全文获取类型
收费全文 | 6696篇 |
免费 | 528篇 |
国内免费 | 201篇 |
专业分类
电工技术 | 453篇 |
综合类 | 503篇 |
化学工业 | 328篇 |
金属工艺 | 98篇 |
机械仪表 | 498篇 |
建筑科学 | 157篇 |
矿业工程 | 91篇 |
能源动力 | 54篇 |
轻工业 | 211篇 |
水利工程 | 33篇 |
石油天然气 | 52篇 |
武器工业 | 54篇 |
无线电 | 2137篇 |
一般工业技术 | 509篇 |
冶金工业 | 112篇 |
原子能技术 | 51篇 |
自动化技术 | 2084篇 |
出版年
2023年 | 39篇 |
2022年 | 73篇 |
2021年 | 133篇 |
2020年 | 127篇 |
2019年 | 103篇 |
2018年 | 111篇 |
2017年 | 144篇 |
2016年 | 153篇 |
2015年 | 227篇 |
2014年 | 440篇 |
2013年 | 328篇 |
2012年 | 600篇 |
2011年 | 521篇 |
2010年 | 435篇 |
2009年 | 366篇 |
2008年 | 418篇 |
2007年 | 465篇 |
2006年 | 406篇 |
2005年 | 350篇 |
2004年 | 312篇 |
2003年 | 293篇 |
2002年 | 210篇 |
2001年 | 177篇 |
2000年 | 159篇 |
1999年 | 136篇 |
1998年 | 85篇 |
1997年 | 102篇 |
1996年 | 91篇 |
1995年 | 75篇 |
1994年 | 50篇 |
1993年 | 58篇 |
1992年 | 28篇 |
1991年 | 36篇 |
1990年 | 14篇 |
1989年 | 18篇 |
1988年 | 11篇 |
1987年 | 6篇 |
1986年 | 4篇 |
1985年 | 18篇 |
1984年 | 29篇 |
1983年 | 27篇 |
1982年 | 14篇 |
1976年 | 3篇 |
1966年 | 2篇 |
1964年 | 4篇 |
1961年 | 2篇 |
1960年 | 2篇 |
1959年 | 3篇 |
1957年 | 3篇 |
1956年 | 2篇 |
排序方式: 共有7425条查询结果,搜索用时 15 毫秒
1.
为了解决医院耗材数量多、种类复杂导致的科室耗材管理琐碎繁杂问题。本文提出基于人工智能调度及智能柜分类管理的医院科室耗材精细化管理方法。利用大数据方法建立医院科室耗材数据库,分段拟合控制数据库信息,通过空间资源优化分配方法重组数据,构造医院科室耗材的智能柜,智能分类识别医院科室耗材,提取医院科室耗材信息的统计特征量,规则化调度和自动更新医院科室耗材管理信息,实现医院科室耗材的精细化管理和评估。仿真结果表明,本文方法可实现医院科室耗材精细化管理,分类性能较好,精细化水平较高。 相似文献
2.
This study was conducted to investigate the virtual display effects on direct interaction performance metrics such as accuracy, task completion time, and comfort. Eighteen participants performed tapping (pointing) tasks in the coronal plane by directly reaching for tapping targets at three egocentric distance levels, with three indices of difficulty at each egocentric distance. The position data and severity of cybersickness symptoms were collected with a motion system and a symptom questionnaire, respectively. The results indicated that accuracy was higher with the stereoscopic widescreen display than with the head mounted display. However, no significant differences in task completion time, throughput, and cybersickness were observed between the two VR displays. In addition, increasing the egocentric distance improved accuracy and lengthened the task completion time, whereas increasing the task difficulty lengthened the task completion time but did not affect the accuracy. The findings are important and informative for users in choosing between the two virtual reality displays. Generally, the stereoscopic widescreen display can be recommended for tasks requiring high egocentric distance accuracy in the coronal plane. Furthermore, developers may refer to these findings in designing interfaces that allow a more natural way of interaction for users. 相似文献
3.
Dr. Tjibbe Bosma Dr. Rick Rink Dr. Markus A. Moosmeier Prof. Dr. Gert N. Moll 《Chembiochem : a European journal of chemical biology》2019,20(14):1754-1758
Many therapeutic peptides can still be improved with respect to target specificity, target affinity, resistance to peptidases/proteases, physical stability, and capacity to pass through membranes required for oral delivery. Several modifications can improve the peptides’ properties, in particular those that impose (a) conformational constraint(s). Screening of constrained peptides and the identification of hits is greatly facilitated by the generation of genetically encoded libraries. Recent breakthrough bacterial, phage, and yeast display screening systems of ribosomally synthesized post-translationally constrained peptides, particularly those of lanthipeptides, are earning special attention. Here we provide an overview of display systems for constrained, genetically encoded peptides and indicate prospects of constrained peptide-displaying phage and bacterial systems as such in vivo. 相似文献
4.
博物馆恒湿文物展柜的湿度控制至关重要,为实现展柜的自动恒湿功能,本文基于吸附式空气取水原理,提出了一种将环境水汽自动补充至恒湿文物展柜系统水箱的方法,并搭建了相应的小型空气取水装置,证明了该方法的可行性;同时,构建了传热传质耦合的空气取水装置数学模型,在获取环境温湿度对装置取水量的影响规律后,分析加热功率和吸附床结构对装置单位能耗取水量的影响;此外,为便于装置的后期推广应用,提出了两个基于吸附床高度和直径的量纲为1参数。结果表明:进口空气的温度对取水量影响较小,但进口空气的湿度对取水量影响较明显,取水量随着湿度增加而增加;加热功率存在最优值,单位能耗取水量随着加热功率先增大后减小;在当前几何参数组合下,两个量纲为1参数η=2、β=4时,装置的单位能耗取水量最高。 相似文献
5.
