全文获取类型
收费全文 | 136篇 |
免费 | 6篇 |
专业分类
电工技术 | 5篇 |
化学工业 | 42篇 |
机械仪表 | 2篇 |
建筑科学 | 6篇 |
轻工业 | 16篇 |
无线电 | 11篇 |
一般工业技术 | 13篇 |
冶金工业 | 36篇 |
原子能技术 | 1篇 |
自动化技术 | 10篇 |
出版年
2023年 | 1篇 |
2022年 | 8篇 |
2021年 | 7篇 |
2020年 | 3篇 |
2019年 | 3篇 |
2018年 | 1篇 |
2016年 | 9篇 |
2015年 | 1篇 |
2014年 | 3篇 |
2013年 | 6篇 |
2012年 | 11篇 |
2011年 | 8篇 |
2010年 | 1篇 |
2009年 | 5篇 |
2008年 | 5篇 |
2007年 | 3篇 |
2006年 | 3篇 |
2005年 | 6篇 |
2003年 | 2篇 |
2001年 | 8篇 |
1999年 | 3篇 |
1998年 | 6篇 |
1997年 | 7篇 |
1996年 | 8篇 |
1995年 | 7篇 |
1994年 | 2篇 |
1993年 | 3篇 |
1990年 | 4篇 |
1987年 | 2篇 |
1984年 | 1篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
排序方式: 共有142条查询结果,搜索用时 15 毫秒
81.
The purpose of this paper is to determine by experiment whether Mn11Si19 and Mn4Si7 in their bulk states have a finite magnetic moment or not. Magnetisation measurements were carried out on these materials using both SQUID system and Kerr rotation system. The high quality samples were grown using the temperature gradient solution growth method. SQUID measurements revealed that Mn11Si19 has finite magnetism while Mn4Si7 does not in their bulk states. It was also confirmed that Mn4Si7 became magnetic and Mn11Si19 got to exhibit a distinctive hysteresis in their powdery state. The enhancement of magnetism implied that the surface of the samples was to a great extent linked to its magnetism. 相似文献
82.
83.
Solaro R Chiellini F Signori F Fiumi C Bizzarri R Chiellini E 《Journal of materials science. Materials in medicine》2003,14(8):705-711
The preparation and characterization of nanoparticles based on biodegradable/bioerodible polymers is reported. They have been designed for the controlled-targeted release of proteic drugs such as -interferon and for the release of active principles in tissue engineering. The amenability of some of the prepared polymeric matrices to be used in the fabrication of micro and nano patterned scaffolds is also described. 相似文献
84.
F. M. d’Heurle A. Gangulee C. F. Aliotta V. A. Ranieri 《Journal of Electronic Materials》1975,4(3):497-515
Aluminum thin film conductors containing Mg alloying additions have been tested for electromigration failure by formation
of electrically open circuits. The test conditions were either 2 × 106 A/cm2 or 4 × 106 A/cm2 for the current density, and either 175 or 225°C for the temperature. The median lifetimes were found to increase with increasing
Mg concentrations up to the highest concentration tested, about 6%. With polycrystalline films the maximum increase in lifetime
resulting from Mg additions corresponds to a factor of about 100, as compared to pure Al films. This is about equal to previously
reported results obtained with Cu additions. The increase in lifetime has been shown to result from a decrease in the rate
of grain boundary diffusion for the Al atoms. Magnesium atoms diffuse at approximately the same rate as Al atoms. Thus the
mechanism of failure formation in Al films containing Mg is thought to be different than in Al-Cu films, where Cu atoms diffuse
faster than Al atoms and failure ensues upon local Cu depletion. 相似文献
85.
Monticone M Tonachini L Tavella S Degan P Biticchi R Palombi F Puglisi R Boitani C Cancedda R Castagnola P 《Reproduction (Cambridge, England)》2007,134(3):483-492
Mtfr1/Chppr is a nuclear gene coding for a mitochondrial protein capable of inducing fission of this organelle in a sequence-specific manner. Here we show that in mice, Mtfr1/Chppr is ubiquitously expressed and displays the highest level of expression in pubertal and adult testes and in particular in spermatids and Leydig cells. To investigate Mtfr1 function in vivo, we analyzed homozygous mice null for this gene obtained through a gene trap approach. We show that these mice fail to express Mtfr1 and that in their testes several genes coding for enzymes involved in the defense against oxidative stress are downregulated. Among these, we studied in particular glutathione peroxidase 3 and show its expression in selected testis cell types. Furthermore, we demonstrate oxidative DNA damage specifically in testes of Mtfr1-deficient mice likely resulting from a reduced antioxidant activity. As a whole, these data suggest that Mtfr1 protects the male gonads against oxidative stress. 相似文献
86.
V. Goffredo M. W. Falk E. D. Schroeder R. L. Irvine E. Ranieri 《Canadian Metallurgical Quarterly》2009,135(2):101-104
Typically, microbes associated with biological wastewater treatment processes are subjected to dynamic organic and nutrient loading conditions. This constantly changing environment imposes a stress, referred to as “feast-famine” that selects for microbes capable of biologically storing substrates as polymers during high organic concentration periods (i.e., feast) for use during periods of low organic availability (i.e., famine). In this study, we monitored the production of biostorage polymers generated with actual cheese wastewater treatment by way of sequencing batch reactors (SBRs). SBRs were employed and operated in duplicate under two long (i.e., hours) filling scenarios (1) “react fill” with mixing/aeration and (2) “static fill” with no mixing/aeration. Despite comparable effluent water quality levels, the results reveal that a “static fill” approach outperforms a “react fill” with respect to maximum biostorage polymer production (50% more poly-β-hydroxybutyrate, 15% more glycogen). The presence of biostorage polymer production has been shown to be indicative of a more stable and robust process. 相似文献
87.
