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   241篇
  免费   3篇
  国内免费   6篇
工业技术   250篇
  2024年   1篇
  2023年   2篇
  2022年   3篇
  2021年   10篇
  2020年   9篇
  2019年   1篇
  2018年   2篇
  2017年   20篇
  2016年   10篇
  2015年   13篇
  2014年   22篇
  2013年   17篇
  2012年   13篇
  2011年   10篇
  2010年   20篇
  2009年   27篇
  2008年   14篇
  2007年   12篇
  2006年   11篇
  2005年   7篇
  2004年   4篇
  2003年   4篇
  2002年   5篇
  2001年   4篇
  2000年   1篇
  1999年   1篇
  1998年   3篇
  1997年   1篇
  1996年   2篇
  1990年   1篇
排序方式: 共有250条查询结果,搜索用时 46 毫秒
1.
Traceability is the ability to follow a product along its lifecycle. It ensures product safety and quality along the supply chain, managing information generated by several players. Even though regulations establish the information that has to be traced, each player generates much more product (and process) information, which could be used to add value to products, with respect to, not only traceability, but also the lifecycle approach. However, the concepts do not appear to be immediately related in scientific panorama. This paper aims to explore the relationship between traceability and lifecycle through a systematic literature review. Six industries (Software, Manufacturing, Automotive, Automation, Aircraft, and Aerospace) and seven subject areas (Software engineering; System engineering; Industry 4.0; New product development; Process management; Data Management; and Environmental sustainability) were identified through bibliometric analysis. To better explore this relationship in the context of the food industry, a content analysis on lead papers’ sample was performed to identify traceability and lifecycle definitions, methodologies and technologies and their relation. The results of the work, synthetised in a proposed research map, will be of interest to those who are approaching the subject for the first time, and for companies involved in product lifecycle management and food traceability.  相似文献   
2.
3.
摘 要:目的 对湿米粉与淀粉制品(统称为“湿粉”)及其原料米中分离的椰毒假单胞菌酵米面亚种进行溯源分析。方法 采用GB/T 4789.29—2003在14份湿粉及其原料米中分离出34株唐菖蒲伯克霍尔德氏 菌并进行菌株全基因组重测序,以Burkholderia_gladioli_Co14作为参比基因,基于单核苷酸多态性(SNP)数据构建进化树,分析不同菌株的同源关系。结果 来源于相同产地标识的样品的菌株呈现较好聚类;来源于同一生产企业的湿粉和碎米样品的菌株具有高度同源关系。结论 提示原料米中椰毒假单胞菌酵米面亚种的基因组序列与产地溯源具有较大的相关性,在湿粉生产加工过程中存在椰毒假单胞菌酵米面亚种污染传递的风险。  相似文献   
4.
To explore the behavioural and cognition patterns of fighter pilots under visual and verbal alert conditions, 20 right-handed subjects participated in the experiment after 200 h of flight task training, and ERP technology was used to conduct EEG experiments under four conditions: high time pressure visual alert, low time pressure visual alert, fast speech speed verbal alert, and slow speech speed verbal alert. The results indicated the following: 1) the highest accuracy rate and shortest reaction time could be achieved under the slow speech speed verbal alert condition, indicating that the slow speech speed alert performance was optimal. 2) Subjects in the verbal alert trial showed a “right hemisphere advantage”, and the brain function area was located in the right temporal lobes. The speech speed correlated negatively with the latency and amplitude of P80.3) Subjects in the visual alert trial showed a “left hemisphere advantage”, and the brain activity was located in the left parietal lobes. 4) The latency of P80 evoked by verbal alert was earlier than that of N140 evoked by visual alert, indicating that a verbal alert causes an earlier attention effect in pilots. Based on the eye movement experiment, the performance of visual and verbal dual-channel alert was significantly higher than that of visual alert.  相似文献   
5.
The present study aimed to identify the potential existence of spatio-temporal variability in the fatty acid (FA) profile of the adductor muscle (AM) of a commercially important bivalve, the common cockle Cerastoderma edule, and determine if such variability can be used to trace their geographic origin post-harvesting. Common cockles were sampled in eight ecosystems along the coast of mainland Portugal, as well as in two different channels within one of those ecosystems over two consecutive years. Results showed significant differences in FA profiles among ecosystems, namely due to different levels of eicosapentaenoic acid (EPA; 20:5n-3), arachidonic acid (20:4n-6), ratio of polyunsaturated FA (PUFA) n-3/n-6, monounsaturated FA (MUFA; 18:1n-9 and 20:1n-9/11) and bacterial FA (15:0, 17:0 and 18:1n-7). FA profiles also displayed significant differences between two consecutive years in channels from the same ecosystem. Overall, while the FA profile displayed by the AM of C. edule can be successfully used to trace their geographic origin, the existence of temporal variability requires a periodical verification of FA signatures to identify potential shifts, namely when comparing specimens from the same ecosystem.  相似文献   
6.
