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   112篇
  免费   5篇
化学   59篇
晶体学   1篇
数学   3篇
物理学   54篇
  2022年   2篇
  2020年   2篇
  2018年   1篇
  2017年   3篇
  2016年   6篇
  2015年   1篇
  2014年   2篇
  2013年   4篇
  2012年   4篇
  2011年   2篇
  2010年   3篇
  2009年   3篇
  2008年   3篇
  2007年   1篇
  2006年   4篇
  2005年   4篇
  2004年   5篇
  2003年   3篇
  2002年   2篇
  2001年   1篇
  2000年   2篇
  1999年   1篇
  1998年   2篇
  1997年   1篇
  1996年   3篇
  1995年   7篇
  1994年   4篇
  1993年   5篇
  1992年   4篇
  1991年   2篇
  1990年   2篇
  1989年   2篇
  1988年   3篇
  1987年   2篇
  1986年   2篇
  1984年   1篇
  1983年   2篇
  1982年   1篇
  1981年   1篇
  1977年   1篇
  1976年   1篇
  1972年   1篇
  1964年   1篇
  1963年   1篇
  1961年   1篇
  1959年   1篇
  1934年   1篇
  1923年   1篇
  1916年   1篇
  1907年   2篇
排序方式: 共有117条查询结果,搜索用时 15 毫秒
11.
12.
Oleic acid substituted by iodine and saponified by Ca2+ cations has been studied by129I Mössbauer spectroscopy. The quadrupole coupling constants and isomer shifts, determined from the γ-resonance spectra recorded at 4.2 K, have been described by 5p and 5s orbital populations of iodine. It was also found that saponification of the fatty acid has no significant influence on the measured iodine bonds. However, the increased order of fatty acids in soap form is reflected by narrowing of the resonant linewidth due to the reduction of the electric field gradient distribution.  相似文献   
13.

Background  

Growth hormone (GH) plays an incompletely understood role in the development of the central nervous system (CNS). In this study, we use transgenic mice expressing a growth hormone antagonist (GHA) to explore the role of GH in regulating postnatal brain, spinal cord and body growth into adulthood. The GHA transgene encodes a protein that inhibits the binding of GH to its receptor, specifically antagonizing the trophic effects of endogenous GH.  相似文献   
14.
The ZEUS detector has been used to measure the proton structure functionF 2. During 1993 HERA collided 26.7 GeV electrons on 820 GeV protons. The data sample corresponds to an integrated luminosity of 0.54 pb–1, representing a twenty fold increase in statistics compared to that of 1992. Results are presented for 7Q 2<>4 GeV2 andx values as low as 3×10–4. The rapid rise inF 2 asx decreases observed previously is now studied in greater detail and persists forQ 2 values up to 500 GeV2.supported by Worldlab, Lausanne, Switzerland  相似文献   
15.
16.
The synthesis of ethyl-3,4,6-tri-O-benzyl-D -glucopyranoside and of ethyl-3,4,6-tri-O-benzyl-D -galactopyranoside is described. These compounds are isomers of ethyl-3,5,6-tri-O-benzyl-D -glucofuranoside, GLYVENOL ®, a substance displaying interesting pharmacological actions.  相似文献   
17.
18.
19.
A review of research and development of Lu3Al5O12 (LuAG)-based single crystal scintillators is presented. Crystals of this type have been prepared by the micro-pulling down method at the initial stage of material screening and by Czochralski or Bridgman methods to obtain higher quality and larger size single crystals afterward. Several different activators, namely Ce3+, Pr3+, Yb3+ and Sc3+ have been reported in the literature and such doped LuAG single crystals have been extensively studied to understand a number of issues, including: the scintillation mechanism, underlying energy transfer and trapping processes including the nature and role of material defects involved in the scintillation process and their relation to manufacturing technology. Significant improvements in the understanding of aluminum garnet scintillators lead to the discovery of multicomponent garnet single crystal scintillators in 2011, which are described. These materials gave rise to new class of ultraefficient complex oxide scintillators, the light yield of which considerably exceeds the values achieved for the best Ce-doped orthosilicate scintillators.  相似文献   
20.

It is well known that clothes used in sporting activity are a barrier for heat exchange between the environment and athlete, which should help in thermoregulation improvement. However, it is difficult to evaluate which top is best for each athlete according to the characteristics of the sport. Researchers have tried to measure the athlete’s temperature distribution during exercise at the base layers of tops with different approaches. The aim of this case study was to investigate the use of thermography for thermo-active base layer evaluation. Six new base layers were measured on one cyclist volunteer during a progressive training on a cycloergometer. As a control condition, the skin temperature of the same volunteer was registered without any layer with the same training. A training protocol was selected approximate to cycling race, which started from the warm-up stage, next the progressive effort until the race finished and at the end “cool-down” stage was over. In order to show which layer provided the strongest and weakest barrier for heat exchange in comparison with environment, the temperature parameters were taken into consideration. The most important parameter in the studies was the temperature difference between the body and the layers, which was changing during the test time. The studies showed a correlation between the ergometer power parameter and the body temperature changes, which has a strong and significant value. Moreover, the mass of every layer was checked before and after the training to evaluate the mass of the sweat exuded during the test. From this data, the layer mass difference parameter was calculated and taken into consideration as a parameter, which may correspond with the mean heart rate value from each training. A high and positive correlation coefficient was obtained between the average heart rate and the mass difference for the base layers. Thermal analysis seems to have a new potential application in the objective assessment of sports clothing and may help in choosing the proper clothes, which could support heat transfer during exercising and protect the body from overheating.

  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