全文获取类型
收费全文 | 2551篇 |
免费 | 42篇 |
国内免费 | 3篇 |
专业分类
化学 | 1897篇 |
晶体学 | 4篇 |
力学 | 14篇 |
数学 | 313篇 |
物理学 | 368篇 |
出版年
2023年 | 13篇 |
2020年 | 13篇 |
2019年 | 18篇 |
2018年 | 14篇 |
2017年 | 15篇 |
2016年 | 38篇 |
2015年 | 50篇 |
2014年 | 52篇 |
2013年 | 136篇 |
2012年 | 158篇 |
2011年 | 166篇 |
2010年 | 80篇 |
2009年 | 66篇 |
2008年 | 173篇 |
2007年 | 170篇 |
2006年 | 189篇 |
2005年 | 165篇 |
2004年 | 134篇 |
2003年 | 95篇 |
2002年 | 74篇 |
2001年 | 69篇 |
2000年 | 81篇 |
1999年 | 27篇 |
1998年 | 15篇 |
1997年 | 26篇 |
1996年 | 32篇 |
1995年 | 26篇 |
1994年 | 25篇 |
1993年 | 18篇 |
1992年 | 25篇 |
1991年 | 18篇 |
1990年 | 22篇 |
1989年 | 10篇 |
1988年 | 22篇 |
1987年 | 12篇 |
1986年 | 21篇 |
1985年 | 29篇 |
1984年 | 16篇 |
1983年 | 20篇 |
1982年 | 17篇 |
1981年 | 14篇 |
1980年 | 22篇 |
1979年 | 18篇 |
1978年 | 14篇 |
1977年 | 14篇 |
1976年 | 16篇 |
1974年 | 19篇 |
1973年 | 15篇 |
1972年 | 9篇 |
1971年 | 10篇 |
排序方式: 共有2596条查询结果,搜索用时 31 毫秒
1.
2.
Synthesis,Electronic Properties and WOLED Devices of Planar Phosphorus‐Containing Polycyclic Aromatic Hydrocarbons 下载免费PDF全文
Dr. François Riobé Rózsa Szűcs Dr. Pierre‐Antoine Bouit Dr. Denis Tondelier Bernard Geffroy Fátima Aparicio Julia Buendía Prof. Luis Sánchez Prof. Régis Réau Prof. László Nyulászi Prof. Muriel Hissler 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(17):6547-6556
We describe the synthesis and the physical properties of polyaromatic hydrocarbons (PAHs) containing a phosphorus atom at the edge. In particular, the impact of the successive addition of aromatic rings on the electronic properties was investigated by experimental (UV/Vis absorption, fluorescence, cyclic voltammetry) and theoretical studies (DFT). The physical properties recorded in solution and in the solid state showed that the P‐containing PAHs exhibit properties expected for an emitter in white organic light‐emitting diodes (WOLEDs). 相似文献
3.
4.
Unsteady motion in single-line flow-injection systems consisting of n tubular elements with valve or hydrodynamic injection is studied theoretically. A formula for the duration of the initial period of unsteady flow is derived. This initial period is much shorter than the mean residence time of the analyte in practical systems. It can therefore be neglected in mathematical modelling of such systems. Experimental data obtained with single-line systems with valve and hydrodynamic injection confirmed the validity of the theoretical equations. 相似文献
5.
The function lattice, or generalized Boolean algebra, is the set of ℓ-tuples with the ith coordinate an integer between 0 and a bound ni. Two ℓ-tuples t-intersect if they have at least t common nonzero coordinates. We prove a Hilton–Milner type theorem for systems of t-intersecting ℓ-tuples.Received September 29, 2004 相似文献
6.
Marcel Erné 《Order》1991,8(2):159-173
We introduce a special type of order-preserving maps between quasiordered sets, the so-called cut-stable maps. These form the largest morphism class such that the corresponding category of quasiordered sets contains the category of complete lattices and complete homomorphisms as a full reflective subcategory, the reflector being given by the Dedekind-MacNeille completion (alias normal completion or completion by cuts). Suitable restriction of the object class leads to the category of separated quasiordered sets and its full reflective subcategory of completely distributive lattices. Similar reflections are obtained for continuous lattices, algebraic lattices, etc. 相似文献
7.
Ildikó Mohammed-Ziegler Ferenc Billes 《Journal of inclusion phenomena and macrocyclic chemistry》2007,58(1-2):19-42
This review summarizes different applications of optical spectroscopic methods in calixarene chemistry including UV/Vis spectrometry,
vibrational spectroscopic techniques (FTIR and Raman spectroscopy), luminescence spectroscopy (including fluorescence and
phosphorescence), ellipsometry and various optical microscopic methods. Moreover, the results of theoretical studies (AM1,
PM3, DFT, ab initio, etc.) are summarized based on selected papers in the field of conformational studies, thermodynamics and complexation features.
About 300 references are processed systematically from the results reported mainly in the recent years with emphasis on the
potential of practical application of these molecules. 相似文献
8.
A quick sample preparation method was used for the determination of sulphur and trace metals in oil and oily products by the ICP with a minitorch. Stable aqueous emulsions of oils and oil products were made by using two kinds of emulsifiers (one with low sulphur content, the other sulfonated). Aqueous standard solutions can be used for the preparation of calibration solutions. The contents of S, Al, Cr, Cu, Fe, Mg, Ni and Pb in aqueous emulsions were determined and the results were in good agreement with the composition of oil standard solutions used for control analysis procedure. 相似文献
9.
Jenó Szigeti 《Order》1990,7(1):77-81
Given a linearly ordered set (A,
R
) and an R-monotone function f: AA, we give a necessary and sufficient condition on A, f,
R
, involving generating sets and forbidden subalgebras, for
R
to be a well-ordering.Partially supported by Hungarian National Foundation for Scientific Research Grant nr. 1813. 相似文献
10.
Marcel Erné 《Algebra Universalis》1988,25(1):290-321
By a result of Pigozzi and Kogalovskii, every algebraic latticeL having a completely join —irreducible top element can be represented as the lattice L() of equational theories extending some fixed theory . Conversely, strengthening a recent result due to Lampe, we show that such a representationL=L() forcesL to satisfy the following condition: if the top element ofL is the join of a nonempty subsetB ofL then there are elementsb..., B such thata=(... (((b1 a) b2) a) ... bn) a for alla L. In presence of modularity, this equation reduces to the identitya=(a b1) ... (a bn). Motivated by these facts, we study several weak forms of distributive laws in arbitrary lattices and related types of prime elements. The main tool for applications to universal algebra is a generalized version of Lampe's Zipper Lemma.Presented by Ralph Freese. 相似文献