全文获取类型
收费全文 | 2136篇 |
免费 | 52篇 |
专业分类
化学 | 1153篇 |
晶体学 | 41篇 |
力学 | 77篇 |
数学 | 543篇 |
物理学 | 374篇 |
出版年
2023年 | 13篇 |
2022年 | 22篇 |
2021年 | 33篇 |
2020年 | 39篇 |
2019年 | 54篇 |
2018年 | 92篇 |
2017年 | 95篇 |
2016年 | 99篇 |
2015年 | 77篇 |
2014年 | 117篇 |
2013年 | 319篇 |
2012年 | 119篇 |
2011年 | 132篇 |
2010年 | 145篇 |
2009年 | 90篇 |
2008年 | 128篇 |
2007年 | 110篇 |
2006年 | 74篇 |
2005年 | 44篇 |
2004年 | 43篇 |
2003年 | 30篇 |
2002年 | 32篇 |
2001年 | 21篇 |
2000年 | 20篇 |
1999年 | 17篇 |
1998年 | 15篇 |
1997年 | 11篇 |
1996年 | 11篇 |
1995年 | 9篇 |
1992年 | 3篇 |
1991年 | 3篇 |
1990年 | 5篇 |
1989年 | 7篇 |
1988年 | 6篇 |
1987年 | 8篇 |
1986年 | 9篇 |
1985年 | 15篇 |
1984年 | 9篇 |
1983年 | 9篇 |
1982年 | 10篇 |
1981年 | 16篇 |
1980年 | 5篇 |
1979年 | 9篇 |
1978年 | 3篇 |
1977年 | 7篇 |
1976年 | 11篇 |
1975年 | 5篇 |
1974年 | 9篇 |
1973年 | 9篇 |
1968年 | 9篇 |
排序方式: 共有2188条查询结果,搜索用时 171 毫秒
51.
F.A. Mikailov E. Başaran E. Şentürk L. Tümbek T.G. Mammadov V.P. Aliev 《Phase Transitions》2013,86(12):1057-1064
The results of measurements of the dielectric constant of TlGaSe2 in temperature range of successive phase transitions are presented. An anomaly in the temperature dependence of the real part of dielectric constant in TlGaSe2 has been observed at about 242?K in addition to anomalies at 115, 108, and also near 65?K as reported in previous publications. The presence of temperature hysteresis effects in temperature interval between 115 and 242?K allowed making a conclusion about possible existence of an incommensurate phase in the mentioned temperature range. A model of succession of the structural phase transitions in TlGaSe2 has been suggested. 相似文献
52.
53.
54.
Firstly, poly[phenyl thiadiazole methacrylamide-co-divinylbenzene-co-2-acrylamido-2-methylpropane sulfonic acid] (PTMAAm-co-DVB-co-AMPS), a new polymer resin was synthesized. This polymer resin was characterized by elemental analyzer, X-ray diffractometer, scanning electron microscope (SEM) and IR spectrometer. The glass column packed with the synthesized polymer resin was used for solid phase extraction (SPE). At the same time, the analytes were separated and preconcentrated from various water, dried vegetables samples and standard reference material (CRM) with SPE and determined by flame atomic absorption spectrometer (FAAS). The experimental conditions of this method such as pH, flow rates of sample, flow rates of eluent, type / concentration / volume of eluent, sample volume and matrix ions were examined. The limits of detection (µg L?1) were calculated (3s) 0.9 for Mn(II), 1.4 for Cd(II), Co(II) and Zn(II), 1.5 for Cr(III), 2.2. for Cu(II), 1.9 for Pb(II),1.5 for Ni(II) and 1.9 for Fe(III) (n = 21). The low relative standard deviation, ≤ 2% (n = 11) and preconcentration factor as 75 for analytes were obtained. 相似文献
55.
Teslima Daşbaşı Serkan Şahan Ahmet Ülgen Şenol Kartal 《International journal of environmental analytical chemistry》2013,93(9):916-929
A rapid and simple on-line method is described for the determination of Au(III) in various samples. The method is based on the sorption of gold(III) on Lewatit MonoPlus TP207 chelating resin including the iminodiacetate group, which is used as sorbent material and packed in a minicolumn. The chemical variables such as the pH of the sample solution, eluent type, interfering ions and concentrations of reagents, and instrumental variables such as sample loading volume, reagents flow rates, and tubing length, which affect the efficiency of the method were studied and optimised. Au(III) was sorbed on the chelating resin, from which it could be eluted with 3 mol L?1 HCl, and then introduced directly to the nebuliser-burner system of FAAS. The limit of detection of the method was 0.2 µg L?1 while the relative standard deviation was <4.0% for 20 µg L?1 Au(III) concentration. The preconcentration factor was found to be 106 while the optimised sample volume was 15.3 mL. The accuracy of the method was verified by analysing the certified reference material. The developed method was applied successfully for the determination of gold in different samples with satisfactory results. 相似文献
56.
57.
58.
Journal of Inclusion Phenomena and Macrocyclic Chemistry - Newly phthalocyanine derivative which carries 2,6-dimethoxyphenoxy bioactive groups as tetrakis from non-peripheral positions of the... 相似文献
59.
For a scalar evolution equation ut = K(t, x, u, ux, . . . , u2m+1) with m ≥ 1, the cohomology space H1,2() is shown to be isomorphic to the space of variational operators and an explicit isomorphism is given. The space of symplectic operators for ut = K for which the equation is Hamiltonian is also shown to be isomorphic to the space H1,2() and subsequently can be naturally identified with the space of variational operators. Third order scalar evolution equations admitting a first order symplectic (or variational) operator are characterized. The variational operator (or symplectic) nature of the potential form of a bi-Hamiltonian evolution equation is also presented in order to generate examples of interest. 相似文献
60.
Structural Chemistry - Metal carbonyl complexes, which have been known as effective catalysts since early days, find use in many fields both directly and indirectly. Although the use of metal... 相似文献