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   171篇
  免费   20篇
工业技术   191篇
  2023年   4篇
  2022年   5篇
  2021年   19篇
  2020年   8篇
  2019年   12篇
  2018年   17篇
  2017年   17篇
  2016年   7篇
  2015年   8篇
  2014年   8篇
  2013年   20篇
  2012年   17篇
  2011年   13篇
  2010年   5篇
  2009年   6篇
  2008年   6篇
  2007年   2篇
  2006年   1篇
  2005年   2篇
  2004年   1篇
  2003年   1篇
  2002年   3篇
  1998年   3篇
  1996年   1篇
  1995年   1篇
  1994年   1篇
  1989年   1篇
  1987年   1篇
  1986年   1篇
排序方式: 共有191条查询结果,搜索用时 312 毫秒
61.
The efficacy of pistachio hull powder (PHP) prepared from agricultural waste was investigated in this study as a novel adsorbent for the elimination of dye molecules from contaminated streams. Removal of methylene blue (MB) as a cationic model dye by PHP from aqueous solution was studied under different experimental conditions. The selected parameters were solution pH (2–10), PHP dosage (0.5–3 g/L), MB concentrations (100–400 mg/L), contact time (1–70), and solution temperature (20–50 °C). The experimental results indicated that the maximum MB removal could be attained at a solution pH of 8. The dosage of PHP was also found to be an important variable influencing the MB removal percentage. The removal efficiency of MB improved from 94.6 to 99.7% at 70 min contact time when the MB concentration was decreased from 300 to 100 mg/L at a pH and PHP dosage of 8 and 1.5 g/L, respectively. The kinetic analysis showed that the pseudo-second-order model had the best fit to the experimental data. The Langmuir equation provided the best fit for the experimental data of the equilibrium adsorption of MB onto PHP at different temperatures. In addition, the maximum adsorption capacity increased from 389 to 602 mg/g when the temperature was increased from 20 to 50 °C. The thermodynamic evaluation of MB adsorption on PHP revealed that the adsorption phenomenon under the selected conditions was a spontaneous physical process. Accordingly, pistachio hull waste was shown to be a very efficient and low-cost adsorbent, and a promising alternative for eliminating dyes from industrial wastewaters.  相似文献   
62.
Effects of conventional polysiloxane additives and nano-SiO2 on the mechanical properties of an automotive acrylic/melamine clearcoat (CC) are studied. Clearcoats formulations were prepared by addition of different concentrations of polysioloxane additives (with different modifications) and hydrophobic nano-SiO2 particles. Attenuated Total Reflection-Fourier Transform Infrared (ATR-FTIR) and atomic force microscope (AFM) were utilized to evaluate the effects of nano-SiO2 and polysiloxane additives on the surface properties of the CCs. The mechanical properties of the surface and the bulk of the CCs were studied by nano-indentation and tensile tests, respectively. Results showed that polysiloxane additives can mostly affect the mechanical properties of the surface of the CC. Additives with shorter side chains and therefore higher surface activity caused higher changes on the surface properties the CC. Unlike conventional polysiloxane additives, the nano-SiO2 particles mainly influenced the mechanical properties of the bulk of the CC.  相似文献   
63.
In most of tall buildings, the main contribution of lateral loads is carried by coupled shear walls. In some cases, the necessary stiffness to withstand the lateral load may not be afforded due to low depth of connecting beams. In order to increase the capacity of the coupled shear walls, beams with high stiffness are added to the system at particular levels. Hence, stiffened coupled shear walls (SCSW) will be produced. Such walls are under axial load resulting from their weight, and this axial load affects the behavior of walls because of their excessive height. In this paper, a new method considering the effect of axial force for geometrically nonlinear analysis of the SCSW has been presented. A computer program has been developed in matlab , and numerical examples have been solved to demonstrate the reliability of this method. The results of the examples show the agreement between the present method and the other methods given in the literature. The effects of the various positions and rigidities of the stiffening beam on the internal forces and the lateral deflection of the structure considering axial force effect have also been investigated. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   
64.
