全文获取类型
收费全文 | 5029篇 |
免费 | 254篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 30篇 |
综合类 | 3篇 |
化学工业 | 927篇 |
金属工艺 | 53篇 |
机械仪表 | 49篇 |
建筑科学 | 204篇 |
矿业工程 | 4篇 |
能源动力 | 89篇 |
轻工业 | 534篇 |
水利工程 | 56篇 |
石油天然气 | 8篇 |
无线电 | 296篇 |
一般工业技术 | 811篇 |
冶金工业 | 1694篇 |
原子能技术 | 17篇 |
自动化技术 | 510篇 |
出版年
2023年 | 34篇 |
2022年 | 70篇 |
2021年 | 111篇 |
2020年 | 74篇 |
2019年 | 77篇 |
2018年 | 105篇 |
2017年 | 105篇 |
2016年 | 116篇 |
2015年 | 115篇 |
2014年 | 133篇 |
2013年 | 252篇 |
2012年 | 226篇 |
2011年 | 382篇 |
2010年 | 281篇 |
2009年 | 244篇 |
2008年 | 310篇 |
2007年 | 288篇 |
2006年 | 240篇 |
2005年 | 213篇 |
2004年 | 173篇 |
2003年 | 154篇 |
2002年 | 154篇 |
2001年 | 114篇 |
2000年 | 97篇 |
1999年 | 94篇 |
1998年 | 135篇 |
1997年 | 127篇 |
1996年 | 91篇 |
1995年 | 87篇 |
1994年 | 72篇 |
1993年 | 81篇 |
1992年 | 39篇 |
1991年 | 19篇 |
1990年 | 42篇 |
1989年 | 42篇 |
1988年 | 31篇 |
1987年 | 30篇 |
1986年 | 28篇 |
1985年 | 23篇 |
1984年 | 23篇 |
1983年 | 22篇 |
1982年 | 15篇 |
1981年 | 17篇 |
1980年 | 12篇 |
1979年 | 13篇 |
1977年 | 14篇 |
1976年 | 31篇 |
1975年 | 21篇 |
1974年 | 10篇 |
1972年 | 9篇 |
排序方式: 共有5285条查询结果,搜索用时 15 毫秒
101.
E. A. Johnson H. F. Lam L. S. Katafygiotis J. L. Beck 《Canadian Metallurgical Quarterly》2004,130(1):3-15
Structural health monitoring (SHM) is a promising field with widespread application in civil engineering. Structural health monitoring has the potential to make structures safer by observing both long-term structural changes and immediate postdisaster damage. However, the many SHM studies in the literature apply different monitoring methods to different structures, making side-by-side comparison of the methods difficult. This paper details the first phase in a benchmark SHM problem organized under the auspices of the IASC–ASCE Structural Health Monitoring Task Group. The scale-model structure adopted for use in this benchmark problem is described. Then, two analytical models based on the structure—one a 12 degree of freedom (DOF) shear-building model, the other a 120-DOF model, both finite element based—are given. The damage patterns to be identified are listed as well as the types and number of sensors, magnitude of sensor noise, and so forth. MATLAB computer codes to generate the response data for the various cases are explained. The codes, as well as details of the ongoing Task Group activities, are available on the Task Group web site at 〈http://wusceel.cive.wustl.edu/asce.shm/〉. 相似文献
102.
Nigg Joel T.; Blaskey Lisa G.; Stawicki Julie Ann; Sachek Jennifer 《Canadian Metallurgical Quarterly》2004,113(4):614
Neurogenetic models predict neuropsychological weaknesses in the relatives of children with attention-deficit/ hyperactivity disorder (ADHD). The authors examined executive and regulatory measures in 386 relatives (307 parents, 79 siblings) of children with ADHD combined type, ADHD inattentive type, and controls. Predicted deficits were seen on trailmaking (relatives of ADHD combined type only), stop-signal reaction times (relatives of girls only), and response variability (mothers only) but not on naming or output speed. Effects generally held, even with relatives' ADHD status controlled. A neuropsychologically impaired subgroup of children with ADHD had relatives with clear neuropsychological weaknesses. The authors conclude that a neurogenetic model of ADHD etiology is supportable only for a subset of executive functions and that neuropsychological heterogeneity warrants more examination in ADHD. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
103.
