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   112篇
  免费   9篇
工业技术   121篇
  2022年   4篇
  2021年   11篇
  2020年   3篇
  2019年   8篇
  2018年   5篇
  2017年   6篇
  2016年   3篇
  2015年   3篇
  2014年   8篇
  2013年   15篇
  2012年   9篇
  2011年   9篇
  2010年   1篇
  2009年   4篇
  2008年   6篇
  2007年   3篇
  2006年   1篇
  2005年   2篇
  1999年   2篇
  1998年   6篇
  1997年   3篇
  1993年   1篇
  1990年   1篇
  1985年   2篇
  1983年   1篇
  1975年   1篇
  1973年   1篇
  1971年   1篇
  1969年   1篇
排序方式: 共有121条查询结果,搜索用时 0 毫秒
1.
A model of the pathways controlling the size of the human pupil is presented. Computer simulation of this model demonstrates the role played by each of the elements in the pupil pathways. Simulations of the effects of drugs and a few common abnormalities in the system also help to illustrate the workings of the internal processes. Computer models of this type can be used as teaching aids or as tools for testing of hypotheses regarding the system.  相似文献   
2.
A low‐cost and easy‐to‐fabricate microchip remains a key challenge for the development of true point‐of‐care (POC) diagnostics. Cellulose paper and plastic are thin, light, flexible, and abundant raw materials, which make them excellent substrates for mass production of POC devices. Herein, a hybrid paper–plastic microchip (PPMC) is developed, which can be used for both single and multiplexed detection of different targets, providing flexibility in the design and fabrication of the microchip. The developed PPMC with printed electronics is evaluated for sensitive and reliable detection of a broad range of targets, such as liver and colon cancer protein biomarkers, intact Zika virus, and human papillomavirus nucleic acid amplicons. The presented approach allows a highly specific detection of the tested targets with detection limits as low as 102 ng mL?1 for protein biomarkers, 103 particle per milliliter for virus particles, and 102 copies per microliter for a target nucleic acid. This approach can potentially be considered for the development of inexpensive and stable POC microchip diagnostics and is suitable for the detection of a wide range of microbial infections and cancer biomarkers.  相似文献   
3.
Almonds are blanched by exposure to hot water or steam-injected water to remove the pellicle (skin) from the kernel. This study evaluated the survival of Salmonella Enteritidis PT 30, Salmonella Senftenberg 775W and Enterococcus faecalis on whole raw almond kernels exposed to hot water. Whole, inoculated (7 to 9 log CFU/g) Nonpareil almonds (40 g) were submerged in 25 L of water maintained at 60, 70, 80 and 88 °C. Almonds were heated for up to 12 min, drained for 2 s, and transferred to 80 mL of cold (4 °C) tryptic soy broth. Almonds in broth were stomached at high speed for 2 min, serially diluted, plated onto tryptic soy and bismuth sulfite agars (Salmonella) or bile esculin agar (Enterococcus) and incubated at 37 °C for 24 and 48 h, respectively. D values of 2.6, 1.2, 0.75 and 0.39 min were calculated for exposure of S. Enteritidis PT 30 to water at 60, 70, 80 and 88 °C, respectively; the calculated z value was 35 C°. D values determined for Salmonella Senftenberg 775W and E. faecalis at 88 °C were 0.37 and 0.36 min, respectively. Neither Salmonella serovar could be recovered by enrichment of 1-g samples after almonds inoculated at 5 log CFU/g were heated at 88 °C for 2 min. These data will be useful to validate almond industry blanching processes.  相似文献   
4.
