全文获取类型
收费全文 | 2868篇 |
免费 | 114篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 12篇 |
综合类 | 1篇 |
化学工业 | 572篇 |
金属工艺 | 19篇 |
机械仪表 | 36篇 |
建筑科学 | 150篇 |
矿业工程 | 5篇 |
能源动力 | 60篇 |
轻工业 | 337篇 |
水利工程 | 23篇 |
石油天然气 | 5篇 |
无线电 | 139篇 |
一般工业技术 | 403篇 |
冶金工业 | 923篇 |
原子能技术 | 3篇 |
自动化技术 | 296篇 |
出版年
2023年 | 19篇 |
2022年 | 68篇 |
2021年 | 78篇 |
2020年 | 41篇 |
2019年 | 46篇 |
2018年 | 67篇 |
2017年 | 65篇 |
2016年 | 49篇 |
2015年 | 60篇 |
2014年 | 66篇 |
2013年 | 147篇 |
2012年 | 130篇 |
2011年 | 175篇 |
2010年 | 124篇 |
2009年 | 147篇 |
2008年 | 134篇 |
2007年 | 134篇 |
2006年 | 127篇 |
2005年 | 116篇 |
2004年 | 98篇 |
2003年 | 82篇 |
2002年 | 104篇 |
2001年 | 50篇 |
2000年 | 61篇 |
1999年 | 65篇 |
1998年 | 49篇 |
1997年 | 45篇 |
1996年 | 62篇 |
1995年 | 50篇 |
1994年 | 51篇 |
1993年 | 45篇 |
1992年 | 44篇 |
1991年 | 12篇 |
1990年 | 31篇 |
1989年 | 38篇 |
1988年 | 30篇 |
1987年 | 31篇 |
1986年 | 28篇 |
1985年 | 24篇 |
1984年 | 29篇 |
1983年 | 24篇 |
1982年 | 26篇 |
1981年 | 19篇 |
1980年 | 15篇 |
1979年 | 12篇 |
1978年 | 8篇 |
1977年 | 7篇 |
1976年 | 8篇 |
1975年 | 9篇 |
1974年 | 8篇 |
排序方式: 共有2984条查询结果,搜索用时 15 毫秒
11.
High-performance liquid chromatography of human milk triacylglycerols and gas chromatography of component fatty acids 总被引:1,自引:0,他引:1
Human milk triacylglycerols were separated by high-performance liquid chromatography. A 5-μ Supelcosil LC-18 column (Supelco,
Inc., Bellefonte, PA) was used with acetone/acetonitrile (64∶36, vol/vol) as mobile phase. Triacylglycerols were tentatively
identified based on theoretical carbon number and relative retention time. Despite changes resulting from dietary fat variation,
the major component triacylglycerols were those composed of palmitic, oleic and linoleic acids. Triacylglycerols with palmitic,
stearic and oleic acids were present as minor components. Fatty acids were quantified by gas chromatography relative to an
internal standard. Ratios of n−6/n−3 fatty acids were found to be high than previously reported.
Based on a paper presented at the Symposium on Milk Lipids held at the AOCS Annual Meeting, Baltimore, MD, April 1990. 相似文献
12.
Allen Daniel N.; Strauss Gregory P.; Kemtes Karen A.; Goldstein Gerald 《Canadian Metallurgical Quarterly》2007,21(6):713
Hemispheric involvement in reasoning abilities has been debated for some time, and it remains unclear whether the right hemisphere's involvement in problem solving is modality specific or dependent on the type of spatial reasoning required. In the current study, 2 types of nonverbal reasoning abilities were examined, spatial reasoning and proportional reasoning, in 109 patients with cerebrovascular disease that was confined to either the right or the left hemisphere or was diffuse in nature. Results indicated that no lateralizing effects were present based on type of spatial reasoning. Findings are consistent with the suggestion that higher order cognitive processes involved in nonverbal abstraction and problem solving are not strongly lateralized to the right hemisphere but rather are more generally distributed throughout the cortex. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
13.
14.
