全文获取类型
收费全文 | 1167篇 |
免费 | 85篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 17篇 |
综合类 | 2篇 |
化学工业 | 221篇 |
金属工艺 | 39篇 |
机械仪表 | 100篇 |
建筑科学 | 20篇 |
能源动力 | 60篇 |
轻工业 | 120篇 |
水利工程 | 2篇 |
石油天然气 | 1篇 |
无线电 | 219篇 |
一般工业技术 | 233篇 |
冶金工业 | 65篇 |
原子能技术 | 10篇 |
自动化技术 | 145篇 |
出版年
2024年 | 2篇 |
2023年 | 24篇 |
2022年 | 21篇 |
2021年 | 31篇 |
2020年 | 30篇 |
2019年 | 36篇 |
2018年 | 34篇 |
2017年 | 31篇 |
2016年 | 39篇 |
2015年 | 41篇 |
2014年 | 69篇 |
2013年 | 97篇 |
2012年 | 80篇 |
2011年 | 92篇 |
2010年 | 76篇 |
2009年 | 82篇 |
2008年 | 67篇 |
2007年 | 48篇 |
2006年 | 45篇 |
2005年 | 41篇 |
2004年 | 35篇 |
2003年 | 31篇 |
2002年 | 32篇 |
2001年 | 28篇 |
2000年 | 15篇 |
1999年 | 15篇 |
1998年 | 24篇 |
1997年 | 9篇 |
1996年 | 16篇 |
1995年 | 14篇 |
1994年 | 6篇 |
1993年 | 4篇 |
1992年 | 4篇 |
1991年 | 4篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1988年 | 5篇 |
1987年 | 6篇 |
1986年 | 5篇 |
1985年 | 2篇 |
1982年 | 1篇 |
1980年 | 3篇 |
1978年 | 2篇 |
1974年 | 1篇 |
排序方式: 共有1254条查询结果,搜索用时 10 毫秒
51.
Wu Bin Ying Da Som Moon Min Woo Lee Na Yeong Ko Nho Hoon Kwak Bumjae Lee Jin Zhu Ruoyu Zhang 《应用聚合物科学杂志》2018,135(5)
To simultaneously improve the fracture toughness and heat resistance of a cured toughened epoxy resin along with a reduction in its viscosity during the mixing process, two novel polysulfone‐type polymers are synthesized via azide–alkyne polymerization for use as toughening agents. The epoxy resin toughened with these polymers by in situ azide–alkyne polymerization during the cure process, which shows excellent processibility and based on the significantly lower viscosity (61 and 62 cP) during epoxy mixing process than that of commonly commercial polyethersulfone (PES, 127,612 cP). The novel polysulfone‐type polymer toughened epoxy resin showed the advantage in excellent fracture toughness than the PES toughened epoxy. In addition, the glass transition temperature of the novel polysulfone‐type polymer toughened epoxy resin is similar to that of the neat one (~230 °C) and does not decrease, which implies excellent heat resistance of the toughened epoxy. These phenomena can be attributed to the formation of semi‐interpenetrating polymer networks comprising the epoxy network and the linear polysulfone‐type polymers. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45790. 相似文献
52.
Counterweight optimization for reducing dynamic effects of clearance at a revolute joint 总被引:1,自引:0,他引:1
An optimal design formulation is developed to reduce undesirable dynamic effects due to clearance at a joint. The objective function to be minimized is the maximum ratio of the rate of change of the joint force direction (
) to the magnitude of the joint force (R), i.e. max (
) as calculated from the nominal mechanism without clearances. Design variables are the magnitude and the location of an added mass attached to each link.
Numerical examples for an offset slider crank mechanisms are considered. To check suitability of the objective function, the initial and optimized systems are simulated dynamically by integrating the system model equations and the phenomena of contact loss compared. It is found that although max ( ) is not a function of the magnitude of clearances and not of dimensionless form, it is a reasonable indicator of the contact loss phenomena for the single clearance system considered. The input torques have also been obtained and compared, shown to be more uniform in the optimized system. 相似文献
53.
