全文获取类型
收费全文 | 3810篇 |
免费 | 137篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 30篇 |
化学工业 | 843篇 |
金属工艺 | 30篇 |
机械仪表 | 68篇 |
建筑科学 | 136篇 |
矿业工程 | 10篇 |
能源动力 | 65篇 |
轻工业 | 683篇 |
水利工程 | 43篇 |
石油天然气 | 9篇 |
无线电 | 162篇 |
一般工业技术 | 371篇 |
冶金工业 | 1145篇 |
原子能技术 | 8篇 |
自动化技术 | 345篇 |
出版年
2023年 | 22篇 |
2022年 | 92篇 |
2021年 | 88篇 |
2020年 | 66篇 |
2019年 | 53篇 |
2018年 | 70篇 |
2017年 | 72篇 |
2016年 | 70篇 |
2015年 | 70篇 |
2014年 | 94篇 |
2013年 | 232篇 |
2012年 | 164篇 |
2011年 | 192篇 |
2010年 | 144篇 |
2009年 | 165篇 |
2008年 | 146篇 |
2007年 | 163篇 |
2006年 | 129篇 |
2005年 | 134篇 |
2004年 | 119篇 |
2003年 | 115篇 |
2002年 | 98篇 |
2001年 | 70篇 |
2000年 | 75篇 |
1999年 | 75篇 |
1998年 | 112篇 |
1997年 | 84篇 |
1996年 | 66篇 |
1995年 | 58篇 |
1994年 | 60篇 |
1993年 | 50篇 |
1992年 | 57篇 |
1991年 | 23篇 |
1990年 | 48篇 |
1989年 | 58篇 |
1988年 | 43篇 |
1987年 | 57篇 |
1986年 | 48篇 |
1985年 | 48篇 |
1984年 | 34篇 |
1983年 | 27篇 |
1982年 | 46篇 |
1981年 | 30篇 |
1980年 | 28篇 |
1978年 | 31篇 |
1977年 | 24篇 |
1976年 | 18篇 |
1975年 | 21篇 |
1974年 | 18篇 |
1973年 | 18篇 |
排序方式: 共有3948条查询结果,搜索用时 15 毫秒
11.
Butler Emily A.; Egloff Boris; Wlhelm Frank H.; Smith Nancy C.; Erickson Elizabeth A.; Gross James J. 《Canadian Metallurgical Quarterly》2003,3(1):48
At times, people keep their emotions from showing during social interactions. The authors' analysis suggests that such expressive suppression should disrupt communication and increase stress levels. To test this hypothesis, the authors conducted 2 studies in which unacquainted pairs of women discussed an upsetting topic. In Study 1, one member of each pair was randomly assigned to (a) suppress her emotional behavior, (b) respond naturally, or (c) cognitively reappraise in a way that reduced emotional responding. Suppression alone disrupted communication and magnified blood pressure responses in the suppressors' partners. In Study 2, suppression had a negative impact on the regulators' emotional experience and increased blood pressure in both regulators and their partners. Suppression also reduced rapport and inhibited relationship formation. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
12.
Paraquat (1,1'-dimethyl-4,4'-dipyridylium) is an herbicide associated with both accidental and intentional ingestion, leading to severe and often fatal toxicity. Prognosis is largely dependent on the amount of paraquat absorbed. Rapid identification of the symptoms of paraquat toxicity (burns or ulceration at the site of ingestion or injection, acute respiratory distress, and renal failure) can facilitate early treatment intervention to limit absorption. We report a case of a 71-year-old man with a suicidal ingestion of paraquat 2 days prior to presentation. Serum paraquat levels, time elapsed since ingestion, and clinical symptoms all indicated poor prognosis. The patient developed severe respiratory distress and progressive renal failure, and died 6 days after admission to the hospital. 相似文献
13.
One requirement in designing and operating and operating system is to minimize the moisture change in stored grain. Moisture transfer during the aeration process is generally believed to be caused by the partial pressure difference between water in grain and water in air (P3-P4). A mathematical model was developed for rough rice, which predicts the partial pressure difference under various grain and ambient conditions. Observations of moisture change over 10 aeration tests confirmed the good correlation between sorption phenomena and partial pressure differences. Studies indicated that air relative humidity, air temperature, grain temperature and grain moisture are significant factors influencing the partial pressure differences and, thus, affecting 相似文献
14.
