全文获取类型
收费全文 | 781篇 |
免费 | 19篇 |
国内免费 | 2篇 |
专业分类
化学 | 577篇 |
晶体学 | 6篇 |
力学 | 12篇 |
数学 | 104篇 |
物理学 | 103篇 |
出版年
2023年 | 2篇 |
2022年 | 6篇 |
2021年 | 11篇 |
2020年 | 12篇 |
2019年 | 15篇 |
2018年 | 8篇 |
2017年 | 12篇 |
2016年 | 12篇 |
2015年 | 17篇 |
2014年 | 16篇 |
2013年 | 38篇 |
2012年 | 33篇 |
2011年 | 49篇 |
2010年 | 26篇 |
2009年 | 33篇 |
2008年 | 53篇 |
2007年 | 51篇 |
2006年 | 41篇 |
2005年 | 45篇 |
2004年 | 31篇 |
2003年 | 30篇 |
2002年 | 41篇 |
2001年 | 12篇 |
2000年 | 17篇 |
1999年 | 9篇 |
1998年 | 9篇 |
1997年 | 13篇 |
1996年 | 20篇 |
1995年 | 6篇 |
1994年 | 4篇 |
1993年 | 10篇 |
1992年 | 9篇 |
1991年 | 5篇 |
1990年 | 6篇 |
1989年 | 6篇 |
1988年 | 3篇 |
1987年 | 5篇 |
1986年 | 9篇 |
1985年 | 10篇 |
1984年 | 4篇 |
1983年 | 7篇 |
1982年 | 7篇 |
1981年 | 9篇 |
1980年 | 8篇 |
1978年 | 6篇 |
1977年 | 7篇 |
1976年 | 7篇 |
1973年 | 5篇 |
1939年 | 1篇 |
1937年 | 1篇 |
排序方式: 共有802条查询结果,搜索用时 546 毫秒
81.
Dr. Christiane Lang Sebastian Bestgen Dr. Alexander Welle Rouven Müller Prof. Peter W. Roesky Prof. Christopher Barner‐Kowollik 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(42):14728-14731
A platform technology for the creation of spatially resolved surfaces encoded with a monolayer consisting of different metal complexes was developed. The concept entails the light‐triggered activation of a self‐ assembled monolayer (SAM) of UV‐labile anchors, that is, phenacylsulfides, and the subsequent cycloaddition of selected diene‐functionalized metal complexes at defined areas on the surface. The synthesis and characterization of the metal complexes for the UV‐light assisted anchoring on the surface and a detailed study of a short‐chain oligomer model system in solution confirm the high efficiency of the photoreaction. The hybrid materials obtained by this concept can potentially be utilized for the design of highly valuable catalytic or (opto‐)electronic devices. 相似文献
82.
Marius Durea Radu Strugariu Christiane Tammer 《Journal of Optimization Theory and Applications》2017,175(3):738-763
The aim of this paper is to address new approaches, in separate ways, to necessary and, respectively, sufficient optimality conditions in constrained vector optimization. In this respect, for the necessary optimality conditions that we derive, we use a kind of vectorial penalization technique, while for the sufficient optimality conditions we make use of an appropriate scalarization method. In both cases, the approaches couple a basic technique (of penalization or scalarization, respectively) with several results in variational analysis and optimization obtained by the authors in the last years. These combinations allow us to arrive to optimality conditions which are, in terms of assumptions made, new. 相似文献
83.
84.
Ergot alkaloids are toxins and important pharmaceuticals which are produced biotechnologically on an industrial scale. They have been identi?ed in two orders of fungi and three families of higher plants. The most important producers are fungi of the genera Claviceps, Penicillium and Aspergillus (all belonging to the Ascomycota). Chemically, ergot alkaloids are characterised by the presence of a tetracyclic ergoline ring, and can be divided into three classes according to their structural features, i.e. amide- or peptide-like amide derivatives of D-lysergic acid and the clavine alkaloids. Signi?cant progress has been achieved on the molecular biological and biochemical investigations of ergot alkaloid biosynthesis in the last decade. By gene cloning and genome mining, gene clusters for ergot alkaloid biosynthesis have been identi?ed in at least 8 different ascomycete species. Functions of most structure genes have been assigned to reaction steps in the biosynthesis of ergot alkaloids by gene inactivation experiments or biochemical characterisation of the overproduced proteins. 相似文献
85.
