全文获取类型
收费全文 | 1027篇 |
免费 | 57篇 |
专业分类
电工技术 | 10篇 |
化学工业 | 184篇 |
金属工艺 | 10篇 |
机械仪表 | 24篇 |
建筑科学 | 43篇 |
矿业工程 | 3篇 |
能源动力 | 16篇 |
轻工业 | 204篇 |
水利工程 | 5篇 |
石油天然气 | 2篇 |
无线电 | 55篇 |
一般工业技术 | 151篇 |
冶金工业 | 211篇 |
原子能技术 | 10篇 |
自动化技术 | 156篇 |
出版年
2023年 | 5篇 |
2022年 | 15篇 |
2021年 | 11篇 |
2020年 | 15篇 |
2019年 | 20篇 |
2018年 | 36篇 |
2017年 | 27篇 |
2016年 | 28篇 |
2015年 | 17篇 |
2014年 | 32篇 |
2013年 | 69篇 |
2012年 | 46篇 |
2011年 | 63篇 |
2010年 | 47篇 |
2009年 | 51篇 |
2008年 | 52篇 |
2007年 | 55篇 |
2006年 | 31篇 |
2005年 | 30篇 |
2004年 | 20篇 |
2003年 | 30篇 |
2002年 | 20篇 |
2001年 | 19篇 |
2000年 | 25篇 |
1999年 | 20篇 |
1998年 | 83篇 |
1997年 | 52篇 |
1996年 | 16篇 |
1995年 | 19篇 |
1994年 | 26篇 |
1993年 | 16篇 |
1992年 | 8篇 |
1991年 | 7篇 |
1990年 | 7篇 |
1989年 | 6篇 |
1988年 | 5篇 |
1987年 | 5篇 |
1986年 | 6篇 |
1985年 | 2篇 |
1984年 | 4篇 |
1983年 | 3篇 |
1982年 | 3篇 |
1981年 | 4篇 |
1980年 | 5篇 |
1979年 | 1篇 |
1978年 | 3篇 |
1977年 | 6篇 |
1976年 | 9篇 |
1969年 | 1篇 |
1968年 | 2篇 |
排序方式: 共有1084条查询结果,搜索用时 15 毫秒
81.
82.
Jack A. Neal Betsy Booren Luis Cisneros-Zevallos Rhonda K. Miller Lisa M. Lucia Joseph E. Maxim Alejandro Castillo 《Journal of food science》2010,75(6):S319-S326
Abstract: The use of ionizing radiation for the control of foodborne pathogens and extending the shelf life of fresh iceberg lettuce and fresh spinach has recently been approved by the U.S. Food and Drug Administration. The efficacy of electron beam irradiation for controlling foodborne pathogens has been reported. For this experiment, the effectiveness of electron beam irradiation on the microbiological and sensory characteristics of fresh spinach was studied. Total aerobic plate counts were reduced by 2.6 and 3.2 log CFU/g at 0.7 and 1.4 kGy, respectively. Lactic acid bacteria were reduced at both doses of e-beam but grew slowly over the 35 d of the experiment. Yeasts and molds were not reduced in samples exposed to 0.7 kGy whereas 1.4 kGy significantly reduced microbial counts. Gas compositions (O2 and CO2) were significantly different than controls. Oxygen levels inside the spinach sample bags decreased over time; however, O2 levels did not drop below 1% that can induce anaerobic fermentation. CO2 levels for all treatments increased through day 4; yet 7 d after irradiation, CO2 level differences were not significant in both control and irradiated samples. Irradiation dose did not affect the basic tastes, aromatics, or mouth feels of fresh spinach, however; hardness attributes decreased as irradiated dose increased and slimy attributes of fresh spinach were higher in control samples compared to irradiated samples. 相似文献
83.
An efficient and compact algebraic approach to state estimation observability is proposed. It is based on transferring rows to columns and vice versa in the Jacobian measurement matrix. The proposed methodology provides a unified approach to observability checking, critical measurement identification, determination of observable islands, and selection of pseudo-measurements to restore observability. Additionally, the observability information obtained from a given set of measurements can provide directly the observability obtained from any subset of measurements of the given set. Several examples are used to illustrate the capabilities of the proposed methodology, and results from a large case study are presented to demonstrate the appropriate computational behavior of the proposed algorithms. Finally, some conclusions are drawn. 相似文献
84.
