全文获取类型
收费全文 | 1568篇 |
免费 | 32篇 |
国内免费 | 12篇 |
专业分类
化学 | 1135篇 |
晶体学 | 44篇 |
力学 | 38篇 |
数学 | 105篇 |
物理学 | 290篇 |
出版年
2023年 | 7篇 |
2022年 | 7篇 |
2021年 | 12篇 |
2020年 | 22篇 |
2019年 | 19篇 |
2018年 | 15篇 |
2017年 | 22篇 |
2016年 | 28篇 |
2015年 | 21篇 |
2014年 | 35篇 |
2013年 | 70篇 |
2012年 | 75篇 |
2011年 | 117篇 |
2010年 | 53篇 |
2009年 | 57篇 |
2008年 | 126篇 |
2007年 | 102篇 |
2006年 | 101篇 |
2005年 | 86篇 |
2004年 | 66篇 |
2003年 | 77篇 |
2002年 | 72篇 |
2001年 | 35篇 |
2000年 | 23篇 |
1999年 | 20篇 |
1998年 | 18篇 |
1997年 | 11篇 |
1996年 | 16篇 |
1995年 | 9篇 |
1994年 | 21篇 |
1993年 | 15篇 |
1992年 | 9篇 |
1991年 | 17篇 |
1990年 | 6篇 |
1989年 | 15篇 |
1987年 | 7篇 |
1986年 | 18篇 |
1985年 | 25篇 |
1984年 | 12篇 |
1983年 | 13篇 |
1982年 | 16篇 |
1981年 | 13篇 |
1980年 | 13篇 |
1979年 | 8篇 |
1978年 | 13篇 |
1977年 | 12篇 |
1976年 | 18篇 |
1975年 | 9篇 |
1974年 | 6篇 |
1973年 | 5篇 |
排序方式: 共有1612条查询结果,搜索用时 0 毫秒
1.
The existence of a Nash equilibrium in the undiscounted repeated two-person game of incomplete information on one side is
established. The proof depends on a new topological result resembling in some respect the Borsuk-Ulam theorem. 相似文献
2.
3.
4.
5.
Satoshi Ito Kazuya Koizumi Katsuhiko Fukuda Naohiro Kameta Tsukasa Ikeda Toru Oba Kazuhisa Hiratani 《Tetrahedron letters》2006,47(48):8563-8566
A new series of BINOL-based macrocycles with two phenolic protons have been synthesized via oxidative coupling reaction using CuCl(OH)-TMEDA. 相似文献
6.
Abou El-Nasr EA Fujii A Yahagi T Ebata T Mikami N 《The journal of physical chemistry. A》2005,109(11):2498-2504
Geometric structures and excited-state proton dislocation of size-selected salicylic acid clusters (salicylic acid and 5-methoxysalicylic acid) with water were studied by using laser spectroscopic techniques. Fluorescence excitation, dispersed fluorescence, and infrared (IR) spectra of those clusters in supersonic jets were examined for both the electronic ground (S0) and first excited (S1) states. The geometric structures of the clusters were determined on the basis of the IR spectra of the OH stretch region with the help of quantum chemical calculations. The hydroxyl group of the water moiety in the clusters forms a ring involving the carboxylic group of the salicylic acid moiety. The IR spectra in S0 show that the intramolecular hydrogen bond in the salicylic acid moiety is still held upon cluster formation, but the phenolic OH stretch band intensity is remarkably weaken in the clusters. The IR spectra in the S1 state and dispersed fluorescence spectra indicated that the intramolecular excited state proton dislocation is hardly affected by the microsolvation with water, in contrast with the strong suppression of the dislocation in the self-solvation. 相似文献
7.
Novel synthesis of heterocyclic spirans by tandem cycloaddition to sulfur-containing heterocumulenes
Yoshiki Ohshiro Hitoshi Nanimoto Hiroyuki Tanaka Mitsuo Komatsu Toshio Agawa Noritake Yasuoka Yasushi Kai Nobutami Kasai 《Tetrahedron letters》1985,26(25):3015-3018
Novel Ni(C0)4-promoted tandem cycloadditions of diphenylcyclo- propenone to isothiocyanates and to CS2 were found to provide new heterocyclic spirans, pyrroline-2-one-5-spiro-5′-thiolene-4′-ones and a thiolene-2-one-5-spiro-5′-thiolene-4′-one, respectively, in moderate yields. 相似文献
8.
Three novel diepoxy tetrahydrochromones, oxidoagarochromones A (1), B (2), and C (3), were isolated from agarwood artificially produced by intentional wounding of Aquilaria crassna. Inductive production of these compounds was also confirmed at the early stage of wounding in A. sinensis and A. crassna. These diepoxy tetrahydrochromones would play an important role in understanding the biosynthesis of chromone derivatives in agarwood. 相似文献
9.
Komatsu H Iwasawa N Citterio D Suzuki Y Kubota T Tokuno K Kitamura Y Oka K Suzuki K 《Journal of the American Chemical Society》2004,126(50):16353-16360
The role of intracellular magnesium ions is of high interest in the fields of pharmacology and cellular biology. To accomplish the dynamic and three-dimensional imaging of intracellular Mg2+, there is a strong desire for the development of optimized Mg2+ fluorescent probes. In this paper we describe the design, synthesis, and cellular application of the three novel Mg2+ fluorescent probes KMG-101, -103, and -104. The compounds of this series feature a charged beta-diketone as a binding site specific for Mg2+ and a fluorescein residue as the fluorophore that can be excited with an Ar+ laser such as is widely used in confocal scanning microscopy. This molecular design leads to an intensive off-on-type fluorescent response toward Mg2+ ions. The two fluorescent probes KMG-103 and -104 showed suitable dissociation constants (Kd,Mg2+ = 2 mM) and nearly a 10-fold fluorescence enhancement over the intracellular magnesium ion concentration range (0.1-6 mM), allowing high-contrast, sensitive, and selective Mg2+ measurements. For intracellular applications, the membrane-permeable probe KMG-104AM was synthesized and successfully incorporated into PC12 cells. Upon application of the mitochondria uncoupler FCCP to the probe-incorporated cells, the resulting increase in the free magnesium ion concentration could be followed over time. By using a confocal microscope, the intracellular 3D magnesium ion concentration distributions were satisfactorily observed. 相似文献
10.
Yoshimoto S Ohashi F Ohnishi Y Nonami T 《Chemical communications (Cambridge, England)》2004,(17):1924-1925
Nanocomposites consisting of conducting polyaniline and clay minerals were successfully synthesized from mechanochemically intercalated anilinium fluoride; the nanocomposites prepared by the mechanochemical intercalation method contained much more polyaniline in the clay layers than those prepared by a conventional solution method. 相似文献