全文获取类型
收费全文 | 277篇 |
免费 | 38篇 |
专业分类
电工技术 | 1篇 |
化学工业 | 185篇 |
金属工艺 | 4篇 |
机械仪表 | 4篇 |
建筑科学 | 3篇 |
能源动力 | 5篇 |
轻工业 | 23篇 |
水利工程 | 1篇 |
无线电 | 12篇 |
一般工业技术 | 53篇 |
冶金工业 | 8篇 |
自动化技术 | 16篇 |
出版年
2024年 | 2篇 |
2023年 | 13篇 |
2022年 | 60篇 |
2021年 | 50篇 |
2020年 | 20篇 |
2019年 | 11篇 |
2018年 | 9篇 |
2017年 | 9篇 |
2016年 | 34篇 |
2015年 | 11篇 |
2014年 | 1篇 |
2013年 | 16篇 |
2012年 | 17篇 |
2011年 | 14篇 |
2010年 | 4篇 |
2009年 | 10篇 |
2008年 | 9篇 |
2007年 | 1篇 |
2006年 | 3篇 |
2005年 | 2篇 |
2004年 | 1篇 |
2003年 | 4篇 |
2002年 | 3篇 |
2000年 | 2篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1965年 | 1篇 |
1964年 | 1篇 |
排序方式: 共有315条查询结果,搜索用时 15 毫秒
61.
The object of study is nonlinear stationary controlled system of ordinary differential equations with constant disturbance in the right part. The problem of constructing the synthesising control function providing the transfer of this system from the initial state to the origin is considered. The sufficiently simple for numerical implementation algorithm of solution of the above-mentioned problem is obtained. It is shown that for local null controllability of the considered system, it is sufficient that the conditions of the Kalman's type were satisfied. In addition, the estimates restricting the choice of initial conditions and external disturbances under which the transfer is guaranteed are obtained. The main idea of the method of construction of the desired control function consists in reducing the original problem to stabilisation of a special kind linear non-stationary system and solving the Cauchy problem for an auxiliary system of ordinary differential equations closed by stabilising control. The simplicity of the realisation of this algorithm is determined by the construction of the auxiliary system and its stabilisation that could be obtained by analytical methods. The effectiveness of the method is illustrated by solving the problem of crane control and its numerical simulation. 相似文献
62.
Diana Salikhova Tatiana Bukharova Elvira Cherkashova Daria Namestnikova Georgy Leonov Maria Nikitina Ilya Gubskiy Gevorg Akopyan Andrey Elchaninov Konstantin Midiber Natalia Bulatenco Victoria Mokrousova Andrey Makarov Konstantin Yarygin Vladimir Chekhonin Liudmila Mikhaleva Timur Fatkhudinov Dmitry Goldshtein 《International journal of molecular sciences》2021,22(9)
Transplantation of various types of stem cells as a possible therapy for stroke has been tested for years, and the results are promising. Recent investigations have shown that the administration of the conditioned media obtained after stem cell cultivation can also be effective in the therapy of the central nervous system pathology (hypothesis of their paracrine action). The aim of this study was to evaluate the therapeutic effects of the conditioned medium of hiPSC-derived glial and neuronal progenitor cells in the rat middle cerebral artery occlusion model of the ischemic stroke. Secretory activity of the cultured neuronal and glial progenitor cells was evaluated by proteomic and immunosorbent-based approaches. Therapeutic effects were assessed by overall survival, neurologic deficit and infarct volume dynamics, as well as by the end-point values of the apoptosis- and inflammation-related gene expression levels, the extent of microglia/macrophage infiltration and the numbers of formed blood vessels in the affected area of the brain. As a result, 31% of the protein species discovered in glial progenitor cells-conditioned medium and 45% in neuronal progenitor cells-conditioned medium were cell type specific. The glial progenitor cell-conditioned media showed a higher content of neurotrophins (BDNF, GDNF, CNTF and NGF). We showed that intra-arterial administration of glial progenitor cells-conditioned medium promoted a faster decrease in neurological deficit compared to the control group, reduced microglia/macrophage infiltration, reduced expression of pro-apoptotic gene Bax and pro-inflammatory cytokine gene Tnf, increased expression of anti-inflammatory cytokine genes (Il4, Il10, Il13) and promoted the formation of blood vessels within the damaged area. None of these effects were exerted by the neuronal progenitor cell-conditioned media. The results indicate pronounced cytoprotective, anti-inflammatory and angiogenic properties of soluble factors secreted by glial progenitor cells. 相似文献
63.
