全文获取类型
收费全文 | 557篇 |
免费 | 10篇 |
国内免费 | 9篇 |
专业分类
化学 | 249篇 |
晶体学 | 1篇 |
力学 | 30篇 |
数学 | 111篇 |
物理学 | 185篇 |
出版年
2022年 | 4篇 |
2021年 | 9篇 |
2020年 | 7篇 |
2019年 | 10篇 |
2018年 | 11篇 |
2017年 | 12篇 |
2016年 | 17篇 |
2015年 | 11篇 |
2014年 | 13篇 |
2013年 | 30篇 |
2012年 | 22篇 |
2011年 | 30篇 |
2010年 | 11篇 |
2009年 | 16篇 |
2008年 | 31篇 |
2007年 | 15篇 |
2006年 | 24篇 |
2005年 | 28篇 |
2004年 | 24篇 |
2003年 | 20篇 |
2002年 | 20篇 |
2001年 | 22篇 |
2000年 | 13篇 |
1999年 | 7篇 |
1998年 | 11篇 |
1997年 | 8篇 |
1996年 | 7篇 |
1995年 | 12篇 |
1994年 | 5篇 |
1993年 | 4篇 |
1992年 | 8篇 |
1991年 | 10篇 |
1990年 | 11篇 |
1989年 | 3篇 |
1988年 | 5篇 |
1985年 | 6篇 |
1984年 | 9篇 |
1982年 | 7篇 |
1981年 | 5篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1977年 | 8篇 |
1976年 | 5篇 |
1975年 | 6篇 |
1974年 | 9篇 |
1973年 | 4篇 |
1971年 | 4篇 |
1970年 | 2篇 |
1968年 | 2篇 |
1967年 | 2篇 |
排序方式: 共有576条查询结果,搜索用时 125 毫秒
101.
A Zero‐Dimensional Organic Seesaw‐Shaped Tin Bromide with Highly Efficient Strongly Stokes‐Shifted Deep‐Red Emission
下载免费PDF全文
![点击此处可从《Angewandte Chemie (International ed. in English)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Chenkun Zhou Dr. Haoran Lin Prof. Hongliang Shi Yu Tian Chongin Pak Prof. Michael Shatruk Yan Zhou Dr. Peter Djurovich Dr. Mao‐Hua Du Prof. Biwu Ma 《Angewandte Chemie (International ed. in English)》2018,57(4):1021-1024
The synthesis and characterization is reported of (C9NH20)2SnBr4, a novel organic metal halide hybrid with a zero‐dimensional (0D) structure, in which individual seesaw‐shaped tin (II) bromide anions (SnBr42?) are co‐crystallized with 1‐butyl‐1‐methylpyrrolidinium cations (C9NH20+). Upon photoexcitation, the bulk crystals exhibit a highly efficient broadband deep‐red emission peaked at 695 nm, with a large Stokes shift of 332 nm and a high quantum efficiency of around 46 %. The unique photophysical properties of this hybrid material are attributed to two major factors: 1) the 0D structure allowing the bulk crystals to exhibit the intrinsic properties of individual SnBr42? species, and 2) the seesaw structure enabling a pronounced excited state structural deformation as confirmed by density functional theory (DFT) calculations. 相似文献
102.
Hong Kyung Pak 《Geometriae Dedicata》1997,66(1):19-25
In Pak (Ann. Global Anal. Geom.13 (1995), 281–288), the notion of -automorphisms of a harmonic Riemannian foliation was extended to a general Riemannian foliation. By applying the characterization obtained in Pak of a -automorphism to be transversal Killing, we here consider the problem that a transversal conformal or projective field is transversal Killing. A special condition, namely B B = 0, is discussed. 相似文献
103.
