全文获取类型
收费全文 | 219篇 |
免费 | 1篇 |
国内免费 | 1篇 |
专业分类
化学 | 146篇 |
晶体学 | 1篇 |
力学 | 1篇 |
数学 | 23篇 |
物理学 | 50篇 |
出版年
2020年 | 2篇 |
2019年 | 2篇 |
2018年 | 2篇 |
2017年 | 1篇 |
2016年 | 1篇 |
2015年 | 4篇 |
2014年 | 4篇 |
2013年 | 8篇 |
2012年 | 8篇 |
2011年 | 6篇 |
2010年 | 3篇 |
2009年 | 5篇 |
2008年 | 14篇 |
2007年 | 6篇 |
2006年 | 9篇 |
2005年 | 10篇 |
2004年 | 7篇 |
2003年 | 11篇 |
2002年 | 14篇 |
2001年 | 4篇 |
2000年 | 15篇 |
1999年 | 3篇 |
1998年 | 3篇 |
1997年 | 4篇 |
1996年 | 2篇 |
1993年 | 1篇 |
1992年 | 10篇 |
1991年 | 3篇 |
1990年 | 5篇 |
1989年 | 2篇 |
1988年 | 4篇 |
1987年 | 5篇 |
1986年 | 2篇 |
1985年 | 8篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1975年 | 4篇 |
1974年 | 4篇 |
1973年 | 2篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1938年 | 1篇 |
1932年 | 2篇 |
排序方式: 共有221条查询结果,搜索用时 15 毫秒
51.
Koji Seto Hiroshi Shimojitosyo Hideyuki Imazaki Hiroshi Matsubara Shigetoshi Takahashi 《Liquid crystals》2013,40(4):517-518
Abstract Chiral 1, 2-diphenylethane derivatives have been synthesized and found to form stable chiral Sc phases exhibiting ferroelectric properties. Comparison with diphenylacetylene derivatives revealed that flexibility of the bridging groups between two benzene nuclei strongly influences the stability of mesophases as well as transition temperatures. 相似文献
52.
Asymmetric epoxidation of trans-cinnam-aldehyde and chalcone by the use of H2sp>O2sp> as an oxidizing agent in alkaline media in the presence of cyclodextrins gave the corresponding epoxides with enantiomeric excess up to 8 %. 相似文献
53.
Gerard van der Geer Toshiyuki Katsura 《Rendiconti del Circolo Matematico di Palermo》1938,62(1):111-125
We discuss relations between certain invariants of varieties in positive characteristic, like the \(a\)-number and the height of the Artin-Mazur formal group. We calculate the \(a\)-number for Fermat surfaces. 相似文献
54.
55.
The dioxopiperazine metabolites of quinapril in plasma and urine were extracted with hexane-dichloroethane (1:1) under acidic conditions. Following derivatization with pentafluorobenzyl bromide and purification of the desired reaction products using a column packed with silica gel, the metabolites were analysed separately by capillary column gas chromatography-electron-impact mass spectrometry with selected-ion monitoring. The limits of quantitation for the metabolites were 0.2 ng/ml in plasma and 1 ng/ml in urine. The limits of detection were 0.1 ng/ml in plasma and 0.5 ng/ml in urine, at a single-to-noise ratio of greater than 3 and greater than 5, respectively. The proposed method is applicable to pharmacokinetic studies. 相似文献
56.
Based on real-time observation and micromanipulation, analytical methods for single DNA molecules have been under development for some time. Precise manipulation, however, is still difficult because single molecules are too small for conventional techniques. We have developed a chemical reaction system that uses water droplets in oil as containers of materials. The water droplets can be manipulated by optical force. The manipulation of the water droplets permits the fusion of two selected droplets. This process corresponds to mixing of different samples. We designate this system as "w/o (water-in-oil emulsion) microreactor system", and each droplet can be thought of as a "microreactor". In this system, single molecules can be manipulated readily, as a molecule can be contained in a microm-sized microreactor. The microreactor utilizes extremely small quantities of samples, therefore, reactions are rapid, as diffusion times in the microreactor are very short. The manipulation technique of the microreactors based on optical force has been applied to induce fusion between microreactors loaded with DNA and YOYO, a fluorescent dye that binds to DNA. This fusion induced a rapid binding of YOYO. 相似文献
57.
Isao Kadota Naoko NishinaHiroki Nishii Shigetoshi KikuchiYoshinori Yamamoto 《Tetrahedron letters》2003,44(43):7929-7932
A convergent synthesis of the F-K ring segment of brevetoxin B has been achieved via the intramolecular allylation of an α-chloroacetoxy ether and subsequent ring-closing metathesis. 相似文献
58.
Magnetic susceptibility and torque measurements of FeV2S4, FeV2Se4 and FeTi2Se4 were made using the powder and the single crystal samples. The inverse susceptibility of FeV2S4, FeV2Se4 and FeTi2Se4 changed its slope at 850, 820 and 700 K, respectively, at which temperature the order-disorder transition of cation vacancies should seem to take place. Above these temperatures the paramagnetic moment obtained for these compounds was in the range of 5.26–5.37 μB, close to that of the high spin state Fe2+. Below these temperatures the paramagnetic moment was reduced to 4.23–4.35 μB.The antiferromagnetic spin axis of FeV2S4 was in the neighborhood of the [101] direction and that of FeV2Se4 and FeTi2Se4 in the direction of the c-axis. The large magnetic anisotropy observed and the preference of the magnetic moments for the direction of the c-axis were attributed to the spin-orbit interaction of Fe2+ electrons in the trigonal crystal field. 相似文献
59.
60.
A. Tani C. Yamanaka M. Ikeya O. Ohtaka M. Takada T. Katsura 《Radiation measurements》2000,32(5-6):473-477
Optically stimulated luminescence (OSL) of synthetic stishovite was investigated for a future dating technique of meteor impact craters. Luminescence around 330 nm was measured on the γ-ray irradiated stishovite under two stimulating light sources of infrared laser (830 nm) and blue light emitting diode set (470 nm). Thermoluminescence (TL) studies before and after the OSL measurements showed the intensities around 100–200°C and 220–350°C to increase and those around 350–450°C to decrease. This indicates that a part of deep-trapped charges excited during the OSL measurements were retrapped by shallower traps. The infrared stimulated luminescence (IRSL) after the TL measurement up to 450°C could not be detected, while the blue light stimulated luminescence (BLSL) after TL had about one-tenth of the intensity before TL. This indicates that a part of the charges in shallower traps were detrapped thermally and returned to the deeper traps which were related to BLSL. The result implies that some of the BLSL-related traps are quite stable at room temperature and could be used for geological dating. In addition, two paramagnetic centers produced by sudden release of high pressure in synthesis process were found in the unirradiated stishovite by electron spin resonance (ESR). Their g-factors are g=2.00181 and g=2.00062 for an axial signal and g=2.00305 for the other isotropic signal. These signals could be used for an evidence of impacts if those signals could be stored in geological time. 相似文献