全文获取类型
收费全文 | 925篇 |
免费 | 123篇 |
国内免费 | 53篇 |
专业分类
电工技术 | 86篇 |
综合类 | 55篇 |
化学工业 | 161篇 |
金属工艺 | 54篇 |
机械仪表 | 65篇 |
建筑科学 | 86篇 |
矿业工程 | 34篇 |
能源动力 | 34篇 |
轻工业 | 77篇 |
水利工程 | 27篇 |
石油天然气 | 67篇 |
武器工业 | 12篇 |
无线电 | 118篇 |
一般工业技术 | 83篇 |
冶金工业 | 54篇 |
原子能技术 | 10篇 |
自动化技术 | 78篇 |
出版年
2024年 | 15篇 |
2023年 | 33篇 |
2022年 | 55篇 |
2021年 | 85篇 |
2020年 | 55篇 |
2019年 | 34篇 |
2018年 | 39篇 |
2017年 | 47篇 |
2016年 | 42篇 |
2015年 | 31篇 |
2014年 | 55篇 |
2013年 | 53篇 |
2012年 | 70篇 |
2011年 | 49篇 |
2010年 | 62篇 |
2009年 | 37篇 |
2008年 | 42篇 |
2007年 | 56篇 |
2006年 | 50篇 |
2005年 | 38篇 |
2004年 | 19篇 |
2003年 | 20篇 |
2002年 | 19篇 |
2001年 | 8篇 |
2000年 | 22篇 |
1999年 | 17篇 |
1998年 | 11篇 |
1997年 | 4篇 |
1996年 | 8篇 |
1995年 | 4篇 |
1994年 | 5篇 |
1992年 | 5篇 |
1991年 | 2篇 |
1990年 | 3篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1980年 | 1篇 |
排序方式: 共有1101条查询结果,搜索用时 16 毫秒
1.
Abstract The whole DNA of soybean was implanted into four varieties of wheat of Zhongyu5, Huaiyin 9628, Wenyou 1, Jimai 5 respectively via ion-beam mediation. There were 5 plantsobtained whose protein content was higher than 18.5%, the highest one was 21.44%. There were 3plants obtained whose protein content was lower than 11.5%, the lowest one was 10.96%. We cansee that the whole DNA of soybean transformed into wheat via ion beam implantation can inducethe increase in wheat protein content dramatically. The result also shows that the transformationefficiency of different gene types of wheat receptor varies greatly that the implanting time has acertain effect on the efficiency of transformation. 相似文献
2.
针对边缘检测中阈值很难确定导致不能准确提取背景边缘信息的问题,提出一种改进的基于边缘信息车流量检测方法。该方法预先对路况边缘图像作削顶处理获取一个恰当的阈值,从而可以准确地提取背景边缘信息;且在车辆计数过程中,结合固定窗法和浮动窗法二者的优点,设计一种新的浮动窗法进行车辆计数。实验结果表明,该方法在实时性、检测速度、正确率等方面得到很大的改进,能够在不同环境下进行正确有效地车流量检测。 相似文献
3.
电晕放电是高压电力工程及航空航天领域研究的重点及难点问题;为研究尖端导体电晕放电的辐射特点,设计了电晕放电试验模拟系统;利用测试系统及天线在微波暗室内进行了不同测试距离、不同放电电压及不同尖端导体长度条件下的试验;通过对试验数据的分析可知,电晕放电辐射信号呈衰减振荡模式;电晕放电脉冲重复率随着充电电压的增大而增加;天线接收的辐射信号能量与测试距离成反比;随着充电电压的增加,信号辐射功率呈增加趋势;试验研究结果为输变电工程、航空航天装备的电磁环境分析提供参考。 相似文献
4.
