首页 | 官方网站   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   420篇
  免费   27篇
  国内免费   8篇
工业技术   455篇
  2023年   6篇
  2022年   13篇
  2021年   27篇
  2020年   17篇
  2019年   23篇
  2018年   26篇
  2017年   20篇
  2016年   35篇
  2015年   16篇
  2014年   19篇
  2013年   29篇
  2012年   25篇
  2011年   33篇
  2010年   14篇
  2009年   12篇
  2008年   12篇
  2007年   14篇
  2006年   7篇
  2005年   8篇
  2004年   6篇
  2003年   10篇
  2002年   5篇
  2001年   6篇
  2000年   1篇
  1999年   6篇
  1998年   6篇
  1997年   8篇
  1996年   12篇
  1995年   5篇
  1994年   2篇
  1993年   7篇
  1992年   2篇
  1990年   1篇
  1989年   1篇
  1988年   1篇
  1986年   2篇
  1985年   3篇
  1984年   1篇
  1983年   3篇
  1982年   2篇
  1979年   1篇
  1978年   1篇
  1976年   3篇
  1975年   2篇
  1973年   2篇
排序方式: 共有455条查询结果,搜索用时 218 毫秒
1.
A presence of mycotoxins in feed is one of the most alarming issues in the poultry feed industry. Ochratoxins, produced by several Aspergillus and Penicillium species, are important mycotoxin regarding the health status of poultry birds. Ochratoxins are further classified into to several subtypes (A, B, C, etc) depending on their chemical structures, but ochratoxin A (OTA) is considered the most important and toxic. Bentonite clay, belonging to phyllosilicates and formed from weathering of volcanic ashes, has adsorbent ability for several mycotoxins. The present study was designed to study the effects of bentonite clay upon OTA-induced immunosuppression in broiler chicks. For this, 480 day-old broiler chicks were procured from a local hatchery and then different combinations of OTA (0.15, 0.3, or 1.0 mg/kg) and bentonite clay (5, 10, and 20 g/kg) were incorporated into their feed. At 13, 30, and 42 days of age, parameters such as antibody responses to sheep red blood cells, in situ lymphoproliferative responses to mitogen (PHA-P), and in situ phagocytic activity (i.e., via carbon clearance) were determined respectively. The results indicated there was a significant reduction of total antibody and immunoglobulin titres, lymphoproliferative responses, and phagocytic potential in OTA-treated birds, suggesting clear immunosuppression by OTA in birds in a dose-dependent manner. These results were also significantly lower in all combination groups (OTA with bentonite clay), suggesting few to no effects of feeding bentonite clay upon OTA- induced alterations in different immune parameters.  相似文献   
2.
Flue gas emissions and the harmful effects of these gases urge to separate and capture these unwanted gases. Ionic liquids due to negligible vapor pressure, thermal stability, and wide electrochemical stability have expanded its application in gas separations. A comprehensive overview of the recent developments and applications of ionic liquid membranes (ILMs) for gas separation is given. The three general classifications of ILMs, such as supported ionic liquid membranes (SILMs), ionic liquid polymeric membranes (ILPMs), and ionic liquid mixed‐matrix membranes (ILMMMs) along with their applications, for the separation of various mixed gases systems is discussed in detail. Furthermore, issues, challenges, computational study, and future perspectives for ILMs are also considered.  相似文献   
3.
