全文获取类型
收费全文 | 8639篇 |
免费 | 985篇 |
国内免费 | 780篇 |
专业分类
化学 | 9642篇 |
晶体学 | 36篇 |
力学 | 69篇 |
综合类 | 78篇 |
数学 | 100篇 |
物理学 | 479篇 |
出版年
2023年 | 66篇 |
2022年 | 136篇 |
2021年 | 148篇 |
2020年 | 331篇 |
2019年 | 235篇 |
2018年 | 221篇 |
2017年 | 217篇 |
2016年 | 336篇 |
2015年 | 397篇 |
2014年 | 408篇 |
2013年 | 664篇 |
2012年 | 812篇 |
2011年 | 498篇 |
2010年 | 404篇 |
2009年 | 429篇 |
2008年 | 421篇 |
2007年 | 537篇 |
2006年 | 455篇 |
2005年 | 424篇 |
2004年 | 418篇 |
2003年 | 477篇 |
2002年 | 274篇 |
2001年 | 193篇 |
2000年 | 179篇 |
1999年 | 185篇 |
1998年 | 150篇 |
1997年 | 172篇 |
1996年 | 169篇 |
1995年 | 180篇 |
1994年 | 143篇 |
1993年 | 142篇 |
1992年 | 184篇 |
1991年 | 84篇 |
1990年 | 54篇 |
1989年 | 69篇 |
1988年 | 41篇 |
1987年 | 25篇 |
1986年 | 28篇 |
1985年 | 16篇 |
1984年 | 23篇 |
1983年 | 9篇 |
1982年 | 11篇 |
1981年 | 7篇 |
1980年 | 11篇 |
1979年 | 8篇 |
1978年 | 6篇 |
1976年 | 2篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1970年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
Antimonide-based superlattices dedicated to the elaboration of opto-electronic devices have been studied by X-ray scattering techniques. In particular, specular and non-specular X-ray reflectometry experiments have been performed on two MBE-samples elaborated with different shutter sequences at the interfaces. The results have shown a limitation of the incorporation of Sb species in the subsequent InAs layer for one of the samples, as expected.Then, a study on a InGaAs-cap layer/(InGaAs/AlAsSb)N superlattice grown on a InGaAs/InP buffer layer by both specular X-ray reflectometry and High resolution X-ray diffraction is reported. In particular, the results have revealed the presence of a highly disturbed thin-layer on top of the MOVPE-made GaInAs, whose presence has been explained by In-concentration modification during the desoxidation procedure at the surface of the MOVPE-made GaInAs.Beside the results on the Sb-based heterostructures, the use of X-ray scattering metrology as a routinely working non-destructive testing method has been emphasized. 相似文献
52.
53.
I. P. Romanova S. G. Fattakhov A. A. Nafikova I. I. Vandyukova R. R. Shagidullin N. M. Azancheev V. S. Reznik O. G. Sinyáshin 《Russian Chemical Bulletin》1998,47(9):1812-1819
The reactions of phosphine derivatives of diallyl isocyanurates with palladium(ii) dichloride lead to the formation of complexes, whose structure, composition, and stability depend on the length of the methylene
chain between the isocyanurate and diphenylphosphine fragments in the ligand. 1,3-Diallyl-5-[5′-(diphenylphosphino)pentyl
and 10′-(diphenyl-phosphino)decyl] isocyanurates with PdCl2 form monomeric L2PdCl2
trans-complexes in which P atoms of the ligands participate in coordination with the metal. 1,3-Diallyl-5-[2′-(diphenylphosphino)ethyl]
isocyanurate with PdCl2 forms a dimeric (LPdCl2)2 complex, which decomposes in a solution to the monomer including solvent molecule into the coordination sphere of the metal.
The reactions of 1,3-diallyl-5-[4′-(diphenylphosphino)butyl] isocyanurate and 1,3-diallyl-5-[6′-(diphenylphosphino)hexyl]
isocyanurate with PdCl2 give monomeric chelate LPdCl2 complexes in which one of the allyl groups of the isocyanurate cycle participates in coordination with the central ion along
with the phosphorus atom.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1859–1865, September, 1998. 相似文献
54.
55.
A new procedure for the simultaneous spectrophotometric determination of Zn(II) and Ni(II) with 1-(2-pyridylazo)-2-naphthol as chromogenic reagent has been developed. It is based on resolution of the mixed spectrum over the wavelength range 530–590 nm by applying a least-squares fitting program to standard spectra from each component. The spectra are recorded at an apparent pH of 5.0, provided by an acetate buffer in a mixed 6040 v/v 2-ethoxyethanol/water medium. The relative standard deviations for determination of 13.7 g of Ni and 31.0 g of Zn were 1.9 and 1.0%, respectively (8 replications). The method has been applied to the analysis of iron surfaces coated with a Zn-Ni alloy. The results are compared with those obtained by atomic-absorption spectrophotometry. 相似文献
56.
我们用X射线荧光光谱滤纸片法分析了古今13铜矿石样品中的铜含量,测量结果与化学法一致。此法不需要铜矿石的标样,而且手续简单,方便,检出限低,灵敏度高,测量结果正确可靠,是分析矿石中单一或几个元素的含量较好的方法之一。 相似文献
57.
58.
59.
60.