全文获取类型
收费全文 | 324309篇 |
免费 | 28807篇 |
国内免费 | 19393篇 |
专业分类
电工技术 | 43820篇 |
技术理论 | 22篇 |
综合类 | 33210篇 |
化学工业 | 24096篇 |
金属工艺 | 15807篇 |
机械仪表 | 26114篇 |
建筑科学 | 24829篇 |
矿业工程 | 11227篇 |
能源动力 | 13017篇 |
轻工业 | 9914篇 |
水利工程 | 8429篇 |
石油天然气 | 10294篇 |
武器工业 | 4806篇 |
无线电 | 35975篇 |
一般工业技术 | 22500篇 |
冶金工业 | 11435篇 |
原子能技术 | 3668篇 |
自动化技术 | 73346篇 |
出版年
2024年 | 642篇 |
2023年 | 3476篇 |
2022年 | 6310篇 |
2021年 | 8207篇 |
2020年 | 8680篇 |
2019年 | 6742篇 |
2018年 | 6240篇 |
2017年 | 9000篇 |
2016年 | 10297篇 |
2015年 | 11836篇 |
2014年 | 20596篇 |
2013年 | 18468篇 |
2012年 | 24469篇 |
2011年 | 26169篇 |
2010年 | 19251篇 |
2009年 | 19722篇 |
2008年 | 19504篇 |
2007年 | 24345篇 |
2006年 | 21751篇 |
2005年 | 18802篇 |
2004年 | 15663篇 |
2003年 | 13939篇 |
2002年 | 10820篇 |
2001年 | 9171篇 |
2000年 | 7521篇 |
1999年 | 6045篇 |
1998年 | 4645篇 |
1997年 | 3987篇 |
1996年 | 3344篇 |
1995年 | 2851篇 |
1994年 | 2367篇 |
1993年 | 1622篇 |
1992年 | 1408篇 |
1991年 | 1067篇 |
1990年 | 842篇 |
1989年 | 649篇 |
1988年 | 476篇 |
1987年 | 265篇 |
1986年 | 202篇 |
1985年 | 193篇 |
1984年 | 173篇 |
1983年 | 143篇 |
1982年 | 109篇 |
1981年 | 87篇 |
1980年 | 86篇 |
1979年 | 68篇 |
1978年 | 41篇 |
1977年 | 37篇 |
1976年 | 26篇 |
1959年 | 32篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
71.
大型综合室内亲子乐园属于高大空间,设有游乐设施和游戏的特殊性使得对空间的舒适性要求一致,但是送风气流遇阻严重,室内存在较多气流死角,影响室内空气质量和儿童健康。因此其空调设计不仅需要考虑温度、风速的空间均匀度,还要考虑各点的空气龄和PMV-PPD指标。以天津某亲子乐园为研究对象,利用scSTREAM软件对适用于该房间的辐射供冷加新风、置换通风、混合通风三种空调方式的送风效果进行数值模拟分析,从流场的均匀性、人员的热舒适性等方面对模拟结果进行探讨,研究结果表明辐射供冷加新风方式的空间均匀性和PMV指标最佳,混合通风方式的空气龄最小。 相似文献
72.
Aishwarya
Srivastava Siddhant Aggarwal Amy Apon Edward Duffy Ken Kennedy Andre Luckow Brandon Posey Marcin Ziolkowski 《Software》2020,50(6):868-898
We investigate the challenges of building an end-to-end cloud pipeline for real-time intelligent visual inspection system for use in automotive manufacturing. Current methods of visual detection in automotive assembly are highly labor intensive, and thus prone to errors. An automated process is sought that can operate within the real-time constraints of the assembly line and can reduce errors. Components of the cloud pipeline include capture of a large set of high-definition images from a camera setup at the assembly location, transfer and storage of the images as needed, execution of object detection, and notification to a human operator when a fault is detected. The end-to-end execution must complete within a fixed time frame before the next car arrives in the assembly line. In this article, we report the design, development, and experimental evaluation of the tradeoffs of performance, accuracy, and scalability for a cloud system. 相似文献
73.
Aditi Chatterjee Jayabrata Biswas Kiranmoy Das 《International Journal of Communication Systems》2020,33(9)
In recent years, Internet of Things (IoT) devices are used for remote health monitoring. For remotely monitoring a patient, only the health information at different time points are not sufficient; predicted values of biomarkers (for some future time points) are also important. In this article, we propose a powerful statistical model for an efficient dynamic patient monitoring using wireless sensor nodes through Bayesian Learning (BL). We consider the setting where a set of correlated biomarkers are measured from a patient through wireless sensors, but the sensors only report the ordinal outcomes (say, good, fair, high, or very high) to the sink based on some prefixed thresholds. The challenge is to use the ordinal outcomes for monitoring and predicting the health status of the patient under consideration. We propose a linear mixed model where interbiomarker correlations and intrabiomarker dependence are modeled simultaneously. The estimated and the predicted values of the biomarkers are transferred over the internet so that health care providers and the family members of the patient can remotely monitor the patient. Extensive simulation studies are performed to assess practical usefulness of our proposed joint model, and the performance of the proposed joint model is compared to that of some other traditional models used in the literature. 相似文献
74.
