首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   87422篇
  免费   10882篇
  国内免费   6486篇
电工技术   3061篇
技术理论   8篇
综合类   10516篇
化学工业   2156篇
金属工艺   1074篇
机械仪表   3916篇
建筑科学   32104篇
矿业工程   2340篇
能源动力   794篇
轻工业   1400篇
水利工程   4863篇
石油天然气   1215篇
武器工业   564篇
无线电   11109篇
一般工业技术   4276篇
冶金工业   1550篇
原子能技术   258篇
自动化技术   23586篇
  2024年   183篇
  2023年   974篇
  2022年   1932篇
  2021年   2424篇
  2020年   2312篇
  2019年   1642篇
  2018年   1584篇
  2017年   2053篇
  2016年   2560篇
  2015年   3186篇
  2014年   8884篇
  2013年   5367篇
  2012年   7472篇
  2011年   7711篇
  2010年   6967篇
  2009年   7115篇
  2008年   6789篇
  2007年   7360篇
  2006年   5651篇
  2005年   4512篇
  2004年   3835篇
  2003年   3239篇
  2002年   2519篇
  2001年   1882篇
  2000年   1478篇
  1999年   1024篇
  1998年   760篇
  1997年   674篇
  1996年   525篇
  1995年   431篇
  1994年   345篇
  1993年   266篇
  1992年   217篇
  1991年   138篇
  1990年   149篇
  1989年   117篇
  1988年   84篇
  1987年   55篇
  1986年   68篇
  1985年   66篇
  1984年   58篇
  1983年   52篇
  1982年   28篇
  1981年   17篇
  1980年   9篇
  1979年   6篇
  1965年   7篇
  1960年   7篇
  1959年   6篇
  1958年   5篇
排序方式: 共有10000条查询结果,搜索用时 250 毫秒
51.
Abstract

The study of order-of-addition (OofA) experiments is prevalent in many scientific and industrial areas. The statistical design of experiments (DOE) will considerably improve the efficiency of OofA experiments. Designing and modeling the OofA experiments have increasingly received a great deal of attention. In this article, we review the latest work on the design and model of OofA experiments, and introduce some new thoughts. We believe that this article will motivate fruitful applications in real OofA experiments as well as future developments in the methodology.  相似文献   
52.
53.
Objective and quantitative assessment of skin conditions is essential for cosmeceutical studies and research on skin aging and skin regeneration. Various handcraft-based image processing methods have been proposed to evaluate skin conditions objectively, but they have unavoidable disadvantages when used to analyze skin features accurately. This study proposes a hybrid segmentation scheme consisting of Deeplab v3+ with an Inception-ResNet-v2 backbone, LightGBM, and morphological processing (MP) to overcome the shortcomings of handcraft-based approaches. First, we apply Deeplab v3+ with an Inception-ResNet-v2 backbone for pixel segmentation of skin wrinkles and cells. Then, LightGBM and MP are used to enhance the pixel segmentation quality. Finally, we determine several skin features based on the results of wrinkle and cell segmentation. Our proposed segmentation scheme achieved a mean accuracy of 0.854, mean of intersection over union of 0.749, and mean boundary F1 score of 0.852, which achieved 1.1%, 6.7%, and 14.8% improvement over the panoptic-based semantic segmentation method, respectively.  相似文献   
54.
Structural bonding and bonded repairs of composite materials become more and more important. Understanding the strain within the bondline leads to suitable bonding design. For new design approaches the strain distribution within the bondline has to be analyzed. Thus, often finite element analysis (FE) are used. However, a huge challenge is the availability of reliable material properties for the adhesives and their validation. Previous work has shown that it is possible to measure the small displacements resulting within thin epoxy film adhesives using high resolution digital image correlation (DIC). In this work a 2D DIC setup with a high resolution consumer camera is used to visualize the strain distribution within the bondline over the length of the joint as well as over the adhesive thickness. Therefore, single lap joints with thick aluminum adherends according to ASTM D 5656 are manufactured and tested. Local 2D DIC strain measurements are performed and analyzed. Two different camera setups are used and compared. The evaluation provides reliable material data and enables a look insight the bondline. The results of the full field strain data measured with DIC are compared with numerical simulations. Thus, material models as well as chosen parameters for the adhesive are validated. Compared to extensometers, giving only point-wise information for fixed measuring points, the DIC allows a virtual point-wise inspection along the complete bondline. Furthermore, it allows measuring close to the bondline to reduce the influence of adherend deformation.  相似文献   
55.
