全文获取类型
收费全文 | 2267篇 |
免费 | 62篇 |
国内免费 | 7篇 |
专业分类
电工技术 | 46篇 |
综合类 | 1篇 |
化学工业 | 359篇 |
金属工艺 | 46篇 |
机械仪表 | 52篇 |
建筑科学 | 40篇 |
矿业工程 | 1篇 |
能源动力 | 72篇 |
轻工业 | 67篇 |
水利工程 | 4篇 |
石油天然气 | 1篇 |
无线电 | 537篇 |
一般工业技术 | 500篇 |
冶金工业 | 169篇 |
原子能技术 | 16篇 |
自动化技术 | 425篇 |
出版年
2023年 | 11篇 |
2022年 | 32篇 |
2021年 | 40篇 |
2020年 | 24篇 |
2019年 | 30篇 |
2018年 | 37篇 |
2017年 | 29篇 |
2016年 | 49篇 |
2015年 | 35篇 |
2014年 | 73篇 |
2013年 | 196篇 |
2012年 | 128篇 |
2011年 | 139篇 |
2010年 | 110篇 |
2009年 | 110篇 |
2008年 | 148篇 |
2007年 | 93篇 |
2006年 | 87篇 |
2005年 | 82篇 |
2004年 | 77篇 |
2003年 | 72篇 |
2002年 | 60篇 |
2001年 | 59篇 |
2000年 | 51篇 |
1999年 | 63篇 |
1998年 | 84篇 |
1997年 | 61篇 |
1996年 | 69篇 |
1995年 | 34篇 |
1994年 | 38篇 |
1993年 | 29篇 |
1992年 | 21篇 |
1991年 | 23篇 |
1990年 | 17篇 |
1989年 | 14篇 |
1988年 | 12篇 |
1987年 | 7篇 |
1986年 | 10篇 |
1985年 | 10篇 |
1984年 | 10篇 |
1983年 | 7篇 |
1982年 | 9篇 |
1981年 | 3篇 |
1980年 | 4篇 |
1979年 | 5篇 |
1978年 | 3篇 |
1977年 | 6篇 |
1976年 | 6篇 |
1974年 | 3篇 |
1973年 | 3篇 |
排序方式: 共有2336条查询结果,搜索用时 0 毫秒
71.
Nitesh K. Gupta Srinivasan Jayakumar Wen-Chieh Huang Pieter Leyssen Johan Neyts Sergey O. Bachurin Jih Ru Hwu Shwu-Chen Tsay 《International journal of molecular sciences》2022,23(20)
The yellow fever virus (YFV) is an emerging RNA virus and has caused large outbreaks in Africa and Central and South America. The virus is often transmitted through infected mosquitoes and spreads from area to area because of international travel. Being an acute viral hemorrhagic disease, yellow fever can be prevented by an effective, safe, and reliable vaccine, but not be eliminated. Currently, there is no antiviral drug available for its cure. Thus, two series of novel bis(benzofuran–1,3-imidazolidin-4-one)s and bis(benzofuran–1,3-benzimidazole)s were designed and synthesized for the development of anti-YFV lead candidates. Among 23 new bis-conjugated compounds, 4 of them inhibited YFV strain 17D (Stamaril) on Huh-7 cells in the cytopathic effect reduction assays. These conjugates exhibited the most compelling efficacy and selectivity with an EC50 of <3.54 μM and SI of >15.3. The results are valuable for the development of novel antiviral drug leads against emerging diseases. 相似文献
72.
Chi-Huang Chen Tsai-Chin Shih Yung-Liang Liu Yi-Jen Peng Ya-Li Huang Brian Shiian Chen How Tseng 《International journal of molecular sciences》2022,23(20)
Prepubertal boys with cancer may suffer from reduced fertility and maturity following gonadotoxic chemoradiotherapy. Thus, a viable method of immature testicular tissue (ITT) preservation is required in this cohort. In this study, we used poly-L-lactic acid electrospun scaffolds with two levels of fineness to support the development of ITT transplanted from transgenic donors to wild-type recipient mice. The purpose of this study was to evaluate the potential of ITT transplantation and spermatogenesis after using the two scaffolds, employing bioluminescence imaging for evaluation. The results suggest that ITT from 4-week-old mice possessed the most potential in spermatogenesis on the 70th day, together with the fine electrospun scaffolds. Moreover, bioluminescent imaging intensity was observed in recipient mice for up to 107 days, approximately six times more than the coarse electrospun scaffold and the control group. This occurs since the fine scaffold is more akin to the microenvironment of native testicular tissue as it reduces stiffness resulting from micronization and body fluid infiltration. The thermal analysis also exhibited recrystallization during the biodegradation process, which can lead to a more stable microenvironment. Overall, these findings present the prospect of fertility preservation in prepubertal males and could serve as a framework for future applications. 相似文献
73.
Wan-Xuan Ho Wen-Ting Chen Chih-Hsuan Lien Hsin-Yu Yang Kuan-Hung Chen Yu-Fan Wei Meng-Han Wang I-Ting Ko Fan-Gang Tseng Hsien-Sheng Yin 《International journal of molecular sciences》2022,23(17)
We previously developed chicken interleukin-1β (IL-1β) mutants as single-dose adjuvants that induce protective immunity when co-administered with an avian vaccine. However, livestock such as pigs may require a vaccine adjuvant delivery system that provides long-lasting protection to reduce the need for successive booster doses. Therefore, we developed chitosan-coated alginate microparticles as a carrier for bovine serum albumin (BSA) or porcine IL-1β (pIL-1β) and assessed their physical, chemical, and biological properties. Electrospraying of the BSA-loaded alginate microparticles (BSA/ALG MPs) resulted in an encapsulation efficiency of 50%, and those MPs were then coated with chitosan (BSA/ALG/CHI MPs). Optical and scanning electron microscopy, zeta potential analysis, and Fourier transform infrared spectroscopy were used to characterize these MPs. The BSA encapsulation parameters were applied to ALG/CHI MPs loaded with pIL-1β, which were not cytotoxic to porcine fibroblasts but had enhanced bio-activity over unencapsulated pIL-1β. The chitosan layer of the BSA/ALG/CHI MPs prevented burst release and facilitated sustained release of pIL-1β for at least 28 days. In conclusion, BSA/ALG/CHI MPs prepared as a carrier for pIL-1β may be used as an adjuvant for the formulation of pig vaccines. 相似文献
74.
