全文获取类型
收费全文 | 226篇 |
免费 | 20篇 |
专业分类
电工技术 | 1篇 |
化学工业 | 56篇 |
金属工艺 | 8篇 |
机械仪表 | 2篇 |
建筑科学 | 19篇 |
矿业工程 | 1篇 |
能源动力 | 15篇 |
轻工业 | 25篇 |
无线电 | 12篇 |
一般工业技术 | 60篇 |
冶金工业 | 27篇 |
自动化技术 | 20篇 |
出版年
2023年 | 2篇 |
2021年 | 8篇 |
2020年 | 5篇 |
2019年 | 15篇 |
2018年 | 5篇 |
2017年 | 9篇 |
2016年 | 7篇 |
2015年 | 11篇 |
2014年 | 13篇 |
2013年 | 8篇 |
2012年 | 21篇 |
2011年 | 15篇 |
2010年 | 4篇 |
2009年 | 5篇 |
2008年 | 2篇 |
2007年 | 11篇 |
2006年 | 8篇 |
2005年 | 6篇 |
2004年 | 3篇 |
2003年 | 11篇 |
2002年 | 6篇 |
2001年 | 6篇 |
2000年 | 3篇 |
1999年 | 7篇 |
1998年 | 6篇 |
1997年 | 3篇 |
1996年 | 8篇 |
1995年 | 3篇 |
1994年 | 5篇 |
1993年 | 2篇 |
1992年 | 3篇 |
1991年 | 10篇 |
1990年 | 5篇 |
1989年 | 3篇 |
1987年 | 1篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1981年 | 1篇 |
1979年 | 1篇 |
1977年 | 1篇 |
排序方式: 共有246条查询结果,搜索用时 15 毫秒
1.
It was found, that To?pa Peat Preparation (TPP) administered to healthy volunteers in doses of 100-300 mg/day during 14 days evoked the stimulation of the phagocytic and bactericidal activity of the granulocytes. The dose of 600 mg/day causes only a transient and insignificant increase of phagocytic and bactericidal properties of the granulocytes. 相似文献
2.
3.
The shear bond strengths of the XR-Bonding System used in conjunction with Herculite composite, to the dentine of forty extracted human permanent first and second molars were determined after the test specimens were stored in physiological saline at 37 degrees C for 48 hours, one week, two weeks and four weeks, respectively. A shear load was applied to the base of the bonded composite cylinders with a knife-edged rod at a crosshead speed of 0.5 mm/minute. The shear bond strengths were expressed in megapascals (MPa). The quantitative microleakage of Class V preparations in dentine (cementum) in forty-eight extracted human maxillary permanent canines restored with the same dentinal bonding system and after storage in physiological saline at 37 degrees C for the same time intervals as for the shear bond strength tests, was determined. On the final day of each time interval the teeth were thermocycled X 500 in a 2 per cent methylene blue solution between 8 degrees C and 50 degrees C with a dwell time of 15 seconds. Microleakage was determined by a spectrophotometric dye-recovery method and expressed in microgram dye/restoration. There was a significant trend for the shear bond strengths to increase with duration of storage (p = 0.01) but the quantitative microleakage was not significantly different (p = 0.75). 相似文献
4.
J. L. Portefaix M. Cattenot M. Guerriche J. Thivolle-Cazat M. Breysse 《Catalysis Today》1991,10(4):473-487
The objective of this work was to provide comprehensive hypotheses concerning the mechanisms operative in the C---N bond cleavages occurring during the catalytic conversion of amines over a conventional hydrotreating catalyst, so as to account for experimental observations and to help in developing better hydrodenitrogenation catalysts. The approach consists in a study of the relations between the structure and the reactivity of two series of amines with different numbers of hydrogen atoms on the carbon atoms in the and β positions with respect to their nitrogen atom. It was found that the hydrogen atoms on the carbon atom in the β position are involved in the formation of hydrocarbons, and that neither the hydrogen atoms on the carbons in the position nor those on the carbon atoms in the β position are involved in the formation of condensation products. On the basis of these results, two mechanisms are proposed for the formation of the different reaction products. 相似文献
5.
We have applied near-edge X-ray absorption fine structure (NEXAFS) to characterize the surface and bulk properties of LixNi1–xO catalysts. In our experimental set-up, NEXAFS spectra of powder materials could be obtained by measuring the intensity of either electron-yield or fluorescence-yield. While the electron-yield method is sensitive only to the top few atomic layers, the fluorescence-yield method can detect species up to a few thousands angstroms deep into the bulk structure. The ability to distinguish surface and bulk compositions is demonstrated in studies of a number of Li0.5Ni0.5O samples, of which the surface compositions vary as a function of preparation procedures. In addition, NEXAFS investigations following the reaction of LixNi1–xO with CH4 have also been carried out and the results indicate that the initial surface reaction intermediates are Li2CO3. 相似文献
6.