为了更加有效地检索到符合用户复杂语义需求的图像,提出一种基于文本描述与语义相关性分析的图像检索算法。该方法将图像检索分为两步:基于文本语义相关性分析的图像检索和基于SIFT特征的相似图像扩展检索。根据自然语言处理技术分析得到用户文本需求中的关键词及其语义关联,在选定图像库中通过语义相关性分析得到“种子”图像;接下来在图像扩展检索中,采用基于SIFT特征的相似图像检索,利用之前得到的“种子”图像作为查询条件,在网络图像库中进行扩展检索,并在结果集上根据两次检索的图像相似度进行排序输出,最终得到更加丰富有效的图像检索结果。为了证明算法的有效性,在标准数据集Corel5K和网络数据集Deriantart8K上完成了多组实验,实验结果证明该方法能够得到较为精确地符合用户语义要求的图像检索结果,并且通过扩展算法可以得到更加丰富的检索结果。  相似文献   
56.
〖HTH〗通讯作者〖HTSS〗:[ZK(]金〓燕(1991-),女,山东济宁人,硕士研究生,主要从事图形图像处理,图像与视觉信息计算方面的研究。E\|mail:jyan0529@163.com。[ZK)] 〖ZW)〗〖HT〗 〖AM〗〖HT5SS〗〖MM(〗〖ZZ(S〗〖HT5”〗〖SX(B〗第34卷〓第3期〖〗2019年6月〖SX)〗[KG0.2mm]〖KG7*3〗〖HT〗〖SX(B〗遥〓感〓技〓术〓与〓应〓用〖〗〖WT5,6〗REMOTE SENSING TECHNOLOGY AND APPLICATION〖SX)〗〓〓〓〓〖KG6*2〗〖WT5”BX〗〖SX(B〗Vol.34〓No.3〖〗Jun.2019〖WT〗〖SX)〗〖ZZ)〗〖MM)〗〖HT〗 〖HT2H〗〖JZ(〗〖WTHZ〗〖STHZ〗 基于Marr小波改进的SIFT算法的遥感影像配准 〖STBZ〗〖WTBZ〗〖HT4K〗 张海涛,金〓燕,刘万军 〖HT5K〗 (辽宁工程技术大学 软件学院,辽宁 葫芦岛〓125105) 〖JZ)〗〖HT5H〗〖GK2!2〗摘要〖HTK〗: [KG(0.1mm]针对遥感图像配准方法中错误匹配点对过多、配准效率低和其他性能,提出了一种基于小波的遥感图像配准方法。首先,利用尺度空间理论下的Marr小波对参考图像和待配准图像进行特征提取,然后利用欧氏距离对参考图像和待配准图像的特征点进行初配准,再根据随机采样一致法,对初配准结果进行精配准。为了验证方法的有效性,选择无人机实时航拍图像、不同时相变化遥感图像以及遥感不同高度的遥感图像。实验结果表明:该方法与SIFT(Scale Invariant Feature Transform)算法以及其他改进SIFT算法相比可以有效剔除错误匹配点对,提高了配准精度,同时提高配准效率两倍以上。该方法可以应用于不同遥感数据源,能够有效地提高配准精度,降低配准时间。[KG)] 〖HTH〗关〓键〓词〖HT5K〗: 遥感图像配准;Marr小波;欧氏距离;随机采样一致法 〖HTH〗中图分类号〖HTSS〗:TP79〓〓〖HTH〗文献标志码〖HTSS〗:A〓〓〖HTH〗文章编号〖HTSS〗:1004 0323(2019)03 0622 08 〖HK〗〖HT5SS〗  相似文献   
57.
Low-light images enhancement is a challenging task because enhancing image brightness and reducing image degradation should be considered simultaneously. Although existing deep learning-based methods improve the visibility of low-light images, many of them tend to lose details or sacrifice naturalness. To address these issues, we present a multi-stage network for low-light image enhancement, which consists of three sub-networks. More specifically, inspired by the Retinex theory and the bilateral grid technique, we first design a reflectance and illumination decomposition network to decompose an image into reflectance and illumination maps efficiently. To increase the brightness while preserving edge information, we then devise an attention-guided illumination adjustment network. The reflectance and the adjusted illumination maps are fused and refined by adversarial learning to reduce image degradation and improve image naturalness. Experiments are conducted on our rebuilt SICE low-light image dataset, which consists of 1380 real paired images and a public dataset LOL, which has 500 real paired images and 1000 synthetic paired images. Experimental results show that the proposed method outperforms state-of-the-art methods quantitatively and qualitatively.  相似文献   
58.
59.
60.
Urdu is a widely spoken language in the Indian subcontinent with over 300 million speakers worldwide. However, linguistic advancements in Urdu are rare compared to those in other European and Asian languages. Therefore, by following Text Retrieval Conference standards, we attempted to construct an extensive text collection of 85 304 documents from diverse categories covering over 52 topics with relevance judgment sets at 100 pool depth. We also present several applications to demonstrate the effectiveness of our collection. Although this collection is primarily intended for text retrieval, it can also be used for named entity recognition, text summarization, and other linguistic applications with suitable modifications. Ours is the most extensive existing collection for the Urdu language, and it will be freely available for future research and academic education.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号