全文获取类型
收费全文 | 305762篇 |
免费 | 6272篇 |
国内免费 | 952篇 |
专业分类
电工技术 | 5776篇 |
综合类 | 392篇 |
化学工业 | 47083篇 |
金属工艺 | 12189篇 |
机械仪表 | 11617篇 |
建筑科学 | 7146篇 |
矿业工程 | 1098篇 |
能源动力 | 8405篇 |
轻工业 | 26556篇 |
水利工程 | 2784篇 |
石油天然气 | 3979篇 |
武器工业 | 70篇 |
无线电 | 41964篇 |
一般工业技术 | 59925篇 |
冶金工业 | 50140篇 |
原子能技术 | 6024篇 |
自动化技术 | 27838篇 |
出版年
2021年 | 3486篇 |
2020年 | 2576篇 |
2019年 | 3184篇 |
2018年 | 4862篇 |
2017年 | 4914篇 |
2016年 | 5421篇 |
2015年 | 3582篇 |
2014年 | 6081篇 |
2013年 | 14183篇 |
2012年 | 9688篇 |
2011年 | 12626篇 |
2010年 | 9672篇 |
2009年 | 10624篇 |
2008年 | 11294篇 |
2007年 | 10613篇 |
2006年 | 9671篇 |
2005年 | 8707篇 |
2004年 | 8321篇 |
2003年 | 8123篇 |
2002年 | 7606篇 |
2001年 | 7493篇 |
2000年 | 7071篇 |
1999年 | 7103篇 |
1998年 | 15683篇 |
1997年 | 11195篇 |
1996年 | 8853篇 |
1995年 | 6910篇 |
1994年 | 6128篇 |
1993年 | 5937篇 |
1992年 | 4804篇 |
1991年 | 4445篇 |
1990年 | 4276篇 |
1989年 | 3999篇 |
1988年 | 3802篇 |
1987年 | 3324篇 |
1986年 | 3177篇 |
1985年 | 3713篇 |
1984年 | 3460篇 |
1983年 | 3086篇 |
1982年 | 2880篇 |
1981年 | 2986篇 |
1980年 | 2786篇 |
1979年 | 2675篇 |
1978年 | 2528篇 |
1977年 | 2975篇 |
1976年 | 3608篇 |
1975年 | 2329篇 |
1974年 | 2327篇 |
1973年 | 2334篇 |
1972年 | 1860篇 |
排序方式: 共有10000条查询结果,搜索用时 453 毫秒
51.
52.
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
53.
Eui Dae Jung Amit Kumar Harit Do Hui Kim Chung Hyeon Jang Jong Hyun Park Shinuk Cho Myoung Hoon Song Han Young Woo 《Advanced materials (Deerfield Beach, Fla.)》2020,32(30):2002333
A series of anionic conjugated polyelectrolytes (CPEs) is synthesized based on poly(fluorene-co-phenylene) by varying the side-chain ionic density from two to six per repeat units (MPS2-TMA, MPS4-TMA, and MPS6-TMA). The effect of MPS2, 4, 6-TMA as interlayers on top of a hole-extraction layer of poly(bis(4-phenyl)-2,4,6-trimethylphenylamine (PTAA) is investigated in inverted perovskite solar cells (PeSCs). Owing to the improved wettability of perovskites on hydrophobic PTAA with the CPEs, the PeSCs with CPE interlayers demonstrate a significantly enhanced device performance, with negligible device-to-device dependence relative to the reference PeSC without CPEs. By increasing the ionic density in the MPS-TMA interlayers, the wetting, interfacial defect passivation, and crystal growth of the perovskites are significantly improved without increasing the series resistance of the PeSCs. In particular, the open-circuit voltage increases from 1.06 V for the PeSC with MPS2-TMA to 1.11 V for the PeSC with MPS6-TMA. The trap densities of the PeSCs with MPS2,4,6-TMA are further analyzed using frequency-dependent capacitance measurements. Finally, a large-area (1 cm2) PeSC is successfully fabricated with MPS6-TMA, showing a power conversion efficiency of 18.38% with negligible hysteresis and a stable power output under light soaking for 60 s. 相似文献
54.
55.
Pasquale Stano Tereza Pereira de Souza Paolo Carrara Emiliano Altamura Erica D’Aguanno Margherita Caputo 《先进材料力学与结构力学》2015,22(9):748-759
Here we report some recent biophysical issues on the preparation of solute-filled lipid vesicles and their relevance to the construction of “synthetic cells.” First, we introduce the “semi-synthetic minimal cells” as the liposome-based cell-like systems, which contain a minimal number of biomolecules required to display simple and complex biological functions. Next, we focus on recent aspects related to the construction of synthetic cells. Emphasis is given to the interplay between the methods of synthetic cell preparation and the physics of solute encapsulation. We briefly introduce the notion of structural and compositional “diversity” in synthetic cell populations. 相似文献
56.
Effect of gums on viability and β‐galactosidase activity of Lactobacillus spp. in milk drink during refrigerated storage
下载免费PDF全文
![点击此处可从《International Journal of Food Science & Technology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Bernice D. Karlton‐Senaye Reza Tahergorabi Valerie L. Giddings Salam A. Ibrahim 《International Journal of Food Science & Technology》2015,50(1):32-40
The viability and β‐galactosidase activity of four Lactobacillus strains in milk drink containing gums during 28 days of refrigerated storage at 4 °C were assessed. The population of Lactobacillus rhamnosus GGB101 and Lactobacillus rhamnosus GGB103 were maintained, whereas the population of Lactobacillus reuteri DSM20016 and Lactobacillus reuteri SD2112 significantly decreased. The recommended level of 6 log CFU g?1 was exceeded for all tested trains throughout storage. The highest viable number of Lactobacillus rhamnosus GGB103 (8.76 ± 0.03 log CFU mL?1) was obtained in the product containing carrageenan–maltodextrin. The addition of guar–locust bean–carrageenan led to 20‐fold increase in the level of β‐galactosidase activity for L. rhamnosus GGB101 (1208 ± 2.12 Miller units mL?1) compared to the control (61 ± 2.83 Miller units mL?1). Our results suggested that gums could be added to milk to improve viability and enhance β‐galactosidase activity of Lactobacillus. 相似文献
57.
58.
59.
60.