全文获取类型
收费全文 | 7202篇 |
免费 | 230篇 |
国内免费 | 45篇 |
专业分类
电工技术 | 133篇 |
综合类 | 24篇 |
化学工业 | 838篇 |
金属工艺 | 110篇 |
机械仪表 | 198篇 |
建筑科学 | 347篇 |
矿业工程 | 4篇 |
能源动力 | 148篇 |
轻工业 | 302篇 |
水利工程 | 23篇 |
石油天然气 | 27篇 |
武器工业 | 3篇 |
无线电 | 1473篇 |
一般工业技术 | 1027篇 |
冶金工业 | 1756篇 |
原子能技术 | 33篇 |
自动化技术 | 1031篇 |
出版年
2023年 | 40篇 |
2022年 | 76篇 |
2021年 | 93篇 |
2020年 | 59篇 |
2019年 | 70篇 |
2018年 | 106篇 |
2017年 | 82篇 |
2016年 | 135篇 |
2015年 | 112篇 |
2014年 | 134篇 |
2013年 | 320篇 |
2012年 | 305篇 |
2011年 | 324篇 |
2010年 | 238篇 |
2009年 | 297篇 |
2008年 | 328篇 |
2007年 | 317篇 |
2006年 | 306篇 |
2005年 | 255篇 |
2004年 | 206篇 |
2003年 | 215篇 |
2002年 | 158篇 |
2001年 | 171篇 |
2000年 | 167篇 |
1999年 | 209篇 |
1998年 | 681篇 |
1997年 | 378篇 |
1996年 | 293篇 |
1995年 | 215篇 |
1994年 | 142篇 |
1993年 | 173篇 |
1992年 | 84篇 |
1991年 | 76篇 |
1990年 | 59篇 |
1989年 | 59篇 |
1988年 | 57篇 |
1987年 | 54篇 |
1986年 | 47篇 |
1985年 | 67篇 |
1984年 | 27篇 |
1983年 | 24篇 |
1982年 | 40篇 |
1981年 | 37篇 |
1980年 | 32篇 |
1979年 | 24篇 |
1978年 | 17篇 |
1977年 | 32篇 |
1976年 | 57篇 |
1975年 | 17篇 |
1973年 | 19篇 |
排序方式: 共有7477条查询结果,搜索用时 15 毫秒
91.
运用光刻胶为注模的多次互不干扰金属电镀技术实现了惯性微型电学开关的低温制造与封装.电镀技术的低温过程可使微型开关直接成形于预先制作好的含有电子信号处理电路的基底上,加上同样借助于低温金属电镀技术的基于整个硅晶片的倒装封装,直接形成环绕各个器件的密封腔体.这一技术最终将使得模块化生产成为现实.微型开关的高度和它的密封腔的高度可以分别控制.电子信号可以通过金属互连线进入密封腔体.为了便于设计,建立了一个既简单又相对准确的"弹簧-质量块"模型.以此设计的惯性开关,即使在未封装的常温、常压条件下,均可工作109次以上.本文对密封腔体的强度和密封性,以及金属互连线的可靠性,都作了详细的检测,各项指标均达到其各自的标准. 相似文献
92.
P.K.J. Wong T.L.A. Tran P. Brinks W.G. van der Wiel M. Huijben M.P. de Jong 《Organic Electronics》2013,14(2):451-456
Hybrid interfaces between ferromagnetic surfaces and carbon-based molecules play an important role in organic spintronics. The fabrication of devices with well defined interfaces remains challenging, however, hampering microscopic understanding of their operation mechanisms. We have studied the crystallinity and molecular ordering of C60 films on epitaxial Fe/MgO(0 0 1) surfaces, using X-ray diffraction and scanning tunneling microscopy (STM). Both techniques confirm that fcc molecular C60 films with a (1 1 1)-texture can be fabricated on epitaxial bcc-Fe(0 0 1) surfaces at elevated growth temperatures (100–130 °C). STM measurements show that C60 monolayers deposited at 130 °C are highly ordered, exhibiting quasi-hexagonal arrangements on the Fe(0 0 1) surface oriented along the [1 0 0] and [0 1 0] directions. The mismatch between the surface lattice of the monolayer and the bulk fcc C60 lattice prevents epitaxial overgrowth of multilayers. 相似文献
93.
Statistical studies on the reflection coefficient of concrete–glass building facades are conducted using a fast and an accurate method based on the Green’s functions. The variation of different architectural parameters, such as concrete permitting and distribution, size and type of windows, are studied. The influence of selected parameters on the total reflection coefficient of the building is quantified for different incidence and observation angles as well as in different diffraction zones. 相似文献
94.
