全文获取类型
收费全文 | 708篇 |
免费 | 35篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 2篇 |
综合类 | 24篇 |
化学工业 | 79篇 |
金属工艺 | 2篇 |
机械仪表 | 5篇 |
建筑科学 | 15篇 |
矿业工程 | 2篇 |
能源动力 | 6篇 |
轻工业 | 257篇 |
水利工程 | 20篇 |
无线电 | 8篇 |
一般工业技术 | 11篇 |
冶金工业 | 260篇 |
原子能技术 | 1篇 |
自动化技术 | 53篇 |
出版年
2024年 | 2篇 |
2023年 | 15篇 |
2022年 | 31篇 |
2021年 | 25篇 |
2020年 | 18篇 |
2019年 | 23篇 |
2018年 | 10篇 |
2017年 | 30篇 |
2016年 | 17篇 |
2015年 | 17篇 |
2014年 | 24篇 |
2013年 | 25篇 |
2012年 | 37篇 |
2011年 | 51篇 |
2010年 | 48篇 |
2009年 | 37篇 |
2008年 | 31篇 |
2007年 | 38篇 |
2006年 | 38篇 |
2005年 | 31篇 |
2004年 | 41篇 |
2003年 | 27篇 |
2002年 | 24篇 |
2001年 | 15篇 |
1999年 | 5篇 |
1998年 | 4篇 |
1997年 | 3篇 |
1996年 | 3篇 |
1995年 | 8篇 |
1993年 | 3篇 |
1992年 | 4篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1982年 | 5篇 |
1980年 | 1篇 |
1966年 | 4篇 |
1965年 | 1篇 |
1964年 | 7篇 |
1963年 | 3篇 |
1962年 | 3篇 |
1961年 | 4篇 |
1960年 | 6篇 |
1958年 | 2篇 |
1957年 | 2篇 |
1956年 | 1篇 |
1955年 | 6篇 |
1954年 | 4篇 |
排序方式: 共有745条查询结果,搜索用时 15 毫秒
71.
Useda J. David; Duberstein Paul R.; Conner Kenneth R.; Beckman Anthony; Franus Nathan; Tu Xin; Conwell Yeates 《Canadian Metallurgical Quarterly》2007,75(1):126
The authors tested hypotheses concerning personality differences in treatment-seeking suicide attempters (AT; n = 60) and a community sample of suicides (SU; n = 43) over age 50. On the basis of prior research, the authors hypothesized that SU would be lower in Neuroticism and Openness and higher in Conscientiousness. A 2-group (AT vs. SU) multivariate analysis of covariance with NEO Personality Inventory--Revised (Informant Version) domain scores as dependent variables revealed that SU were lower in Neuroticism and higher in Conscientiousness. The authors conclude that AT and SU in this age group can be distinguished on the basis of informant ratings of personality traits. These differences can inform risk detection. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
72.
T. Canli et al., 2004 (see record 2004-19432-002) use functional MRI to explore the neural interface between personality, mood, and emotional responses. Their finding of a double dissociation in brain response to emotional stimuli based on personality and mood state has significant implications for our understanding of the effects of personality traits and mood states on the neural bases of emotion and cognition. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
73.
A reciprocal impact hypothesis posits an influence of gender-related traits (agency and communion) on role enactment and a reciprocal impact of role enactment on gender-related traits, for both men and women. Specifically, in this study it was predicted that agency influences career success and career success influences agency. In addition, the reciprocal influence of communion and family roles was examined. A prospective study with almost 2,000 university graduates, who were tested after graduation and 1.5 years later, clearly supported the reciprocal impact hypothesis for agency and career success. Communion influenced family roles, but there was no reciprocal influence. Implications for theories of career success and of sex and gender are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
74.
Nitrophosphates and DAP are equally effective as P fertilizers for various crop species grown in rotation on a Typic Haplustept 总被引:1,自引:0,他引:1
In two long-term field experiments using wheat-maize and potato-sunflower-pearl millet (fodder) cropping systems on Typic Haplustept loamy sand, three different water-soluble P fertilizers [diammonium phosphate (DAP, water-soluble phosphorus content (WSPC) of 89.1%), ammonium nitrophosphate (ANP, WSPC 59%) and suphala (ammonium nitrophosphate, WSPC 26.7%)] were compared. Five amounts of P (0, 8.75, 17.5, 26 and 35 kg P/ha) were applied to wheat and (0, 13, 26, 39 and 52 kg P/ha) to potato. The succeeding crops under both the rotations used residual P from the P applied to wheat and potato crops. Grain yield and P content of wheat increased significantly up to an applied P level of 26 kg P/ha while the residual effect on maize crop was significant up to 17.5 kg P/ha. Tuber yield and P content of potato increased significantly up to an applied P level of 39 kg P/ha while the residual effect on sunflower and pearl millet (fodder) crops was significant up to 26 kg P/ha. Total profits in a year from wheat-maize and potato-sunflower-pearl millet (fodder) cropping systems increased significantly up to an applied P level of 26 and 39 kg P/ha, respectively. However, at all the levels of applied P and under both the cropping systems, the three P fertilizers used were found to be equally effective for plant yields, P contents, relative agronomic efficiencies and total profits in a year. Hence, it was concluded that the two nitrophosphates can be used instead of DAP as P fertilizers for the soil, plant species and crop rotations studied. 相似文献
75.
