全文获取类型
收费全文 | 48558篇 |
免费 | 7392篇 |
国内免费 | 5382篇 |
专业分类
电工技术 | 5167篇 |
技术理论 | 1篇 |
综合类 | 6665篇 |
化学工业 | 3798篇 |
金属工艺 | 1972篇 |
机械仪表 | 4520篇 |
建筑科学 | 5504篇 |
矿业工程 | 1904篇 |
能源动力 | 1475篇 |
轻工业 | 1582篇 |
水利工程 | 1809篇 |
石油天然气 | 1646篇 |
武器工业 | 1058篇 |
无线电 | 4199篇 |
一般工业技术 | 5391篇 |
冶金工业 | 1290篇 |
原子能技术 | 293篇 |
自动化技术 | 13058篇 |
出版年
2024年 | 341篇 |
2023年 | 861篇 |
2022年 | 1551篇 |
2021年 | 1707篇 |
2020年 | 1868篇 |
2019年 | 1555篇 |
2018年 | 1560篇 |
2017年 | 1854篇 |
2016年 | 2195篇 |
2015年 | 2278篇 |
2014年 | 3146篇 |
2013年 | 3114篇 |
2012年 | 4043篇 |
2011年 | 3958篇 |
2010年 | 3142篇 |
2009年 | 3112篇 |
2008年 | 3101篇 |
2007年 | 3697篇 |
2006年 | 3137篇 |
2005年 | 2654篇 |
2004年 | 2080篇 |
2003年 | 1725篇 |
2002年 | 1411篇 |
2001年 | 1271篇 |
2000年 | 1121篇 |
1999年 | 879篇 |
1998年 | 709篇 |
1997年 | 626篇 |
1996年 | 513篇 |
1995年 | 424篇 |
1994年 | 367篇 |
1993年 | 270篇 |
1992年 | 217篇 |
1991年 | 181篇 |
1990年 | 152篇 |
1989年 | 146篇 |
1988年 | 93篇 |
1987年 | 49篇 |
1986年 | 27篇 |
1985年 | 28篇 |
1984年 | 35篇 |
1983年 | 26篇 |
1982年 | 23篇 |
1981年 | 10篇 |
1980年 | 21篇 |
1979年 | 19篇 |
1977年 | 4篇 |
1959年 | 5篇 |
1955年 | 5篇 |
1951年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
In this paper, the dynamic behaviors on the basis of simulation for high-purity heat integrated air separation column (HIASC) are studied. A nonlinear generic model control (GMC) scheme is proposed based on the nonlinear behavior analyses of a HIASC process, and an adaptive generic model control (AGMC) scheme is further presented to correct the model parameters online. Related internal model control (IMC) scheme and multi-loop PID (M-PID) scheme are also developed as the comparative base. The comparative researches are carried out among these linear and nonlinear control schemes in detail. The simulation research results show that the proposed AGMC schemes present advantages in both servo control and regulatory control for the high-purity HIASC. 相似文献
4.
Zhijiang Li Yingping Zheng Liqin Cao Lei Jiao Yanfei Zhong Caiyi Zhang 《Color research and application》2020,45(4):656-670
Image color clustering is a basic technique in image processing and computer vision, which is often applied in image segmentation, color transfer, contrast enhancement, object detection, skin color capture, and so forth. Various clustering algorithms have been employed for image color clustering in recent years. However, most of the algorithms require a large amount of memory or a predetermined number of clusters. In addition, some of the existing algorithms are sensitive to the parameter configurations. In order to tackle the above problems, we propose an image color clustering method named Student's t-based density peaks clustering with superpixel segmentation (tDPCSS), which can automatically obtain clustering results, without requiring a large amount of memory, and is not dependent on the parameters of the algorithm or the number of clusters. In tDPCSS, superpixels are obtained based on automatic and constrained simple non-iterative clustering, to automatically decrease the image data volume. A Student's t kernel function and a cluster center selection method are adopted to eliminate the dependence of the density peak clustering on parameters and the number of clusters, respectively. The experiments undertaken in this study confirmed that the proposed approach outperforms k-means, fuzzy c-means, mean-shift clustering, and density peak clustering with superpixel segmentation in the accuracy of the cluster centers and the validity of the clustering results. 相似文献
5.
6.
Journal of Computer Science and Technology - DOACROSS loops are significant parts in many important scientific and engineering applications, which are generally exploited pipeline/wave-front... 相似文献
7.
In this paper, we first re-examine the previous protocol of controlled quantum secure direct communication of Zhang et al.’s scheme, which was found insecure under two kinds of attacks, fake entangled particles attack and disentanglement attack. Then, by changing the party of the preparation of cluster states and using unitary operations, we present an improved protocol which can avoid these two kinds of attacks. Moreover, the protocol is proposed using the three-qubit partially entangled set of states. It is more efficient by only using three particles rather than four or even more to transmit one bit secret information. Given our using state is much easier to prepare for multiqubit states and our protocol needs less measurement resource, it makes this protocol more convenient from an applied point of view. 相似文献
8.
Mingchang Lin Yufei Zhang Guosong Chen Ming Jiang 《Small (Weinheim an der Bergstrasse, Germany)》2015,11(45):6065-6070
Glyco‐mimicking nanoparticles (glyco‐NPs) with Förster resonance energy transfer (FRET) donor and acceptor groups formed via dynamic covalent bond of benzoboroxole and sugar from two complementary polymers are prepared. The glyco‐NPs are proved to be quite stable under physiological conditions but sensitive to pH. So the glyco‐NPs can be internalized by dendritic cells with integrity and nontoxicity and then dissociate within the acidic organelles. This particle dissociation is directly observed and visualized in vitro, for the first time via the FRET measurements and fluorescent microscopy. This feature makes controlled release of drug or protein by glyco‐NPs possible, i.e., when model antigen Ovalbumin is loaded in the glyco‐NPs, the released Ovalbumin in dendritic cells stimulates T cells more efficiently than the free Ovalbumin itself as a result of the enhanced antigen processing and presentation. Thus, the results enlighten a bright future of the glyco‐NPs in immunotherapy. 相似文献
9.