The label-free time-resolved reflectometric interference spectroscopy has been used to study the interaction of the human
estrogen receptor alpha (ERa) and different types of ligands. Different possible sensor surface coatings including various
estrogen derivatives were evaluated for their suitability for detection of ERa. The determination of the kinetic and thermodynamic
constants was carried out for the interaction in the heterogeneous phase as well as for the interaction in homogeneous phase.
In addition, the affinity of 11 ligands ranging from natural hormones and pharmaceuticals to endocrine disrupting chemicals
(EDCs) has been determined with this label-free assay format. 相似文献
86.
Christiane Kraus 《Constructive Approximation》2011,33(2):191-217
The aim of this paper is to extend the classical maximal convergence theory of Bernstein and Walsh for holomorphic functions
in the complex plane to real analytic functions in ℝ
N
. In particular, we investigate the polynomial approximation behavior for functions F:L→ℂ, L={(Re z,Im z):z∈K}, of the structure F=g[`(h)]F=g\overline{h}, where g and h are holomorphic in a neighborhood of a compact set K⊂ℂ
N
. To this end the maximal convergence number ρ(S
c
,f) for continuous functions f defined on a compact set S
c
⊂ℂ
N
is connected to a maximal convergence number ρ(S
r
,F) for continuous functions F defined on a compact set S
r
⊂ℝ
N
. We prove that ρ(L,F)=min {ρ(K,h)),ρ(K,g)} for functions F=g[`(h)]F=g\overline{h} if K is either a closed Euclidean ball or a closed polydisc. Furthermore, we show that min {ρ(K,h)),ρ(K,g)}≤ρ(L,F) if K is regular in the sense of pluripotential theory and equality does not hold in general. Our results are based on the theory
of the pluricomplex Green’s function with pole at infinity and Lundin’s formula for Siciak’s extremal function Φ. A properly chosen transformation of Joukowski type plays an important role. 相似文献
87.
Raoul Normand Lorenzo Zambotti 《Annales de l'Institut Henri Poincaré (C) Analyse Non Linéaire》2011,28(2):189
We prove well-posedness of global solutions for a class of coagulation equations which exhibit the gelation phase transition. To this end, we solve an associated partial differential equation involving the generating functions before and after the phase transition. Applications include the classical Smoluchowski and Flory equations with multiplicative coagulation rate and the recently introduced symmetric model with limited aggregations. For the latter, we compute the limiting concentrations and we relate them to random graph models. 相似文献
88.
Oil droplet size determination in complex flavor delivery systems by diffusion NMR spectroscopy 总被引:1,自引:0,他引:1
Droplet size distribution of flavor oils in two different solid flavor delivery systems were determined with pulsed field gradient NMR spectroscopy: yeast encapsulation system, a spray dried flavor encapsulation system based on empty yeast cells, and glassy encapsulation system, an extruded solid water soluble carbohydrate delivery system. The oil droplet sizes are limited by the yeast cell walls in the yeast encapsulation system and the size distribution is unimodal according to images from transmission electron microscopy. The droplet size determination with diffusion NMR is based on the Murday and Cotts theory of restricted diffusion of liquids in geometrical confinements. Good fits of the diffusion data could be obtained by applying a unimodal, log-normal size distribution model and average droplet sizes of about 2 μm were found that correspond approximately to the inner diameter of the yeast cells. Scanning electron microscopy images showed a multimodal droplet size distribution in the glassy extruded delivery systems. To fit the NMR data a bimodal log-normal distribution function with five independent fitting parameters was implemented that yielded consistent and robust results. The two size populations were found in the micron and sub-micron range, respectively. The method was sufficiently accurate to depict variation of droplet size distributions in glassy encapsulation systems of different formulation. 相似文献
89.
B. Normand 《Contemporary Physics》2013,54(4):533-552
This article discusses at a qualitative level a number of issues at the forefront of current understanding and developments in frustrated quantum magnetism. The focal point of the presentation is the spin liquid, which is introduced in terms of (un)broken spin and lattice symmetries. An overview of the full spectrum of research activity in the field is obtained by considering selected examples from experimental approaches to realising spin-liquid states, from theoretical efforts which seek both to classify spin liquids according to their physical properties and to broaden the search for spin-liquid behaviour, and from numerical techniques which offer the prospect of qualitatively new insight into frustrated spin systems. 相似文献