全文获取类型
收费全文 | 404篇 |
免费 | 6篇 |
国内免费 | 1篇 |
专业分类
化学 | 318篇 |
晶体学 | 6篇 |
力学 | 4篇 |
数学 | 7篇 |
物理学 | 76篇 |
出版年
2022年 | 2篇 |
2021年 | 4篇 |
2019年 | 6篇 |
2018年 | 3篇 |
2016年 | 4篇 |
2015年 | 6篇 |
2014年 | 6篇 |
2013年 | 29篇 |
2012年 | 15篇 |
2011年 | 22篇 |
2010年 | 11篇 |
2009年 | 8篇 |
2008年 | 23篇 |
2007年 | 10篇 |
2006年 | 21篇 |
2005年 | 25篇 |
2004年 | 9篇 |
2003年 | 7篇 |
2002年 | 14篇 |
2001年 | 3篇 |
2000年 | 3篇 |
1999年 | 3篇 |
1997年 | 4篇 |
1996年 | 3篇 |
1995年 | 2篇 |
1994年 | 2篇 |
1993年 | 3篇 |
1992年 | 2篇 |
1991年 | 4篇 |
1990年 | 3篇 |
1989年 | 2篇 |
1988年 | 3篇 |
1986年 | 2篇 |
1985年 | 9篇 |
1984年 | 16篇 |
1983年 | 5篇 |
1982年 | 12篇 |
1981年 | 20篇 |
1980年 | 21篇 |
1979年 | 15篇 |
1978年 | 12篇 |
1977年 | 6篇 |
1976年 | 6篇 |
1975年 | 4篇 |
1974年 | 7篇 |
1973年 | 2篇 |
1972年 | 2篇 |
1968年 | 3篇 |
1965年 | 1篇 |
1959年 | 1篇 |
排序方式: 共有411条查询结果,搜索用时 15 毫秒
1.
2.
3.
Infrared and Raman spectra of 1,2-dibromoethane CH2BrCH2Br and CD2BrCD2Br were observed in the liquid state, and the fundamental frequencies were determined by comparison with those of related molecules. Infrared absorption intensities of fundament bands were measured in the liquid state, and the intensity data were interpreted on the basis of the valence-optical theory. From the converged value of a population ratio, the energy difference between the trans and gauche isomers was determined, which was in good agreement with the value obtained from the temperature effect of the IR spectrum. 相似文献
4.
Treatment of alkyl allyl carbonates derived from various alcohols with a palladium catalyst in MeCN affords ketones and aldehydes in high yields. This new method of oxidation of alcohols can be applied to various alcohols except simple primary alcohols. 相似文献
5.
Isotropie Raman spectra of the symmetric C—H stretching bands of several organic molecules are measured in the neat liquid and in solvents including water. The linewidths are interpreted on the basis of the vibrational dephasing model, and intermolecular interactions between the solutes and solvents are discussed. 相似文献
6.
The conductance of potassium iodide has been measured in the solvents ethylene carbonate, water, methyl ethyl ketone, and pairwise mixtures of these solvents at 40°C; and ethylene carbonate-water, tetramethylene sulfone-water, dimethyl sulfoxide-water, tetrahydrofuran-water, ethylene carbonate-tetramethylene sulfone-water, ethylene carbonate-tetramethylene sulfone, and tetrahydrofuran-dimethyl sulfoxide at 25°C. For dielectric constants greater than about 60, the pairing constants KA are in the range 0.3–2.0; no correlation between KA and solvent properties could be established. For lower dielectric constants, KA increases exponentially with decreasing dielectric constant. Addition of a proton, acceptor to water initially decreases KA regardless of whether the dielectric constant of the mixture is higher or lower than that of water, suggesting that ion pairs in water may be stabilized by cage structures. The Walden product Ao is also decreased by the addition of proton acceptors. 相似文献
7.
Allylation of carbonucleophiles with allylic carbamates under neutral conditions has been studied. The C-allylation of carbonucleophile is competitive with the N-allylation of amines, and the structure of amines is crucial for the selectivity. Bulky secondary amines gave the best results. Also a new method of protection-deprotection of amines as carbamates has been developed. Smooth deprotection is possible by the palladium-catalyzed reaction of allyl carbamates with formic acid. This method is particulary useful for primary amines, including optically active amino acids. 相似文献
8.
Raman spectra of glassy aqueous LiX and CaX2 solutions (X = Cl,Br and I) in the low frequency region
Raman spectra of glassy aqueous LiX and CaX2 solutions are obtained in the low frequency region (10–900 cm?1). Two low frequency Raman bands are clearly observed. A qualitative discussion is given for the intensity correlation and observed frequency shifts of these bands with halide ions. 相似文献
9.
Dehydrroxy-trans-resorcylide () was synthesized by efficient intramolecular alkylation of the protected cyanohydrin. The butadiene telomer obtained by the palladium catalyzed reaction of butadiene with acetic acid was used as a suitable block of the carbocycle. 相似文献
10.
Hiroki Nakamura Jiro Tanaka Nobuaki Nakashima Keitaro Yoshihara 《Chemical physics letters》1981,77(2):419-421
The photoionization of 8-anilino-1-naphthalenesulfonate in polar solvents occurs through a biphotonic process, as proved by nanosecond flash photolysis. A transient absorption of a charge transfer to solvent (CTTS) state is found with ≈10 ns life-time. The state is shown to be an intermediate of the photoionization process. 相似文献