phase (0.1%–40%). This approach could easily be transferred to a wide range of polymeric systems.