全文获取类型
收费全文 | 2706篇 |
免费 | 201篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 19篇 |
综合类 | 1篇 |
化学工业 | 765篇 |
金属工艺 | 44篇 |
机械仪表 | 74篇 |
建筑科学 | 103篇 |
矿业工程 | 11篇 |
能源动力 | 93篇 |
轻工业 | 421篇 |
水利工程 | 20篇 |
石油天然气 | 10篇 |
无线电 | 180篇 |
一般工业技术 | 397篇 |
冶金工业 | 171篇 |
原子能技术 | 25篇 |
自动化技术 | 576篇 |
出版年
2024年 | 8篇 |
2023年 | 43篇 |
2022年 | 108篇 |
2021年 | 145篇 |
2020年 | 89篇 |
2019年 | 101篇 |
2018年 | 113篇 |
2017年 | 100篇 |
2016年 | 137篇 |
2015年 | 89篇 |
2014年 | 151篇 |
2013年 | 235篇 |
2012年 | 192篇 |
2011年 | 194篇 |
2010年 | 145篇 |
2009年 | 134篇 |
2008年 | 129篇 |
2007年 | 120篇 |
2006年 | 76篇 |
2005年 | 65篇 |
2004年 | 72篇 |
2003年 | 46篇 |
2002年 | 57篇 |
2001年 | 31篇 |
2000年 | 27篇 |
1999年 | 26篇 |
1998年 | 38篇 |
1997年 | 35篇 |
1996年 | 17篇 |
1995年 | 28篇 |
1994年 | 21篇 |
1993年 | 15篇 |
1992年 | 12篇 |
1991年 | 10篇 |
1990年 | 11篇 |
1989年 | 11篇 |
1988年 | 8篇 |
1987年 | 12篇 |
1986年 | 13篇 |
1985年 | 10篇 |
1984年 | 5篇 |
1983年 | 5篇 |
1982年 | 4篇 |
1981年 | 5篇 |
1979年 | 2篇 |
1977年 | 2篇 |
1976年 | 5篇 |
1971年 | 2篇 |
1969年 | 1篇 |
1941年 | 1篇 |
排序方式: 共有2910条查询结果,搜索用时 0 毫秒
991.
Discusses repression in bilingual analyses, including repressed memories, transference, and dreams, as well as the whole associative process. As certain memories are more accessible in one language than the other, repression for bilingual individuals may be partly a function of linguistic accessibility. The concept of repression will therefore need to be reassessed in the context of these observations. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
992.
Carlos Jiménez-Ruiz Marc Miravitlles Víctor Sobradillo Rafael Gabriel José Luis Viejo Juan Fernando Masa Lorenzo Fernández-Fau Carlos Villasante 《Nicotine & tobacco research》2004,6(4):649-653
Between 15% and 20% of smokers develop chronic obstructive pulmonary disease (COPD). The aim of the present study was to determine which characteristics of smoking, particularly the Fagerstr?m Test for Nicotine Dependence (FTND) score, were associated with the risk of developing COPD. Data from the IBERPOC epidemiological study were analyzed. IBERPOC was a multicenter epidemiological study including 4035 individuals aged 40-69 years, 1023 (25%) of whom were active smokers. We analyzed the association between smoking characteristics--such as the cumulative consumption of tobacco, FTND score, and expired-air carbon monoxide levels--and the diagnosis of COPD. Among the smokers, 153 (15%) were diagnosed with COPD. A cumulative tobacco consumption of more than 30 pack-years (OR=4.24, 95% CI=2.83-6.36) and the FTND score (OR=1.11, 95% CI=1.02-1.21, for each point increase) were significantly associated with the diagnosis of COPD in the model obtained by logistic regression analysis with the full sample of smokers. Cumulative consumption of tobacco was associated with the diagnosis of COPD. For each point increase in the FTND score, the probability of a smoker developing COPD increased by 11%. 相似文献
993.
Various methods for the measurement and classification of safety performance at construction sites, e.g., timing relative to the moment of accident, data collection method, safety effectiveness criterion, performance measure, and frequency and severity of the measured event, are analyzed. The effectiveness of the various methods and the extent of their use at construction sites are examined. Attributes that are investigated include efficiency, reliability, and validity and diagnostic capacity of the measure in order to identify the cause for success or failure, respectively, of the safety program at a site. The data for the study were collected through questionnaires which were addressed to the largest construction companies in the United States. The most effective and the most widely employed measurement methods were lost‐day cases, doctor's cases, and cost of accidents. The least effective and most limited in use were the no‐injury cases. 相似文献
994.
