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   98篇
  免费   7篇
电工技术   2篇
化学工业   17篇
机械仪表   1篇
建筑科学   5篇
能源动力   3篇
轻工业   28篇
水利工程   4篇
无线电   4篇
一般工业技术   16篇
冶金工业   12篇
自动化技术   13篇
  2023年   3篇
  2022年   9篇
  2021年   9篇
  2020年   6篇
  2019年   2篇
  2018年   6篇
  2017年   11篇
  2016年   3篇
  2015年   2篇
  2014年   4篇
  2013年   8篇
  2012年   1篇
  2011年   5篇
  2010年   3篇
  2009年   2篇
  2008年   5篇
  2007年   2篇
  2006年   1篇
  2004年   3篇
  2002年   2篇
  2001年   1篇
  2000年   1篇
  1999年   3篇
  1998年   2篇
  1997年   5篇
  1996年   1篇
  1990年   1篇
  1989年   1篇
  1988年   1篇
  1986年   1篇
  1983年   1篇
排序方式: 共有105条查询结果,搜索用时 31 毫秒
61.
Microsystem Technologies - The analysis of hybrid PV/diesel/storage energy system in southern island of the province of South Leyte, Philippines is presented in this paper. Appropriate selection of...  相似文献   
62.
Development of stimuli-responsive supramolecular micelles that enable high levels of well-controlled drug release in cancer cells remains a grand challenge. Here, we encapsulated the antitumor drug doxorubicin (DOX) and pro-photosensitizer 5-aminolevulinic acid (5-ALA) within adenine-functionalized supramolecular micelles (A-PPG), in order to achieve effective drug delivery combined with photo-chemotherapy. The resulting DOX/5-ALA-loaded micelles exhibited excellent light and pH-responsive behavior in aqueous solution and high drug-entrapment stability in serum-rich media. A short duration (1–2 min) of laser irradiation with visible light induced the dissociation of the DOX/5-ALA complexes within the micelles, which disrupted micellular stability and resulted in rapid, immediate release of the physically entrapped drug from the micelles. In addition, in vitro assays of cellular reactive oxygen species generation and cellular internalization confirmed the drug-loaded micelles exhibited significantly enhanced cellular uptake after visible light irradiation, and that the light-triggered disassembly of micellar structures rapidly increased the production of reactive oxygen species within the cells. Importantly, flow cytometric analysis demonstrated that laser irradiation of cancer cells incubated with DOX/5-ALA-loaded A-PPG micelles effectively induced apoptotic cell death via endocytosis. Thus, this newly developed supramolecular system may offer a potential route towards improving the efficacy of synergistic chemotherapeutic approaches for cancer.  相似文献   
63.
Microsystem Technologies - Selecting a cost effective magnetic encoder is an important step in electrical machines motor drive system design. Resolvers and high-resolution encoders provide...  相似文献   
64.
Food Science and Biotechnology - Response of culturable microbes on the surface of apples treated with slightly alkaline electrolyzed water (SAIEW) is largely unexplored. Thus, the aim of this...  相似文献   
65.
This study was conducted to determine the occurrence and levels of total aflatoxins in complementary foods (CFs) and their ingredients. A total of 126 samples collected from 20 Districts from Amhara, Tigray, Oromia, and Southern Nations Nationalities and Peoples (SNNP) regions were analysed for levels of total aflatoxins using enzyme linked immunosorbent assay (ELISA). Aflatoxins were detected in 62 out of 66 pre-milling samples with mean range of 0.3–9.9 µg/kg. Aflatoxins were also detected in 19 out of 20 post-production CFs and in all of the one-month stored CFs at households and grain banks, with a mean range of 0.5–8.0, 3.6–11.3, and 0.2–12.4 µg/kg, respectively. Overall, 3 out of 126 samples exceeded the maximum limit (10 µg/kg). Although most aflatoxin levels were below the maximum limit and thus considered to be safe for consumption, more effort should be implemented to reduce contamination, as these CFs are intended for consumption by young children.  相似文献   
66.
Three hundred twenty honey samples were collected from Ethiopia, and categorized into nine monofloral honeys using melissopalynology. Theses monofloral honeys were investigated for their sugar profile, physicochemical properties, and quality of honeys. Sugars (fructose, glucose, sucrose, maltose, turanose, and isomaltose) were identified using high-performance liquid chromatography and physicochemical properties (moisture, water activity, pH, acidity, ash, minerals, conductivity, colour) using the Harmonized Method of the International Honey Commission. Moisture and water activity showed a strong regression coefficient (r2 = 0.92). Moisture content alone did not sufficiently describe the quality of honey during storage and processing.  相似文献   
67.
Oxidized fullerite was obtained by heating a fullerite sample intercalated with oxygen, (O2)0.44C60, up to 300 degrees C. Orientational phase transitions in the oxidized fullerite are studied using differential scanning calorimetry (DSC) and have been found to possess a specific enthalpy whose value is lower by 25% than in the initial (O2)0.44C60 sample. In order to find possible reasons for hindrance to the buckyball rotations, we performed optimizations of defect buckyball fullerenes C60-n with different distributions of vacancies along with the dimers C60-n-C60-n and C60-C60-n for n = 1-4 using density functional theory with generalized gradient approximation. We found that the dimerization energy ranges from 1.07 eV (C58-C58) to 6.56 eV (C56-C56) and from 1.81 eV (C60-C58) to 4.29 eV (C60-C56), respectively. The formation of such dimers, which could in addition interact with defect buckyball cages and form larger aggregates, is to be related to the lowering of the orientational transition enthalpy.  相似文献   
68.