El-Bassel Nabila; Gilbert Louisa; Frye Victoria; Wu Elwin; Go Hyun; Hill Jennifer; Richman Beverly L. 《Canadian Metallurgical Quarterly》2004,18(2):180
Although several studies have examined the relationship between intimate partner violence (IPV) and drug use among women in drug treatment programs, more information is needed to delineate differences, as a function of the specific drug used. Data from a random sample of 416 women attending methadone programs were analyzed to elucidate the differential associations between IPV and use of the following: marijuana only, cocaine only, heroin only, or cocaine and heroin. Prevalence of IPV among this sample far exceeded estimates from the general population. After adjusting for sociodemographic variables, use of cocaine only was significantly associated with an increased likelihood of experiencing IPV compared with no drug use. Similar results were found for women using both cocaine and heroin. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
104.
Birch Cheryl D.; Stewart Sherry H.; Wall Anne-Marie; McKee Sherry A.; Eisnor Shondalee J.; Theakston Jennifer A. 《Canadian Metallurgical Quarterly》2004,18(3):231
This study investigated whether exposure to musical mood induction procedures (MMIP) differentially increases the strength of specific alcohol expectancies for coping motivated (CM) versus enhancement motivated (EM) drinkers. Participants were 86 undergraduates who had elevated scores on either the CM or EM subscale of the Drinking Motives Questionnaire (M. L. Cooper, 1994). Participants were randomly assigned to either a positive or negative mood condition. The Alcohol Craving Questionnaire (E. G. Singleton, S. T. Tiffany, & J. E. Henningfield, 1994) was administered at baseline and after MMIP to assess phasic changes in alcohol expectancy strength. Consistent with hypotheses, only CM drinkers in the negative mood condition reported increased relief expectancies, and only EM drinkers in the positive mood condition reported increased reward expectancies. Theoretical and clinical implications are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
105.
The authors asked whether there is evidence to support the existence of the vocabulary spurt, an increase in the rate of word learning that is thought to occur during the 2nd year of life. Using longitudinal data from 38 children, they modeled the rate of word learning with two functions, one with an inflection point (logistic), which would indicate a spurt, and one without an inflection point (quadratic). Comparing the fits of these two functions using likelihood ratios, they found that just 5 children had a better logistic fit, which indicated that these children underwent a spurt. The implications for theories of cognitive and language development are considered. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
106.
Beardsley Patrick M.; Aceto Mario D.; Cook Charles D.; Bowman Edward R.; Newman Jennifer L.; Harris Louis S. 《Canadian Metallurgical Quarterly》2004,12(3):163
Despite oxycodone's (4,5-epoxy-14-hydroxy-3-methoxy-17-methylmorphinan-6-one) history of clinical use and the attention it has received as a drug of abuse, few reports have documented its pharmacology's relevance to its abuse or its mechanism of action. The purposes of the present study were to further characterize the analgesic effects of oxycodone, its mechanism of action, and its effects in terms of its relevance to its abuse liability. The results indicate that oxycodone had potent antinociceptive effects in the mouse paraphenylquinone writhing, hot-plate, and tail-flick assays, in which it appeared to be acting as a μ-opioid receptor agonist. It generalized to the heroin discriminative stimulus and served as a positive reinforcer in rats and completely suppressed withdrawal signs in morphinedependent rhesus monkeys. These results suggest that the analgesic and abuse liability effects of oxycodone are likely mediated through μ-opioid receptors and provide the first laboratory report of its discriminative stimulus, reinforcing, and morphine cross-dependency effects. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
107.
