全文获取类型
收费全文 | 98553篇 |
免费 | 12109篇 |
国内免费 | 7529篇 |
专业分类
电工技术 | 7962篇 |
技术理论 | 1篇 |
综合类 | 9001篇 |
化学工业 | 13802篇 |
金属工艺 | 6171篇 |
机械仪表 | 6626篇 |
建筑科学 | 7015篇 |
矿业工程 | 3180篇 |
能源动力 | 2341篇 |
轻工业 | 11307篇 |
水利工程 | 3027篇 |
石油天然气 | 4006篇 |
武器工业 | 1254篇 |
无线电 | 11223篇 |
一般工业技术 | 9638篇 |
冶金工业 | 3915篇 |
原子能技术 | 1815篇 |
自动化技术 | 15907篇 |
出版年
2024年 | 300篇 |
2023年 | 1612篇 |
2022年 | 3474篇 |
2021年 | 4551篇 |
2020年 | 3390篇 |
2019年 | 2609篇 |
2018年 | 2863篇 |
2017年 | 3033篇 |
2016年 | 2865篇 |
2015年 | 4342篇 |
2014年 | 5457篇 |
2013年 | 6553篇 |
2012年 | 7909篇 |
2011年 | 8624篇 |
2010年 | 8130篇 |
2009年 | 8034篇 |
2008年 | 7838篇 |
2007年 | 7563篇 |
2006年 | 6639篇 |
2005年 | 5496篇 |
2004年 | 3950篇 |
2003年 | 2766篇 |
2002年 | 2604篇 |
2001年 | 2401篇 |
2000年 | 1744篇 |
1999年 | 947篇 |
1998年 | 436篇 |
1997年 | 381篇 |
1996年 | 320篇 |
1995年 | 247篇 |
1994年 | 203篇 |
1993年 | 183篇 |
1992年 | 129篇 |
1991年 | 105篇 |
1990年 | 81篇 |
1989年 | 78篇 |
1988年 | 48篇 |
1987年 | 44篇 |
1986年 | 43篇 |
1985年 | 13篇 |
1984年 | 14篇 |
1983年 | 20篇 |
1982年 | 18篇 |
1981年 | 14篇 |
1980年 | 17篇 |
1979年 | 19篇 |
1977年 | 10篇 |
1976年 | 13篇 |
1975年 | 9篇 |
1951年 | 20篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
Tumor cell aggregation is critical for cell survival following the loss of extracellular matrix attachment and dissemination. However, the underlying mechanotransduction of clustering solitary tumor cells is poorly understood, especially in non-small cell lung cancers (NSCLC). Here, we examined whether cell surface protrusions played an important role in facilitating the physical contact between floating cells detached from a substrate. We employed poly-2-hydroxyethyl methacrylate-based 3D culture methods to mimic in vivo tumor cell cluster formation. The suprastructural analysis of human NSCLC A549 cell spheroids showed that finger-like protrusions clung together via the actin cytoskeleton. Time-lapse holotomography demonstrated that the finger-like protrusions of free-floating cells in 3D culture displayed exploratory coalescence. Global gene expression analysis demonstrated that the genes in the organic hydroxyl transport were particularly enriched in the A549 cell spheroids. Particularly, the knockdown of the water channel aquaporin 3 gene (AQP3) impaired multicellular aggregate formation in 3D culture through the rearrangement of the actomyosin cytoskeleton. Moreover, the cells with reduced levels of AQP3 decreased their transmigration. Overall, these data indicate that cell detachment-upregulated AQP3 contributes to cell surface protrusions through actomyosin cytoskeleton remodeling, causing the aggressive aggregation of free-floating cells dependent on the property of the substratum and collective metastasis. 相似文献
4.
5.
