全文获取类型
收费全文 | 618篇 |
免费 | 18篇 |
国内免费 | 6篇 |
专业分类
化学 | 336篇 |
力学 | 57篇 |
数学 | 114篇 |
物理学 | 135篇 |
出版年
2023年 | 5篇 |
2022年 | 9篇 |
2021年 | 22篇 |
2020年 | 17篇 |
2019年 | 17篇 |
2018年 | 13篇 |
2017年 | 10篇 |
2016年 | 33篇 |
2015年 | 20篇 |
2014年 | 16篇 |
2013年 | 34篇 |
2012年 | 41篇 |
2011年 | 48篇 |
2010年 | 23篇 |
2009年 | 21篇 |
2008年 | 43篇 |
2007年 | 22篇 |
2006年 | 32篇 |
2005年 | 21篇 |
2004年 | 27篇 |
2003年 | 15篇 |
2002年 | 11篇 |
2001年 | 12篇 |
2000年 | 8篇 |
1999年 | 7篇 |
1998年 | 4篇 |
1997年 | 4篇 |
1995年 | 6篇 |
1994年 | 5篇 |
1993年 | 5篇 |
1991年 | 5篇 |
1990年 | 8篇 |
1988年 | 4篇 |
1987年 | 6篇 |
1984年 | 3篇 |
1983年 | 5篇 |
1981年 | 5篇 |
1980年 | 4篇 |
1979年 | 2篇 |
1978年 | 5篇 |
1977年 | 4篇 |
1976年 | 3篇 |
1975年 | 5篇 |
1974年 | 4篇 |
1973年 | 6篇 |
1972年 | 2篇 |
1971年 | 3篇 |
1967年 | 2篇 |
1966年 | 2篇 |
1958年 | 2篇 |
排序方式: 共有642条查询结果,搜索用时 156 毫秒
101.
Labaziewicz J Ge Y Leibrandt DR Wang SX Shewmon R Chuang IL 《Physical review letters》2008,101(18):180602
Electric field noise from fluctuating patch potentials is a significant problem for a broad range of precision experiments, including trapped ion quantum computation and single spin detection. Recent results demonstrated strong suppression of this noise by cryogenic cooling, suggesting an underlying thermal process. We present measurements characterizing the temperature and frequency dependence of the noise from 7 to 100 K, using a single Sr+ ion trapped 75 mum above the surface of a gold plated surface electrode ion trap. The noise amplitude is observed to have an approximate 1/f spectrum around 1 MHz, and grows rapidly with temperature as T;{beta} for beta from 2 to 4. The data are consistent with microfabricated cantilever measurements of noncontact friction but do not extrapolate to the dc measurements with neutral atoms or contact potential probes. 相似文献
102.
103.
We present a logical framework for formalizing connections between finitary combinatorics and measure theory or ergodic theory that have appeared in various places throughout the literature. We develop the basic syntax and semantics of this logic and give applications, showing that the method can express the classic Furstenberg correspondence and to give short proofs of the Szemerédi Regularity Lemma and the hypergraph removal lemma. We also derive some connections between the modeltheoretic notion of stability and the Gowers uniformity norms from combinatorics. 相似文献
104.
Burstedde Carsten Holke Johannes Isaac Tobin 《Foundations of Computational Mathematics》2019,19(4):843-868
Foundations of Computational Mathematics - The Morton- or z-curve is one example for a space-filling curve: Given a level of refinement $$L \in \mathbb {N}_0$$ , it maps the interval $$[0, 2^{dL})... 相似文献
105.
Bedregal Patricia S. Ubillus Marco S. Poma Víctor R. Cohen Isaac M. 《Journal of Radioanalytical and Nuclear Chemistry》2018,315(3):695-701
Journal of Radioanalytical and Nuclear Chemistry - The methodology adopted at the Laboratory of Analytical Techniques of Instituto Peruano de Energía Nuclear for preparation of monitors and... 相似文献
106.