The internal energy of ions and the timescale play fundamental roles in mass spectrometry. The main objective of this study is to estimate and compare the internal energy distributions of different ions (different nature, degree of freedom 'DOF' and fragmentations) produced in an electrospray source (ESI) of a triple-quadrupole instrument (Quattro I Micromass). These measurements were performed using both the Survival Yield method (as proposed by De Pauw) and the MassKinetics software (kinetic model introduced by Vékey). The internal energy calibration is the preliminary step for ESI and collision-induced dissociation (CID) spectra calculation. meta-Methyl-benzylpyridinium ion and four protonated peptides (YGGFL, LDIFSDF, LDIFSDFR and RLDIFSDF) were produced using an electrospray source. These ions were used as thermometer probe compounds. Cone voltages (V(c)) were linearly correlated with the mean internal energy values () carried by desolvated ions. These mean internal energy values seem to be slightly dependent on the size of the studied ion. ESI mass spectra and CID spectra were then simulated using the MassKinetics software to propose an empirical equation for the mean internal energy () versus cone voltage (V(c)) for different source temperatures (T): < E(int) > = [405 x 10(-6) - 480 x 10(-9) (DOF)] V(c)T + E(therm)(T). In this equation, the E(therm)(T) parameter is the mean internal energy due to the source temperature at 0 V(c). 相似文献
104.
This paper reports the design and optimization of a double-stranded molecular probe for homogeneous detection of specific nucleotide sequences. The probes are labeled with either a fluorophore or a quencher such that the probe hybridization brings the two labels into close proximity, and this diminishes the fluorescence signal in the absence of a target. In the presence of a target, the fluorophore probe is thermodynamically driven to unzip from its hybridized form and bind with the target. An equilibrium analysis, which successfully describes all the major features of the assay without any fitting parameter, is performed to generalize the design of the probe. Several key parameters affecting the performance of the assay are examined. We show that the dynamic range and the signal-to-noise ratio of the assay can be optimized by the probe concentration, the quencher-to-fluorophore ratio, and the probe strand sequence. By proper design of the sequence, the probe discriminates single nucleotide mismatches in a single step without any separation step or measurement of melting profile. 相似文献
105.
106.
We performed ab initio folding simulation for a betabetaalpha peptide BBA5 (PDB code 1T8J) with a modified param99 force field using the generalized Born solvation model (param99MOD5/GBSA). For efficient conformational sampling, we extended a previously developed novel Q-replica exchange molecular dynamics (Q-REMD) into a multiplexed Q-REMD. Starting from a fully extended conformation, we were able to locate the nativelike structure in the global free minimum region at 280 K. The current approach, which combines the more balanced force field with the efficient sampling scheme, demonstrates a clear advantage in direct folding simulation at all-atom level. 相似文献
107.
108.
The distance function \({\varrho(p, q) ({\rm or} d(p, q))}\) of a distance space (general metric space) is not differentiable in general. We investigate such distance spaces over \({\mathbb{R}^n}\), whose distance functions are differentiable like in case of Finsler spaces. These spaces have several good properties, yet they are not Finsler spaces (which are special distance spaces). They are situated between general metric spaces (distance spaces) and Finsler spaces. We will investigate such curves of differentiable distance spaces, which possess the same properties as geodesics do in Finsler spaces. So these curves can be considered as forerunners of Finsler geodesics. They are in greater plenitude than Finsler geodesics, but they become geodesics in a Finsler space. We show some properties of these curves, as well as some relations between differentiable distance spaces and Finsler spaces. We arrive to these curves and to our results by using distance spheres, and using no variational calculus. We often apply direct geometric considerations. 相似文献
109.
Tarasenkov A. N. Vasil´ev V. G. Buzin M. I. Getmanova E. V. Pak G. G. Kramarenko E. Yu. Muzafarov A. M. 《Russian Chemical Bulletin》2016,65(4):1086-1096
Russian Chemical Bulletin - The rheological properties of hyperbranched polycarbosilanes with butyl and decyl terminal groups and their sulfur-containing analogs were compared. The use of various... 相似文献
110.