Dehydrins (DHNs) play an important role in abiotic stress tolerance in a large number of plants, but very little is known about the function of DHNs in pepper plants. Here, we isolated a Y1SK2-type DHN gene “CaDHN3” from pepper. To authenticate the function of CaDHN3 in salt and drought stresses, it was overexpressed in Arabidopsis and silenced in pepper through virus-induced gene silencing (VIGS). Sub-cellular localization showed that CaDHN3 was located in the nucleus and cell membrane. It was found that CaDHN3-overexpressed (OE) in Arabidopsis plants showed salt and drought tolerance phenotypic characteristics, i.e., increased the initial rooting length and germination rate, enhanced chlorophyll content, lowered the relative electrolyte leakage (REL) and malondialdehyde (MDA) content than the wild-type (WT) plants. Moreover, a substantial increase in the activities of antioxidant enzymes; including the superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), ascorbate peroxidase (APX), and lower hydrogen peroxide (H2O2) contents and higher O2•− contents in the transgenic Arabidopsis plants. Silencing of CaDHN3 in pepper decreased the salt- and drought-stress tolerance, through a higher REL and MDA content, and there was more accumulation of reactive oxygen species (ROS) in the CaDHN3-silenced pepper plants than the control plants. Based on the yeast two-hybrid (Y2H) screening and Bimolecular Fluorescence Complementation (BiFC) results, we found that CaDHN3 interacts with CaHIRD11 protein in the plasma membrane. Correspondingly, the expressions of four osmotic-related genes were significantly up-regulated in the CaDHN3-overexpressed lines. In brief, our results manifested that CaDHN3 may play an important role in regulating the relative osmotic stress responses in plants through the ROS signaling pathway. The results of this study will provide a basis for further analyses of the function of DHN genes in pepper.  相似文献   
4.
Clean Technologies and Environmental Policy - The present study was focused on the optimized biodiesel production using Moringa oleifera (M. oleifera) and rice bran oils, characterization, and...  相似文献   
5.
6.
7.
Illite is a group of clay minerals that are expected to be widely used in catalyst fabrication, radioactive element adsorption, and so forth, due to its excellent adsorption properties. However, the shape control limitation of the illite product should be overcome to maximize its utilization and properties. We herein propose additive manufacturing (AM) as one of the best solutions to solve this structural drawback. Digital light processing (DLP) technology with the film-type of the material supplying system was adapted instead of the general vat-type DLP system to increase illite printability. The photo-curability and printability of illite-contained photocurable suspension were optimized. The color effect due to different ferric oxide content in yellow- and white-illite which influence the photopolymerization process also adjusted thoroughly. White illite showed better photo-curability and could be increased solid loading than yellow illite. The defect-free illite products with three-dimensional complex structures, which cannot be produced by typical ceramic processes, were obtained by DLP technology for both yellow- and white-illite after sintering at 1100°C. The overcoming of shape control limitation of illites by ceramic AM proved in this study has excellent potential for expanding illite utilities in various applications.  相似文献   
8.
The research was carried out to develop geopolymers mortars and concrete from fly ash and bottom ash and compare the characteristics deriving from either of these products. The mortars were produced by mixing the ashes with sodium silicate and sodium hydroxide as activator solution. After curing and drying, the bulk density, apparent density and porosity, of geopolymer samples were evaluated. The microstructure, phase composition and thermal behavior of geopolymer samples were characterized by scanning electron microscopy, XRD and TGA-DTA analysis respectively. FTIR analysis revealed higher degree of reaction in bottom ash based geopolymer. Mechanical characterization shows, geopolymer processed from fly ash having a compressive strength 61.4 MPa and Young's modulus of 2.9 GPa, whereas bottom ash geopolymer shows a compressive strength up to 55.2 MPa and Young's modulus of 2.8 GPa. The mechanical characterization depicts that bottom ash geopolymers are almost equally viable as fly ash geopolymer. Thermal conductivity analysis reveals that fly ash geopolymer shows lower thermal conductivity of 0.58 W/mK compared to bottom ash geopolymer 0.85 W/mK.  相似文献   
9.
In this study,alumina/A380 composite coatings were fabricated by cold spray.The influence of alumina particulates' morphology(spherical and irregular) and content on the deposition behavior of the coatings(including surface roughness,surface residual stress,cross-sectional microstructure and microhardness) was investigated.Results revealed that the spherical alumina mainly shows micro-tamping effect during deposition,which result in remarkable low surface roughness and porosity of the coatings.In addition,very low deposition efficiency and good interfacial bonding between the coating and the substrate were achieved.For irregular alumina particles,the embedding of ceramic particulates in the coating was dominant during deposition process,resulting in high retention in the final deposit.However,it showed limited influence on porosity,surface roughness and interfacial bonding of the deposit.The coatings containing irregular alumina particulates exhibited much higher microhardness than those containing spherical alumina due to the higher load-bearing capacity of deposited alumina.  相似文献   
10.
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-23

京公网安备 11010802026262号