全文获取类型
收费全文 | 31986篇 |
免费 | 2702篇 |
国内免费 | 1217篇 |
专业分类
电工技术 | 1705篇 |
综合类 | 910篇 |
化学工业 | 8022篇 |
金属工艺 | 739篇 |
机械仪表 | 1025篇 |
建筑科学 | 416篇 |
矿业工程 | 151篇 |
能源动力 | 10288篇 |
轻工业 | 1510篇 |
水利工程 | 59篇 |
石油天然气 | 1122篇 |
武器工业 | 204篇 |
无线电 | 2966篇 |
一般工业技术 | 3831篇 |
冶金工业 | 687篇 |
原子能技术 | 1637篇 |
自动化技术 | 633篇 |
出版年
2024年 | 115篇 |
2023年 | 941篇 |
2022年 | 1885篇 |
2021年 | 2204篇 |
2020年 | 1494篇 |
2019年 | 1343篇 |
2018年 | 1154篇 |
2017年 | 1300篇 |
2016年 | 1244篇 |
2015年 | 1127篇 |
2014年 | 1853篇 |
2013年 | 2259篇 |
2012年 | 1924篇 |
2011年 | 2922篇 |
2010年 | 2055篇 |
2009年 | 1872篇 |
2008年 | 1668篇 |
2007年 | 1664篇 |
2006年 | 1320篇 |
2005年 | 976篇 |
2004年 | 813篇 |
2003年 | 682篇 |
2002年 | 603篇 |
2001年 | 531篇 |
2000年 | 389篇 |
1999年 | 236篇 |
1998年 | 274篇 |
1997年 | 200篇 |
1996年 | 152篇 |
1995年 | 96篇 |
1994年 | 91篇 |
1993年 | 66篇 |
1992年 | 73篇 |
1991年 | 67篇 |
1990年 | 47篇 |
1989年 | 43篇 |
1988年 | 25篇 |
1987年 | 25篇 |
1986年 | 26篇 |
1985年 | 32篇 |
1984年 | 23篇 |
1983年 | 12篇 |
1982年 | 18篇 |
1981年 | 5篇 |
1980年 | 16篇 |
1979年 | 5篇 |
1978年 | 4篇 |
1977年 | 5篇 |
1959年 | 11篇 |
1951年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
ZOU Xiao-hua 《数字社区&智能家居》2008,(28)
本文在研究入侵检测技术和免疫学原理的基础上,分析了免疫系统的工作机理,将其和入侵检测系统的工作原理进行了详细比较,并在研究当前各种人工免疫算法的基础上,建立了一个新的基于人工免疫的入侵检测模型框架,实现了当前智能化入侵检测系统所要求的自学习、自适应、分布式和可扩展功能,具有一定的现实意义。 相似文献
62.
E. Zhulkova N. Ilyasova A. Kupriyanov A. Plastinin 《Optical Memory & Neural Networks》2008,17(2):152-156
The presented technology of leukocytes determination upon blood preparation images uses the image representation in HSL (Hue,
Saturation, Lightness) color space. The results of experimental research of the technology quality depending on various distortions
on model and real images are described.
The text was submitted by the authors in English. 相似文献
63.
Jovanović I Ugrenović S Antić S Stefanović N Mihailović D 《Microscopy research and technique》2007,70(7):617-627
Psammoma bodies (PBs) are one of many choroids plexus aging changes. The aim of our research was to perform the quantification of PBs' presence in human choroids plexus stroma, as well as to evaluate the characteristics of choroids plexus stroma in cases in which PBs were present. Afterwards, the observations of the histochemical analysis would be confirmed by immunohistochemical analysis. Choroid plexuses of 30 cadavers were used for the histochemical and, choroids plexuses of 15 cadavers in which PBs' presence was confirmed during the histochemical analysis, were used as material for the immunohistochemical analysis. Light microscopy, histochemical, immunohistochemical, and morphometric method were applied during the study. Classification of the cases was performed by cluster analysis. We observed increase of choroids plexus PBs' presence during the aging process. But this increase is not linear. Their presence is the largest in the second cluster that is younger than the third and older than the first. Nuclear morphometric parameters of the stroma in these cases showed that the cellular composition in this cluster is different than in other two and, that contain larger number of lymphoid cells. Immunohistochemical analysis showed PBs' positive reaction on vimentin, CD45R0, and LCA markers, while in their vicinity, as well as inside them, numerous T-cells were observed. So, the presence of CD45R0 and LCA-positive T cells, PBs' positive reaction on the same markers, indirectly connect these cells with PBs' formation process. 相似文献
64.
65.
水煤浆添加剂的研究进展 总被引:15,自引:0,他引:15
随着世界原油资源的日渐减少及燃煤污染的日趋严重,水煤浆作为一种新型的环保型煤基流体燃料日益受到人们的重视。从70年代至今,国内外学都研究过多种添加剂,目前制浆用添加剂主要分为阴离子表面活性和非离子表面活性剂两大类,但高效、价廉、适用性广的添加剂为数并不多。 相似文献
66.