A motivational model of rural students' intentions to persist in, versus drop out of, high school. 总被引:1,自引:0,他引:1
Using self-determination theory, the authors tested a motivational model to explain the conditions under which rural students formulate their intentions to persist in, versus drop out of, high school. The model argues that motivational variables underlie students' intentions to drop out and that students' motivation can be either supported in the classroom by autonomy-supportive teachers or frustrated by controlling teachers. LISREL analyses of questionnaire data from 483 rural high school students showed that the provision of autonomy support within classrooms predicted students' self-determined motivation and perceived competence. These motivational resources, in turn, predicted students' intentions to persist, versus drop out, and they did so even after controlling for the effect of achievement. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
15.
Experiments were conducted to investigate the fate of ethylbenzoate and soil microorganisms in shallow aquifers. Biodegradation and volatilization have been identified as the major mechanisms in attenuating ethylbenzoate in contaminated soils. The rate of volatilization was experimentally found to be limited by gas-phase diffusion. The parameters of an available model, i.e., the maximum specific growth rate and the saturation constant, have been estimated by fitting the model to the experimental data obtained with ethylbenzoate as the carbon source; the former was 0.49 h−1, and the latter was 62 mg L−1. Various facets of biodegradation, including the effects of mass-transfer resistance and initial distribution of microorganisms, have been numerically analyzed on the basis of the model. 相似文献
16.
McEvoy Cathy L.; Nelson Douglas L.; Holley Patricia E.; Stelnicki Glennda S. 《Canadian Metallurgical Quarterly》1992,7(3):401
Reports 2 cued recall experiments in which younger and older Ss studied target words varying in number of preexperimental associates. In Exp 1, targets were studied in either the absence or presence of meaning-related context cues, with recall always prompted by the cues. In the absence of context, words with smaller sets of associates were easier to recall than those with larger sets, but this effect was reduced for older Ss. The presence of a study context cue facilitated recall and eliminated the effect of associative set size for both ages. In Exp 2, targets were studied and tested in the presence of unrelated words. In this situation, words with smaller sets of associates were less likely to be recalled than words with larger sets; again the effect was reduced for older Ss. The results are interpreted as an age decrement in processing implicitly activated information. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
17.
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
18.
19.
Investigated the extent to which attention can be voluntarily allocated across the visual field during a single fixation. In Exp I, 20 undergraduates made a reaction time (RT) response to a stimulus occurring in a cued or a noncued location while maintaining a center fixation. In Exp II, 3 naive and 5 experienced undergraduates underwent a replication of Exp I and were monitored for horizontal eye movement during head restraint. Results from Exp I indicate that Ss were constrained to voluntarily attending to a single primary focus in space, and these findings were supported in Exp II. Data replicate those found by M. I. Posner et al (see record 1981-11809-001). (French abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
20.
Blotcky Alan D.; Cohen Debra G.; Conatser Cheryl; Klopovich Patricia 《Canadian Metallurgical Quarterly》1985,53(5):729
Examined psychosocial variables by comparing 10 13–17 yr old adolescents (and their mothers) who had refused cancer treatment with a group of 10 consenting adolescents who were matched on age and demographic and illness variables. Adolescents completed the State-Trait Anxiety Inventory for Children and measures of family characteristics, locus of control, religion, hopelessness, impact of event, and satisfaction with physician. Mothers completed the State-Trait Anxiety Inventory and measures of coping and religion. Adolescent refusers scored lower on state anxiety and subjective distress but scored higher on trait anxiety, religiosity, and external locus of control. Their mothers also scored higher than did the consenting-group mothers on religiosity and trait anxiety. It is suggested that refusers are prone to anxiety and cope with their present distress by maintaining the belief that their lives are determined by fate or religious convictions. An intervention approach that fosters mastery over the cancer experience is advocated. (8 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献