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   20617篇
  免费   2050篇
  国内免费   337篇
电工技术   144篇
综合类   925篇
化学工业   4010篇
金属工艺   292篇
机械仪表   448篇
建筑科学   434篇
矿业工程   187篇
能源动力   839篇
轻工业   12749篇
水利工程   45篇
石油天然气   378篇
武器工业   39篇
无线电   231篇
一般工业技术   1063篇
冶金工业   377篇
原子能技术   252篇
自动化技术   591篇
  2024年   108篇
  2023年   410篇
  2022年   737篇
  2021年   993篇
  2020年   962篇
  2019年   884篇
  2018年   813篇
  2017年   776篇
  2016年   791篇
  2015年   834篇
  2014年   1070篇
  2013年   1428篇
  2012年   1613篇
  2011年   1489篇
  2010年   988篇
  2009年   947篇
  2008年   846篇
  2007年   1154篇
  2006年   1090篇
  2005年   876篇
  2004年   717篇
  2003年   648篇
  2002年   550篇
  2001年   370篇
  2000年   284篇
  1999年   263篇
  1998年   192篇
  1997年   184篇
  1996年   102篇
  1995年   114篇
  1994年   107篇
  1993年   100篇
  1992年   115篇
  1991年   43篇
  1990年   49篇
  1989年   41篇
  1988年   36篇
  1987年   41篇
  1986年   37篇
  1985年   40篇
  1984年   32篇
  1983年   12篇
  1982年   21篇
  1981年   12篇
  1980年   24篇
  1979年   9篇
  1977年   8篇
  1976年   11篇
  1975年   14篇
  1973年   7篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
王海宁  池卓哲 《包装工程》2021,42(12):84-90, 97
目的 为了更科学地研究和检验可穿戴产品的适合性,提出一种适合性检验方法,能够精确保留现实环境中的产品佩戴关系,并能将现实与虚拟的适合性检验研究相结合,得到合理的适合性检验结果.方法 以虚拟现实眼镜的适合性检验为例,通过高精度的三维测量技术将现实环境中的人、产品以及人—产品佩戴关系转化为三维虚拟信息,并以人—产品佩戴三维模型为参考基准对齐人和产品的虚拟模型,得到保留现实佩戴关系的人—产品佩戴模型组,再应用偏差分析法得出人—机佩戴区域的可视化适合性结果和统计数据,结合主观评价方法进一步分析产品的适合性.结论 虚实结合的产品适合性检验方法可在虚拟环境中高精度地保留现实环境中的人—产品佩戴关系,并能得到可视化的适合性检验结果,为检验和指导产品的适合性提供依据.  相似文献   
2.
3.
4.
5.
Soybean hulls, the main byproduct in soybean processing, have many biological activities. However, the value of this byproduct is still far from being fully exploited. In this study, we investigated the anti-tyrosinase and antioxidant capacities in soybean hulls fermented by Lactobacillus plantarum ZLC-18 (L. plantarum ZLC-18). We found that L. plantarum ZLC-18 fermentation could markedly improve the anti-tyrosinase and antioxidant activities of soybean hulls. The anti-tyrosinase and antioxidant activities were positively correlated with the total phenolic and flavonoid contents. UPLCMS analysis suggested that phenolic compounds (daidzin, genistin, vanillic acid and so on) were increased in soybean hulls after fermentation, and some of these compounds were shown to have anti-tyrosinase and antioxidant activities. Our study demonstrates that fermentation is an efficient strategy to enhance the bioactive function of soybean hulls. Moreover, this study provides evidence that soybean hulls can be used as a kind of functional food ingredient, thereby improving their economic benefits.  相似文献   
6.
Brown rice noodles (RN) are typical whole-grain products with health benefits. This study investigated the effects of rice bran fermented with Lactobacillus plantarum on palatability, volatile profiles, and antioxidant activity of brown RN. Three kinds of RN, including RN, brown RN (BRN), and bran fermented RN (BFRN), were involved in this study. The results indicated that bran fermentation reduced the cooking loss of BFRN and improved the elongation and the sensory attributes of brown RN. After fermentation, aldehydes were significantly decreased while alcohols increased, and more pleasant flavours were shown in BFRN. Fermentation increased the content of free phenolics and decreased the content of bound phenolics. Among the four major phenolics detected in this study, ferulic acid was the most abundant one in all three RN samples. The DPPH radical scavenging activity and the ferric reducing antioxidant power of free phenolics in BFRN increased significantly compared to BRN. This study proved that rice bran fermentation is an effective approach to improve palatability, enrich the flavour as well as enhance the antioxidant activity of brown RN, which may facilitate the development of processing technology for brown RN.  相似文献   
7.
