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   220篇
  免费   10篇
  国内免费   1篇
化学   159篇
晶体学   14篇
力学   6篇
数学   18篇
物理学   34篇
  2023年   1篇
  2022年   1篇
  2021年   1篇
  2020年   2篇
  2019年   1篇
  2016年   5篇
  2015年   1篇
  2014年   10篇
  2013年   15篇
  2012年   10篇
  2011年   14篇
  2010年   9篇
  2009年   14篇
  2008年   11篇
  2007年   10篇
  2006年   13篇
  2005年   8篇
  2004年   10篇
  2003年   6篇
  2002年   16篇
  2001年   2篇
  2000年   8篇
  1999年   2篇
  1998年   5篇
  1997年   3篇
  1996年   2篇
  1995年   1篇
  1993年   4篇
  1992年   7篇
  1990年   3篇
  1989年   1篇
  1988年   3篇
  1987年   2篇
  1985年   5篇
  1984年   4篇
  1983年   1篇
  1982年   1篇
  1980年   2篇
  1978年   2篇
  1977年   2篇
  1974年   1篇
  1969年   1篇
  1966年   1篇
  1934年   1篇
  1925年   1篇
  1923年   2篇
  1920年   2篇
  1908年   2篇
  1907年   1篇
  1893年   1篇
排序方式: 共有231条查询结果,搜索用时 0 毫秒
31.
Ohne ZusammenfassungEigenbericht über einen auf der Naturforscherversammlung in Dresden gehaltenen Vortrag.  相似文献   
32.
33.
We have developed 680-nm-band AlGalnP visible laser diodes having very lowintensity noise with stable self-sustained pulsation. The pulsation characteristics were affected by current spreading outside the ridge stripe. We obtained AlGalnP visible laser diodes with stable self-sustained pulsation by optimizing the ridge structure. The lasers achieved relative intensity noise (RIN) as low as-136 dB Hz–1 in the temperature range 20–50°C at 3 mW.  相似文献   
34.
35.
1,1,2,2-Tetramethyl-1,2-disilacyclopentane undergoes the SiSi/SiSi metathesis reaction with vinyl- or ethynyl-substituted disilanes in the presence of a palladium complex.  相似文献   
36.
When the design work was commenced on the YS-11 transport airplane in 1959, the fatigue behavior of the structure was one of the most cardinal problems in the structural design, then the various design principles were introduced in order to overcome the fatigue problems, and the fatigue test of the full-scale airplane structure was planned to guarantee a fatigue life of 30,000 flight hours. In order to perform the fatigue test of the full-scale air-plane structure, the equipment for the wing fatigue test and for the fuselage fatigue test was developed separately. The former consisted of sixteen hydraulic actuators, controlled automatically, and a program device, being able to program the four different repeated loads; the latter was a familiar water tank in which the fuselage was pressurized by water and loaded, the external loads corresponding to gust loads, standing on the ground loads and the others by actuators. Concerning these tests, the following problems will be explained in our report:
  1. 1.
    The structure and operation of the equipment of the full-scale fatigue test.  相似文献   
37.
The effects of ionene polymers (6,3-ionene, 6,6-ionene, 6,8-ionene, and 6,12-ionene) with various charge densities upon association constants K for the complexation between flavin mononucleotide and indoleacetate have been studied. Except for 6,12-ionene, K increases with increasing polymer concentration then passes through a maximum, and declines at high polymer concentrations. The value of the maximum K increases in the order 6,8-ionene > 6,3-ionene > 6,6-ionene. In contrast, 6,12-ionene gives only a monotone increasing curve with increasing polymer concentration. These curves are analyzed using the theory of the partition coefficient proposed in the previous paper. The types of the curves that the theory predicts are classified in greater detail than in the previous paper, and examples are given. © 1993 John Wiley & Sons, Inc.  相似文献   
38.
When a stress wave generated by focusing a femtosecond laser is loaded on an animal cell adhered on a substrate, the cell is detached from the substrate. There are two possible mechanisms for the cell detachment: (a) The cell is detached from a scaffold coated on a glass plate, and (b) the cell is detached from the glass plate with the scaffold. In this work, we have studied the cell-detachment mechanism by visualizing the scaffold with a fluorescence probe of quantum dots. When the cell was detached from the substrate, fluorescence from the scaffold simultaneously disappeared from the glass plate, although the scaffold was not irradiated by the laser. This indicates that detachment due to the stress wave is attributed to mechanism (a). On the other hand, when the cell was detached from the substrate by a trypsin treatment, the fluorescence from the scaffold remained, suggesting mechanism (b). By comparing both results, it is considered that physiological damage of the cell membrane during the detachment process by femtosecond laser-induced stress wave is less than that due to the trypsin treatment.  相似文献   
39.
The electron impact induced fragmentation of 1-benzoylbenzotriazole has been studied by 13C labelling experiments. It has been found that the loss of CO from the [M ? N2]+˙ ions proceeds by two routes; about 78% of the ions decompose via the molecular ions of the corresponding thermal fragmentation product, 2-phenylbenzoxazole, and 22% via those of the corresponding photochemical fragmentation product, 6-phenanthridone.  相似文献   
40.
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