Exploring the wild birds’ migration data for the disease spread study of H5N1: a clustering and association approach 总被引:1,自引:0,他引:1
Mingjie Tang Yuanchun Zhou Jinyan Li Weihang Wang Peng Cui Yuanseng Hou Ze Luo Jianhui Li Fuming Lei Baoping Yan 《Knowledge and Information Systems》2011,27(2):227-251
Knowledge about the wetland use of migratory bird species during the annual life circle is very interesting to biologists,
as it is critically important in many decision-making processes such as for conservation site construction and avian influenza
control. The raw data of the habitat areas and the migration routes are usually in large scale and with high complexity when
they are determined by high-tech GPS satellite telemetry. In this paper, we convert these biological problems into computational
studies and introduce efficient algorithms for the data analysis. Our key idea is the concept of hierarchical clustering for
migration habitat localizations, and the notion of association rules for the discovery of migration routes from the scattered
location points in the GIS. One of our clustering results is a tree structure, specially called spatial-tree, which is an
illusive map depicting the breeding and wintering home range of bar-headed geese. A related result to this observation is
an association pattern that reveals a high possibility that bar-headed geese’s potential autumn migration routes are likely
between the breeding sites in the Qinghai Lake, China and the wintering sites in Tibet river valley. Given the susceptibility
of geese to spread H5N1, and on the basis of the chronology and the rates of the bar-headed geese migration movements, we
can conjecture that bar-headed geese play an important role in the spread of the H5N1 virus at a regional scale in Qinghai-Tibetan
Plateau. 相似文献
5.
胡命杰 《计算机与数字工程》2006,34(6):151-153
液货船作业过程仿真软件是计算机仿真技术在航海领域的典型应用,目前已成为培训、考核广大船员的一种重要手段。其中,化学品船作业仿真软件是液货船作业过程仿真软件的核心组成部分。化学品船作业仿真软件成功地将面向对象的方法融入到仿真模型的建立上。软件开发过程符合现代软件工程理论基础。在软件开发过程中采用了ActiveX,数据库,多线程技术等保证仿真效果的实现。 相似文献
6.
7.
8.
Swarna Mahadevan Kenelm Kwong Mingjie Lu Elizabeth Kelly Belal Chami Yevgeniy Romin Sho Fujisawa Katia Manova Malcolm A. S. Moore Hans Zoellner 《International journal of molecular sciences》2022,23(14)
We recently described cell-projection pumping as a mechanism transferring cytoplasm between cells. The uptake of fibroblast cytoplasm by co-cultured SAOS-2 osteosarcoma cells changes SAOS-2 morphology and increases cell migration and proliferation, as seen by single-cell tracking and in FACS separated SAOS-2 from co-cultures. Morphological changes in SAOS-2 seen by single cell tracking are consistent with previous observations in fixed monolayers of SAOS-2 co-cultures. Notably, earlier studies with fixed co-cultures were limited by the absence of a quantitative method for identifying sub-populations of co-cultured cells, or for quantitating transfer relative to control populations of SAOS-2 or fibroblasts cultured alone. We now overcome that limitation by a novel Cartesian plot analysis that identifies individual co-cultured cells as belonging to one of five distinct cell populations, and also gives numerical measure of similarity to control cell populations. We verified the utility of the method by first confirming the previously established relationship between SAOS-2 morphology and uptake of fibroblast contents, and also demonstrated similar effects in other cancer cell lines including from melanomas, and cancers of the ovary and colon. The method was extended to examine global DNA methylation, and while there was no clear effect on SAOS-2 DNA methylation, co-cultured fibroblasts had greatly reduced DNA methylation, similar to cancer associated fibroblasts. 相似文献
9.
Chao Li Yuanyuan Zhang Jie Ju Futao Cheng Mingjie Liu Lei Jiang Yanlei Yu 《Advanced functional materials》2012,22(4):760-763
An in situ fully light‐driven switching of superhydrophobic adhesion is demonstrated based on simply spin‐coating a hydrophobic azo‐polymer on an optimized micro‐nanopost arrayed silicon substrate. Furthermore, the detailed designing principles are discussed, which might shed light on efficient exploitation of superhydrophobic liquid/solid interfaces for smart microfluidic control. 相似文献
10.
计算机接警指挥调度系统的设计 总被引:1,自引:0,他引:1
介绍分局级公安指挥和接处警系统的设计思想和实现方法.该系统利用语音卡得到报警信息,以自动拨号方式同相关单位建立联系,通过电话召开临时会议,帮助指挥人员迅速、准确地作出决策和部署警力. 相似文献