全文获取类型
收费全文 | 1863篇 |
免费 | 32篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 25篇 |
综合类 | 9篇 |
化学工业 | 255篇 |
金属工艺 | 21篇 |
机械仪表 | 19篇 |
建筑科学 | 103篇 |
矿业工程 | 1篇 |
能源动力 | 41篇 |
轻工业 | 169篇 |
水利工程 | 10篇 |
石油天然气 | 28篇 |
无线电 | 65篇 |
一般工业技术 | 191篇 |
冶金工业 | 782篇 |
原子能技术 | 7篇 |
自动化技术 | 170篇 |
出版年
2023年 | 13篇 |
2022年 | 26篇 |
2021年 | 43篇 |
2020年 | 18篇 |
2019年 | 30篇 |
2018年 | 22篇 |
2017年 | 20篇 |
2016年 | 24篇 |
2015年 | 29篇 |
2014年 | 35篇 |
2013年 | 92篇 |
2012年 | 57篇 |
2011年 | 68篇 |
2010年 | 53篇 |
2009年 | 80篇 |
2008年 | 93篇 |
2007年 | 84篇 |
2006年 | 59篇 |
2005年 | 71篇 |
2004年 | 63篇 |
2003年 | 64篇 |
2002年 | 46篇 |
2001年 | 47篇 |
2000年 | 42篇 |
1999年 | 50篇 |
1998年 | 65篇 |
1997年 | 52篇 |
1996年 | 67篇 |
1995年 | 40篇 |
1994年 | 42篇 |
1993年 | 46篇 |
1992年 | 31篇 |
1991年 | 11篇 |
1990年 | 29篇 |
1989年 | 36篇 |
1988年 | 18篇 |
1987年 | 20篇 |
1986年 | 21篇 |
1985年 | 21篇 |
1984年 | 23篇 |
1983年 | 18篇 |
1982年 | 17篇 |
1981年 | 22篇 |
1980年 | 12篇 |
1979年 | 10篇 |
1978年 | 10篇 |
1977年 | 8篇 |
1976年 | 19篇 |
1975年 | 7篇 |
1972年 | 4篇 |
排序方式: 共有1896条查询结果,搜索用时 0 毫秒
1.
Myers Nicholas D.; Payment Craig A.; Feltz Deborah L. 《Canadian Metallurgical Quarterly》2004,8(3):182
This study examined reciprocal relationships between collective efficacy and team performance over a season of competition in women's intercollegiate ice hockey within weekends where the opponent was constant for 2 games. Collective efficacy beliefs within 12 teams were assessed prior to both games for at least 7 weekends. Team performance indexes produced an overall measure of performance for each game. The average influence of Saturday collective efficacy on Saturday performance was moderate and positive after controlling for Friday performance. The average influence of Friday performance on Saturday collective efficacy was small and positive after removing the influence of Friday collective efficacy from Friday performance. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
2.
Some therapists hold that the Bobo and other aggressive toys should be excluded from the playroom as they elicit acting-out behavior that is transferred to the world outside the playroom. However, many therapists view the inclusion of these items as imperative elements that facilitate positive growth and maturation in the child. Interviews with authorities in the field of play therapy support the position that the inclusion of the Bobo is not only useful, but a therapeutic necessity. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
3.
Friendship affects individual and organizational well-being through direct relations, social positions, and complex network structures. In this study, the authors use longitudinal data from 2 groups of master's of business administration students to increase understanding of how friendship networks develop. The authors propose and test a dynamic model in which attribute similarity facilitates dyadic friendship ties, as well as similar network centrality and social position; early friendship increases later similarity in structural position and centrality; and early structural similarity enhances the likelihood of future friendship. Findings largely supported the model, demonstrating how homophily and early social contacts can jointly shape maturing friendship networks. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
4.
A value-based test is presented for economic screening of electric utility demand-side management (DSM) programs. The widely used least cost test is valid if the programs do not alter the amount or value of energy services provided to customers. But, in general, DSM programs have such effects and, as a result, the value consumers receive is changed. A more general economic efficiency test, the most value test, provides a practical method for considering the effects of DSM on customer value. The version presented allows for multiple load periods and can account for rate impacts on several customer classes. Four typical DSM programs are evaluated as illustrations 相似文献
5.
OBJECTIVES: 1) To quantify the frequency of underrecognized Neisseria gonorrhoeae and Chlamydia trachomatis cervical infections in women tested in the ED, 2) to describe and compare the characteristics of those treated and not treated during the initial visit, and 3) to quantify the delay interval until treatment was provided. METHODS: A 2-year, retrospective consecutive case series was performed from June 1, 1992, to May 31, 1994. There were 148 women with > or = 1 discrete occurrence of culture-proven cervical N. gonorrhoeae or C. trachomatis infection studied. All the patients were evaluated in a university-affiliated, tertiary care hospital-based ED with a large rural referral area. The main outcome measures were the proportions of patients with positive cultures both treated and not treated in the ED, the clinical characteristics of each group, and the proportion remaining untreated or experiencing treatment delays of > 2 weeks after attempted phone, mail, and public health follow-up. RESULTS: Of 157 occurrences of positive cultures for N. gonorrhoeae or C. trachomatis, 86 (53%) were treated with a regimen suggested by the CDC prior to ED release. The proportion of women with isolated C. trachomatis infections that were underrecognized and untreated initially was larger than the proportions with isolated N. gonorrhoeae or combined infections (79% vs 27% and 53%, respectively, p < 0.0001). Women with findings suggestive of advanced disease (history of fever or chills, or examination evidence of temperature > 38 degrees C, purulent vaginal discharge, or any uterine/salpinx/ovarian tenderness) were more often recognized and treated with appropriate antibiotics initially (p = 0.02 to < 0.00001 for all). After phone, mail, and public health follow-up, treatment could not be documented for 25% of the occurrences, in all cases due to an inability to locate the patient. An additional 20% of the women did not receive treatment for 14-60 days. CONCLUSIONS: In this population, both N. gonorrhoeae and C. trachomatis cervical infections are frequently underrecognized in the ED, with isolated C. trachomatis infections associated with significantly higher proportions of underrecognition. Many affected women remain untreated for extended intervals, creating public and individual health risks. Improved point of contact detection, follow-up, and treatment policies are needed to limit these risks. 相似文献
6.
