全文获取类型
收费全文 | 308篇 |
免费 | 17篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 3篇 |
化学工业 | 72篇 |
金属工艺 | 1篇 |
机械仪表 | 10篇 |
建筑科学 | 30篇 |
能源动力 | 9篇 |
轻工业 | 55篇 |
水利工程 | 5篇 |
无线电 | 21篇 |
一般工业技术 | 47篇 |
冶金工业 | 24篇 |
自动化技术 | 49篇 |
出版年
2024年 | 1篇 |
2023年 | 3篇 |
2022年 | 10篇 |
2021年 | 10篇 |
2020年 | 9篇 |
2019年 | 4篇 |
2018年 | 7篇 |
2017年 | 6篇 |
2016年 | 11篇 |
2015年 | 10篇 |
2014年 | 16篇 |
2013年 | 26篇 |
2012年 | 20篇 |
2011年 | 28篇 |
2010年 | 10篇 |
2009年 | 18篇 |
2008年 | 13篇 |
2007年 | 21篇 |
2006年 | 8篇 |
2005年 | 13篇 |
2004年 | 5篇 |
2003年 | 11篇 |
2002年 | 6篇 |
2001年 | 6篇 |
2000年 | 3篇 |
1999年 | 4篇 |
1998年 | 17篇 |
1997年 | 4篇 |
1996年 | 5篇 |
1995年 | 4篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1992年 | 3篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1978年 | 1篇 |
1976年 | 2篇 |
1975年 | 1篇 |
排序方式: 共有326条查询结果,搜索用时 15 毫秒
31.
32.
Using Shewart charts to control multicavity processes is not, in general, reliable when there are small deviations in relation to the total variability and when there is a large number of cavities. For this reason EWMA charts have been used to control averages and standard deviations in some of the cavities. The quantification of the improvement in the reliability of the processes has been done as a result of studying a simulation in which the cycle mean length to detect an out-of-control signal, under different experimental conditions, has been tested. 相似文献
33.
JL Alloza Gascón JL Batalla Cadira JA Salvá Miquel 《Canadian Metallurgical Quarterly》1976,23(138):557-569
Cummulative dose-response curves to l-noradrenaline and in presence of different concentrations of TRH (10(-3), 10(-4), 10(-5), 10(-6), 10(-7), and 10(-8) M) were investigated. 25 segments of vas deferens (escrotal tract) were obtained from different surgical patients of urological disorders. At the lower concentration (greater than 10(-7) M), we can not appreciate any influence of TRH on the l-noradrenaline response. Nevertheless there was a reduction of response to l-noradrenaline, with displacement of the curves to the right side, for the high concentrations, and a proportional ratio to the concentration to TRH. 相似文献
34.
We describe for the first time the ultrastructure of spermiogenesis of a representative of the family Dipylidiidae, Dipylidium caninum. Spermiogenesis begins with the formation of a differentiation zone. This conical area presents two centrioles with associated striated roots. One of the centrioles develops a flagellum and posteriorly a proximodistal fusion is produced between the axoneme and a median cytoplasmic process. In a final stage of spermiogenesis a condensation of electron-dense material between cortical microtubules is observed in the anterior part of the differentiation zone. This is the origin of the crest-like body that appears at the end of spermiogenesis. The presence of striated roots associated with centrioles constitutes the first report of these structures in the spermiogenesis of a cyclophyllidean cestode. 相似文献
35.
Solar drying of garlic with energy storage in silica gel is experimentally simulated in a closed system in which the air is continuously circulated between food and adsorbent. Kinetics of the drying process are studied and equilibrium data are predicted by a mathematical model developed from the experimental results. By comparing the end points of drying with equilibrium values the length of the drying process can be established.From sorption data, a garlic surface area of 63–188 m2 g?1 and a heat of adsorption in the first layer of 2548–2691 kJ kg?1 have been calculated. A value of 746 kJ kg?1 has been deduced for the activation energy for water removal. 相似文献
36.
