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   152篇
  免费   3篇
电工技术   2篇
化学工业   37篇
金属工艺   4篇
机械仪表   23篇
建筑科学   8篇
能源动力   4篇
轻工业   3篇
水利工程   3篇
石油天然气   2篇
无线电   8篇
一般工业技术   12篇
冶金工业   42篇
原子能技术   1篇
自动化技术   6篇
  2020年   1篇
  2019年   5篇
  2017年   2篇
  2016年   2篇
  2014年   3篇
  2013年   8篇
  2012年   2篇
  2011年   5篇
  2010年   3篇
  2009年   7篇
  2008年   6篇
  2007年   4篇
  2006年   1篇
  2005年   1篇
  2004年   2篇
  2003年   2篇
  2002年   2篇
  2001年   4篇
  2000年   3篇
  1999年   3篇
  1998年   16篇
  1997年   4篇
  1996年   6篇
  1995年   4篇
  1994年   3篇
  1993年   5篇
  1992年   2篇
  1991年   2篇
  1990年   3篇
  1989年   2篇
  1988年   3篇
  1987年   1篇
  1986年   2篇
  1985年   1篇
  1984年   3篇
  1983年   1篇
  1982年   3篇
  1981年   5篇
  1980年   3篇
  1979年   1篇
  1978年   1篇
  1977年   4篇
  1976年   2篇
  1974年   1篇
  1973年   3篇
  1970年   1篇
  1964年   2篇
  1963年   2篇
  1962年   1篇
  1948年   1篇
排序方式: 共有155条查询结果,搜索用时 15 毫秒
1.
BACKGROUND: Questionnaire-based surveys from several countries have consistently detected adverse health associated with home dampness and mould growth. METHODS: To test the validity of questions commonly used to indicate the presence of indoor mould, questionnaires were administered in 403 homes where dust samples were taken for viable fungi and air samples for ergosterol. RESULTS: Geometric mean concentrations of the total viable fungi were 255 (SE 116) x 10(3) CFU/g when mouldy odours were reported and 155 (SE 55) when odours were not reported (P = 0.01). Similarly, reported water damage was associated with a 50% increase (P = 0.06). Geometric mean concentrations of the predominantly indoor-source fungi, Aspergillus plus Penicillium, were twice as high when mould or mildew was reported than when not mentioned (P = 0.01). The presence of reported mould or water damage was unrelated to the presence of detectable levels of ergosterol. There was evidence for reporting bias: in the presence of low concentrations of viable fungi in dust, respondents reporting allergies were more likely to report visible mould growth (odds ratio [OR] = 1.8, 95% confidence interval [CI]: 0.9-3.5, P = 0.10. In the presence of elevated concentrations of dust fungi, respondents who smoked were less likely to report visible mould growth, (OR = 0.4, 95% CI: 0.2-0.7, P = 0.005). CONCLUSIONS: Reported mould, water damage, and mouldy odours were associated with elevated levels of indoor fungi. However, inaccuracy was high and there was evidence of a systematic reporting bias. Future research should concentrate on developing accurate objective measures of exposure to fungi, and then use this information to develop valid questionnaires. Currently, objective measures not questionnaires, are recommended to clarify the health effects of indoor fungi.  相似文献   
2.
Aspects of the analysis of an elderly patient with early disintegrative experiences are described: separation anxiety, an internalized attack upon vitality, and the fear of dependency were prominent features of the transference/countertransference relationship, while the search for meaning as death drew nearer continued to be the central theme. The patient's many dreams reveal a wealth of images whose complex interlinkings provided evidence of a heightened and energized individuation process aiming at the integrity of personality.  相似文献   
3.
Sinkler W  Own CS  Marks LD 《Ultramicroscopy》2007,107(6-7):543-550
A 2-beam model is used to simulate precession electron diffraction (PED) intensities. It is shown that this model can be inverted with minimal knowledge of the underlying crystal structure, permitting structure factor amplitudes to be deduced directly from measured intensities within the 2-beam approximation. This approach may be used in conjunction with direct methods to obtain correct, kinematically interpretable structure indications for data sets from relatively thin crystals (less than approximately 400A), and an experimental example based on (Ga,In)(2)SnO(5) is presented. The failure of this approach at large thickness is illustrated by an additional data set for MFI zeolite. The 2-beam approximation provides a simple model for PED intensities, and inversion using this model shows advantages over a kinematical approximation. It is however too rough approximation to be of general use and ultimately it is to be hoped that more accurate models with similar ease of use can be derived to treat PED data.  相似文献   
4.
5.
6.

Abstract  

Aberration-corrected scanning transmission electron microscopy at the sub-?ngstr?m resolution allows imaging the structure of catalytic materials at the single atom level and permits fundamental studies of the behavior of heavy metal catalytic species as a result of elevated temperature gas-treatments. The present study is aimed at understanding the development of clusters and nanoparticles of Pt on γ-alumina during reduction treatments of a pre-oxidized highly dispersed catalyst. A special built ex situ reactor and a specimen holder allowing cyclic anaerobic transfer between the reactor and microscope were used for the study. The number of atoms in a nascent cluster can be determined along with the general shape of the cluster. Reduction experiments without air exposure of the sample showed that although clusters are formed at 500 °C, many Pt atoms are not associated with the cluster and are still dispersed on the catalyst support. After a 700 °C reduction, all of the Pt atoms are associated with the clusters. Movement of the clusters on the catalyst support is different depending upon the catalyst support.  相似文献   
7.
8.
Template synthesis of gold nanotubes in an anodic alumina membrane   总被引:1,自引:0,他引:1  
Nanotube-containing membranes prepared by the template method show promise for use as highly selective filters for membrane-based chemical and biological separations. Most of the work to date has been done on gold nanotubes prepared by electroless deposition of Au within the pores of polymeric filtration membranes. These polymeric filters have very low porosities (< 1%), and, as a result, the flux through Au nanotube membranes based on these templates is very low. In contrast, the other popular template membranes-anodic aluminas-have high porosities-30% to 50%. In spite of this potential advantage of anodic alumina templates, there have been no reports of electrolessly plated Au nanotubes within the pores of these templates. This is because the electroless plating method used to deposit Au nanotubes in polymeric templates does not work in aluminas. We have developed a modified electroless plating strategy that can be used to deposit high-quality Au nanotubes within the pores of the alumina templates. We describe this new plating method here.  相似文献   
9.
The Critical Oxygen Index test is widely used as a measure of the flammability of many substances. This paper reviews attempts that have been made to compare Oxygen Index values with the results from other fire tests. Varying degrees of correlation are apparent, depending on the properties being measured in the respective tests.  相似文献   
10.
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