全文获取类型
收费全文 | 6686篇 |
免费 | 450篇 |
国内免费 | 18篇 |
专业分类
电工技术 | 129篇 |
综合类 | 9篇 |
化学工业 | 1467篇 |
金属工艺 | 244篇 |
机械仪表 | 409篇 |
建筑科学 | 128篇 |
矿业工程 | 2篇 |
能源动力 | 235篇 |
轻工业 | 637篇 |
水利工程 | 22篇 |
石油天然气 | 6篇 |
无线电 | 1153篇 |
一般工业技术 | 1415篇 |
冶金工业 | 416篇 |
原子能技术 | 71篇 |
自动化技术 | 811篇 |
出版年
2024年 | 7篇 |
2023年 | 86篇 |
2022年 | 127篇 |
2021年 | 220篇 |
2020年 | 157篇 |
2019年 | 182篇 |
2018年 | 220篇 |
2017年 | 217篇 |
2016年 | 251篇 |
2015年 | 229篇 |
2014年 | 323篇 |
2013年 | 436篇 |
2012年 | 445篇 |
2011年 | 528篇 |
2010年 | 348篇 |
2009年 | 395篇 |
2008年 | 347篇 |
2007年 | 265篇 |
2006年 | 280篇 |
2005年 | 227篇 |
2004年 | 209篇 |
2003年 | 183篇 |
2002年 | 178篇 |
2001年 | 147篇 |
2000年 | 124篇 |
1999年 | 128篇 |
1998年 | 205篇 |
1997年 | 139篇 |
1996年 | 78篇 |
1995年 | 83篇 |
1994年 | 67篇 |
1993年 | 60篇 |
1992年 | 45篇 |
1991年 | 37篇 |
1990年 | 30篇 |
1989年 | 23篇 |
1988年 | 10篇 |
1987年 | 17篇 |
1986年 | 16篇 |
1985年 | 12篇 |
1984年 | 15篇 |
1983年 | 10篇 |
1982年 | 4篇 |
1981年 | 3篇 |
1980年 | 5篇 |
1979年 | 7篇 |
1978年 | 3篇 |
1977年 | 5篇 |
1976年 | 10篇 |
1975年 | 4篇 |
排序方式: 共有7154条查询结果,搜索用时 15 毫秒
921.
Jihun Kim Jun Sung Jang Seung Wook Shin Hyeonghun Park Woo-Lim Jeong Seung-Hyun Mun Jung-Hong Min Jiyoung Ma Jaeyeong Heo Dong Seon Lee Jung-Je Woo Jin Hyeok Kim Hyeong-Jin Kim 《Small (Weinheim an der Bergstrasse, Germany)》2023,19(22):2370156
Herein, a novel combination of Mg- and Ga-co-doped ZnO (MGZO)/Li-doped graphene oxide (LGO) transparent electrode (TE)/electron-transporting layer (ETL) has been applied for the first time in Cu2ZnSn(S,Se)4 (CZTSSe) thin-film solar cells (TFSCs). MGZO has a wide optical spectrum with high transmittance compared to that with conventional Al-doped ZnO (AZO), enabling additional photon harvesting, and has a low electrical resistance that increases electron collection rate. These excellent optoelectronic properties significantly improved the short-circuit current density and fill factor of the TFSCs. Additionally, the solution-processable alternative LGO ETL prevented plasma-induced damage to chemical bath deposited cadmium sulfide (CdS) buffer, thereby enabling the maintenance of high-quality junctions using a thin CdS buffer layer (≈30 nm). Interfacial engineering with LGO improved the Voc of the CZTSSe TFSCs from 466 to 502 mV. Furthermore, the tunable work function obtained through Li doping generated a more favorable band offset in CdS/LGO/MGZO interfaces, thereby, improving the electron collection. The MGZO/LGO TE/ETL combination achieved a power conversion efficiency of 10.67%, which is considerably higher than that of conventional AZO/intrinsic ZnO (8.33%). 相似文献
922.
Da Luo Meihui Wang Yunqing Li Changsik Kim Ka Man Yu Yohan Kim Huijun Han Mandakini Biswal Ming Huang Youngwoo Kwon Min Goo Dulce C. Camacho‐Mojica Haofei Shi Won Jong Yoo Michael S. Altman Hyung‐Joon Shin Rodney S. Ruoff 《Advanced materials (Deerfield Beach, Fla.)》2019,31(35)
To date, thousands of publications have reported chemical vapor deposition growth of “single layer” graphene, but none of them has described truly single layer graphene over large area because a fraction of the area has adlayers. It is found that the amount of subsurface carbon (leading to additional nuclei) in Cu foils directly correlates with the extent of adlayer growth. Annealing in hydrogen gas atmosphere depletes the subsurface carbon in the Cu foil. Adlayer‐free single crystal and polycrystalline single layer graphene films are grown on Cu(111) and polycrystalline Cu foils containing no subsurface carbon, respectively. This single crystal graphene contains parallel, centimeter‐long ≈100 nm wide “folds,” separated by 20 to 50 µm, while folds (and wrinkles) are distributed quasi‐randomly in the polycrystalline graphene film. High‐performance field‐effect transistors are readily fabricated in the large regions between adjacent parallel folds in the adlayer‐free single crystal graphene film. 相似文献
923.
