全文获取类型
收费全文 | 541篇 |
免费 | 30篇 |
国内免费 | 1篇 |
专业分类
化学 | 419篇 |
晶体学 | 12篇 |
力学 | 8篇 |
数学 | 38篇 |
物理学 | 95篇 |
出版年
2021年 | 3篇 |
2020年 | 5篇 |
2019年 | 2篇 |
2018年 | 12篇 |
2017年 | 6篇 |
2016年 | 8篇 |
2015年 | 14篇 |
2014年 | 11篇 |
2013年 | 34篇 |
2012年 | 19篇 |
2011年 | 30篇 |
2010年 | 19篇 |
2009年 | 14篇 |
2008年 | 50篇 |
2007年 | 29篇 |
2006年 | 33篇 |
2005年 | 27篇 |
2004年 | 25篇 |
2003年 | 21篇 |
2002年 | 21篇 |
2001年 | 7篇 |
2000年 | 5篇 |
1999年 | 3篇 |
1998年 | 5篇 |
1997年 | 3篇 |
1996年 | 7篇 |
1995年 | 5篇 |
1994年 | 3篇 |
1993年 | 6篇 |
1992年 | 7篇 |
1991年 | 2篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1988年 | 5篇 |
1987年 | 2篇 |
1986年 | 7篇 |
1985年 | 7篇 |
1984年 | 8篇 |
1983年 | 7篇 |
1982年 | 11篇 |
1981年 | 12篇 |
1980年 | 12篇 |
1979年 | 7篇 |
1978年 | 9篇 |
1977年 | 12篇 |
1976年 | 7篇 |
1975年 | 6篇 |
1974年 | 5篇 |
1973年 | 2篇 |
1962年 | 2篇 |
排序方式: 共有572条查询结果,搜索用时 328 毫秒
391.
392.
Michio Ozeki 《Journal of Number Theory》1977,9(1):112-120
Let F1(x, y),…, F2h+1(x, y) be the representatives of equivalent classes of positive definite binary quadratic forms of discriminant ?q (q is a prime such that q ≡ 3 mod 4) with integer coefficients, then the number of integer solutions of Fi(x, y) = n (i = 1,…, 2h + 1) can be calculated for each natural number n using L-functions of imaginary quadratic field ((?q)1/2). 相似文献
393.
Infrared-microwave triple resonance was applied to microwave spectroscopy of propynal, HCCCHO, in the v2 = 1 vibrational state. Eleven microwave transitions were newly observed by using a Zeeman-tuned 3.51 μm HeXe laser as the infrared radiation source. The spectrum was analyzed including the 11 transitions previously observed by double resonance. A least-squares fit of the 13 low-J transitions revealed that the rotational constants in the K?1 = 1 states were slightly different from those of the K?1 = 0 states. A higher-order rotational resonance was proposed for explanation of the effect. 相似文献
394.
Michio Kaku 《Nuclear Physics B》1975,91(1):99-108
By choosing the light-cone gauge, we remove all redundant components of the metric tensor as well as all Faddeev-Popov ghosts from the Einstein Lagrangian, from which Feynman rules for two independent transverse components can be immediately formulated. The 2 + 2 decomposition of the metric tensor proves to be simpler than the usual canonical 1 + 3 decomposition, so that all spurious components can be explicitly eliminated from the spectrum. Because the Lagrangian is now only a function of independent components, it is possible to study the unresolved problem of the functional measure for quantum gravity. We are presently studying the measure problem. 相似文献
395.
Kunihiro Osaki Mitsutoshi Fukuda Shin-Ichi Ohta Bong Shik Kim Michio Kurata 《Journal of Polymer Science.Polymer Physics》1975,13(8):1577-1589
The steady shear viscosity η(k) and the stress decay function \documentclass{article}\pagestyle{empty}\begin{document}$ \tilde \eta \left({t,k} \right)$\end{document} (the shear stress divided by the rate of shear k after cessation of steady shear flow) were measured for concentrated solutions of polystyrene in diethyl phthalate. Ranges of molecular weight M and concentration c were 7.10 × 105 to 7.62 × 106 and 0.112–0.329 g/cm3, respectively. Measurements were performed with a rheometer of the cone-and-plate type in the range 10?4 < k < 1 sec?1. The Cox–Merz relation η(k) = |η*(ω)|ω=k was tested with the experimental result (|*(ω)| is the magnitude of the complex viscosity). It was found to be applicable to solutions of relatively low M or c but not to those of high M and c. For the latter η(k) began to decrease at a lower rate of shear than |η*(ω)|ω=k did; the Cox–Merz law underestimated the effect of rate of shear. The stress decay function was assumed to have a functional form \documentclass{article}\pagestyle{empty}\begin{document}$\tilde \eta \left( {t,k} \right) = \sum {\eta _p \left( k \right)e^{ - t/\tau p\left( k \right)} } $\end{document} where τ1 > τ2 > …, and the values of τ1, τ2 η1 and η2 were determined for some solutions. The relaxation times τ1 and τ2 were found to be independent of k and equal to the relaxation times of linear viscoelasticity. At the limit of k → 0, η1 and η2 were approximately 60 and 20–30%, respectively, of η and the non-Newtonian behavior was due to large decreases of η1 and η2 with increasing k. It was shown that η1(k) may be evaluated from the relaxation strength G1(s) for the longest relaxation time of the strain-dependent relaxation modulus with a constitutive model for relatively high c–M systems as well as for low c–M systems. 相似文献
396.
397.
Michio Okuda Neville Jonathan 《Journal of Electron Spectroscopy and Related Phenomena》1974,3(1):19-25
Configuration interaction CNDO/INDO calculations have been used to interpret weak bands which have been observed in the photoelectron spectra of gaseous N2, CO and CS. These bands are due to photoionisation to states which are formally forbidden on the simple one-electron transition model. The more general implications of configuration interaction bands in polyatomic molecules are discussed, and some examples are suggested where it is believed that the effect may be important. 相似文献
398.
399.
400.
Tanaka YO Shigemitsu S Nagata M Shindo M Okamoto Y Yoshikawa H Itai Y 《Magnetic resonance imaging》2002,20(3):301-304
Decidual changes of the ectopic endometrial stroma during pregnancy are well known among pathologists and obstetricians. However, they appear very similar to endometrial cysts with malignant transformation when imaged. Balanced fast field echo (BFFE) is a steady-state free precession imaging sequence and its contrast is decided by the T1/T2 ratio. The authors report a case of a decidualized endometrial cyst in which mural nodules were isointense with the nomotopic decidualized endometrium on T1- and T2-weighted images and BFFE. Isointensity with the nomotopic endometrium is an MR characteristic that can differentiate a decidualized endometrial cyst from malignant transformation. BFFE is a good alternative sequence during pregnancy because of its shorter acquisition time and lower radiofrequency absorption. 相似文献