全文获取类型
收费全文 | 2213篇 |
免费 | 90篇 |
国内免费 | 6篇 |
专业分类
化学 | 1807篇 |
晶体学 | 29篇 |
力学 | 25篇 |
数学 | 95篇 |
物理学 | 353篇 |
出版年
2023年 | 5篇 |
2021年 | 20篇 |
2020年 | 26篇 |
2019年 | 43篇 |
2018年 | 20篇 |
2017年 | 15篇 |
2016年 | 48篇 |
2015年 | 36篇 |
2014年 | 68篇 |
2013年 | 87篇 |
2012年 | 111篇 |
2011年 | 134篇 |
2010年 | 87篇 |
2009年 | 59篇 |
2008年 | 143篇 |
2007年 | 137篇 |
2006年 | 139篇 |
2005年 | 145篇 |
2004年 | 136篇 |
2003年 | 117篇 |
2002年 | 95篇 |
2001年 | 50篇 |
2000年 | 45篇 |
1999年 | 31篇 |
1998年 | 32篇 |
1997年 | 32篇 |
1996年 | 19篇 |
1995年 | 21篇 |
1994年 | 12篇 |
1993年 | 12篇 |
1992年 | 37篇 |
1991年 | 23篇 |
1990年 | 18篇 |
1989年 | 6篇 |
1988年 | 15篇 |
1987年 | 8篇 |
1986年 | 8篇 |
1985年 | 34篇 |
1984年 | 31篇 |
1983年 | 16篇 |
1982年 | 20篇 |
1981年 | 24篇 |
1980年 | 15篇 |
1979年 | 25篇 |
1978年 | 14篇 |
1977年 | 15篇 |
1976年 | 10篇 |
1975年 | 13篇 |
1974年 | 11篇 |
1973年 | 19篇 |
排序方式: 共有2309条查询结果,搜索用时 15 毫秒
11.
We have investigated the transient characteristics of discrete Raman Amplifiers and found that the response time caused by gain saturation is dependent upon the wavelength, which corresponds to the effective length of the pump light. 相似文献
12.
Kazunori Tanaka Kaoru Okuno Tomoyuki Hattori Kiyoaki Moriuchi Hiroshi Hayami Wataru Katsurashima Yoshikyo Tamekuni 《光学学报》2003,23(Z1)
A non-halogen highly flame-retardant 0.9mm optical fiber and 2.0mm simplex optical cord, which are harmonized with the ecosystem, have been developed. The characteristics of them are presented in this paper. 相似文献
13.
Masayuki Kuzuya Akihiro Noguchi Hideki Ito Shin-Ichi Kondo Nahoko Noda 《Journal of polymer science. Part A, Polymer chemistry》1991,29(1):1-7
Plasma-induced polystyrene radicals were first studied by electron spin resonance (ESR). The room temperature ESR spectrum was compared with those obtained by γ-irradiation, UV-irradiation, and mechanical fracture. It was found that even less than a few seconds of plasma-irradiation gave rise to a large amount of polystyrene radicals and the ESR spectrum consisted of two types of spectra, a triplet and a single broad line. The spectral feature of the triplet was nearly identical with that of γ-irradiated polystyrene. Thus, it was assigned to the structure of a cyclohexadienyl-type radical formed by a nearly random addition of a hydrogen atom to the aromatic ring. The single broad line, thought to be an outline of multicomponent spectrum, was assigned to an immobilized dangling-bond sites at the plasma-induced crosslinked portion of the polystyrene surface. 相似文献
14.
15.
Keigo Fugami Takashi Nishikata Masayuki Kameyama 《Journal of organometallic chemistry》2003,687(2):567-569
Palladium-catalyzed reaction between 1-alkenyltin trichlorides and norbornene resulted in stereoselective formation of 3-alkylidenepentacyclo[9.2.1.5,81.1,110.2,1004,9]pentadecane instead of an expected simple alkenylstannylation product. Generation of trichlorostannane and its decomposition product, tin(II) chloride, was confirmed by trapping it with methyl propiolate and norbornene and analysis of the reaction by 119Sn NMR, respectively. 相似文献
16.
John A. Mikroyannidis Larysa Fenenko Masayuki Yahiro Chihaya Adachi 《Journal of polymer science. Part A, Polymer chemistry》2007,45(20):4661-4670
Three new copolymers, namely poly(fluorenevinylene‐alt‐naphthalenevinylene) ( N ), poly(fluorenevinylene‐alt‐anthracenevinylene) ( A ) and poly(fluorenevinylene‐alt‐pyrenevinylene) ( P ), were synthesized by Heck coupling of 9,9‐dihexyl‐2, 7‐divinylfluorene with a polynuclear aromatic dibromide. The 9,10‐disubstituted anthracene was obtained exclusively for A while N and P were obtained as a mixture of two isomers with predominant the 1,4‐disubstituted naphthalene and 1,8‐disubstituted pyrene, respectively. The polymers were soluble in common organic solvents and decomposed above 370 °C. Their glass transition temperature increased from 58 to 110 °C by increasing the number of the phenyl rings of the polynuclear aromatic moiety. Rather high‐efficiency blue and blue‐greenish photoluminescence (PL) of these copolymers in solution was largely decreased in their films, indicating the presence of concentration quenching in the solid state. The OLED using these polymers demonstrated green EL in the case of copolymers N and A , and red EL in the P derivative with ηEL = 0.26–0.31%. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4661–4670, 2007 相似文献
17.
Linear propagation of two pulses through methanol solution of aluminum phthalocyanine chloride is investigated using a modified white-light Michelson interferometer. The observed coherence time of the white light is 6 fs, and the separation between the two-excitation pulses is set to about 10 fs. The excitation is dependent on the phase-relation between the two pulses. We have observed an enhancement of the excitation when the two pulses are in-phase and strong suppression of the excitation when the two pulses are out of phase by π. 相似文献
18.
19.
20.