全文获取类型
收费全文 | 214396篇 |
免费 | 16078篇 |
国内免费 | 7803篇 |
专业分类
电工技术 | 11342篇 |
技术理论 | 14篇 |
综合类 | 11222篇 |
化学工业 | 37750篇 |
金属工艺 | 10791篇 |
机械仪表 | 12163篇 |
建筑科学 | 16746篇 |
矿业工程 | 4970篇 |
能源动力 | 6055篇 |
轻工业 | 13453篇 |
水利工程 | 3322篇 |
石油天然气 | 11110篇 |
武器工业 | 1347篇 |
无线电 | 26114篇 |
一般工业技术 | 28369篇 |
冶金工业 | 12856篇 |
原子能技术 | 2176篇 |
自动化技术 | 28477篇 |
出版年
2024年 | 886篇 |
2023年 | 3323篇 |
2022年 | 5933篇 |
2021年 | 8081篇 |
2020年 | 5934篇 |
2019年 | 5135篇 |
2018年 | 5594篇 |
2017年 | 6360篇 |
2016年 | 5872篇 |
2015年 | 7424篇 |
2014年 | 9742篇 |
2013年 | 12763篇 |
2012年 | 12608篇 |
2011年 | 14361篇 |
2010年 | 11927篇 |
2009年 | 11812篇 |
2008年 | 11293篇 |
2007年 | 10887篇 |
2006年 | 11188篇 |
2005年 | 9934篇 |
2004年 | 6840篇 |
2003年 | 6017篇 |
2002年 | 5510篇 |
2001年 | 4840篇 |
2000年 | 4994篇 |
1999年 | 5767篇 |
1998年 | 5441篇 |
1997年 | 4495篇 |
1996年 | 4110篇 |
1995年 | 3448篇 |
1994年 | 2907篇 |
1993年 | 2343篇 |
1992年 | 1816篇 |
1991年 | 1383篇 |
1990年 | 1149篇 |
1989年 | 982篇 |
1988年 | 760篇 |
1987年 | 624篇 |
1986年 | 491篇 |
1985年 | 461篇 |
1984年 | 336篇 |
1983年 | 329篇 |
1982年 | 267篇 |
1981年 | 238篇 |
1980年 | 207篇 |
1979年 | 171篇 |
1978年 | 155篇 |
1977年 | 134篇 |
1976年 | 150篇 |
1975年 | 116篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
Yin-Feng Wang Meng Li Jin-Ming Teng He-Ye Zhou Chuan-Feng Chen 《Advanced functional materials》2021,31(49):2106418
Recently, circularly polarized organic light-emitting diodes (CP-OLEDs) fabricated with thermally activated delayed fluorescence (TADF) emitters are developed rapidly. However, most devices are fabricated by vacuum deposition technology, and developing efficient solution-processed CP-OLEDs, especially nondoped devices, is still a challenge. Herein, a pair of triptycene-based enantiomers, (S,S)-/(R,R)-TpAc-TRZ, are synthesized. The novel chiral triptycene scaffold of enantiomers avoids their intermolecular π–π stacking, which is conducive to their aggregation-induced emission characteristics and high photoluminescence quantum yield of 85% in the solid state. Moreover, the triptycene-based enantiomers exhibit efficient TADF activities with a small singlet-triplet energy gap (ΔEST) of 0.03 eV and delayed fluorescence lifetime of 1.1 µs, as well as intense circularly polarized luminescence with dissymmetry factors (|gPL|) of about 1.9 × 10−3. The solution-processed nondoped CP-OLEDs based on (S,S)-/(R,R)-TpAc-TRZ not only display obvious circularly polarized electroluminescence signals with gEL values of +1.5 × 10−3 and −2.0 × 10−3, respectively, but also achieve high efficiencies with external quantum, current, and power efficiency up to 25.5%, 88.6 cd A−1, and 95.9 lm W−1, respectively. 相似文献
12.
Wireless Networks - TCP latency is critical to the performance of Web services. However, packet loss greatly impairs the TCP performance due to its poor loss recovery mechanisms. Recent work FUSO... 相似文献
13.
