全文获取类型
收费全文 | 819篇 |
免费 | 32篇 |
国内免费 | 3篇 |
专业分类
化学 | 564篇 |
晶体学 | 13篇 |
力学 | 20篇 |
数学 | 91篇 |
物理学 | 166篇 |
出版年
2023年 | 7篇 |
2022年 | 12篇 |
2021年 | 14篇 |
2020年 | 22篇 |
2019年 | 18篇 |
2018年 | 10篇 |
2017年 | 19篇 |
2016年 | 20篇 |
2015年 | 17篇 |
2014年 | 25篇 |
2013年 | 48篇 |
2012年 | 62篇 |
2011年 | 86篇 |
2010年 | 38篇 |
2009年 | 31篇 |
2008年 | 49篇 |
2007年 | 39篇 |
2006年 | 47篇 |
2005年 | 42篇 |
2004年 | 27篇 |
2003年 | 12篇 |
2002年 | 27篇 |
2001年 | 8篇 |
2000年 | 8篇 |
1999年 | 9篇 |
1998年 | 8篇 |
1996年 | 7篇 |
1995年 | 4篇 |
1994年 | 3篇 |
1993年 | 8篇 |
1992年 | 4篇 |
1991年 | 3篇 |
1990年 | 3篇 |
1989年 | 4篇 |
1988年 | 5篇 |
1985年 | 5篇 |
1984年 | 9篇 |
1982年 | 6篇 |
1981年 | 5篇 |
1980年 | 7篇 |
1979年 | 9篇 |
1978年 | 6篇 |
1977年 | 3篇 |
1976年 | 4篇 |
1975年 | 4篇 |
1974年 | 6篇 |
1973年 | 5篇 |
1943年 | 3篇 |
1883年 | 4篇 |
1862年 | 2篇 |
排序方式: 共有854条查询结果,搜索用时 15 毫秒
51.
In basic medium, dimethyl 3,3'-dithiopropionate generates methyl acrylate, which serves in situ as a source of propionate moiety. This property was applied to the alkylation of indoles and other nitrogen heterocycles leading to a series of 3-(heteroaryl-substituted) propionates. A mechanistic rationale for the generation of acrylate is presented along with supportive experimental data. 相似文献
52.
In a pair of atoms in collision, the polarizability of the system depends on the relative velocity. The mechanism introduced here implies the time dependence of the effective field acting on the partners. The linear term of the expansion with respect to the velocity suggests the existence of an optical activity for a monatomic fluid submitted to a non-uniform flow. 相似文献
53.
Joshua Rokach Yves Girard Yvan Guindon Joseph G. Atkinson Marie Larue Robert N. Young Paul Masson George Holme 《Tetrahedron letters》1980,21(16):1485-1488
The synthesis and biological characteristics of an SRS-like leukotriene are described. 相似文献
54.
55.
Miguel?Escobedo Philippe?Lauren?ot Stéphane?MischlerEmail author 《Communications in Mathematical Physics》2004,246(2):237-267
Existence of global weak solutions to a spatially inhomogeneous kinetic model for coalescing particles is proved, each particle being identified by its mass, momentum and position. The large time convergence to zero is also shown. The cornestone of our analysis is that, for any nonnegative and convex function, the associated Orlicz norm is a Liapunov functional. Existence and asymptotic behaviour then rely on weak and strong compactness methods in L1 in the spirit of the DiPerna-Lions theory for the Boltzmann equation. 相似文献
56.
Bourguet E Baneres JL Girard JP Parello J Vidal JP Lusinchi X Declercq JP 《Organic letters》2001,3(20):3067-3070
[reaction: see text] Photolysis of oxaziridines a or nitrones b provides a convenient synthetic route to fused bicyclic lactams c adequately substituted on both cycles A and B as scaffolds for mimicking conformationally constrained beta-turn peptides as in the tripeptide RGD signaling motif of fibronectin. 相似文献
57.
The following review article provides an overview of oxidopyrylium [5+2] cycloaddition chemistry, with a particular emphasis placed on seminal historical developments and advancements made over the last decade. It is our hope this review serves as a valuable resource to those interested in the oxidopyrylium cycloaddition chemistry, and helps inspire future advancements. 相似文献
58.
We have coupled CIEF with an LIF detector that is based on a post‐column sheath flow cuvette. We employed Chromeo P503 as a fluorogenic reagent to label proteins before analysis. This reagent reacts with the ε‐amine of lysine residues, preserving the cationic nature of the residue; labeled proteins generate extremely sharp peaks in CIEF. A set of four standard proteins generated a linear relationship between migration time and pI. A protein homogenate prepared from a Barrett's esophagus cell line resolved over 100 components in a 40 min separation. Detection limits for Chromeo P503‐labeled β‐lactoglobulin were 5 amol injected into the capillary. Fluorescent impurities present in the ampholytes generated a large background signal that degraded the detection limit by four orders of magnitude compared with other forms of capillary electrophoresis with this detector. 相似文献
59.
Harini Kilambi Sirish K. Reddy Lauren Schneidewind Jeffrey W. Stansbury Christopher N. Bowman 《Journal of polymer science. Part A, Polymer chemistry》2009,47(19):4859-4870
The impact of secondary functionalities on the radical‐vinyl chemistry of monoacrylates characterized by secondary functionalities that dramatically enhance their polymerization rate was elucidated utilizing experimental and computational techniques. Firstly, bulk interactions affecting the acrylate reactivity towards photopolymerization were removed by polymerizing at 5 wt % monomer in 1,4‐dioxane. Following deconvolution of bulk interactions impacting reactivity towards photopolymerization, a linear correlation between average polymerization rates and Michael addition reaction rate constants was observed on a logarithmic scale. This result indicates that the presence of the secondary functionality intramolecularly alters the monomer chemistry in a manner which impacts both of these distinct reaction types in a similar manner. These monomers exhibited reduced activation energies in both Michael addition and photopolymerization reactions as compared to hexyl acrylate. Reduction up to 20 ± 8 kJ mole?1was observed for Michael addition reactions and 12 ± 1 kJ mole?1 for photopolymerization reactions, thereby explaining the higher reactivity of the acrylates characterized by the secondary functionalities. Cyclic voltammetry experiments conducted to investigate the nature of the acrylic double bonds indicated that the rapidly polymerizing acrylates are more readily reduced as compared to traditional acrylates. Further, a distinct monotonic correlation of the irreversible cathodic peak potentials of the (meth)acrylates to photopolymerization and Michael addition reactivity was observed. The computationally estimated acrylic LUMO energies characterized by the secondary functionalities (?2.3 eV to ?2.7 eV) were also found to be lower relative to hexyl acrylate (?2.2 eV). © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4859–4870, 2009 相似文献
60.
Th. Münzel A. Wynter Blyth Kützing und Ch. Girard 《Fresenius' Journal of Analytical Chemistry》1882,21(1):436-438
Ohne Zusammenfassung 相似文献