首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   124篇
  免费   4篇
化学   49篇
力学   8篇
数学   5篇
物理学   66篇
  2022年   1篇
  2020年   1篇
  2019年   1篇
  2018年   1篇
  2016年   3篇
  2015年   1篇
  2014年   3篇
  2013年   10篇
  2012年   4篇
  2011年   9篇
  2010年   5篇
  2009年   8篇
  2008年   4篇
  2007年   5篇
  2006年   5篇
  2005年   5篇
  2004年   5篇
  2003年   9篇
  2002年   6篇
  2001年   1篇
  2000年   7篇
  1998年   1篇
  1997年   1篇
  1996年   3篇
  1995年   1篇
  1994年   3篇
  1993年   5篇
  1992年   1篇
  1991年   1篇
  1990年   1篇
  1989年   1篇
  1988年   1篇
  1986年   2篇
  1985年   1篇
  1983年   1篇
  1981年   3篇
  1980年   1篇
  1979年   2篇
  1978年   3篇
  1976年   1篇
  1973年   1篇
排序方式: 共有128条查询结果,搜索用时 31 毫秒
121.
We study the symmetric texture of geometric form with 2-zeros to see if it is consistent with the presently-known neutrino masses and mixings. In the neutrino mass matrix elements we obtain numerically the allowed region of the parameters including CP-violating phases, which can reproduce the present neutrino experiment data. The result of this analysis dictates the narrow region for the GUT model including Pati–Salam symmetry with texture zeros to be consistent with the experimental data. The |Ue3| and JCP are also predicted in such models.  相似文献   
122.
123.
Heterosubspecific mating experiments were carried out between two subspecies of cabbage butterflies, British Pieris rapae rapae and Japanese P. rapae crucivora, to examine how accurately males recognize the mates. The two subspecies are different in that the wings of female P. rapae rapae reflect little UV light, whereas those of female P. rapae crucivora are strongly UV-reflective. The wing colouration of P. rapae crucivora involving UV is believed to be critical in mate recognition. The results showed that males of both subspecies displayed mating behaviours, to and copulated with, females of both subspecies. Furthermore, P. rapae crucivora males exhibited mating behaviours and attempted to copulate with females of Pieris melete with low UV reflectance which are critically different from P. rapae crucivora females with high UV reflectance. Based on these findings, we propose the “pioneer male” hypothesis, which argues that such inaccurate mate recognition may sometimes be selectively beneficial for males and thus an adaptive mating strategy. The “pioneer male” was discussed in terms of its possible role in the evolution.  相似文献   
124.
Artificially stacked structures of [(infinite layer CaCuO2)k/(superconducting (Cu, C)Ba2CuOx:(Cu, C)-1201)l]m were fabricated on SrCuO2 buffer layer by means of sequential deposition of each block using pulsed laser deposition. Smooth and epitaxial growth all over the deposition cycles of (Cu, C)-1201 and CaCuO2 were confirmed by streak patterns of in situ RHEED. In comparison with (Cu, C)-1201 single layer films, the artificial stacking resulted in a rise of superconducting properties, Tc-onset and Tc(ρ=0) up to 95 K and 65 K, respectively.  相似文献   
125.
In vivo temporal EPR imaging was conducted on the brain of rats that received one of two kinds of blood-brain barrier-permeable nitroxide radicals via the tail vein-one is a water-soluble 3-hydroxymethyl-2,2,5,5-tetramethylpyrrolidine-1-oxyl (hydroxymethyl-PROXYL); and the other is a non-water-soluble 3-methoxycarbonyl-2,2,5,5-tetramethylpyrrolidine-1-oxyl (PCAM). From temporal EPR imaging data, temporal changes in the distribution of the nitroxide radical in the cerebral cortex, striatum, and hippocampus in the brain were investigated. It was found that the half-lives of the three parts in the brain of hydroxymethyl-PROXYL are longer and their EPR signal intensities are greater than those of PCAM.  相似文献   
126.
We evaluated the diagnosis of thrombus and the effect of antithrombic therapy by using 67Ga-DFO-DAS-Fibrinogen (67Ga-Fbg.) scintigraphy in vivo. The 11 patients with chronic renal failure had the operation of the internal A-V shunt. The two groups were divided the group I (the patients were injected 67Ga-Fbg. within 5 days after the operation of A-V shunt) from the group II (the patients were injected 67Ga-Fbg. from 7 months to 6 years after A-V shunt). We examined 72 h after the injection of 67Ga-Fbg. in all patients. In group I, the scintigraphy showed the deposition of 67Ga-Fbg. in all 5 patients, but 3 patients were given dipyridamole (75-300 mg). The scintigraphy examined 3 weeks after A-V shunt were negative in 2 patients in group I. In group II, the scintigraphy showed the deposition of 67Ga-Fbg. in the two of 6 patients. Within 5 day after A-V shunt, we observed there was the tendency of the thrombus formation. The scintigraphy of 67Ga-Fbg. was useful for the detection of thrombus in vivo.  相似文献   
127.
Plasmid DNA has been successfully delivered to mammalian cells by applying a nanosecond pulsed laser-induced stress wave (LISW). Cells exposed to a LISW were selectively transfected with plasmids coding for green fluorescent protein. It was also shown that transient, mild cellular heating (approximately 43 degrees C) was effective in improving the transfection efficiency.  相似文献   
128.
A Brewster-cut CsLiB6O10 crystal is employed as an external resonant frequency doubler to generate cw deep-UV radiation at 266 nm. We have generated 5.0 W of usable cw output power, which is 6.1 W in the crystal, for an incident green power of 9.6 W, corresponding to an internal conversion efficiency of 61.8%. The power obtained is, to our knowledge, three times higher than previously reported for cw 266-nm generation.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号