陈文雯 《包装工程》2022,43(24):269-276
目的 针对目前市面上都江堰旅游产品识别性较弱、同质化严重,对具有地域文化特色的旅游产品开发较少的问题,以地域文化元素作为都江堰旅游产品设计的核心,提出旅游产品的设计策略。方法 研究都江堰旅游产品设计,应从地域化和文化内涵入手。通过分析旅游产品现状,地域文化元素及新旅游时代背景下旅游产品的发展趋势,结合情感化设计理念,围绕用户体验进行探究,总结出都江堰旅游产品设计开发模式。以李冰石像和鱼嘴段水利工程元素为例,进行产品实践。结论 提出符合都江堰区域特色的旅游产品设计策略,即树立品牌意识、打造IP形象,以地域文化元素为设计核心,加强情感互动、与科技相融合的设计策略。赋予旅游产品更深层次的内涵,打造更多具有地域文化特色的旅游产品,从而推动历史文化与商业价值的融合,也能够为同类型旅游产品提供具有应用价值和参考的设计策略和思路。  相似文献   
8.
In recent years, alternative renewable energy generation sources have been investigated, highlighting the dark fermentation process due to it’s potential to obtain hydrogen-rich gas, which can be used as an energy source. Different trace metals intervene in this biological process. Nickel is one of the most important because it is a component of the [Ni–Fe] hydrogenase enzyme that catalyzes the oxidation of H2 in numerous bacteria. The aim of this study was to evaluate the effect of nickel on biohydrogen production from organic solid waste (OSW). The experimental setup was carried out in batch tests using OSW as the substrate, glucose as a reference compound and the valuation of Ni2+ doses on the operation in a Sequencing Batch Reactor. The results of the batch tests showed that when using glucose as a substrate, 2 mg Ni2+/g VSinoculum generated the highest hydrogen production (774 ± 7.3 mL H2/L/d) and highest yield (55.8 ± 3.4 mL H2/g of glucose), which was 34.4% higher than the control. Testing of different concentrations of nickel using OSW as a carbon source showed that the highest production was obtained without Ni2+ addition since the nickel concentration in the residue was 0.17 ± 0.06 mgNi/gVS; consequently, hydrogen production was not affected by the lack of Ni. The addition of 0.5 mg Ni2+/g VSinoculum decreased acetate and butyrate production and increased caproate production.  相似文献   
9.
According to the International Energy Agency, only a small part of the full potential of biomass energy is currently used in the world. The annual amount of agricultural waste in the Russian Federation is estimated at about 152 million tons, and the energy potential of animal waste is 201 PJ/year. Anaerobic digestion is an efficient method of converting organic waste into renewable energy sources. Previously, the positive effect of pretreatment of various organic feedstocks in vortex layer apparatus (VLA) on the characteristics of anaerobic digestion and energy efficiency was shown. Currently, there is a significant interest in the world in obtaining biohydrogen from organic waste using the dark fermentation (DF) process. During pretreatment in the VLA, the iron working bodies are abraded and iron particles are introduced into the feedstock of the DF reactor. This may have a positive effect on the production rate and yield of hydrogen, which has not been previously studied. This work is aimed at evaluating the possibility of using the VLA as a method for pretreatment of a dark fermentation feedstock for the intensification of biohydrogen production. To achieve this goal, an experimental setup was constructed. It consisted of a 45 L DF reactor, a VLA and a process control system to collect data on the DF process parameters every 5 min. At a hydraulic retention time in the DF reactor of 24 h and in the VLA of 30 s, the hydrogen content in the biogas increased from 51.1% to 52.2%. At the same time, the pH increased from 3.85 to 4.8–4.9, and the hydrogen production rate increased by 16% to 1.941 L/(L day). The hydrogen yield was 80.9 ml/g VS. Thus, pretreatment of the feedstock in VLA can be an effective way to intensify the DF process; however, further study of the VLA operating modes is required in order to optimize the concentrations of iron particles introduced into the feedstock for the most efficient continuous production of dark fermentative biohydrogen.  相似文献   
10.
This study investigated the inhibitory effects of curcumin and piperine on fluorescent advanced glycation end products (fAGEs) formation in a bovine serum albumin (BSA)–fructose model. Model systems of BSA and fructose were prepared, and curcumin or piperine was added. fAGEs and BSA oxidation product (dityrosine, kynurenine and N'-formylkynurenine) contents were determined. The results showed that fAGEs content decreased with increasing concentration of curcumin and piperine (P < 0.05). Addition of curcumin and piperine at 160 µg mL−1 could inhibit fluorescent AGEs by 100% and 93% respectively. Dityrosine and N'-formylkynurenine contents decreased as curcumin and piperine concentration increased (P < 0.05). Furthermore, the result of principal component analysis indicated that curcumin and piperine markedly impeded BSA oxidation, resulting in a lower level of fAGEs in model systems. Therefore, adding curcumin and piperine may facilitate reduced fAGEs levels in BSA–fructose model.  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