全文获取类型
收费全文 | 5670篇 |
免费 | 262篇 |
国内免费 | 32篇 |
专业分类
化学 | 3875篇 |
晶体学 | 19篇 |
力学 | 205篇 |
数学 | 1021篇 |
物理学 | 844篇 |
出版年
2023年 | 22篇 |
2021年 | 50篇 |
2020年 | 65篇 |
2019年 | 80篇 |
2018年 | 85篇 |
2017年 | 79篇 |
2016年 | 152篇 |
2015年 | 141篇 |
2014年 | 169篇 |
2013年 | 257篇 |
2012年 | 326篇 |
2011年 | 369篇 |
2010年 | 233篇 |
2009年 | 231篇 |
2008年 | 331篇 |
2007年 | 328篇 |
2006年 | 336篇 |
2005年 | 308篇 |
2004年 | 261篇 |
2003年 | 235篇 |
2002年 | 202篇 |
2001年 | 64篇 |
2000年 | 57篇 |
1999年 | 35篇 |
1998年 | 36篇 |
1997年 | 57篇 |
1996年 | 65篇 |
1995年 | 50篇 |
1994年 | 62篇 |
1993年 | 49篇 |
1992年 | 47篇 |
1991年 | 56篇 |
1990年 | 45篇 |
1989年 | 44篇 |
1988年 | 39篇 |
1987年 | 42篇 |
1986年 | 36篇 |
1985年 | 80篇 |
1984年 | 82篇 |
1983年 | 48篇 |
1982年 | 85篇 |
1981年 | 53篇 |
1980年 | 77篇 |
1979年 | 55篇 |
1978年 | 75篇 |
1977年 | 56篇 |
1976年 | 56篇 |
1975年 | 42篇 |
1974年 | 44篇 |
1973年 | 33篇 |
排序方式: 共有5964条查询结果,搜索用时 93 毫秒
81.
82.
Discrete and continuous non-intersecting random processes have given rise to critical “infinite-dimensional diffusions”, like the Airy process, the Pearcey process and variations thereof. It has been known that domino tilings of very large Aztec diamonds lead macroscopically to a disordered region within an inscribed ellipse (arctic circle in the homogeneous case), and a regular brick-like region outside the ellipse. The fluctuations near the ellipse, appropriately magnified and away from the boundary of the Aztec diamond, form an Airy process, run with time tangential to the boundary. 相似文献
83.
84.
Insertion Reactions of Neutral Phosphidozirconocene Complexes as a Convenient Entry into Frustrated Lewis Pair Territory 下载免费PDF全文
Dr. Adrien T. Normand Dr. Gerald Kehr Prof. Pierre Le Gendre Prof. Gerhard Erker 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(12):4285-4293
Neutral phosphidozirconocene complexes [Cp2Zr(PR2)Me] (Cp=cyclopentadienyl; 1a : R=cyclohexyl (Cy); 1b : R=mesityl (Mes); 1c : R=tBu) undergo insertion into the Zr?P bond by non‐enolisable carbonyl building blocks (O=CR′R′′), such as benzophenone, aldehydes, paraformaldehyde or CO2, to give [Cp2Zr(OCR′R′′PR2)Me] ( 3 – 7 ). Depending on the steric bulk around P, complexes 3 – 7 react with B(C6F5)3 to give O‐bridged cationic zirconocene dimers that display typical frustrated Lewis pair (FLP)/ambiphilic ligand behaviour. Thus, the reaction of {[Cp2Zr(μ‐OCHPhPCy2)][MeB(C6F5)3]}2 ( 10a ) with chalcone results in 1,4 addition of the Zr+/P FLP, whereas the reaction of {[Cp2Zr(μ‐OCHFcPCy2)][MeB(C6F5)3]}2 ( 11a ; Fc=(C5H4)CpFe) with [Pd(η3‐C3H5)Cl]2 yields the unique Zr?Fe?Pd trimetallic complex 13a , which has been characterised by XRD analysis. 相似文献
85.
Pierre Mounoud 《Monatshefte für Mathematik》2015,176(4):603-606
86.
Naphthalimide‐phthalimide derivative based photoinitiating systems for polymerization reactions under blue lights 下载免费PDF全文
Pu Xiao Frédéric Dumur Jing Zhang Bernadette Graff Didier Gigmes Jean Pierre Fouassier Jacques Lalevée 《Journal of polymer science. Part A, Polymer chemistry》2015,53(5):665-674
Naphthalimide‐phthalimide derivatives (NDPDs) have been synthesized and combined with an iodonium salt, N‐vinylcarbazole, amine or 2,4,6‐tris(trichloromethyl)‐1,3,5‐triazine to produce reactive species (i.e., radicals and cations). These generated reactive species are capable of initiating the cationic polymerization of epoxides and/or the radical polymerization of acrylates upon exposure to very soft polychromatic visible lights or blue lights. Compared with the well‐known camphorquinone based systems used as references, the novel NDPD based combinations employed here demonstrate clearly higher efficiencies for the cationic polymerization of epoxides under air as well as the radical polymerization of acrylates. Remarkably, one of the NDPDs (i.e., NDPD2) based systems is characterized by an outstanding reactivity. The structure/reactivity/efficiency relationships of the investigated NDPDs were studied by fluorescence, cyclic voltammetry, laser flash photolysis, electron spin resonance spin trapping, and steady state photolysis techniques. The key parameters for their reactivity are provided. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 665–674 相似文献
87.
Mira Abdallah Diego Magaldi Akram Hijazi Bernadette Graff Frdric Dumur Jean‐Pierre Fouassier Thanh‐Tun Bui Fabrice Goubard Jacques Laleve 《Journal of polymer science. Part A, Polymer chemistry》2019,57(20):2081-2092
In this article, new compounds based on the carbazole scaffold (DMs = DM1 and DM2, constituted by a carbazole unit connected on positions 3 and 6 to a two 4,4′‐dimethoxydiphenylamine groups and differing by the substituent present on the nitrogen heteroatom of the carbazole core) were synthesized and proposed as high‐performance visible light photoinitiators/photosensitizers for both the free‐radical polymerization of methacrylates and the cationic polymerization of epoxides upon visible light exposure using LED@405 nm. Remarkably, DM2 leads to higher final conversions than DM1. In order to study the photophysical and photochemical properties of the carbazole derivatives, different parameters were taken into account such as the light absorption, the steady‐state photolysis, and the fluorescence spectroscopy. Using different techniques such as fluorescence quenching, redox behavior, and cyclic voltammetry, we are able to discuss the photosensitization/photoinitiation reactions providing a full coherent picture of the involved chemical mechanisms. The photosensitization of the carbazole derivatives occurred predominantly via singlet excited states at the rate of the diffusion limit. Upon exposure to laser diode at 405 nm, DMs show high performance in initiating systems for 3D resins. Remarkably, DM2 can also be used in photocomposite synthesis using light‐emitting diode conveyor. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 2081–2092 相似文献
88.
89.
90.