Examined the job performance of 420 credit managers (mean age at hiring 25 yrs) from a large finance company who either quit their job, were fired, or were promoted to a higher position in the company. Six biographical variables and 12 performance appraisal scores accumulated from data in employee files were used in a cross-validated multiple discriminant analysis to predict membership in the 3 classification groups. Results reveal a systematic relation between the performance appraisal variables and the classification groups: The performance of promoted Ss was significantly superior to that of Ss who quit, which in turn was significantly superior to the performance of the fired Ss. 18 discriminating variables accounted for a 46.7% hit rate in group membership. Findings are discussed in the context of research on performance antecedents of voluntary and involuntary turnover, as well as the feedback properties of performance appraisal information. It is suggested that no single performance–turnover relation exists. (14 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
7.
Reports a meta-analysis comparing the size of semantic priming effects on young and older adults' lexical decision and pronunciation latency. The analysis included 15 studies with 49 conditions varying the semantic relatedness of a prime stimulus (single word or whole sentence) and a target word. An effect-size analysis on the difference between young and older adults' semantic priming effect (unrelated minus related latency) indicated that semantic priming effects are reliably larger for older than for young adults. There was no evidence for nonhomogeneity in this age difference across the different conditions. The relationship between young and older adults' semantic priming effects was described by a function with a positive intercept and a slope of 1.0. This pattern of findings favors aging models postulating process-specific slowing rather than general cognitive slowing. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
8.
Richard D. Dick William L. Fourney Deborah J. Goodings Chaun‐Ping Lin Leonhard E. Bernold 《Canadian Metallurgical Quarterly》1992,5(1):59-69
The utilization of explosives for excavation on the lunar surface is under serious consideration as a part of the design for construction of temporary and permanent bases. An excavation research program has shown that small‐scale explosives blasting in a lunar‐soil simulant will greatly reduce the digging forces required for scoop and dragline excavators. Some crater‐blasting parameters were determined for the lunar soil simulant at one Earth gravity and at 10 Earth gravities using a centrifuge. The size of the craters produced at 10 Earth gs matched those formed at one earth g by scaling according to the weight of the explosive. These data can be applied to explosive‐excavation problems such as habitat construction, burial of nuclear power sources, and the rapid construction of shelters remote from the main base to shield against solar‐flare activity. 相似文献
9.
Kindergartners, 3rd, and 6th graders chose classmates whom they would and would not like to have on their team for an academic contest and as playmates. Ss also rated their classmates on likableness and academic ability. At all ages, children's choices for the academic competition and the play situation were significantly associated with their ratings of their classmates' academic and social competence, respectively. Ss typically referred to academic abilities to explain their teammate choices for the academic contest and to social competence or friendship to explain playmate choices. Questions about the stability of classmates' academic and social competencies revealed that not until 6th grade did Ss indicate that there are limits in the degree to which academic and social competencies could improve with effort. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
10.
Hishinuma Earl S.; Else 'Iwalani R. N.; Chang Janice Y.; Goebert Deborah A.; Nishimura Stephanie T.; Choi-Misailidis Soojean; Andrade Naleen N. 《Canadian Metallurgical Quarterly》2006,21(3):286
School psychologists are generally not provided with the knowledge and skills to address both educational and psychosocial issues of Asian American and Pacific Islander students. The present study is the first of its kind in examining 36 independent (i.e., demographic, social, cultural, psychological) variables in association with four school outcomes (i.e., grade point average, absences, suspensions, and school infractions) with a large sample of Caucasian, Filipino, Native Hawaiian, Japanese, mixed/non-Hawaiian, and "other" Hawai'i high school students (N = 2,833). Given the relatively unique sample in question and the sheer number of variables, an exploratory approach was utilized with the goal of determining the most robust independent variables, with the unique inclusion of Hawaiian cultural identification. A cross-validation technique was used, whereby stepwise regressions were performed for each of two cross-validation samples; only common variables were retained in a final stepwise model for each of the four school outcomes. The results indicated that, remarkably, substance use accounted for the most variance (i.e., 8.4% -16.1 %) in the four school measures. Further analyses detailed the relationship, including the finding that smoking cigarettes regularly, accounted for the most variance compared to the other five substance use items. Further research and implications of the findings are discussed, including the need for prevention and intervention programs that incorporate substance use as a component, both within and outside of school environments. (PsycINFO Database Record (c) 2011 APA, all rights reserved) 相似文献