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   9727篇
  免费   702篇
  国内免费   101篇
电工技术   227篇
综合类   866篇
化学工业   917篇
金属工艺   66篇
机械仪表   117篇
建筑科学   212篇
矿业工程   24篇
能源动力   27篇
轻工业   6402篇
水利工程   41篇
石油天然气   21篇
武器工业   14篇
无线电   453篇
一般工业技术   448篇
冶金工业   32篇
原子能技术   23篇
自动化技术   640篇
  2024年   5篇
  2023年   61篇
  2022年   180篇
  2021年   235篇
  2020年   295篇
  2019年   193篇
  2018年   177篇
  2017年   273篇
  2016年   276篇
  2015年   241篇
  2014年   438篇
  2013年   721篇
  2012年   650篇
  2011年   743篇
  2010年   457篇
  2009年   518篇
  2008年   381篇
  2007年   726篇
  2006年   708篇
  2005年   630篇
  2004年   468篇
  2003年   377篇
  2002年   349篇
  2001年   271篇
  2000年   214篇
  1999年   176篇
  1998年   151篇
  1997年   123篇
  1996年   85篇
  1995年   83篇
  1994年   109篇
  1993年   43篇
  1992年   43篇
  1991年   29篇
  1990年   27篇
  1989年   25篇
  1988年   16篇
  1987年   14篇
  1986年   7篇
  1984年   3篇
  1983年   1篇
  1982年   2篇
  1980年   1篇
  1979年   2篇
  1978年   1篇
  1977年   1篇
  1976年   1篇
排序方式: 共有10000条查询结果,搜索用时 78 毫秒
1.
Under the circumstance of perceptual consumption, it is still challenging to grasp consumer's emotions and demands due to the large search space, diversified preferences, and easy fatigue of consumers. To reduce user fatigue and enlarge search space, a novel method was presented to design and optimize the pattern of yarn-dyed plaid fabric using the isolation niche genetic algorithm and rough set theory. Each pattern was encoded as a chromosome based on the real number code. The population was initialized and evolved using INGA to maintain the diversity. The rough set theory was adopted as the fitness function of isolation niche genetic algorithm to extract the consumer's demands. After multiple evolutions, a large set of practical patterns of the yarn-dyed plaid fabric are obtained. Experiments were carried out by 24 testers of different ages and genders. The results prove that the proposed method based on the isolation niche genetic algorithm and rough set theory is feasible and effective, supplying references to the designer.  相似文献   
2.
Yarn-dyed fabric is often woven from warp and weft yarns in the same color depth to ensure a uniform color appearance. The difference in color depth between warp and weft tends to result in the uneven color of the yarn-dyed fabric. This article aims to establish a color tolerance for yarn-dyed fabric that can be woven with a qualified color appearance but from the warp and weft yarns in different color depths. A total of 27 yarn-dyed fabric samples in three color series (red, yellow, and blue) were evaluated by using the yarn-dyed fabric from warp and weft yarns in the same color depth of 2% (on weight of fabric, owf) as the standard. Visual assessment and instrumental measurement of color were carried out to establish the color tolerance ellipse that was defined as CMC (Color Measurement Committee) color differences (2:1) of no more than 1.00. It was found that the color strengths (K/S) and color differences (ΔECMC(2:1)) of these fabric samples for each color series had linear relationships with the color depths of warp and weft yarns. The color tolerance ellipses indicated that, even though the warp and weft yarns had an apparent color difference, they could be woven in fabrics with relatively uniform color appearance and meet the requirements for yarn-dyed fabric. This work provided valuable insight into the production of qualified yarn-dyed fabrics from unqualified dyed yarns.  相似文献   
3.
以我校《现代交换技术》课程教学过程中存在的问题进行分析和总结,并结合目前行业发展的需求,对该课程的教学内容设计、教学方法的改进、实践教学内容和设备等各方面给出了相应的改革思路和解决方案。  相似文献   
4.
为给纺织行业在纺织品贸易和质量控制等方面优选色差公式提供参考,研究了3个重要的和1个最新色差公式的色差均匀性,借助国际上色样多、视觉等距性好的汉风色典,利用X-Rite测色仪测试近2万个色样的色度参数,然后分别从向度、彩度、浓度3个方向选取3万多对相邻色样,采用MatLab编程计算4种色差并统计分析其均值、不匀率和性能因子。结果表明:不同方向不同评价指标所得结果不尽相同;在色差均匀性方面,CAM16-UCS最好,CIEDE2000(2∶1∶1)略优于CMC(2∶1),且二者明显优于CIELAB;在色差大小方面由小到大依次为CIEDE2000(2∶1∶1)、CMC(2∶1)、CAM16-UCS、CIELAB。  相似文献   
5.