An experimental model of proliferative vitreoretinopathy was developed in the rabbit eye by injecting a solution of human platelet-rich plasma. In this model we evaluated the progression with time of intraocular inflammation and the rate and origin of cell proliferation. A sterile solution adjusted to 107 platelets was injected into the right eye of a total of 46 pigmented and 14 albino rabbits. Animals were sequentially sacrificed at days 7, 14, 21 and 1 month after injection. Clinical evaluation of vitreoretinal proliferation, using a classification in six grades, and of anterior segment inflammation assessed by a Laser Flare Meter, were done for 1 month after injection, before histopathological analysis. Eighty percent of eyes developed tractional retinal detachment in 1 month. Histopathology showed intense cell migration and proliferation in the area of the ciliary body, as early as the seventh day, then further increasing rapidly. Infiltrates were composed of cytokeratin- and vimentin-expressing cells. Abnormal expression of vimentin was also found in ciliary and retinal epithelia and in M?ller cells. Inflammation measured by the Laser Flare Meter was maximal at day 11 and then reached a plateau at significantly higher levels than controls. Albino rabbits showed significantly lower grades of proliferation, as compared to pigmented rabbits. This study thus clarified some characteristics of experimental vitreoretinal proliferations that that proved similar to those in human diseases, such as the involvement of ciliary body and retinal pigment epithelium, the existence of inflammatory reactions preceding cell proliferation and strong changes in intermediate filaments. This may provide a simple and valuable model for antiproliferative assays and shed some light on the pathogenesis of intraocular proliferative disorders.  相似文献   
65.
To facilitate broader applications of insulin-like growth factor I (IGF-I) and IGF-binding protein-3 (IGFBP-3) analysis, we developed procedures for their measurements in extracts of whole blood dried on filter paper. A single 8-mm diameter filter paper disc containing about 13 microL blood was used. IGFBP-3 was efficiently extracted in a buffer within 1 h of incubation. IGF-I extraction involved incubation in buffer followed by acidification and neutralization steps. Blood spot assays showed intra- and interassay coefficients of variation (including interspot variations) of 5.4-16.7% for IGF-I and 6.6-11.7% for IGFBP-3; recoveries were 97 +/- 7.1% and 101 +/- 8.7%, respectively. Recoveries of IGF-I and IGFBP-3 in response to 4- to 8-fold variations in extraction buffer volume were 97 +/- 8.2% and 107 +/- 6.1%, respectively. Dried blood spot IGF-I and IGFBP-3 showed greater than 1-month stability at -20 C, 4 C, and room temperature and retained more than 65% of the immunoreactivity after approximately 1 month at 37 C. Both IGF-I and IGFBP-3 were contained within the plasma fraction of whole blood, and variations (mean +/- SD) in IGF-I (204 +/- 29 micrograms/L) and IGFBP-3 (4.4 +/- 0.48 mg/L) measured in extracts of dried blood spot with adjusted hematocrit of 0.2-0.62 were acceptable. IGF-I and IGFBP-3 in paired plasma and dried blood spot extracts of random samples (n = 46) showed excellent correlation (r > 0.94) with slopes of near unity. Compared to conventional methods, the filter paper procedures were equally effective in distinguishing IGF-I and IGFBP-3 levels in untreated GH receptor-deficient (n = 11) and age-matched normal controls (n = 16). We conclude that blood collected on filter paper is ideal for IGF-I and IGFBP-3 analysis and may find applications in pediatric and large scale infant screening programs.  相似文献   
66.
It is a practice to add microalgae into plain and probiotic fermented milks in order to promote the functionality of these products via their direct health effects as well as the enhancing impact on viability of probiotic microorganisms in product and in gastrointestinal tract. In this study, the effects of addition of two species of microalgae including Arthrospira platensis and Chlorella vulgaris (seven yogurt treatments containing three concentrations for each microalgae—0.25, 0.50, and 1.00?%—and a control without microalgae) on pH, titrable acidity, and redox potential changes as well as on the viability of probiotic bacteria during fermentation and during a 28-day refrigerated storage period (5?°C) were investigated in yogurt. Also, the amounts of lactic and acetic acids at the end of fermentation were assessed. The culture composition of yogurt was ABY type, containing Lactobacillus acidophilus LA-5, Bifidobacterium lactis BB-12, Lactobacillus delbrueckii ssp. bulgaricus, and Stresptococcus themophilus. The addition of microalgae significantly (p?<?0.05) increased the viability of L. acidophilus and bifdobacteria at the end of fermentation and during the storage period. Treatments containing A. platensis had slower pH decline, faster acidity increase, longer incubation time, and greater final titrable acidity than those containing C. vulgaris and control. In treatments containing 0.5 or 1?% microalgae, the viability was almost higher than 107 cfu/mL until the end of refrigerated storage.  相似文献   
67.
