全文获取类型
收费全文 | 924篇 |
免费 | 36篇 |
专业分类
电工技术 | 3篇 |
化学工业 | 274篇 |
金属工艺 | 6篇 |
机械仪表 | 10篇 |
建筑科学 | 71篇 |
矿业工程 | 2篇 |
能源动力 | 20篇 |
轻工业 | 164篇 |
水利工程 | 1篇 |
石油天然气 | 2篇 |
无线电 | 33篇 |
一般工业技术 | 86篇 |
冶金工业 | 206篇 |
原子能技术 | 1篇 |
自动化技术 | 81篇 |
出版年
2023年 | 11篇 |
2022年 | 19篇 |
2021年 | 28篇 |
2020年 | 13篇 |
2019年 | 18篇 |
2018年 | 25篇 |
2017年 | 21篇 |
2016年 | 24篇 |
2015年 | 20篇 |
2014年 | 25篇 |
2013年 | 54篇 |
2012年 | 45篇 |
2011年 | 41篇 |
2010年 | 43篇 |
2009年 | 36篇 |
2008年 | 43篇 |
2007年 | 44篇 |
2006年 | 43篇 |
2005年 | 33篇 |
2004年 | 37篇 |
2003年 | 20篇 |
2002年 | 21篇 |
2001年 | 14篇 |
2000年 | 14篇 |
1999年 | 14篇 |
1998年 | 9篇 |
1997年 | 7篇 |
1996年 | 9篇 |
1995年 | 10篇 |
1994年 | 6篇 |
1993年 | 17篇 |
1992年 | 6篇 |
1991年 | 5篇 |
1990年 | 10篇 |
1989年 | 8篇 |
1988年 | 11篇 |
1987年 | 5篇 |
1986年 | 5篇 |
1985年 | 5篇 |
1984年 | 8篇 |
1979年 | 5篇 |
1977年 | 5篇 |
1974年 | 5篇 |
1966年 | 12篇 |
1965年 | 13篇 |
1964年 | 9篇 |
1963年 | 13篇 |
1962年 | 9篇 |
1961年 | 12篇 |
1960年 | 11篇 |
排序方式: 共有960条查询结果,搜索用时 9 毫秒
81.
Phillips Louise H.; Bull Rebecca; Adams Ewan; Fraser Lisa 《Canadian Metallurgical Quarterly》2002,2(1):12
Contrasting predictions have been made about the effects of positive mood states on the performance of frontal lobe tests that tap executive functions such as inhibition, switching, and strategy use. It has been argued that positive mood is likely to improve some cognitive processes, particularly those dependent on the frontal cortex and anterior cingulate of the brain. However, there is some evidence that happy mood may impair executive functioning. The current experiments investigated the effects of positive mood on Stroop and fluency tests, which are frequently used to assess executive function. Positive mood impaired performance on a switching condition of the Stroop test, but improved performance on a creative uses test of fluency. The effect of positive mood on an executive task may therefore depend on whether a task is inherently motivating or is impaired by diffuse semantic activation. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
82.
83.
Conducted an occupational analysis of counseling psychology to determine the work that counseling psychologists do, their feelings toward their work, and their perceptions of how the field is changing. Questionnaire responses of 351 counseling psychologists (aged 28–86 yrs) were evaluated and compared in terms of demographic and work behavior information. Results indicate that Ss were, in general, strongly practice oriented and appeared to see themselves as engaged in psychotherapy and traditionally clinical activities with a reduced emphasis on academic and research-focused behaviors. This finding was particularly true of the younger respondents. Results are discussed in terms of their implications for the counseling–clinical distinction and the scientist–practitioner model. It is concluded that counseling psychology appears to be an increasingly applied specialty and that vocational/career counseling appears to be eroding as the foundation of the discipline. (21 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
84.
