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   41篇
  免费   1篇
化学工业   12篇
建筑科学   1篇
能源动力   2篇
轻工业   7篇
水利工程   1篇
一般工业技术   15篇
冶金工业   4篇
  2023年   1篇
  2022年   1篇
  2021年   4篇
  2019年   1篇
  2017年   2篇
  2014年   1篇
  2013年   4篇
  2012年   2篇
  2011年   4篇
  2009年   8篇
  2008年   3篇
  2007年   3篇
  2006年   1篇
  2005年   1篇
  2002年   2篇
  1997年   1篇
  1993年   1篇
  1987年   1篇
  1976年   1篇
排序方式: 共有42条查询结果,搜索用时 46 毫秒
21.
Health disparities that affect whole communities may involve factors like housing quality that lie at least partly within planners' realm of policy influence. This article demonstrates a link between housing and childhood asthma. The magnitude of the childhood asthma epidemic in Harlem in New York City and the commitment of engaged community partners led to an interdisciplinary, participatory, and multifaceted approach to the planning, implementation, and evaluation of the Harlem Children's Zone Asthma Initiative. Here we present the first year's data on environmental triggers in the homes of program participants, showing that intensive, community-based programs can reduce both home environmental triggers and adverse childhood asthma outcomes. This provides an example of a community-wide public health intervention that informs public policy and planning, and may provide a sustainable model for reducing childhood asthma in impoverished communities.  相似文献   
22.
Biocatalytic surface coatings are prepared herein for localized synthesis of drugs and their on‐demand, site‐specific delivery to adhering cells. This novel approach is based on the incorporation of an enzyme into multilayered polymer coatings to accomplish enzyme‐prodrug therapy (EPT). The build‐up of enzyme‐containing multilayered coatings is characterized and correlations are drawn between the multilayer film assembly conditions and the enzymatic activity of the resulting coatings. Therapeutic effect elicited by the substrate mediated EPT (SMEPT) strategy is investigated using a prodrug for an anticancer agent, SN‐38. The performance of biocatalytic coatings under flow conditions is investigated and it is demonstrated that EPT allows synthesizing the drugs on‐demand, at the time desired and in a controllable amount to suit particular applications. Finally, using cells cultured in sequentially connected flow chambers, it is demonstrated that SMEPT affords a site‐specific drug delivery, that is, exerts a higher therapeutic effect in cells adhering directly to the biocatalytic coatings than in the cells cultured “downstream”. Taken together, these data illustrate biomedical opportunities made possible by engineering tools of EPT into multilayered polymer coatings and present a novel, highly versatile tool for surface mediated drug delivery.  相似文献   
23.
The impairment of skeletal muscle function is one of the most debilitating least understood co-morbidity that accompanies acromegaly (ACRO). Despite being one of the major determinants of these patients’ poor quality of life, there is limited evidence related to the underlying mechanisms and treatment options. Although growth hormone (GH) and insulin-like growth factor-1 (IGF-1) levels are associated, albeit not indisputable, with the presence and severity of ACRO myopathies the precise effects attributed to increased GH or IGF-1 levels are still unclear. Yet, cell lines and animal models can help us bridge these gaps. This review aims to describe the evidence regarding the role of GH and IGF-1 in muscle anabolism, from the basic to the clinical setting with special emphasis on ACRO. We also pinpoint future perspectives and research lines that should be considered for improving our knowledge in the field.  相似文献   
24.
The Brazilian pine-fruit shell (Araucaria angustifolia) is a food residue, which was used in natural and carbonized forms, as low-cost adsorbents for the removal of methylene blue (MB) from aqueous solutions. Chemical treatment of Brazilian pine-fruit shell (PW), with sulfuric acid produced a non-activated carbonaceous material (C-PW). Both PW and C-PW were tested as low-cost adsorbents for the removal of MB from aqueous effluents. It was observed that C-PW leaded to a remarkable increase in the specific surface area, average porous volume, and average porous diameter of the adsorbent when compared to PW. The effects of shaking time, adsorbent dosage and pH on adsorption capacity were studied. In basic pH region (pH 8.5) the adsorption of MB was favorable. The contact time required to obtain the equilibrium was 6 and 4h at 25 degrees C, using PW and C-PW as adsorbents, respectively. Based on error function values (F(error)) the kinetic data were better fitted to fractionary-order kinetic model when compared to pseudo-first order, pseudo-second order, and chemisorption kinetic models. The equilibrium data were fitted to Langmuir, Freundlich, Sips and Redlich-Peterson isotherm models. For MB dye the equilibrium data were better fitted to the Sips isotherm model using PW and C-PW as adsorbents.  相似文献   
25.
