全文获取类型
收费全文 | 2103篇 |
免费 | 177篇 |
国内免费 | 9篇 |
专业分类
电工技术 | 42篇 |
综合类 | 4篇 |
化学工业 | 504篇 |
金属工艺 | 78篇 |
机械仪表 | 126篇 |
建筑科学 | 44篇 |
矿业工程 | 1篇 |
能源动力 | 96篇 |
轻工业 | 190篇 |
水利工程 | 7篇 |
石油天然气 | 8篇 |
无线电 | 453篇 |
一般工业技术 | 474篇 |
冶金工业 | 68篇 |
原子能技术 | 15篇 |
自动化技术 | 179篇 |
出版年
2024年 | 6篇 |
2023年 | 40篇 |
2022年 | 69篇 |
2021年 | 97篇 |
2020年 | 50篇 |
2019年 | 62篇 |
2018年 | 87篇 |
2017年 | 85篇 |
2016年 | 104篇 |
2015年 | 87篇 |
2014年 | 90篇 |
2013年 | 167篇 |
2012年 | 169篇 |
2011年 | 206篇 |
2010年 | 136篇 |
2009年 | 129篇 |
2008年 | 115篇 |
2007年 | 72篇 |
2006年 | 58篇 |
2005年 | 56篇 |
2004年 | 55篇 |
2003年 | 60篇 |
2002年 | 46篇 |
2001年 | 34篇 |
2000年 | 38篇 |
1999年 | 29篇 |
1998年 | 39篇 |
1997年 | 23篇 |
1996年 | 22篇 |
1995年 | 16篇 |
1994年 | 7篇 |
1993年 | 6篇 |
1992年 | 7篇 |
1991年 | 4篇 |
1990年 | 5篇 |
1989年 | 5篇 |
1987年 | 4篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1979年 | 1篇 |
1977年 | 1篇 |
排序方式: 共有2289条查询结果,搜索用时 15 毫秒
991.
Ultrafine particles and other hazardous materials are emitted during 3D printing, but the effect of temperature on such particles has not been studied systematically. The aim of this study was to evaluate the effect of temperature on the emission rate of particulate matter during fused deposition modeling (FDM) three-dimensional (3D) printing using different filament types. The number concentration of particles was measured with direct-reading instruments in an exposure chamber at various temperatures while using four filament materials during 3D printing. The temperature was increased from 185 to 290°C in 15°C increments, while incorporating the manufacturer-recommended operating conditions. The emission rate increased gradually as the temperature increased for all filament types, and temperature was the key factor affecting the emission rate after filament type. For all filaments, at the lowest operating temperature, the emission rate was 107-109 particles/min, whereas the emission rate at the highest temperature was about 1011 particles/min, that is, 100-10 000 times higher than the emission rate at the lowest temperature. To reduce particle emissions from 3D printing, we recommend printing at the lowest temperature possible or using low-emission materials. 相似文献
992.
Yongmin Jeon Hye‐Ryung Choi Kyoung‐Chan Park Kyung Cheol Choi 《Journal of the Society for Information Display》2020,28(4):324-332
Phototherapeutics is both safely noninvasive and can be employed to treat a variety of sites and diseases. Current rigid and bulky conventional light sources, such as LED or laser‐based phototherapy devices, are difficult to transport and use for regular irradiation treatments. To solve this problem, flexible organic light‐emitting diode (OLED) light sources are the best candidates, and if applied very thinly as a skin‐like platform, the ultimate attachable phototherapeutics can be realized. We demonstrated a very thin flexible OLED‐based photonic skin with a total thickness of 6 μm for application in attachable phototherapeutics. It was optimized by controlling the peak wavelengths (600–700 nm) and irradiation interval of the flexible OLED thus improving the regeneration effect of the artificial skin by up to 70%. In addition, when the flexible OLED‐based photonic skin was attached to a dressing film before being applied to the skin, it delivered the same electro‐optical properties, while protecting against external contamination. The OLED skin on the dressing film had an operating lifetime of more than 100 h. These results confirmed the applicability of flexible OLED‐based photonic skin to various light treatment areas, such as surgical wounds that require periodic irradiation. 相似文献
993.
