全文获取类型
收费全文 | 1173篇 |
免费 | 28篇 |
国内免费 | 5篇 |
专业分类
化学 | 640篇 |
晶体学 | 59篇 |
力学 | 70篇 |
数学 | 191篇 |
物理学 | 246篇 |
出版年
2021年 | 14篇 |
2020年 | 13篇 |
2019年 | 14篇 |
2018年 | 9篇 |
2016年 | 16篇 |
2015年 | 25篇 |
2014年 | 18篇 |
2013年 | 33篇 |
2012年 | 44篇 |
2011年 | 54篇 |
2010年 | 28篇 |
2009年 | 22篇 |
2008年 | 44篇 |
2007年 | 42篇 |
2006年 | 55篇 |
2005年 | 47篇 |
2004年 | 25篇 |
2003年 | 26篇 |
2002年 | 34篇 |
2001年 | 18篇 |
2000年 | 24篇 |
1999年 | 13篇 |
1998年 | 20篇 |
1997年 | 12篇 |
1996年 | 19篇 |
1995年 | 16篇 |
1994年 | 28篇 |
1993年 | 18篇 |
1992年 | 31篇 |
1991年 | 17篇 |
1990年 | 27篇 |
1989年 | 23篇 |
1988年 | 21篇 |
1987年 | 18篇 |
1986年 | 10篇 |
1985年 | 22篇 |
1984年 | 31篇 |
1983年 | 19篇 |
1982年 | 17篇 |
1981年 | 14篇 |
1980年 | 14篇 |
1979年 | 14篇 |
1978年 | 14篇 |
1977年 | 21篇 |
1976年 | 13篇 |
1975年 | 15篇 |
1974年 | 19篇 |
1973年 | 25篇 |
1972年 | 9篇 |
1943年 | 7篇 |
排序方式: 共有1206条查询结果,搜索用时 15 毫秒
51.
52.
Different inner-sphere coordination environments are observed for the uranyl nitrate complexes formed with octyl-phenyl-N,N-diisobutylcarbamoylmethylphosphine oxide and tributyl phosphate in dodecane and in the hydrophobic ionic liquids (ILs) [C(4)mim][PF(6)] and [C(8)mim][N(SO(2)CF(3))(2)]. Qualitative differences in the coordination environment of the extracted uranyl species are implied by changes in peak intensity patterns and locations for uranyl UV-visible spectral bands when the solvent is changed. EXAFS data for uranyl complexes in dodecane solutions is consistent with hexagonal bipyramidal coordination and the existence of UO(2)(NO(3))(2)(CMPO)(2). In contrast, the complexes formed when uranyl is transferred from aqueous nitric acid solutions into the ILs exhibit an average equatorial coordination number of approximately 4.5. Liquid/liquid extraction results for uranyl in both ILs indicate a net stoichiometry of UO(2)(NO(3))(CMPO)(+). The concentration of the IL cation in the aqueous phase increases in proportion to the amount of UO(2)(NO(3))(CMPO)(+) in the IL phase, supporting a predominantly cation exchange mechanism for partitioning in the IL systems. 相似文献
53.
Gary L. Guillet Skyler L. Pitts Kirkland W. Sheriff Donna N. Rucker Aaryn L. Rogers 《Acta Crystallographica. Section C, Structural Chemistry》2019,75(10):1381-1388
A novel family of four 1‐bromo‐2,6‐bis{[(λ5‐phosphanylidene)imino]methyl}benzene ligands has been synthesized and characterized. The phosphiniminomethyl substituents are decorated with either three phenyl groups, two phenyl and one cyclohexyl group, one phenyl and two cyclohexyl groups, or three cyclohexyl groups. Each ligand was metallated using zero‐valent nickel through an oxidative addition to form a family of organonickel(II) complexes, namely (2,6‐bis{[(triphenyl‐λ5‐phosphanylidene)imino]methyl}phenyl‐κ3N,C1,N′)bromidonickel(II) dichloromethane hemisolvate, [NiBr(C44H37N2P2)]·0.5CH2Cl2, (2,6‐bis{[(cyclohexyldiphenyl‐λ5‐phosphanylidene)imino]methyl}phenyl‐κ3N,C1,N′)bromidonickel(II) diethyl ether hemisolvate, [NiBr(C44H49N2P2)]·0.5C4H10O, (2,6‐bis{[(dicyclohexylphenyl‐λ5‐phosphanylidene)imino]methyl}phenyl‐κ3N,C1,N′)bromidonickel(II), [NiBr(C44H61N2P2)], and (2,6‐bis{[(tricyclohexyl‐λ5‐phosphanylidene)imino]methyl}phenyl‐κ3N,C1,N′)bromidonickel(II), [NiBr(C44H73N2P2)]. This family of complexes represents a useful opportunity to investigate the impact of incrementally changing the steric characteristics of a complex on its structure and reactivity. 相似文献
54.
