全文获取类型
收费全文 | 528篇 |
免费 | 28篇 |
国内免费 | 9篇 |
专业分类
化学 | 422篇 |
晶体学 | 4篇 |
力学 | 10篇 |
数学 | 53篇 |
物理学 | 76篇 |
出版年
2023年 | 5篇 |
2021年 | 5篇 |
2020年 | 22篇 |
2019年 | 9篇 |
2018年 | 15篇 |
2017年 | 3篇 |
2016年 | 11篇 |
2015年 | 10篇 |
2014年 | 17篇 |
2013年 | 20篇 |
2012年 | 35篇 |
2011年 | 23篇 |
2010年 | 14篇 |
2009年 | 21篇 |
2008年 | 29篇 |
2007年 | 29篇 |
2006年 | 23篇 |
2005年 | 24篇 |
2004年 | 22篇 |
2003年 | 22篇 |
2002年 | 19篇 |
2001年 | 20篇 |
2000年 | 6篇 |
1999年 | 14篇 |
1998年 | 12篇 |
1997年 | 6篇 |
1996年 | 8篇 |
1995年 | 5篇 |
1994年 | 6篇 |
1993年 | 5篇 |
1992年 | 6篇 |
1991年 | 4篇 |
1990年 | 3篇 |
1989年 | 6篇 |
1988年 | 13篇 |
1987年 | 9篇 |
1986年 | 7篇 |
1985年 | 13篇 |
1984年 | 2篇 |
1983年 | 4篇 |
1977年 | 4篇 |
1976年 | 3篇 |
1975年 | 8篇 |
1974年 | 3篇 |
1973年 | 1篇 |
1972年 | 3篇 |
1970年 | 1篇 |
1969年 | 6篇 |
1968年 | 3篇 |
1958年 | 2篇 |
排序方式: 共有565条查询结果,搜索用时 31 毫秒
141.
142.
Uchiyama M Furuyama T Kobayashi M Matsumoto Y Tanaka K 《Journal of the American Chemical Society》2006,128(26):8404-8405
A versatile preparation method for aromatic zincate compounds through a halogen-zinc exchange reaction using dilithium tetra-tert-butylzincate (tBu4ZnLi2) has been developed. This reagent permits efficient preparation of highly functionalized aromatic zincates, particularly, those with electrophilic functional groups, such as ester, amide, alcohol, and phenol. Halogen-zinc exchange reactions followed by electrophilic trapping (with allyl bromide or benzaldehyde) proved to be a powerful tool for C-C bond formation on functionalized aromatic rings. The functionalized aromatic zincate intermediate was also found to undergo copper- and palladium-catalyzed C-C bond-forming reactions with good yields and high chemoselectivity. 相似文献
143.
Uchiyama M Matsumoto Y Nobuto D Furuyama T Yamaguchi K Morokuma K 《Journal of the American Chemical Society》2006,128(27):8748-8750
The novel directed ortho metalation (DoM) reagents for functionalized aromatic rings, TMP-Zn-ates (R2Zn(TMP)Li (R = Me, 1; tBu, 2)), have been reported to be synthetically useful for the chemo- and regioselective construction of multi-functionalized aromatic compounds. Here, we present the first comprehensive structural and mechanistic investigation by means of X-ray, NMR, and DFT studies on the DoM reaction employing our original TMP-Zn-ate base. The structures of TMP-Zn-ates in solution and in the solid state were determined. The DFT study strongly suggested that the deprotonation involving the TMP ligand on the TMP-Zn-ate is kinetically more favorable than that involving the alkyl ligand, and this view was supported by monitoring of the 13C NMR spectrum of the reaction mixture. 相似文献
144.
Mitsuru Uchiyama 《Proceedings of the American Mathematical Society》2006,134(5):1405-1412
Let be a nonnegative concave function on with , and let be matrices. Then it is known that , where is the trace norm. We extend this result to all unitarily invariant norms and prove some inequalities of eigenvalue sums.
145.
Mitsuru Uchiyama 《Journal of Functional Analysis》2006,231(1):221-244
Let P+ be the set of all non-negative operator monotone functions defined on [0,∞), and put . Then and . For a function and a strictly increasing function h we write if is operator monotone. If and and if and , then . We will apply this result to polynomials and operator inequalities. Let and be non-increasing sequences, and put for t≧a1 and for t≧b1. Then v+?u+ if m≦n and : in particular, for a sequence of orthonormal polynomials, (pn-1)+?(pn)+. Suppose 0<r,p and s=0 or 1≦s≦1+p/r. Then 0≦A≦B implies for 0<α≦r/(p+r). 相似文献
146.
Nakai N Miranović P Ichioka M Hess HF Uchiyama K Nishimori H Kaneko S Nishida N Machida K 《Physical review letters》2006,97(14):147001
It is demonstrated theoretically and experimentally that the low energy density of states N(E) is described by a singular V-shape form N(E)=N(0)(H)+alpha|E|+O(E2) for all clean superconductors in a vortex state, irrespective of the underlying gap structure. The linear term alpha|E| which has not been recognized so far is obtained by exactly evaluating the vortex contribution. Based on microscopic Eilenberger theory N(E) is evaluated for the isotropic gap, line, and point-node gaps to yield a V-shape N(E). Scanning tunneling spectroscopy-STM experiments on NbSe2 and YNi2B2C give direct evidence for this. We provide arguments on the significance of this finding and on the relevance to other experiments. 相似文献
147.
148.
Ritsuko Matsukawa Kiyotaka Hatakeda Shota Ito Yukiyo Numata Hidetoshi Nakamachi Yasushi Hasebe Shunichi Uchiyama Masahiro Notoya Zvy Dubinsky Isao Karube 《Applied biochemistry and biotechnology》1999,80(2):141-150
Forty-eight species of seaweeds from Japanese waters were screened for the valuable polyunsaturated fatty acids eicosapentaenoic
acid (EPA). The eight species that contained the highest levels of these compounds were analyzed in detail. Of all species
tested the red alga Pachymeniopsis lanceolata contained the highest EPA concentration, and it was present as both the free and bound forms. EPA constituted 38.7% of total
fatty acids, and polar lipids were the main constituent of the total lipids in P. lanceolata. EPA was obtained from the marine algae P. lanceolata by enzymatic hydrolysis of the total lipids extract using phospholipase A2(PLA2). The release of EPA reached a plateau after 10 min of enzymatic treatment. These results suggest that P. lanceolata is a useful natural source of EPA and that PLA2 treatment is a convenient method for obtaining EPA from the red alga. 相似文献
149.
Atsushi Uchiyama 《Integral Equations and Operator Theory》1999,33(2):221-230
For an-multicyclicp-hyponormal operatorT, we shall show that |T|2p
–|T
*|2p
belongs to the Schatten
and that tr
Area ((T)). 相似文献
150.
K. Tanahashi A. Uchiyama M. Uchiyama 《Proceedings of the American Mathematical Society》2003,131(8):2549-2552
We show Schwarz type inequalities and consider their converses. A continuous function is said to be semi-operator monotone on if is operator monotone on . Let be a bounded linear operator on a complex Hilbert space and be the polar decomposition of . Let and for . (1) If a non-zero function is semi-operator monotone on , then for , where . (2) If are semi-operator monotone on , then for . Also, we show converses of these inequalities, which imply that semi-operator monotonicity is necessary.