全文获取类型
收费全文 | 1680篇 |
免费 | 17篇 |
国内免费 | 3篇 |
专业分类
化学 | 1264篇 |
晶体学 | 21篇 |
力学 | 14篇 |
数学 | 119篇 |
物理学 | 282篇 |
出版年
2020年 | 13篇 |
2019年 | 21篇 |
2018年 | 15篇 |
2017年 | 8篇 |
2016年 | 15篇 |
2015年 | 21篇 |
2014年 | 15篇 |
2013年 | 89篇 |
2012年 | 47篇 |
2011年 | 79篇 |
2010年 | 42篇 |
2009年 | 49篇 |
2008年 | 72篇 |
2007年 | 87篇 |
2006年 | 78篇 |
2005年 | 80篇 |
2004年 | 78篇 |
2003年 | 73篇 |
2002年 | 80篇 |
2001年 | 51篇 |
2000年 | 29篇 |
1999年 | 23篇 |
1998年 | 17篇 |
1997年 | 29篇 |
1996年 | 18篇 |
1995年 | 22篇 |
1994年 | 25篇 |
1993年 | 14篇 |
1992年 | 26篇 |
1991年 | 30篇 |
1990年 | 18篇 |
1989年 | 22篇 |
1988年 | 15篇 |
1987年 | 23篇 |
1986年 | 25篇 |
1985年 | 27篇 |
1984年 | 36篇 |
1983年 | 13篇 |
1982年 | 21篇 |
1981年 | 25篇 |
1980年 | 30篇 |
1979年 | 35篇 |
1978年 | 25篇 |
1977年 | 14篇 |
1976年 | 19篇 |
1975年 | 22篇 |
1974年 | 16篇 |
1973年 | 8篇 |
1972年 | 12篇 |
1969年 | 8篇 |
排序方式: 共有1700条查询结果,搜索用时 15 毫秒
1.
The chemiluminescence (CL) intensities of various indole derivatives substituted with a glyoxylyl group at the 3-position and a hydroxyl group at the 5-position of the indole ring were compared upon the addition of H2O2 in alkaline media. The CL intensities of 3-indoleglyoxylyl chloride, 3-indoleglyoxylic acid, 5-hydroxyindole and 5-benzyloxyindole in CH3CN were 5.9-, 48-, 5.9- and 3.3-fold stronger than that of 3-methylindole. A lasting CL of 3-indoleglyoxylyl chloride was found. Under appropriate conditions, the CL emission reached a maximum within 10 min after the addition of H2O2 in the presence of NaOH, and the intensity was retained for 25 min. One of the final products via the CL reaction of 3-indoleglyoxylyl chloride was indole-3-carboxylic acid. 3-Indoleglyoxylyl chloride emitted light by decompositions via both dioxetane and dioxetanedione. An enhancement effect of beta-cyclodextrin and bovine serum albumin on the CL of 3-indoleglyoxylyl chloride was also found. 相似文献
2.
Kiyoshi Mochizuki 《Journal of Mathematical Analysis and Applications》2007,326(1):582-588
We show that the energy of solutions to the initial boundary value problem for the wave equation in exterior domains with a dissipation which is localized only near infinity tends to zero as the time goes to infinity. We do not make any geometrical condition like star-shapedness on the boundary. 相似文献
3.
Asymmetric Horner-Wadsworth-Emmons reactions of selected meso-α-dicarbonyl compounds with chiral phosphonate reagents, which possessed axially dissymmetric 1,1′-bi-2- or 8-naphthol at the carboxylate moiety as a chiral auxiliary, were examined. The reactions proceeded smoothly with good chemical yields as well as with high diastereoselectivities. Z-olefins were preferentially formed, and it was found that the free hydroxy group at the 2′- or 8′-position on the naphthalene ring plays a crucial role in the high diastereoselectivity, probably due to a complex-induced proximity effect. Mechanistic considerations are also described. 相似文献
4.
Hiroyasu Nishiguchi Hiroshi Yamada Masaru Ogura Tatsumi Ishihara Yusaku Takita 《Research on Chemical Intermediates》2003,29(7-9):755-760
The oxygen storage capacity of CeO2, Ce0.9Pr0.1O2, Pt?Rh/CeO2 and Pt?Rh/Ce0.9Pr0.1O2 was investigated by conventional GC pulse method and transient pulse techniques. It is shown that incorporation of PrOy into CeO2 matrix strongly promotes oxygen storage capacity (OSC) measured using the transient pulse technique. The improvement of OSC at low temperature is observed in Pt?Rh loaded onto CeO2 and Ce?Pr catalysts. 相似文献
5.
The present paper gives a more complete treatment of the scattering from a two-dimensional random surface than previous works. Reciprocal theorems for the stochastic wave field and the incoherent scattering distribution (bistatic cross section) are derived and the presence of backscattering enhancement in the case of a slightly random Neumann surface is demonstrated. A physical interpretation of the backscattering enhancement associated with the presence of anomalous scattering on a slightly random Neumann surface is given. Some numerical calculations are performed to show the incoherent scattering distribution and the backscattering enhancement. 相似文献
6.
7.
8.
Kiyoshi Kurosawa 《Optical Review》1997,4(1):A38-A44
This paper describes development of the optical current transducers using flint glass fiber as the Faraday effect sensing
element. Excellent polarization properties of the fiber with low birefringence are described, and the design and test data
of a current transducer using the fiber manufactured for use in electric power facilities are reviewed. Experimental results
on flexible characteristics of a scheme with round trip light transmission in the fiber is also reported. 相似文献
9.
The motion of a moored floating body under the action of wave forces, which is influenced by fluid forces, shape of the floating body and mooring forces, should be analysed as a complex coupled motion system. Especially under severe storm conditions or resonant motion of the floating body it is necessary to consider finite amplitude motions of the waves, the floating body and the mooring lines as well as non-linear interactions of these finite amplitude motions. The problem of a floating body has been studied on the basis of linear wave theory by many researchers. However, the finite amplitude motion under a correlated motion system has rarely been taken into account. This paper presents a numerical method for calculating the finite amplitude motion when a floating body is moored by non-linear mooring lines such as chains and cables under severe storm conditions. 相似文献
10.
Nuclear spin manipulation using an interface of diluted magnetic semiconductors (DMSs) is proposed. On the basis of the first-principles electronic structure calculation, we show that the hyperfine fields at an impurity site in the interface between a DMS and a base substance is dramatically changed by an external electric field. The electric field dependence of the hyperfine fields at the impurity nucleus in the interface of (InMn)As and (GaMn)As is examined. 相似文献