全文获取类型
收费全文 | 470篇 |
免费 | 40篇 |
国内免费 | 3篇 |
专业分类
化学 | 389篇 |
晶体学 | 10篇 |
力学 | 14篇 |
数学 | 40篇 |
物理学 | 60篇 |
出版年
2022年 | 6篇 |
2021年 | 5篇 |
2020年 | 5篇 |
2019年 | 11篇 |
2018年 | 10篇 |
2017年 | 7篇 |
2016年 | 19篇 |
2015年 | 18篇 |
2014年 | 15篇 |
2013年 | 13篇 |
2012年 | 20篇 |
2011年 | 34篇 |
2010年 | 19篇 |
2009年 | 18篇 |
2008年 | 36篇 |
2007年 | 39篇 |
2006年 | 29篇 |
2005年 | 31篇 |
2004年 | 18篇 |
2003年 | 21篇 |
2002年 | 11篇 |
2001年 | 4篇 |
2000年 | 3篇 |
1999年 | 4篇 |
1998年 | 9篇 |
1997年 | 8篇 |
1996年 | 5篇 |
1995年 | 4篇 |
1994年 | 3篇 |
1992年 | 5篇 |
1990年 | 6篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1981年 | 4篇 |
1980年 | 6篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1974年 | 6篇 |
1973年 | 4篇 |
1972年 | 2篇 |
1971年 | 3篇 |
1965年 | 3篇 |
1963年 | 2篇 |
1960年 | 2篇 |
1959年 | 4篇 |
1958年 | 3篇 |
1957年 | 6篇 |
排序方式: 共有513条查询结果,搜索用时 15 毫秒
61.
62.
63.
Juan Chen Stepan Stepanovic Dr. Apparao Draksharapu Prof. Dr. Maja Gruden Prof. Dr. Wesley R. Browne 《Angewandte Chemie (International ed. in English)》2018,57(12):3207-3211
Non‐heme (L)FeIII and (L)FeIII‐O‐FeIII(L) complexes (L=1,1‐di(pyridin‐2‐yl)‐N,N‐bis(pyridin‐2‐ylmethyl)ethan‐1‐amine) underwent reduction under irradiation to the FeII state with concomitant oxidation of methanol to methanal, without the need for a secondary photosensitizer. Spectroscopic and DFT studies support a mechanism in which irradiation results in charge‐transfer excitation of a FeIII?μ‐O?FeIII complex to generate [(L)FeIV=O]2+ (observed transiently during irradiation in acetonitrile), and an equivalent of (L)FeII. Under aerobic conditions, irradiation accelerates reoxidation from the FeII to the FeIII state with O2, thus closing the cycle of methanol oxidation to methanal. 相似文献
64.
Two new polyketides, pestalotiotones A (1) and B (2) were isolated from the cultured broth of Pestalotiopsis sp. FT172. The structures of compounds 1 and 2 were determined by analysis of HRMS and NMR spectroscopic data. The absolute configurations of compound 1 were assigned by Mosher reaction, J-based configuration analysis, and DP4 NMR calculations. Both compounds were tested against cancer cell lines, pathogenic fungi and bacteria. 相似文献
65.
Heats of formation of rate-earth monosulfate complexes have been measured calorimetrically for the ions La3+, Sm3+, Tb3+, and Er3+, in D2O and H2O solvents. Within the limits of experimental error there is no evidence for a solvent isotope effect on the heat and entropy changes of these complexation reactions.This paper was abstracted from W.D.W.'s Ph.D. dissertation, May 1973. 相似文献
66.
Zhou Q Henderson WA Appetecchi GB Montanino M Passerini S 《The journal of physical chemistry. B》2008,112(43):13577-13580
Two ionic liquids based upon N-alkyl-N-methylpyrrolidinium cations (PY(1R)(+)) (R=3 for propyl or 4 for butyl) and the bis(fluorosulfonyl)imide (FSI(-)), N(SO2F)2(-), anion have been extensively characterized. The ionic conductivity and viscosity of these materials are found to be among the highest and lowest, respectively, reported for aprotic ionic liquids. Both ionic liquids crystallize readily on cooling and undergo several solid-solid phase transitions on heating prior to melting. PY13FSI and PY14FSI are found to melt at -9 and -18 degrees C, respectively. The thermal stability of PY13FSI and PY14FSI is notably lower than for the analogous salts with the bis(trifluoromethanesulfonyl)imide (TFSI(-)), N(SO2CF3)2(-), anion. Both ionic liquids have a relatively wide electrochemical stability window of approximately 5 V. 相似文献
67.
Covalent attachment of the enzymes glucose oxidase and catalase to carbon nanotubes enables the tandem catalytic conversion of glucose and H(2)O(2) formed to power autonomous movement of the nanotubes. 相似文献
68.
Unimolecular binary half-adders with orthogonal chemical inputs 总被引:1,自引:0,他引:1
Unimolecular half-adders based upon an arylvinyl-bipyridyl fluorophore platform were demonstrated where all the chemical input combinations were fully processed by half-adder molecules to generate the arithmetic results of the entire truth table. 相似文献
69.
Copper (I) guanidinate dimers were generated by a salt metathesis route and structurally characterized. The guanidinates differed from the known amidinate dimers because of a large torsion of the dimer ring. This had a direct effect on their thermal chemistry. The thermal reactivity was investigated by several methods, including a novel temperature-resolved, gas-phase method that was monitored by mass spectrometry. The copper guanidinates underwent carbodiimide deinsertion to produce copper metal at temperatures between 225 -and 250 degrees C in the gas phase and at 125 degrees C in solution. The amidinate investigated also showed copper deposition at 190 degrees C in the gas phase, and 135 degrees C in solution, but without carbodiimide deinsertion. The guanidinate compounds deposited crystalline copper at 225 degrees C in a simple chemical vapor deposition experiment. 相似文献
70.
The molecular structure of sodium ethylmercury thiosalicylate (also known as thimerosal and Merthiolate) and related arylthiolate mercury alkyl compounds, namely PhSHgMe and PhSHgEt, have been determined by single crystal X-ray diffraction. (1)H NMR spectroscopic studies indicate that the appearance of the (199)Hg mercury satellites of the ethyl group of thimerosal is highly dependent on the magnetic field and the viscosity of the solvent as a consequence of relaxation due to chemical shift anisotropy. 相似文献