全文获取类型
收费全文 | 11693篇 |
免费 | 2024篇 |
国内免费 | 1479篇 |
专业分类
化学 | 11693篇 |
晶体学 | 207篇 |
力学 | 113篇 |
综合类 | 38篇 |
数学 | 310篇 |
物理学 | 2835篇 |
出版年
2024年 | 82篇 |
2023年 | 187篇 |
2022年 | 616篇 |
2021年 | 614篇 |
2020年 | 968篇 |
2019年 | 684篇 |
2018年 | 528篇 |
2017年 | 459篇 |
2016年 | 751篇 |
2015年 | 710篇 |
2014年 | 698篇 |
2013年 | 971篇 |
2012年 | 688篇 |
2011年 | 649篇 |
2010年 | 503篇 |
2009年 | 541篇 |
2008年 | 516篇 |
2007年 | 561篇 |
2006年 | 480篇 |
2005年 | 372篇 |
2004年 | 367篇 |
2003年 | 361篇 |
2002年 | 887篇 |
2001年 | 277篇 |
2000年 | 203篇 |
1999年 | 177篇 |
1998年 | 203篇 |
1997年 | 141篇 |
1996年 | 114篇 |
1995年 | 100篇 |
1994年 | 98篇 |
1993年 | 60篇 |
1992年 | 78篇 |
1991年 | 55篇 |
1990年 | 69篇 |
1989年 | 55篇 |
1988年 | 35篇 |
1987年 | 20篇 |
1986年 | 48篇 |
1985年 | 30篇 |
1984年 | 34篇 |
1983年 | 21篇 |
1982年 | 22篇 |
1981年 | 32篇 |
1980年 | 17篇 |
1979年 | 26篇 |
1978年 | 15篇 |
1977年 | 16篇 |
1976年 | 18篇 |
1973年 | 14篇 |
排序方式: 共有10000条查询结果,搜索用时 125 毫秒
31.
32.
33.
Results of two urgent and practically important directions of research on the indirect oxidation of organic compounds by highly reactive intermediates generated electrochemically from oxygen (HO2
–, HO2
·, HO·) are considered and orderly arranged. The studies in question are the indirect synthesis and mineralization of organic toxicants in waste water. 相似文献
34.
S.V.N Bhaskara Rao T.K. Balasubramanian 《Journal of Quantitative Spectroscopy & Radiative Transfer》2004,87(2):203-210
Fresh computations of rovibrational matrix elements of the polarizability α[=(α||+2α⊥)/3] and the polarizability anisotropy γ(=α||−α⊥) of the heteronuclear isotopomers, HD, HT, and DT, of the hydrogen molecule are presented. The computations combine the most accurate polarizability functions α(R) and γ(R) (R being the bond distance) on the one hand and the most accurate adiabatic potential on the other. The calculations are extended to the product operators xα and xγ where x is the centre of mass to centre of charge separation in the heteronuclear species. The latter matrix elements are needed, additionally, for elucidating the absorption intensities of some of the zero-phonon rovibrational transitions peculiar to the heteronuclear species in the crystalline phase. 相似文献
35.
报道了硅基有机微腔的电致发光(EL).该微腔由上半透明金属膜、中心有源多层膜和多孔硅分布Bragg反射镜(PS DBR)组成.半透明金属膜由Ag(20nm)构成,充当发光器件的负电极和微腔的上反射镜.有源多层膜由Al (1 nm) / LiF(05 nm) /Alq3/Alq3:DCJTB/NPB/CuPc/ITO/SiO2组成,其中的Al/LiF为电子注入层,ITO为正电极,SiO2为使正、负电极电隔离的介质层.该PS DBR是采用设备简单、成本低廉且非常省时的电化学腐蚀法用单晶Si来制备的;该PS
关键词:
电化学腐蚀
电致发光
窄峰发射
硅基有机微腔 相似文献
36.
S. Mancini D. Vitali V. Giovannetti P. Tombesi 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,22(3):417-422
We show that the optomechanical coupling between an optical cavity mode and two movable cavity mirrors is able to entangle
two different macroscopic oscillation modes of the mirrors. This continuous variable entanglement is maintained by the light
bouncing between the mirrors and is robust against thermal noise. In fact, it could be experimentally demonstrated using present
technology.