Saewon Kang Gill M. Biesold Hansol Lee Daria Bukharina Zhiqun Lin Vladimir V. Tsukruk 《Advanced functional materials》2021,31(42):2104596
This study demonstrates a novel chiral organization of multi-materials from semiconducting quantum nanorods (QNRs) co-assembled into chiral nematic polysaccharide (cellulose) nanocrystals for active manipulation of chiro-optical light emission properties in elastomeric materials. Highly emissive anisotropic QNRs with dimensions and surface chemistry commensurate with those of biological nanocrystals facilitate seamless co-assembly into an integrated chiral nematic organization due to preferable enthalpic interactions and pairing processes. The resulting freestanding highly emissive bio-inorganic elastomeric materials exhibit vivid iridescence and emission with a strong optical activity that manifests itself in active and tunable chiral photoluminescence with unusually large asymmetry. Intriguingly, large-strain reversible mechanical deformation of physically crosslinked elastomers endows fully reversible alternation of helical structural configuration and corresponding linearly and circularly polarized photoluminescence. This study provides a platform to render dynamic optical functionality with reconfigurable light propagation/emission in bio-inorganic elastomers for futuristic applications in chiral lasing, biosensing, optical gauges, and holographic display. 相似文献
64.
Macroporous hydrogels based on chitosan derivatives: Preparation,characterization, and in vitro evaluation 下载免费PDF全文
Tatiana S. Demina Daria S. Zaytseva‐Zotova Tatiana A. Akopova Alexander N. Zelenetskii Elena A. Markvicheva 《应用聚合物科学杂志》2017,134(13)
Chitosan‐based hydrogels are considered as promising biomaterials for tissue engineering. Biological properties of chitosan could be significantly improved by modification of its chemical structure. This study was aimed at characterizing macroporous hydrogels fabricated by freeze‐drying technique from chitosan, which has been N‐acetylated by 2,2‐bis(hydroxymethyl)propionic acid or l ,d ‐lactide. The nature of the acetylated agent was shown to significantly affect hydrogels morphology, swelling behavior, zeta‐potential, and protein sorption as well as their degradation by lysozyme. According to scanning electron and confocal laser scanning microscopy, the hydrogels possessed interconnected macroporous network that facilitated cells penetration into the interior regions of the hydrogel. Chemical modification of chitosan significantly influenced L929 cell growth behavior on hydrogel compared to the non‐modified chitosan. The proposed chemical strategy for modification of chitosan could be considered as promising approach for improvement of chitosan hydrogels. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44651. 相似文献
65.
Xinyu Wang Xinghua Qin Qiongqiong Lu Mingming Han Ahmad Omar Daria Mikhailova 《中国化学工程学报》1982,28(8):2214-2220
Aqueous zinc-ion batteries have been regarded as a promising alternative to large-scale energy storage, due to associated low-cost, improved safety and environmental friendliness. However, a high-performance cathode material for both rate capability and specific capacity is still a challenge. One kind of the more promising candidates are sodium manganese oxide (NMO) materials, although they suffer from individual issues and need to be further improved. Herein, we present a novel mixed phase NMO material composed of nearly equal amounts of Na0.55Mn2O4 and Na0.7MnO2.05. The structured configuration with particle size of 200-500 nm is found to be beneficial towards improving the ion diffusion rate during the charge/discharge process. Compared with Na0.7MnO2.05 and Na0.55Mn2O4, the mixed phase NMO demonstrates an enhanced rate capability and excellent long-term cycling stability with a capacity retention of 83% after 800 cycles. More importantly, the system also delivers an impressive energy density and power density, as 378 W·h·kg-1 at 68.7 W·kg-1, or 172 W·h·kg-1 at 1705 W·kg-1. The superior electrochemical performance is ascribed to the fast Zn2+ diffusion rate because of a large ratio of capacitive contribution (63.9% at 0.9 mV·s-1). Thus, the mixed phase route provides a novel strategy to enhance electrochemical performance, enabling mixed phase NMO as very promising material towards large-scale energy-storage applications. 相似文献
66.
