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   117篇
  免费   0篇
电工技术   8篇
化学工业   28篇
金属工艺   1篇
机械仪表   17篇
建筑科学   4篇
能源动力   7篇
轻工业   17篇
无线电   2篇
一般工业技术   14篇
冶金工业   17篇
自动化技术   2篇
  2022年   1篇
  2021年   1篇
  2020年   1篇
  2019年   1篇
  2018年   2篇
  2017年   3篇
  2016年   1篇
  2015年   1篇
  2014年   5篇
  2013年   3篇
  2012年   3篇
  2011年   5篇
  2010年   4篇
  2009年   5篇
  2008年   2篇
  2007年   4篇
  2006年   2篇
  2005年   3篇
  2004年   1篇
  2003年   3篇
  2002年   2篇
  2001年   4篇
  2000年   2篇
  1999年   5篇
  1998年   2篇
  1997年   4篇
  1996年   5篇
  1994年   5篇
  1993年   4篇
  1992年   5篇
  1991年   6篇
  1990年   2篇
  1989年   2篇
  1987年   2篇
  1984年   1篇
  1981年   2篇
  1980年   1篇
  1977年   3篇
  1976年   4篇
  1975年   4篇
  1973年   1篇
排序方式: 共有117条查询结果,搜索用时 0 毫秒
111.
112.
113.
The effect of vitamin B12 on learning disturbance was tested in rats. Rats were fed a choline-enriched, choline-deficient, and choline-deficient diet with vitamin B12. Concentrations of acetylcholine in the brain were significantly lower in rats fed a choline-deficient diet than rats fed a choline-enriched diet. Passive avoidance learning shows that rats on a choline-deficient diet showed significantly impaired learning compared to rats on a choline-enriched diet. However, there was no significant difference of acetylcholine in the brain or in the passive avoidance learning between rats fed a choline-enriched and a choline-deficient with vitamin B12 diet. We, therefore, suggest that vitamin B12 potentiates learning in an acetylcholine-deprived brain.  相似文献   
114.
A chromatographically pure sample of red pigment from dyer's saffron (Carthamus tinctorius L) was separated into two distinct reddish components on an insoluble polyvinyl polypyrrolidone column, developed with acetone/methanol/water. These components were isolated, purified and subjected to the analytical processes. Using standard analytical techniques, only slight differences could be detected between the two types of carthamine. However, a marked difference was displayed by optical rotary dispersion spectroscopy of the two samples. This provides evidence for the existence of two geometrical isomers of carthamine.  相似文献   
115.
Summary An aqueous solution of H2O2 promoted the reddening of dyer's saffron flowers, in which carthamin accumulated. The identity of the pigment was confirmed by TLC, HPLC, and UV, and IR spectra. The chemical procedure for flower reddening is discussed in terms of its use in carthamin production.
Wasserstoffperoxyd, ein ausgezeichnetes Chromogenreagens zum Rotmachen von Safranblüten
Zusammenfassung Wäßrige Lösung von H2O2 fördert das Rotwerden von Safranblüten, in welchen Carthamin gespeichert ist. Die Identität des Farbstoffs wurde mit analytischen Methoden wie TLC, HPLC, UV- und IR-Spektren bestätigt. Die chemische Reaktion des Blütenrotwerdens wurde diskutiert zusammen mit der Nützlichkeit für die Carthamin-Farbenproduktion.

Abbreviations ODS octadecyl silan - BAW n-butanol/acetic acid/water (4+1+2, v/v) - HOAc acetic acid/water (15+85, v/v) - PAW phenol/acetic acid/water (40+1+10, v/v) - TLC thin-layer chromatography; - HPLC high performance liquid chromatography - UV ultraviolet light - VIS visible light - IR infrared light - i.d. internal diameter  相似文献   
116.
In order to examine the effect of cemented tungsten carbide dust on the animal lung, saline suspensions were intratracheally administered into the lungs of rats in a single dosage. About one-fifth of the animals died during the first three days. The acute response of the lungs was hemorrhagic edema with intense alveolar congestion. The animals killed at six months all presented pulmonary lesions of patchy fibrosis in the vicinity of the deposited dusts, occasionally associated with focal traction emphysema and bronchobronchiolar ectasia. At twelve months, two-third of the animals had neither fibrosis nor dust deposition, although the remaining animals showed pulmonary lesions similar to those seen in the six-months responders. Fibrosis of the lungs seemed to consist of collapsed alveoli with condensation of the preexistent reticulin fibers, but without noticeable collagenization. It is supposed that both the early toxic and the late fibrogenic effects of the carbide dust are attributable to the cytotoxic action of cobalt present in the dust particles. It is possible that recovery of the pulmonary lesions results from removal of the dusts from the lesions.  相似文献   
117.
Anion exchange membranes (ferricyanide ion type) prepared by the “paste method” were treated with an aqueous solution of hydrogen peroxide, and the resultant microporous membranes had no ion exchange capacity but water permeability. By measuring the water permeability of the membranes and observing the electron microphotographs of the membrane surfaces, it was elucidated that the anion exchange membranes contained microheterogeneity of colloidal dimension.  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