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   79篇
  免费   7篇
工业技术   86篇
  2024年   1篇
  2022年   7篇
  2021年   5篇
  2020年   4篇
  2019年   3篇
  2018年   4篇
  2017年   2篇
  2016年   2篇
  2015年   2篇
  2014年   2篇
  2013年   4篇
  2012年   5篇
  2011年   1篇
  2010年   2篇
  2009年   3篇
  2008年   3篇
  2007年   3篇
  2006年   4篇
  2005年   4篇
  2004年   2篇
  2003年   1篇
  2001年   1篇
  2000年   3篇
  1998年   4篇
  1994年   1篇
  1989年   1篇
  1988年   1篇
  1987年   1篇
  1985年   2篇
  1984年   1篇
  1982年   3篇
  1978年   1篇
  1974年   2篇
  1966年   1篇
排序方式: 共有86条查询结果,搜索用时 15 毫秒
11.
Water Resources Management - The localization of the leaks is estimated using the time difference method in the past decade. Generalized and Basic Cross-correlation techniques are frequently...  相似文献   
12.
The structural diversity of polyphenols and the inherent limitations of current extraction techniques pose a challenge to extract polyphenols using a simple and green method. Hence, in this study, a method was developed to simultaneously fractionate multiple classes of polyphenols by only varying ethanol-water solutions. Honeybush tea, which is rich in polyphenols, was selected as a model for this study. Solvent extraction followed by solid-phase extraction (SPE) was developed to obtain a polyphenol-rich fraction from six honeybush samples. Based on a gradient elution programme (10%, 30%, 50%, 70% and 90% (v/v) ethanol-water solution) of SPE, the Strata X cartridge showed a better recovery of most targeted polyphenols under 0.9 mL of the drying volume and 1 mL min−1 of the dispensing speed. The elution programme for fractionating most polyphenols was as follows: single elution with 50% ethanol, followed by twice elution with 70% ethanol. The antioxidant capacity was used to analyse the differences among the polyphenol-rich fractions from six honeybush samples. Principal component analysis (PCA) revealed that unfermented C. genistoides (GG) has the greatest antioxidant capacity among the honeybush species studied. Additionally, mangiferin, isomangiferin and vicenin-2 were the main contributors to the antioxidant capacity in six honeybush fractions according to the correlation study.  相似文献   
13.
14.
Evolution of reactive oxygen species (ROS), generated during the patho-physiological stress of nervous tissue, has been implicated in the etiology of several progressive human neurological disorders including Alzheimer's disease (AD) and amylotrophic lateral sclerosis (ALS). In this brief communication we used mixed isomers of 5-(and-6)-carboxy-2',7'-dichlorofluorescein diacetate (carboxy-DCFDA; C(25)H(14)C(l2)O(9); MW 529.3), a novel fluorescent indicator, to assess ROS generation within human neuronal-glial (HNG) cells in primary co-culture. We introduced pathological stress using the sulfates of 12 environmentally-, industrially- and agriculturally-relevant divalent and trivalent metals including Al, Cd, Cu, Fe, Hg, Ga, Mg, Mn, Ni, Pb, Sn and Zn. In this experimental test system, of all the metal sulfates analyzed, aluminum sulfate showed by far the greatest ability to induce intracellular ROS. These studies indicate the utility of using isomeric mixtures of carboxy-H(2)DCFDA diacetates as novel and highly sensitive, long-lasting, cell-permeant, fluorescein-based tracers for quantifying ROS generation in intact, metabolizing human brain cells, and in analyzing the potential epigenetic contribution of different metal sulfates to ROS-generation and ROS-mediated neurological dysfunction.  相似文献   
15.
PURPOSE: To evaluate whether isoflurane is as suitable as sevoflurane for the single vital capacity breath (VCB) method of inhalational induction in patients premedicated with midazolam. METHODS: A randomised, controlled, double-blind study involving 67 ASA I-II patients aged between 18-50 yr undergoing elective surgery under general anaesthesia. All participants received premedication with 0.03 mg.kg-1 midazolam i.v. Using a primed circle absorber circuit, inhalational induction of anaesthesia was performed with the single VCB method using either isoflurane 3.5% or sevoflurane 7.5% in nitrous oxide 67% in oxygen, representing approximately equivalent MAC-multiples of 3.6 MAC. Isoflurane was compared with sevoflurane in terms of rapidity, efficacy, safety and acceptability of induction. RESULTS: With the single VCB method, sevoflurane produced a faster (45 +/- 21 vs 71 +/- 22 sec, P < 0.01), more successful (100% vs 75.8%, P < 0.01) induction of anaesthesia, with fewer induction-related complications (11.8% vs 84.8%, P < 0.01) than did isoflurane. There was also greater patient acceptability of induction with sevoflurane (76.4% vs 42.4%, P < 0.05). CONCLUSION: In adults given midazolam premedication, isoflurane is not as suitable as sevoflurane for single VCB inhalational anaesthetic induction technique as it is associated with slower, more complicated induction and less patient acceptability.  相似文献   
16.
