全文获取类型
收费全文 | 219篇 |
免费 | 4篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 7篇 |
化学工业 | 48篇 |
金属工艺 | 2篇 |
机械仪表 | 3篇 |
建筑科学 | 8篇 |
矿业工程 | 6篇 |
轻工业 | 8篇 |
石油天然气 | 6篇 |
无线电 | 16篇 |
一般工业技术 | 23篇 |
冶金工业 | 60篇 |
原子能技术 | 7篇 |
自动化技术 | 30篇 |
出版年
2022年 | 3篇 |
2021年 | 4篇 |
2017年 | 2篇 |
2016年 | 2篇 |
2015年 | 1篇 |
2014年 | 6篇 |
2013年 | 22篇 |
2012年 | 8篇 |
2011年 | 6篇 |
2010年 | 5篇 |
2009年 | 11篇 |
2008年 | 6篇 |
2007年 | 5篇 |
2006年 | 3篇 |
2005年 | 1篇 |
2004年 | 3篇 |
2003年 | 5篇 |
2002年 | 6篇 |
2001年 | 4篇 |
2000年 | 6篇 |
1999年 | 5篇 |
1998年 | 8篇 |
1997年 | 15篇 |
1996年 | 9篇 |
1995年 | 1篇 |
1994年 | 5篇 |
1993年 | 4篇 |
1992年 | 3篇 |
1991年 | 5篇 |
1990年 | 4篇 |
1989年 | 3篇 |
1988年 | 4篇 |
1987年 | 5篇 |
1986年 | 5篇 |
1985年 | 5篇 |
1984年 | 1篇 |
1983年 | 3篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1978年 | 4篇 |
1977年 | 4篇 |
1976年 | 5篇 |
1975年 | 2篇 |
1974年 | 3篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1967年 | 1篇 |
1956年 | 1篇 |
1935年 | 1篇 |
排序方式: 共有224条查询结果,搜索用时 125 毫秒
31.
F.R. Espinoza-Quiones A.N. Mdenes L.P. Thom S.M. Palcio D.E.G. Trigueros A.P. Oliveira N. Szymanski 《Chemical engineering journal (Lausanne, Switzerland : 1996)》2009,150(2-3):316-322
In the present work, the lead phytoaccumulation by living free floating aquatic macrophytes Salvinia auriculata was investigated in a greenhouse. These plants were grown in lead-doped hydroponic solutions forming, as a function of time, six collections of nutrient media, roots and leaves of plants from a batch system. The synchrotron X-ray radiation fluorescence technique was used in order to determine element concentrations in the nutrient media, dry roots and aerial parts of plant. The aquatic plant-based lead removal data were described by using a non-structural kinetic model. According to the experimental data, both adsorption and bioaccumulation mechanism are present and a competition between the phosphorus macronutrient and lead for plant growth was observed, when great concentration of lead in roots is present. The non-structural kinetic models have shown good agreement with the lead uptake experimental data in all the investigated cases. The results of living macrophytes S. auriculata-based-metal bioaccumulation kinetic parameters can be used in artificial wetlands to predict the heavy metal removal dynamics from wastewaters. 相似文献
32.
Cobbold RN Davis MA Rice DH Szymanski M Tarr PI Besser TE Hancock DD 《Journal of food protection》2008,71(5):1023-1027
A survey for Shiga toxigenic Escherichia coli in raw milk and beef was conducted within a defined geographic region of the United States. Prevalence rates based on detection of Shiga toxin gene (stx) were 36% for retail beef, 23% for beef carcasses, and 21% for raw milk samples, which were significantly higher than were Shiga toxigenic E. coli isolation rates of 7.5, 5.8, and 3.2%, respectively. Seasonal prevalence differences were significant for stx positivity among ground beef and milk samples. Distribution of stx subtypes among isolates varied according to sample type, with stx1 predominating in milk, stx2 on carcasses, and the combination of both stx1 and stx2 in beef. Ancillary virulence markers eae and ehx were evident in 23 and 15% of isolates, respectively. Pulsed-field gel electrophoresis demonstrated associations between food isolates and sympatric bovine fecal, and human clinical isolates. These data demonstrate that non-O157 Shiga toxigenic E. coli is present in the food chain in the Pacific Northwest, and its risk to health warrants critical assessment. 相似文献
33.
34.
Ofwat used comparative performance regulation in the 1994 periodic review of prices. We consider such a regulatory mechanism when there are technological spillovers. The regulator cannot observe firms effort and must design a regulatory contract which induces the socially optimal level of cost reduction. The extent to which cost reducing activities are non-appropriable is shown to affect the optimal choice of regulation. In general, comparative performance regulation is optimal and yardstick competition emerges only as a special case. However, when spillovers are spread evenly across an industry, an optimal comparative regime does not exist. 相似文献
35.
Szymanski B. Mazalski P. Urbaniak M. Stobiecki F. Maziewski A. Pizzini S. Maccherozzi F. 《IEEE transactions on magnetics》2010,46(2):231-234
36.
