全文获取类型
收费全文 | 7394篇 |
免费 | 1168篇 |
国内免费 | 968篇 |
专业分类
化学 | 5408篇 |
晶体学 | 52篇 |
力学 | 467篇 |
综合类 | 61篇 |
数学 | 844篇 |
物理学 | 2698篇 |
出版年
2024年 | 9篇 |
2023年 | 133篇 |
2022年 | 133篇 |
2021年 | 237篇 |
2020年 | 300篇 |
2019年 | 287篇 |
2018年 | 206篇 |
2017年 | 203篇 |
2016年 | 302篇 |
2015年 | 338篇 |
2014年 | 361篇 |
2013年 | 487篇 |
2012年 | 583篇 |
2011年 | 691篇 |
2010年 | 439篇 |
2009年 | 432篇 |
2008年 | 499篇 |
2007年 | 443篇 |
2006年 | 435篇 |
2005年 | 418篇 |
2004年 | 289篇 |
2003年 | 258篇 |
2002年 | 251篇 |
2001年 | 221篇 |
2000年 | 172篇 |
1999年 | 158篇 |
1998年 | 151篇 |
1997年 | 132篇 |
1996年 | 139篇 |
1995年 | 152篇 |
1994年 | 115篇 |
1993年 | 104篇 |
1992年 | 73篇 |
1991年 | 100篇 |
1990年 | 59篇 |
1989年 | 60篇 |
1988年 | 48篇 |
1987年 | 31篇 |
1986年 | 22篇 |
1985年 | 17篇 |
1984年 | 11篇 |
1983年 | 10篇 |
1982年 | 11篇 |
1981年 | 5篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1976年 | 1篇 |
1966年 | 1篇 |
1957年 | 1篇 |
排序方式: 共有9530条查询结果,搜索用时 15 毫秒
991.
Liquid surface curvature variations in microplate wells due to different liquid surface tension cause significant signal change in spectroscopic measurement using a plate reader with a vertical detecting light beam. The signals have been quantitated and used to develop a method for facile surfactant critical micelle concentration determination. 相似文献
992.
Padhee S Hu Y Niu Y Bai G Wu H Costanza F West L Harrington L Shaw LN Cao C Cai J 《Chemical communications (Cambridge, England)》2011,47(34):9729-9731
We report a new class of peptide mimetics, α-AApeptides, that display broad-spectrum activity against both Gram-negative and Gram-positive bacteria and fungi. With non-hemolytic activity, resistance to protease hydrolysis, and easy sequence programmability, α-AApeptides may emerge as a novel class of antibiotics. 相似文献
993.
Chen H Cai C Liu X Li X Jiang H 《Chemical communications (Cambridge, England)》2011,47(44):12224-12226
Pd-catalysed direct oxidative carbonylation of allylic C-H bonds with carbon monoxide was first described. This new procedure shows that the inherent requirement for a leaving group in the Tsuji-Trost palladium-catalysed allylic carbonylation can be lifted, which provides a new route for accessing more synthetically useful β-enoic acid esters with high regioselectivity. 相似文献
994.
Liu TL He ZL Tao HY Cai YP Wang CJ 《Chemical communications (Cambridge, England)》2011,47(9):2616-2618
A direct and facile synthesis of highly functional 5-aza-spiro[2,4]heptanes, a valuable structural motif for drug discovery, is developed via catalytic asymmetric 1,3-dipolar cycloaddition of cyclopropylidene acetate and azomethine ylides for the first time. 相似文献
995.
Shan Y Hao X Shang X Cai M Jiang J Tang Z Wang H 《Chemical communications (Cambridge, England)》2011,47(12):3377-3379
We applied force spectroscopy based on atomic force microscope (AFM) to demonstrate the possibility of measuring the interaction force between single quantum-dots (QDs) and living cells at single particle level under native conditions. In the force-distance cycle, we recorded the events of cellular uptake of single QDs and single QD detachment from the cell. 相似文献
996.
Li Z Zhang L Wang L Guo Y Cai L Yu M Wei L 《Chemical communications (Cambridge, England)》2011,47(20):5798-5800
An "off-on" Zn(2+) and "on-off" Cu(2+) fluorescent chemosensor C was designed and synthesized. The binding of C and Zn(2+)/Cu(2+) is chemically reversible by the addition of EDTA disodium solution; moreover, the fluorescence emission signal of ZnC decreased with the addition of Cu(2+), demonstrating that ZnC could detect Cu(2+)via metal displacement. 相似文献
997.
998.
999.
Anatase TiO2 nanosheets (TiO2 NS) with dominant (001) facets and TiO2 nanoparticles (TiO2 NP) with dominant (101) facets are fabricated by hydrothermal hydrolysis of Ti(OC4H9)4 in the presence and absence of hydrogen fluoride (HF), respectively. Adsorption of N719 onto the as‐prepared samples from ethanol solutions is investigated and discussed. The adsorption kinetic data are modeled using the pseudo‐first‐order, pseudo‐second‐order, and intraparticle diffusion kinetics equations, and indicate that the pseudo‐second‐order kinetic equation and intraparticle diffusion model can better describe the adsorption kinetics. Furthermore, adsorption equilibrium data of N719 on the as‐prepared samples are analyzed by Langmuir and Freundlich models; this suggests that the Langmuir model provides a better correlation of the experimental data. The adsorption capacities (qmax) of N719 on TiO2 NS at various temperatures, determined using the Langmuir equation, are 65.2 (30 °C), 68.2 (40 °C), and 76.6 (50 °C) mg g−1, which are smaller than those on TiO2 NP, 92.4 (30 °C), 100.0 (40 °C), and 108.2 (50 °C) mg g−1, respectively. The larger adsorption capacities of N719 for TiO2 NP versus NS are attributed to its higher specific surface areas. However, the specific adsorption capacities (qmax/SBET) at various temperatures are 1.5 (30 °C), 1.6 (40 °C), and 1.7 (50 °C) mg m−2 for TiO2 NS, which are otherwise higher than those for NP, 0.9 (30 °C), 1.0 (40 °C), and 1.1 (50 °C) mg m−2, respectively. The larger specific adsorption capacities of N719 for TiO2 NS versus NP are because the (001) surface is more reactive for dissociative adsorption of reactant molecules compared with (101) facets. Notably, the qmax and qmax/SBET for both TiO2 samples increase with increasing temperature, suggesting that adsorption of N719 on the TiO2 surface is an endothermic process, which is further confirmed by the calculated thermodynamic parameters including free energy, enthalpy, and entropy of adsorption process. The present work will provide a new understanding on the adsorption process and mechanism of N719 molecules onto TiO2 NS and NP, and this should be of great importance for enhancing the performance of dye‐sensitized solar cells. 相似文献
1000.
A new environmentally benign and highly efficient catalytic system [pi-C5H5NC16H33]3[PO4(WO3)4]/H2O2/CH3COOC2H5 for the epoxidation of soybean oil displayed excellent activity and high recovery. The change of the catalyst during the reaction was investigated by elemental analysis, FT-IR and 31P NMR. 相似文献