首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   161篇
  免费   2篇
化学工业   50篇
金属工艺   1篇
机械仪表   7篇
建筑科学   2篇
能源动力   4篇
轻工业   25篇
水利工程   5篇
无线电   16篇
一般工业技术   28篇
冶金工业   7篇
自动化技术   18篇
  2024年   2篇
  2023年   8篇
  2022年   18篇
  2021年   26篇
  2020年   7篇
  2019年   12篇
  2018年   11篇
  2017年   9篇
  2016年   13篇
  2015年   4篇
  2014年   1篇
  2013年   7篇
  2012年   9篇
  2011年   10篇
  2010年   3篇
  2009年   7篇
  2008年   4篇
  2007年   2篇
  2006年   1篇
  2002年   1篇
  1998年   2篇
  1997年   1篇
  1996年   2篇
  1995年   2篇
  1994年   1篇
排序方式: 共有163条查询结果,搜索用时 15 毫秒
61.
The neuroprotective and antioxidative effects of germinated brown rice (GBR), brown rice (BR) and commercially available γ-aminobutyric acid (GABA) against cell death induced by hydrogen peroxide (H(2)O(2)) in human neuroblastoma SH-SY5Y cells have been investigated. Results show that GBR suppressed H(2)O(2)-mediated cytotoxicity and induced G0/G1 phase cell cycle arrest in SH-SY5Y cells. Moreover, GBR reduced mitochondrial membrane potential (MMP) and prevented phosphatidylserine (PS) translocation in SH-SY5Y cells, key features of apoptosis, and subsequent cell death. GBR exhibited better neuroprotective and antioxidative activities as compared to BR and GABA. These results indicate that GBR possesses high antioxidative activities and suppressed cell death in SH-SY5Y cells by blocking the cell cycle re-entry and apoptotic mechanisms. Therefore, GBR could be developed as a value added functional food to prevent neurodegenerative diseases caused by oxidative stress and apoptosis.  相似文献   
62.
    
Heavy metal pollution of water is a global concern, which adversely affects human health because of its resistance to biodegradation and thus its transmission in the food chain via bioaccumulation. Nano zerovalent iron (nZVI) is very effective for the removal of heavy metals and is cost effective in terms of production. However, the main problems of nZVI are agglomeration and ease of oxidation. Several stabilization materials have been implemented to limit the aggregation of nZVI, such as silica, activated carbon and biochar. In comparison, as a support material, biochar possesses a large surface area, high stability and strong adsorption capacity, as well as being obtainable from various types of materials. Thus, this work aims to establish the opportunities available on the use of biochar-supported nZVI in utilizing its ability to stabilize and immobilize the nZVI. This review also reports the preparation, modification and surface enhancement of biochar, nZVI and biochar-nZVI for practical use as adsorbents. This review shows that modifications of the nZVI surface can help in their stabilization and reduction of aggregation. Additionally, this review is able to increase one's understanding of heavy metal sorption behavior by biochar-supported nZVI as it is the important as heavy metal sorption is driven based on biochar-nZVI type and heavy metal species which involve numerous mechanisms, including physical binding, complexation, ion exchange, surface precipitation and electrostatic interactions. Furthermore, this research reviews the adsorption parameters, including the crucial adsorption mechanism of heavy metals onto biochar-nZVI; the reusability of the biochar-nZVI is also discussed in this work. © 2022 Society of Chemical Industry (SCI).  相似文献   
63.
Self-assembled GaAs nanowires have been grown on Si by molecular beam epitaxy without the use of any outside metal catalyst. The growth occurs on Si facets obtained by the cleavage of Si(100) substrates. The growth has been obtained with or without Ga pre-deposition. In both cases two kinds of nanowires have been obtained. The wires of the first type clearly present a Ga droplet at their free end and have a lattice structure that is wurtzite for wide regions beneath the Ga droplet. The second type, in contrast, ends with pyramidally shaped GaAs and has a crystal lattice that is mainly zincblende with only a few and small wurtzite regions, if any. The Ga-ended nanowires are longer than the others and thinner on average. The experimental findings suggest that the two types of nanowires grow after different growth processes.  相似文献   
64.
The surface of the inner race of a detachable roller bearing is monitored periodically to determine the deterioration pattern under normal conditions together with the vibration level. The surface of the inner race is scanned using an infinite focus microscope to evaluate surface properties utilizing the 2D and 3D parameters. Both parameters successfully assess the surface degradation and wear of the bearing surface. Using the Dowson-Higginson equation on elastohydrodynamic lubrication, the theoretical lubrication film was calculated and the lubrication regimes identified. A high vibration level can be associated with surface roughness properties and relative lubrication regime. This work highlights the relationship between the bearing vibration level and the bearing inner race surface parameters. The two surface parameters with the highest Pearson correlation coefficient with the vibration level are the areal surface roughness Sa (0.997) and the average roughness Ra (0.936).  相似文献   
65.
66.
67.
Two different monoclonal antibodies (MAb) were raised against 2,4-dichlorophenol hydroxylase (DCP-hydroxylase) of Ralstonia eutropha JMP134 (pJP4), the second enzyme in the 2,4-D-degradative pathway of this bacterium. The utility of these antibodies in detecting and characterizing 2,4-D-degrading soil bacteria was investigated. One MAb (F6) reacted with DCP-hydroxylase from 27 out of 36 strains tested, while the other (MAb C3) reacted with only 17 isolates. When used with the colony blot technique, MAb F6 was useful for detecting cross-reacting strains on plates of pure cultures or of mixtures containing nondegraders even when 2,4-D degraders were outnumbered 60 to 1. 2,4-D-degrading strains could also be detected from plates spread with enrichment cultures but not from primary isolation plates spread from soil dilutions, presumably because the ratio of degraders to nondegraders was too low. Colonies of some strains that were very distantly related genetically, but produced functionally similar DCP-hydroxlase enzymes, were detected by MAb F6. This result suggests that MAbs could be useful for detecting functionally similar proteins expressed from tfdB analogs, even in the absence of detectable DNA homology between the genes encoding them.  相似文献   
68.
Several epitopes in the human melanoma antigens recognized by HLA-A2-restricted CTLs have a relatively low MHC-binding affinity and as a result may be expressed at very low densities on the cell surface, indicating that these epitopes may not be efficient immunogens. To express these epitopes at higher densities on the surface of antigen-presenting cells and therefore improve their immunogenicity, a DNA construct in which a cDNA fragment encoding the melanoma epitope MART-1(27-35) or gp100(280-288) was inserted between sequences encoding the leader and the HLA-A*0201 protein. Cells transfected with these epitope-HLA fusion constructs were recognized by HLA-A2-restricted melanoma-reactive CTLs specific for the MART-1 or gp100 epitope. In addition, tumor-reactive CTLs could be induced from PBMCs of patients with metastatic melanoma by in vitro stimulation with HMY-C1R B-cell lines expressing the MART-1 or gp100 epitope-HLA-A*0201 fusion protein. These epitope-HLA fusion constructs may be useful for the development of immunotherapies for patients with melanoma.  相似文献   
69.
    