Luisa Gesualdi Erica Leonetti Alessandra Cucina Bianca Maria Scicchitano Silvia Sorrentino Maria Grazia Tarsitano Andrea Isidori Mariano Bizzarri Antonio Filippini Anna Riccioli Marcella Cammarota Vincenzo Gigantino Giulia Ricci Angela Catizone 《International journal of molecular sciences》2020,21(22)
Overactivation of the c-MET/HGF system is a feature of many cancers. We previously reported that type II testicular germ cell tumor (TGCT) cells express the c-MET receptor, forming non-seminomatous lesions that are more positive compared with seminomatous ones. Notably, we also demonstrated that NT2D1 non-seminomatous cells (derived from an embryonal carcinoma lesion) increase their proliferation, migration, and invasion in response to HGF. Herein, we report that HGF immunoreactivity is more evident in the microenvironment of embryonal carcinoma biopsies with respect to seminomatous ones, indicating a tumor-dependent modulation of the testicular niche. PI3K/AKT is one of the signaling pathways triggered by HGF through the c-MET activation cascade. Herein, we demonstrated that phospho-AKT increases in NT2D1 cells after HGF stimulation. Moreover, we found that this pathway is involved in HGF-dependent NT2D1 cell proliferation, migration, and invasion, since the co-administration of the PI3K inhibitor LY294002 together with HGF abrogates these responses. Notably, the inhibition of endogenous PI3K affects collective cell migration but does not influence proliferation or chemotactic activity. Surprisingly, LY294002 administered without the co-administration of HGF increases cell invasion at levels comparable to the HGF-administered samples. This paradoxical result highlights the role of the testicular microenvironment in the modulation of cellular responses and stimulates the study of the testicular secretome in cancer lesions. 相似文献
88.
Acrylic and methacrylic monomers bearing pyrrolyl, thienyl and terthienyl groups, were synthesized and copolymerized with various amounts of butyl acrylate and butyl methacrylate. In the resulting copolymers the heterocycle side‐groups behaved as initiators in the oxidative polymerization of thiophene, allowing the polythiophene chains to grow from the side‐groups and leading therefore to graft copolymers. These last were collected mostly as insoluble fractions after extraction with chloroform. Processible polymers with polythiophene side‐chains were obtained when in the precursor polymer the heterocycle side‐group content was very low. The presence in the graft copolymers of a significant number of stiff polythiophene side‐chains was responsible for the rise in Tg values in comparison with the precursor polymers. The average number of grafted thiophene units, evaluated in the range 2–7.5, did not relate directly to measured conductivity values that were in the range 5.9 × 10−5–6.2 × 10−2 S cm−1. © 1999 Society of Chemical Industry 相似文献
89.
Tjelta T. Nordbotten A. Annoni M. Scarrone E. Bizzarri S. Tokarchuk L. Bigham J. Adams C. Craig K. Dinis M. 《Communications Magazine, IEEE》2001,39(8):56-63
The current challenge in radio networks is to provide integrated broadband services to everybody. The realization of this goal is dependent on both the development of products for the mass market and the improvement of the systems that support these products. New cellular mobile, fixed terrestrial, and satellite systems are being developed to provide broadband integrated services. The users of these new systems will not need, or even want, to know which particular systems are used to access the requested services. The users may negotiate terms of delivery, such as data rate and quality of service, but the actual system of delivery should be transparent. In order to both achieve transparent service delivery and ensure efficient use of the radio frequency spectrum, a flexible and scaleable resource management system is needed. This article highlights the development trends that will form the basis of future network systems and presents some suggestions for the management and control of these systems 相似文献
90.
Dinicola S Cucina A Pasqualato A D'Anselmi F Proietti S Lisi E Pasqua G Antonacci D Bizzarri M 《International journal of molecular sciences》2012,13(1):651-664
Grape seed extract has been proven to exert anticancer effects on different tumors. These effects are mainly ascribed to catechin and procyanidin content. Analytical studies demonstrated that grape seed extract composition is complex and it is likely other components could exert biological activities. Using cell count and flow cytometry assays, we evaluated the cytostatic and apoptotic effects produced by three different grape seed extracts from Italia, Palieri and Red Globe cultivars, on Caco2 and HCT-8 colon cancer cells. These effects were compared to those induced by epigallocatechin and procyanidins, alone or in association, on the same cell lines. All the extracts induced growth inhibition and apoptosis in Caco2 and HCT-8 cells, along the intrinsic apoptotic pathway. On both cell lines, growth inhibition induced by Italia and Palieri grape seed extracts was significantly higher than that it has been recorded with epigallocatechin, procyanidins and their association. In Caco2 cells, the extract from Red Globe cultivar was less effective in inducing growth inhibition than procyanidins alone and in association with epigallocatechin, whereas, in HCT-8 cells, only the association of epigallocatechin and procyanidins triggers a significant proliferation decrease. On both cell lines, apoptosis induced by Italia, Palieri and Red Globe grape seed extracts was considerably higher than has been recorded with epigallocatechin, procyanidins and their association. These data support the hypothesis by which other compounds, present in the grape seed extracts, are likely to enhance the anticancer effects. 相似文献