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:从到   被引次数:从到   他引次数:从到 提示：输入*表示无穷大
全文获取类型
  收费全文   1107篇
  免费   12篇
  国内免费   3篇
专业分类
电工技术   3篇
化学工业   355篇
金属工艺   11篇
机械仪表   22篇
建筑科学   36篇
矿业工程   3篇
能源动力   24篇
轻工业   365篇
水利工程   10篇
石油天然气   10篇
无线电   57篇
一般工业技术   117篇
冶金工业   24篇
原子能技术   3篇
自动化技术   82篇
出版年
  2024年   21篇
  2023年   24篇
  2022年   82篇
  2021年   89篇
  2020年   33篇
  2019年   48篇
  2018年   40篇
  2017年   42篇
  2016年   45篇
  2015年   40篇
  2014年   50篇
  2013年   68篇
  2012年   82篇
  2011年   88篇
  2010年   53篇
  2009年   43篇
  2008年   57篇
  2007年   53篇
  2006年   35篇
  2005年   29篇
  2004年   22篇
  2003年   18篇
  2002年   9篇
  2001年   6篇
  2000年   5篇
  1999年   2篇
  1998年   6篇
  1997年   5篇
  1996年   3篇
  1995年   1篇
  1994年   6篇
  1993年   6篇
  1992年   1篇
  1991年   2篇
  1990年   2篇
  1987年   2篇
  1983年   2篇
  1980年   1篇
  1970年   1篇
排序方式： 共有1122条查询结果，搜索用时 0 毫秒
91.
    
The antimicrobial potential of alginate films (AFs) and alginate/chitosan composite films with two different mass proportions of the biopolymers, 82.5:17.5 (CF1) and 65:35 (CF2), containing potassium sorbate (KS) or natamycin was evaluated. At the practical limit of KS addition (0.17 g KS per gram of alginate) for pure AFs, no inhibition zones were observed against Debaromyces hansenii, Penicillium commune and Penicillium roqueforti by the agar diffusion test. Above this concentration, films became opaque, brittle and showed a whitish precipitate over their surface, making them not suitable for use. However, alginate and alginate/chitosan composite films containing natamycin were able to inhibit the growth of the three microorganisms listed above. Natamycin was effective at concentrations as low as 0.005 g per gram of biopolymer for AF and 0.01 g per gram of biopolymer for both composite films, alginate/chitosan 65:35 (CF1) and alginate/chitosan 82.5:17.5 (CF2) against all microorganisms tested. The inhibitory zone diameter increased as concentration of natamycin increased. Active films containing 0.04 g natamycin per gram of biopolymer obtained in the present study exhibited suitable functional attributes and showed excellent perspectives as active antimicrobial films intended for food protection applications. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   
92.
    
Antibiotics are potentially a cause of neurotoxicity in dialysis patients, the most common are the beta‐lactams as ceftazidime and cefepime, and few cases have been reported after piperacillin/tazobactam use. This report presents a case of a hypertensive and diabetic 67‐year‐old woman in regular hemodialysis, which previously had a stroke. She was hospitalized presenting pneumonia, which was initially treated with cefepime. Two days after treatment, she presented dysarthria, left hemiparesis, ataxia, and IX and X cranial nerves paresis. Computed tomography showed no acute lesions and cefepime neurotoxicity was hypothesized, and the antibiotic was replaced by piperacillin/tazobactam. The neurologic signs disappeared; however, 4 days after with piperacillin/tazobactam treatment, the neurological manifestations returned. A new computed tomography showed no new lesions, and the second antibiotic regimen withdrawn. After two hemodialysis sessions, the patient completely recovered from neurological manifestations. The patient presented sequentially neurotoxicity caused by two beta‐lactams antibiotics. This report meant to alert clinicians that these antibiotics have dangerous neurological effects in chronic kidney disease patients.  相似文献   
93.
    
Self‐propelled activated carbon‐based Janus particle micromotors that display efficient locomotion in environmental matrices and offer effective ‘on‐the‐fly’ removal of wide range of organic and inorganic pollutants are described. The new bubble‐propelled activated carbon Janus micromotors rely on the asymmetric deposition of a catalytic Pt patch on the surface of activated carbon microspheres. The rough surface of the activated carbon microsphere substrate results in a microporous Pt structure to provide a highly catalytic layer, which leads to an effective bubble evolution and propulsion at remarkable speeds of over 500 μm/s. Such coupling of the high adsorption capacity of carbon nanoadsorbents with the rapid movement of these catalytic Janus micromotors, along with the corresponding fluid dynamics and mixing, results in a highly efficient moving adsorption platform and a greatly accelerated water purification. The adsorption kinetics and adsorption isotherms have been investigated. The remarkable decontamination efficiency of self‐propelled activated carbon‐based Janus micromotors is illustrated towards the rapid removal of heavy metals, nitroaromatic explosives, organophosphorous nerve agents and azo‐dye compounds, indicating considerable promise for diverse environmental, defense, and public health applications.  相似文献   
94.
    
An extensive analysis of the front contact influence on concentrator GaAs solar cell performance has been carried out. The fill factor, open circuit voltage and efficiency have been calculated by varying the front contact specific resistance and the metal sheet resistance for 500X, 1000X and 2000X. An optimum front grid design has also been developed. The simulations have been carried out using a 3D model based on distributed circuit units, and by a classic lumped model, showing the need to use distributed models to achieve an accurate concentrator solar cell modeling as well as a precise front grid design.  相似文献   
95.
    
