全文获取类型
收费全文 | 509篇 |
免费 | 19篇 |
国内免费 | 1篇 |
专业分类
化学 | 362篇 |
晶体学 | 1篇 |
力学 | 6篇 |
数学 | 64篇 |
物理学 | 96篇 |
出版年
2023年 | 6篇 |
2022年 | 5篇 |
2021年 | 14篇 |
2020年 | 14篇 |
2019年 | 14篇 |
2018年 | 5篇 |
2017年 | 4篇 |
2016年 | 17篇 |
2015年 | 13篇 |
2014年 | 18篇 |
2013年 | 23篇 |
2012年 | 24篇 |
2011年 | 36篇 |
2010年 | 34篇 |
2009年 | 24篇 |
2008年 | 44篇 |
2007年 | 46篇 |
2006年 | 33篇 |
2005年 | 41篇 |
2004年 | 20篇 |
2003年 | 15篇 |
2002年 | 23篇 |
2001年 | 9篇 |
2000年 | 9篇 |
1999年 | 3篇 |
1998年 | 1篇 |
1997年 | 5篇 |
1996年 | 4篇 |
1995年 | 2篇 |
1994年 | 4篇 |
1993年 | 1篇 |
1989年 | 1篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1983年 | 4篇 |
1982年 | 4篇 |
1979年 | 1篇 |
1973年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有529条查询结果,搜索用时 265 毫秒
51.
Gareth P. Keeley Niall McEvoy Shishir Kumar Nikos Peltekis Marcel Mausser Georg S. Duesberg 《Electrochemistry communications》2010,12(8):1034-1036
This communication describes the electrochemical properties of thin pyrolytic carbon (PyC) films created using a reliable, non-catalytic chemical vapour deposition (CVD) process. After deposition, the electron transfer characteristics of the films are optimised using a simple oxygen plasma treatment. The redox probes Ru(NH3)63+/2+, Fe(CN)63?/4? and Fe3+/2+ are employed to demonstrate that the resulting material is endowed with a large electrochemical surface area and outstanding electron transfer properties. Atomic force microscopy (AFM), Raman and X-ray photoelectron spectroscopy (XPS) are used to elucidate the morphology and chemical composition of the electrode surfaces. This material represents a new class of carbon electrode, and its large densities of edge-plane sites and oxygenated functionalities make it an ideal candidate for electrochemical sensor applications. 相似文献
52.
Quantum dots (QDs) are inorganic semiconductor nanocrystals that have unique optoelectronic properties responsible for bringing
together multidisciplinary research to impel their potential bioanalytical applications. In recent years, the many remarkable
optical properties of QDs have been combined with the ability to make them increasingly biocompatible and specific to the
target. With this great development, QDs hold particular promise as the next generation of fluorescent probes. This review
describes the developments in functionalizing QDs making use of different bioconjugation and capping approaches. The progress
offered by QDs is evidenced by examples on QD-based biosensing, biolabeling, and delivery of therapeutic agents. In the near
future, QD technology still faces some challenges towards the envisioned broad bioanalytical purposes.
相似文献
53.
54.
Anastasia Doikou Nikos Karaiskos 《Nuclear Physics B》2011,853(2):436-460
We study the classical generalized gln Landau-Lifshitz (L-L) model with special boundary conditions that preserve integrability. We explicitly derive the first non-trivial local integral of motion, which corresponds to the boundary Hamiltonian for the sl2 L-L model. Novel expressions of the modified Lax pairs associated to the integrals of motion are also extracted. The relevant equations of motion with the corresponding boundary conditions are determined. Dynamical integrable boundary conditions are also examined within this spirit. Then the generalized isotropic and anisotropic gln Landau-Lifshitz models are considered, and novel expressions of the boundary Hamiltonians and the relevant equations of motion and boundary conditions are derived. 相似文献
55.
Let $G$ be a bounded Jordan domain in the complex plane. The Bergman polynomials $\{p_n\}_{n=0}^\infty $ of $G$ are the orthonormal polynomials with respect to the area measure over $G$ . They are uniquely defined by the entries of an infinite upper Hessenberg matrix $M$ . This matrix represents the Bergman shift operator of $G$ . The main purpose of the paper is to describe and analyze a close relation between $M$ and the Toeplitz matrix with symbol the normalized conformal map of the exterior of the unit circle onto the complement of $\overline{G}$ . Our results are based on the strong asymptotics of $p_n$ . As an application, we describe and analyze an algorithm for recovering the shape of $G$ from its area moments. 相似文献
56.
57.