Broccoli, carrots, and green beans (grown in 2 consecutive years) were randomly divided into 3 treatments: fresh-refrigerated (F-R), frozen (FZ) or canned (C) (carrots only). FZ or C vegetables were processed within 24 h and stored for up to 1 yr. F-R vegetables were held at 4 °C for 3 wk (broccoli and green beans) or 6 mo (carrots). Trans b-carotene (Tb-C) and total ascorbic acid (AA) were determined at specified times, before and after microwave cooking. Vitamin content differed between years due to environmental conditions. Blanching resulted in AA loss, but retention remained stable after freezing broccoli and green beans. F-R green beans lost >90% AA after 16 d storage. Linear decreases in AAwere found in most F-R or FZ vegetables. Tb-C decreased slightly during freezer storage. Reductions in Tb-C occurred in canned carrots. Microwave cooking had minimal effects on AA or Tb-C. 相似文献
95.
Sugam Sharma Ritu Shandilya U. Sunday Tim Johnny Wong 《Telematics and Informatics》2018,35(2):446-456
Hunger is a global crisis and impacting the world for a very long time. Significant efforts have been made in the past by various organizations employing various means to address this persisting problem. Despite this, it still remains far from being resolved. Recently, the United Nations has published a report on global hunger, which claims that the global food production is fairly enough to feed the entire world with a population of about 7.3 billion. However, a major quantity of the food grown is not channeled appropriately and effectively to reach the needy and thus gets wasted unfortunately. Using the advanced computer technologies, we devise and develop a web-based computational framework (eFeed-Hungers.com) that serves as a bridge between the food waste and the hunger to mitigate the hunger issue; the food waste is the excess, unused, edible food, which otherwise is destined to the dumpster unfortunately. The eFeed-Hungers.com encourages and assists the food waste donation announcements with the least minimal efforts with the best possible outreach. Through the eFeed-Hungers.com, the food donations are globally searchable by the needy, with enough additional information imparted for quick decisions making to fetch the appropriate donated food. The eFeed-Hungers.com is envisioned to be a fully functional organization eventually with global outreach. 相似文献
96.
97.
Weiru Wang Chi-Man Vong Yilong Yang Pak-Kin Wong 《Multidimensional Systems and Signal Processing》2017,28(3):851-865
Nowadays, numerous corporations (such as Google, Baidu, etc.) require an efficient and effective search algorithm to crawl out the images with queried objects from databases. Moreover, privacy protection is a significant issue such that confidential images must be encrypted in corporations. Nevertheless, decrypting and then classifying millions of encrypted images becomes a heavy burden to computation. In this paper, we proposed an encrypted image classification framework based on multi-layer extreme learning machine that is able to directly classify encrypted images without decryption. Experiments were conducted on popular handwritten digits and letters databases. Results demonstrate that the proposed framework is secure, efficient and accurate for classifying encrypted images. 相似文献
98.
Alexander Wong Xiao Yu Wang 《Journal of Visual Communication and Image Representation》2012,23(7):984-994
This paper explores a stochastic approach to refining clustering results for data with spatial-feature context such as images under the presence of noise. We formulate the clustering problem as a maximum a posteriori (MAP) problem, and refine clustering results using importance-weighted Monte Carlo posterior estimates based on between-neighborhood error statistics to account for local spatial-feature context within a global framework. This cluster refinement approach is non-iterative and can be integrated with existing clustering methods to achieve improved clustering performance for image segmentation under high noise scenarios. Experiments on synthetic gray-level images, real-world natural images, and real-world satellite synthetic aperture radar imagery illustrate the proposed method’s potential for improving clustering performance of existing clustering algorithms for image segmentation under high noise situations. 相似文献
99.
Hao-Wu Lin Hao-Wei Kang Zheng-Yu Huang Chang-Wen Chen Yi-Hong Chen Li-Yen Lin Francis Lin Ken-Tsung Wong 《Organic Electronics》2012,13(10):1925-1929
Novel organic/ultrathin low work function metal bilayer cathode buffers for small molecule organic solar cells are proposed. Ultrathin low work function metal layers possess a high built-in electric field for effective carrier extraction and a high cathode reflectivity for maximum absorption in the photoactive layers. This leads to a significant increase of short circuit current density and fill factor of cells. By integrating this bilayer cathode buffer with DTDCTB:C60 small molecular heterojunction, the device exhibits a high power conversion efficiency of up to 5.28%, which is an improvement of 22% compared to a device with a traditional single organic layer buffer. 相似文献
100.
Quantitative measurement of cell cycle progression in individual cells over time is important in understanding drug treatment effects on cancer cells. Recent advances in time-lapse fluorescence microscopy imaging have provided an important tool to study the cell cycle process under different conditions of perturbation. However, existing computational imaging methods are rather limited in analyzing and tracking such time-lapse datasets, and manual analysis is unreasonably time-consuming and subject to observer variances. This paper presents an automated system that integrates a series of advanced analysis methods to fill this gap. The cellular image analysis methods can be used to segment, classify, and track individual cells in a living cell population over a few days. Experimental results show that the proposed method is efficient and effective in cell tracking and phase identification. 相似文献