Thermal actuators are extensively used in microelectromechanical systems (MEMS). Heat transfer through and around these microstructures are very complex. Knowing and controlling them in order to improve the performance of the micro-actuator, is currently a great challenge. This paper deals with this topic and proposes a dynamic thermal modelling of thermal micro-actuators. Thermal problems may be modelled using electrical analogy. However, current equivalent electrical models (thermal networks) are generally obtained considering only heat transfers through the thickness of structures having considerable height and length in relation to width (walls). These models cannot be directly applied to micro-actuators. In fact, micro-actuator configurations are based on 3D beam structures, and heat transfers occur through and around length. New dynamic and static thermal networks are then proposed in this paper. The validities of both types of thermal networks have been studied. They are successfully validated by comparison with finite elements simulation and analytical calculations.  相似文献   
96.
The correlation between the ontogeny of Ubisch bodies and pollen development in Oxalis articulata was studied with Transmission Electron Microscopy (TEM). The ultrastructural changes observed during the different stages of development in the tapetal cells are related to Ubisch bodies, sporopollenin and pollen-kitt formation. The pro-orbicules have the appearance of lipid globuli and their formation is related to the endoplasmic reticulum of rough type (ERr). The lipid globules or pro-orbicules disappear in the mature Ubisch bodies, and the places that they occupied remain free of contents or with pollen-kitt.  相似文献   
97.
    
The inorganic content and the catalytic performance pose metal-loaded enzyme nanoflowers as promising candidates for developing bioelectrodes capable of functioning without the external addition of a redox mediator. However, these protein-inorganic hybrids have yet to be successfully applied in combination with electrode materials. Herein, the synthesis procedure of these bionanomaterials is reproposed to precisely control the morphology, composition, and performance of this particular protein-mineral hybrid, formed by glucose oxidase and cobalt phosphate. This approach aims to enhance the adherence and electron mobility between the enzyme and a carbon electrode. The strategy relies on dressing the protein in a tailored thin nanogel with multivalent chemical motifs. The functional groups of the polymer facilitate the fast protein sequence-independent biomineralization. Furthermore, the engineered enzymes enable the fabrication of robust cobalt-loaded enzyme inorganic hybrids with exceptional protein loads, exceeding 90% immobilization yields. Notably, these engineered biohybrids can be readily deposited onto flat electrode surfaces without requiring chemical pre-treatment. The resulting bioelectrodes are robust and exhibit electrochemical responses even without the addition of a redox mediator, suggesting that cobalt complexes promote electron wiring between the active site of the enzyme and the electrode.  相似文献   
98.
    
Therapeutic deep eutectic solvents (THEDES) are an emerging family of eutectic mixtures gaining increasing interest in the biomedical space. The immobilization of THEDES into polymer networks allows bioactive eutectogels to expand their application scope to topical drug delivery. Herein, this work presents the first set of elastomeric eutectogels constructed by supporting a therapeutic eutectic system with skin permeation ability in a protein scaffold dynamically crosslinked by a natural polyphenol. In this ionic eutectic, gelatin undergoes gelation through an unexpected mechanism in striking contrast with classical hydrogels, which is herein thoroughly studied. Interestingly, the polyphenol controls the conformation of the protein structure, enabling tuning up the mechanical and viscoelastic behavior of the dynamic eutectogel networks from elastic to hyperelastic. The resultant protein eutectogels exhibit strain-hardening behavior, thermoreversible gel-to-sol transition, and excellent adhesive performance. Furthermore, these versatile materials retain the bioactivity of the liquid THEDES and favor skin occlusion, assisting the delivery of both hydrophilic and hydrophobic substances in ex vivo porcine skin in a time-dependent penetration process. These ultrastretchable eutectogels show new interplays between protein scaffolds and eutectic mixtures, paving the way for innovative therapeutic soft materials.  相似文献   
99.
    
This work aimed to evaluate the impact of buffalo milk and nondairy ingredients on sensory properties and acceptability of custards intended for children. For this, a consumer study with 100 children aged 8 to 12 was performed. Three custard models were formulated using buffalo milk and variable amounts of corn starch, sucrose and colourant/flavouring. Compositional, mechanical and chromatic properties of custards were related to sensory characteristics and overall liking scores. Obtained results allowed understanding the consumers' preferences and identifying the drivers of liking. Buffalo milk constitutes a promising raw material for the formulation of custard intended for children.  相似文献   
100.
    
The coffee industry is one of the most important commercial value chains worldwide. Nonetheless, it is also associated to several social, economic, and environmental concerns that impair its sustainability. The present review is focused on these main sustainability concerns from the field to the coffee cup, as well as on the strategies that are being developed and/or implemented to attain sustainability and circular economy principles in the different chain segments. In this context, distinct approaches have been applied, such as sustainable certifications (e.g., voluntary sustainability standards), corporate sustainability initiatives, direct trade, relationship coffee concepts, geographical indication, legislations, waste management, and byproducts valorization, among others. These strategies are addressed and discussed throughout this review, as well as their recognized advantages and limitations. Overall, there is still a long way to go to attain the much-desired sustainability in the coffee chain, being essential to join the efforts of all actors and entities directly or indirectly involved, namely, producers, retailers, roasters, governments, educational institutions (such as universities and scientific research institutes), and organizations.  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