Vaccines have shown significant promise in eliciting protective and therapeutic responses. However, most effective vaccines require several booster shots, and it is challenging to generate responses against synthetic molecules and peptides often used to increase target specificity and improve vaccine stability. As continuous antigen uptake and processing by antigen‐presenting cells and persistent toll‐like receptor priming can amplify humoral immunity, it is explored whether a single injection of a mesoporous silica micro‐rod (MSR) vaccine containing synthetic molecules and peptides can generate potent and durable humoral immunity. A single injection of the vaccine targeting a gonadotropin‐releasing hormone (GnRH) decapeptide elicits high anti‐GnRH titer for over 12 months and generated higher titers than bolus or alum formulations. Targeting a Her2/neu peptide within the Trastuzumab binding domain causes immunoreactivity to Her2 on tumor cells and, MSR vaccines against nicotine generated long‐term anti‐nicotine antibodies. A single MSR injection induced germinal center (GC) activity for more than 3 weeks, generated memory B cells, and 7 days of immunostimulation by the vaccine is required to generate effective antibody responses. The MSR vaccine represents a promising technology to bypass the need for multiple immunizations and enhance long‐term antibody production in the context of reproductive biology, cancer, and chronic addiction.  相似文献   
17.
Recanalization of occluded central veins for insertion of hemodialysis catheter is a particular attractive option in patients who are catheter dependent for hemodialysis, as it delays exhaustion of conventional venous accesses. Literature detailing techniques for catheter placement in recanalized veins remain sparse. We hereby describe a safe and economical technique of using dilator venotomy to allow catheter placement following successful recanalization.  相似文献   
18.
Genetic programming, in conjunction with advanced analytical instruments, is a novel tool for the investigation of complex biological systems at the whole-tissue level. In this study, samples from tomato fruit grown hydroponically under both high- and low-salt conditions were analysed using Fourier-transform infrared spectroscopy (FTIR), with the aim of identifying spectral and biochemical features linked to salinity in the growth environment. FTIR spectra of whole tissue extracts are not amenable to direct visual analysis, so numerical modelling methods were used to generate models capable of classifying the samples based on their spectral characteristics. Genetic programming (GP) provided models with a better prediction accuracy to the conventional data modelling methods used, whilst being much easier to interpret in terms of the variables used. Examination of the GP-derived models showed that there were a small number of spectral regions that were consistently being used. In particular, the spectral region containing absorbances potentially due to a cyanide/nitrile functional group was identified as discriminatory. The explanatory power of the GP models enabled a chemical interpretation of the biochemical differences to be proposed. The combination of FTIR and GP is therefore a powerful and novel analytical tool that, in this study, improves our understanding of the biochemistry of salt tolerance in tomato plants.  相似文献   
19.
Laparoscopic ultrasound has seen increased use as a surgical aide in general, gynecological, and urological procedures. The application of real-time, three-dimensional (RT3D) ultrasound to these laparoscopic procedures may increase information available to the surgeon and serve as an additional intraoperative guidance tool. The integration of RT3D with recent advances in robotic surgery also can increase automation and ease of use. In this study, a 1-cm diameter probe for RT3D has been used laparoscopically for in vivo imaging of a canine. The probe, which operates at 5 MHz, was used to image the spleen, liver, and gall bladder as well as to guide surgical instruments. Furthermore, the three-dimensional (3-D) measurement system of the volumetric scanner used with this probe was tested as a guidance mechanism for a robotic linear motion system in order to simulate the feasibility of RT3D/robotic surgery integration. Using images acquired with the 3-D laparoscopic ultrasound device, coordinates were acquired by the scanner and used to direct a robotically controlled needle toward desired in vitro targets as well as targets in a post-mortem canine. The rms error for these measurements was 1.34 mm using optical alignment and 0.76 mm using ultrasound alignment.  相似文献   
20.
Total colour difference (ΔE), rates of adsorbed moisture and sensory attributes of drum-dried jackfruit powder packaged in aluminium laminated polyethylene (ALP) and metallized co-extruded biaxially oriented polypropylene (BOPP/MCPP) pouches stored at accelerated storage (38 °C, with 50%, 75% and 90% relative humidity (RH)) were determined over 12 weeks period. The changes in total colour followed zero order reaction kinetics. Packaging materials, storage temperature and RH values significantly (p < 0.05) influenced the rates of adsorbed moisture of jackfruit powder. There was a significant (p < 0.05) decrease in the intensities of the fruity odour, taste and increase in the lumpiness of the jackfruit powder stored at 38 °C with 90% RH. The shelf life of jackfruit powder stored at 38 °C and 90% RH was limited by overall acceptability and the intensity of fruity odour, taste and lumpiness at week 8 of storage. Jackfruit powder stored at 28 °C remained stable and acceptable throughout the storage period for all RH values. The powder packaged in ALP significantly (p < 0.05) reduced total colour change, rates of adsorbed moisture, lumpiness intensity of jackfruit powder and was rated higher in terms of overall acceptability over BOPP/MCPP. Results of this study suggested that ALP packaging with storage conditions of 28 °C and RH less than 75% was better suited for keeping jackfruit powder.  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