全文获取类型
收费全文 | 2582篇 |
免费 | 65篇 |
国内免费 | 9篇 |
专业分类
化学 | 1696篇 |
晶体学 | 26篇 |
力学 | 58篇 |
数学 | 310篇 |
物理学 | 566篇 |
出版年
2023年 | 17篇 |
2022年 | 80篇 |
2021年 | 81篇 |
2020年 | 55篇 |
2019年 | 56篇 |
2018年 | 53篇 |
2017年 | 41篇 |
2016年 | 77篇 |
2015年 | 87篇 |
2014年 | 82篇 |
2013年 | 153篇 |
2012年 | 162篇 |
2011年 | 176篇 |
2010年 | 113篇 |
2009年 | 108篇 |
2008年 | 155篇 |
2007年 | 122篇 |
2006年 | 109篇 |
2005年 | 105篇 |
2004年 | 88篇 |
2003年 | 55篇 |
2002年 | 73篇 |
2001年 | 44篇 |
2000年 | 43篇 |
1999年 | 42篇 |
1998年 | 35篇 |
1997年 | 34篇 |
1996年 | 28篇 |
1995年 | 31篇 |
1994年 | 33篇 |
1993年 | 28篇 |
1992年 | 32篇 |
1991年 | 24篇 |
1990年 | 17篇 |
1989年 | 10篇 |
1988年 | 22篇 |
1987年 | 9篇 |
1986年 | 11篇 |
1985年 | 18篇 |
1984年 | 16篇 |
1983年 | 10篇 |
1982年 | 28篇 |
1981年 | 12篇 |
1980年 | 15篇 |
1978年 | 7篇 |
1977年 | 10篇 |
1976年 | 9篇 |
1975年 | 5篇 |
1974年 | 9篇 |
1973年 | 6篇 |
排序方式: 共有2656条查询结果,搜索用时 10 毫秒
71.
C. Sena M. S. Costa G. A. Cabrera-Pasca R. N. Saxena A. W. Carbonari 《Hyperfine Interactions》2013,215(1-3):105-110
We try to envision that there might be a dark-matter world and neutrinos, especially the right-handed ones, might be coupled directly with dark-matter particles in the dark-matter world. The candidate model would be the extended Standard Model based on SU c (3) × SU L (2) × U(1) × SU f (3) × SU R (2), with the search of the detailed version through the aid of the two working rules, “Dirac similarity principle” and “minimum Higgs hypothesis”. 相似文献
72.
Nathan?Costa Peiwei?Li Yangzi?Xu Jianyu?LiangEmail author Satya?Shivkumar 《Journal of nanoparticle research》2018,20(4):103
Template-assisted nanofabrication is a simple and effective method to produce various nanostructure morphologies by controlling the polymer, solvent, and template characteristics. In this study, the importance of the surface interactions between the solution and the template in controlling the morphology of the nanostructures has been highlighted. Contact angles between various polymer solutions and anodized aluminum oxide (AAO) templates have been determined. The morphology of the resultant nanostructures has been correlated with the measured contact angles between solution and template. It is generally observed that nanorods (diameter of 100–350 nm) are produced at low contact angles, whereas nanotubes (diameter of 200–400 nm) tend to form at high contact angles. Therefore, desired nanostructure morphology for a given application can be obtained by controlling the initial wetting interaction between solution and template. 相似文献
73.
Properties associated with the infrared, Rayleigh, and Raman spectra of the CO(3) molecule are calculated by the Hartree-Fock and M?ller-Plesset perturbation theory methods. Vibrational frequencies and infrared activities are found to be in agreement with the experiment and previous calculations. The values obtained for the Raman spectrum show a very sensitive dependence to the treatment of electron correlation. The OCO wag normal mode, unobserved in the IR experiment, is predicted to have a very small Raman scattering activity. Copyright 2000 Academic Press. 相似文献
74.
75.
Schneider MC Rosa SP Almeida MC Costa C Cella DM 《Micron (Oxford, England : 1993)》2007,38(6):590-598
The chromosome study of five species of the family Elateridae, belonging to the subfamilies Agrypninae and Elaterinae, and the analysis of the cytogenetic data previously recorded for this family permitted the establishment of the main strategies of karyotypic differentiation that has occurred in the elaterids. In Agrypninae, the three species studied (Conoderus fuscofasciatus, Conoderus rufidens, and Conoderus sp.) showed the male karyotype 2n=16+X0. This karyotypic uniformity detected in these Conoderus species has also been shared with other species of the same genus, differing considerably from chromosomal heterogeneity verified in the subfamily Agrypninae. The use of the C-banding technique in C. fuscofasciatus and Conoderus sp. revealed constitutive heterochromatin in the pericentromeric region of the majority of the chromosomes. In C. fuscofasciatus, additional constitutive heterochromatin were also observed in the long arm terminal region of almost all chromosomes. Among the representatives of Elaterinae, the karyotype 2n=18+Xy(p) of Pomachilius sp.2 was similar to that verified in the majority of the Coleoptera species, contrasting with the chromosomal formula 2n=18+X0 detected in Cardiorhinus rufilateris, which is most common in the species of Elaterinae. In the majority of the elaterids, the chromosomal differentiation has frequently been driven by reduction of the diploid number; but, among the four cytogenetically examined subfamilies, there are some differences in relation to the trends of karyotypic evolution. 相似文献
76.
77.
Heloisa Beraldo Ricardo F. F. da Costa Rejane Lima Geraldo M. de Lima Ivana S. Lula Bernard Mahieu 《Phosphorus, sulfur, and silicon and the related elements》2013,188(10):2455-2463
The reaction of tin(IV) tetrachloride with 3-formylpyridine semicarbazone and different 3-formylpyridine thiosemicarbazones produces [Sn(HL)CL 3 ][SnCl 5 ] where HL stands for the neutral ligand. The tin(IV) complexes were characterized using a variety of spectroscopic techniques. Coordination through the pyridine nitrogen occurs in all cases. Solvation studies in DMSO indicated that dissociation of the ligands and their complete replacement by solvent molecules occurs. 相似文献
78.
As part of our program to prepare substituted rtaphthoquinones with potential biological activity1 we have synthetized 6, 7-methyleriedioxy-3-alky 1 lawsones (5a-g) from natural safrole (1) and carboxylic' acids (~50% overall yield). 相似文献
79.
80.
do Nascimento Ticiano Gomes Borges Arthur Luy Tavares Ferreira de Almeida Lara Mendes Ribeiro Êurica Adélia Nogueira Silva Fernanda Geny Calheiros da Costa Silva Valdemir do Nascimento Prata Ana Paula Basílio-Júnior Irinaldo Diniz Goulart Marília Oliveira Fonseca Morilla Demetrius Peireira de Freitas Johnnatan Duarte Aragão Cícero Flávio Soares 《Journal of Thermal Analysis and Calorimetry》2022,147(21):11949-11963
Journal of Thermal Analysis and Calorimetry - This work prepared and characterized microcapsule of Uncaria tomentosa (UT) in order to standardize a spray-dryer Uncaria tomentosa extract. The UT... 相似文献