Daria Battini Martina Calzavara Alessandro Persona Fabio Sgarbossa 《Packaging Technology and Science》2016,29(1):25-43
The fresh food industry is increasingly more interested in developing efficient and innovative solutions to guarantee quality and distribution sustainability; one of the main factors that influences such crucial aspects is packaging. This paper aims to perform a critical analysis of two existing packaging solutions, i.e. corrugated fibreboard boxes and re‐usable plastic containers, from both the economic and the environmental perspective, to highlight the main weaknesses. It then proposes two alternative packaging solutions. The analysis features different economic assessments and models with different environmental impacts, taking into account the characteristics of packaging solutions predominantly within two supply chain types: the traditional food supply chain and the short food supply chain. The economic and environmental models are applied to understand the limitations of existing packaging solutions, to develop two alternative solutions and finally to perform an overall analysis of all fresh food containers, allowing the definition of the most suitable container for each of the proposed supply chain scenarios, from both an economic and environmental perspective. The innovative aspect of the research lies in the simultaneous evaluation of economic and environmental factors and the introduction of two new packaging solutions, making it of interest to researchers and fresh food industry professionals alike. 相似文献
67.
Maria K. Kobanenko Daria S. Tretiakova Ekaterina S. Shchegravina Nadezhda V. Antipova Ivan A. Boldyrev Alexey Yu. Fedorov Elena L. Vodovozova Natalia R. Onishchenko 《International journal of molecular sciences》2022,23(3)
To assess the stability and efficiency of liposomes carrying a phospholipase A2-sensitive phospholipid-allocolchicinoid conjugate (aC-PC) in the bilayer, egg phosphatidylcholine and 1-palmitoyl-2-oleoylphosphatidylglycerol-based formulations were tested in plasma protein binding, tubulin polymerization inhibition, and cytotoxicity assays. Liposomes L-aC-PC10 containing 10 mol. % aC-PC in the bilayer bound less plasma proteins and were more stable in 50% plasma within 4 h incubation, according to calcein release and FRET-based assays. Liposomes with 25 mol. % of the prodrug (L-aC-PC25) were characterized by higher storage stability judged by their hydrodynamic radius evolution yet enhanced deposition of blood plasma opsonins on their surface according to SDS-PAGE and immunoblotting. Notably, inhibition of tubulin polymerization was found to require that the prodrug should be hydrolyzed to the parent allocolchicinoid. The L-aC-PC10 and L-aC-PC25 formulations demonstrated similar tubulin polymerization inhibition and cytotoxic activities. The L-aC-PC10 formulation should be beneficial for applications requiring liposome accumulation at tumor or inflammation sites. 相似文献
68.
Daria M. Sedlovets Maxim A. Knyazev Oleg V. Trofimov Sergei V. Koveshnikov 《Fullerenes, Nanotubes and Carbon Nanostructures》2020,28(4):309-312
ABSRTACTWe have previously found that pyrolysis of ethanol vapor on charge pre-patterned SiO2/Si substrate leads to controllable deposition of graphene-like films (GLFs). In this work we aim at the GLFs synthesis from acetone and isopropanol on SiO2/Si exposed to an electron beam with various energies and doses. Electron beam induced charge in 200?nm SiO2 is determined by the shift of the capacitance-voltage characteristics. Synthesized GLFs are characterized using Raman spectroscopy and atomic force microscopy. It is shown that the thickness of GLF on SiO2/Si increase together with the preliminary exposure dose and inversely associated with electron energies. 相似文献
69.
