全文获取类型
收费全文 | 502篇 |
免费 | 5篇 |
国内免费 | 14篇 |
专业分类
化学 | 212篇 |
晶体学 | 1篇 |
力学 | 4篇 |
数学 | 158篇 |
物理学 | 146篇 |
出版年
2019年 | 6篇 |
2018年 | 7篇 |
2017年 | 5篇 |
2016年 | 11篇 |
2015年 | 12篇 |
2014年 | 13篇 |
2013年 | 25篇 |
2012年 | 20篇 |
2011年 | 13篇 |
2010年 | 10篇 |
2008年 | 20篇 |
2007年 | 9篇 |
2006年 | 8篇 |
2004年 | 14篇 |
2003年 | 11篇 |
2002年 | 7篇 |
2001年 | 15篇 |
2000年 | 8篇 |
1999年 | 8篇 |
1998年 | 10篇 |
1997年 | 11篇 |
1996年 | 7篇 |
1995年 | 7篇 |
1994年 | 11篇 |
1993年 | 6篇 |
1992年 | 13篇 |
1991年 | 7篇 |
1990年 | 6篇 |
1988年 | 8篇 |
1987年 | 5篇 |
1985年 | 7篇 |
1983年 | 7篇 |
1980年 | 6篇 |
1978年 | 6篇 |
1977年 | 9篇 |
1976年 | 5篇 |
1974年 | 6篇 |
1973年 | 8篇 |
1972年 | 7篇 |
1971年 | 5篇 |
1968年 | 5篇 |
1967年 | 5篇 |
1935年 | 5篇 |
1933年 | 6篇 |
1927年 | 5篇 |
1926年 | 5篇 |
1924年 | 6篇 |
1920年 | 5篇 |
1911年 | 5篇 |
1908年 | 5篇 |
排序方式: 共有521条查询结果,搜索用时 15 毫秒
31.
32.
33.
S. Haiber H. Herzog P. Burba B. Gosciniak J. Lambert 《Analytical and bioanalytical chemistry》2001,369(5):457-460
Two-dimensional phase sensitive C,H correlation spectra were successfully applied to the quantification of carbohydrate substructures in aquatic humic substance (HS) fractions obtained by tangential flow multistage ultrafiltration (TFMSTUF) of a selected bog water HS (HO13, German Research Program DFG-ROSIG) as well as a river HS (Suwannee River Fulvic Acid Reference of the International Humic Substances Society, IHSS). It turns out that after size fractionation the HS samples give very well resolved C,H-correlation spectra which offer a great potential for substructure quantification. Details of the combined substructure quantification technique, novel in HS characterization, are presented. The results of the combined procedure point out that carbohydrate moieties predominantly occur in higher molecular mass fractions (> 10 kDa) of isolated HS. 相似文献
34.
R. O. Herzog 《Colloid and polymer science》1907,2(1):1-2
Ohne Zusammenfassungnach Versuchen von H. Kasarnowski. 相似文献
35.
36.
Charles Doran Matthew Headrick Christopher P. Herzog Joshua Kantor Toby Wiseman 《Communications in Mathematical Physics》2008,282(2):357-393
The third del Pezzo surface admits a unique Kähler-Einstein metric, which is not known in closed form. The manifold’s toric structure reduces the Einstein equation to a single Monge-Ampère equation in two real dimensions. We numerically solve this nonlinear PDE using three different algorithms, and describe the resulting metric. The first two algorithms involve simulation of Ricci flow, in complex and symplectic coordinates respectively. The third algorithm involves turning the PDE into an optimization problem on a certain space of metrics, which are symplectic analogues of the “algebraic” metrics used in numerical work on Calabi-Yau manifolds. Our algorithms should be applicable to general toric manifolds. Using our metric, we compute various geometric quantities of interest, including Laplacian eigenvalues and a harmonic (1,1)-form. The metric and (1,1)-form can be used to construct a Klebanov-Tseytlin-like supergravity solution. 相似文献
37.
The magnetic hyperfine interaction of 60Co in the completely miscible alloy Co
x
Pd1−x
was investigated for different values of x by measuring the nuclear orientation of 60Co as function of temperature and by nuclear magnetic resonance of the oriented 60Co nuclei. A broad resonance signal of Gaussian shape could be observed down to x=60%. The dependence of the mean magnetic hyperfine field on the Co concentration was observed to be linear very similar to
that of experimental values of the magnetic moment per atom in the literature. The magnetic hyperfine field and its broad
distribution are discussed in a simple model with RKKY interaction.
This revised version was published online in September 2006 with corrections to the Cover Date. 相似文献
38.
A Herzog C B Knobler M F Hawthorne 《Journal of the American Chemical Society》2001,123(51):12791-12797
The reaction of closo-1,12-bis(lithio)-1,12-dicarbadodecaborane(12) (1,12-bis(lithio)-p-carborane) with SO(2) formed closo-1,12-bis(lithiosulfinato)-p-carborane (10) in nearly quantitative yield. The latter was converted to closo-1,12-bis(sulfinic acid)-p-carborane (13) via H(+)-exchange. The corresponding 1,12-bis(sulfonic acid) derivative of p-carborane (12) was obtained in high yield by treating 10 with SO(2)Cl(2) and subsequent AlCl(3) mediated hydrolysis of the closo-1,12-bis(chlorosulfonyl)-p-carborane intermediate. The exhaustive oxidation of 12 in hot aqueous H(2)O(2) (30%) afforded B-decahydroxy-1,12-bis(sulfonic acid)-p-carborane (15) in 40% yield. As a byproduct, closo-B-decahydroxy-1-sulfonic acid-p-carborane (14) was formed. Both 14 and 15 were also obtained from the hydroxylation of 10 and 13. Compound 14 was obtained directly in 88% yield by heating 1-sulfinic acid-p-carborane (17) in H(2)O(2) (30%). Compound 17 was synthesized from diphenylmethylsilyl-protected p-carborane by using the method employed in the synthesis of 13. The X-ray structures of 15, its disodium salt, and its dipotassium salt are presented and discussed. Exhaustive methylation of 15 with methyl triflate furnishes closo-B-decamethoxy-1,12-bis(methyl sulfonate)-p-carborane (20). The characterization of closomer 20 also includes its crystal structure determination. 相似文献
39.
Jrg Lambert Stephan Haiber Helmut Herzog 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2001,150(2):175
A new two-dimensional pulse sequence for T2* measurement of protons directly coupled to 13C spins is proposed. The sequence measures the tranverse relaxation time of heteronuclear proton single-quantum coherence under conditions of free precession and is therefore well suited to evaluate relaxation losses of proton magnetization during preparation delays of heteronuclear pulse experiments in analytical NMR. The relevant part of the pulse sequence can be inserted as a “building block” into any direct or inverse detecting H,C correlation pulse sequence if proton spin–spin relaxation is to be investigated. In this contribution, the building block is inserted into a HETCOR as well as into a HMQC pulse sequence. Experimental results for the HETCOR-based sequence are given. 相似文献
40.
Bergmann Ronny Herzog Roland Silva Louzeiro Maurcio Tenbrinck Daniel Vidal-Nez Jos 《Foundations of Computational Mathematics》2021,21(6):1465-1504
Foundations of Computational Mathematics - This paper introduces a new notion of a Fenchel conjugate, which generalizes the classical Fenchel conjugation to functions defined on Riemannian... 相似文献