Proteins present in two mitochondria preparations were separated by 2-D chromatography using the ProteomeLab PF-2D Protein Fractional System, protein fractionation in two dimensions (PF-2D). The proteins in each first-dimension fraction were determined by trypsinization and LC-MS/MS. Chromatography peaks were quantified by UV detection using the "Mapping Tools" software (Beckman). The proteins present in UV detected peaks were trypsinized and identified by automated MS/MS sequencing. Relative amounts of the proteins present in the equivalent peak for each sample were assessed by comparison of the intensities of the constituent peptides and a predicted PF-2D value was calculated from the total ion count (TIC) for each peptide. Relative quantification for (18)O labeled peptides was performed using the ZoomQuant (v1.43b) software [1, 2]. We found that the chromatography peaks detected by UV generally contained several proteins. Using (18)O labeling we determined that in each peak the ratios of the constituent proteins were different. When these ratios were normalized using the TIC to account for abundance, the resulting ratio corresponded to that determined by UV. The predicted value for the PF-2D score corresponded to the observed value for each peak irrespective of the number or proteins detected. 相似文献
107.
Xiaole Weng Paul Boldrin Isaac Abrahams Suela Kellici 《Journal of solid state chemistry》2008,181(5):1123-1132
A new direct route for the “bottom up” syntheses of phases in the Lan+1NinO3n+1 series (n=1, 2, 3 and ∞) has been achieved via single-step heat treatments of nanosized co-crystallized precursors. The co-crystallized precursors were prepared using a continuous hydrothermal flow synthesis system that uses a superheated water flow at ca. 400 °C and 24.1 MPa to produce nanoparticulate slurries. Overall, a significant reduction in time and number of steps for the syntheses of La3Ni2O7 and La4Ni3O10 was achieved compared with more conventional synthesis methods, which typically require multiple homogenization and reheating steps over several days. 相似文献
108.
Isaac Pesenson 《Transactions of the American Mathematical Society》2008,360(10):5603-5627
A notion of Paley-Wiener spaces on combinatorial graphs is introduced. It is shown that functions from some of these spaces are uniquely determined by their values on some sets of vertices which are called the uniqueness sets. Such uniqueness sets are described in terms of Poincare-Wirtinger-type inequalities. A reconstruction algorithm of Paley-Wiener functions from uniqueness sets which uses the idea of frames in Hilbert spaces is developed. Special consideration is given to the -dimensional lattice, homogeneous trees, and eigenvalue and eigenfunction problems on finite graphs.
109.
Youxuan Zheng Majid Motevalli Rendy H.C. Tan Isaac Abrahams William P. Gillin Peter B. Wyatt 《Polyhedron》2008
3,4,5,6-Tetrafluoro-2-nitrophenoxide (L−) forms complexes with rare earth M3+ ions. X-ray crystal structures of substances with the stoichiometry Cs2ML5 · mEt2O (M = Er, m = 0; M = Er, m = 1; M = Y, m = 1.5; M = Yb, m = 1) have been determined. Each M3+ ion is coordinated to two bidentate and three monodentate L− ions; Et2O does not coordinate to M3+. The complexes absorb both visible and ultraviolet light. The solid Er3+ and Yb3+ complexes have unusually long lifetimes (τ = 20.2 μs and 142 μs, respectively) for the decay of their luminescence in the near-infrared region following photoexcitation; this is attributed to the lack of C–H bonds and other high frequency oscillators that could cause vibrational quenching. 相似文献
110.
Carrico IS 《Chemical Society reviews》2008,37(7):1423-1431
The use of synthetic molecules to modulate and track biological events is a central component of chemical biology. As a result, the precise, covalent modification of biomolecules is a key goal for this field. Several strategies have emerged that allow specific tailoring of polypeptides through either endogenous residues or introduced functionality. This tutorial review discusses these recent advances in the context of in vitro and in vivo applications. 相似文献