994.
995.
Hyo-Rim Lee Sung-Chan Lee Dong Ha Lee Won-Sil Choi Chan-Sik Jung Jae-Ho Jeon Jeong-Eun Kim Il-Kwon Park 《Journal of chemical ecology》2017,43(7):670-678
In this study, we isolated and identified an aggregation-sex pheromone from Monochamus saltuarius, the major insect vector of the pine wood nematode in Korea. Adult males of M. saltuarius produce 2-undecyloxy-1-ethanol, which is known as an aggregation-sex pheromone in other Monochamus species. We performed field experiments to determine the attractiveness of the pheromone and other synergists. More M. saltuarius adult beetles were attracted to traps baited with the pheromone than to unbaited traps. Ethanol and (?)-α-pinene interacted synergistically with the pheromone. Traps baited with the pheromone + (?)-α-pinene +ethanol were more attractive to M. saltuarius adults than traps baited with the pheromone, (?)-α-pinene, or ethanol alone. Ipsenol, ipsdienol, and limonene were also identified as synergists of the aggregation-sex pheromone for M. saltuarius adults. In field experiments, the proportion of females was much higher in the beetles caught in traps than among the beetles emerging from naturally-infested logs in the laboratory. Our results suggest that a combination of aggregation-sex pheromone and synergists could be very effective for monitoring and managing M. saltuarius. 相似文献
996.
Thermal and catalytic degradation of waste high-density polyethylene (HDPE) using spent FCC catalyst
Kyong-Hwan?LeeEmail author Sang-Gu?Jeon Kwang-Ho?Kim Nam-Sun?Noh Dae-Hyun?Shin Jaehyeon?Park Younghwa?Seo Jurng-Jae?Yee Geug-Tae?Kim 《Korean Journal of Chemical Engineering》2003,20(4):693-697
Thermal and catalytic degradation using spent fluid catalytic cracking (FCC) catalyst of waste high-density polyethylene (HDPE)
at 430 °C into fuel oil were carried out with a stirred semi-batch operation. The product yield and the recovery amount, molecular
weight distribution and paraffin, olefin, naphthene and aromatic (PONA) distribution of liquid product by catalytic degradation
using spent FCC catalyst were compared with those by thermal degradation. The catalytic degradation had lower degradation
temperature, faster liquid product rate and more olefin products as well as shorter molecular weight distributions of gasoline
range in the liquid product than thermal degradation. These results confirmed that the catalytic degradation using spent FCC
catalyst could be a better alternative method to solve a major environmental problem of waste plastics.
This paper is dedicated to Dr. Youn Yong Lee on the occasion of his retirement from Korea Institute of Science and Technology. 相似文献
997.
Shin-Wook Jeon 《Electrochimica acta》2005,51(2):268-273
LiCoO2 thin films were deposited using radio frequency (rf) magnetron sputtering system on stainless steel substrates. Different rf powers, up to 150 W, were applied during deposition. The as-deposited films exhibited (1 0 1) and (1 0 4) preferred orientation and the nanocrystalline film structure was enhanced with increasing rf power. The film crystallinity was examined using X-ray diffraction, Raman scattering spectroscopy and transmission electron microscopy. The compositions of the films were determined by inductively coupled plasma-mass spectroscopy. The average discharge capacity of as-deposited films is about 59 μAh/(cm2 μm) for cut-off voltage range of 4.2 and 3.0 V. From the electrochemical cycling data, it is suggested that as-deposited LiCoO2 films with a nanocrystalline structure and a favorable preferred orientation, e.g. (1 0 1) or (1 0 4) texture, can be used without post-annealing at high temperatures for solid-state thin film batteries. 相似文献
998.
