首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   2045篇
  免费   67篇
  国内免费   10篇
电工技术   22篇
化学工业   349篇
金属工艺   56篇
机械仪表   99篇
建筑科学   55篇
矿业工程   4篇
能源动力   95篇
轻工业   100篇
水利工程   6篇
石油天然气   12篇
无线电   250篇
一般工业技术   470篇
冶金工业   270篇
原子能技术   61篇
自动化技术   273篇
  2023年   31篇
  2022年   40篇
  2021年   57篇
  2020年   49篇
  2019年   42篇
  2018年   46篇
  2017年   50篇
  2016年   50篇
  2015年   30篇
  2014年   72篇
  2013年   141篇
  2012年   86篇
  2011年   110篇
  2010年   102篇
  2009年   83篇
  2008年   86篇
  2007年   72篇
  2006年   66篇
  2005年   36篇
  2004年   39篇
  2003年   43篇
  2002年   39篇
  2001年   29篇
  2000年   33篇
  1999年   22篇
  1998年   43篇
  1997年   44篇
  1996年   34篇
  1995年   40篇
  1994年   34篇
  1993年   31篇
  1992年   28篇
  1991年   31篇
  1990年   34篇
  1989年   20篇
  1988年   23篇
  1987年   22篇
  1986年   17篇
  1985年   21篇
  1984年   27篇
  1983年   21篇
  1982年   28篇
  1981年   23篇
  1980年   15篇
  1979年   20篇
  1978年   13篇
  1977年   19篇
  1976年   31篇
  1975年   10篇
  1973年   10篇
排序方式: 共有2122条查询结果,搜索用时 15 毫秒
1.
Aromatic and functional polymers with processibility derived from biobased starting materials are prerequisite considering sustainable society. Poly(2,5-benzimidazole)s are rigid-rod polymers to show ultrahigh thermal stability such as flame retardance, while usually suffer from poor solubility. Here, poly(benzimidazole-co-amide)s are synthesized from two biobased monomers, 3,4-diaminobenzoic acid and a semirigid comonomer, 4-aminohydrocinnamic acid. The copolymers with an amide composition of 80 mol% and higher are soluble in widely used polar solvents to fabricate the films keeping high flame retardance, which is comparable with popular high-performance polymers such as aromatic polyimides, polyetheretherketone, polyphenylene sulfide, etc.  相似文献   
2.
Multimedia Tools and Applications - A secret sharing scheme partitions a secret into a set of shares and distributes them among the eligible participants, with each participant receiving one share...  相似文献   
3.
The Journal of Supercomputing - Currently, all online social networks (OSNs) are considered to follow a power-law distribution. In this paper, the degree distribution for multiple OSNs has been...  相似文献   
4.
5.
Proficiency on underlying mechanism of rubber-metal adhesion has been increased significantly in the last few decades. Researchers have investigated the effect of various ingredients, such as hexamethoxymethyl melamine, resorcinol, cobalt stearate, and silica, on rubber-metal interface. The role of each ingredient on rubber-metal interfacial adhesion is still a subject of scrutiny. In this article, a typical belt skim compound of truck radial tire is selected and the effect of each adhesive ingredient on adhesion strength is explored. Out of these ingredients, the effect of cobalt stearate is found noteworthy. It has improved adhesion strength by 12% (without aging) and by 11% (humid-aged), respectively, over control compound. For detailed understanding of the effect of cobalt stearate on adhesion, scanning electron microscopy and energy dispersive spectroscopy are utilized to ascertain the rubber coverage and distribution of elements. X-ray photoelectron spectroscopy results helped us to understand the impact of CuXS layer depth on rubber-metal adhesion. The depth profile of the CuXS layer was found to be one of the dominant factors of rubber-metal adhesion retention. Thus, this study has made an attempt to find the impact of different adhesive ingredients on the formation of CuXS layer depth at rubber-metal interface and establish a correlation with adhesion strength simultaneously.  相似文献   
6.
A faceted initiation site is observed in Ti-6242 alloy for both the cyclic and static-loading test conditions. In this experimental study, the crystallographic orientation of the facets has been determined using the electron backscattered diffraction (EBSD) technique in conjunction with the quantitative tilt fractography in a scanning electron microscope (SEM). Quantitative tilt fractography analysis has been used to determine the spatial orientation of fracture facets. The results indicate that the normal-fatigue (no-dwell) fracture facets are oriented at ∼5 deg with respect to the basal plane; the dwell-fatigue fracture facets are oriented at ∼10 to 15 deg with respect to the basal plane and the static-loading fracture facets are oriented at ∼20 deg with respect to the basal plane. These crystallographic orientation determinations of the fracture facets at the crack-initiation site can be used to obtain an idea about the type of loading that produced them.  相似文献   
7.
8.
9.
Family nursing, always a component of nursing, has been recently receiving increased attention through publications, educational programs, clinical practice settings and family nursing research. Nurses are in the best position to assist families experiencing the illness of a loved one, but often lack the skills and confidence necessary to assist with the psychosocial needs. The purpose of this paper is to describe the development and implementation of a family nursing program within a large, tertiary care facility. The program's evaluation is ongoing but early outcomes indicate that day-to-day nursing practice has been positively influenced and improved job satisfaction may result.  相似文献   
10.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号