Uri Cohen 《Journal of Electronic Materials》1977,6(6):607-643
Electrodeposition of both epitaxial and polycrystalline continuous films of dense, coherent, and well-adherent silicon coatings
was achieved from molten fluorides. A dissolving Si anode and an operating temperature of about 750 C were utilized. Silicon
electrocrystallization epitaxy (ECE) produced films with the (111) orientation on Si substrates of the same orientation. The
unintentionally doped films were of p-type character with a resistivity in the range 0.05 - 0.10 Ω-cm. Polycrystalline Si
films were similarly electroplated onto various polycrystalline metal substrates. Uniform coherent, and well-adherent coatings
with grain diameters as large as 40 – 50 μm were obtained. The useful rate of electrodeposition of Si could be significantly
increased by the application of an alternating square wave pulse (ASWP)2technique. Cathodic current pulses as high as 300 mA/cm2 (growth rate of about 5 μm/min) were demonstrated. The cathodic current efficiencies, for all modes of growth, were about
70 – 100%. The effects of the various operating parameters, and some prospective applications to the fabrication of solar
cells, are discussed.
This was paper A-6 in the 18th Annual Electronic Materials Conference, Salt Lake City, June 23–25, 1976. 相似文献
67.
Hortolà P 《Microscopy research and technique》2012,75(8):1007-1011
The aboriginal use of reed and bone as raw materials for knives and daggers, respectively, has been well-documented ethnographically in some geographical areas of Melanesia. Because of the significant role that these weapons played in inter- and intra-ethnic aggression, they can potentially have retained smears from the contact with human blood. To carry out a guiding low-vacuum scanning electron microscopy (SEM) study of specific interest to ethnography, the outsides of a fragment of stalk of giant cane (Arundo donax) and tibial diaphysis of domestic sheep (Ovis aries) were smeared with peripheral human blood. No biological specimen preparation was applied to the samples. After just over 1 month, bloodstain boundaries and their neighboring inner areas were examined via secondary electrons by a variable-pressure SEM (VP-SEM) working in low-vacuum mode. On both substrates, bloodstains exhibited micro-scales. No janocyte (erythrocyte negative replica) was observed in the examined areas. However, erythrocytes were seen crowded together as grain-shaped corpuscles in the smear on reed, and several hecatocytes (moon-like shaped erythrocytes) were evidenced in the smear on bone. The results of this study suggest that a VP-SEM working in low-vacuum mode can be used fruitfully to detect blood remains in medium-sized reed and bone antique aboriginal artifacts. This procedure can prospectively help to ethnographic museum curators and aboriginal-art surveyors as an easy guiding test in the valuation of antique traditional weapons prior to acquisition, when the real use of a piece has been claimed by the supplier. 相似文献
68.
Jun-Qiu Jiang Kun Wang Xue-Xuan Peng Qing-Liang Zhao Yun-Shu Zhang Xiu-Dong Zhou 《哈尔滨工业大学学报(英文版)》2013,20(4):1-6
This paper compared the degradation efficiency of sludge organic matters and electric-production by two typical microbial fuel cells——dual-chamber microbial fuel cell(DMFC)and single chamber air cathode microbial fuel cell(SAMFC),and the variations of sludge protein,polysaccharide and ammonia nitrogen within the systems were also investigated.The results showed that the concentration of sludge soluble chemical oxygen demand,protein and carbohydrate of DMFC are higher than these of SAMFC during the systems operation,while DMFC can achieve a better ammonia nitrogen removal than SAMFC.Under the same operation condition,the stable voltage output of DMFC and SAMFC is 0.61 V and 0.37 V;the maximum power density of DMFC and SAMFC is 2.79 W/m3and 1.25 W/m3;TCOD removal efficiency of DMFC and SAMFC is 34.14%and 28.63%for 12 d,respectively.Meanwhile,DMFC has a higher coulomb efficiency than SAMFC,but both are less than5%.The results showed that DMFC present a better performance on sludge degradation and electric-production. 相似文献
69.
反向选择模型是人工免疫系统中的经典模型,但存在训练代价高、覆盖率低的问题.危险理论模型是人工免疫系统中新引进的模型,在降低训练代价,提高覆盖率上具有优势.建立人工免疫危险理论模型必须解决的关键问题之一是:在保持人工免疫系统自适应特征的前提下,设计人工抗原提呈细胞.本文从抗原提呈细胞的生物学原理出发,设计了人工免疫系统中的人工抗原提呈细胞,给出单个人工抗原提呈细胞的结构、细胞上Toll样受体的结构,以及人工抗原提呈细胞群体的结构;设计了人工抗原提呈细胞群体的生命周期.初步的实验结果证明所设计的人工抗原提呈细胞具有自适应发现恶意软件的能力. 相似文献
70.
采用DS2786B芯片,设计并实现了一款基于S3C2440A处理器的手持式分析诊断仪电池电量计模块。介绍了该模块的硬件电路设计,以及基于WindowsCE5.0操作系统的驱动程序和应用程序的开发。实验结果表明,该模块工作稳定可靠,能精确地测量电池电量并实时在用户界面显示,在嵌入式便携设备中有很好的应用前景。 相似文献