全文获取类型
收费全文 | 124538篇 |
免费 | 4587篇 |
国内免费 | 2385篇 |
专业分类
电工技术 | 2982篇 |
技术理论 | 7篇 |
综合类 | 5296篇 |
化学工业 | 18538篇 |
金属工艺 | 7188篇 |
机械仪表 | 5589篇 |
建筑科学 | 5409篇 |
矿业工程 | 1610篇 |
能源动力 | 2200篇 |
轻工业 | 6570篇 |
水利工程 | 2026篇 |
石油天然气 | 3026篇 |
武器工业 | 268篇 |
无线电 | 13591篇 |
一般工业技术 | 21124篇 |
冶金工业 | 4642篇 |
原子能技术 | 847篇 |
自动化技术 | 30597篇 |
出版年
2024年 | 144篇 |
2023年 | 682篇 |
2022年 | 1159篇 |
2021年 | 1712篇 |
2020年 | 1274篇 |
2019年 | 1022篇 |
2018年 | 15436篇 |
2017年 | 14540篇 |
2016年 | 11096篇 |
2015年 | 2196篇 |
2014年 | 2271篇 |
2013年 | 2705篇 |
2012年 | 5740篇 |
2011年 | 12187篇 |
2010年 | 10763篇 |
2009年 | 7961篇 |
2008年 | 9077篇 |
2007年 | 9830篇 |
2006年 | 2206篇 |
2005年 | 3086篇 |
2004年 | 2479篇 |
2003年 | 2534篇 |
2002年 | 1990篇 |
2001年 | 1474篇 |
2000年 | 1259篇 |
1999年 | 1182篇 |
1998年 | 950篇 |
1997年 | 768篇 |
1996年 | 705篇 |
1995年 | 527篇 |
1994年 | 460篇 |
1993年 | 319篇 |
1992年 | 259篇 |
1991年 | 200篇 |
1990年 | 147篇 |
1989年 | 128篇 |
1988年 | 102篇 |
1987年 | 62篇 |
1986年 | 62篇 |
1984年 | 32篇 |
1968年 | 44篇 |
1967年 | 34篇 |
1966年 | 46篇 |
1965年 | 46篇 |
1959年 | 36篇 |
1958年 | 37篇 |
1957年 | 36篇 |
1956年 | 34篇 |
1955年 | 63篇 |
1954年 | 68篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
11.
为了有效预测输电网系统在强风作用下的响应,并开展高效精准的性能评估,文章提出了基于深度学习模型的风致易损性评估框架。以某具备健康监测系统的输电塔结构为例,首先对监测数据进行清洗和重构,通过大数据深度学习建立荷载输入和响应输出的等效映射模型,然后通过数值模拟生成灾害强度均匀的风场数据并由深度学习模型预测输电塔关键杆件响应,计算不同性能水准的易损性曲线。研究结果表明,经训练的深度学习模型可以涵盖实际工程中存在的各类不确定性因素,有效映射复杂风环境下输电塔结构的动力响应。提出的框架方法可以避免单纯通过数值模型制备大量动态响应数据,更高效地进行输电网系统风致易损性评估。 相似文献
12.
Nengbing Long Yanqing Fu Tianxiang Xu Dashuang Ding Shaoqian Zhang Shengzhi Sun Shiliang Kang Tiefeng Xu Shixun Dai Qiuhua Nie Changgui Lin 《Journal of the European Ceramic Society》2021,41(8):4584-4589
The confinement of CsPbX3 (X = Cl, Br, and I) perovskite nanocrystals (NCs) in a stabilized inorganic glass matrix is a new strategy for improving their long-term stability and promoting their applications in the optoelectronic field. Here, in situ nanocrystallization strategy is developed to precipitate CsPbBr3?xIx NCs with arbitrary I/Br ratio among an elaborately designed GeS2–Sb2S3-based chalcogenide glass matrix. Spherical CsPbBr3?xIx NCs are homogeneously distributed in the glass matrix after thermal treatment. The photoluminescence (PL) spectra show that the emission peaks of CsPbBr3?xIx NCs can be tuned from 570 nm to 722 nm with the replacement of Br by I. The fs transient absorption (TA) spectra reveal that there exists some structural defects in the NCs, leading to short PL decay life. This work would shed light on confining CsPbX3 NCs into glassy matrices, facilitating their future applications in photoelectronic fields. 相似文献
13.
14.