Daria Brambilla Cesare Mancuso Mariagrazia Rita Scuderi Paolo Bosco Giuseppina Cantarella Laurence Lempereur Giulia Di Benedetto Salvatore Pezzino Renato Bernardini 《Nutrition journal》2008,7(1):29
This review will discuss some issues related to the risk/benefit profile of the use of dietary antioxidants. Thus, recent
progress regarding the potential benefit of dietary antioxidants in the treatment of chronic diseases with a special focus
on immune system and neurodegenerative disorders will be discussed here. It is well established that reactive oxygen species
(ROS) play an important role in the etiology of numerous diseases, such as atherosclerosis, diabetes and cancer. Among the
physiological defense system of the cell, the relevance of antioxidant molecules, such as glutathione and vitamins is quite
well established. Recently, the interest of researchers has, for example, been conveyed on antioxidant enzyme systems, such
as the heme oxygenase/biliverdin reductase system, which appears modulated by dietary antioxidant molecules, including polyphenols
and beta-carotene. These systems possibly counteract oxidative damage very efficiently and finally modulate the activity of
oxidative phenomena occurring, for instance, during pathophysiological processes. Although evidence shows that antioxidant
treatment results in cytoprotection, the potential clinical benefit deriving from both nutritional and supplemental antioxidants
is still under wide debate. In this line, the inappropriate assumption of some lipophylic vitamins has been associated with
increased incidence of cancer rather than with beneficial effects. 相似文献
70.
Multiplex Analysis of Serum Cytokine Profiles in Systemic Lupus Erythematosus and Multiple Sclerosis
Mark M. Melamud Evgeny A. Ermakov Anastasiia S. Boiko Daria A. Kamaeva Alexey E. Sizikov Svetlana A. Ivanova Natalia M. Baulina Olga O. Favorova Georgy A. Nevinsky Valentina N. Buneva 《International journal of molecular sciences》2022,23(22)
Changes in cytokine profiles and cytokine networks are known to be a hallmark of autoimmune diseases, including systemic lupus erythematosus (SLE) and multiple sclerosis (MS). However, cytokine profiles research studies are usually based on the analysis of a small number of cytokines and give conflicting results. In this work, we analyzed cytokine profiles of 41 analytes in patients with SLE and MS compared with healthy donors using multiplex immunoassay. The SLE group included treated patients, while the MS patients were drug-free. Levels of 11 cytokines, IL-1b, IL-1RA, IL-6, IL-9, IL-10, IL-15, MCP-1/CCL2, Fractalkine/CX3CL1, MIP-1a/CCL3, MIP-1b/CCL4, and TNFa, were increased, but sCD40L, PDGF-AA, and MDC/CCL22 levels were decreased in SLE patients. Thus, changes in the cytokine profile in SLE have been associated with the dysregulation of interleukins, TNF superfamily members, and chemokines. In the case of MS, levels of 10 cytokines, sCD40L, CCL2, CCL3, CCL22, PDGF-AA, PDGF-AB/BB, EGF, IL-8, TGF-a, and VEGF, decreased significantly compared to the control group. Therefore, cytokine network dysregulation in MS is characterized by abnormal levels of growth factors and chemokines. Cross-disorder analysis of cytokine levels in MS and SLE showed significant differences between 22 cytokines. Protein interaction network analysis showed that all significantly altered cytokines in both SLE and MS are functionally interconnected. Thus, MS and SLE may be associated with impaired functional relationships in the cytokine network. A cytokine correlation networks analysis revealed changes in correlation clusters in SLE and MS. These data expand the understanding of abnormal regulatory interactions in cytokine profiles associated with autoimmune diseases. 相似文献