6.
Dr. Emrah Kara Dr. Nis Valentin Nielsen Bergrun Eggertsdottir Dr. Bernd Thiede Dr. Sandip M. Kanse Dr. Geir Åge Løset 《Chembiochem : a European journal of chemical biology》2020,21(13):1875-1884
We describe a novel, easy and efficient combinatorial phage display peptide substrate-mining method to map the substrate specificity of proteases. The peptide library is displayed on the pVII capsid of the M13 bacteriophage, which renders pIII necessary for infectivity and efficient retrieval, in an unmodified state. As capture module, the 3XFLAG was chosen due to its very high binding efficiency to anti-FLAG mAbs and its independency of any post-translational modification. This library was tested with Factor-VII activating protease (WT-FSAP) and its single-nucleotide polymorphism variant Marburg-I (MI)-FSAP. The WT-FSAP results confirmed the previously reported Arg/Lys centered FSAP cleavage site consensus as dominant, as well as reinforcing MI-FSAP as a loss-of-function mutant. Surprisingly, rare substrate clones devoid of basic amino acids were also identified. Indeed one of these peptides was cleaved as free peptide, thus suggesting a broader range of WT-FSAP substrates than previously anticipated. 相似文献
7.
Multiplane displays are capable of displaying 3D scenes with correct focus cues by creating multilayer 2D images in the display volume. Hence, such a 3D display technique could effectively address the accommodation‐vergence conflict (AVC) problem, which is prevalent in augmented reality (AR) displays. In this paper, we review the recent progress on multiplane AR displays based on liquid crystals (LCs) for AR applications. The working principle of multiplane AR displays is illustrated, the electro‐optical properties of the tunable LC devices are investigated and display prototypes are demonstrated. Finally, we discuss the prospects and challenges of multiplane AR displays based on LCs. 相似文献
8.
Paul J. Steiner Matthew A. Bedewitz Angélica V. Medina-Cucurella Sean R. Cutler Timothy A. Whitehead 《American Institute of Chemical Engineers》2020,66(3):e16767
Small-molecule biosensors have major applications in biotechnology and medicine but remain difficult to engineer. Plant hormone receptors represent an attractive platform for engineering such biosensors because their chemically induced dimerization architectures naturally decouple small-molecule sensing and sensor actuation. Rapid biosensor engineering will require quantitative high-throughput screening methods. Here we develop a yeast surface display (YSD) platform for the PYR1/HAB1 abscisic acid sensor of Arabidopsis thaliana. We extensively optimized PYR1 surface display, HAB1 purification, and binding reaction conditions. Our system reproduces previous results with wild-type and engineered receptors, and a mathematical analysis of the PYR1/HAB1 system allows us to infer all binding constants. Critically, we find that a previously engineered PYR1 receptor with altered ligand specificity binds HAB1 with identical affinity, suggesting that substantial reengineering of the PYR1 binding pocket does not compromise sensor actuation. This YSD platform for A. thaliana PYR1/HAB1 will facilitate future biosensor engineering efforts. 相似文献
9.
《Ceramics International》2020,46(5):6276-6283
In this study, novel Eu3+-, Dy3+-, and Sm3+-activated Na3La(VO4)2 phosphors were synthesized using a solid state reaction method. X-ray diffraction analysis results indicated that the Na3La(VO4)2 phosphors had an orthorhombic crystal structure with the Pbc21 space group. There were two different La(1)O8 and La(2)O8 polyhedra with high asymmetry in the crystal structure. Scanning electron microscopy revealed that the product had a sheet morphology with an irregular particle size. Further, the luminescence properties, including the excitation and emission spectra, and luminescence decay curve, were investigated using a fluorescence spectrometer. The results showed that the Na3La(VO4)2 compound was an excellent host for activating the luminescence of Eu3+ (614 nm), Dy3+ (575 nm), and Sm3+ (647 nm) ions. Further, Dy3+/Eu3+ co-doped Na3La(VO4)2 phosphors were exploited, and the energy transfer from Dy3+ to Eu3+ was demonstrated in detail by the photoluminescence excitation, photoluminescence spectra, and luminescent decay curves. The results showed that the energy transfer efficiency from Dy3+ to Eu3+ was highly efficient, and the energy transfer mechanism was dipole–dipole interactions. Finally, tunable emissions from the yellow region of CIE (0.3925, 0.4243) to the red region of CIE (0.6345, 0.3354) could be realized by rationally controlling the Dy3+/Eu3+ concentration ratio. These phosphors may be promising materials for the development of solid-state lighting and display systems. 相似文献
10.
《Displays》2015
We report a screen-printing fabrication process for large area electrowetting display (EWD) devices using polyimide-based materials. The poly(imide siloxane) was selected as hydrophobic insulator layer, and relatively hydrophilic polyimide as grids material. EWD devices that use poly(imide siloxane) as hydrophobic insulator fabricated with conventional methods showed good and reversible electrowetting performance on both single droplet level and device level, which showed its potential application in EWDs. The compatibility of polyimide-based materials (hydrophobic poly(imide siloxane) and hydrophilic polyimide) guarantee the good adhesion between two layers and the capability of printable fabrication. To this end, the hydrophilic grids have been successfully built on hydrophobic layer by screen-printing directly. The resulting EWD devices showed good switch performance and relatively high yield. Compared to conventional method, the polyimide-based materials and method offer the advantages of simple, cheap and fast fabrication, and are especially suitable for large area display fabrication. 相似文献