Ribeirão das Lajes Reservoir was constructed in 1905 for energy production, and is now used as a domestic water supply for about 1 million people. The reservoir was considered as being general monomictic, exhibiting water column mixing in the winter. Water column mixing, however, did not occur in the deepest parts of the reservoir in the warm year of 2005. Nevertheless, the long stratification period leads to an anoxic, nutrient-rich hypolimnion that exhibits poor water quality in the deepest part. The meteorological events of cold front passages in the reservoir region were not able to disrupt the water column stability, or affect its water quality for domestic supply. Maintenance of thermal stratification over most of the year was likely because of the low influence of wind, long water retention time, and the input of cold water from the tributary and from rain directly draining into the metalimnion.  相似文献   
26.
Monolithic capillary columns were prepared by transition metal-catalyzed ring-opening metathesis copolymerization of norborn-2-ene and 1,4,4a,5,8,8a-hexahydro-1,4,5,8-exo,endo-dimethanonaphthalene inside a silanized 200-microm-i.d. fused-silica capillary using a mixture of toluene and 2-propanol as porogen and Cl2(PCy3)2Ru(=CHPh) as initiator. The synthesized columns allowed the rapid and highly efficient separation of single- and double-stranded nucleic acids by ion-pair reversed-phase high-performance liquid chromatography and of proteins by reversed-phase high-performance liquid chromatography. Compared to 3-mm-i.d. analytical columns synthesized from an identical polymerization mixture, a considerable improvement in the peak widths at half-height of oligonucleotides in the order of 60-80% was obtained. Significant differences in morphology between the capillary column, where the surface of the monolith was rather soft and rugulose, and the analytical column, where the surface was very sharp and smooth, were observed, most probably due to differences in polymerization kinetics. The synthesized monoliths were successfully applied to the separation of the diastereomers of phosphorothioate oligodeoxynucleotides. To confirm the identity of the eluting compounds on the basis of their intact molecular masses, the chromatographic separation system was on-line hyphenated to electrospray ionization mass spectrometry.  相似文献   
27.
K-doped lithium silicates were synthesized as CO2 sorbents using rice husks as silica source. Two different doping methods were used to prepare the solids, incipient wetness impregnation and co-impregnation. Noticeable differences were observed between the sorbents obtained by each route. Unlike the co-impregnated sample, a KLi3SiO4 phase was detected by XRD in the doped-samples prepared by incipient wetness impregnation. This phase was associated with a porous layer deposition over the sorbent particle surface, which was observed by SEM. The effect of CO2 partial pressure and sorption temperature was evaluated for the solids. A remarkable improvement of the capture efficiency was observed in the doped-samples, especially at low temperature and CO2 partial pressure. The kinetics of the samples was studied using the double exponential model and operando Raman and DRIFT spectroscopies. Different reactivity properties were found depending on the synthesis method employed. The complete analysis of the results allowed us to propose a transformation mechanism for the solids during the sorption step, highlighting the improvement of surface reaction and volumetric diffusion processes in the CO2 capture step.  相似文献   
28.
The gas-phase oxidation of aqueous ethanol with dioxygen has been examined with a new nanoparticle V2O5/TiO2 catalyst. Product selectivity could to a large extent be controlled by small alterations of reaction parameters, allowing production of acetaldehyde at a selectivity higher than 90%, near quantitative conversion at 175–200 °C. Furthermore, a selectivity above 80% for acetic acid could be achieved at low gas hourly space velocity at temperatures as low as 165 °C.  相似文献   
29.
Multi-walled carbon nanotubes and powdered activated carbon were used as adsorbents for the successful removal of Reactive Red M-2BE textile dye from aqueous solutions. The adsorbents were characterised by infrared spectroscopy, N2 adsorption/desorption isotherms and scanning electron microscopy. The effects of pH, shaking time and temperature on adsorption capacity were studied. In the acidic pH region (pH 2.0), the adsorption of the dye was favourable using both adsorbents. The contact time to obtain equilibrium at 298 K was fixed at 1 h for both adsorbents. The activation energy of the adsorption process was evaluated from 298 to 323 K for both adsorbents. The Avrami fractional-order kinetic model provided the best fit to the experimental data compared with pseudo-first-order or pseudo-second-order kinetic adsorption models. For Reactive Red M-2BE dye, the equilibrium data were best fitted to the Liu isotherm model. Simulated dyehouse effluents were used to check the applicability of the proposed adsorbents for effluent treatment.  相似文献   
30.
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