Michael Bynum Anya Castillo Jean-Paul Watson Carl D. Laird 《American Institute of Chemical Engineers》2019,65(7):e16508
While peak shaving is commonly used to reduce power costs, chemical process facilities that can reduce power consumption on demand during emergencies (e.g., extreme weather events) bring additional value through improved resilience. For process facilities to effectively negotiate demand response (DR) contracts and make investment decisions regarding flexibility, they need to quantify their additional value to the grid. We present a grid-centric mixed-integer stochastic programming framework to determine the value of DR for improving grid resilience in place of capital investments that can be cost prohibitive for system operators. We formulate problems using both a linear approximation and a nonlinear alternating current power flow model. Our numerical results with both models demonstrate that DR can be used to reduce the capital investment necessary for resilience, increasing the value that chemical process facilities bring through DR. However, the linearized model often underestimates the amount of DR needed in our case studies. Published 2018. This article is a U.S. Government work and is in the public domain in the USA. AIChE J, 65: e16508, 2019 相似文献
85.
H. Calvo del Castillo J.L. Ruvalcaba M.F. Salinas Nolasco K. Perdigón 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2008,266(10):2311-2315
The coast of Guerrero Negro (Baja California) has been known for a long time by archaeologists for its shipwrecks. Archaeologists are recovering objects that come from sunken Spanish galleons in the colonial period, and reach the American coast in the frontier of the USA with Mexico.An enamelled metallic object was found next to the beach in Guerrero Negro. We have analysed the piece with proton induced X-ray emission (PIXE) and Rutherford backscattering (RBS) in an attempt to establish whether the object could come from one of the colonial shipwrecks and to valuate its cleaning process.Scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry (EDS) have been also performed in three samples taken from the object in order to observe the heterogeneity of the material.The materials found revealed the presence of typical lead-glass enamels from with pigments such as cuprite (red), or lead-tin yellow used in colonial times. The metallic part consisted of brass. As for the cleaning process, the average efficiency considered as the weight% of chlorine removed, was of 83.4% for brass and 100% for enamels. 相似文献
86.
87.
Ronald G. McGarvey Enrique Del Castillo Tom M. Cavalier E. Amine Lehtihet 《Quality and Reliability Engineering International》2002,18(5):395-402
Sequential tolerance control (STC) is a tolerance control methodology used in discrete parts manufacturing. Recently, an adaptive sphere‐fitting method for STC (ASF–STC) was developed to account for potential skewness in manufacturing operations' distributions, a factor not considered in conventional STC. ASF–STC offers significant improvements over conventional STC when such skewness exists. The direction of skewness of an operations' distribution is a necessary input to ASF–STC. Thus, a novel approach to determining the skewness of a distribution for small sample sizes is presented here. ASF–STC has an additional requirement of distribution information for each operation. The beta distribution is an ideal candidate here, as it is very flexible in shape. The literature on four‐parameter beta estimation is very limited, and their performance for small sample sizes is poor. STC was designed for low‐volume production, thus the estimation for small sample sizes is necessary here. This study presents a heuristic, based on the method of moments estimates for a beta distribution, that estimates the four parameters for a beta distribution with small sample size. Several computational results are provided to compare this heuristic to the best‐known procedure, with the heuristic found to perform better for the test problems considered. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
88.
M de Abood Z de Castillo F Guerrero M Espino KL Austin 《Canadian Metallurgical Quarterly》1997,56(5):313-316
Forty-three homozygous (SS) female sickle cell anemic patients with a history of at least one painful crisis per month and desiring a reversible contraceptive were administered DMPA/3 months or Microgynon monthly. A third group of 16 surgically sterilized patients served as control. Patients were followed for 1 year to assess possible effects of the contraceptives on the patients' painful crises. No changes were observed in any of the groups in the hematological parameters. At the end of the study, 70% of the patients receiving DMPA were pain-free and only 16% of those still reporting painful crises rated them as intense. Patients receiving Microgynon also had an amelioration of the painful crises, although at a lower rate; after 12 months, 45.5% still experienced some crises. Although less marked than in the other groups, 50.5% of the control patients also reported an improvement of their painful crisis, which may be a result of closer medical care. 相似文献
89.
We describe the general dependence of the diffusion coefficient associated with the Van der Waals binary mixture on the temperature, number densities, and relative strengths of molecular interaction parameters. The task is facilitated by the fact that for Kac-type intermolecular potentials, in the long-range limit, the diffusion coefficient becomes simply related to the product of a partial compressibility and the curvature of the equilibrium free energy in the space of number densities. Therefore the different kinds of behavior found can be classified according to the scheme of Scott and Van Konynenburg for the global phase diagram of the same model mixture.Paper presented at the Tenth Symposium on Thermophysical Properties, June 20–23, 1988, Gaithersburg, Maryland, U.S.A. 相似文献
90.
Castillo E. Conejo A.J. Pruneda R.E. Solares C. Menendez J.M. 《Power Systems, IEEE Transactions on》2008,23(2):296-305
This paper provides a technique to determine the minimum required measurement set to ensure observability in state estimation even if any meters fail. The technique relies on solving a nonlinear integer programming problem. The proposed procedure is illustrated through a simple example and three case studies based on the IEEE Test Systems. Conclusions are finally drawn. 相似文献