全文获取类型
收费全文 | 429篇 |
免费 | 7篇 |
国内免费 | 4篇 |
专业分类
化学 | 228篇 |
晶体学 | 9篇 |
力学 | 6篇 |
数学 | 12篇 |
物理学 | 185篇 |
出版年
2022年 | 5篇 |
2021年 | 9篇 |
2020年 | 8篇 |
2019年 | 9篇 |
2018年 | 7篇 |
2017年 | 12篇 |
2016年 | 8篇 |
2015年 | 8篇 |
2014年 | 16篇 |
2013年 | 13篇 |
2012年 | 26篇 |
2011年 | 27篇 |
2010年 | 24篇 |
2009年 | 28篇 |
2008年 | 21篇 |
2007年 | 20篇 |
2006年 | 7篇 |
2005年 | 13篇 |
2004年 | 12篇 |
2003年 | 4篇 |
2002年 | 4篇 |
2001年 | 6篇 |
2000年 | 2篇 |
1999年 | 2篇 |
1998年 | 2篇 |
1997年 | 5篇 |
1996年 | 9篇 |
1995年 | 18篇 |
1994年 | 6篇 |
1993年 | 4篇 |
1992年 | 3篇 |
1990年 | 2篇 |
1989年 | 6篇 |
1988年 | 7篇 |
1987年 | 8篇 |
1986年 | 3篇 |
1985年 | 10篇 |
1984年 | 3篇 |
1982年 | 7篇 |
1981年 | 5篇 |
1980年 | 3篇 |
1979年 | 5篇 |
1978年 | 7篇 |
1977年 | 7篇 |
1976年 | 4篇 |
1975年 | 5篇 |
1974年 | 6篇 |
1973年 | 5篇 |
1972年 | 2篇 |
1971年 | 2篇 |
排序方式: 共有440条查询结果,搜索用时 31 毫秒
1.
Santosh S. Bhujbal Chawale Bhushankumar G. Kale Mayuri A. 《Journal of Analytical Chemistry》2022,77(4):473-483
Journal of Analytical Chemistry - HPTLC is a widely used tool in standardization of herbs because of its ability to estimate the presence of active components in samples. HPTLC-bioautography is a... 相似文献
2.
Plasma Chemistry and Plasma Processing - The hydrocarbons present in diesel exhaust, although treated as minor pollutants, are equivalent to some of the major pollutants in terms of toxicity,... 相似文献
3.
The influence of humic substances on sorption and methylation processes for inorganic- and organotin species is presented. Four sediment samples from different locations of the Rivers Elbe, Mulde and Spittelwasser, Germany, with different organotin and humic contents were selected to extract the humic and fulvic acids. The various fractions—the original sediment, the humic acid, the fulvic acid and the residual sediment—were analysed for their organotin content. The individual buyltin species show quite different distribution patterns. Monobutyltin is found mostly associated with humic acids. Dibutyltin shows a nonunique behaviour. At low total organotin content, dibutyltin is found bonded to humic and fulvic acids, whereas at high organotin content dibutyltin is distributed more with the residual sediment. Most of the tributyltin remains in the sediment unextracted; only small quantities of it are in the fulvic acid fraction. Tetrabutyltin is only in the humic acid fraction when it binds to humic matter; it mostly remains in the sediment. General observations indicate that ionic butyltin species bind to fulvic acids whereas the non-polar tetrabutyltin is not found in the fulvic acid fractions in any of the samples. The appearance of monomethyl- and dimethyl-tin species in the humic and fulvic acid fractions after the alkaline extraction was surprising. There is a correlation between the humic content of the sample and the formation of methyltin species. Evidence is provided by experiments that humic substances act as methylation agents. 相似文献
4.
Nanocrystalline thin films of copper selenide have been grown on glass and tin doped-indium oxide substrates using chemical method. At ambient temperature, golden films have been synthesized and annealed at 200 °C for 1 h and were examined for their structural, surface morphological and optical properties by means of X-ray diffraction (XRD), scanning electron microscopy and UV-vis spectrophotometry techniques, respectively. Cu2−xSe phase was confirmed by XRD pattern and spherical grains of 30 ± 4 - 40 ± 4 nm in size aggregated over about 130 ± 10 nm islands were seen by SEM images. Effect of annealing on crystallinity improvement, band edge shift and photoelectrochemical performance (under 80 mW/cm2 light intensity and in lithium iodide electrolyte) has been studied and reported. Observed p-type electrical conductivity in copper selenide thin films make it a suitable candidate for heterojunction solar cells. 相似文献
5.