Comments on the original article "Patterns of Mean-Level Change in Personality Traits Across the Life Course: A Meta-Analysis of Longitudinal Studies," by B. W. Roberts, K. W. Walton, and W. Viechtbauer (see record 2006-00818-001). Although Roberts et al depicted the present authors as proponents of the immutability of traits, in fact we have always acknowledged the possibility of change, and we are pleased that the results of their meta-analysis are consistent with our conclusions about modest change after age 30. We agree with B.W. Roberts et al that analyses should be conducted at the level of more specific traits, but prefer the 30 facets of the Revised NEO Personality Inventory to the Social Dominance-Social Vitality distinction. The origins of age changes might be found either in environmental influences common to all cultures or in biologically based intrinsic maturation; we offer some reasons for preferring the latter interpretation. Meta-analyses are useful but not definitive, and the resolution of the origin question lies in further research. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
76.
为更深入地揭示情绪特质对建筑工人危险感知行为的影响规律,减少事故发生,立足中国建筑工人的群体与个体特质,以情绪等相关理论为支撑,基于自主开发的“情绪特质-危险感知”问卷,利用科学统计方法与指标,探究了不同情绪特质下工人的危险感知行为差异。结果表明:工人的危险感知能力与情绪特质呈正相关,良好的情绪管理能力有利于增强工人危险感知能力;情绪特质最直接影响工人危险知觉水平,情绪化的工人危险知觉水平偏弱;工人良好的情绪管理能力对危险认知有显著影响,最显著体现为提高工人信息分析稳定性。 相似文献
77.
Due to their nutrient recycling function and their importance in food-webs, macroinvertebrates are essential for the functioning of aquatic ecosystems. These organisms also constitute an important component of biodiversity.Sediment evaluation and monitoring is an essential aspect of ecosystem monitoring since sediments represent an important component of aquatic habitats and are also a potential source of contamination. In this study, we focused on macroinvertebrate communities within run-of-river dams, that are prime areas for sediment and pollutant accumulation. Little is known about littoral macroinvertebrate communities within run-of-river dam or their response to sediment levels and pollution. We therefore aimed to evaluate the following aspects: the functional and structural composition of macroinvertebrate communities in run-of-river dams; the impact of pollutant accumulation on such communities, and the most efficient scales and tools needed for the biomonitoring of contaminated sediments in such environments. Two run-of-river dams located in the French alpine area were selected and three spatial scales were examined: transversal (banks and channel), transversal × longitudinal (banks/channel × tail/middle/dam) and patch scale (erosion, sedimentation and vegetation habitats). At the patch scale, we noted that the heterogeneity of littoral habitats provided many available niches that allow for the development of diversified macroinvertebrate communities. This implies highly variable responses to contamination. Once combined on a global ‘banks’ spatial scale, littoral habitats can highlight the effects of toxic disturbances. 相似文献
78.
79.
The difficulties of operationalizing race in research and practice for social, behavioral, and genetic researchers and practitioners are neither new nor related to recent genetic knowledge. For geneticists, the bases for understanding groups are clines, observed traits that gradually change in frequency between geographic regions without distinct identifiable population boundaries and population histories that carry information about the distribution of genetic variants. For psychologists, race may not exist or be a social and cultural construct associated with fluid social inferences. Because definitions of populations and race can be socially and biologically incongruent, the authors suggest that geneticists and social and behavioral scientists and clinicians attend to external validity issues by operationalizing population and racial categories and avoiding race proxies for other biological, social, and cultural constructs in research designs, data analyses, and clinical practice. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
80.
A collaborative study among three nations (France, Belgium, Netherlands) along the Meuse River developed a consistent approach for collecting and interpreting macroinvertebrate data. Specific mesohabitats were sampled in 16 locations along an 800‐km stretch of this lowland regulated river. The objective was to assess the ‘river health’ using macroinvertebrate communities as indicators of biological and ecological variation in space. The main changes in assemblages were investigated using multimetric and multivariate approaches. The authors examined relationships between faunal variations and both physico‐chemical gradients and man‐made disturbances. We related species traits to faunal changes and habitat characteristics. Both a gradual shift from a macroinvertebrate assemblage dominated by insects to a community dominated by crustaceans and molluscs and a drastic decrease in biotic index values were observed along the longitudinal gradient. Taxa were distributed according to oxygen, nitrate and ammonium concentrations, pH, conductivity and summer hydraulic conditions. But major faunal differences among sites could not be explained simply by physico‐chemical variables. The trait analysis underlined the role of temporary habitats in structuring the summer macroinvertebrate community of sites of the uppermost French sector, which supported the most diverse community in terms of trait combination. Downstream the macroinvertebrate community exhibited a more simple and less stable functional organization. We concluded that the Meuse River exhibited both a high biodiversity and a ‘reasonably good’ water quality in the upper reaches. Two transition zones highlighted the influence of a high degree of human impact on stream integrity. Regulation for navigation, ship traffic and heavily polluted effluent discharges influenced instream conditions via multiple processes determining a decline of both habitat stability and diversity. However, the rare occurrence of habitat‐sensitive species in the lower reaches indicated that a partial recovery of communities may be predicted if restoration and protection of disturbed (especially riparian) habitats are fulfilled. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献