全文获取类型
收费全文 | 965篇 |
免费 | 42篇 |
国内免费 | 7篇 |
专业分类
化学 | 519篇 |
晶体学 | 5篇 |
力学 | 55篇 |
数学 | 282篇 |
物理学 | 153篇 |
出版年
2023年 | 12篇 |
2022年 | 20篇 |
2021年 | 30篇 |
2020年 | 27篇 |
2019年 | 22篇 |
2018年 | 15篇 |
2017年 | 13篇 |
2016年 | 54篇 |
2015年 | 39篇 |
2014年 | 48篇 |
2013年 | 76篇 |
2012年 | 88篇 |
2011年 | 63篇 |
2010年 | 45篇 |
2009年 | 39篇 |
2008年 | 55篇 |
2007年 | 44篇 |
2006年 | 44篇 |
2005年 | 21篇 |
2004年 | 32篇 |
2003年 | 40篇 |
2002年 | 20篇 |
2001年 | 13篇 |
2000年 | 11篇 |
1999年 | 13篇 |
1998年 | 11篇 |
1997年 | 8篇 |
1996年 | 4篇 |
1995年 | 5篇 |
1994年 | 5篇 |
1993年 | 3篇 |
1992年 | 7篇 |
1991年 | 6篇 |
1989年 | 5篇 |
1988年 | 4篇 |
1987年 | 4篇 |
1986年 | 3篇 |
1985年 | 8篇 |
1984年 | 10篇 |
1983年 | 3篇 |
1982年 | 6篇 |
1981年 | 6篇 |
1978年 | 2篇 |
1977年 | 3篇 |
1976年 | 3篇 |
1969年 | 2篇 |
1924年 | 2篇 |
1911年 | 2篇 |
1897年 | 2篇 |
1893年 | 2篇 |
排序方式: 共有1014条查询结果,搜索用时 0 毫秒
61.
62.
Set-Valued and Variational Analysis - We study the stability of solutions to ${H_{0}^{1}}$ -elliptic variational inequalities of the second kind that contain a non-differentiable Nemytskii... 相似文献
63.
Dr. Rüdiger W. Seidel Richard Goddard Constantin Hoch Iris M. Oppel 《无机化学与普通化学杂志》2011,637(11):1545-1554
Attempts to crystal engineer metallosupramolecularcomplexes from Cu(phen)2+ building blocks and the prototypical,rod‐like, exo‐bidentate ligand 4,4′‐bipyridine (4,4′‐bipy) by layering techniques are described. Reactions of Cu(phen)2+ (phen = 1,10‐phenanthroline) with 4,4′‐bipy in the presence of NO3– counterions yielded two distinct, discrete, dinuclear, Ci symmetric, dumbbell‐typecomplexes, [{Cu(NO3)2(phen)}2(4,4′‐bipy)] ( 1 ) and [{Cu(NO3)(phen)(H2O)}2(4,4′‐bipy)](NO3)2 ( 2 ), depending upon the mixture of solvents used for crystallization. In compound 1 , a mono‐ and a bidentate nitrato group coordinate to Cu2+, whereas in 2 the monodentate nitrato groups are replaced by aqua ligands, which introduce additional hydrogen‐bond donor functionality to the molecule. The crystal structure of 1 was determined by single‐crystal X‐ray analysis at 296 and 110 K. Upon cooling, a disorder‐order transition occurs, with retention of the space group symmetry. The crystal structure of 2 at room temperature was reported previously [Z.‐X. Du, J.‐X. Li, Acta Cryst. 2007 , E63, m2282]. We have redetermined the crystal structure of 2 at 100 K. A phase transition is not observed for 2 , but the low temperature single‐crystal structure determination is of significantly higher precision than the room temperature study. Both 1 and 2 are obtained phase‐pure, as proven by powder X‐ray diffraction of the bulk materials. Crystals of [Cu(phen)(CF3SO3)2(4,4′‐bipy) · 0.5H2O]n ( 3 ), a one‐dimensional coordination polymer, were obtained from [Cu(CF3SO3)2(phen)(H2O)2] and 4,4′‐bipy. In 3 , Cu(phen)2+ corner units are joined by 4,4′‐bipy via the two vacant cis sites to form polymeric zig‐zag chains, which are tightly packed in the crystal. Compounds 1 – 3 were further studied by infrared spectroscopy. 相似文献
64.