A kinematically correct treatment of the full transition amplitude for many-body hypernuclear production is presented. By an example of (+, K+) reaction, effects of the spin-flip amplitude and its interference with the spin-non-flip amplitude are demonstrated and specified for
12
C.Dedicated to Academician Václav Votruba on the occasion of his eightieth birthday.The discussions with many colleagues are appreciated, in particular those with R. Mach, L. Majling and T. Motoba were of much use. 相似文献
6.
The structures of the lightp-shell hypernuclei \({}_\Lambda ^6 He,{}_\Lambda ^7 Li,{}_\Lambda ^9 Liand{}_\Lambda ^9 Be\) are studied by using a realistic effectiveΛN interaction (YNG), and compared to those with the use of the simple one-range Gaussian (ORG) interaction. The YNG interaction, which simulates theΛNG-matrix for the Nijmegen OBE modelD, is characterized by the inner repulsive core and the density-dependence along with the space-exchange and spin-spin components. The framework we adopt is the microscopic α +x + Λ (x=n, d, t or α) three-cluster model, where nucleon antisymmetrization is exactly treated. The characteristic behaviors ofΛ?x andΛ?(αx) interactions derived from the YNG are displayed and discussed. In spite of the remarkable characteristic of YNG, the calculated energy levels of the four hypernuclei are very similar to those previous obtained by using the simple ORG interaction. The stabilization and contraction of the hypernuclear system due to the glue-like role ofΛ-particle persists in the present calculation, though the repulsive core of theΛN interaction tends to prevent from too much contraction. 相似文献
7.
H. Bandō 《Czechoslovak Journal of Physics》1986,36(8):915-921
The mass number dependence of the total pionic decay rate of hypernuclei is evaluated under the closure approximation by using DDHF single-particle wave functions and taking into account the pion distortion and absorption. The effect ofNN andN correlations are then incorporated and found to give a drastic enhancement especially in heavy hypernuclei. More detailed features are discussed for partial and total decay rates of typical light hypernuclei.Presented at the symposium Mesons and Light Nuclei, Bechyn, Czechoslovakia, May 27–June 1, 1985. 相似文献
8.
A. B. Deshpande S. M. Kale S. L. Kapur 《Journal of polymer science. Part A, Polymer chemistry》1973,11(6):1307-1315
Polymerization of methyl methacrylate has been studied with the chromium acetylacetonate–triisobutyl aluminum catalyst system in benzene medium at 40°C. These studies have been carried out at an Al/Cr ratio of 12 to compare the behavior with the previously studied chromium acetyl acetonate–triethyl aluminum catalyst system. The enhanced yield and gelling of polymer suggests a free-radical mechanism of polymerization. Further, the kinetics of polymerization and the heterotactic structure of polymer as determined by NMR examination have led to confirmation of the freeradical mechanism of polymerization of methyl methacrylate by an excess of triisobutylaluminum in the presence of catalyst complex. 相似文献
9.
We consider Albrecht's theory for Raman scattering of fundamentals in the far and pre-resonance regions. Destructive interferences inherent to the A and B terms augment the conventionally suppressed C term dramatically. Raman excitation profiles for the ν1(a1g) and ν6(e2g fundamentals in benzene can be well fitted with theoretical C-term profiles involving the 1E1u(π-π*) state at 1800 A. 相似文献
10.
Abe K Akagi T Anthony PL Antonov R Arnold RG Averett T Band HR Bauer JM Borel H Bosted PE Breton V Button-Shafer J Chen JP Chupp TE Clendenin J Comptour C Coulter KP Court G Crabb D Daoudi M Day D Dietrich FS Dunne J Dutz H Erbacher R Fellbaum J Feltham A Fonvieille H Frlez E Garvey D Gearhart R Gomez J Grenier P Griffioen KA Hoibraten S Hughes EW Hyde-Wright C Johnson JR Kawall D Klein A Kuhn SE Kuriki M Lindgren R Liu TJ Lombard-Nelsen RM Marroncle J Maruyama T Maruyama XK McCarthy J Meyer W 《Physical review letters》1995,74(3):346-350