Garden Sharin E.; Phillips Louise H.; MacPherson Sarah E. 《Canadian Metallurgical Quarterly》2001,15(4):472
The frontal lobes show early signs of structural and functional change in the course of adult aging. The 1st study of the current article examined whether midlife aging influences open-ended planning, a skill that is particularly sensitive to frontal lobe damage. There were no midlife declines in the ability to carry out variants of the T. Shallice and P. Burgess (1991) Six Elements and Multiple Errands Tests. Younger adults were more likely to break individual task rules. In a 2nd experiment, middle-aged adults performed worse than young adults did on laboratory executive tests sensitive to frontal lobe damage—Self-Ordered Pointing and the Wisconsin Card Sorting Test (N. M. Fristoe, T. A. Salthouse, & J. L. Woodard, 1997). In spite of changes in novel executive test performance, real-world executive skills appear to be spared in midlife aging. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
85.
Synthesis,characterization, photocatalytic evaluation,and toxicity studies of TiO2–Fe3+ nanocatalyst
Iliana Medina-Ramírez Jingbo Louise Liu Araceli Hernández-Ramírez Cristina Romo-Bernal Gladis Pedroza-Herrera Juan Jáuregui-Rincón Miguel A. Gracia-Pinilla 《Journal of Materials Science》2014,49(15):5309-5323
Based on our previous work on the green preparation of Ag–TiO2 photocatalyst with bactericidal activity under visible light, we extended our studies to the synthesis of TiO2–Fe3+ materials with enhanced photocatalytic activity for the degradation of recalcitrant organic pollutants in water. TiO2–Fe3+ nanopowders were synthesized using a robust, environmentally friendly procedure. Established amounts of Fe(NO3)3·9H2O and titanium tetraisopropoxide (TTIP) were mixed using glacial acetic acid as solvent. Hydrolysis of TTIP–Fe3+ was accomplished using a 30 % (W/V) Arabic gum aqueous solution. TiO2–Fe3+ nanopowders were obtained by thermal treatment at 400 °C. In order to elucidate the structure of these photocatalysts, microscopic and spectroscopic characterization techniques were applied. The high resolution transmission electron microscopy (HRTEM) analysis indicated the presence of uniformly distributed particles with average particle size of about 9 nm. According to the HRTEM lattice fringes, ring pattern, and selected area electron diffraction pattern, the crystalline part of the samples consists of anatase (PDF 01-086-1157 with the lattice constant of 3.7852, 9.5139 Å and 90°) as dominant phase. X-ray photoelectron spectroscopy (XPS) was applied to determine the oxidation state of iron. The XPS provides evidence for Fe3+ surface species in the TiO2–Fe3+ composite. Complete degradation of aqueous solutions (20 ppm) of methylene blue and/or methyl orange was accomplished after 4 h of treatment using 150 mg of TiO2–Fe3+/150 mL of dye solution. The in vitro toxicity of the materials was tested. The materials showed no toxicity against human red blood cells. 相似文献
86.
Joaquín Prada Jiménez de Cisneros Michael J. Stear Colette Mair Darran Singleton Thorsten Stefan Abigail Stear Glenn Marion Louise Matthews 《Journal of the Royal Society Interface》2014,11(99)
Gastrointestinal nematodes are a global cause of disease and death in humans, wildlife and livestock. Livestock infection has historically been controlled with anthelmintic drugs, but the development of resistance means that alternative controls are needed. The most promising alternatives are vaccination, nutritional supplementation and selective breeding, all of which act by enhancing the immune response. Currently, control planning is hampered by reliance on the faecal egg count (FEC), which suffers from low accuracy and a nonlinear and indirect relationship with infection intensity and host immune responses. We address this gap by using extensive parasitological, immunological and genetic data on the sheep–Teladorsagia circumcincta interaction to create an immunologically explicit model of infection dynamics in a sheep flock that links host genetic variation with variation in the two key immune responses to predict the observed parasitological measures. Using our model, we show that the immune responses are highly heritable and by comparing selective breeding based on low FECs versus high plasma IgA responses, we show that the immune markers are a much improved measure of host resistance. In summary, we have created a model of host–parasite infections that explicitly captures the development of the adaptive immune response and show that by integrating genetic, immunological and parasitological understanding we can identify new immune-based markers for diagnosis and control. 相似文献
87.