Y Namkung SM Smith SB Lee NV Skrypnyk HL Kim H Chin RH Scheller RW Tsien HS Shin 《Canadian Metallurgical Quarterly》1998,95(20):12010-12015
In comparison to the well characterized role of the principal subunit of voltage-gated Ca2+ channels, the pore-forming, antagonist-binding alpha1 subunit, considerably less is understood about how beta subunits contribute to neuronal Ca2+ channel function. We studied the role of the Ca2+ channel beta3 subunit, the major Ca2+ channel beta subunit in neurons, by using a gene-targeting strategy. The beta3 deficient (beta3-/-) animals were indistinguishable from the wild type (wt) with no gross morphological or histological differences. However, in sympathetic beta3-/- neurons, the L- and N-type current was significantly reduced relative to wt. Voltage-dependent activation of P/Q-type Ca2+ channels was described by two Boltzmann components with different voltage dependence, analogous to the "reluctant" and "willing" states reported for N-type channels. The absence of the beta3 subunit was associated with a hyperpolarizing shift of the "reluctant" component of activation. Norepinephrine inhibited wt and beta3-/- neurons similarly but the voltage sensitive component was greater for N-type than P/Q-type Ca2+ channels. The reduction in the expression of N-type Ca2+ channels in the beta3-/- mice may be expected to impair Ca2+ entry and therefore synaptic transmission in these animals. This effect may be reversed, at least in part, by the increase in the proportion of P/Q channels activated at less depolarized voltage levels. 相似文献
924.
Kun Yin Hung‐Yuan Lin Shin‐Tson Wu 《Journal of the Society for Information Display》2020,28(4):368-374
We demonstrate a reflective chirped polarization volume grating as a strong contender for wide field‐of‐view augmented reality display systems. By introducing gradient pitch along the beam propagation direction, the angular bandwidth extends dramatically from 18° to 54° while keeping over 80% average efficiency and 95% peak efficiency. 相似文献
925.
Shin Jungpil Islam Md Rashedul Rahim Md Abdur Mun Hyung-Jin 《Peer-to-Peer Networking and Applications》2020,13(2):635-646
Peer-to-Peer Networking and Applications - User authentication has become an essential security element that enables a wide range of applications in P2P systems for higher security and safety... 相似文献
926.
Zhang Lelin Wang Zhiyong Yao Tingting Staoh Shin’ichi Mei Tao Feng David Dagan 《Multimedia Tools and Applications》2018,77(2):2057-2081
Multimedia Tools and Applications - Retrieving videos with similar actions is an important task with many applications. Yet it is very challenging due to large variations across different videos.... 相似文献
927.
Junaid ur Rehman Ahmad Farooq Youngmin Jeong Hyundong Shin 《Quantum Information Processing》2018,17(10):271
We address the problem of unambiguous discrimination of quantum channels (UDQC) without entanglement. As our main result, we show that even in the absence of entanglement, partial UDQC (PUDQC) can still be performed—depending on the unknown given channel. We provide a necessary and sufficient condition for PUDQC and put forth a method to perform the PUDQC once the said condition is met. We propose the performance metrics that capture the expected performance of the PUDQC independent of the specific channels to be distinguished. Finally, we perform PUDQC on several qubit channel pairs as concrete examples and derive the proposed performance metrics for these channel pairs. 相似文献
928.
Soyeon Koo Seungkeun Kim Jinyoung Suk Youdan Kim Jongho Shin 《International Journal of Control, Automation and Systems》2018,16(6):2697-2708
This paper investigates automatic UAV carrier landing using model predictive control that considers carrier deck motions. With dynamic models of a medium-altitude, long-endurance UAV and an aircraft carrier, the proposed guidance and control approach takes the relative geometry between the UAV and the carrier deck into account for safer shipboard landings. Automatic carrier landing is performed sequentially by two types of control systems. A linear quadratic regulator with an integral term is applied up to a few seconds before touchdown followed by a model predictive controller. At this time, optimal control input sequences over a certain time horizon are calculated in real time by predicting the motions of the carrier deck and the UAV. Numerical simulations are performed for a UAV and a carrier with heave motion to verify the feasibility of the proposed approach. 相似文献
929.
Globalization has increased the volatility of international financial transactions, particularly those related to international stock markets. An increase in the volatility of one country's stock market spreads throughout the globe, affecting other countries' stock markets. In particular, the Dow Jones Industrial Average plays an extremely important role in the international stock market. This paper uses the generally weighted moving average method and data from the Dow Jones Industrial Average, the National Association of Securities Dealers Automated Quotations, Japan's Nikkei 225, the Korea Composite Stock Price Index, and the Hong Kong Hang Seng Index to predict the performance of the Taiwan Capitalization Weighted Stock Index. This paper attempts to find the smallest prediction error using the optimal combination of generally weighted moving average model parameters and combinations of various international stock market data and compares the results to that found using the exponentially weighted moving average model to explore differences between the two types of forecasting models. 相似文献
930.
Kyungwoo Kang Myungjae Kwak Seung Kyoon Shin 《Journal of Computer Information Systems》2018,58(2):110-121
This study investigates the underlying motivational factors of knowledge exchange intentions (intention to obtain and to provide knowledge) within virtual community contexts. Perceived virtual network structures, namely virtual network connectivity (CN) and virtual network closeness (CL), are suggested as the important antecedents of knowledge sharing intentions in the context of virtual knowledge exchange communities. Anonymity (AN), one of the unique characteristics of virtual communities, but controversial due to its multi-faceted effects, is considered in a structural model as a factor having an impact on a virtual network structure. Data collected from participants of virtual communities through online surveys are analyzed using Partial Least Squares (PLS) structural equation modeling (SEM) to empirically test the proposed hypotheses. The results reveal that both CN and CL have a significant impact on both of the knowledge exchange intentions although CL shows an opposite direction of the impact. The results also show that AN has a significant impact on CL as expected but not on CN. Implications of this study may shed some light on better understanding community participants’ intentions to obtain and provide knowledge, along with the impact of anonymity on the perceived network structure. 相似文献