全文获取类型
收费全文 | 81篇 |
免费 | 0篇 |
国内免费 | 1篇 |
学科分类
工业技术 | 82篇 |
出版年
2019年 | 3篇 |
2014年 | 4篇 |
2013年 | 1篇 |
2012年 | 4篇 |
2011年 | 1篇 |
2010年 | 5篇 |
2009年 | 2篇 |
2008年 | 1篇 |
2006年 | 2篇 |
2005年 | 2篇 |
2004年 | 1篇 |
2003年 | 2篇 |
2001年 | 1篇 |
1999年 | 2篇 |
1998年 | 9篇 |
1997年 | 4篇 |
1996年 | 1篇 |
1995年 | 3篇 |
1994年 | 5篇 |
1993年 | 5篇 |
1991年 | 2篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1983年 | 1篇 |
1982年 | 3篇 |
1977年 | 1篇 |
1976年 | 5篇 |
1973年 | 1篇 |
1971年 | 1篇 |
1963年 | 1篇 |
排序方式: 共有82条查询结果,搜索用时 296 毫秒
11.
Housing policy in the US reflects its general approach to economic and social problems. Among all western democracies, the US relies most on private market forces to provide housing for its population. American housing policy emphasises bolstering market forces and minimising assistance for the poor. Despite its significant achievements (for example, two out of every three American households now owns its dwelling), the US is now facing a severe housing crisis, not only for the poor, but for a sizeable portion of the troubled middle class. To guarantee every American an opportunity to live in decent, safe and affordable housing, the US has to change national priorities and spend more on housing. But it also must spend better: reduce development costs, eliminate bureaucratic waste, and target assistance more efficiently. Following a review of past and current housing programmes, we outline a progressive housing policy agenda and then discuss the political obstacles and opportunities that confront such an ambitious plan. 相似文献
12.
PO Wennberg W Mui D Wunch EA Kort DR Blake EL Atlas GW Santoni SC Wofsy GS Diskin S Jeong ML Fischer 《Environmental science & technology》2012,46(17):9282-9289
We use historical and new atmospheric trace gas observations to refine the estimated source of methane (CH(4)) emitted into California's South Coast Air Basin (the larger Los Angeles metropolitan region). Referenced to the California Air Resources Board (CARB) CO emissions inventory, total CH(4) emissions are 0.44 ± 0.15 Tg each year. To investigate the possible contribution of fossil fuel emissions, we use ambient air observations of methane (CH(4)), ethane (C(2)H(6)), and carbon monoxide (CO), together with measured C(2)H(6) to CH(4) enhancement ratios in the Los Angeles natural gas supply. The observed atmospheric C(2)H(6) to CH(4) ratio during the ARCTAS (2008) and CalNex (2010) aircraft campaigns is similar to the ratio of these gases in the natural gas supplied to the basin during both these campaigns. Thus, at the upper limit (assuming that the only major source of atmospheric C(2)H(6) is fugitive emissions from the natural gas infrastructure) these data are consistent with the attribution of most (0.39 ± 0.15 Tg yr(-1)) of the excess CH(4) in the basin to uncombusted losses from the natural gas system (approximately 2.5-6% of natural gas delivered to basin customers). However, there are other sources of C(2)H(6) in the region. In particular, emissions of C(2)H(6) (and CH(4)) from natural gas seeps as well as those associated with petroleum production, both of which are poorly known, will reduce the inferred contribution of the natural gas infrastructure to the total CH(4) emissions, potentially significantly. This study highlights both the value and challenges associated with the use of ethane as a tracer for fugitive emissions from the natural gas production and distribution system. 相似文献
13.
In this article members of the Digital Signal Processing (DSP) Technical Committee (TC) report recent breakthroughs in signal processing fundamentals that have happened in the last two decades. These breakthroughs include various advances and extensions from old techniques to new techniques. For example, signal processing techniques have moved from single-rate to multirate processing, from time-invariant to adaptive processing, from frequency-domain (the traditional Fourier transform, as we know it) to time-frequency analysis, and from linear to non-linear signal processing. Recent developments in these areas have not only renovated the theory of digital signal processing, they have also resulted in new tools that find applications in various domains. For instance, multirate signal processing has triggered recent advances in modem technology and speech/audio coding; adaptive filtering has made echo cancellation and noise suppression possible; time-frequency analysis has found its way into various applications in radar and medical signal processing; and non-linear processing has made engineers rethink various problems in speech recognition and image analysis. This article provides an extensive list of highlights from these recent developments. 相似文献
14.
Hohlstein Leigh Anne; Smith Gregory T.; Atlas Jana G. 《Canadian Metallurgical Quarterly》1998,10(1):49
Instruments for measuring learned expectations for reinforcement from eating and from dieting and thinness were constructed and validated. Five eating reinforcement expectancies and 1 dieting-thinness reinforcement expectancy were identified and their factor structure replicated on an independent sample. The expectancy that dieting and thinness lead to overgeneralized self-improvement characterized bulimia nervosa and anorexia nervosa patients and correlated with dieting behavior in a general sample. Expectancies for negative reinforcement from eating (e.g., eating helps manage negative affect) characterized bulimic but not anorexic individuals and were correlated with indexes of restraint plus disinhibition in a general sample. Positive reinforcement expectancies (e.g., eating is pleasurable and rewarding) were unrelated to disinhibited eating, but anorexic patients expected significantly less positive reinforcement from eating than did bulimic patients or controls. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
15.