Environmental tax reform (ETR) is widely accepted to be a policy with desirable environmental, and other economic effects. The question arises then as to why its implementation has been so patchy. There is a broad literature on the economic impact of ETR, however, there have been very few research efforts devoted to understanding the roles and imperatives of the public, policy makers, businesses and other stakeholders who are addressed by ETR. This paper examines the impediments to ETR in Ireland. Focus groups were formed comprising of members of the general public and these provided a forum for detailed reactions to the ETR concept. Interviews were conducted with policy makers and key business people in an attempt to identify both the patterns of thinking behind ETR and the main obstacles to its introduction. Having presented the results, a theory of the main impediments to ETR is developed. The opinions of the members of the public, the business community and the policy makers highlight a number of issues that need to be addressed in the future design of ETR in Ireland. The principal potential impediments to ETR include: mistrust of the government, implausibility of the policy, means of hypothecation, information asymmetries, the political system, the structure of government, the macroeconomic environment, the impact on competitiveness, inequity between sectors, regressivity, elasticities and the level of the tax, terminology, and the marketing of ETR. 相似文献
88.
Louise Pasternack 《Combustion and Flame》1992,90(3-4):259-268
Boron has practical applications as an advanced fuel in propulsion systems due to its high energy content. The combustion of boron in the presence of hydrocarbon fuels is a complex problem involving heterogeneous particle oxidation followed by gas-phase kinetics of the volatilized boron species. In this study, we have modeled the high-temperature gas-phase combustion chemistry of the B/O/H/C system. We have examined the effects of recent experimental gas-phase kinetic measurements of several of the critical reaction rates and theoretical thermodynamic and transition state calculations on the previous model of boron combustion. Additional reactions that critically affect the combustion efficiency are identified for future experimental and theoretical study. The role of boron oxyhydrides, which are metastable species, is discussed. 相似文献
89.
Bowden L Faulkner R Clancy C Gallagher A Devine M Gorman D O'Reilly G Dowling A 《Radiation protection dosimetry》2011,147(1-2):210-214
Current guidelines quote tolerances for automatic exposure control (AEC) device performance for X-ray systems as 'Baseline ± X %'. However, in the situation where a baseline figure has not yet been achieved, as in the case of commissioning assessments, this tolerance is not relevant. The purpose of this work is to provide mean doses for direct digital radiography (DDR) X-ray system, operating in AEC, against which comparisons can be made. Dose measurements have been recorded under AEC operation on 29 DDR detectors from three different manufacturers. Two different testing protocols were examined: (1) water equivalent phantoms in front of the DDR detector and (2) aluminium block at the tube head. The average patient exit dose, using the aluminium block was 4.6 μGy with the antiscatter grid in place and 4.0 μGy with the grid removed. Using the water phantoms, the average dose was measured at 17.1 μGy with the antiscatter grid in place and 5.4 μGy with grid removed. Based on these results, it is clear that different testing configurations significantly impact on the measured dose. 相似文献
90.
Bennett LE Singh DP Clingeleffer PR 《Critical reviews in food science and nutrition》2011,51(1):38-49
A selection of Australian and imported fresh and dried fruit products, including sultanas, Sunmuscats, Carina currants, Zante currants, apricots, and prunes, were analyzed for selected minerals (Ca, Mg, Na, S, B, Al, Fe, Mn, Cu, Zn, Mo, and Se), folate and vitamin C, and the capacity of dried fruits for dietary provision of these micronutrients evaluated. Micro-nutrients were concentrated by a factor of 3-5 in dried fruits compared with their fresh fruit counterparts and were consequently present in nutritionally significant levels, in contrast to fresh fruit. Australian dried sultanas, Carina currant, Zante currant, apricots, and prunes contained Cu, Fe, K, and Mn at levels of >20% of daily Required Dietary Intake (RDI, taken as the average for adult men and women as nominated by the Australian National Health and Medical Research Council) and Sunmuscats contained Cu, Fe, and K at >20% of RDI. All dried fruits studied contained boron in the range of 1.5 to 5.4 mg per 100 g; however, the RDI for boron has not been defined by the NHMRC at the present time. All sultanas and currants studied contained folate at levels of 10-20% of RDI per 100 g. Experimental drying methods significantly affected folate levels with higher folate content in non-ground versus ground-based drying methods. Of the micro-nutrients supplying >20% of RDI, folate represents a particular nutrient for which the mean daily intake of adult Australians is typically inadequate. This study shows that dried fruit consumption, in contrast with fresh fruit, can provide significant proportions of daily requirements of several micronutrients, particularly folate. 相似文献