全文获取类型
收费全文 | 998篇 |
免费 | 162篇 |
国内免费 | 195篇 |
专业分类
化学 | 877篇 |
晶体学 | 10篇 |
力学 | 36篇 |
综合类 | 1篇 |
数学 | 102篇 |
物理学 | 329篇 |
出版年
2024年 | 4篇 |
2023年 | 27篇 |
2022年 | 35篇 |
2021年 | 53篇 |
2020年 | 64篇 |
2019年 | 51篇 |
2018年 | 38篇 |
2017年 | 61篇 |
2016年 | 57篇 |
2015年 | 61篇 |
2014年 | 80篇 |
2013年 | 100篇 |
2012年 | 112篇 |
2011年 | 102篇 |
2010年 | 59篇 |
2009年 | 56篇 |
2008年 | 63篇 |
2007年 | 57篇 |
2006年 | 43篇 |
2005年 | 39篇 |
2004年 | 35篇 |
2003年 | 23篇 |
2002年 | 40篇 |
2001年 | 13篇 |
2000年 | 13篇 |
1999年 | 5篇 |
1998年 | 4篇 |
1997年 | 2篇 |
1996年 | 5篇 |
1995年 | 3篇 |
1994年 | 6篇 |
1993年 | 7篇 |
1992年 | 5篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1989年 | 3篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1984年 | 3篇 |
1983年 | 3篇 |
1982年 | 5篇 |
1980年 | 2篇 |
1978年 | 2篇 |
1928年 | 2篇 |
排序方式: 共有1355条查询结果,搜索用时 15 毫秒
991.
The Photochemical Study of HSA and BSA with Resonance Light-Scattering and Fluorescence Spectra 总被引:2,自引:0,他引:2
In recent years, people have paid close attention to the physiological harms induced byultraviolet (UV) irradiation. The serum albumin, which constitutes 60% of blood plasma,has very important physiological functions. Therefore, to study their photochemicalreaction is of great significance. The metal ions, little molecules and medicines etcinteracting with HSA or BSA have been reported ','*"', but it has not been repoFted aboutusing RLS to study the photochemical reaction of HSA or BSA.… 相似文献
992.
Guan Y Liu Y Wu W Sun K Li Y Ying P Feng Z Li C 《Langmuir : the ACS journal of surfaces and colloids》2005,21(9):3877-3880
Dibenzodioxin adsorption/desorption on solid surfaces is an important issue associated with the formation, adsorption, and emission of dioxins. Dibenzodioxin adsorption/desorption behaviors on inorganic materials (amorphous/mesoporous silica, metal oxides, and zeolites) were investigated using in situ FT-IR spectroscopy and thermogravimetric (TG) analysis. Desorption temperatures of adsorbed dibenzodioxin are very different for different kinds of inorganic materials: approximately 200 degrees C for amorphous/mesoporous silica, approximately 230 degrees C for metal oxides, and approximately 450 degrees C for NaY and mordenite zeolites. The adsorption of dibenzodioxin can be grouped into three categories according to the red shifts of the IR band at 1496 cm(-1) of the aromatic ring for the adsorbed dibenzodioxin: a shift of 6 cm(-1) for amorphous/mesoporous silica, a shift of 10 cm(-1) for metal oxides, and a shift of 14 cm(-1) for NaY and mordenite, suggesting that the IR shifts are proposed to associated with the strength of the interaction between adsorbed dibenzodioxin and the inorganic materials. It is proposed that the dibenzodioxin adsorption is mainly via the following three interactions: hydrogen bonding with the surface hydroxyl groups on amorphous/mesoporous silica, complexation with Lewis acid sites on metal oxides, and confinement effect of pores of mordenite and NaY with pore size close to the molecular size of dibenzodioxin. 相似文献
993.
A polymeric VIV‐Cd compound, {(NH4)2[(VIVO)2(μ2‐O)(nta)2Cd(H2O)2]·H2O}n (H3nta = nitrilotriacetic acid), has been prepared and characterized by single‐crystal X‐ray diffraction. The compound crystallizes in the monoclinic space group C2/c with a = 17.3760(2) Å, b = 8.0488(1) Å, c = 17.3380(2) Å, β = 107.9690(10)°, V = 2306.55(5) Å3, Z = 4, and R1 = 0.0303 for 1958 observed reflections. The structure exhibits a heterometallic three‐dimensional network formed by polymeric [(VIVO)2(μ2‐O)(nta)2Cd(H2O)2]2? anions. 相似文献
994.