Examined the extent to which isolated and aggressive 6th graders compensate for unsatisfying school friendships by deriving support from siblings and nonschool friends and whether this support protects such children from poor socioemotional outcomes. Results were as follows: (1) When compared with average and aggressive children, isolated children perceived their school friendships as least supportive and their favorite sibling relationships as most supportive; (2) isolated, aggressive, and average children did not differ in their perceptions of support from nonschool friends; and (3) high support from a favorite sibling was associated with better adjustment among isolated children on select outcomes. Despite the somewhat ameliorating role of siblings for isolated children, isolated children with high sibling support remained less well adjusted than did average children. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
15.
16.
Atkinson-Leadbeater Karen; Nuttley William M.; van der Kooy Derek 《Canadian Metallurgical Quarterly》2004,118(6):1206
A learning event can be dissociated into 3 components: acquisition, storage, and recall. When the laboratory wild-type strain of Caenorhabditis elegans (N2 strain) is exposed to benzaldehyde in the absence of food, the worms display a reduction of their attractive response to this volatile odorant. This results from the association between benzaldehyde and a nutrient-deficient environment. Another wild-type isolate, the CB4856 strain, fails to display this decreased response to benzaldehyde after exposure to benzaldehyde in the absence of food. However, like the N2 strain, when tested to isoamyl alcohol after benzaldehyde conditioning, the CB4856 strain displays a decreased isoamyl alcohol response. Therefore, the CB4856 strain does not have an acquisition deficit, but it suffers from a recall deficit specific to benzaldehyde. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
17.
Examined the relation between gender and reactions to different styles of advertising tobacco and alcohol products among 41 females and 34 males (aged 12–16 yrs) and their parents (39 mothers and 36 fathers). Self-monitoring was also examined as a possible correlate. Ss rated magazine advertisements oriented toward the product's image or qualities. Girls liked image-oriented advertisements more and perceived them to be more persuasive than quality-oriented advertising. This gender difference was not observed among adults. All Ss liked image-oriented more than quality-oriented advertising. Moreover, image-oriented advertisements were seen as more persuasive than quality-oriented advertisements by girls' parents who were high in self-monitoring. Results suggest that girls in early adolescence may be particularly attentive to image-oriented commercials that portray smoking and drinking as desirable behaviors. (French abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
18.
Thompson Robert J.; Gil Karen M.; Keith Barbara R.; Gustafson Kathryn E.; George Linda K.; Kinney Thomas R. 《Canadian Metallurgical Quarterly》1994,62(4):856
Rates of poor psychological adjustment of children with sickle cell disease remained relatively constant over initial and follow-up assessment points. 50 children (aged 7–12 yrs) and their mothers completed the initial protocol. 30 children completed the follow-up plus 5 additional children and their mothers. These Ss were aged 7–24 yrs at follow-up. With initial levels of adjustment controlled, children's strategies for coping with pain accounted for a significant increment in child-reported symptoms and mother-reported internalizing behavior problems at follow-up beyond the contribution of illness and demographic parameters and follow-up interval. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
19.
Allen Karen; Linn Richard T.; Gutierrez Horacio; Willer Barry S. 《Canadian Metallurgical Quarterly》1994,39(1):29
Investigated burden experienced by 60 spouses and 71 parents who served as primary caregivers to individuals with traumatic brain injury (BI). Burden levels, as assessed by the Questionnaire on Resources and Stress (QRS-SF), were compared for spouses and parents. Both parents and spouses exhibited high levels of burden. Relative to spouses, parents reported significantly greater burden related to lifespan care. Spouses reported significantly less personal reward than did parents. The presence of social aggression and cognitive disability in the individual with BI was found to have a greater association with subjective burden of caregivers than was the presence of physical disability or injury severity. Results of previous studies with QRS-SF scores show that the responsibility assumed by spouses and parents of persons with BI was as great as that experienced by families of people with severe chronic physical disabilities. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
20.
H. H. Kendler (see record 1994-09190-001), in his article on psychology and the ethics of social policy, argues in part that ethical imperatives cannot be inferred from empirical data. This argument is cited in opposition to what is purported to be the position of the American Psychological Association on the abortion issue. It is suggested that PhD candidates in psychology be well versed in the philosophical issues and debates that are the foundation for the formation of ethical principles. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献