Read Jennifer P.; Wood Mark D.; Lejuez C. W.; Palfai Tibor P.; Slack Morgan 《Canadian Metallurgical Quarterly》2004,12(4):298
Examinations of gender differences in alcohol expectancies among college drinkers typically have used self-report measures to assess single expectancy dimensions and often have been confounded by drinking level. This study examined gender differences in alcohol expectancies using 2 assessment methods. College students (N = 88) completed self-report questionnaires, including expectancy likelihood and subjective evaluation endorsements of expectancies, and a computerized expectancy accessibility task. Expectancy accessibility and endorsement were modestly correlated, with higher alcohol consumption and female gender linked to greater accessibility and endorsement of social enhancement expectancies. Gender moderated the relation between consumption and sociability expectancy accessibility; among men, heavier drinking was associated with more rapid activation of expectancies. Findings suggest complexity in associations among these variables and underscore the need to capture the multidimensionality of the expectancy construct and its relationship to alcohol use. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
108.
Goldsmith Rachel E.; Barlow M. Rose; Freyd Jennifer J. 《Canadian Metallurgical Quarterly》2004,41(4):448
Levels of awareness for trauma and their consequences for research, treatment, and prevention within professional psychology and society are considered. When people must endure chronically traumatic environments, it may be adaptive to isolate from awareness information that would produce cognitive dissonance and threaten necessary relationships. Unawareness may also facilitate functioning in environments that invalidate the prevalence and impact of trauma. In addition, characteristics of the posttraumatic environment can promote or impede individuals' awareness of trauma and their psychological functioning. Though often initially adaptive, unawareness for trauma is linked to intergenerational transmission of trauma and its effects and may preclude public and professional attention to trauma treatment and prevention. Understanding the processes through which individuals become unaware or aware of traumatic experience is therefore essential to conducting effective psychotherapy with trauma survivors. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
109.
H.H GatzenM Beck 《Wear》2003,254(9):907-910
With increasing activities on micro electro-mechanical systems (MEMS) type microactuators, there is a growing need in understanding the tribological properties of silicon, the most commonly used wafer material for those devices. In particular, it is of interest if single crystal silicon used in microactuators exposed to rather low vertical loads is subject to wear. Therefore, wear tests using monocrystalline silicon on both sides of the tribological interface were conducted.A classic way to measure wear on sliders in contact with a tape or a rotating disk is to create an imprint using a Berkovich diamond tip mounted on a picoindenter. However, in our case we used a different approach. We created three studs on a slider’s surface by recessing the material outside the studs through an ion milling process. During the wear tests, the studs wore off. By measuring the remaining stud height, the wear volume could be determined at any point in time. The tests were performed on a pin on disk tester with a gimbaled slider to realize a flat on flat contact and a rather low normal force of 30 mN. 相似文献
110.
Ahn Woo-Young; Rass Olga; Fridberg Daniel J.; Bishara Anthony J.; Forsyth Jennifer K.; Breier Alan; Busemeyer Jerome R.; Hetrick William P.; Bolbecker Amanda R.; O'Donnell Brian F. 《Canadian Metallurgical Quarterly》2011,120(4):911
Patients with bipolar disorder (BD) and schizophrenia (SZ) often show decision-making deficits in everyday circumstances. A failure to appropriately weigh immediate versus future consequences of choices may contribute to these deficits. We used the delay discounting task in individuals with BD or SZ to investigate their temporal decision making. Twenty-two individuals with BD, 21 individuals with SZ, and 30 healthy individuals completed the delay discounting task along with neuropsychological measures of working memory and cognitive function. Both BD and SZ groups discounted delayed rewards more steeply than did the healthy group even after controlling for current substance use, age, gender, and employment. Hierarchical multiple regression analyses showed that discounting rate was associated with both diagnostic group and working memory or intelligence scores. In each group, working memory or intelligence scores negatively correlated with discounting rate. The results suggest that (a) both BD and SZ groups value smaller, immediate rewards more than larger, delayed rewards compared with the healthy group and (b) working memory or intelligence is related to temporal decision making in individuals with BD or SZ as well as in healthy individuals. (PsycINFO Database Record (c) 2011 APA, all rights reserved) 相似文献