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   98篇
  免费   29篇
电工技术   1篇
化学工业   26篇
机械仪表   4篇
轻工业   17篇
无线电   31篇
一般工业技术   39篇
冶金工业   3篇
自动化技术   6篇
  2023年   3篇
  2022年   2篇
  2021年   8篇
  2020年   5篇
  2019年   5篇
  2018年   6篇
  2017年   10篇
  2016年   10篇
  2015年   7篇
  2014年   14篇
  2013年   8篇
  2012年   8篇
  2011年   7篇
  2010年   3篇
  2009年   3篇
  2008年   2篇
  2007年   2篇
  2006年   5篇
  2005年   1篇
  2004年   3篇
  2002年   1篇
  2000年   3篇
  1999年   2篇
  1998年   1篇
  1997年   1篇
  1996年   3篇
  1994年   2篇
  1993年   1篇
  1992年   1篇
排序方式: 共有127条查询结果,搜索用时 9 毫秒
31.
Rechargeable batteries with a Li metal anode and Ni‐rich Li[NixCoyMn1?x?y]O2 cathode (Li/Ni‐rich NCM battery) have been emerging as promising energy storage devices because of their high‐energy density. However, Li/Ni‐rich NCM batteries have been plagued by the issue of the thermodynamic instability of the Li metal anode and aggressive surface chemistry of the Ni‐rich cathode against electrolyte solution. In this study, a bi‐functional additive, adiponitrile (C6H8N2), is proposed which can effectively stabilize both the Li metal anode and Ni‐rich NCM cathode interfaces. In the Li/Ni‐rich NCM battery, the addition of 1 wt% adiponitrile in 0.8 m LiTFSI + 0.2 M LiDFOB + 0.05 M LiPF6 dissolved in EMC/FEC = 3:1 electrolyte helps to produce a conductive and robust Li anode/electrolyte interface, while strong coordination between Ni4+ on the delithiated Ni‐rich cathode and nitrile group in adiponitrile reduces parasitic reactions between the electrolyte and Ni‐rich cathode surface. Therefore, upon using 1 wt% adiponitrile, the Li/full concentration gradient Li[Ni0.73Co0.10Mn0.15Al0.02]O2 battery achieves an unprecedented cycle retention of 75% over 830 cycles under high‐capacity loading of 1.8 mAh cm?2 and fast charge–discharge time of 2 h. This work marks an important step in the development of high‐performance Li/Ni‐rich NCM batteries with efficient electrolyte additives.  相似文献   
32.
The introduction of Ti atoms by means of TiCl4 treatment and hydrothermal synthesis has been applied to mordenite zeolite with different structures from silicalite. The incorporation of Ti into the mordenite framework is demonstrated by XRD, FTIR,29Si MAS NMR techniques, and tested with catalytic oxidation reactions. Ti-Al-mordenite catalyses the oxidation ofn-hexane, cyclohexane and benzene with hydrogen peroxide under very mild conditions. These reactions can be performed in methanol, acetonitrile and water as solvents. The rate of the reaction is strongly affected by the kind of solvent.  相似文献   
33.
34.
This study evaluated the susceptibility effects using quantitative susceptibility mapping (QSM) as a marker for regional brain iron alternations in diabetic rat brains. Otsuka Long‐Evans Tokushima Fatty (OLETF) rats (n = 7) and age‐matched lean Long‐Evans Tokushima Otsuka (LETO) control rats (n = 8) were scanned using a three‐dimensional gradient‐echo sequence in a 3 Tesla MRI to map QSM. The correlation analysis was performed to evaluate the relationship between the QSM value and the body weight and the fasting blood glucose value of the rats. QSM values in the OLETF group were significantly increased in hippocampi and thalami, as compared with those of the LETO group. The QSM values of the OLETF rats were negatively correlated with the body weight in putamen and were significantly correlated with the fasting blood glucose level in the left amygdala and right thalamus. With higher QSM values in diabetic rats than in control rats, QSM values in the diabetic group were significantly correlated with the body weight and the fasting blood glucose level, indicating that the QSM technique should be helpful to noninvasively investigate iron overload in the diabetic brain.  相似文献   
35.
36.
