全文获取类型
收费全文 | 442篇 |
免费 | 7篇 |
专业分类
化学 | 283篇 |
晶体学 | 28篇 |
力学 | 8篇 |
数学 | 33篇 |
物理学 | 97篇 |
出版年
2023年 | 2篇 |
2022年 | 9篇 |
2021年 | 8篇 |
2020年 | 4篇 |
2019年 | 4篇 |
2018年 | 2篇 |
2017年 | 3篇 |
2016年 | 13篇 |
2015年 | 7篇 |
2014年 | 18篇 |
2013年 | 24篇 |
2012年 | 48篇 |
2011年 | 36篇 |
2010年 | 29篇 |
2009年 | 27篇 |
2008年 | 30篇 |
2007年 | 30篇 |
2006年 | 22篇 |
2005年 | 18篇 |
2004年 | 11篇 |
2003年 | 10篇 |
2002年 | 8篇 |
2001年 | 7篇 |
2000年 | 6篇 |
1999年 | 3篇 |
1998年 | 6篇 |
1997年 | 2篇 |
1996年 | 7篇 |
1995年 | 2篇 |
1993年 | 1篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1989年 | 7篇 |
1988年 | 5篇 |
1987年 | 3篇 |
1986年 | 6篇 |
1984年 | 4篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1979年 | 3篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1975年 | 4篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1883年 | 1篇 |
排序方式: 共有449条查询结果,搜索用时 15 毫秒
111.
Ana C.F. Ribeiro Victor M.M. Lobo Hugh D. Burrows Artur J.M. Valente Ana M. Amado Abílio J.F.N. Sobral Ana S.N. Teles Cecília I.A.V. Santos Miguel A. Esteso 《Journal of Molecular Liquids》2008,140(1-3):73-77
Numerical values for the mean distance of closest approach of ions, “a”, for lithium salts in aqueous solutions are presented and discussed. These values were obtained from both experimental activity and diffusion coefficients, and estimated by using different theoretical approaches. 相似文献
112.
Silveira PC da Silva LA Tromm PT Scheffer Dda L de Souza CT Pinho RA 《Ultrasonics》2012,52(5):650-654
Introduction
The aim of the study was to evaluate the effects of TPU together with DMSO on oxidative stress parameters after eccentric exercise.Methods
Thirty and six animals were divided in control; eccentric exercise (EE); EE + saline gel 0.9%; EE + TPU 0.8 W/cm2; EE + DMSO gel; EE + TPU + DMSO gel and submitted to one 90-min downhill run (1.0 km h−1). TPU was used 2, 12, 24, 46 h after exercise session and 48 h after the animals were killed and the gastrocnemius muscles were surgically removed. Production of superoxide anion, creatine kinase (CK) levels, lipoperoxidation, carbonylation, and antioxidants enzymes were analyzed.Results
Showed that TPU and gel-DMSO improved muscle healing. Moreover, superoxide anion production, TBARS level and protein carbonyls levels, superoxide dismutase and catalase activity were all decreased in the group TPU plus gel-DMSO.Discussion
Our results show that DMSO is effective in the reduction of the muscular lesion and in the oxidative stress after eccentric exercise only when used with TPU. 相似文献113.
Alessandra Pazini Luis Maqueira Harold C. Avila Felipe M. Valente Rian E. Aderne Davi Back Ricardo Q. Aucélio Marco Cremona Jones Limberger 《Tetrahedron letters》2018,59(31):2994-2999
The synthesis of a phenoxy-benzothiadiazole (BTD) derivative is reported for the first time. This derivative was employed as an intermediate in the obtention of two novel highly fluorescent aryl-phenoxy-BTD dyes. Their photophysical properties were evaluated in solution and the results indicate a strong intramolecular charge transfer (ICT) character in the excited state. The luminophore 3a, possessing a donor-BTD-phenoxide architecture, exhibits superior fluorescence quantum yield (0.67) than the designed acceptor-BTD-phenoxide dye (0.06). After electrochemical and photoluminescence characterization of thin films of 3a, an OLED with the configuration ITO/PEDOT:PSS/3a/TPBi/LiF/Al was constructed. This device displayed a green emission centered at 547?nm, with CIE coordinates of (0.40, 0.55). For comparison, an OLED using a previously reported luminescent BTD-pyridyl derivative was also constructed. The OLED made with the phenoxy-BTD derivative operated using less current density and led to higher irradiance and electrical stability, indicating the high potential of ArO-BTD dyes for future application in electroluminescent devices. 相似文献
114.
Isoprene–Styrene Chain Shuttling Copolymerization Mediated by a Lanthanide Half‐Sandwich Complex and a Lanthanidocene: Straightforward Access to a New Type of Thermoplastic Elastomers 下载免费PDF全文
Dr. Andreia Valente Dr. Gregory Stoclet Dr. Fanny Bonnet Prof. André Mortreux Prof. Marc Visseaux Prof. Philippe Zinck 《Angewandte Chemie (International ed. in English)》2014,53(18):4638-4641
A lanthanide half‐sandwich complex and a ansa lanthanidocene have been assessed for isoprene–styrene chain shuttling copolymerization with n‐butylethylmagnesium (BEM). In the presence of 1 equiv BEM, a fully amorphous multiblock microstructure of soft and hard segments is achieved. The microstructure consists of poly(isoprene‐co‐styrene) blocks, with hard blocks rich in styrene and soft blocks rich in isoprene. The composition of the blocks and the resulting glass transition temperatures (Tg) can be easily modified by changing the feed and/or the relative amount of the catalysts, highlighting a new class of thermoplastic elastomers (TPEs) with tunable transition temperatures. The materials self‐organize into nanostructures in the solid state. 相似文献
115.
H. J. M. Bowen E. Page I. Valente R. J. Wade 《Journal of Radioanalytical and Nuclear Chemistry》1979,48(1-2):9-16
Radio-tracer experiments have shown that antimony, mercury and zinc interact to form complexes with humic and/or fulvic acids,
whose molar masses can be estimated by gel chromatography. Sb(III) and (V) humates are stable in the pH range 7–11, but are
largely dissociated below pH 4; humic acid does not reduce Sb(V) to Sb(III) in solution. Mercury forms a strong complex with
humic+fulvic acids. Zinc forms complexes with both humic acids and glycine, and the humic acid complex has similar elution
behaviour on dextran gel to a fraction from river water equilibrated with65Zn. At least one other form of zinc, in addition to Zn2+, occurs in this river. 相似文献
116.
Critical behavior in La0.7Pb0.05Na0.25MnO3 has been investigated by dc magnetization measurements. Magnetic data indicate that the compound exhibits a continuous (second-order) paramagnetic (PM) to ferromagnetic (FM) phase transition. Estimates of critical exponents yield δ=4.80±0.01, γ=1.296±0.002 and β=0.344±0.007 (consistent with both the predictions for the three-dimensional-Heisenberg model and with those reported for materials when the FM transition is ascribed to the double exchange (DE) mechanism as a major origin) with TC=334.54±0.08. The critical exponent γ is slightly inferior than predicted from the 3D Heisenberg model. Such a difference may be due, within the context of the quenched disorder, to the presence of some alterations of short-range magnetic order of FM clusters in the PM phase. The temperature variation in the effective exponent (γeff) is similar to those for disordered ferromagnets. 相似文献
117.
118.
119.
120.