全文获取类型
收费全文 | 7175篇 |
免费 | 315篇 |
国内免费 | 80篇 |
专业分类
化学 | 4273篇 |
晶体学 | 221篇 |
力学 | 193篇 |
综合类 | 4篇 |
数学 | 1051篇 |
物理学 | 1828篇 |
出版年
2022年 | 67篇 |
2021年 | 66篇 |
2020年 | 93篇 |
2019年 | 141篇 |
2018年 | 100篇 |
2017年 | 98篇 |
2016年 | 142篇 |
2015年 | 122篇 |
2014年 | 189篇 |
2013年 | 562篇 |
2012年 | 313篇 |
2011年 | 356篇 |
2010年 | 239篇 |
2009年 | 212篇 |
2008年 | 247篇 |
2007年 | 253篇 |
2006年 | 219篇 |
2005年 | 176篇 |
2004年 | 173篇 |
2003年 | 202篇 |
2002年 | 171篇 |
2001年 | 100篇 |
2000年 | 94篇 |
1999年 | 66篇 |
1997年 | 70篇 |
1996年 | 79篇 |
1995年 | 86篇 |
1994年 | 82篇 |
1993年 | 84篇 |
1992年 | 98篇 |
1991年 | 89篇 |
1990年 | 76篇 |
1989年 | 110篇 |
1988年 | 76篇 |
1987年 | 70篇 |
1986年 | 81篇 |
1985年 | 126篇 |
1984年 | 119篇 |
1983年 | 93篇 |
1982年 | 98篇 |
1981年 | 101篇 |
1980年 | 85篇 |
1979年 | 98篇 |
1978年 | 74篇 |
1977年 | 101篇 |
1976年 | 79篇 |
1975年 | 86篇 |
1974年 | 92篇 |
1973年 | 97篇 |
1972年 | 57篇 |
排序方式: 共有7570条查询结果,搜索用时 46 毫秒
991.
A. Baldacci V. Malathy Devi Da-Wun Chen K. Narahari Rao B. Fridovich 《Journal of Molecular Spectroscopy》1978,70(1):143-159
The absorption spectrum of carbon dioxide has been recorded in the wavenumber region 2395-2216 cm?1 with a spectral resolution between 0.02 and 0.03 cm?1. About twenty transitions have been identified and the molecular constants of the levels involved have been evaluated. In view of the interest of this region in atmospheric studies a map of the entire spectrum recorded by using a normal sample of carbon dioxide is presented including the identifications for the different bands. About 90% of the lines observed have been interpreted. Some of them have been assigned to transitions originating from higher excited states of 12C16O2 not considered before in interpreting this spectral region. For the first time, bands of 12C16O17O have been identified in the 4.3-μm spectra obtained with the natural sample. 相似文献
992.
Pushpa M. Rao A. Venugopalan S.A. Ahmad G.D. Saksena 《Spectrochimica Acta Part B: Atomic Spectroscopy》1985,40(8):1059-1066
Isotope shifts ΔT (170-166) have been evaluated for 54 even and 94 odd energy levels covering almost all the known configurations of the neutral erbium. These ΔT values have been derived from the isotope shift measurements carried out in 159 lines in the region 3900–4605 A using a Fabry-Perot spectrometer and liquid-air-cooled hollow cathode source with highly enriched 170Er and 166Er isotopic samples. Electronic configurations assigned to energy levels of Er I by earlier workers have been mostly confirmed and in few cases revisions have been suggested on the basis of observed ΔT values. Probable configurations have been also suggested for unassigned levels of Er I, and a large number of even levels could be assigned to 4f11 5d 6s 6p configuration. 相似文献
993.
A few halo, nitro and methoxy substituted 1:2-naphthoquinones with the substituents in both the benzenoid and the quinonoid rings have been synthesised and evaluated for their fungistatic properties. Among the quinonoid compounds tested 3:4-dichloro-1:2-naphthoquinones exhibited the highest activity. 相似文献
994.
995.
996.
The second negative bands of O 2 + , lying in the region 5000–1850 Å, have been photographed using oxygen enriched in18O. A study of the isotope shifts in the band heads revealed that thev″ numbering is to be increased by one unit whereas thev′ numbering remains unaltered. This change in vibrational numbering leads to a revision of the molecular constants of O 2 + , especially of those in its ground state. These are discussed and the extension of the band system in the vacuum ultra-violet region reported. The possibility of developing a simple spectrographic method for the isotopic assay of oxygen using the isotope shifts in this band system is pointed out. The revised rotational and vibrational constants in theX 2 II g ground state of O 2 + molecule are as follows :
$$\begin{gathered} \omega _e = 1903 \cdot 85 cm.^{ - 1} , \hfill \\ \omega _e x_e = 16 \cdot 18 cm.^{ - 1} , \hfill \\ B_e = 1 \cdot 6920 cm.^{ - 1} \hfill \\ and \hfill \\ r_e = 1 \cdot 1161 {\AA}. \hfill \\ \end{gathered} $$ 相似文献
997.
Decay of Gd153 has been studied by means of internal conversion and external conversion data, using Siegbahn-Slätis intermediate image beta-ray spectrometer. The existence of the 96 ± 2 Kev. transition in Gd153 has been established and its conversion coefficient has been determined. 相似文献
998.
999.
Bappanadu N. Rao 《Journal of Physics and Chemistry of Solids》1976,37(2):137-142
A two level two sublattice antiferromagnetic induced moment system is examined in the Green's function theory in the random phase approximation. Attentions are drawn to the effects of an externally applied magnetic field. It is shown that a “soft mode” behavior occurs at the transition field similar to that observed at the transition temperature in the absence of a field. The transition becomes first order in the RPA. The sublattice magnetizations and the transition field are significantly lowered compared to the molecular field theory results. 相似文献
1000.