全文获取类型
收费全文 | 726篇 |
免费 | 18篇 |
国内免费 | 26篇 |
专业分类
化学 | 434篇 |
晶体学 | 20篇 |
力学 | 21篇 |
综合类 | 1篇 |
数学 | 59篇 |
物理学 | 235篇 |
出版年
2022年 | 23篇 |
2021年 | 9篇 |
2020年 | 11篇 |
2019年 | 7篇 |
2018年 | 4篇 |
2017年 | 7篇 |
2016年 | 14篇 |
2015年 | 8篇 |
2014年 | 32篇 |
2013年 | 28篇 |
2012年 | 40篇 |
2011年 | 59篇 |
2010年 | 37篇 |
2009年 | 25篇 |
2008年 | 37篇 |
2007年 | 31篇 |
2006年 | 27篇 |
2005年 | 30篇 |
2004年 | 24篇 |
2003年 | 15篇 |
2002年 | 16篇 |
2001年 | 12篇 |
2000年 | 12篇 |
1999年 | 7篇 |
1998年 | 7篇 |
1997年 | 6篇 |
1996年 | 12篇 |
1995年 | 11篇 |
1994年 | 15篇 |
1993年 | 19篇 |
1992年 | 24篇 |
1991年 | 14篇 |
1990年 | 13篇 |
1989年 | 15篇 |
1988年 | 8篇 |
1987年 | 10篇 |
1986年 | 3篇 |
1985年 | 7篇 |
1984年 | 8篇 |
1983年 | 5篇 |
1982年 | 8篇 |
1981年 | 6篇 |
1980年 | 8篇 |
1979年 | 3篇 |
1978年 | 8篇 |
1977年 | 6篇 |
1976年 | 9篇 |
1975年 | 7篇 |
1974年 | 4篇 |
1937年 | 4篇 |
排序方式: 共有770条查询结果,搜索用时 15 毫秒
41.
42.
43.
Chen C. Y. Kao C. L. Yeh H. C. Li H. T. Wu M. D. Cheng M. J. Li W. J. 《Chemistry of Natural Compounds》2022,58(3):385-386
Chemistry of Natural Compounds - A new ketone, vicamazone (4-(2-butoxyethoxy)-4-methylpentan-2-one) (1), was isolated from the leaves of Victoria amazonica (Nymphaeaceae). The structure of the new... 相似文献
44.
45.
Chemistry of Natural Compounds - A novel cyclopropanoid, 4-(2-(benzo[d][1,3]dioxol-5-yl)cyclopropoxy)-2,6-dimethoxyphenol (1) was isolated from the stems of Cinnamomum osmophloeum (Lauraceae). The... 相似文献
46.
Wei-Jie Ou Chen-Shan Kao Yih-Shing Duh Jing-Ming Hsu 《Journal of Thermal Analysis and Calorimetry》2014,116(3):1111-1116
Thermal instability of lithiated cathode materials with organic carbonate were investigated using DSC. Lithium transition metal oxides of LiFePO4, LiMn2O4, and LiCoO2 were mixed with diethyl carbonate, dimethyl carbonate, ethylene carbonate, ethyl methyl carbonate, and propylene carbonate then dynamically screened to about 500 °C. Curves were acquired and analyzed to determine exothermic onset temperatures and reaction enthalpies. These data for assessing the thermal hazards of lithium-ion batteries under discharged conditions were compared to those data published in the literature. 相似文献
47.
48.
Shyh-Dar Lee Ging-Ho Hsiue Chen-Yu Kao 《Journal of polymer science. Part A, Polymer chemistry》1996,34(1):141-148
Polyacrylic acid (PAA) was grafted onto the surface of silicone rubber membrane (SR) by plasma-induced graft copolymerization (PIP). Ar-plasma was used to activate the surface of SR. Also, a determination was made of the influences of plasma treatment power, pressure, time, grafted copolymerization reaction time, and monomer concentration on polymerization yield. The surface properties of SR were measured by ATR-FTIR, ESCA, and SIMS. In those analyses, the elemental composition and different carbon bindings on the surface of SR were examined by ESCA with the amount of O1s/C1s being approximately 0.7 at 60 s by Ar-plasma treatment (60 W, 200 mtorr). The peroxide group introduced on SR was measured via 1,1-diphenyl-2-picryhydrazyl (DPPH). The optimum amount of peroxide groups was 6.85 × 10−8 mol/cm2 at 60 s of Ar-plasma treatment. The peroxide group (33D peak) was introduced onto the surface of SR by negative spectra of SIMS analysis after SR treatment by Ar-plasma. An increase was obtained in grafted polymerization yield with a region of 5 to 50% (v/v) of acrylic acid aqueous solution. Both sites of polyacrylic acid were detected after staining by toluidine blue O. That is, a homobifunctional membrane was developed via this surface modification method. © 1996 John Wiley & Sons, Inc. 相似文献
49.
Addition of hydrochloric or hydrobromic acid to a solution of potassium permanganate in acetonitrile produced a homogeneous mixture, which is suitable for laboratory chlorination or bromination, respectively. Aromatic compounds more reactive than alkylbenzenes can be chlorinated or brominated without additional catalyst. Alkenes and alkynes give the corresponding vicinal dihaloalkanes and vinyl halides. All reactions complete within two hours under mild condition (25-60 °C) with excellent to moderate yields. 相似文献
50.
The complex permitivity of the amorphous semiconductor Si12Ge10As30Te48 has been measured at frequencies from 1 to 4 GHz and at temperatures from 13 to 42°C. The results show that there is resonace absorption at the resonace frequency of 1.6 GHz corresponding to a relaxation time of 2.45 × 10?9 sec at 20°C, and that this resonance frequency increases with increasing temperature. On the basis of the model that the power loss is due to the transitions of dipoles between their equilibrium positions, the computed results are in good agreement with experimental ones. The size and the possible formation of such dipoles are also discussed. 相似文献