全文获取类型
收费全文 | 3595篇 |
免费 | 146篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 20篇 |
综合类 | 1篇 |
化学工业 | 731篇 |
金属工艺 | 27篇 |
机械仪表 | 49篇 |
建筑科学 | 184篇 |
矿业工程 | 7篇 |
能源动力 | 71篇 |
轻工业 | 418篇 |
水利工程 | 27篇 |
石油天然气 | 6篇 |
无线电 | 189篇 |
一般工业技术 | 536篇 |
冶金工业 | 1085篇 |
原子能技术 | 11篇 |
自动化技术 | 383篇 |
出版年
2023年 | 23篇 |
2022年 | 63篇 |
2021年 | 90篇 |
2020年 | 44篇 |
2019年 | 51篇 |
2018年 | 76篇 |
2017年 | 74篇 |
2016年 | 62篇 |
2015年 | 72篇 |
2014年 | 86篇 |
2013年 | 195篇 |
2012年 | 151篇 |
2011年 | 205篇 |
2010年 | 150篇 |
2009年 | 176篇 |
2008年 | 165篇 |
2007年 | 171篇 |
2006年 | 151篇 |
2005年 | 143篇 |
2004年 | 115篇 |
2003年 | 93篇 |
2002年 | 122篇 |
2001年 | 65篇 |
2000年 | 72篇 |
1999年 | 81篇 |
1998年 | 93篇 |
1997年 | 79篇 |
1996年 | 83篇 |
1995年 | 63篇 |
1994年 | 62篇 |
1993年 | 57篇 |
1992年 | 61篇 |
1991年 | 23篇 |
1990年 | 38篇 |
1989年 | 43篇 |
1988年 | 35篇 |
1987年 | 36篇 |
1986年 | 36篇 |
1985年 | 33篇 |
1984年 | 35篇 |
1983年 | 27篇 |
1982年 | 35篇 |
1981年 | 23篇 |
1980年 | 16篇 |
1979年 | 16篇 |
1978年 | 16篇 |
1977年 | 24篇 |
1976年 | 29篇 |
1975年 | 17篇 |
1974年 | 12篇 |
排序方式: 共有3745条查询结果,搜索用时 125 毫秒
21.
R Albrecht TC Awes C Baktash P Beckmann F Berger R Bock G Claesson G Clewing L Dragon A Eklund RL Ferguson A Franz S Garpman R Glasow HA Gustafsson HH Gutbrod J Idh P Jacobs K Kampert BW Kolb P Kristiansson IY Lee H Loehner I Lund FE Obenshain A Oskarsson I Otterlund T Peitzmann S Persson F Plasil AM Poskanzer M Purschke H Ritter S Saini R Santo HR Schmidt T Siemiarczuk SP Sorensen E Stenlund ML Tincknell GR Young 《Canadian Metallurgical Quarterly》1991,44(6):2736-2752
22.
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
23.
Thompson Robert J.; Gil Karen M.; Burbach Daniel J.; Keith Barbara R.; Kinney Thomas R. 《Canadian Metallurgical Quarterly》1993,61(3):468
In this study, 64% of children aged 7–12 yrs with sickle cell disease were found to have a parent-reported behavior problem, and 50% met the criteria for a Diagnostic and Statistical Manual of Mental Disorders-III-Revised (DSM-III-R) diagnosis based on a structured clinical interview of the child. Internalizing types of behavior problems and diagnoses were the most frequent. Support was provided for a transactional stress and coping model in delineating the processes associated with child adjustment. In particular, maternal anxiety accounted for 16–33% of the variance in mother-reported internalizing and externalizing behavior problems, respectively, and child pain-coping strategies accounted for 21% of the variance in child-reported adjustment problems. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
24.
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
25.
26.
Schlak M. Weinert C.M. Albrecht P. Nolting H.-P. 《Photonics Technology Letters, IEEE》1991,3(1):15-16
The use of a two-dimensional finite difference simulation technique to determine optimal design parameters for the fabrication of TE/TM-mode converters on (001) InP substrate is discussed. Based on design rules extracted from the calculations, a tunable device for an operating wavelength of 1.56 μm has been fabricated and polarization conversion of 45°, suitable for operation in a polarization diversity network has been achieved at an effective voltage of 32 V 相似文献
27.
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
28.
KarenParnell 《世界电子元器件》2002,(3):39-40
在英国现在每3分钟就有一部移动电话被盗。这一现象并不仅局限于英国,而是一个全球问题,并且数量在不断上升。例如,在澳大利亚的新南威尔士,1999年10月至2000年9月间约有4万部移动电话被偷或被抢,比前一年增长了100%。 相似文献
29.
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
30.
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