Membrane technology has been considered a key factor for sustainable growth in high-efficiency gas separation. Current mixed matrix membranes (MMMs) technology is rising, but these membranes in the dense structure are having difficulties in operating at high pressures and scale up for commercialization. The purpose of this research is to synthesize composite MMMs (CMMMs) consisting of polyethersulfone (PES), carbon molecular sieve (CMS 1–5 wt %), and Novatex 2471 nonwoven fabric (support layer). The membranes' physical, chemical, and thermal properties were evaluated by different analytical equipment. The morphology of both PES and PES-CMS composite membranes had a porous and asymmetric structure, in which CMS was uniformly distributed in the polymer matrix. The thermal properties showed that the membranes were stable up to 350 °C with a single glass transition temperature. The functional groups in the membrane were confirmed by spectral analysis. The gas performance results showed that carbon dioxide permeance increased with increased CMS concentration and methane permeance decreased due to the hindering effect of CMS under similar operating conditions. The highest selectivity achieved was 12.774 using CMMM of 5 wt % of CMS at 10 bar, which on average was 137.80%, improved selectivity compared to pure PES membrane. The support layer was able to withstand high operating pressures and showed the ability to scale up. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48476.  相似文献   
6.
In this research, the three‐dimensional structural and colorimetric modeling of three‐dimensional woven fabrics was conducted for accurate color predictions. One‐hundred forty single‐ and double‐layered woven samples in a wide range of colors were produced. With the consideration of their three‐dimensional structural parameters, three‐dimensional color prediction models, K/S‐, R‐, and L*a*b*‐based models, were developed through the optimization of previous two‐dimensional models which have been reported to be the three most accurate models for single‐layered woven structures. The accuracy of the new three‐dimensional models was evaluated by calculating the color differences ΔL*, ΔC*, Δh°, and ΔECMC(2:1) between the measured and the predicted colors of the samples, and then the error values were compared to those of the two‐dimensional models. As a result, there has been an overall improvement in color predictions of all models with a decrease in ΔECMC(2:1) from 10.30 to 5.25 units on average after the three‐dimensional modeling.  相似文献   
7.
韩雪  王帅  周小红 《合成纤维》2020,49(1):36-40
采用普通涤纶、含1%云母颗粒的涤纶(1%云母/涤纶)以及含5%云母颗粒的涤纶(5%云母/涤纶)三种材质,上机纬密采用200根/10 cm、300根/10 cm、400根/10 cm,组织采用平纹、斜纹、缎纹试织试样。通过Hot Disk热常数分析仪,采用正交试验及极差、方差分析,研究了纤维材质、上机纬密、组织对凉感纤维织物导热系数的影响。结果表明:在试验设置变量范围内,纤维材质对导热系数的影响显著,上机纬密、组织对导热系数的影响高度显著,影响因素从大到小顺序为上机纬密>组织>纤维材质。  相似文献   
8.
采用含黑色着色剂的涂层浆对尼龙6织物进行湿法涂层,通过测定着色剂在涂层浆中的稳定性及着色剂对涂层织物的着色性和色牢度等性能,研究了黑色着色剂种类、着色剂复配比例及用量、分散剂种类及用量对湿法涂层性能的影响。试验结果表明:炭黑301和中性染料S-RR在湿法涂层中的应用性能较好,并对其进行复配研究,确定中性染料S-RR和炭黑301的复配比例为3∶1,用量为8g;分散剂为TS100,用量为1.0g。  相似文献   
9.
张毅  姜迎雪  张昊 《化工进展》2020,39(7):2810-2816
以三乙胺和环氧氯丙烷为原料,合成醚化剂3-氯-2-羟丙基三乙基氯化铵。以甲壳素为原料通过醚化反应合成了季铵型甲壳素(CCT),再经脱乙酰得到季铵型阳离子改性壳聚糖(CCTS)。采用红外光谱(FTIR)、核磁碳谱(13C NMR)对其化学结构进行了表征,运用黏度法和分光光度法测定了黏均分子量和溶解性等理化性能。采用最小抑菌法对CCTS的抗菌活性进行了测定,得到其对大肠杆菌的最低有效抑菌浓度(MIC)为0.2g/L,优于天然壳聚糖的MIC值。以柠檬酸为交联剂、次磷酸钠为催化剂,用CCTS对兔毛织物进行抑菌整理,考察织物经整理的抑菌效果和耐洗性。经5次洗涤后结果表明,CCTS对大肠杆菌的抑菌率达99.9%以上,抑菌率高于CCT和天然壳聚糖,是一种针对动物毛织物良好的天然高分子长效抑菌整理剂。  相似文献   
10.
This study investigates the impact of lighting colors on subjective judgments of fabric: in particular, whether the influence of lighting varies depending on fabric types and color combinations. We conducted two visual assessments. In Study 1 (N = 44), eight illuminants and six types of fabric were presented as cloth stimuli. Derived from the literature review, four sets of adjectives (humble-luxurious, cool-warm, old-new, and not preferred-preferred) were used as metrics. In Study 2 (N = 41), five sets of fabric color combination swatches were assessed under lighting conditions that were identical to those of Study 1. Three bipolar scales (ordinary-characterful, classic-modern, and soft-rigid), were employed from factor analysis along with three unipolar scales (luxurious, preferred, harmonious with lighting). The results showed that hue characteristics of lighting and cloth types influenced participants' perceptions of the fabric. Overall, white lighting with 4000 K was the most preferred and luxurious lighting across various types of clothes, while a pinkish white with 4700 K (duv = −0.0127) was the best matched in every color combination. In addition, there were interaction effects between lighting colors, clothes types, and fabric color combinations with regard to each of the perceptual qualities. This study provides empirical evidence for optimally match lighting colors with fabric in the presentation of fabric goods.  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