全文获取类型
收费全文 | 3081篇 |
免费 | 99篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 61篇 |
综合类 | 4篇 |
化学工业 | 1025篇 |
金属工艺 | 54篇 |
机械仪表 | 36篇 |
建筑科学 | 193篇 |
矿业工程 | 30篇 |
能源动力 | 32篇 |
轻工业 | 389篇 |
水利工程 | 10篇 |
石油天然气 | 1篇 |
无线电 | 154篇 |
一般工业技术 | 461篇 |
冶金工业 | 289篇 |
原子能技术 | 30篇 |
自动化技术 | 412篇 |
出版年
2022年 | 27篇 |
2021年 | 41篇 |
2020年 | 33篇 |
2019年 | 32篇 |
2018年 | 43篇 |
2017年 | 40篇 |
2016年 | 68篇 |
2015年 | 87篇 |
2014年 | 77篇 |
2013年 | 115篇 |
2012年 | 115篇 |
2011年 | 158篇 |
2010年 | 111篇 |
2009年 | 111篇 |
2008年 | 117篇 |
2007年 | 141篇 |
2006年 | 121篇 |
2005年 | 113篇 |
2004年 | 105篇 |
2003年 | 76篇 |
2002年 | 73篇 |
2001年 | 59篇 |
2000年 | 57篇 |
1999年 | 57篇 |
1998年 | 76篇 |
1997年 | 60篇 |
1996年 | 60篇 |
1995年 | 57篇 |
1994年 | 67篇 |
1993年 | 42篇 |
1992年 | 45篇 |
1991年 | 44篇 |
1990年 | 28篇 |
1989年 | 42篇 |
1987年 | 30篇 |
1986年 | 33篇 |
1985年 | 39篇 |
1984年 | 41篇 |
1983年 | 32篇 |
1982年 | 32篇 |
1981年 | 30篇 |
1980年 | 31篇 |
1978年 | 28篇 |
1977年 | 30篇 |
1976年 | 30篇 |
1975年 | 41篇 |
1974年 | 22篇 |
1973年 | 30篇 |
1972年 | 24篇 |
1970年 | 30篇 |
排序方式: 共有3181条查询结果,搜索用时 15 毫秒
1.
Daniela Fogli Antonio Piccinno Stefan Carmien Gerhard Fischer 《Behaviour & Information Technology》2020,39(1):27-46
ABSTRACTThe digital age of the future is ‘not out there to be discovered’, but it needs to be ‘designed’. The design challenge has to address questions about how we want to live, work, and learn (as individuals and as communities) and what we value and appreciate, e.g.: reflecting on quality of life and creating inclusive societies. An overriding design trade-off for the digital age is whether new developments will increase the digital divide or will create more inclusive societies. Sustaining inclusive societies means allowing people of all ages and all abilities to exploit information technologies for personally meaningful activities. Meta-design fosters the design of socio-technical environments that end-user developers can modify and evolve at use time to improve their quality of life and favour their inclusion in the society. This paper describes three case studies in the domain of assistive technologies in which end users themselves cannot act as end-user developers, but someone else (e.g.: a caregiver or a clinician) must accept this role requiring multi-tiered architectures. The design trade-offs and requirements for meta-design identified in the context of the case studies and other researchers’ projects are described to inform the development of future socio-technical environments focused on social inclusion. 相似文献
2.
3.
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
4.
5.
6.
7.
IC Wegner RR Dawirs C Grond G Teuchert-Noodt 《Canadian Metallurgical Quarterly》1997,60(22):2005-2011
The epithelium of the digestive system mucosa consists of a highly dynamic cell population. The conditions under which mitotic activity in the gastrointestinal epithelium is regulated is as yet poorly understood. Nevertheless, it is assumed that some biogenic amines might be involved. Having demonstrated that dopaminergic cells occur in the stomach of gerbils (Meriones unguiculatus), in the present study we examined the influence of dopamine antagonist haloperidol on the proliferation of epithelial cells in the mucosa of the stomach. Proliferating cells were detected immunocytochemically and quantified after in-vivo labeling with 5-bromo-2'-desoxyuridine in both haloperidol- and saline-treated animals. The results show that acute doses of haloperidol significantly increases the proliferation rate in the pyloric mucosa, suggesting that dopamine plays a probable modulatory role in the regulation of mitotic activity. These findings are discussed with regard to the role of paraneurons in regulating epithelial mitosis. 相似文献
8.
9.
Heinrich Heydt Philipp Eisenbarth Karin Feith Klaus Urgast Gerhard Maas Manfred Regitz 《Israel journal of chemistry》1986,27(1):96-104
Amino-substituted cyclopropenylium salts ( 11a,b ) react with diazomethyl compounds ( 12a-i ) in dichloromethane or acetonitrile in the presence of a base (ethyldiisopropylamine, 1,5-diazabicyclo[4.3.0] non-5-ene) to form 4-aminopyridazines ( 13a-i ) specifically. The reaction is interpreted in terms of an initial electrophilic diazoalkane substitution to give diazomethylcyclopropenes ( 11 + 12 → 14 ) which undergo a [1.5]-cyclisation to form the betaines 16 which, in turn, isomerise with opening of the bridging bond to give the aminopyridazines 13 . In a similar manner, the tris[amino] cyclopropenylium salts 8a,b and 10a-c are converted to the 3,4,5-tris[amino]-pyridazines ( 21a-k ) by treatment with diazomethyl compounds ( 12a, c-f ). 相似文献
10.
RD Wegner I Henrichs H Joenje T Schroeder-Kurth 《Canadian Metallurgical Quarterly》1996,50(6):479-482
The clinical and cytogenetic data of the first patient proven to belong to the fifth Fanconi anemia complementation group are described. The Turkish boy presented with psychomotoric retardation, growth retardation, retarded bone age, brachycephaly, hypotelorism, epicanthus, syndactyly, brachydactyly, renal dystopia, and cryptorchism. In addition, an asymmetrical skeletal anomaly was seen with a double distal phalanx of the left thumb and hypoplasia of the right thumb. Typical hematological features of the disorder developed, at the age of 2.5 years, about 1 year after diagnosis. Cytogenetic studies confirmed the clinical diagnosis and revealed a spontaneous chromosomal instability and hypersensitivity to the cross-linking agents diepoxybutane and Trenimon. The findings in the patient, who is considered to be the standard for the fifth Fanconi anemia complementation group, are compared with data reported for other patients affected with Fanconi anemia. 相似文献