全文获取类型
收费全文 | 251篇 |
免费 | 6篇 |
专业分类
电工技术 | 9篇 |
化学工业 | 39篇 |
金属工艺 | 1篇 |
机械仪表 | 1篇 |
建筑科学 | 5篇 |
矿业工程 | 3篇 |
能源动力 | 15篇 |
轻工业 | 11篇 |
水利工程 | 2篇 |
无线电 | 90篇 |
一般工业技术 | 26篇 |
冶金工业 | 25篇 |
原子能技术 | 4篇 |
自动化技术 | 26篇 |
出版年
2023年 | 1篇 |
2022年 | 1篇 |
2021年 | 8篇 |
2020年 | 3篇 |
2019年 | 1篇 |
2018年 | 2篇 |
2017年 | 3篇 |
2016年 | 5篇 |
2015年 | 3篇 |
2014年 | 8篇 |
2013年 | 12篇 |
2012年 | 11篇 |
2011年 | 13篇 |
2010年 | 9篇 |
2009年 | 4篇 |
2008年 | 8篇 |
2007年 | 10篇 |
2006年 | 13篇 |
2005年 | 13篇 |
2004年 | 7篇 |
2003年 | 9篇 |
2002年 | 11篇 |
2001年 | 11篇 |
2000年 | 8篇 |
1999年 | 8篇 |
1998年 | 23篇 |
1997年 | 4篇 |
1996年 | 4篇 |
1995年 | 8篇 |
1994年 | 6篇 |
1993年 | 7篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1990年 | 4篇 |
1989年 | 5篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1984年 | 2篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1976年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有257条查询结果,搜索用时 31 毫秒
51.
Increased number of cardiomyocytes in cross-sections from tachycardia-induced cardiomyopathic hearts
S Jovanovic AJ Grantham JE Tarara JC Burnett A Jovanovic A Terzic 《Canadian Metallurgical Quarterly》1999,3(2):153-155
Based on positive identification of DNA replication and mitotic division in cardiomyocytes isolated from failing hearts, it has been proposed that adult ventricular cardiomyocytes can gain the capacity to proliferate with progression of heart failure. However, due to the lack of a reliable method to distinctly image individual cardiac cells within the myocardial syntitium, such a concept still remains largely controversial. In the present study, we used laser confocal microscopy, to image cross-sections of intact myocardium stained with fluorescein-conjugated wheat germ agglutinin and propidium iodide. This approach allowed to clearly separate the profile of individual myocytes within cardiac tissue sections. We found that in the left ventricles of dogs, subjected to tachycardia-induced cardiomyopathy, the number of cells was significantly increased in both longitudinal and transversal sections. Treatment with the angiotensin-converting enzyme inhibitor, enalapril, reversed these changes to values similar to those found in controls. Therefore, this study provides evidence, at the in situ level, for cellular hyperplasia in heart failure. This supports the more general notion that adult cardiomyocytes may not be terminally differentiated, and that an increase in cell number could contribute to the increase in left ventricular mass observed with progression of disease. 相似文献
52.
Marius-Alexandru Beleaua Ioan Jung Cornelia Braicu Doina Milutin Simona Gurzu 《International journal of molecular sciences》2021,22(21)
Although skin melanoma (SKM) represents only one-quarter of newly diagnosed skin malignant tumors, it presents a high mortality rate. Hence, new prognostic and therapeutic tools need to be developed. This study focused on investigating the prognostic value of the subcellular expression of BRAF, KRAS, and KIT in SKM in correlation with their gene-encoding interactions. In silico analysis of the abovementioned gene interactions, along with their mRNA expression, was conducted, and the results were validated at the protein level using immunohistochemical (IHC) stains. For IHC expression, the encoded protein expressions were checked on 96 consecutive SKMs and 30 nevi. The UALCAN database showed no prognostic value for the mRNA expression level of KRAS and BRAF and demonstrated a longer survival for patients with low mRNA expression of KIT in SKMs. IHC examinations of SKMs confirmed the UALCAN data and showed that KIT expression was inversely correlated with ulceration, Breslow index, mitotic rate, and pT stage. KRAS expression was also found to be inversely correlated with ulceration and perineural invasion. When the subcellular expression of BRAF protein was recorded (nuclear vs. cytoplasmatic vs. mixed nucleus + cytoplasm), a direct correlation was emphasized between nuclear positivity and lymphovascular or perineural invasion. The independent prognostic value was demonstrated for mixed expression of the BRAF protein in SKM. BRAF cytoplasmic predominance, in association with KIT’s IHC positivity, was more frequently observed in early-stage nonulcerated SKMs, which displayed a low mitotic rate and a late death event. The present study firstly verified the possible prognostic value of BRAF subcellular localization in SKMs. A low mRNA expression or IHC cytoplasmic positivity for KIT and BRAF might be used as a positive prognostic parameter of SKM. SKM’s BRAF nuclear positivity needs to be evaluated in further studies as a possible indicator of perineural and lymphovascular invasion. 相似文献
53.
The aim of this article was to investigate the effect of a NaA‐type zeolite on a polydimethylsiloxane (PDMS)–zeolite composite. The obtained results show that the introduction of a NaA‐type zeolite into polysiloxane matrices results in a change of the equilibrium degree of swelling (DSe) of composites in toluene, their hardness, and their thermal stability. With increase in the zeolite, the time required to achieve the DSe is reduced, DSe decreases, and hardness increases. A double effect of the zeolite concentration on the change of the composite characteristics was noted. At zeolite concentrations of up to 20%, there is a drastic change of the DSe and hardness with zeolite concentration, while this effect is considerably less pronounced at higher concentrations. The results obtained show that a NaA‐type zeolite plays the role of a reinforcing filler. A new mechanism of bonding the zeolite into the composite was suggested. According to this model, there is a possibility that bonds are established between the polymer and the zeolite via interaction of the π‐bond of terminal vinyl groups of PDMS with the Na cation of the zeolite. With increase in the zeolite concentration in the composite, the total number of established polymer–zeolite bonds increases, but the density of the interaction decreases. This explains the change in the characteristics of the composite with the change of zeolite concentration. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1171–1176, 2000 相似文献
54.