Nitsa Buaron Antonella Mangraviti Francesco Volpin Ann Liu Mariangela Pedone Eric Sankey Dina Aranovich Itay Adar Fausto J. Rodriguez Abraham Nyska Riki Goldbart Tamar Traitel Henry Brem Betty Tyler Joseph Kost 《Advanced functional materials》2021,31(44):2100643
Treating neuroinflammation-related injuries and disorders through manipulation of neuroinflammation functions is being heralded as a new therapeutic strategy. In this study, a novel pectic galactan (PG) polysaccharide based gene therapy approach is developed for targeting reactive gliosis in neuroinflammation. Galectin-3 (Gal-3) is a cell protein with a high affinity to β-galactoside sugars and is highly expressed in reactive gliosis. Since PG carries galactans, it can target reactive gliosis via specific carbohydrate interaction between galactan and Gal-3 on the cell membrane, and therefore can be utilized as a carrier for delivering genes to these cells. The carrier is synthesized by modifying quaternary ammonium groups on the PG. The resulting quaternized PG (QPG) is found to form complexes with plasmid DNA with a mean diameter of 100 nm and have the characteristics required for targeted gene therapy. The complexes efficiently condense large amounts of plasmid per particle and successfully bind to Gal-3. The in vivo study shows that the complexes are biocompatible and safe for administration and can selectively transfect reactive glial cells of an induced cortical lesion. The results confirm that this PG-based delivery system is a promising platform for targeting Gal-3 overexpressing neuroinflammation cells for treating neuroinflammation-related injuries and neurodegenerative diseases. 相似文献
14.
Amino acid modified polyaspartic acids were evaluated as calcium-scale inhibitors. Feasibility of scale inhibition experiments was analyzed by molecular dynamics simulation and Gaussian optimization, and the scale inhibition mechanism was theoretically analyzed. Scale inhibition performance was studied by scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, static scale inhibition experiments, and electrochemical performance testing, which provided an experimental basis for the molecular dynamics simulation. The experimental results showed that Arg-SA-PASP has better scale inhibition and corrosion inhibition performance than His-SA-PASP. The scale inhibition effect increased with increasing concentration. Electrochemical tests indicated that Arg-SA-PASP is an excellent scale and corrosion inhibitor. 相似文献
15.
Fluorescence‐Activated Cell Sorters: Standing Surface Acoustic Wave (SSAW)‐Based Fluorescence‐Activated Cell Sorter (Small 40/2018)
下载免费PDF全文
![点击此处可从《Small (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
16.
Xueye Chen Yue Tian 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2020,95(3):806-812
Since the beginning of the 21st Century, the development of microfluidic chip technology has been very rapid and has attracted the attention of more and more scholars. As an important part of the microfluidic chip, the performance of the micromixer is critical. The fractal structure in the microchannels helps to improve the mixing performance of the micromixer and improve the mixing efficiency of the micromixer. The research results of other scholars are of great significance to the research of the present paper, which mainly studies the effect of changing the baffle state on the mixing efficiency of the micromixer based on the Koch fractal principle. Through simulation analysis, it was found that the mixing efficiency of the baffles distributed on both sides of the microchannel was higher than the mixing efficiency of the baffles distributed on the microchannel side. When the distance between adjacent baffles was divided into 0.15, 0.25 and 0.35 mm, simulated data suggested that the baffle distance of 0.15 mm was best. Increasing the number of baffles from six to eight groups increased the mixing path of the fluid in the microchannel and improved mixing efficiency. A comparison of mixing efficiencies of the 0°, 15° and 30° baffle angles revealed that very significant improvement in mixing efficiency was obtained at 30°. © 2019 Society of Chemical Industry 相似文献
17.
World Wide Web - Infectious diseases such as Influenza and Ebola pose a serious threat to everyone but certain demographics and cohorts face a higher risk of infection than others. This research... 相似文献
18.
Wesley P. Chan Hiroto Mizohana Xiangyu Chen Yasuto Shiigi Yoshiyuki Yamanoue Masaki Nagatsuka Masayuki Inaba 《野外机器人技术杂志》2019,36(1):17-33
The use of field robots can greatly decrease the amount of time, effort, and associated risk compared to if human workers were to carryout certain tasks such as disaster response. However, transportability and reliability remain two main issues for most current robot systems. To address the issue of transportability, we have developed a lightweight modularizable platform named AeroArm. To address the issue of reliability, we utilize a multimodal sensing approach, combining the use of multiple sensors and sensor types, and the use of different detection algorithms, as well as active continuous closed‐loop feedback to accurately estimate the state of the robot with respect to the environment. We used Challenge 2 of the 2017 Mohammed Bin Zayed International Robotics Competition as an example outdoor manipulation task, demonstrating the capabilities of our robot system and approach in achieving reliable performance in the fields, and ranked fifth place internationally in the competition. 相似文献
19.
World Wide Web - The wide spread use of positioning and photographing devices gives rise to a deluge of traffic trajectory data (e.g., vehicle passage records and taxi trajectory data), with each... 相似文献
20.