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   278篇
  免费   11篇
  国内免费   1篇
电工技术   2篇
化学工业   71篇
金属工艺   5篇
机械仪表   9篇
建筑科学   10篇
矿业工程   1篇
能源动力   19篇
轻工业   70篇
石油天然气   3篇
无线电   7篇
一般工业技术   50篇
冶金工业   13篇
原子能技术   2篇
自动化技术   28篇
  2024年   3篇
  2023年   2篇
  2022年   6篇
  2021年   17篇
  2020年   12篇
  2019年   12篇
  2018年   9篇
  2017年   13篇
  2016年   15篇
  2015年   6篇
  2014年   15篇
  2013年   29篇
  2012年   16篇
  2011年   26篇
  2010年   15篇
  2009年   17篇
  2008年   12篇
  2007年   18篇
  2006年   9篇
  2005年   5篇
  2004年   9篇
  2003年   5篇
  2002年   5篇
  2001年   1篇
  1998年   2篇
  1997年   1篇
  1996年   4篇
  1994年   2篇
  1992年   1篇
  1986年   1篇
  1981年   1篇
  1978年   1篇
排序方式: 共有290条查询结果,搜索用时 15 毫秒
101.
Gluten-free products exhibit some undesirable features due to the absence of the gluten network. Effects of ingredient interactions and baking type on the food matrix have not clearly been explored. The objective of this study was to investigate the effect of ingredient and baking types on the quality characteristics of cake by using nuclear magnetic resonance (NMR) relaxometry. Carob bean flour containing gluten-free cakes formulated either with hydroxypropyl methylcellulose (HPMC) or whey protein were baked in both conventional and microwave–infrared combination ovens. Specific gravity of batters was measured and cakes were analyzed in terms of weight loss, hardness, and specific volume. Microstructure of cakes was investigated by scanning electron microscopy (SEM). NMR relaxometry was used to support the information about water retention, and water–food matrix interactions. Cakes baked in microwave–infrared (MW-IR) combination oven had some undesirable characteristics due to higher weight loss and insufficient gelatinization of starch which was supported by SEM results. Compartments of relaxation data also indicated two specific proton pools for MW-IR-baked samples, which represented gelatinized and ungelatinized parts of the cakes. Spin–spin relaxation times (T2) were found to be good indicators for explaining the physical state and distribution of water inside the samples, having Pearson correlation of 0.96, 0.86, and ??0.98 (p?<?0.05) between monoexponential T2 values and hardness, specific volume, and moisture, respectively.  相似文献   
102.
Characterizing water and fat distributions in fried foods is of major importance in terms of taste and nutrition. The objective of this study was to introduce a new technique to quantify water and fat distributions of chicken nuggets coated with methylcellulose (MC) through the use of magnetic resonance imaging (MRI) and NMR relaxometry. Multi-slice-multi-echo (MSME-Spin Echo based) images were performed on a 1.03 T spectrometer for the whole chicken nuggets to obtain relaxation time distribution of different regions (core and crust) of the nugget. MSME images provided the relaxation spectra of the core and crust separately and showed that relaxation times and relative areas of the proton pools in crust and core regions are correlated (mostly, R2 > 0.85) with moisture and fat content. Results demonstrated that MSME images in combination with T2 relaxometry are appropriate tools to quantify spatial water and fat distribution in various food products.  相似文献   
103.
Congenital dyserythropoietic anemias (CDA) are a rare group of red-blood-cell disorders of unknown etiology that are characterized by ineffective erythropoiesis, pathognomonic cytopathology of the nucleated red blood cells in the bone marrow, and secondary hemochromatosis. In CDA type I, bone-marrow electron microscopy reveals characteristic findings in erythroid precursors, including spongy heterochromatin and enlarged nuclear pores. Since the genetic basis of CDA type I is not evident, we used homozygosity and linkage mapping to localize the genetic defect responsible for CDA type I in 25 Bedouins from four large consanguineous families. We report the linkage of this disease to markers on chromosome 15 located at q15. 1-q15.3. Fourteen markers within a 12-cM interval were typed in the relevant family members. Nine of the markers yielded maximum LOD scores of 1.625-12.928 at a recombination fraction of .00. Linkage disequilibrium was found only with marker D15S779. Haplotype analysis revealed eight different carrier haplotypes and highlighted the existence of a founder haplotype. Identification of historical crossover events further narrowed the gene location to between D15S779 and D15S778. The data suggest localization of the CDA type I gene within a 0.5-cM interval. The founder mutation probably occurred >/= 400 years ago. Sequence analysis of the coding region of protein 4.2, the only known erythroid-specific gene in the locus, did not reveal any change in the CDA type I patients. Future analysis of this locus may lead to the identification of a gene essential to normal erythropoiesis.  相似文献   
104.
With the use of the general beam formulation, the modulus of the complex degree of coherence for partially coherent cosh-Gaussian, cos-Gaussian, Gaussian, annular and higher-order Gaussian optical beams is evaluated in atmospheric turbulence. For different propagation lengths in horizontal atmospheric links, the moduli of the complex degree of coherence at the source and receiver planes are examined when reference points are taken on the receiver axis and off-axis. In the on-axis case, it is observed that in propagation, the moduli of the complex degree of coherence are symmetrical and look like the intensity profile of the related coherent beam propagating in a turbulent atmosphere. For all the beams considered, the moduli of the complex degree of coherence profiles turn into Gaussian shapes beyond certain propagation lengths. In the off-axis case, the moduli of complex degree of coherence patterns become drifted at the earlier propagation lengths. Among the beams investigated, the cos-Gaussian beam is found to be almost independent of the changes in the source partial coherence parameter, and the annular beam seems to be affected the most against the variations of the source partial coherence parameter.  相似文献   
105.