Viability of probiotic bacteria during the production and storage of fermented milks is the most important topic of discussion in the dairy industry. Addition of microalgae into milk for the production of fermented milk in order to enhance the viability of probiotics has been the subject of recent research. Spirulina and Chlorella are the most widely noted microalgae for fermented milks. They affect not only the viability of probiotics in final product but also the sensory attributes of them. Incorporation of microalgae into probiotic fermented milks along with enhancing the viability of probiotics would increase their functional characteristic. This is because they contain a wide range of nutrients and nutraceuticals and are considered as “functional food.” This article reviews the effects of supplementation of Spirulina platensis and Chlorella vulgaris into probiotic fermented milks on their different quality characteristics.  相似文献   
68.
Through a simple and rapid method, carbon papers (CPs) were coated with Au and the resulting Au/CP substrates were used for the preparation of Pt/Au/CP by Cu underpotential deposition (Cu UPD) and redox replacement technique. A series of Ptn/Au/CP catalysts (where n = number of UPD-redox replacement cycles) were synthesized and their electrochemical properties for methanol oxidation reaction (MOR), and oxygen reduction reaction (ORR) were investigated by electrochemical measurements. The Ptn/Au/CP electrodes show higher electrocatalytic activity and enhanced poison tolerance for the MOR as compared to a commercial Pt/C on CP (Pt/C/CP). The highest mass specific activity and Pt utilization efficiency for MOR was observed on Pt1/Au/CP with a thickness close to a monatomic Pt layer. Chronoamperometric tests in methanol solution revealed that Ptn/Au/CPs have much higher CO tolerance compared to Pt/C/CP. Among the Ptn/Au/CPs, CO tolerance decreases with increasing the amount of deposited Pt, indicating that the exposed Au atoms in close proximity to Pt plays a positive role against CO poisoning. Compared with the Pt/C/CP, all the Ptn/Au/CP electrodes show more positive onset potentials and lower overpotentials for ORR. For instance, the onset potential of ORR is 150 mV more positive and the overpotential is ∼140 mV lower on Pt4/Au/CP with respect to Pt/C/CP.  相似文献   
69.
Hypertension is a major risk factor for cardiovascular disease, myocardial infarction, stroke and renal failure. Sesame consumption may benefit blood pressure (BP ) owing to its high polyunsaturated fatty acid, fibre, phytosterol and lignan contents. To clarify this, a systematic review and meta‐analysis of controlled trials was conducted. The PubMed (MEDLINE ), Cumulative Index to Nursing and Allied Health Literature (CINAHL ) and Cochrane Library (Central) databases were systematically searched until August 2016. Eight controlled trials with a total of 843 participants met the eligibility criteria. A random effect meta‐analysis showed that sesame consumption can reduce systolic BP (?7.83 mmHg , 95% CI : ?14.12, ?1.54; P < 0.05, I 2 = 99%) and diastolic BP (?5.83 mmHg, 95% CI: ?9.58, ?2.08; P < 0.01, I 2 = 98%). To reduce the heterogeneity, the meta‐analysis was limited to high methodology quality trials (n = 4), which resulted in a significant reduction in systolic BP (?3.23 mmHg, 95% CI: ?5.67, ?0.79; I 2 = 33%) and a non‐significant reduction in diastolic BP (?2.08 mmHg, 95% CI: ?4.85, 0.69; I 2 = 62%). This study concluded that sesame consumption can reduce systolic and diastolic BP. However, further investigations with larger sample sizes and better methodology quality are required to confirm the BP‐lowering effect of sesame consumption. © 2017 Society of Chemical Industry  相似文献   
70.
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