Seongmi Ji Eun Sun Moon Han Byul Noh Hyun Jung Park Seongdae Kim Sung Oh Nagarajan Vinod Chang Won Choi Kilhan Kwak 《International journal of molecular sciences》2022,23(4)
Listeria monocytogenes (Lm) bacterial ghosts (LMGs) were produced by the minimum inhibitory concentration (MIC) of HCl, H2SO4, and NaOH. Acid and alkali effects on the LMGs were compared by in vitro and in vivo analyses. Scanning electron microscope showed that all chemicals form lysis pores on the Lm cell envelopes. Real-time qPCR revealed a complete absence of genomic DNA in HCl- and H2SO4-induced LMGs but not in NaOH-induced LMGs. HCl-, H2SO4- and NaOH-induced LMGs showed weaker or missing protein bands on SDS-PAGE gel when compared to wild-type Lm. Murine macrophages exposed to the HCl-induced LMGs showed higher cell viability than those exposed to NaOH-induced LMGs or wild-type Lm. The maximum level of cytokine expression (TNF-α, iNOS, IFN-γ, and IL-10 mRNA) was observed in the macrophages exposed to NaOH-induced LMGs, while that of IL-1β mRNA was observed in the macrophages exposed to HCl-induced LMGs. To investigate LMGs as a vaccine candidate, mice were divided into PBS buffer-injected, HCl- and NaOH-induced LMGs immunized groups. Mice vaccinated with HCl- and NOH-induced LMGs, respectively, significantly increased in specific IgG antibodies, bactericidal activities of serum, and CD4+ and CD8+ T-cell population. Antigenic Lm proteins reacted with antisera against HCl- and NOH-induced LMGs, respectively. Bacterial loads in HCl- and NaOH-induced LMGs immunized mice were significantly lower than PBS-injected mice after virulent Lm challenges. It suggested that vaccination with LMGs induces both humoral and cell-mediated immune responses and protects against virulent challenges. 相似文献
54.
55.
56.
Bharat Bhushan Kwang Joo Kwak Samit Gupta Stephen C Lee 《Journal of the Royal Society Interface》2009,6(37):719-733
Proteins on biomicroelectromechanical systems (BioMEMS) confer specific molecular functionalities. In planar FET sensors (field-effect transistors, a class of devices whose protein-sensing capabilities we demonstrated in physiological buffers), interfacial proteins are analyte receptors, determining sensor molecular recognition specificity. Receptors are bound to the FET through a polymeric interface, and gross disruption of interfaces that removes a large percentage of receptors or inactivates large fractions of them diminishes sensor sensitivity. Sensitivity is also determined by the distance between the bound analyte and the semiconductor. Consequently, differential properties of surface polymers are design parameters for FET sensors. We compare thickness, surface roughness, adhesion, friction and wear properties of silane polymer layers bound to oxides (SiO2 and Al2O3, as on AlGaN HFETs). We compare those properties of the film–substrate pairs after an additional deposition of biotin and streptavidin. Adhesion between protein and device and interfacial friction properties affect FET reliability because these parameters affect wear resistance of interfaces to abrasive insult in vivo. Adhesion/friction determines the extent of stickage between the interface and tissue and interfacial resistance to mechanical damage. We document systematic, consistent differences in thickness and wear resistance of silane films that can be correlated with film chemistry and deposition procedures, providing guidance for rational interfacial design for planar AlGaN HFET sensors. 相似文献
57.
