全文获取类型
收费全文 | 2424篇 |
免费 | 130篇 |
国内免费 | 8篇 |
专业分类
电工技术 | 79篇 |
综合类 | 24篇 |
化学工业 | 452篇 |
金属工艺 | 83篇 |
机械仪表 | 22篇 |
建筑科学 | 64篇 |
矿业工程 | 26篇 |
能源动力 | 30篇 |
轻工业 | 822篇 |
水利工程 | 10篇 |
石油天然气 | 8篇 |
无线电 | 115篇 |
一般工业技术 | 378篇 |
冶金工业 | 84篇 |
原子能技术 | 16篇 |
自动化技术 | 349篇 |
出版年
2023年 | 26篇 |
2022年 | 36篇 |
2021年 | 92篇 |
2020年 | 49篇 |
2019年 | 49篇 |
2018年 | 85篇 |
2017年 | 62篇 |
2016年 | 92篇 |
2015年 | 67篇 |
2014年 | 94篇 |
2013年 | 119篇 |
2012年 | 96篇 |
2011年 | 95篇 |
2010年 | 104篇 |
2009年 | 97篇 |
2008年 | 97篇 |
2007年 | 97篇 |
2006年 | 63篇 |
2005年 | 47篇 |
2004年 | 40篇 |
2003年 | 41篇 |
2002年 | 44篇 |
2001年 | 28篇 |
2000年 | 19篇 |
1999年 | 25篇 |
1998年 | 41篇 |
1997年 | 30篇 |
1996年 | 17篇 |
1995年 | 15篇 |
1994年 | 20篇 |
1992年 | 14篇 |
1991年 | 14篇 |
1990年 | 16篇 |
1943年 | 18篇 |
1942年 | 14篇 |
1936年 | 18篇 |
1934年 | 16篇 |
1931年 | 13篇 |
1930年 | 15篇 |
1929年 | 13篇 |
1928年 | 15篇 |
1925年 | 19篇 |
1924年 | 26篇 |
1923年 | 19篇 |
1918年 | 28篇 |
1917年 | 30篇 |
1916年 | 26篇 |
1915年 | 34篇 |
1911年 | 14篇 |
1910年 | 15篇 |
排序方式: 共有2562条查询结果,搜索用时 218 毫秒
1.
2.
A contact layer element for large deformations 总被引:1,自引:0,他引:1
3.
Paul Geoerg Florian Berchtold Steven Gwynne Karen Boyce Stefan Holl Anja Hofmann 《火与材料》2019,43(7):759-781
To quantify the evacuation process, evacuation practitioners use engineering egress data describing the occupant movement characteristics. These data are typically based to young and fit populations. However, the movement abilities of occupants who might be involved in evacuations are becoming more variable—with the building populations of today typically including increasing numbers of individuals: with impairments or who are otherwise elderly or generally less mobile. Thus, there will be an increasing proportion of building occupants with reduced ability to egress. For safe evacuation, there is therefore a need to provide valid engineering egress data considering pedestrians with disabilities. Gwynne and Boyce recently compiled a series of data sets related to the evacuation process to support practitioner activities in the chapter Engineering Data in the SFPE Handbook of Fire Protection Engineering. This paper supplements these data sets by providing information on and presenting data obtained from additional research related to the premovement and horizontal movement of participants with physical‐, cognitive‐, or age‐related disabilities. The aim is to provide an overview of currently available data sets related to, and key factors affecting the egress performance of, mixed ability populations which could be used to guide fire safety engineering decisions in the context of building design. 相似文献
4.
Dr. Vlastimil Jirasko Dr. Nils-Alexander Lakomek Dr. Susanne Penzel Dr. Marie-Laure Fogeron Prof. Dr. Ralf Bartenschlager Prof. Dr. Beat H. Meier Dr. Anja Böckmann 《Chembiochem : a European journal of chemical biology》2020,21(10):1453-1460
Proton-detected 100 kHz magic-angle-spinning (MAS) solid-state NMR is an emerging analysis method for proteins with only hundreds of microgram quantities, and thus allows structural investigation of eukaryotic membrane proteins. This is the case for the cell-free synthesized hepatitis C virus (HCV) nonstructural membrane protein 4B (NS4B). We demonstrate NS4B sample optimization using fast reconstitution schemes that enable lipid-environment screening directly by NMR. 2D spectra and relaxation properties guide the choice of the best sample preparation to record 2D 1H-detected 1H,15N and 3D 1H,13C,15N correlation experiments with linewidths and sensitivity suitable to initiate sequential assignments. Amino-acid-selectively labeled NS4B can be readily obtained using cell-free synthesis, opening the door to combinatorial labeling approaches which should enable structural studies. 相似文献
5.
Semi‐Markovian processes (SMP) serve as a versatile means to model various traffic types generated by sources or superposed
from links in ATM networks. An efficient discrete time analysis method is proposed for SMP/G/1 queueing systems to evaluate
ATM switches with non‐renewal input. Some basic results are derived for the autocorrelation function of semi‐Markovian processes
and for the effect of state space reduction on autocorrelation, which show how to represent correlated traffic with given
characteristic by an adequate SMP model of limited size.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
6.
二维多孔数控钻床加工路径的生成及优化 总被引:7,自引:0,他引:7
印刷电路板 PCB的加工是二维多孔数控钻的典型。实践表明加工同一零件不同的走刀路径其长度相差极大。为提高生产率 ,应使刀具的走刀路径尽量短 ,这其实是大型的 TSP问题。本文提出了几种路径的生成方法 ,分析了各自的适用场合。并用实例验证所提出的路径生成方法可极大地提高实际钻孔的加工效率。 相似文献
7.
8.
9.
10.
A necessary and sufficient criterion is presented under which the property of positivity carry over from the data set to rational quadratic spline interpolants. The criterion can always be satisfied if the occuring parameters are properly chosen. 相似文献