The empirical mode decomposition (EMD) has seen widespread use for analysis of nonlinear and nonstationary time-series. Despite some practical success, it lacks a firm theoretical foundation. This work addresses two important theoretical properties. The original EMD algorithm is slightly modified, in a way that facilitates this analysis. For periodic, band-limited, signals the convergence and time scale separation of the algorithm are proved. 相似文献
16.
Machine Intelligence Research - The convergence analysis of MaxMin-SOMO algorithm is presented. The SOM-based optimization (SOMO) is an optimization algorithm based on the self-organizing map (SOM)... 相似文献
17.
18.
<正>四川峨胜水泥股份有限公司地处四川省峨眉山市九里镇,交通非常便利,距厂区十余公里处有着丰富的石灰石矿资源,可开发前景广阔。四川峨胜水泥股份有限公司(以下简称峨胜水泥)是四川省内专业 相似文献
19.
O Wiser M Trus A Hernández E Renstr?m S Barg P Rorsman D Atlas 《Canadian Metallurgical Quarterly》1999,96(1):248-253
Although N- and P-type Ca2+ channels predominant in fast-secreting systems, Lc-type Ca2+ channels (C-class) can play a similar role in certain secretory cells and synapses. For example, in retinal bipolar cells, Ca2+ entry through the Lc channels triggers ultrafast exocytosis, and in pancreatic beta-cells, evoked secretion is highly sensitive to Ca2+. These findings suggest that a rapidly release pool of vesicles colocalizes with the Ca2+ channels to allow high Ca2+ concentration and a tight coupling of the Lc channels at the release site. In binding studies, we show that the Lc channel is physically associated with synaptotagmin (p65) and the soluble N-ethylmaleimide-sensitive attachment proteins receptors: syntaxin and synaptosomal-associated protein of 25 kDa. Soluble N-ethylmaleimide-sensitive attachent proteins receptors coexpressed in Xenopus oocytes along with the Lc channel modify the kinetic properties of the channel. The modulatory action of syntaxin can be overcome by coexpressing p65, where at a certain ratio of p65/syntaxin, the channel regains its unaltered kinetic parameters. The cytosolic region of the channel, Lc753-893, separating repeats II-III of its alpha1C subunit, interacts with p65 and "pulls" down native p65 from rat brain membranes. Lc753-893 injected into single insulin-secreting beta-cell, inhibits secretion in response to channel opening, but not in response to photolysis of caged Ca2+, nor does it affect Ca2+ current. These results suggest that Lc753-893 competes with the endogenous channel for the synaptic proteins and disrupts the spatial coupling with the secretory apparatus. The molecular organization of the Lc channel and the secretory machinery into a multiprotein complex (named excitosome) appears to be essential for an effective depolarization evoked exocytosis. 相似文献
20.
Fetzer E. McMillin L.M. Tobin D. Aumann H.H. Gunson M.R. McMillan W.W. Hagan D.E. Hofstadter M.D. Yoe J. Whiteman D.N. Barnes J.E. Bennartz R. Vomel H. Walden V. Newchurch M. Minnett P.J. Atlas R. Schmidlin F. Olsen E.T. Goldberg M.D. Sisong Zhou HanJung Ding Smith W.L. Revercomb H. 《Geoscience and Remote Sensing, IEEE Transactions on》2003,41(2):418-431
The Atmospheric Infrared Sounder/Advanced Microwave Sounding Unit/Humidity Sounder for Brazil (AIRS/AMSU/HSB) instrument suite onboard Aqua observes infrared and microwave radiances twice daily over most of the planet. AIRS offers unprecedented radiometric accuracy and signal to noise throughout the thermal infrared. Observations from the combined suite of AIRS, AMSU, and HSB are processed into retrievals of atmospheric parameters such as temperature, water vapor, and trace gases under all but the cloudiest conditions. A more limited retrieval set based on the microwave radiances is obtained under heavy cloud cover. Before measurements and retrievals from AIRS/AMSU/HSB instruments can be fully utilized they must be compared with the best possible in situ and other ancillary "truth" observations. Validation is the process of estimating the measurement and retrieval uncertainties through comparison with a set of correlative data of known uncertainties. The ultimate goal of the validation effort is retrieved product uncertainties constrained to those of radiosondes: tropospheric rms uncertainties of 1.0 degC over a 1-km layer for temperature, and 10% over 2-km layers for water vapor. This paper describes the data sources and approaches to be used for validation of the AIRS/AMSU/HSB instrument suite, including validation of the forward models necessary for calculating observed radiances, validation of the observed radiances themselves, and validation of products retrieved from the observed radiances. Constraint of the AIRS product uncertainties to within the claimed specification of 1 K/1 km over well-instrumented regions is feasible within 12 months of launch, but global validation of all AIRS/AMSU/HSB products may require considerably more time due to the novelty and complexity of this dataset and the sparsity of some types of correlative observations. 相似文献