全文获取类型
| 收费全文 | 2824篇 |
| 免费 | 188篇 |
| 国内免费 | 164篇 |
专业分类
| 电工技术 | 116篇 |
| 综合类 | 176篇 |
| 化学工业 | 413篇 |
| 金属工艺 | 207篇 |
| 机械仪表 | 144篇 |
| 建筑科学 | 109篇 |
| 矿业工程 | 36篇 |
| 能源动力 | 61篇 |
| 轻工业 | 168篇 |
| 水利工程 | 83篇 |
| 石油天然气 | 114篇 |
| 武器工业 | 5篇 |
| 无线电 | 303篇 |
| 一般工业技术 | 748篇 |
| 冶金工业 | 136篇 |
| 原子能技术 | 76篇 |
| 自动化技术 | 281篇 |
出版年
| 2025年 | 67篇 |
| 2024年 | 123篇 |
| 2023年 | 198篇 |
| 2022年 | 216篇 |
| 2021年 | 212篇 |
| 2020年 | 120篇 |
| 2019年 | 70篇 |
| 2018年 | 79篇 |
| 2017年 | 46篇 |
| 2016年 | 48篇 |
| 2015年 | 69篇 |
| 2014年 | 79篇 |
| 2013年 | 101篇 |
| 2012年 | 236篇 |
| 2011年 | 273篇 |
| 2010年 | 78篇 |
| 2009年 | 58篇 |
| 2008年 | 189篇 |
| 2007年 | 154篇 |
| 2006年 | 167篇 |
| 2005年 | 129篇 |
| 2004年 | 59篇 |
| 2003年 | 45篇 |
| 2002年 | 49篇 |
| 2001年 | 35篇 |
| 2000年 | 36篇 |
| 1999年 | 34篇 |
| 1998年 | 34篇 |
| 1997年 | 26篇 |
| 1996年 | 43篇 |
| 1995年 | 20篇 |
| 1994年 | 15篇 |
| 1993年 | 14篇 |
| 1992年 | 11篇 |
| 1991年 | 12篇 |
| 1990年 | 2篇 |
| 1989年 | 4篇 |
| 1988年 | 3篇 |
| 1987年 | 3篇 |
| 1986年 | 3篇 |
| 1985年 | 1篇 |
| 1983年 | 2篇 |
| 1982年 | 12篇 |
| 1980年 | 1篇 |
排序方式： 共有3176条查询结果，搜索用时 15 毫秒
61.
62.
Detection of intracellular Zn(2+) has gained great attention because of its biological significances. Here we show the fabrication of silica-coated S(2-)-enriched Mn-doped ZnS quantum dots (SiO(2)-S-Mn-ZnS QDs) by enriching S(2-) with a silica shell on the surface of Mn-doped ZnS QDs via a sol-gel process for imaging intracellular Zn(2+) ions. The developed probe gave a good linearity for the calibration plot (the recovered PL intensity of the SiO(2)-S-Mn-ZnS QDs against the concentration of Zn(2+) from 0.3 to 15.0 μM), excellent reproducibility (1.2% relative standard deviation for 11 replicate measurements of Zn(2+) at 3 μM), and low detection limit (3s; 80 nM Zn(2+)). The SiO(2)-S-Mn-ZnS QDs showed negligible cytotoxicity, good sensitivity, and selectivity for Zn(2+) in a photoluminescence turn-on mode, being a promising probe for photoluminescence imaging of intracellular Zn(2+). 相似文献
63.
64.
65.
针对小动物磁共振成像分析仪,进行双柱型永磁小磁体的设计,要求静磁场强度为0.5 T,磁场不均匀度小于25×10-6.考虑磁路漏磁情况及磁阻现象,采用磁路设计中常用的磁路方法,进行永磁磁体结构的初始设计;利用有限元方法对初始的模型进行磁场数值分析;改变匀场环的形状和尺寸,观察空隙中磁力线的走向改变,分析匀场环的改变对成像区磁场均匀度的影响.利用Ansys有限元软件对匀场环的尺寸进行了优化计算,当匀场环内径大约为外径的1/3时,成像区不均匀度提高一个数量级.结果表明永磁磁体的磁路设计方法和有限元数值计算合理,可以满足成像要求. 相似文献
66.
Cell-cell interactions are essential for multicellular organisms, playing important roles in their development, function, and immunity. Herein a bottom-up strategy to construct self-assembled DNA nanostructures is reported, consisting of multivalent, bispecific, cell-targeting aptamers to specifically induce cell-cell interactions. Various DNA nanoscaffolds are rationally designed to assemble aptamers with different valencies and flexibilities, and their cellular binding capabilities are tested. Multivalent aptamers, assembled on more rigid scaffolds, display higher binding activities. Further, multivalent bispecific aptamer fusion molecules are constructed based on this configuration, and successfully link two types of cells. Using cell-targeting aptamers, the presented strategy eliminates the need to chemically modify cell surfaces and offers excellent cell specificity, binding efficiency, and stability. This proof-of-concept study establishes that multivalent bispecific aptamers linked on DNA-nanoscaffolds can mediate cellular engagement, which could lead to their use in directing or guiding cell-cell interactions in many biological events. 相似文献
67.
68.
Crosstalk has become one of the most critical concerns in very deep sub-micron era. This paper deals with the problem of crosstalk mitigation at both methodological and algorithmic levels. Noting that intermediate operations between global routing and detailed routing are very effective in crosstalk estimation and reduction, the authors propose to incorporate several intermediate steps that are separated in traditional design flow into an integrated routing resource assignment stage, so that the operations could easily cooperate to fully exert their power on crosstalk reduction. An efficient priority-based heuristic algorithm is developed, which works slice by slice. Crosstalk avoidance, and many other aspects that are critical in routing practice including congestion, vias, layer preference, etc., are taken into account. A track reservation strategy is adopted in the algorithm framework to compensate the undesired effects caused by sequential routing. Experimental results on a series of ISPD98 and industrial benchmarks show that the proposed approach is able to reduce capacitive crosstalk by about 70% on average without compromising completion ratio compared with a previously reported graph based algorithm, demonstrating the advantages of the approach. 相似文献
69.
开发了一个用于二值图象边界平滑跟踪的一个算法。使用这个算法能去掉或修正某些可能是虚假的干扰点。这些点是二值图象边界一个或一组沿特定链码方向的凸点或凹点。重复地使用这个算法,直到边界不含有这些点。这个算法能有效地使用在二值图象的模式识别与机器人视觉的预处理中。 相似文献
70.
A mathematical model, including electromagnetic field equation, fluid flow equation, and temperature field equation, was established for the simulation of the electroslag remelting process. The distribution of temperature field was obtained by solving this model. The relationship between the local solidification time and the interdendritic spacing during the ingot solidification process was established, which has been regarded as a criterion for the evaluation of the quality of crystallization. For a crucible of 950 mm in diameter, the local solidification time is more than 1 h at the center of the ingot with the longest interdendritic spacing, whereas it is the shortest at the edge of the ingot according to the calculated results. The model can be used to understand the ESR process and to predict the ingot quality. 相似文献