Menard E Bilhaut L Zaumseil J Rogers JA 《Langmuir : the ACS journal of surfaces and colloids》2004,20(16):6871-6878
Nanotransfer printing represents an additive approach for patterning thin layers of solid materials with nanometer resolution. The surface chemistries, thin film deposition techniques, and stamp designs are all important for the proper operation of this method. This paper presents some details concerning processing procedures and other considerations needed for patterning two- and three-dimensional nanostructures with low density of defects and minimal distortions. 相似文献
55.
PD McCrary PA Beasley SP Kelley S Schneider JA Boatz TW Hawkins JP Perez BW McMahon M Pfiel SF Son SL Anderson RD Rogers 《Physical chemistry chemical physics : PCCP》2012,14(38):13194-13198
The passivation and stability of suspensions of titanium nanoparticles in azolium azolate ionic liquids can be tuned by introducing metal specific binding sites in the azolate anion. 相似文献
56.
Clifton LA Sanders MR Castelletto V Rogers SE Heenan RK Neylon C Frazier RA Green RJ 《Physical chemistry chemical physics : PCCP》2011,13(19):8881-8888
The self-assembly in solution of puroindoline-a (Pin-a), an amphiphilic lipid binding protein from common wheat, was investigated by small angle neutron scattering, dynamic light scattering and size exclusion chromatography. Pin-a was found to form monodisperse prolate ellipsoidal micelles with a major axial radius of 112 ± 4.5 ? and minor axial radius of 40.4 ± 0.18 ?. These protein micelles were formed by the spontaneous self-assembly of 38 Pin-a molecules in solution and were stable over a wide pH range (3.5-11) and at elevated temperatures (20-65 °C). Pin-a micelles could be disrupted upon addition of the non-ionic surfactant dodecyl-β-maltoside, suggesting that the protein self-assembly is driven by hydrophobic forces, consisting of intermolecular interactions between Trp residues located within a well-defined Trp-rich domain of Pin-a. 相似文献
57.
Amaresh RR Lakshmikantham MV Baldwin JW Cava MP Metzger RM Rogers RD 《The Journal of organic chemistry》2002,67(8):2453-2458
3,4-Cyanomethyl substituted thiophenes reacted with thionyl chloride in the presence of base to give dicyano substituted thieno(3,4-c)thiophenes. The use of selenium oxychloride furnished the corresponding cyano substituted seleno(3,4-c)thiophene. 1,2-Phenylenediacetonitriles gave the corresponding cyano substituted benzo(c)thiophenes and benzo(c)selenenophenes, respectively, upon reaction with thionyl chloride and selenium oxychloride in the presence of base. 相似文献
58.
59.
60.
D'Souza F Rogers LM O'Dell ES Kochman A Kutner W 《Bioelectrochemistry (Amsterdam, Netherlands)》2005,66(1-2):35-40
Two different fullerene film-modified electrodes were prepared and used for surface immobilization and electrochemical property investigation of horse heart cytochrome c (cyt c). Both a pristine fullerene film and fullerene-palladium (C(60)-Pd) polymer film-modified platinum, glassy carbon and indium-tin-oxide (ITO) electrodes were used. The immobilized cyt c was characterized by piezoelectric microgravimetry at a quartz crystal microbalance (QCM), UV-visible absorption, and X-ray photoelectron spectroscopy (XPS), as well as cyclic voltammetry (CV) techniques. The UV-visible spectral studies revealed a small blue shift of both the Soret and Q band of the heme moiety of cyt c, immobilized on the C(60)-Pd polymer film-modified ITO electrode, as compared to the bands of cyt c in solution suggesting that molecules of cyt c are densely packed onto the surface of the modified electrode. The CV studies revealed a quasi-reversible electrode behavior of the heme moiety indicating the occurrence of kinetically hindered electron transfer. A good agreement was found between the values of cyt c electrode surface coverage determined by piezoelectric microgravimetry and cyclic voltammetry. For piezoelectric microgravimetry, these values ranged from 0.5 x 10(-10) to 2.5 x 10(-10) mol cm(-2), depending upon the amount of cyt c present in solution and the time allowed for immobilization, which compared with a value of 3.6+/-0.4 x 10(-10) mol cm(-2) determined by CV. The possible mechanisms of cyt c immobilization on the C(60) film and C(60)-Pd film-modified electrodes are also discussed. 相似文献