Min Ma Wan-Chang Sun Ya-Ru Dong Ya-Gang Zhang Yu-Wan Liu Sha-Sha Tian Yan Xiao 《工业材料与腐蚀》2021,72(5):912-924
Diamond-like carbon (DLC) possesses brilliant and excellent properties, including excellent corrosion resistance as well as outstanding wear resistance. Ni and B co-doped DLC films were deposited on AZ91D magnesium alloy by electrodeposition under mild conditions (300 V and 25°C). Uniform and dense morphology of co-doped DLC films were observed, and Ni and B were uniformly incorporated into the carbon-based films. Among all the electrodeposits, the appearance of D and G peaks near 1330 and 1570 cm−1 revealed that the as-deposited films were typical DLC films. As the addition of Ni was increased to 0.05 g, the highest microindentation hardness, the lowest friction coefficient, and wear loss were achieved to be 164.5 HV, 0.3, and 0.6 × 10−5 kg/m, respectively. The amorphous carbon films fabricated at 0.05 g Ni had the lowest corrosion current density and the most positive corrosion potential, which was mainly due to the small and dense granular structure effectively hindering the penetration of corrosion media. 相似文献
6.
7.
图像中的天空区域对于基于视觉的地面机器人导航具有重要意义,为了识别图像中的天空部分,本文提出了一种基于像素偏转模型的BP神经网络天空识别方法.首先,制作天空图像集和非天空图像集,天空图像集由各种天气情况下的天空提取而成,非天空图像集由非天空的景物构成,主要包括建筑、汽车、树木、植物等;其次,使用提出的像素偏转模型提取天空图像集和非天空图像集的像素特征并进行处理,对天空像素点和非天空像素点进行标注,利用BP神经网络对像素特征进行训练,得到权重文件;最后,使用得到的权重文件进行天空的识别.为了更好的说明本文算法和模型的优越性,使用本文算法与Otsu算法、YeHu算法、Graph-cut算法和Mask-Rcnn算法模型进行了比较,并设计了两组组对比实验,第一组实验进行识别效果的主观评价,第二组实验利用CamVid数据集的天空类进行算法精度的定量分析. 相似文献
8.
现代学徒制是一项深化产教融合、校企合作的育人机制,是创新技术技能人才的现代培养模式.山西铁道职业技术学院与山西安泰控股集团有限公司深度合作开展山西省现代学徒制试点项目,合作目的之一是培养企业煤化工专业人才.学校教师结合学生(员工)在企业车间岗位上的技能知识,系统地讲授煤化工专业课程"煤质分析及煤化工产品检验"理论知识,同时针对企业员工日常学习思想政治知识较少的实际,润物细无声地加入思政元素,实现专业知识与实践技能相结合,技能知识与思政教育相融合,真正培养知识型、技能型、创新型高素质技能人才,努力构建职业教育产业发展命运共同体. 相似文献
9.
10.
Fanbo Meng Mingchang Zhang Jin Huang Wen Feng Lu Jun Min Xue Hao Wang 《Advanced functional materials》2021,31(9):2008280
The development of the Internet of things has prompted an exponential increase in the demand for flexible, wearable devices, thereby posing new challenges to their integration and conformalization. Additive manufacturing facilitates the fabrication of complex parts via a single integrated process. Herein, the development of a multinozzle, multimaterial printing device is reported. This device accommodates the various characteristics of printing materials, ensures high-capacity printing, and can accommodate a wide range of material viscosities from 0 to 1000 Cp. Complete capacitors, inclusive of the current collector, electrode, and electrolyte, can be printed without repeated clamping to complete the preheating, printing, and sintering processes. This method addresses the poor stability issue associated with printed electrode materials. Furthermore, after the intercalation of LiFePO4 with Na ions, X-ray photoelectron spectroscopy and X-ray diffraction results reveal that the Na ions permeate the interlayer structure of LiFePO4, enhancing the ion migration channels by increasing the ion transmission rate. A current rate of 2.5 mAh ensures >2000 charge/discharge cycles, while retaining a charge/discharge efficiency of 96% and a discharge capacity of 91.3 mAh g−1. This manufacturing process can provide conformal power modules for a diverse range of portable devices with various shapes, improving space utilization. 相似文献