Byung-Man Kwak Ji Eun Lee Jang-Hyuk Ahn Tae-Hong Jeon 《Journal of food engineering》2009,92(3):324-330
A laser diffraction particle sizing method involving wet analysis could be adapted effectively to measure the accurate particle size distribution of a spray-dried infant formula. Polar, polar aprotic and non-polar solvents, such as ethanol, methanol, acetone, pentane, heptane and hexane, were tested as dispersants for wet analysis. Non-polar solvents such as pentane, heptane and hexane found to be suitable dispersant because the shape of the infant formula particles in non-polar solvents was similar before and after the measurement while the particles had dissolved in the other solvents. The particle size distributions (PSD) of the infant formula determined by laser diffraction (Malvern Master Sizer, UK) using the dry analysis method with air was unsuitable because some parts of the primary and aggregated infant formula particles had been destroyed. The PSD graph of the air dispersion was shifted toward a smaller particle size from that of hexane dispersion. Overall, it is believed that laser diffraction particle sizing involving wet analysis with non-polar solvents may provide a suitable particle sizing method for infant formula products that is better than an air dispersion method. 相似文献
58.
Eun Ho Kim Kyung Hak Hyun Soo Hyun Kim Yoon Keun Kwak 《Mechatronics, IEEE/ASME Transactions on》2009,14(3):317-325
Emotion recognition is one of the latest challenges in human-robot interaction. This paper describes the realization of emotional interaction for a Thinking Robot, focusing on speech emotion recognition. In general, speaker-independent systems show a lower accuracy rate compared with speaker-dependent systems, as emotional feature values depend on the speaker and their gender. However, speaker-independent systems are required for commercial applications. In this paper, a novel speaker-independent feature, the ratio of a spectral flatness measure to a spectral center (RSS), with a small variation in speakers when constructing a speaker-independent system is proposed. Gender and emotion are hierarchically classified by using the proposed feature (RSS), pitch, energy, and the mel frequency cepstral coefficients. An average recognition rate of 57.2% (plusmn 5.7%) at a 90% confidence interval is achieved with the proposed system in the speaker-independent mode. 相似文献
59.
Siyoung Yang Seung Jun Choi Jungki Kwak Kihyun Kim Minjae Seo Tae Wha Moon Yin-Won Lee 《Food science and biotechnology》2013,22(2):425-432
Forty-seven strains of Aspergillus oryzae isolates from Korean nuruks were compared for their brewing characteristics. A. oryzae YI-A6 and YI-A7 showed the highest acid α-amylase, glucoamylase, and carboxypeptidase activities, respectively. Sixteen isolates with high amylolytic or proteolytic enzyme activities were selected for investigation of their rice wine fermentation characteristics. After 12 days of brewing at 15°C, ethanol concentrations were 10.2–14.3% for A. oryzae strains. Fermentation rates were the highest for YI-A7. Most rice wine samples fermented with nuruk strains had lower concentrations of off-flavor compounds than the control did. All mean sensory attribute values significantly differed among samples. Pearson correlation coefficients showed that glucoamylase activity was positively correlated to both ethanol productivity and overall harmony (p<0.01). Thus, glucoamylase activity was identified as the best factor for screening Aspergillus strains for use in rice wine brewing. 相似文献
60.
Sang Yong Shin Hackcheol Lee Seung Youb Han Chang-Hyo Seo Kayoung Choi Sunghak Lee Nack J. Kim Jai-Hyun Kwak Kwang-Geun Chin 《Metallurgical and Materials Transactions A》2010,41(1):138-148
An investigation was conducted into the correlation of microstructure and the cracking phenomenon that often occurred in hot-rolled
lightweight steel plates. Two kinds of steels were fabricated with varying Mn and Al contents, and their microstructures,
tensile properties, and high-temperature transformation behavior were investigated. In the two steels, banded structures containing
ferrite grains and κ-carbides were well developed along the rolling direction. Detailed microstructural analyses showed that cracks initiated
at film-type κ-carbides continuously formed interfaces between bands, while the band populated with κ-carbides did not play an important role in initiating cracks. Thus, the formation of band structures and film-type interfacial
κ-carbides must be minimized to prevent the cracking. The decreased content of hardenability elements, including aluminum,
higher finish-rolling temperature, reduced central segregation during the slabmaking process, and decreased material variation
during hot rolling, were suggested as practical methods for preventing the cracking. 相似文献