IEEE 802.15.3, an emerging wireless technology, was designed to provide high-quality multimedia services at home. Dynamic bandwidth allocation for a multimedia connection should be considered in order to achieve higher channel utilization, less buffer and less delay, especially for variable bit rate (VBR) multimedia connections. For real-time VBR videos, the bandwidth requirement should be predicted adaptively for effective channel-time requests. Previously, the adaptive least-mean square (LMS) algorithm with fixed step size was applied to predict channel time requirements due to its simplicity and relatively good performance. However, the performance might degrade when scene changes occurred. In this paper, we modify the variable step-size LMS algorithm and apply it as our predictor (VSSNLMS) so that the prediction errors on scene changes can be effectively reduced. Using the prediction results of VSSNLMS, we propose a dynamic bandwidth-allocation scheme that is scene-change aware and can guarantee the delay bound of real-time VBR videos. Simulation results show that the VSSNLMS predictor is superior to previous LMS-type predictors in performance, and the proposed scheme has better performance in channel utilization, buffer usage, and packet loss 相似文献
75.
Effects of three‐dimensional virtual reality and traditional training methods on mental workload and training performance 下载免费PDF全文
Chin‐Jung Chao Sheng‐Yu Wu Yi‐Jan Yau Weng‐Yan Feng Feng‐Yi Tseng 《人机工程学与制造业中的人性因素》2017,27(4):187-196
Industries will implement effective training programs to improve training performance, and an ideal training performance occurs under proper mental workload (MWL). Virtual reality (VR) has recently been widely utilized in training; however, only a few studies have investigated its effects on MWL and training performance simultaneously. The purpose of this study is to investigate the effects of VR training and traditional training methods, such as technical manuals (TM) and multimedia films (MF), on training performance and MWL. The results of the performance measurement show that VR training is considered the best training method compared to TM and MF, particularly in the case of complex tasks. The results of physiological measurements (GSR [galvanic skin response], LF% [low frequency], and LF/HF [high frequency] ratio) show a significant difference between reading TM and using computer (MF and VR), wherein the latter has a lower MWL. However, no significant difference in subjective MWL assessment (NASA‐TLX [task load index]) and HF% measurement is found. 相似文献
76.
An improved approach to find membership functions and multiple minimum supports in fuzzy data mining
Chun-Hao Chen Tzung-Pei Hong Vincent S. Tseng 《Expert systems with applications》2009,36(6):10016-10024
Fuzzy mining approaches have recently been discussed for deriving fuzzy knowledge. Since items may have their own characteristics, different minimum supports and membership functions may be specified for different items. In the past, we proposed a genetic-fuzzy data-mining algorithm for extracting minimum supports and membership functions for items from quantitative transactions. In that paper, minimum supports and membership functions of all items are encoded in a chromosome such that it may be not easy to converge. In this paper, an enhanced approach is proposed, which processes the items in a divide-and-conquer strategy. The approach is called divide-and-conquer genetic-fuzzy mining algorithm for items with Multiple Minimum Supports (DGFMMS), and is designed for finding minimum supports, membership functions, and fuzzy association rules. Possible solutions are evaluated by their requirement satisfaction divided by their suitability of derived membership functions. The proposed GA framework maintains multiple populations, each for one item’s minimum support and membership functions. The final best minimum supports and membership functions in all the populations are then gathered together to be used for mining fuzzy association rules. Experimental results also show the effectiveness of the proposed approach. 相似文献
77.
78.
Design and implementation of a high‐efficiency LiFePO4 battery charger for electric vehicle applications 下载免费PDF全文
Huang‐Jen Chiu Yu‐Kang Lo Po‐Jung Tseng Yu‐Chen Liu Yu‐Chen Chang Ym‐Min Liao Kuo‐Kuang Jen Kuo‐Sheng Fu Chih‐Hsien Chung Kun‐Feng Chen 《International Journal of Circuit Theory and Applications》2014,42(7):759-768
This letter studies and implements a high‐efficiency LiFePO4 battery charger. The modular design can satisfy the requirements of series/parallel charging for electric vehicle applications. A CC‐CC‐CV charging scheme is also realized to meet the characteristics of LiFePO4 battery stacks. A 2 kW laboratory prototype is built and tested. The experimental results are shown to verify the feasibility of the proposed scheme. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
79.
80.
Searching on the Web has never been an easy task. Even if semantic information is successfully inferred from a user query, how can we benefit from it? The most popular remedy today is to categorize the Web in advance. By gathering similar Web resources into a group, the search performance should increase even though search engines still have little idea about the semantics part. To categorize a set of Web resources according to meta-information associated with them, at first, one has to analyze the relationships between meta-information and Web resources. However, the result will be severely affected by the ambiguous nature of the Web. As a result, the goal of this research is to propose a new labeling method to enhance both the efficiency and accuracy of Web resources categorization. 相似文献