Dimitrios Priftis Georgios Sakellariou Jimmy W. Mays Nikos Hadjichristidis 《Journal of polymer science. Part A, Polymer chemistry》2010,48(5):1104-1112
Diels–Alder cycloaddition reactions were used to functionalize multiwalled carbon nanotubes (MWNTs) with 1‐benzocylcobutene‐1′‐phenylethylene (BCB‐PE) or 4‐hydroxyethylbenzocyclobutene (BCB‐EO). The covalent functionalization of the nanotubes with these initiator precursors was verified by FTIR and thermogravimetric analysis (TGA). After appropriate transformations/additions, the functionalized MWNTs were used for surface initiated anionic and ring opening polymerizations of ethylene oxide and ε‐caprolactone (ε‐CL), respectively. The OH‐end groups were transformed to isopropylbromide groups by reaction with 2‐bromoisobutyryl bromide, for subsequent atom transfer radical polymerization of styrene or 2‐dimethylaminoethyl methacrylate to afford the final diblock copolymers. 1H NMR, differential scanning calorimetry (DSC), TGA, and transmission electron microscopy (TEM) were used for the characterization of the nanocomposite materials. TEM images showed the presence of a polymer layer around the MWNTs as well as the dissociation of MWNT bundles. Consequently, this general methodology, employing combinations of different polymerization techniques, increases the diversity of diblocks that can be grafted from MWNTs. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1104–1112, 2010 相似文献
58.
Macrocyclic Gd3+ Complexes with Pendant Crown Ethers Designed for Binding Zwitterionic Neurotransmitters
下载免费PDF全文
![点击此处可从《Chemistry (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Dr. Fatima Oukhatar Hervé Meudal Dr. Céline Landon Prof. Dr. Nikos K. Logothetis Prof. Dr. Carlos Platas‐Iglesias Priv.‐Doz. Dr. Goran Angelovski Dr. Éva Tóth 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(31):11226-11237
A series of Gd3+ complexes exhibiting a relaxometric response to zwitterionic amino acid neurotransmitters was synthesized. The design concept involves ditopic interactions 1) between a positively charged and coordinatively unsaturated Gd3+ chelate and the carboxylate group of the neurotransmitters and 2) between an azacrown ether appended to the chelate and the amino group of the neurotransmitters. The chelates differ in the nature and length of the linker connecting the cyclen‐type macrocycle that binds the Ln3+ ion and the crown ether. The complexes are monohydrated, but they exhibit high proton relaxivities (up to 7.7 mM ?1 s?1 at 60 MHz, 310 K) due to slow molecular tumbling. The formation of ternary complexes with neurotransmitters was monitored by 1H relaxometric titrations of the Gd3+ complexes and by luminescence measurements on the Eu3+ and Tb3+ analogues at pH 7.4. The remarkable relaxivity decrease (≈80 %) observed on neurotransmitter binding is related to the decrease in the hydration number, as evidenced by luminescence lifetime measurements on the Eu3+ complexes. These complexes show affinity for amino acid neurotransmitters in the millimolar range, which can be suited to imaging concentrations of synaptically released neurotransmitters. They display good selectivity over non‐amino acid neurotransmitters (acetylcholine, serotonin, and noradrenaline) and hydrogenphosphate, but selectivity over hydrogencarbonate was not achieved. 相似文献
59.
Nikos?KatzourakisEmail author 《Calculus of Variations and Partial Differential Equations》2017,56(1):15
Consider the supremal functional applied to \(W^{1,\infty }\) maps \(u:\Omega \subseteq \mathbb {R}\longrightarrow \mathbb {R}^N\), \(N\ge 1\). Under certain assumptions on \(\mathscr {L}\), we prove for any given boundary data the existence of a map which is: Our method is based on \(L^p\) approximations and stable a priori partial regularity estimates. For item ii) we utilise the recently proposed by the author notion of \(\mathcal {D}\)-solutions in order to characterise the limit as a generalised solution. Our results are motivated from and apply to Data Assimilation in Meteorology.
相似文献
$$\begin{aligned} E_\infty (u,A) := \Vert \mathscr {L}(\cdot ,u,\mathrm {D}u)\Vert _{L^\infty (A)},\quad A\subseteq \Omega , \end{aligned}$$
(1)
- (i)a vectorial Absolute Minimiser of (1) in the sense of Aronsson,
- (ii)a generalised solution to the ODE system associated to (1) as the analogue of the Euler-Lagrange equations,
- (iii)a limit of minimisers of the respective \(L^p\) functionals as \(p\rightarrow \infty \) for any \(q\ge 1\) in the strong \(W^{1,q}\) topology and
- (iv)partially \(C^2\) on \(\Omega \) off an exceptional compact nowhere dense set.
60.
Dieckmann A Beniken S Lorenz CD Doltsinis NL von Kiedrowski G 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(2):468-480
We have investigated a diastereoselective self‐replicating system based on a cycloaddition of a fulvene derivative and a maleimide using a two‐pronged approach of combining NMR spectroscopy with computational modelling. Two diastereomers are formed with identical rates in the absence of replication. When replication is enabled, one diastereomer takes over the resources as a “selfish” autocatalyst, while exploiting the competitor as a weak “altruist”, resulting in a diastereoselectivity of 16:1. We applied 1D and 2D NMR spectroscopic techniques supported by ab initio chemical shifts as well as ab initio molecular dynamics simulations to study the structure and dynamics of the underlying network. This powerful combination allowed us to decipher the energetic and structural rationale behind the observed behaviour, while static computational methods currently used in the field did not. 相似文献