Functionalization of Intramolecular Frustrated Lewis Pairs by 1,1‐Carboboration with Conjugated Enynes 下载免费PDF全文
Dr. Andreas Feldmann Dr. Gerald Kehr Dr. Constantin G. Daniliuc Dr. Christian Mück‐Lichtenfeld Prof. Dr. Gerhard Erker 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(35):12456-12464
The vicinal P/B frustrated Lewis pair (FLP) Mes2PCH2CH2B(C6F5)2 undergoes 1,1‐carboboration reactions with the Me3Si‐substituted enynes to give ring‐enlarged functionalized C3‐bridged P/B FLPs. These serve as active FLPs in the activation of dihydrogen to give the respective zwitterionic [P]H+/[B]H? products. One such product shows activity as a metal‐free catalyst for the hydrogenation of enamines or a bulky imine. The ring‐enlarged FLPs contain dienylborane functionalities that undergo “bora‐Nazarov”‐type ring‐closing rearrangements upon photolysis. A DFT study had shown that the dienylborane cyclization of such systems itself is endothermic, but a subsequent C6F5 migration is very favorable. Furthermore, substituted 2,5‐dihydroborole products are derived from cyclization and C6F5 migration from the photolysis reaction. In the case of the six‐membered annulation product, a subsequent stereoisomerization reaction takes place and the resultant compound undergoes a P/B FLP 1,2‐addition reaction with a terminal alkyne with rearrangement. 相似文献
65.
Afanasiev S Aidala C Ajitanand NN Akiba Y Alexander J Al-Jamel A Aoki K Aphecetche L Armendariz R Aronson SH Averbeck R Awes TC Azmoun B Babintsev V Baldisseri A Barish KN Barnes PD Bassalleck B Bathe S Batsouli S Baublis V Bauer F Bazilevsky A Belikov S Bennett R Berdnikov Y Bjorndal MT Boissevain JG Borel H Boyle K Brooks ML Brown DS Bucher D Buesching H Bumazhnov V Bunce G Burward-Hoy JM Butsyk S Campbell S Chai JS Chernichenko S Chiba J Chi CY Chiu M Choi IJ Chujo T Chung P Cianciolo V 《Physical review letters》2008,100(23):232301
A three-dimensional correlation function obtained from midrapidity, low p(T), pion pairs in central Au+Au collisions at sqrt[s(NN)]=200 GeV is studied. The extracted model-independent source function indicates a long range tail in the directions of the pion pair transverse momentum (out) and the beam (long). A proper breakup time tau(0) ~ 9 fm/c and a mean proper emission duration Delta tau ~ 2 fm/c, leading to sizable emission time differences ({|Delta t(LCM)|} approximately 12 fm/c), are required to allow models to be successfully matched to these tails. The model comparisons also suggest an outside-in "burning" of the emission source reminiscent of many hydrodynamical models. 相似文献
66.
67.
Paul Constantin 《Acta Physica Hungarica A》2006,27(2-3):251-254
We present preliminary results from intermediate p T(1–5 GeV/c) di-hadron azimuthal correlations induced by hadronic di-jets produced in AuAu collisions at √s NN =200 GeV. The near-side (Δ?~0) has a typical singlepeaked structure which broadens with the centrality of the collision. A qualitatively new phenomenon shows up in the shape of the away-side (Δ?~π): it has a symmetric, double-peaked structure in central and mid-central collisions. 相似文献
68.
In this paper we derive a probabilistic representation of the deterministic three‐dimensional Navier‐Stokes equations based on stochastic Lagrangian paths. The particle trajectories obey SDEs driven by a uniform Wiener process; the inviscid Weber formula for the Euler equations of ideal fluids is used to recover the velocity field. This method admits a self‐contained proof of local existence for the nonlinear stochastic system and can be extended to formulate stochastic representations of related hydrodynamic‐type equations, including viscous Burgers equations and Lagrangian‐averaged Navier‐Stokes alpha models. © 2007 Wiley Periodicals, Inc. 相似文献
69.
The unsteady flow of a viscoelastic fluid with the fractional Maxwell model between two side walls perpendicular to a plate is investigated. Exact solutions for the velocity field are established by means of the Fourier and Laplace transforms. The similar solutions for Maxwell and Newtonian fluids can be obtained as limiting cases of our results. In the absence of side walls, all solutions that have been determined reduce to those corresponding to the motion over an infinite plate. 相似文献
70.