全文获取类型
收费全文 | 1447篇 |
免费 | 103篇 |
国内免费 | 3篇 |
学科分类
工业技术 | 1553篇 |
出版年
2024年 | 5篇 |
2023年 | 18篇 |
2022年 | 16篇 |
2021年 | 84篇 |
2020年 | 39篇 |
2019年 | 45篇 |
2018年 | 46篇 |
2017年 | 46篇 |
2016年 | 44篇 |
2015年 | 45篇 |
2014年 | 68篇 |
2013年 | 107篇 |
2012年 | 84篇 |
2011年 | 97篇 |
2010年 | 69篇 |
2009年 | 76篇 |
2008年 | 62篇 |
2007年 | 45篇 |
2006年 | 53篇 |
2005年 | 45篇 |
2004年 | 40篇 |
2003年 | 36篇 |
2002年 | 25篇 |
2001年 | 23篇 |
2000年 | 18篇 |
1999年 | 30篇 |
1998年 | 33篇 |
1997年 | 32篇 |
1996年 | 24篇 |
1995年 | 31篇 |
1994年 | 27篇 |
1993年 | 15篇 |
1991年 | 6篇 |
1990年 | 8篇 |
1989年 | 13篇 |
1988年 | 6篇 |
1987年 | 6篇 |
1986年 | 8篇 |
1985年 | 9篇 |
1984年 | 9篇 |
1983年 | 6篇 |
1982年 | 11篇 |
1981年 | 4篇 |
1978年 | 3篇 |
1976年 | 6篇 |
1975年 | 4篇 |
1974年 | 3篇 |
1969年 | 6篇 |
1968年 | 2篇 |
1966年 | 2篇 |
排序方式: 共有1553条查询结果,搜索用时 15 毫秒
1.
Andrade R. G. S. A. de Oliveira A. E. Guerra V. G. 《Theoretical Foundations of Chemical Engineering》2022,56(4):504-512
Theoretical Foundations of Chemical Engineering - The corona onset voltage is an important operating parameter in the electrostatic precipitation of nanoparticulate, however, its experimental... 相似文献
2.
3.
4.
5.
Bloomfield R.E. Guerra S. Miller A. Masera M. Weinstock C.B. 《Security & Privacy, IEEE》2006,4(3):66-68
Critical systems are aptly named - from electric power to water and gas to the telephone system and the Internet, they're all critical to some aspect of our daily lives. We're a networked society and as such, it's important to both know whether critical systems are trustworthy and be able to communicate, review, and debate the level of trust achieved in them. In the safety domain, explicit safety cases are increasingly required by law, regulations, and standards. In this article, we outline what a small, international group of experts, spanning various disciplines in safety, security, reliability, and critical infrastructure, been doing with the International Working Group on Assurance Cases (for Security), what we hope to achieve, and where we go next. 相似文献
6.
A Symbolic Pole/Zero Extraction Methodology Based on Analysis of Circuit Time-Constants 总被引:1,自引:0,他引:1
O. Guerra J. D. Rodríguez-García F. V. Fernández A. Rodríguez-Vázquez 《Analog Integrated Circuits and Signal Processing》2002,31(2):101-118
This paper introduces a methodology for symbolic pole/zero extraction based on the formulation of the time-constant matrix of the circuits. This methodology incorporates approximation techniques specifically devoted to achieve an optimum trade-off between accuracy and complexity of the symbolic root expressions. The capability to efficiently handle even large circuits will be demonstrated through several practical circuits. 相似文献
7.
A systems approach is introduced and applied to the development of expressive and communicative action of infants in the first year of life. In this approach, expressive and communicative actions are organized, as part of cooperative systems with other elements of the infants' physiology, cognition, behavior, and social environment. A systems approach presumes that order arises dynamically as a result of the interaction between the cooperating elements that are changing asynchronously, rather than as the result of centrally coordinated developmental change that is synchronous across domains. The systems approach further assumes that the control parameter responsible for eliciting developmental change may be different depending on age, context, and task. It offers a means to understand previously unexplained developmental phenomena: the appearance of mature forms of expression before mature functon has been achieved, the asynchronous rates of development of communicative-action components, discontinuous developmental shifts arising from continuous processes, and the process by which adults influence communicative development. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
8.