A total of 180 sound teeth extracted from people living mainly in Northern Israel and some in the center of the country, aged 14-75 years, were analysed by graphite furnace atomic absorption spectrophotometer. The average lead level in teeth roots ranged between 1.61-25.72 micrograms/g dry root, according to the donor's age. This low level was measured in all the regions which were checked, with no significant differences between them, despite differences in levels of motor traffic rates. Based on the low lead level in teeth, we assume that no further reduction in the lead level in gasoline is needed, as long as motorization rate or gasoline consumption does not change significantly. 相似文献
995.
Sjogren's syndrome is an autoimmune disease characterized by exocrine gland destruction and manifested by parotid, submandibular and lacrimal gland infection. We report a case with recurrent severe parotid gland infections. The sialographic and CT findings are presented. 相似文献
996.
997.
998.
Graphs are used commonly as a basic modeling tool in areas such as project management, production scheduling, line balancing, business process reengineering, and software visualization. An important problem in the area of graph drawing is to minimize arc crossings in a multi-layer hierarchical digraph. Existing solution methods for this problem are based on simple ordering rules for single layers that may lead to inferior drawings. This article first introduces an extensive review of relevant work previously published in this area. Then a tabu search implementation is presented that seeks high-quality drawings by means of an intensification phase that finds a local optimum according to an insertion mechanism and two levels of diversification. Computational experiments with 200 graphs with up to 30 nodes per layer and up to 30 layers are presented to assess the merit of the method. 相似文献
999.
L Fr?lich D Blum-Degen HG Bernstein S Engelsberger J Humrich S Laufer D Muschner A Thalheimer A Türk S Hoyer R Z?chling KW Boissl K Jellinger P Riederer 《Canadian Metallurgical Quarterly》1998,105(4-5):423-438
The search for the causes of neurodegenerative disorders is a major theme in brain research. Acquired disturbances of several aspects of cellular metabolism appear pathologically important in sporadic Alzheimer's disease (SDAT). Among these brain glucose utilisation is reduced in the early stages of the disease and the regulatory enzymes important for glucose metabolism are reduced. In the brain, insulin, insulin-like growth factors and their receptors regulate glucose metabolism and promote neuronal growth. To detect changes in the functional activity of the brain insulin neuromodulatory system of SDAT patients, we determined the concentrations of insulin and c-peptide as well as insulin receptor binding and IGF-I receptor binding in several regions of postmortem brain cortex during aging and Alzheimer's disease. Additionally, we performed immunohistochemical staining with antibodies against insulin in neocortical brain areas in SDAT and controls. We show for the first time that insulin and c-peptide concentration in the brain are correlated and decrease with aging, as do brain insulin receptor densities. Weak insulin-immunoreactivity could be demonstrated histochemically in pyramidal neurons of controls, whereas in SDAT a stronger insulin-immunoreactivity was found. On a biochemical level, insulin and c-peptide levels were reduced compared to middle-aged controls, but were unchanged compared to age-matched controls. Brain insulin receptor densities in SDAT were decreased compared to middle-aged controls, but increased in comparison to age-matched controls. IGF-I receptor densities were unchanged in aging and in SDAT. Tyrosine kinase activity, a signal transduction mechanism common to both receptor systems, was reduced in SDAT in comparison to middle-aged and age-matched control groups. These data are consistent with a neurotrophic role of insulin in the human brain and a disturbance of insulin signal transduction in SDAT brain and favor the hypothesis that insulin dependent functions may be of pathogenetic relevance in sporadic SDAT. 相似文献
1000.
André Nieuwland Jeffrey Kang Om Prakash Gangwal Ramanathan Sethuraman Natalino Busá Kees Goossens Rafael Peset Llopis Paul Lippens 《Design Automation for Embedded Systems》2002,7(3):233-270
The key issue in the design of Systems-on-a-Chip (SoC) is to trade-off efficiency against flexibility, and time to market versus cost. Current deep submicron processing technologiesenable integration of multiple software programmable processors (e.g., CPUs,DSPs) and dedicated hardware components into a single cost-efficient IC. Ourtop-down design methodology with various abstraction levels helps designingthese ICs in a reasonable amount of time. This methodology starts with a high-levelexecutable specification, and converges towards a silicon implementation.A major task in the design process is to ensure that all components (hardwareand software) communicate with each other correctly. In this article, we tacklethis problem in the context of the signal processing domain in two ways: wepropose a modular, flexible, and scalable heterogeneous multi-processor architecturetemplate based on distributed shared memory, and we present an efficient andtransparent protocol for communication and (re)configuration. The protocolimplementations have been incorporated in libraries, which allows quick traversalof the various abstraction levels, so enabling incremental design. The designdecisions to be taken at each abstraction level are evaluated by means of(co-)simulation. Prototyping is used too, to verify the system's functionalcorrectness. The effectiveness of our approach is illustrated by a designcase of a multi-standard video and image codec.He currently works with Magma Design Automation. E-mail: 相似文献