全文获取类型
收费全文 | 572篇 |
免费 | 19篇 |
国内免费 | 1篇 |
专业分类
化学 | 409篇 |
晶体学 | 4篇 |
力学 | 11篇 |
数学 | 25篇 |
物理学 | 143篇 |
出版年
2023年 | 7篇 |
2022年 | 11篇 |
2021年 | 11篇 |
2020年 | 11篇 |
2019年 | 10篇 |
2018年 | 6篇 |
2017年 | 9篇 |
2016年 | 15篇 |
2015年 | 12篇 |
2014年 | 11篇 |
2013年 | 23篇 |
2012年 | 50篇 |
2011年 | 38篇 |
2010年 | 9篇 |
2009年 | 22篇 |
2008年 | 28篇 |
2007年 | 31篇 |
2006年 | 17篇 |
2005年 | 28篇 |
2004年 | 22篇 |
2003年 | 25篇 |
2002年 | 22篇 |
2001年 | 16篇 |
2000年 | 19篇 |
1999年 | 7篇 |
1998年 | 9篇 |
1997年 | 6篇 |
1996年 | 6篇 |
1995年 | 4篇 |
1994年 | 4篇 |
1993年 | 8篇 |
1992年 | 12篇 |
1991年 | 4篇 |
1990年 | 3篇 |
1989年 | 7篇 |
1987年 | 9篇 |
1986年 | 4篇 |
1985年 | 8篇 |
1984年 | 6篇 |
1983年 | 6篇 |
1982年 | 4篇 |
1981年 | 4篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 4篇 |
1976年 | 3篇 |
1975年 | 3篇 |
1974年 | 3篇 |
1973年 | 3篇 |
排序方式: 共有592条查询结果,搜索用时 906 毫秒
91.
Soga T Ishikawa T Igarashi S Sugawara K Kakazu Y Tomita M 《Journal of chromatography. A》2007,1159(1-2):125-133
A method for the determination of nucleotides based on pressure-assisted capillary electrophoresis-electrospray ionization mass spectrometry (PACE-MS) is described. To prevent multi-phosphorylated species from adsorbing onto the fused-silica capillary, silanol groups were masked with phosphate ions by preconditioning the capillary with the background electrolyte containing phosphate. During preconditioning, nebulizer gas was turned off to avoid contamination of MS detector with phosphate ions. To detect nucleotides using the CE positive mode at a pH 7.5, it was necessary to apply air pressure to the inlet capillary during electrophoresis to supplement the electroosmotic flow (EOF) toward the cathode. Moreover, we exchanged the running electrolyte every analysis using the buffer replenishment system to obtain the required reproducibility. Under the optimized conditions, 14 phosphorylated species such as nucleotides, nicotinamide-adenine dinucleotides and coenzyme A (CoA) compounds were well determined in less than 20 min. The relative standard deviations (n=6) of the method were better than 0.9% for migration times and between 1.7% and 8.1% for peak areas. The detection limits for these species were between 0.5 and 1.7 micromol/L with pressure injection of 50 mbar for 30 s (30 nL) at a signal-to-noise ratio of 3. This approach is robust and quantitative compared to the previous method, and its utility is demonstrated by the analysis of intracellular nucleotides and CoA compounds extracted from Escherichia coli wild type, pfkA and pfkB knockout mutants. The methodology was used to suggest that pfkA is the main functional enzyme. 相似文献
92.
Y. Yoda H. Igarashi X.W. Zhang Y. Imai T. Mitsui I. Koyama S. Kikuta 《Hyperfine Interactions》2000,126(1-4):435-441
Multiple nuclear resonant scattering from an 57FeBO3 single crystal has been observed in the three-beam case. A change of the lifetime and a modulation of the quantum beat were
observed in our study. The high brilliance of synchrotron radiation and the high perfection of the synthetic 57FeBO3 single crystal enabled us to observe such an effect.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
93.