N Ferrara G Longobardi N Guerra A Nicolino D Acanfora G Furgi L Odierna R Rosiello F Rengo 《Canadian Metallurgical Quarterly》1996,34(1-2):37-41
We prospectively studied 10 patients with stable exertional ischaemia, selected from a larger group of patients referred for suspected coronary artery disease or to detect residual ischaemia after myocardial infarction, to evaluate pharmacokinetic changes during chronic treatment with gallopamil and its correlation with clinical efficacy in patients with coronary artery disease. Our study consisted of a 1-week run-in single-blind placebo treatment and a 4-week single-blind gallopamil treatment. At the end of the run-in period patients underwent two different exercise tests, the first 2 hours and the second 7 hours after placebo administration. During active treatment all patients underwent two different exercise tests, the first 2 hours and the second 7 hours after gallopamil (50 mg) administration on the 1st and 28th days of gallopamil therapy. On the same days in eight of the patients we evaluated gallopamil pharmacokinetic changes. Our data revealed a rapid increase of unchanged gallopamil and its metabolite (norgallopamil) in the plasma, and a peak concentration of these substances about 2 hour after oral administration on both the 1st and 28th day of observation. Moreover, our results demonstrated an increase between the first and 28th day of treatment in peak concentration of unchanged gallopamil in the plasma, and of AUC 0-infinity and AUC o-c values during chronic treatment with gallopamil. Our clinical data showed an improvement in exercise results during gallopamil therapy related to increased concentration of the drug. 相似文献
9.
PURPOSE: Little has been written regarding the ultrasound imaging features that might allow prediction of fetal viability in abdominal pregnancies. Toward this goal, we present our experience with a series of 11 abdominal pregnancies. MATERIALS AND METHODS: From 1981 to 1993, 11 patients presented to Universidad Catolica, Santiago, and Universidad de Austral, Valdivia, Chile, with third trimester abdominal pregnancies. Five had complete ultrasound examinations, and these five patients were managed expectantly. The other six women presented as acute abdominal emergencies and underwent emergent surgery. RESULTS: Four of five fetuses that survived had a complete placental attachment to the uterus, and one surviving neonate had a partial attachment of the placenta to the uterus. Three fetuses died prior to delivery, and all three had a complete mesenteric placental attachment. Two died in the early neonatal period. One had a complete uterine placental attachment, and the other had a partial attachment. CONCLUSIONS: The survival rate of abdominal pregnancies may be better than is generally believed. Placental attachment to the uterus appears to be a factor related to fetal survival and maternal morbidity. More cases are necessary to determine the feasibility of managing women with abdominal pregnancies expectantly. 相似文献
10.
Sherman Elisabeth M. S.; Strauss Esther; Spellacy Frank; Hunter Michael 《Canadian Metallurgical Quarterly》1995,7(4):440
A 3-factor solution of the Wechsler Adult Intelligence Scale—Revised (WAIS—R; Wechsler, 1981) in 260 adults with suspected head injury suggested relatively good construct validity for the factors, based on correlations with neuropsychological tests purported to measure similar abilities. The Verbal Comprehension factor was related to verbal ability, verbal memory, and executive functioning. The Perceptual Organization factor, although measuring primarily visual–spatial perception and visual constructional ability, was related to visual–spatial memory, visual attention, and executive functioning. The Freedom From Distractibility factor was correlated with two attention measures and was not associated with memory measures. Its association with executive functioning was inconsistent. The findings are discussed in terms of the multidimensional nature of neuropsychological tests and WAIS—R factors. (PsycINFO Database Record (c) 2011 APA, all rights reserved) 相似文献