Additional surgeries for implantable biomedical devices are inevitable to replace discharged batteries, but repeated surgeries can be a risk to patients, causing bleeding, inflammation, and infection. Therefore, developing self‐powered implantable devices is essential to reduce the patient's physical/psychological pain and financial burden. Although wireless communication plays a critical role in implantable biomedical devices that contain the function of data transmitting, it has never been integrated with in vivo piezoelectric self‐powered system due to its high‐level power consumption (microwatt‐scale). Here, wireless communication, which is essential for a ubiquitous healthcare system, is successfully driven with in vivo energy harvesting enabled by high‐performance single‐crystalline (1 ? x )Pb(Mg1/3Nb2/3)O3?(x )Pb(Zr,Ti)O3 (PMN‐PZT). The PMN‐PZT energy harvester generates an open‐circuit voltage of 17.8 V and a short‐circuit current of 1.74 µA from porcine heartbeats, which are greater by a factor of 4.45 and 17.5 than those of previously reported in vivo piezoelectric energy harvesting. The energy harvester exhibits excellent biocompatibility, which implies the possibility for applying the device to biomedical applications.  相似文献   
37.
An energy dispersive X-ray fluorescence (ED-XRF) spectrometer and a near infrared (NIR) spectrometer combined with chemometrics were applied for origin discrimination of 48 Korean, 44 Chinese, and 21 Indian sesame seed samples used for development of a discriminant calibration model. Multi-elemental ED-XRF analysis based on Mg, Al, Si, P, S, Cl, K, Ca, Mn, Fe, and Cu was used for comparisons among origins. All elements, except for Fe, showed differences and 96.5% of seed samples were assigned to the correct origin using discriminant analysis based on chemical analytical results. NIR measurements were performed for spectral scanning. Classification of seeds using NIR discriminant analysis achieved 89.4% of seed samples assigned to the correct origin. Both ED-XRF and NIR are useful as nondestructive tools for discrimination of sesame seed origins.  相似文献   
38.
In this paper, we propose a novel equalization on‐channel repeater (OCR) with a feedback interference canceller (FIC) to relay terrestrial digital multimedia broadcasting signals in single frequency networks. The proposed OCR not only has high output power by cancelling the feedback signals caused by insufficient antenna isolation through the FIC, but also shows better output signal quality than the conventional OCR by removing multipath signals existing between the main transmitter and the OCR through an equalizer. In addition, computer simulations and laboratory test results demonstrate that the proposed OCR successfully cancels feedback signals and compensates channel distortions and provides a higher quality transmitting signal with higher output power than conventional OCRs.  相似文献   
39.
1D perovskite materials are of significant interest to build a new class of nanostructures for electronic and optoelectronic applications. However, the study of colloidal perovskite nanowires (PNWs) lags far behind those of other established perovskite materials such as perovskite quantum dots and perovskite thin films. Herein, a dual-phase passivation strategy to synthesize all-inorganic PNWs with minimized surface defects is reported. The local phase transition from CsPbBr3 to CsPb2Br5 in PNWs increases the photoluminescence quantum yield, carrier lifetime, and water-resistivity, owing to the energetic and chemical passivation effect. In addition, these dual-phase PNWs are employed as an interfacial layer in perovskite solar cells (PSCs). The enhanced surface passivation results in an efficient carrier transfer in PSCs, which is a critical enabler to increase the power conversion efficiency (PCE) to 22.87%, while the device without PNWs exhibits a PCE of 20.74%. The proposed strategy provides a surface passivation platform in 1D perovskites, which can lead to the development of novel nanostructures for future optoelectronic devices.  相似文献   
40.
Plants rely on multiple immune systems to protect themselves from pathogens. When pattern-triggered immunity (PTI)—the first layer of the immune response—is no longer effective as a result of pathogenic effectors, effector-triggered immunity (ETI) often provides resistance. In ETI, host plants directly or indirectly perceive pathogen effectors via resistance proteins and launch a more robust and rapid defense response. Resistance proteins are typically found in the form of nucleotide-binding and leucine-rich-repeat-containing receptors (NLRs). Upon effector recognition, an NLR undergoes structural change and associates with other NLRs. The dimerization or oligomerization of NLRs signals to downstream components, activates “helper” NLRs, and culminates in the ETI response. Originally, PTI was thought to contribute little to ETI. However, most recent studies revealed crosstalk and cooperation between ETI and PTI. Here, we summarize recent advancements in our understanding of the ETI response and its components, as well as how these components cooperate in the innate immune signaling pathways. Based on up-to-date accumulated knowledge, this review provides our current perspective of potential engineering strategies for crop protection.  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