Kousaku Ohkawa Kengo Ichimiya Ayako Nishida Hiroyuki Yamamoto 《Macromolecular bioscience》2001,1(9):376-386
The adhesive polydecapeptide poly(Lys‐Pro‐Thr‐Gln‐Tyr‐Ser‐Asp‐Glu‐Tyr‐Lys) (average repeating number, n = 5), which is the consensus sequence of the Asian freshwater mussel Limnoperna fortunei adhesive protein (Lffp), has been synthesized by the polycondensation of the active esters. The surface chemical experiments revealed the following characteristics of the freshwater adhesive protein: (i) wettability of the Lffp solution is affected by the polar component value (γsp) of the surface free energy of the substrate, and a substrate having a γsp less than 10 mJ·m–2 exhibits a reduced wettability of the Lffp solution; (ii) the comparison of wettability of native Lffp with synthetic Lffp suggests that the decapeptide sequence, ‐Lys‐Pro‐Thr‐Gln‐Tyr‐Ser‐Asp‐Glu‐Tyr‐Lys‐, contributes to the interaction with the underwater surface; (iii) the Lffp tends to adsorb on nonpolar surfaces that have a low γsp value; and (iv) the adsorption ability of the freshwater adhesive protein is less than that of the marine adhesive protein because of the higher hydrophilicity of the freshwater adhesive protein. An antifouling examination indicated that a γsp value of the substrate surface of less than 10 mJ·m–2 should achieve a higher antifouling effect towards the L. fortunei attachment. These results are the first findings for the development of a freshwater antifouling strategy based on the molecular mechanism underlying the attachment of L. fortunei. 相似文献
94.
95.
This review paper reports near-infrared (NIR) imaging studies using a newly-developed NIR camera, Compovision. Compovision can measure a significantly wide area of 150 mm×250 mm at high speed of between 2 and 5 s. It enables a wide spectral region measurement in the 1 000~2 350 nm range at 6 nm intervals. We investigated the potential of Compovision in the applications to industrial problems such as the evaluation of pharmaceutical tablets and polymers. Our studies have demonstrated that NIR imaging based on Compovision can solve several issues such as long acquisition times and relatively low sensitivity of detection. NIR imaging with Compovision is strongly expected to be applied not only to pharmaceutical tablet monitoring and polymer characterization but also to various applications such as those to food products, biomedical substances and organic and inorganic materials. 相似文献
96.
Epitaxial Sb-doped SnO2 (0 0 1) thin film on a TiO2 (0 0 1) substrate was successfully prepared by laser-assisted metal organic deposition at room temperature. The effects of the precursor thin film and laser fluence on the resistivity, carrier concentration, and mobility of the Sb-doped SnO2 film were investigated. The resistivity of the Sb-doped SnO2 film prepared by direct irradiation to metal organic film is one order of magnitude lower than that of film prepared by irradiation to amorphous Sb-doped SnO2 film. From an analysis of Hall measurements, the difference between the resistivity of the Sb-doped SnO2 film prepared using the metal organic precursor film and that of amorphous precursor film appears to be caused by the mobility. Direct conversion of the metal organic compound by excimer laser irradiation was found to be effective for preparing epitaxial Sb-doped SnO2 film with low resistivity. 相似文献
97.
Atsuya Muranaka Dr. Osamu Matsushita Kengo Yoshida Shigeki Mori Dr. Masaaki Suzuki Dr. Taniyuki Furuyama Masanobu Uchiyama Prof. Dr. Atsuhiro Osuka Prof. Dr. Nagao Kobayashi Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(15):3744-3751
Expanded porphyrins : The electronic excited states of two forms of meso‐hexakis(pentafluorophenyl)‐substituted gold(III) hexaphyrin(1.1.1.1.1.1), such as that depicted, have been investigated by density functional calculations and magnetic circular dichroism spectroscopy to assign their low‐energy excited singlet states.
98.
Kengo Kato 《Annals of the Institute of Statistical Mathematics》2009,61(3):531-542
The prediction problem for a multivariate normal distribution is considered where both mean and variance are unknown. When
the Kullback–Leibler loss is used, the Bayesian predictive density based on the right invariant prior, which turns out to
be a density of a multivariate t-distribution, is the best invariant and minimax predictive density. In this paper, we introduce an improper shrinkage prior
and show that the Bayesian predictive density against the shrinkage prior improves upon the best invariant predictive density
when the dimension is greater than or equal to three. 相似文献
99.
100.
Kengo Yoshida Mitsutoshi Kuroda 《International Journal of Solids and Structures》2012,49(15-16):2073-2084
Plastic flow localization into a narrow band is investigated for a rate-independent polycrystalline sheet. Strain localization is considered to initiate at a point of bifurcation from the homogeneous deformation state or to result from the growth of a preexisting imperfection. Bifurcation analysis based on the rate-independent crystal plasticity model is found to give limit strains at a realistic strain level in the biaxial-stretching range. Limit strains predicted by the imperfection analysis are lower than those for bifurcation analysis and tend to approach those strain levels with decreasing amount of initial imperfection. Then, the bifurcation analysis is applied to the simulation of the forming limit for strongly textured sheets. The bifurcation analysis reveals the same trend of a texture dependence of limit strains as that for the imperfection analysis employing a rate-dependent model reported in the literature. 相似文献