全文获取类型
收费全文 | 378篇 |
免费 | 19篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 5篇 |
综合类 | 3篇 |
化学工业 | 144篇 |
机械仪表 | 1篇 |
建筑科学 | 22篇 |
能源动力 | 4篇 |
轻工业 | 43篇 |
石油天然气 | 1篇 |
无线电 | 11篇 |
一般工业技术 | 65篇 |
冶金工业 | 85篇 |
原子能技术 | 1篇 |
自动化技术 | 14篇 |
出版年
2023年 | 1篇 |
2022年 | 7篇 |
2021年 | 15篇 |
2020年 | 8篇 |
2019年 | 3篇 |
2018年 | 8篇 |
2017年 | 7篇 |
2016年 | 14篇 |
2015年 | 13篇 |
2014年 | 6篇 |
2013年 | 20篇 |
2012年 | 21篇 |
2011年 | 17篇 |
2010年 | 25篇 |
2009年 | 11篇 |
2008年 | 15篇 |
2007年 | 22篇 |
2006年 | 9篇 |
2005年 | 18篇 |
2004年 | 10篇 |
2003年 | 10篇 |
2002年 | 6篇 |
2001年 | 5篇 |
2000年 | 6篇 |
1999年 | 6篇 |
1998年 | 27篇 |
1997年 | 18篇 |
1996年 | 8篇 |
1995年 | 11篇 |
1994年 | 4篇 |
1993年 | 7篇 |
1992年 | 4篇 |
1991年 | 3篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 4篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 5篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1969年 | 1篇 |
1916年 | 1篇 |
排序方式: 共有399条查询结果,搜索用时 15 毫秒
51.
Philip E. Pfeffer Francis E. Luddy Joseph Unruh James N. Shoolery 《Journal of the American Oil Chemists' Society》1977,54(9):380-386
High resolution natural abundance 13C Fourier transform nuclear magnetic resonance (NMR) has been found to be an effective
tool for the rapid and direct determination of the cis/trans composition in partially hydrogenated and isomerized unsaturated
lipids. With the eis and trans allylic carbon resonances as representative probes for double bond stereo-chemistry. Evaluation
of the cis/trans composition of complex, positionally isomerized mixtures can be made without the necessity of carrying out
detailed analyses of multishift olefinic carbon resonances. Migration of double bonds in monoenes and polyenes and formation
of conjugated unsaturation in cata-lytically treated fats are discussed and assessed as possible sources of error in the evaluation
of cis/trans isomer ratios. Carbon spin lattice relaxation times T1 were measured for both cis and trans allylic reson-ances in isomeric mixtures of varying composition to assure quantitative
intensity relationships. 13C NMR compositional analysis of complex mixtures is demonstrated. 相似文献
52.
Hsiao-Wei Wen Wlodzimierz Borejsza-Wysocki Thomas R. DeCory Antje J. Baeumner Richard A. Durst 《European Food Research and Technology》2005,221(3-4):564-569
In this study, conditions for extracting the major peanut allergen (Ara h1) from chocolate were optimized, and the extracted samples were analyzed by a lateral flow assay (LFA) using liposomal nanovesicles. The optimal conditions using peanut-spiked chocolate were found to be extraction with a mixture of phosphate buffered saline and hexane for 30 min at 35 °C. After centrifugation, the buffer portion was treated with insoluble poly(vinylpolypyrrolidone) to remove phenolic compounds, and then analyzed by the LFA. The entire analysis, including sample preparation and LFA, could be easily completed within 2 h, and the detection limit was 158 g of peanuts/g of chocolate. 相似文献
53.
Antioxidants, preferentially those of dietary origin, have for a long time been considered to help against diseases that are presumably aggravated by oxidative stress, such as cardiovascular diseases, cancer, and neurodegenerative disorders. The outcome of clinical trials undertaken to corroborate this hypothesis, however, remained largely inconclusive. Evidence is now emerging that some dietary "antioxidants" influence signaling pathways and the expression of genes relevant in atherosclerosis by mechanisms other than antioxidative ones. By concrete examples we show that (1) vitamin E has gene regulatory functions which might be more important than acting as an antioxidant in vivo, (2) selenium itself is not an antioxidant at all, and even not in general when incorporated into glutathione peroxidases, and (3) a moderate oxidative stress is beneficial rather than detrimental since it can induce defense mechanisms counteracting xenobiotic and oxidative stress. Thus, there is only a future for antioxidants in the prevention of any disease if their real mechanism of action is considered and suitable read-outs and biomarkers are established. 相似文献
54.
55.
Biological properties of recombinant alpha-interferons: 40th anniversary of the discovery of interferons 总被引:2,自引:0,他引:2
LM Pfeffer CA Dinarello RB Herberman BR Williams EC Borden R Bordens MR Walter TL Nagabhushan PP Trotta S Pestka 《Canadian Metallurgical Quarterly》1998,58(12):2489-2499
IFNs were first described as potent antiviral agents 40 years ago, and recombinant IFN-alpha2a and IFN-alpha2b were approved for the treatment of hairy cell leukemia just 11 years ago. Today, alpha-IFNs are approved worldwide for the treatment of a variety of malignancies and virologic diseases. Although the exact mechanism of action of IFN-alpha in the treatment of such diseases is not fully understood, many advances have been made in the characterization of the physicochemical and diverse biological properties of this highly pleiotropic cytokine. Here we review recent developments in our understanding of the antiviral and immunoregulatory properties of IFN-alpha, the nature of the multisubunit IFN-alpha receptor, and the molecular mechanisms of signal transduction. Where available, we have included comparative data on recombinant alpha-IFNs derived from both naturally occurring and nonnaturally occurring synthetic genes. We also review clinical data and data on the side effects and antigenicity of different sources of recombinant alpha-IFNs in humans. These latter topics are of clinical interest, because they may potentially affect the efficacy of these various products. Hopefully, what is already known about IFN will prompt further exploration into the mechanism(s) of action of IFN-alpha and thus deliver new applications for this prototypic cytokine, whose full therapeutic potential is yet to be realized. 相似文献
56.
57.
58.
59.
非磁性粘性颗粒在添加磁性大颗粒磁场流化床中的流化性能 总被引:3,自引:0,他引:3
通过添加磁性大颗粒,破碎活塞及沟流,显著改善了非磁性粘性颗粒在磁场流化床中的流化性能。为了评价非磁性粘性颗粒在磁场流化床中的流化性能,测量了最小流化速度、床层压力降和床膨胀高度。实验结果表明,非磁性粘性颗粒的最小流化速度,由于添加磁性大颗粒,而显著降低。磁性大颗粒添加量对非磁性粘性颗粒的最小流化速度有较大影响,随磁性大颗粒添加量的增加,最小流化速度降低,但当磁性大颗粒添加量增大到40%后,非磁性粘性颗粒和磁性大颗粒的混合物的最小流化速度就不再降低。 相似文献
60.
This is the first part of a series of two papers to study the agglomeration phenomenon which causes destabilization of certain low and high temperature fluidized beds. A theoretical model is proposed to determine the conditions under which defluidization occurs in fluidized beds in which cohesion forces between granules arise due to the presence of sticky fluids and/or high temperatures. Such bonding mechanisms between particles as solid—liquid bridges, visco-elastic flattening and high temperature sintering are considered. The theoretical model predicts breakup of aggregates in the bed due to forces generated by bubble motion. The theoretical results are compared with experimental measurements in Part II of the paper. 相似文献