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   5285篇
  免费   381篇
  国内免费   50篇
电工技术   4篇
综合类   231篇
化学工业   1367篇
金属工艺   36篇
机械仪表   34篇
建筑科学   35篇
矿业工程   24篇
能源动力   9篇
轻工业   3670篇
水利工程   1篇
石油天然气   14篇
无线电   31篇
一般工业技术   182篇
冶金工业   46篇
原子能技术   7篇
自动化技术   25篇
  2024年   39篇
  2023年   90篇
  2022年   133篇
  2021年   205篇
  2020年   188篇
  2019年   192篇
  2018年   166篇
  2017年   178篇
  2016年   143篇
  2015年   162篇
  2014年   247篇
  2013年   264篇
  2012年   361篇
  2011年   429篇
  2010年   248篇
  2009年   203篇
  2008年   191篇
  2007年   336篇
  2006年   349篇
  2005年   302篇
  2004年   243篇
  2003年   194篇
  2002年   140篇
  2001年   129篇
  2000年   130篇
  1999年   96篇
  1998年   98篇
  1997年   71篇
  1996年   50篇
  1995年   40篇
  1994年   30篇
  1993年   31篇
  1992年   9篇
  1991年   7篇
  1990年   6篇
  1989年   2篇
  1988年   4篇
  1987年   1篇
  1986年   2篇
  1985年   3篇
  1984年   1篇
  1980年   3篇
排序方式: 共有5716条查询结果,搜索用时 18 毫秒
11.
紫草色素原植物系紫草科Broaginaceae几种植物的根,又称紫根色素。该研究首次用人工栽培的硬紫草(Lithospermum erythrohizon Sieb.)的根,作了加工工艺和特性的研究。产品得率近1%,色价E 1^1Q5nm达150以,卫生指标符合有关规定,是种理想的脂溶性红色素。  相似文献   
12.
着色型珠光颜料涂布纸的研制   总被引:1,自引:1,他引:0  
本文论述了着色型珠光颜料涂布纸的研制工作,并对影响珠光涂料制备的几个因素进行探讨.优化结果表明,瓷土0~30%,珠光颜料70%~100%,胶粘剂25%~30%,固含量23%~25%,涂布量10~15g/m2时,其纸面呈现强烈的珠光光泽,适用于胶印.  相似文献   
13.
介绍了苯乙烯-马来酸酐(SMA)共聚物的合成方法和分散性能。探讨了它对颜料分散的机理、影响分散性能的主要因素,以及在喷墨印花中的应用前景作了展望。  相似文献   
14.
新疆茶藨中紫红色素的萃取工艺及稳定性研究   总被引:4,自引:1,他引:3  
本文介绍了新疆野生植物茶子果实中,紫红色素提取及定性检验和色素的提取工艺。  相似文献   
15.
Properties of Edible Films from Total Milk Protein   总被引:5,自引:0,他引:5  
The mechanical properties and water vapor permeability of edible films made from various total milk proteins (TMPs) were investigated. Two TMPs obtained from nonfat dry milk (NDM) by removing lactose and three TMPs obtained from a commercial source were studied. Lactose was extracted from NDM by ultrafiltration or suspension in ethanol followed by filtration. TMP concentrate obtained by ultrafiltration (UF) produced films with the lowest water vapor permeability (WVP) and the highest tensile strength at break. Commercial TMP concentrates produced films more ductile than those from the UF-TMP or retentate from ethanol extraction. Further research is needed to improve mechanical properties of UF-TMP films without increasing the WVP.  相似文献   
16.
叶子花红色素提取工艺的优化   总被引:3,自引:0,他引:3  
马银海  李维莉  彭永芳   《食品科学》2003,24(1):78-80
本文研究了用树脂吸附和分离叶子花红色素,比较了4种树脂对叶子花红色素的吸附,在叶子花红色素提取过程中用AB-8树脂吸附,洗脱剂用40%的乙醇,洗脱效果好,且AB-8树脂使用20次后吸附性能仍稳定。  相似文献   
17.