Owens C Zisser H Jovanovic L Srinivasan B Bonvin D Doyle FJ 《IEEE transactions on bio-medical engineering》2006,53(6):996-1005
Run-to-run control has been applied to several traditional batch processes in the chemical industry. The 24-h cycle of eating meals, measuring blood glucose concentrations, and delivering the correct insulin bolus, with the goal of achieving the optimal blood glucose profile, can be viewed in the same spirit as traditional batch processes such as emulsion polymerization. In this paper, we aim to exploit the "repetitive" nature of the insulin therapy of people with Type 1 diabetes. A run-to-run algorithm is used on a virtual diabetic patient model to control blood glucose concentrations. The insulin input is parameterized into the timing and amount of the dose while the glucose output is parameterized into the maximum and minimum glucose concentrations. Robustness of the algorithm to variations in the meal amount, meal timing, and insulin sensitivity parameter is addressed. In general, the algorithm is able to converge when the meal timing is varied within +/- 40 min. If the meal size is underestimated by approximately 10 grams (g), the algorithm is able to converge within a reasonable time frame for breakfast, lunch, and dinner. If the meal size is overestimated by 20-25 g, the algorithm is able to converge. When random variations in the meal timing and the meal amount are introduced, the variation on the output variables, Gmax and Gmin, scales according to the amount of variation allowed. Along with this, the insulin sensitivity of the virtual patient model is varied. The algorithm is robust for differences in insulin sensitivity less than +/- 50% of the nominal value. 相似文献
55.
Obradovic B Stojkovska J Jovanovic Z Miskovic-Stankovic V 《Journal of materials science. Materials in medicine》2012,23(1):99-107
Alginate colloid solution containing electrochemically synthesized silver nanoparticles (AgNPs) was investigated regarding
the nanoparticle stabilization and possibilities for production of alginate based nanocomposite hydrogels in different forms.
AgNPs were shown to continue to grow in alginate solutions for additional 3 days after the synthesis by aggregative mechanism
and Ostwald ripening. Thereafter, the colloid solution remains stable for 30 days and could be used alone or in mixtures with
aqueous solutions of poly(vinyl alcohol) (PVA) and poly(N-vinyl-2-pyrrolidone) (PVP) while preserving AgNPs as verified by UV–Vis spectroscopy studies. We have optimized techniques
for production of Ag/alginate microbeads and Ag/alginate/PVA beads, which were shown to efficiently release AgNPs decreasing
the Escherichia coli concentration in suspensions for 99.9% over 24 h. Furthermore, Ag/hydrogel discs based on alginate, PVA and PVP were produced
by freezing-thawing technique allowing adjustments of hydrogel composition and mechanical properties as demonstrated in compression
studies performed in a biomimetic bioreactor. 相似文献
56.
57.
Kusljevic M. D. Tomic J. J. Jovanovic L. D. 《IEEE transactions on instrumentation and measurement》2010,59(2):322-329
58.
59.
Marija V. Pergal Vesna V. Antić Milutin N. Govedarica Dejan Goäevac Sanja Ostojić Jasna Djonlagić 《应用聚合物科学杂志》2011,122(4):2715-2730
Novel polyurethane copolymers derived from 4,4′‐methylenediphenyl diisocyanate (MDI), 1,4‐butanediol (BD) and α,ω‐dihydroxy‐[poly(caprolactone)‐poly (dimethylsiloxane)‐poly(caprolactone)] (α,ω‐dihydroxy‐(PCL‐PDMS‐PCL); = 6100 g mol?1) were synthesized by a two‐step polyaddition reaction in solution. In the synthesis of the polyurethanes, the PCL blocks served as a compatibilizer between the nonpolar PDMS blocks and the polar comonomers, MDI and BD. The synthesis of thermoplastic polyurethanes (TPU) with high soft segment contents was optimized in terms of the concentrations of the reactants, the molar ratio of the NCO/OH groups, and the time and temperature of the polyaddition reaction. The structure, composition, and hard MDI/BD segment length of the synthesized polyurethane copolymers were determined by 1H, 13C‐NMR, and two‐dimensional correlation (COSY, HSQC, and HMBC) spectroscopy, while the hydrogen bonding interactions in the copolymers were analyzed by FT‐IR spectroscopy. The influence of the reaction conditions on the structure, molecular weight, thermal, and some physical properties was studied at constant composition of the reaction mixture. A change in the molar ratio of the NCO/OH groups and the reaction conditions modified not only the molecular weight of the synthesized polyurethanes, but also the microstructure and therefore the thermal and physical properties of the copolymers. It was demonstrated that only PCL segments with high soft segment contents crystallize, thereby showing spherulitic morphology. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 相似文献
60.
Gordana Jovanovic Dolecek Alfonso Fernandez-Vazquez 《AEUE-International Journal of Electronics and Communications》2013,67(5):387-396
This paper presents a novel two-stage comb decimator with the improved magnitude characteristic. Simple multiplierless corrector filters, which are designed using the frequency sampling and IFIR methods, are introduced. The proposed filters compensate the comb passband droop in the wideband passband region and increase the attenuations in the folding bands. Using the multirate identity the filters may be moved to a lower rate. The filter design depends only on the number of the cascaded comb filters and do not depend on the decimation factor M. 相似文献