Quadrature spatial modulation (QSM) utilizes the in‐phase and quadrature spatial dimensions to transmit the real and imaginary parts of a single signal symbol, respectively. The improved QSM (IQSM) transmits two signal symbols per channel use through a combination of two antennas for each of the real and imaginary parts. The main contributions of this study can be summarized as follows. First, we derive an upper bound for the error performance of the IQSM. We then design constellation sets that minimize the error performance of the IQSM for several system configurations. Second, we propose a double QSM (DQSM) that transmits the real and imaginary parts of two signal symbols through any available transmit antennas. Finally, we propose a parallel IQSM (PIQSM) that splits the antenna set into equal subsets and performs IQSM within each subset using the same two signal symbols. Simulation results demonstrate that the proposed constellations significantly outperform conventional constellations. Additionally, DQSM and PIQSM provide a performance similar to that of IQSM while requiring a smaller number of transmit antennas and outperform IQSM with the same number of transmit antennas. 相似文献
75.
76.
77.
This study proposes that a novel integrated circuit (IC) and system design for renewable energy inverters can harvest renewable energy to power direct current (DC) and alternating current (AC) loads. In addition, an intelligent synthesis and management tool is developed to design the proposed system and to judge the system’s operational maintenance decisions. Finally, a renewable energy inverter’s information is posted to an online system. Users can obtain the proposed system’s information at any time and place. The accurate and superior performance of the proposed IC and system is confirmed by computer simulations and experimental results. 相似文献
78.
Roberto Zefferino Claudia Piccoli Sante Di Gioia Nazzareno Capitanio Massimo Conese 《International journal of molecular sciences》2021,22(5)
Connexin- and pannexin (Panx)-formed hemichannels (HCs) and gap junctions (GJs) operate an interaction with the extracellular matrix and GJ intercellular communication (GJIC), and on account of this they are involved in cancer onset and progression towards invasiveness and metastatization. When we deal with cancer, it is not correct to omit the immune system, as well as neglecting its role in resisting or succumbing to formation and progression of incipient neoplasia until the formation of micrometastasis, nevertheless what really occurs in the tumor microenvironment (TME), which are the main players and which are the tumor or body allies, is still unclear. The goal of this article is to discuss how the pivotal players act, which can enhance or contrast cancer progression during two important process: “Activating Invasion and Metastasis” and the “Avoiding Immune Destruction”, with a particular emphasis on the interplay among GJIC, Panx-HCs, and the purinergic system in the TME without disregarding the inflammasome and cytokines thereof derived. In particular, the complex and contrasting roles of Panx1/P2X7R signalosome in tumor facilitation and/or inhibition is discussed in regard to the early/late phases of the carcinogenesis. Finally, considering this complex interplay in the TME between cancer cells, stromal cells, immune cells, and focusing on their means of communication, we should be capable of revealing harmful messages that help the cancer growth and transform them in body allies, thus designing novel therapeutic strategies to fight cancer in a personalized manner. 相似文献
79.
利用模糊控制和比例积分微分(PID)控制相结合的手段对注塑机料筒温度进行了控制,同时以Matlab 6.0软件为仿真平台,对料筒温度控制进行了模拟仿真研究。实验发现,在注塑机料筒升温过程中利用CHR整定的PID控制手段和模糊控制手段,恒温过程中利用人工整定的PID控制手段,可保证快速的料筒升温响应速率和稳定的保温过程。通过实际注塑实验对该仿真结果进行了验证,在十组实验中,料筒温度误差不超过2%,产品翘曲变形量不超过0.059 mm。 相似文献
80.
《Journal of the European Ceramic Society》2020,40(13):4676-4683
The Yaozhou kiln complex is a representative production center of ancient northern China, famous for the celadon production. In this work, bubbles, glassy matrix and residual crystals of celadon glazes produced from the Tang to Yuan Dynasty were analyzed by using optical microscopy, Raman spectroscopy and scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS). The results revealed that the Song, Jin and Yuan productions present bigger bubble and higher area ratios of the Si-O bending over stretching modes than the Tang and Wudai productions. This is consistent with firings at higher temperatures during Song, Jin and Yuan Dynasties. It is also in agreement with the historical studies, which revealed the change from wood-firing to coal-firing during Song Dynasty. The observation of calcium phosphate in Yaozhou productions indicated that the glaze ash had been used. No iron-based particle was identified by Raman spectroscopy in the glazes of all periods. The green color is certainly due to iron ion dispersed in the glassy matrix. Our study also confirmed no significant change in glaze raw materials used for Yaozhou productions from Tang to Yuan Dynasty. 相似文献