Received 2 September 2002 / Received in final form 10 October 2002 Published online 7 January 2003 相似文献
37.
制作了掺杂rubrene和4-(dicyanomethylene)-2-t-butyl-6-(1,1,7,7-tetramethyljulolidyl-9,enyl)-4H-pyran(DCJTB)两种荧光染料的红光有机电致发光器件。N,N’-diphenyl-N,N’-bis(1-naphthyl)-(1,1’-biphenyl)-4,4’-diamine(NPB)和掺杂的Tri-(8-hydroxyquinoline)aluminum(Alq3)分别作为空穴和电子传输层。我们发现掺rubrene和DCJTB的器件性能与只掺DCJTB的器件性能相比有所提高。器件性能的改善是因为掺入的rubrene能够促进从Alq3到DCJTB的能量转移。根据荧光衰减曲线,计算出从Alq3到DCJTB、从Alq3到rubrene以及从rubrene到DCJTB的能量转移速率分别为1.04×109,3.89×109,2.79×109s-1。可以看出能量通过rubrene从Alq3到DCJTB的转移速率是能量直接从Alq3到DCJTB的2.7倍。 相似文献
38.
K. K. Turgunov B. Tashkhodzhaev L. V. Molchanov Kh. M. Shakhidoyatov 《Journal of Structural Chemistry》2004,45(5):912-916
The structure of bis-(2,3-pentamethylene-3,4-dihydro-4-oxoquinazolinium) tetrachlorocuprate (II) sesquihydrate, (C13H15N2O)2[CuCl4]·1.5H2O, was determined by single crystal X-ray diffraction. In contrast to the previously studied analogs, the compound contains crystallization water molecules.Original Russian Text Copyright © 2004 by K. K. Turgunov, B. Tashkhodzhaev, L. V. Molchanov, and Kh. M. Shakhidoyatov__________Translated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 5, pp. 955–959, September–October, 2004. 相似文献
39.
Jie Da Thieo E. Hogen‐Esch 《Journal of polymer science. Part A, Polymer chemistry》2004,42(2):360-373
The synthesis is reported of copolymers of N,N‐dimethylacrylamide (DMA) and methacrylates containing 2,2′‐dihydroperfluorodecanoyl (RF) groups separated from the methacrylate by long polyethylene glycol (PEG) tether groups (between 1000 and 14,000 Da). At concentrations of between 1 and 8 wt % the copolymers with macromonomer contents of 1 mol % or less give gels in organic solvents such as dioxane, THF, or methanol, as well as in water. Given the low molecular weights, this indicates very efficient association of very low numbers of RF groups. Association and gel formation is enormously enhanced in the presence of longer PEG tethers. This is consistent with smaller poly(N,N,‐dimethylacrylamide) (PDMA) intermolecular excluded volume effects that are mediated by the longer PEG tethers and possibly by the incompatibility of PEG and PDMA that may lead to the formation of PEG microdomains. This increases the local concentrations of the RF groups in the PEO domains that are not diluted by the PDMA chains, as would be the case in the absence of PEG tethers. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 360–373, 2004 相似文献
40.
Madhuchhanda Maiti Susmita Sadhu Anil K. Bhowmick 《Journal of Polymer Science.Polymer Physics》2004,42(24):4489-4502
In this work, preparation and properties of different nanoclays modified by organic amines (octadecyl amine, a primary amine, and hexadecyltrimethylammonium bromide, a tertiary amine) and brominated polyisobutylene‐co‐paramethylstyrene (BIMS)‐clay nanocomposites are reported. The clays and the rubber nanocomposites have been characterized with the help of Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and X‐ray diffraction (XRD). The X‐ray diffraction peaks observed in the range of 3 °–10 ° for the modified clays disappear in the rubber nanocomposites. TEM photographs show predominantly exfoliation of the clays in the range of 12 ± 4 nm in the BIMS. In the FTIR spectra of the nanocomposites, there are common peaks of virgin rubber as well as those of the clays. Excellent improvement in mechanical properties like tensile strength, elongation at break, and modulus is observed on incorporation of the nanoclays in the BIMS. Structure‐property correlation in the above nanocomposites is attempted. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 4489–4502, 2004 相似文献