全文获取类型
收费全文 | 418篇 |
免费 | 18篇 |
国内免费 | 10篇 |
专业分类
化学 | 256篇 |
晶体学 | 1篇 |
力学 | 11篇 |
数学 | 63篇 |
物理学 | 115篇 |
出版年
2023年 | 2篇 |
2022年 | 3篇 |
2021年 | 8篇 |
2020年 | 11篇 |
2019年 | 7篇 |
2018年 | 7篇 |
2017年 | 4篇 |
2016年 | 15篇 |
2015年 | 6篇 |
2014年 | 9篇 |
2013年 | 12篇 |
2012年 | 35篇 |
2011年 | 26篇 |
2010年 | 24篇 |
2009年 | 24篇 |
2008年 | 44篇 |
2007年 | 25篇 |
2006年 | 23篇 |
2005年 | 23篇 |
2004年 | 14篇 |
2003年 | 20篇 |
2002年 | 13篇 |
2001年 | 6篇 |
2000年 | 9篇 |
1999年 | 8篇 |
1998年 | 1篇 |
1997年 | 6篇 |
1996年 | 8篇 |
1995年 | 2篇 |
1994年 | 2篇 |
1993年 | 5篇 |
1992年 | 4篇 |
1991年 | 4篇 |
1990年 | 8篇 |
1989年 | 3篇 |
1988年 | 5篇 |
1986年 | 6篇 |
1985年 | 1篇 |
1982年 | 1篇 |
1980年 | 4篇 |
1977年 | 1篇 |
1973年 | 1篇 |
1972年 | 2篇 |
1969年 | 2篇 |
1966年 | 1篇 |
1965年 | 1篇 |
排序方式: 共有446条查询结果,搜索用时 343 毫秒
1.
Ching Sum Hui Lillian Sze Man Lam Chun Yin Wai Kin Chan Aleksandra B. Djurii 《Journal of polymer science. Part A, Polymer chemistry》2003,41(11):1708-1715
Polyurethanes incorporated with rhenium diimine complexes were synthesized. The polymers exhibited interesting morphologies and solution properties. Results from gel permeation chromatography suggested the formation of polymer aggregates in solutions. The polymers could act as probes for metal ions. The addition of metal ions to polymer solutions led to significant changes in the electronic absorption properties of the polymer solutions. This was attributed to the interactions between the polyether moieties and metal ions. The metal complexes could also act as efficient photosensitizers. After doping with charge‐transport viologens, the photoconductivity of the polymers was greatly enhanced. The experimental quantum efficiency was simulated with Onsager's theory. The thermalization distances and the primary yields were typically 12–14 Å and 10?3, respectively. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1708–1715, 2003 相似文献
2.
Chi Kin Chau Kwang Mong Sim 《Operations Research Letters》2003,31(5):327-334
By showing that there is an upper bound for the price of anarchyρ(Γ) for a non-atomic congestion game Γ with only separable cost maps and fixed demands, Roughgarden and Tardos show that the cost of forgoing centralized control is mild. This letter shows that there is an upper bound for ρ(Γ) in Γ for fixed demands with symmetric cost maps. It also shows that there is a weaker bound for ρ(Γ) in Γ with elastic demands. 相似文献
3.
We present a theoretical analysis of corrugated long-period gratings in planar waveguides. In particular, we calculate the transmission spectra for both the TE and TM polarizations and highlight the polarization-independence conditions. 相似文献
4.
5.
The hydrothermal syntheses of the alkali metal molybdenum bronzes from starting solids (HxMoO3) with structural affinities to the desired products were investigated. Single-phase potassium blue and red bronzes were prepared by the hydrothermal treatments at around 430 K, and characterized by powder X-ray diffraction, IR spectroscopy, and SEM. The formation processes of these two bronzes during the hydrothermal treatments were found to differ. The blue bronze was formed by a structure-inheriting solid-state route from HxMoO3 with x<0.3, whereas the red bronze was formed for x>0.3 through a solution dissolution/deposition route via the formation of MoO3+MoO2. 相似文献
6.
The preparation of pyrimidine-2-thione, pyrimidine-2-one, pyrimidine, and benzo[b][1,4]diazepine derivatives using traceless solid-phase sulfone linker strategy is described. Key steps involved are (i) sulfinate S-alkylation, (ii) sulfone anion alkylation with an epoxide, (iii) gamma-hydroxyl sulfone --> gamma-ketosulfone oxidation, and (iv) traceless product release by a one-pot elimination-cyclization process. Elimination-cyclization was carried out under basic conditions with thiourea, methyl thiourea, methyl urea, guanidine hydrochloride, benzamidine hydrochloride and ortho-phenylene diamine. Twenty-three compounds were prepared, and 14 of them were evaluated by the Batrachotoxin (BTX) radioligand binding assay for their binding affinity to neuronal sodium channels. Compound 7c was found to be a potential neuronal sodium channels blocker. 相似文献
7.
In the presence of [Ru(terpyridine)(2,6‐pyridinedicarboxylate)], aliphatic and benzylic alcohols are oxidized to the corresponding aldehydes or ketones with high selectivity by using hydrogen peroxide as the oxidant. There is no need for the addition of co‐catalysts or organic solvents. By applying an optimized reaction protocol, high catalyst productivity (turnover number>10 000) and activity (turnover frequency up to 14 800 h?1) has been achieved. 相似文献
8.
A rapid and reliable high performance liquid chromatographic (HPLC) method for the simultaneous determination of heterocyclic
compounds, namely nicotinic acid, nicotinamide, and 3-cyanopyridine, in industrial effluent is described. A Φ4.6 mm × 150
mm, 5 μm C-18 reversed phase stationery phase, and a methanol-acetonitrile-water tertiary mobile phase (20:20:60 v/v) were
used for separation. The detection wavelength of a diode array (DAD) was set at 216 nm with a bandwidth of 16 nm. Phenol was
used as an internal standard. The regression equations revealed a linear relationship between the concentration of the analytes
injected and the peak area detected by DAD. The limits of detection (S/N = 3) ranged from 0.70 to 1.18 mg L−1, the recoveries ranged from 87% to 102% and the precision expressed as % RSD intra-day and inter-day varied from 0.9 to 3.9
and 1.2 to 5.6, respectively. This method is rapid, sensitive and suitable for the monitoring of nicotinic acid, nicotinamide,
and 3-cyanopyridine in effluent of related pharmaceutical manufacturing plants. 相似文献
9.
Wang X Yu JC Yip HY Wu L Wong PK Lai SY 《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,11(10):2997-3004
A novel metal/semiconductor nanocomposite with catalytic and photocatalytic functions has been prepared. The new material consists of highly dispersed platinum (Pt) nanoparticles embedded in a cubic mesoporous nanocrystalline anatase (meso-nc-TiO2) thin film. The porous thin film possesses a narrow pore-size distribution and a large surface area. The diameter of the Pt cluster can be controlled to below 5 nm, and the high dispersion of these clusters gives rise to catalytic activity for the oxidation of carbon monoxide, an important reaction for automobile exhaust treatment. This novel ordered mesoporous Pt/TiO2 nanoarchitecture is also a promising photochemical material, as demonstrated by the photo-driven killing of Micrococcus lylae cells on the film. 相似文献
10.