BACKGROUND: Regional variations in stromal-epithelial interactions, mediated through soluble growth factors, may be responsible for differences in epithelial growth and death observed between regions of the rat prostatic ductal system. Since transforming growth factor-beta 1 (TGF-beta 1) can induce prostatic epithelial cell death in vitro and in vivo, we examined the localization and production of TGF-beta 1 with respect to the functional regions of the rat prostatic ductal system. METHODS: The distribution of TGF-beta 1 in the rat ventral prostate was examined by immunohistochemistry. Cell type-specific expression of TGF-beta 1 was determined using RT-PCR analysis of prostate epithelial and stromal cell fractions separated by Percoll gradient centrifugation. RESULTS: Immunohistochemical staining of normal prostate revealed regional variations in stromal TGF-beta 1 protein, which was most abundant in the stroma surrounding the degenerative proximal ducts. TGF-beta 1 staining was also tightly associated with the prostatic smooth muscle. Results of RT-PCR experiments confirmed the major source of TGF-beta 1 mRNA in normal rat prostate to be the stroma, with lesser expression by the epithelium. CONCLUSIONS: Stromal TGF-beta 1 was associated with cell death in the adjacent epithelial cell compartment in the prostatic ductal system, and alpha-smooth muscle actin-positive stromal cells may play a negative growth-regulatory role in the rat ventral prostate through production of TGF-beta 1.  相似文献   
69.
Gas permeability coefficient of cover concrete as a performance control   总被引:1,自引:1,他引:0  
A simple and practical gas permeability measurement method, known as the overpressure method, was used to assess the quality of cover concrete. This method enables distinguishing the quality of cover concrete both qualitatively and quantitatively, under laboratory conditions and/orin situ. The gas permeability values obtained are sensitive to changes in curing duration, water/cement ratio, age of testing and moisture history of the concrete. It has been confirmed from the test results that compressive strength alone cannot be a good indicator of concrete durability. It has also been observed that sorptivity and gas permeability values are linearly proportional to each other.
Résumé Une méthode simple et pratique pour mesurer la perméabilité au gaz, appelée la méthode de surpression, a été utilisée pour déterminer la qualité de l'épaisseur d'enrobage du béton. La méthode permet une détermination qualitative et quantitative, en laboratoire et/ouin situ. Les valuers de la perméabilité au gaz obtenues sont sensibles aux variations de la durée de cure, du rapport eau/ciment, de l'age de l'essai et de l'historique de l'humidité du béton. Les résultats des essais confirment que la résistance à la compression seule ne peut être un bon indicateur de la durabilité du béton. Il a également été constaté que les valeurs d'absorption et de perméabilité au gaz présentent une corrélation linéaire.


Editorial note Prof. Dr.-Ing. H.-W. Reinhardt is a RILEM Senior Member and works at FMPA Baden-Württemberg, a RILEM Titular Member. He is Chaiman of TC 146-TCF on Tightness of Concrete with respect to Fluids and is active in TC 148-SSC on Test methods for the Strain Softening response of Concrete. He is a corresponding member of TCs 107-CSP (Creep and Shrinkage Prediction models), 126-IPT (In-Place Testing of hardened concrete), 160-MLN (Methodology for Life prediction of concrete structures in Nuclear power plants) and 162-TDF (Test and Design methods for steel Fibre reinforced concrete). He is also a member of the Editorial Group of 090-FMA (Fracture Mechanics of concrete-Applicatons). Prof. Dr.-Ing. Reinhardt is a member of the Board of Editors ofMaterials and Structures and the RILEM National Delegate for Germany. Dr.-Ing. Abebe Dinku is now working at Addis Ababa University, Ethiopia, and is a Senior Member of RILEM.  相似文献   
70.
1. Two experiments were conducted on control (intact) and colostomised 4 to 7 week old broilers to evaluate the influence of 24 degrees C, diurnally cycling 24 to 35 degrees C and chronic 35 degrees C ambient temperatures on broiler mineral balance, urinary and faecal mineral excretion and urinary osmolar characteristics. 2. In the first experiment, colostomy had no significant effect on mineral balance. However, broilers exposed to high cycling ambient temperature reduced their retention of phosphorus, potassium, sodium, magnesium, sulphur, manganese, copper and zinc compared with birds housed at 24 degrees C. 3. Despite the minimal effect of high ambient temperature on urine production, minerals excreted disproportionately excreted in urine included potassium, magnesium, phosphorus and sulphur while copper and magnesium were lost primarily via the faeces. 4. In the second experiment, exposure to 35 degrees C increased urine output from 50.7 ml/12 h per kg of body weight at 24 degrees C to 101.3 ml/12 h per kg of body weight and was associated with an increased urine:water ratio and reduced urine osmolality. 5. Reduced urinary chloride and higher potassium, phosphorus, sulphur, sodium, magnesium, calcium and manganese excretion was observed for broilers housed in under high ambient temperatures compared to 24 degrees C. 6. These studies suggest that high ambient temperatures adversely influence mineral metabolism and, furthermore, that the route of excretion varies with the specific mineral and the environmental temperature exposure.  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