Dynamically vulcanized thermoplastic elastomer (TPE) nanocomposites based on polypropylene (PP), ethylene‐propylene diene monomer (EPDM) and cloisite 15A were prepared via direct melt mixing in a co‐rotating twin‐screw extruder. The mixing process was carried out with optimized processing parameters (barrel temperature = 180°C; screw speed = 150 rpm; and feeding rate = 0.2 kg/hr). The formulation used to prepare the nanocomposites was fixed to 75/20/5 (PP/EPDM/Cloisite©15A), expressed in mass fraction. Effect of mixing sequence on the properties of vulcanized and unvulcanized (TPE) nanocomposites prepared under similar conditions was investigated using X‐ray diffraction (XRD) and a tensile testing machine. Results showed that the sequence of mixing does affect the properties of final TPE nanocomposites. Accordingly, nanocomposite samples prepared through mixing the preblended PP/clay masterbatch with EPDM phase, show better clay dispersion within the polymer matrix. J. VINYL ADDIT. TECHNOL., 22:320–325, 2016. © 2014 Society of Plastics Engineers  相似文献   
5.
采用全俄石油钻进研究院提出的岩屑组分研究方法,分析了乌克兰顿巴斯矿区地质钻探过程中上返岩屑的组分研究结果,可为钻探冲洗液的选择提供理论依据。  相似文献   
6.
Postpartum depression (PPD) is a prevalent mood disorder estimated to affect 20%–40% of women worldwide after childbirth. In recent studies, the effect of vitamin D on prevention of mood disorders and depression has been investigated, but it is still unclear how vitamin D may affect PPD. The evidence on the relevance between vitamin D deficiency and PPD is inconsistent, and assessment of the recent literature has not previously been carried out. Moreover, there are few clinical studies on PPD and vitamin D supplementation. Five studies have so far assessed the relationship between the levels of vitamin D and PPD. Findings from cohort studies suggest that vitamin-D deficiency is related to the incidence of PPD and vitamin D may play a significant role in the recovery of women with PPD, but it is uncertain whether these actions are the effect of vitamin D on the function of hypothalamic-pituitary-adrenal (HPA) axis, the levels of estradiol, serotonin, pro-inflammatory cytokines, and/or of other mechanisms involved in PPD.  相似文献   
7.
Chlorosulfonic acid immobilized on CuFe2O4 nanoparticles (nano-CuFe2O4@SO3H) was evaluated as a recoverable catalyst for the one-pot cyclo-dehydration of dimedone and synthesis of chromeno[4,3-b]chromene derivatives by reaction of arylaldehydes, dimedone or 1,3-cyclohexanedione, with 3-hydroxycoumarine or 4-hydroxycoumarine in good to excellent yield. Also, 2,2′-Arylmethylene bis(3-hydroxy-5,5-dimethyl-2-cyclohexene-1-one) was synthesized by the reaction of aromatic aldehyde and dimedone using nano-CuFe2O4 in ethanol at room temperature. The catalyst could be recycled several times without significant loss of its catalytic activity. Clean methodologies, easy work-up procedure, high yield and simple preparation of the catalyst are some advantages of this procedure.  相似文献   
8.
In today's digital era no one has knowledge, access or control of all their available personal information. This makes the very concepts of privacy and consent increasingly illusory and raises questions that are likely to shape not only the future form of cyberspace, but also the political, social and economic interactions within it. The institutions tasked with regulation of the physical world are ill equipped to respond and undertake a similar role in the virtual world; the timescales, dimensions and scope are all materially different. This article sets out five dilemmas that will need to be addressed in the search for solutions.  相似文献   
9.
The present study proposes new conditions for achieving the aged-look effect of denim. Indigo dyed cotton fabrics were treated by corona discharge at different power levels and number of passages. Colorimetric parameters of corona treatment were assessed by the CIE L*a*b* colorimetric system and the pH and colour fastness of samples were tested. The surfaces of dyed samples were studied by scanning electron microscopy and Fourier Transform–infrared/attenuated total reflectance (FTIR/ATR) analysis. Under the same conditions of corona treatment, the faded-look effect was reduced as the depth of dyeing was increased. Increasing the power and the number of passages increases L* and b * and decreases a * values. This indicates that samples become lighter and yellower but soaping can reduce yellowness. FTIR/ATR results show that indigo dye oxidises, and isatin and anthranilic acid are produced. The pH levels of corona-treated samples reduce as the power and number of passages increase. This acidification is in agreement with the results of FTIR/ATR analysis.  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