Young Tack Lee Pyo Jin Jeon Jae Hyun Han Jongtae Ahn Hyo Sun Lee June Yeong Lim Won Kook Choi Jin Dong Song Min‐Chul Park Seongil Im Do Kyung Hwang 《Advanced functional materials》2017,27(47)
2D layered van der Waals (vdW) atomic crystals are an emerging class of new materials that are receiving increasing attention owing to their unique properties. In particular, the dangling‐bond‐free surface of 2D materials enables integration of differently dimensioned materials into mixed‐dimensional vdW heterostructures. Such mixed‐dimensional heterostructures herald new opportunities for conducting fundamental nanoscience studies and developing nanoscale electronic/optoelectronic applications. This study presents a 1D ZnO nanowire (n‐type)–2D WSe2 nanosheet (p‐type) vdW heterojunction diode for photodetection and imaging process. After amorphous fluoropolymer passivation, the ZnO–WSe2 diode shows superior performance with a much‐enhanced rectification (ON/OFF) ratio of over 106 and an ideality factor of 3.4–3.6 due to the carbon–fluorine (C? F) dipole effect. This heterojunction device exhibits spectral photoresponses from ultraviolet (400 nm) to near infrared (950 nm). Furthermore, a prototype visible imager is demonstrated using the ZnO–WSe2 heterojunction diode as an imaging pixel. To the best of our knowledge, this is the first demonstration of an optoelectronic device based on a 1D–2D hybrid vdW heterojunction. This approach using a 1D ZnO–2D WSe2 heterojunction paves the way for the further development of electronic/optoelectronic applications using mixed‐dimensional vdW heterostructures. 相似文献
999.
Min-Kyeung Choi Minh Thong Le Hye-Sun Cho Juyoung Lee Hyoim Jeon Se-Yeoun Cha Manheum Na Taehoon Chun Jin-Hoi Kim Hyuk Song Chankyu Park 《International journal of molecular sciences》2021,22(4)
Antimicrobial peptides (AMPs) are of interest as alternatives to antibiotics or immunomodulators. We generated and characterized the phenotypes of transgenic mice overexpressing protegrin 1 (PG1), a potent porcine cathelicidin. No obvious differences were observed between PG1 transgenic and wild-type mice in terms of growth, development, general behaviour, and the major immune cell population. However, PG1 transgenic mice intranasally infected with Staphylococcus aureus resulted in a reduction in microscopic pulmonary injury, improved clearance of bacteria, and lower proinflammatory cytokine secretion, compared to those of wild-type mice. On the other hand, approximately 25% of PG1 transgenic mice (n = 54/215) showed corneal opacity and developed inflammation in the eye, resulting ultimately in phthisis bulbi. Immunohistochemical analyses revealed that PG1 and its activator, neutrophil elastase, localized to the basal cells of the cornea and glands in eyelids, respectively. In addition, apoptosis indicated by a Terminal deoxynucleotidyl transferase dUTP nick end labelling (TUNEL)-positive signal was detected from flat cells of the cornea. Our study suggests that the expression regulation or localization of AMPs such as PG1 is important to prevent their adverse effects. However, our results also showed that the cytotoxic effects of PG1 on cells could be tolerated in animals, except for the eyes. 相似文献
1000.
The main drawback of the use of transmission-type holographic screens is poor color reproduction caused by their high spectral dispersion. For overcoming this drawback, a long, narrow diffusing slit is used as an object when recording the screen. The necessary size and position of the slit relative to the photoplate and to the recording and reconstruction beams are determined by the phase relations of the beams. By use of the slit, holographic screens of 30 cm x 40 cm are recorded with a diverging reference beam and are used to display a multiview full-color stereoscopic image. The images displayed on the screen show no sign of color separation except near the edges of the screen. The image brightness on the screen is high enough that it can be watched in a normally illuminated room. 相似文献