In the present study, the performance of electrocoagulation process with aluminum electrodes in the treatment of Cu(2+), Zn(2+) and Mn(2+) containing aqueous solutions was investigated by depending on type of anion in solution, considering some operating conditions such as initial metal concentration and pH. Results obtained from synthetic wastewater showed that type of anion in solutions has a significant effect on the metal removal. The initial concentration of zinc influenced significantly the performance of electrocoagulation process as compared with the results obtained from Mn and Cu metals. Anions studied did not generate an important difference between pH variations. Best removals for three metals were achieved with increasing the pH in the presence of both anions. Total removals of copper and zinc reached almost 100% after 5 min at pH values > 7. At the end of the experiments for 35 min, the Mn removals were 85 and 80% in the presence of sulfate and chloride anions, respectively.  相似文献   
106.
This study aimed to produce new multi-featured epoxy composites that are advanced in terms of mechanical properties, wear and impact resistance, and glass transition and heat deflection temperatures. Epoxy composites filled with chemically surface-treated poly (tetrafluoroethylene) (PTFE) powders at various ratios were prepared to obtain these improved properties. The chemical treatment was carried out via a Na-naphthalenide system. After this treatment, the x-ray photoelectron spectroscopy results presented the existence of functional groups such as OH, carbonyl groups, and CC unsaturation points on the surface of the PTFE powders. On the PTFE surfaces, while the atomic ratios of carbon and oxygen were substantially increased, the fluorine ratio presented a significant decrease after the chemical treatment. However, the wear rates of the novel composites were highly advanced despite this large decrease in the fluorine ratio on the surface of the PTFE powders. Moreover, functional groups such as OH, carbonyl groups, and CC unsaturation points and spongelike or network structures on the PTFE surfaces provided the opportunity to obtain strong adhesion and interfacial bonding between the surface-modified PTFE powders and the matrix. Strength and modulus values showed substantial enhancement besides the IZOD impact resistance. All glass transition and heat deflection temperatures were also substantially improved.  相似文献   
107.
108.
Suspended buildings typically have a core as the primary and suspended floors as the secondary structures. These configurations offer visual transparency, smaller vertical components, and seismic attenuation via the primary–secondary structure interaction. Such attenuation is further enhanced by the modularization of the suspended segment which allows large drifts but prevents them from causing damage. Previously conducted shake‐table tests have confirmed these features. However, how the component performance contributes to system performance has not been quantitated. To address this gap, fragility analyses are conducted for 10‐story experimentally validated models with optimized supplemental dampers and inter‐module stiffness. Multiple limit state functions are proposed to provide a full account of damage sources. Additionally, a mapping rule from the component‐level to the system‐level limit states is developed which captures the influence of damage distribution on system‐level limit states. Results for the uncontrolled suspended building indicate that for the PGV of 0.5 m/s, the failure probabilities of the repairable and life safety limit states are 97% and 83%, respectively. These probabilities are 92% and 27% for the frame structure with viscous dampers, 58% and 5% for the passive‐controlled modularized suspended building system (MSBS), and 45% and 3% for MSBS with optimal vertical distributions of modularized secondary structure.  相似文献   
109.
Poly l ‐lactic acid grafted starch (St‐g‐PLA) copolymers were directly synthesized under microwave irradiation by using sodium hydroxide (NaOH) and stannous 2‐ethyl hexanoate acting as a catalyst, without the use of toxic solvents. The product were characterized by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (13C CP/MAS NMR), X‐ray diffraction (XRD), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA‐DTG). SEM analysis indicated that microwave heating had a considerable effect on the interfacial adhesion between PLA and starch. Thermogravimetric analysis (TGA‐DTG) revealed that copolymers exhibited better thermal stability. Maximum PLA grafting was achieved with the following reaction conditions: 450W microwave power, monomer ratio of 1:5 and 0.4M of NaOH. This study demonstrates that it is possible to obtain St‐g‐PLA copolymers with better processing characteristics and smaller sizes via microwave‐assisted synthesis. The applied procedure is an interesting “green” synthesis method for the production of biodegradable materials used in a diverse range of applications. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42937.  相似文献   
110.
Down syndrome (DS) is one of the most common chromosomal disorders. The factors contributing to the mental retardation together with other defects in this syndrome have not been fully explained. Individuals with DS have extra rRNA gene family since they carry an extra chromosome 21. The few reports available are on the relationship between the nucleolus organizer regions (NORs) and DS phenotype. The in vivo regulation of NORs expression on the extra chromosome 21 is not completely understood. Previous studies have shown that nucleoli of lymphocytes from infants (mostly neonates) with DS contain more in vivo and in vitro nucleolar AgNOR proteins when compared with healthy infants. The objective of this study is to compare the in vivo nuclear AgNOR protein level in nucleoplasms (also called as karyoplasm) of nonstimulated peripheral blood lymphocytes from babies/children with DS and healthy controls. Peripheral blood samples obtained from 20 babies/children with DS and 20 matched healthy controls were smeared on clean glass slides and then AgNOR staining was performed. The AgNOR protein level in nucleoplasms of lymphocytes from both groups was calculated using a computer program. Nearly 100 interphase nuclei per individual were analysed. Average nuclear AgNOR protein levels in nucleoplasms of lymphocytes from babies/children with DS were found to be significantly higher than those of the controls (P < 0.001). On the basis of our present results, we propose that the increase of nuclear AgNOR protein in in vivo conditions may contribute to the formation of DS phenotypes. Microsc. Res. Tech. 79:133–139, 2016. © 2016 Wiley Periodicals, Inc.  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