全文获取类型
收费全文 | 693篇 |
免费 | 11篇 |
专业分类
电工技术 | 1篇 |
化学工业 | 54篇 |
建筑科学 | 48篇 |
矿业工程 | 1篇 |
能源动力 | 5篇 |
轻工业 | 45篇 |
水利工程 | 4篇 |
无线电 | 20篇 |
一般工业技术 | 185篇 |
冶金工业 | 268篇 |
原子能技术 | 3篇 |
自动化技术 | 70篇 |
出版年
2023年 | 2篇 |
2022年 | 7篇 |
2021年 | 5篇 |
2020年 | 4篇 |
2019年 | 5篇 |
2018年 | 27篇 |
2017年 | 33篇 |
2016年 | 5篇 |
2015年 | 11篇 |
2014年 | 5篇 |
2013年 | 68篇 |
2012年 | 39篇 |
2011年 | 29篇 |
2010年 | 51篇 |
2009年 | 31篇 |
2008年 | 26篇 |
2007年 | 22篇 |
2006年 | 18篇 |
2005年 | 30篇 |
2004年 | 26篇 |
2003年 | 15篇 |
2002年 | 31篇 |
2001年 | 15篇 |
2000年 | 8篇 |
1999年 | 11篇 |
1998年 | 8篇 |
1997年 | 16篇 |
1996年 | 15篇 |
1995年 | 12篇 |
1994年 | 12篇 |
1993年 | 12篇 |
1992年 | 9篇 |
1991年 | 2篇 |
1990年 | 17篇 |
1989年 | 10篇 |
1988年 | 7篇 |
1987年 | 8篇 |
1986年 | 4篇 |
1985年 | 8篇 |
1984年 | 9篇 |
1983年 | 2篇 |
1982年 | 5篇 |
1981年 | 5篇 |
1980年 | 2篇 |
1978年 | 2篇 |
1977年 | 3篇 |
1976年 | 2篇 |
1975年 | 4篇 |
1970年 | 1篇 |
1890年 | 1篇 |
排序方式: 共有704条查询结果,搜索用时 15 毫秒
71.
Chassin Laurie; Presson Clark C.; Sherman Steven J.; Edwards Debra A. 《Canadian Metallurgical Quarterly》1990,9(6):701
Assessed the magnitude of risk that adolescent cigarette smoking carries for adult smoking, using longitudinal data from 4,156 Ss surveyed originally during Grades 6–12 and followed up after completion of high school. Even infrequent experimentation (i.e., smoking only a few cigarettes) in adolescence significantly raised the risk for adult smoking by a factor of 16 compared to nonsmoking adolescents. Relative risk was also increased by early onset of smoking and by a stable, uninterrupted course from experimentation to regular smoking. Data support the importance of primary prevention programs directed at adolescent populations. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
72.
Silver Ellen J.; Bauman Laurie J.; Coupey Susan M.; Doctors Shelley R.; Boeck Marjorie A. 《Canadian Metallurgical Quarterly》1990,59(2):305
To examine the effects of chronic illness on the psychological growth process known as ego development, scores were compared on the Sentence Completion Test for 36 teens (16 boys, 20 girls) with chronic illness and 50 teens (16 boys, 34 girls) without chronic illness. Their ages ranged from 13 to 21 years, with a mean of 17.4 years. Most were Black (37%) or Hispanic (41%) and lived in poor or working-class neighborhoods. When age, sex, and Peabody Picture Vocabulary Test (PPVT) scores were controlled in multiple regression analyses, no direct association between ego development stage and presence of chronic illness, severity of illness, age at onset, or duration of illness was found. Analysis of the chronically ill group alone revealed a significant PPVT?×?Severity interaction, indicating that ego development in chronically ill teens is lower when illness is more severe and verbal IQ is higher. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
73.
Davidoff Gary; Roth Elliot; Thomas Paula; Doljanac Robert; Dijkers Marcel; Berent Stanley; Wolf Laurie; Morris Jeri; Yarkony Gary 《Canadian Metallurgical Quarterly》1990,35(3):171
Administered the Self-Rating Depression Scale (SRDS) an average of 63 days post-injury to 58 acute spinal cord injury (SCI) patients (aged 18–55 yrs) and 51 age-matched healthy controls (CTLs). Mean SRDS scores were 37.1 for CTLs and 49.0 for SCI Ss. Several factors, including age, yrs of education, level of injury (paraplegic vs quadriplegic), etiology of injury (violent vs nonviolent), presence of acute closed head injury, or recent history of alcohol or substance abuse, had no association with SRDS scores. Since undiagnosed and untreated depression may compromise an SCI patient's adaptation to injury and motivation during rehabilitation, abnormally elevated SRDS scores may help to determine which patients might require more focused psychological assessment and treatment. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
74.
Jonathan D. Urban Laurie C. Haws Mark A. Harris 《The Science of the total environment》2010,408(8):2004-2007
Buchanan et al. assert that our recent fish ingestion risk assessment for a section of the Lower Passaic River (LPR) (Urban et al., 2009) utilizes inappropriate ingestion rates and is inconsistent with state and USEPA guidelines and risk assessment procedures, and therefore underestimates the human health risks associated with angler exposure along this stretch of the river. However, they fail to support these assertions with evidence; indeed, in a recent response to similar allegations, we demonstrated that the utilized ingestion rates are, in fact, the most appropriate for this parameter (Urban et al., 2010). Our reliance on data from a comprehensive, independently validated, peer-reviewed, and site-specific creel angler survey (CAS) in order to define fish and crab ingestion rates for this region of the LPR is fully compliant with USEPA guidelines. In fact, the crab ingestion survey and risk assessment cited by Buchanan et al. as evidence of crabbing activity and crab ingestion for this region was less comprehensive than the CAS in question, was not overseen by an independent panel, has yet to be peer-reviewed, and does not provide any activity or consumption data for this section of the LPR. Contrary to the implications of Buchanan et al., our effort provides a transparent, comprehensive, and scientifically legitimate human health risk assessment of fish ingestion for the lowest 6 miles of the LPR. Thus we adamantly disagree with the characterization and assertions put forth by Buchanan et al., and stand by the conclusions presented in Urban et al. (2009) and defended in Urban et al. (2010). 相似文献
75.
Laurie Donaldson 《Materials Today》2013,16(9):306-307
77.
This study tested whether adolescent internalizing problems, externalizing problems, heavy alcohol use, fathers' parenting, and family conflict varied over time with fluctuations in fathers' alcohol impairment and also whether children of recovered alcoholic fathers differed from children of nonalcoholic fathers. Fathers and adolescent children (N?=?267 families) were interviewed in 3 annual assessments. Results showed that adolescent symptomatology and the family environment did not vary over time as a function of different trajectories of paternal alcohol impairment. However, children of recovered alcoholic fathers exhibited more symptomatology than did children of nonalcoholic fathers. Even though paternal alcoholism has remitted in these families, children of recovered alcoholic fathers might remain on a general higher risk trajectory relative to children of nonalcoholic fathers. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
78.
79.
80.