肼溶胶-凝胶法制备高比表面积纳米氮化钛粉体的研究 总被引:1,自引:0,他引:1
以无水肼作氮源, 采用肼溶胶-凝胶技术(HSG)成功地制备了TiN粉体, 研究了不同钛源、处理气氛及焙烧温度对TiN粉体晶化过程的影响, 并对其形成机理进行了讨论. 与氨气氮化法相比, 该方法所需温度低、TiN的粒径小、比表面积大, 并且分散均匀. 相似文献
995.
Paul Müller GRald Bernardinelli Huong Can Godoy-Nguyen Thi 《Helvetica chimica acta》1989,72(7):1627-1638
1H-Cyclopropa[a]naphthalene ( 1a ) is accessible via reduction of the dichloro compound 1c with LiAlH4/AlCl3. Several derivatives of tetrahydrocyclopropa[a]naphthalene were synthesized. However, contrary to their 1,1-dihalogeno analogues, they afforded no cycloproparenes upon attempted aromatization. 相似文献
996.
Gao J Zhang Y Jia G Jiang Z Wang S Lu H Song B Li C 《Chemical communications (Cambridge, England)》2008,(3):332-334
An amphiphilic fluorescent catalyst Q9[EuW10O36] (Q = [(C18H37)2N+ (CH3)2]), assembled in the interface of emulsion systems, was directly imaged by fluorescence microscopy; the catalyst shows high selectivity and activity in the oxidation of alcohols using H2O2 as oxidant and the catalyst can be easily separated and recycled by demulsifying. 相似文献
997.
Muzaffer Özcan 《Journal of Solid State Electrochemistry》2008,12(12):1653-1661
Alternating current (AC) impedance measurements of mild steel/sulfuric acid interface in the absence and in the presence of
various concentrations of cystine (Cys–Cys) have been carried out in the 100 kHz–10 mHz frequency range. The results revealed
that Cys–Cys is a good and effective inhibitor for mild steel corrosion in 0.5 M H2SO4 and its percent inhibition efficiency changes with its concentration. Changes in impedance parameters indicated the adsorption
of Cys–Cys on the mild steel surface, which was verified by scanning electron microscope (SEM) and atomic force microscope
(AFM) photographs. Adsorption of Cys–Cys on mild steel surface was found to obey the Langmuir adsorption isotherm with a standard
free energy of adsorption of −33.2 kJ/mol. Energy gaps for the interactions between mild steel surface and Cys–Cys molecule were found to be close
to each other showing that Cys–Cys owns capacity to behave as both electron donor and electron acceptor. 相似文献
998.
Chaves S Gil M Canário S Jelic R Romão MJ Trincão J Herdtweck E Sousa J Diniz C Fresco P Santos MA 《Dalton transactions (Cambridge, England : 2003)》2008,(13):1773-1782
Two O,S-donor ligands, hydroxythiopyrone and hydroxythiopyridinone derivatives, were developed and studied, as well as the corresponding O,O-derivatives, with a view to their potential pharmacological applications as xanthine oxidase (XO) inhibitors. The biological assays revealed that the O,S-ligands present high inhibitory activity towards XO (nanomolar order, close to that of the pharmaceutical drug allopurinol), in contrast to the corresponding O,O-analogues. Due to the biomedical relevance of this molybdenum-containing enzyme, the corresponding Mo(VI) complexes were studied both in solution and in the solid state, aimed at identifying the source of the biological properties. The solution studies showed that, in comparison with the O,O-analogues, the Mo(VI) complexes with the O,S-ligands present some stabilization, which is even more pronounced for the reduced Mo(IV) species. The crystal structures of the Mo(VI) complexes with the hydroxythiopyrone revealed good flexibility of the coordination modes, with two structural isomers and two polymorphic forms for a mononuclear and a binuclear species, respectively. These results give some support to mechanistic proposals for the XO inhibition involving the interaction of the thione group with the molybdenum cofactor, thus indicating a role of the sulfur atom in the XO inhibition. 相似文献
999.
H2 with low CO concentration is produced via photocatalytic reforming of glucose (as a representative of biomass component) on metal/TiO2 catalyst (metals: Pt, Rh, Ru, Ir, Au, Ni, Cu). It is shown that the loaded metals generally enhance the rate of H2 production, while they depress the CO selectivity. Both H2 production and CO selectivity are strongly dependent on the kind of deposited metals on TiO2. For example, Rh/TiO2 catalyst is found to be most active for H2 production while with the most extremely low CO concentration from the photocatalytic reforming of glucose. 相似文献
1000.
Li Jiatong Jia Wenbao Hei Daqian Yao Zeen Cheng Can Zhao Dong Sun Aiyun 《Journal of Radioanalytical and Nuclear Chemistry》2022,331(2):953-965
Journal of Radioanalytical and Nuclear Chemistry - To address hidden explosive identification in luggage, a luggage detection system was designed based on PGNAA technology in this study. A... 相似文献