Doppler velocimetry is widely used in the measurement of nanometre resonance vibrations of micro-electromechanical systems (MEMS). It has excellent sensitivity and precision, but typical engineering applications do not require traceability of these velocity measurements to the SI system. While Doppler velocimetry is, in principle, easy to make traceable to the velocity of light, in practice a frequency-to-voltage conversion in common commercial instruments breaks this traceability unless calibrated. Typically, though, calibration is performed at a much lower frequency than those typical of MEMS devices, without the guarantee that the calibration is applicable in this higher frequency regime.

We present a method of traceable measurement of velocity in terms of the velocity of light, valid for the range of frequency and nanometre amplitudes typical of MEMS devices driven to resonance vibration. This is achieved by analysis of sideband amplitudes in the interference spectrum before demodulation of the Doppler signal. These sideband amplitudes can conveniently be measured using a benchtop spectrum analyser, a piece of widely available electrical test equipment. We illustrate the method with measurements on individual AFM cantilevers. In combination with cantilever calibration methods based on MEMS devices this method enables traceable calibration of those cantilevers employed for the measurement of pico- and nanonewton forces between individual biomolecules.  相似文献   
7.
The aim of the study was to conduct an extensive survey on Listeria monocytogenes and Listeria spp. environmental contamination in 13 cheese-making plants. A total of 409 environmental and food samples were collected during years 2011–2013. Listeria spp. contamination was observed in all the facilities, while L. monocytogenes was recovered from 12 facilities with a prevalence ranging between 3.0% and 22.6%. Floor drains were the most contaminated sampling sites (48.8% of positive samples), serving as harbourage site for subsequent contamination. Out of 616 isolates, 277 (45.0%) were Listeria innocua, 274 (44.5%) L. monocytogenes, 41 (6.6%) Listeria ivanovii, 14 (2.3%) Listeria welshimeri and 10 (1.6%) Listeria gravyi. Serotyping carried out by PCR and agglutination method for L. monocytogenes revealed that 169 strains (61.7%) were serotype 1/2a, 65 (23.7%) 4b, 20 (7.3%) 1/2b, 10 (3.6%) 3a, 7 (2.5%) 1/2c and 3 (1.1%) 3b. PFGE conducted on L. monocytogenes isolates using AscI and ApaI restriction enzymes, yielded 6 clusters. Two predominant PFGE clusters were observed including respectively 36 and 32 strains. Within cheese-making plants, L. monocytogenes showed wide variability with strains distributed up to 4 different clusters. Pulsotypes isolated from raw milk filter were never detected in the processing environment, indicating that the contamination originated from sources other than raw milk. The isolation of strains with similar profile from different sampling sites, within and among cheese-making plants, indicated the possible transfer of L. monocytogenes contamination along production lines and from one facility to another. Strains recovered from food were confirmed as originating from the processing environment.  相似文献   
8.
Assignment tests based on multilocus genotypes are becoming increasingly important to certify the origin of livestock products and assure food safety and authenticity. The potential of microsatellites for determining the origin of beef products among cattle breeds present in the Portuguese market with the Protected Denomination of Origin (PDO) was studied. Methodologies were used to establish the number of populations under study and to allocate individuals to their original population. The STRUCTURE program was used to perform the strictly Bayesian method and the GENECLASS 2 program was used to accomplish two types of assignment tests. The STRUCTURE program converged to 9 populations, precisely the number of populations under study. Regarding the individual allocation, the strictly Bayesian method implemented by the STRUCTURE program allowed 96% of correct allocations when running the program without the knowledge of the source populations and 98% when the STRUCTURE program was run knowing the source populations of the animals. In the assignment test performed by the GENECLASS 2, 95% and 97% of individuals were correctly allocated by the frequency and the Bayesian methods, respectively. These results show the potential feasibility for traceability scheme based on microsatellites.  相似文献   
9.
10.
Huge resources are invested in metrology and standards in the natural sciences, engineering, and across a wide range of commercial technologies. Significant positive returns of human, social, environmental, and economic value on these investments have been sustained for decades. Proven methods for calibrating test and survey instruments in linear units are readily available, as are data- and theory-based methods for equating those instruments to a shared unit. Using these methods, metrological traceability is obtained in a variety of commercially available elementary and secondary English and Spanish language reading education programs in the U.S., Canada, Mexico, and Australia. Given established historical patterns, widespread routine reproduction of predicted text-based and instructional effects expressed in a common language and shared frame of reference may lead to significant developments in theory and practice. Opportunities for systematic implementations of teacher-driven lean thinking and continuous quality improvement methods may be of particular interest and value.  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-23

京公网安备 11010802026262号