P. Da Costa C. Potvin J.-M. Manoli M. Breysse G. Djega-Mariadassou 《Catalysis Letters》2003,86(1-3):133-138
Hydrodesulfurization (HDS) of 4,6-dimethyldibenzothiophene on alumina-supported Mo2C has been studied. These catalysts are stable and active under deep HDS conditions (0-250 wt ppm S). However, although they are well known to have hydrogenation properties, they lead preferentially to a non-hydrogenated product of the HDS reaction: dimethylbiphenyl. For the same reaction, supported platinum and sulfided molybdenum oxide lead to the hydrogenated products dimethyldicyclohexyl and methylcyclohexyltoluene, respectively. The ranking of HDS activity is as follows: MoS2/Al2O3 < Mo2C/Al2O3 < Pt/SiO2. 相似文献
7.
Support effects on hydrotreating catalysts 总被引:5,自引:0,他引:5
8.
Gruffat D De La Torre A Chardigny JM Durand D Loreau O Sébédio JL Bauchart D 《Lipids》2003,38(2):157-163
Hepatic metabolism of the two main isomers of CLA (9cis-11 trans, 10trans-12cisC18∶2) was compared to that of oleic acid (representative of the main plasma FA) in 16 rats by using the in vitro method of incubated liver slices. Liver tissue samples were incubated at 37°C for 17h under an atmosphere of 95% O2/5%CO2 in a medium supplemented with 0.75 mM of FA mixture (representative of circulating nonesterified FA) and with 55 μM [1-14C]9cis-11 trans C18∶2, [1-14C]10trans-12cis C18∶2, or [1-14C]oleate. The uptake of CLA by hepatocytes was similar for both isomers (9%) and was three times higher (P<0.01) than for oleate (2.6%). The rate of CLA isomer oxidation was two times higher (49 and 40% of incorporated amounts of
9cis-11 trans and 10trans-12 cis, respectively) than that of oleate (P<0.01). Total oxidation of oleate and CLA isomers into [14CO2] was low (2 to 7% of total oxidized FA) compared to the partial oxidation (93 to 98%) leading to the production of [14C] acid-soluble products. CLA isoemrs escaping from catabolism were both highly desaturated (26.7 and 26.8%) into conjugated
18∶3. Oleate and CLA isomers were mainly esterified into neutral lipids (30%). They were slowly secreted as parts of VLDL
particles (<0.4% of FA incorporated into cells), the extent of secretion of oleate and of 10trans-12 cis being 2.2-fold higher than that of 9cis-11 trans (P<0.02). In conclusion, this study clearly showed that both CLA isomers were highly catabolized by hepatocytes, reducing their
availability for peripheral tissues. Moreover, more than 25% of CLA escaping from catabolism was converted into conjugated
18∶3, the biological properties of which remain to be elucidated. 相似文献
9.
10.
Mihaela Habeanu Agnès Thomas Esperanza Bispo Mylène Gobert Dominique Gruffat Denys Durand Dominique Bauchart 《Meat science》2014
The effects of extruded linseed and rapeseed on lipids and FA composition of total, polar and neutral lipids of longissimus thoracis (LT) and semitendinosus (ST) muscles were investigated in 21 Normand cull cows. Animals were assigned in a 100d finishing period to straw (30%) and concentrate (70%) based (C) or the same diet supplemented with linseed (L) or with rapeseed (66%) plus linseed (33%) (RL). Beef polar and neutral lipids were purified by liquid chromatography and their FA analysed by GLC. Trans and cis 18:1, purified by HPLC from total FA methyl esters, were analysed by GLC–MS. L and LR diets did not increase beef lipid deposition, but had modified FA composition of both LT and ST muscles in favouring deposition of 18:3n-3 and 9cis,11tr 18:2 (CLA), mainly to the detriment of 18:1?9 cis (neutral lipids) and 18:2n-6 (polar lipids). However, they did not favour deposition of LC n-3 PUFA in the two muscles, but had increased deposition of trans 18:1 significantly, especially of ?13tr to ?16tr isoforms to the detriment of ?10tr 18:1 (L diet) and of ?11tr 18:1 (RL diet). 相似文献