Juan Ding Yong He Shenhe Fu Xiangsheng Xie Haowen Liang Jianying Zhou 《Journal of the Society for Information Display》2022,30(2):159-167
Illumination is essential for modern life as colorful world is perceived by human visionary system. Display technology has been developing rapidly in recent decades, and the basic principle is related to the way that the image is illuminated and light is emanated. Traditional illumination is provided by different types of light sources, and the display image is visible in large viewing space until the emanating light decays to zero. This work proposes and demonstrates a novel illumination scheme for a display in which the displaying images are visible only in specific spatial regions. The directional backlight ensures the image propagating to specific direction while imaging visibility can be controlled to terminate abruptly at certain distance from the display screen while exerting no influence to nearby regions. The working principle for such an illumination scheme is the use of the modulated coherent directional backlight through an axicon lens. It is shown that the illumination scheme can robustly deliver carried image information to the designated viewing region. This new illumination scheme has many advantages over conventional illumination, including its usage for personal display, very lower energy consumption, as well as minimizing light hazard pollution. 相似文献
15.
Magnetic Resonance Materials in Physics, Biology and Medicine - To investigate the value of using diffusion-weighted imaging (DWI) and intravoxel incoherent motion DWI (IVIM-DWI) to assess the... 相似文献
16.
伏彩萍 《有色金属(冶炼部分)》2020,(6):66-69
针对现有柠檬酸铋制备工艺合成时间长、能耗高、产品纯度不高等不足,介绍了一种常温下制备柠檬酸铋的新工艺。新工艺制备时间短,制备的柠檬酸铋产品质量好,合成过程产生的废水可循环利用,废气经碱液循环吸收可生产硝酸钠副产品。 相似文献
17.
18.
Qiaozhi Zhang Yanbo Wang Linglin Fu 《Comprehensive Reviews in Food Science and Food Safety》2020,19(5):2559-2587
Dietary advanced glycation end products (dAGEs) are complex and heterogeneous compounds derived from nonenzymatic glycation reactions during industrial processing and home cooking. There is mounting evidence showing that dAGEs are closely associated with various chronic diseases, where the absorbed dAGEs fuel the biological AGEs pool to exhibit noxious effects on human health. Currently, due to the uncertain bioavailability and rapid renal clearance of dAGEs, the relationship between dAGEs and biological AGEs remains debatable. In this review, we provide the most updated information on dAGEs including their generation in processed foods, analytical and characterization techniques, metabolic fates, interaction with AGE receptors, implications on human health and reducing strategies. Available evidence demonstrating a relevance between dAGEs and food allergy is also included. AGEs are ubiquitous in foods and their contents largely depend on the reactivity of carbonyl and amino groups, along with surrounding condition mainly pH and heating procedures. Once being digested and absorbed into the circulation, two separate pathways can be involved in the deleterious effects of dAGEs: an AGE receptor‐dependent way to stimulate cell signals, and an AGE receptor‐independent way to dysregulate proteins via forming complexes. Inhibition of AGEs formation during food processing and reduction in the diet are two potent approaches to restrict health‐hazardous dAGEs. To elucidate the biological role of dAGEs toward human health, the following significant perspectives are raised: molecular size and complexity of dAGEs; interactions between unabsorbed dAGEs and gut microbiota; and roles played by concomitant compounds in the heat‐processed foods. 相似文献
19.
Yong Xu Yun Li Songlin Li Francis Balestra Gerard Ghibaudo Wenwu Li Yen‐Fu Lin Huabin Sun Jing Wan Xinran Wang Yufeng Guo Yi Shi Yong‐Young Noh 《Advanced functional materials》2020,30(20)
Unreliable mobility values, and particularly greatly overestimated values and severely distorted temperature dependences, have recently hampered the development of the organic transistor field. Given that organic field‐effect transistors (OFETs) have been routinely used to evaluate mobility, precise parameter extraction using the electrical properties of OFETs is thus of primary importance. This review examines the origins of the various mobilities that must be determined for OFET applications, the relevant extraction methods, and the data selection limitations, which help in avoiding conceptual errors during mobility extraction. For increased precision, the review also discusses device fabrication considerations, calibration of both the specific gate‐dielectric capacitance and the threshold voltage, the contact effects, and the bias and temperature dependences, which must actually be handled with great care but have mostly been overlooked to date. This review serves as a systematic overview of the OFET mobility extraction process to ensure high precision and will also aid in improving future research. 相似文献
20.