The specification of human/machine dialogues for general purpose terminals and special purpose consoles in a natural language is difficult and frequently leads to ambiguities and misinterpretations between terminal and dialogue constructors and users. In this paper, the problem of operator console definition is related to the problem of language and language translator definition. An efficient metalanguage tool (TBNF) for the handling of the latter problem is applied to the solution of the first problem. An example from the Telecontrol of a Power Network, being developed at ENHER (Barcelona, Spain), is described as an illustration. 相似文献
37.
The need for sentinel organisms reflecting small-scale changes in heavy metal pollution of different habitats has been previously stated and the role of terrestrial mammalian parasites has been pointed out as an important field of research aiming at the potential use of parasitic models as bioindicators. The scope of the present study was to assess the concentration of some toxic (Cd, Pb, As and Hg) elements in Dunas de Mira (Natura 2000 PTCON055) while testing the model constituted by the wild rabbit (Oryctolagus cuniculus Linnaeus, 1758) and its intestinal cestode parasite Mosgovoyia ctenoides Railliet, 1890 as potential bioindicators. Wild rabbits were harvested by hunters and analysed for intestinal cestodes. Samples of kidney, liver, intestinal mucosa, muscle of host and also M. ctenoides were taken and deep-frozen for posterior element analysis by ICP-MS. In general, levels of contamination in rabbit tissues were found to be low although some of the elements were detected in higher quantities when compared to other previous reports for wildlife in Europe. The highest quantity of Pb was found in rabbit muscle (3.81 ppm) while highest Cd and Hg values were found in kidney (1.02 and 0.08 ppm). Significant linear relationships were found between Pb concentration in the parasite and Pb concentration in kidney (P=0.0047), muscle (P=0.0002) and intestinal mucosa (P=0.0181) and between As concentration in the parasite and As concentration in liver (P=0.0024), kidney (P=0.0010), muscle (P=0.0003) and intestinal mucosa (P=0.0047). The most significant relationships for Pb and As were detected between element concentration in the cestode and in host muscle. However, maximum Pb and As concentrations in M. ctenoides were only twice as high as those found for rabbit kidney and therefore it is not possible to confirm the role of the model O. cuniculus/M. ctenoides as a promising bioindicator system unlike other mammalian host/cestode models tested in other studies. The contrasting results might be due to differences in the absorption processes in the tegument of different cestode families. Furthermore, the large size of the cestodes used in the present study might also explain the relatively low element concentration values obtained. 相似文献
38.
Pierre Miquel Yas Yamin Karine Lombaert Christophe Dujardin Pascal Granger 《Topics in Catalysis》2009,52(13-20):1791-1798
The influence of the support synthesis for the preparation of supported Pd/LaFeO3 perovskite based catalysts and the nature of the palladium precursor on the catalytic performances in the selective reduction of NO to N2 by hydrocarbons have been investigated. According to the preparation method, subsequent surface and bulk characterisation revealed significant changes in the degree of dispersion and the chemical environment of oxidic palladium species depending on the extent of interaction with the support. Pd nitrate precursor leads to the stabilisation of the Pd surface concentration. The metal support interactions thus obtained strongly enhance the catalytic performances, particularly the resistance to thermal ageing whereas sol–gel synthesis produces the higher support activity. 相似文献
39.
40.
Nikolaos Kontoudakis Mireia Esteruelas Francesca Fort Joan Miquel Canals Victor De Freitas Fernando Zamora 《Food chemistry》2011
Nowadays, consumers demand red wines with deep colour, soft tannins and fruit scents, but these wines can only be obtained from grapes with complete phenolic maturity. Diverse methods have been proposed for measuring phenolic maturity. However, all these methods only provide the average value and do not consider any possible heterogeneity. Throughout ripening, grapes were separated according to their density, which revealed the existence of a large heterogeneity. Grapes at harvest were also separated by density in three groups. The higher the density of the grapes the higher ethanol content, pH, colour intensity, total phenolic index and anthocyanin and proanthocyanidin concentrations, and the lower the titratable acidity and bitterness of the wines. When the grapes were denser the wines were also better balanced in flavour and mouthfeel sensation. These results suggest that grape heterogeneity may influence the final wine composition and quality and therefore it should be considered at harvest. 相似文献