全文获取类型
收费全文 | 1867篇 |
免费 | 66篇 |
国内免费 | 8篇 |
专业分类
化学 | 1483篇 |
晶体学 | 31篇 |
力学 | 29篇 |
数学 | 174篇 |
物理学 | 224篇 |
出版年
2023年 | 9篇 |
2022年 | 10篇 |
2021年 | 17篇 |
2020年 | 24篇 |
2019年 | 33篇 |
2018年 | 19篇 |
2017年 | 21篇 |
2016年 | 39篇 |
2015年 | 40篇 |
2014年 | 42篇 |
2013年 | 102篇 |
2012年 | 119篇 |
2011年 | 127篇 |
2010年 | 67篇 |
2009年 | 68篇 |
2008年 | 120篇 |
2007年 | 119篇 |
2006年 | 113篇 |
2005年 | 102篇 |
2004年 | 96篇 |
2003年 | 88篇 |
2002年 | 72篇 |
2001年 | 15篇 |
2000年 | 29篇 |
1999年 | 13篇 |
1998年 | 25篇 |
1997年 | 23篇 |
1996年 | 22篇 |
1995年 | 15篇 |
1993年 | 15篇 |
1992年 | 17篇 |
1991年 | 12篇 |
1990年 | 14篇 |
1989年 | 12篇 |
1988年 | 8篇 |
1987年 | 17篇 |
1985年 | 18篇 |
1984年 | 20篇 |
1983年 | 19篇 |
1982年 | 24篇 |
1981年 | 17篇 |
1980年 | 27篇 |
1979年 | 15篇 |
1978年 | 16篇 |
1977年 | 7篇 |
1976年 | 16篇 |
1975年 | 14篇 |
1974年 | 15篇 |
1973年 | 12篇 |
1969年 | 7篇 |
排序方式: 共有1941条查询结果,搜索用时 109 毫秒
991.
992.
Fumitoshi Sato Tamotsu Yoshihiro Isao Okazaki Hiroshi Kashiwagi 《Chemical physics letters》1999,310(5-6)
An all-electron calculation of the antihypertensive and antiviral protein BDS-I from the sea anemone Anemonia sulcata was carried out using the density functional method based on Gaussian-type orbitals with workstations. Our computer program ProteinDF coded by the object-oriented language C++, was originally designed for all-electron calculations of proteins and controlled in parallel with high efficiency. The numbers of residues, atoms, orbitals and auxiliary functions of the calculated protein were 43, 629, 3615 and 6545, respectively. This Letter reports timing data of the computation and some calculated electronic properties. Our program will open the door for advanced studies of larger proteins. 相似文献
993.
We prove a new relation for the multiple q-zeta values (MqZV’s). It is a q-analogue of the Ohno-Zagier relation for the multiple zeta values (MZV’s). We discuss the problem of determining the dimension
of the space spanned by MqZV’s over ℚ, and present an application to MZV.
The first author is supported by Grant-in-Aid for Young Scientists (B) No. 17740026 and the second author is supported by
Grant-in-Aid for Young Scientists (B) No. 17740089. 相似文献
994.
995.
Daisuke Hirabayashi Yoichi Sakai Takeshi Yoshikawa Kazuhiro Mochizuki Yoshihiro Kojima Kenzi Suzuki Kazumasa Ohshita Yasuo Watanabe 《Hyperfine Interactions》2006,167(1-3):809-813
Calcium ferrite oxides were prepared by calcining a mixture powder of iron- and calcium oxide. The 57Fe-Mössbauer spectra of the calcium ferrites oxides were measured, revealing that the products should be Ca2Fe2O5 and CaFe2O4, the ratio of which was dependent of the Fe/Ca atomic ratio of the mixture powder. 相似文献
996.
Yoshihiro Matsumura Toshihide Maki Kazuya Tsurumaki Osamu Onomura 《Tetrahedron letters》2004,45(49):9131-9134
Kinetic resolution of d,l-myo-inositol derivatives having a 1,2-diol functionality by monobenzoylation was achieved using (R,R)-Ph-BOX-Cu(II) as a catalyst. The monobenzoylation preferentially took place at the 1,2-diol functionality via a highly enantiodiscriminatory process, which was largely influenced by a substituent at the position adjacent to the 1,2-diol functionality. This method was applied to a synthesis of biologically important d-inositol-1-phosphate. 相似文献
997.
This paper describes a change in optical spectrum on propagation in free space for a particular class of spatially partially coherent fields emanating from a polychromatic secondary source. A rectangular opening aperture in an opaque screen, illuminated with an extended incoherent polychromatic primary source, works as the secondary source. The spectral change is explored in detail theoretically and experimentally in association with spatial coherence in the secondary source as well as dispersive diffraction by the secondary source. The peak shift of the spectrum is associated with the coherence area for characterizing the secondary source. The peak shift becomes maximum if the secondary source is spatially coherent, but no shift occurs if the secondary source is spatially incoherent. 相似文献
998.
Linxiang Li Yoshihiro Abe Tadahiko Mashino Masataka Mochizuki Naoki Miyata 《Analytical sciences》2003,19(7):1083-1084
In an ESR spin-trapping measurement of hydroxyl radicals formed in a Fenton reaction, the trapping efficiency with DMPO increased by about 300 times in a sodium trifluoroacetate solution, whereas it was little changed in a phosphate buffer. 相似文献
999.
Self-decomposable distributions are given as limits of normalized sums of independent random variables. We define semi-selfdecomposable
distributions as limits of subsequences of normalized sums. More generally, we introduce a way of making a new class of limiting
distributions derived from a class of distributions by taking the limits through subsequences of normalized sums, and define
the class of semi-selfdecomposable distributions and a decreasing sequence of subclasses of it. We give two kinds of necessary
and sufficient conditions for distributions belonging to those classes, one is in terms of the decomposability of random variables
and another is in terms of Lévy measures.
Received: 1 May 1997 / Revised version: 5 February 1998 相似文献
1000.
Yoshihiko Omura Eiko Renbutsu Minoru Morimoto Hiroyuki Saimoto Yoshihiro Shigemasa 《先进技术聚合物》2003,14(1):35-39
New chitosan derivatives are synthesized by the reductive N‐alkylation reaction of chitosan with various aldehydes, such as 2,4‐dihydroxybenzaldehyde, cholesteryl 4‐formylbenzoate, and N‐dehydroabietyl‐4‐formylbenzamide. The palladium‐adsorption ability of the newly synthesized derivatives is found to be as good as that of chitosan. A blend of chitosan and other biodegradable polymers is also found to exhibit palladium‐adsorption ability. In comparison to the starting chitosan, the chitosan derivative having dehydroabietyl‐type side chains exhibited an improved solubility in methanol. The chitosan derivatives are successfully applied as plastic coating materials for electroless plating. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献