Samples of chicken meat from spent laying hens were obtained by four different methods: (1) manual deboning of whole carcasses; (2) manual deboning of skinned carcasses; (3) mechanical deboning of whole carcasses; and (4) mechanical deboning of skinned carcasses. The meat was packaged, frozen and stored at ?18 °C for up to 3 months. Functional properties studied were pH, emulsifying capacity (EC) and water‐holding capacity (WHC) and, in addition, pigment concentration was investigated. Sensory properties included aroma, colour, texture and overall acceptability, as judged by a trained panel using a nine‐point hedonic scale. Removal of the skin prior to deboning by either method gave significantly higher values (P < 0.05) for EC, while WHC values were not significantly different among the experimental treatments, despite higher pH values for mechanically‐deboned meat, with and without skin. Pigment concentrations were highest in meat from Treatment 4 and lowest for Treatment 1, but values for both methods of deboning were affected by the presence of skin. There were no significant differences between treatments for any of the sensory properties studied. Changes occurring in the meat during frozen storage are described.  相似文献   
18.
The mechanism of colour change during the pigment dispersion process and during powder application to the skin surface was studied by examining the colour extension properties of Yellow. Red , and Black iron oxides in white powder bases. A new measure for the evaluation of the degree of colour extension was devised. This measure corresponded well with human visual sensation, and was found to be useful for comparing the rates of colour extension of pigments. The rate of colour extension of pigments was found to vary in the order: Yellow acicular Red granular Red Black. This result explains colour darkening and the change towards reddish tones during the pigment dispersion process, because Yellow extends fully in the early stage of the process but Red , especially in granular form, and Black continue to extend even in the later stage. Acicular Red iron oxide is more favourably employed than the granular form to attain sufficient colour extension of foundations with lower energy expenditure, and to decrease the discrepancy between the cake colour and the colour of applied powder.
Le développement des oxydes de fer et effet sur les nuances des fonds de teint compacts  相似文献   
19.
Disruption of retinal pigment epithelial (RPE barrier integrity is a hallmark feature of various retinal blinding diseases, including diabetic macular edema and age-related macular degeneration, but the underlying causes and pathophysiology are not completely well-defined. One of the most conserved phenomena in biology is the progressive decline in mitochondrial function with aging leading to cytopathic hypoxia, where cells are unable to use oxygen for energy production. Therefore, this study aimed to thoroughly investigate the role of cytopathic hypoxia in compromising the barrier functionality of RPE cells. We used Electric Cell-Substrate Impedance Sensing (ECIS) system to monitor precisely in real time the barrier integrity of RPE cell line (ARPE-19) after treatment with various concentrations of cytopathic hypoxia-inducing agent, Cobalt(II) chloride (CoCl2). We further investigated how the resistance across ARPE-19 cells changes across three separate parameters: Rb (the electrical resistance between ARPE-19 cells), α (the resistance between the ARPE-19 and its substrate), and Cm (the capacitance of the ARPE-19 cell membrane). The viability of the ARPE-19 cells and mitochondrial bioenergetics were quantified with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay and seahorse technology, respectively. ECIS measurement showed that CoCl2 reduced the total impedance of ARPE-19 cells in a dose dependent manner across all tested frequencies. Specifically, the ECIS program’s modelling demonstrated that CoCl2 affected Rb as it begins to drastically decrease earlier than α or Cm, although ARPE-19 cells’ viability was not compromised. Using seahorse technology, all three concentrations of CoCl2 significantly impaired basal, maximal, and ATP-linked respirations of ARPE-19 cells but did not affect proton leak and non-mitochondrial bioenergetic. Concordantly, the expression of a major paracellular tight junction protein (ZO-1) was reduced significantly with CoCl2-treatment in a dose-dependent manner. Our data demonstrate that the ARPE-19 cells have distinct dielectric properties in response to cytopathic hypoxia in which disruption of barrier integrity between ARPE-19 cells precedes any changes in cells’ viability, cell-substrate contacts, and cell membrane permeability. Such differences can be used in screening of selective agents that improve the assembly of RPE tight junction without compromising other RPE barrier parameters.  相似文献   
20.
装袋是食用菌代替料生产过程中的一个重要环节。针对工作强度大、安全性低的现状,研发了一种新型气动工艺装袋机。实践结果表明:该设备能较好满足当前食用菌代料生产中装袋操作要求,且具有结构简单、生产率高、成本低、安全性好的特征。  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