全文获取类型
收费全文 | 747篇 |
免费 | 25篇 |
专业分类
化学 | 526篇 |
晶体学 | 14篇 |
力学 | 11篇 |
数学 | 65篇 |
物理学 | 156篇 |
出版年
2023年 | 4篇 |
2022年 | 7篇 |
2021年 | 6篇 |
2020年 | 7篇 |
2019年 | 5篇 |
2018年 | 5篇 |
2017年 | 4篇 |
2016年 | 13篇 |
2015年 | 18篇 |
2014年 | 16篇 |
2013年 | 28篇 |
2012年 | 24篇 |
2011年 | 31篇 |
2010年 | 21篇 |
2009年 | 23篇 |
2008年 | 30篇 |
2007年 | 37篇 |
2006年 | 31篇 |
2005年 | 27篇 |
2004年 | 28篇 |
2003年 | 32篇 |
2002年 | 36篇 |
2001年 | 27篇 |
2000年 | 17篇 |
1999年 | 14篇 |
1998年 | 15篇 |
1997年 | 9篇 |
1996年 | 18篇 |
1995年 | 17篇 |
1994年 | 17篇 |
1993年 | 13篇 |
1992年 | 17篇 |
1991年 | 12篇 |
1990年 | 9篇 |
1989年 | 14篇 |
1988年 | 8篇 |
1987年 | 10篇 |
1986年 | 11篇 |
1985年 | 8篇 |
1984年 | 19篇 |
1983年 | 7篇 |
1982年 | 9篇 |
1981年 | 9篇 |
1980年 | 8篇 |
1979年 | 4篇 |
1978年 | 8篇 |
1977年 | 9篇 |
1976年 | 5篇 |
1975年 | 5篇 |
1970年 | 3篇 |
排序方式: 共有772条查询结果,搜索用时 0 毫秒
81.
E. Ramos T. Lopez P. Bosch M. Asomoza R. Gomez 《Journal of Sol-Gel Science and Technology》1997,8(1-3):437-442
Sol-Gel Hydrotalcites were synthesized using magnesium ethoxide and variable aluminum sources: aluminum acetilacetonate, aluminum
chloride, aluminum nitrate and aluminum sulfate; in all cases, the gelation was done at pH 10. X-ray diffraction studies show
that the crystallinity depends on the aluminum precursor used. The crystallinity was found in the order aluminum acetylcetonate>aluminum
chloride>aluminum nitrate>aluminum sulfate. The precursor determines the sintering behavior as well. 相似文献
82.
We prove an extension of Ekeland's variational principle to locally complete spaces which uses subadditive, strictly increasing continuous functions as perturbations. 相似文献
83.
84.
85.
Dr. Concha Bosch‐Navarro Zachary P. L. Laker Helen R. Thomas Alexander J. Marsden Dr. Jeremy Sloan Dr. Neil R. Wilson Dr. Jonathan P. Rourke 《Angewandte Chemie (International ed. in English)》2015,54(33):9560-9563
Atomic‐resolution transmission electron microscopy was used to identify individual Au9 clusters on a sulfur‐functionalized graphene surface. The clusters were preformed in solution and covalently attached to the surface without any dispersion or aggregation. Comparison of the experimental images with simulations allowed the rotational motion, without lateral displacement, of individual clusters to be discerned, thereby demonstrating a robust covalent attachment of intact clusters to the graphene surface. 相似文献
86.
Isothermal titration calorimetry (ITC) is used to study the complexation thermodynamics of Ni(II) with histidine (His) and with N-2-aminoethylglycine (EDMA). The titrations were performed in HEPES and Tris buffers at various ionic strengths and pH values around 8. The results show the influence of the experimental conditions on the shape and fitting parameters of the calorimetric curves. For the studied systems, the main reaction is concomitant with a number of side reactions which contribute to the global energy measured. From the calorimetric data measured, the formation constants for the species NiHEPES+, Tris+His−, TrisNiHis+ and [Ni(EDMA)2OH]− have been evaluated for the first time and the values obtained properly validated. 相似文献
87.
Xiong S Molecke R Bosch M Schunk PR Brinker CJ 《Journal of the American Chemical Society》2011,133(30):11410-11413
Transformation of 2D Au nanoparticle (NP) arrays into large scale, ordered, and oriented nanorod/nanowire arrays supported on a transferrable polymer film has been accomplished. E-beam irradiation followed by room temperature aging of a suspended Au NP/polymethylmethacrylate (PMMA) polymer close packed monolayer results in one-dimensional nanoparticle aggregation, reorientation, and sintering into a high density array of oriented Au nanowires with coherent single-crystal-like interfaces. Molecular dynamics simulations of alkane-thiol capped Au NPs, interacting through the Vincent potential and undergoing 2D Poisson compression, account semiquantitatively for the qualitative features of the transformation. This fabrication approach should be extendable to directing 1D aggregation of highly anisotropic nanostructures in arbitrary NP systems. 相似文献
88.
The double cyclocondensation of symmetric pyridyl bis(oxoacids) 2b and 3b with (R)-phenylglycinol stereoselectively gave access to bis-phenylglycinol-derived oxazolopyrrolidine 9 and oxazolopiperidone 10, respectively. Application of the stereocontrolled cyclocondensation reaction to phenyl bis-γ-oxoacid 4b provided 11, which was converted to the corresponding enantiopure di(pyrrolidinyl)benzene 22. The absolute configuration of the new stereogenic centers generated in the key cyclocondenstion step was unambiguously established by X-ray crystallographic analysis. 相似文献
89.
This review is focused on recent synthetic achievements and ongoing work in our laboratory using phenylglycinol-derived oxazolopiperidone lactams as starting materials for the enantioselective synthesis of piperidine-containing alkaloids: madangamines, 2,5-disubstituted decahydroquinoline and 1-substituted tetrahydroisoquinoline alkaloids, the indole alkaloids 20S- and 20R-dihydrocleavamine and quebrachamine, and indole alkaloids of the uleine and silicine groups. 相似文献
90.
We obtain characterizations of positive Borel measures μ on B
n
so that some weighted holomorphic Besov spaces B
s
p
(ω,B
n
) are embedded in L
p
(d
μ). 相似文献