There is a huge potential for recycling animal manure in agricultural farms, but fecal microorganisms from land-applied animal manure can join shallow groundwater through leaching especially in alluvial formations. Thus, this study investigated the leaching rate of total viable count (TVC) below a 1.1-m soil depth in a field lysimeter planted with rice–maize–rice rotation, where the rotation received different treatments, i.e., chemical fertilizer, dry manure, fresh manure, alternate wetting and drying (AWD) irrigation, and traditional irrigation. Leachate samples of six major irrigation/rainfall events were collected and analyzed for TVC concentration. In the Aman rice season, manure application had a significantly higher TVC leaching (5.5 × 106 colony forming units (CFU) per milliliter) than the no-manure treatment (8.2 × 104 CFU/mL). In the maize season, manure application increased more than one log-scale of TVC leaching concentration. A higher concentration of TVC leaching (3 × 105 CFU/mL) was observed even after 93 d of fresh manure application. The fresh manure had a higher TVC load, and it possibly helped microorganisms survive longer by providing a more manure-like environment in the soil. In the Boro rice season, manure application increased the TVC leaching up to 3–4 log-scale compared with the control treatment. The AWD irrigation increased TVC leaching compared with the continuous irrigation because the desiccation fractures developed in the AWD irrigation helped TVC bypass the organic-rich topsoil. The Boro rice fields had higher TVC leaching than the maize fields with higher manure doses. The study suggests that there is scope to improve manure management to protect the groundwater quality.  相似文献   
70.
    
Transmission line is a vital part of the power system that connects two major points, the generation, and the distribution. For an efficient design, stable control, and steady operation of the power system, adequate knowledge of the transmission line parameters resistance, inductance, capacitance, and conductance is of great importance. These parameters are essential for transmission network expansion planning in which a new parallel line is needed to be installed due to increased load demand or the overhead line is replaced with an underground cable. This paper presents a method to optimally estimate the parameters using the input-output quantities i.e., voltages, currents, and power factor of the transmission line. The equivalent π-network model is used and the terminal data i.e., sending-end and receiving-end quantities are assumed as available measured data. The parameter estimation problem is converted to an optimization problem by formulating an error-minimizing objective function. An improved particle swarm optimization (PSO) in terms of time-varying control parameters and chaos-based initialization is used to optimally estimate the line parameters. Two cases are considered for parameter estimation, the first case is when the line conductance is neglected and in the second case, the conductance is considered into account. The results obtained by the improved algorithm are compared with the standard version of the algorithm, firefly algorithm and artificial bee colony algorithm for 30 number of trials. It is concluded that the improved algorithm is tremendously sufficient in estimating the line parameters in both cases validated by low error values and statistical analysis, comparatively.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号