Abstract Production planning, scheduling and allocation of resources in large-scale surface mining operations present a great challenge to mine planning engineers. Ore and waste extraction plans must be executed to achieve tactical objectives using appropriate tools. Many production planning and scheduling and resource allocation methods are based on trial and error, crisis management or subjective judgements with no detailed economic basis or mathematical rigour. In addition, these methods do not consider the random processes governing critical development and production variables. In this study, the authors develop a multivariate pit shell simulator, MULSOPS, which addresses these problems. Rigorous geometric formulations of the ellipsoidal approximations of the pit shells geometry, their expansions and sequential interactions are modeled to mimic material displacement dynamics in an open pit operation. Stochastic and numerical modeling techniques are used to provide solutions to the time-dependent geometric models in random multivariate states Under different production and economic paradigms, the geometric models are simulated to yield the source and characteristics of appropriate cuts. Combined production from successive exposed cuts provides periodic targets for tactical planning. Variance simulation is also used to provide analysts with sensitive stochastic variables for input data definition and tight production target tolerance. A numerical example is used to illustrate the use of MULSOPS for tactical planning in a typical open pit operation. 相似文献
37.
Attachment of a nonaggregating monoclonal antibody and of a soluble recombinant receptor molecule to the icosahedral nonenveloped human rhinovirus serotype 2 was studied with a nanoelectrospray ionization gas-phase electrophoretic molecular mobility analyzer (nESI-GEMMA). The virus mass, as determined via nESI-GEMMA, was within instrument accuracy (+/-6%) close to the theoretical value (8 x 10(6) Da) calculated from the sum of all constituents of one virus particle (60 copies of each of the four viral capsid proteins, the RNA genome, and one copy of the RNA-linked protein VpG). The formation of virus-antibody complexes of different stoichiometries (up to a mass 12.5 x 10(6) Da corresponding to 30 attached antibodies) and virus-receptor complexes (up to a mass 8.8 x 10(6) Da corresponding to 12 attached receptor molecules) was monitored. Via the volume derived from the electrophoretic mobility diameter (EMD), the stoichiometry of the HRV complexes was calculated. The accuracy of the EMD was within +/-0.5 nm, which corresponds to an accuracy of +/-4 antibodies and +/-5 receptor molecules in the respective complexes. For the first time, we here demonstrate the use of nESI-GEMMA for the analysis of the size and stoichiometry of biomolecules in high-order complexes in real time under normal pressure conditions. 相似文献
38.
Derya Koçak Hasene Keskin Sibel Fadıloğlu Boleslaw Kowalski Fahrettin Göğüş 《Journal of the American Oil Chemists' Society》2011,88(10):1531-1538
Characterization of the fatty acid and triacylglycerol composition of terebinth fruit oil and the synthesis of structured
lipids (SL) were performed in this study. Interesterification reaction of terebinth fruits oil (Pistacia terebinthus L.) with caprylic acid (CA) and stearic acid (SA) to produce a SL was performed in n-hexane using immobilized sn-1,3 specific lipase from Mucor miehei. The effect of reaction conditions and relationship among them were analyzed by response surface methodology (RSM) with a
four-factors five-level central composite rotatable experimental design. The four major factors chosen were enzyme load (10–30 wt%
based on substrates), reaction time (7–18 h), reaction temperature (40–60 °C) and substrate mole ratio (terebinth oil:SA:CA
1:1:1–1:1:3). The best fitting quadratic model was determined by regression and backward elimination. Based on the fitted
model, the optimal reaction conditions for the incorporation of CA and SA were found to be temperature 50 °C; time 18 h; enzyme
load 30 wt%; substrate ratio 1:1:3. Under these optimum conditions, the incorporation of SA and CA could be obtained as 19
and 14%, respectively. 相似文献
39.
[Correction Notice: An erratum for this article was reported in Vol 56(2) of Journal of Counseling Psychology (see record 2009-04542-008). The DOI was incorrect. The correct DOI is 10.1037/a0013317.] Lesbian, gay, bisexual, and questioning (LGBQ) persons come from diverse cultural groups with diverse racial and ethnic identities. However, most research on LGBQ persons has used primarily White samples, and most research on African Americans has used largely heterosexual samples. Thus, research has largely failed to attend to and investigate the complexity of African American LGBQ persons' experiences. This study examined the relations between multiple internalized oppressions and African American sexual minority persons' self-esteem and psychological distress. Results indicated that when examined together, internalized racism and internalized heterosexism (also known as internalized homophobia) were both significant negative predictors of self-esteem, but only internalized heterosexism was a unique positive predictor of psychological distress. The interaction of internalized racism and internalized heterosexism was not a significant predictor of self-esteem or psychological distress. Finally, the authors' findings indicate that self-esteem partially mediates the relationship between internalized heterosexism and psychological distress. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
40.