全文获取类型
收费全文 | 3775篇 |
免费 | 181篇 |
国内免费 | 110篇 |
专业分类
电工技术 | 62篇 |
技术理论 | 1篇 |
综合类 | 172篇 |
化学工业 | 470篇 |
金属工艺 | 110篇 |
机械仪表 | 53篇 |
建筑科学 | 294篇 |
矿业工程 | 36篇 |
能源动力 | 66篇 |
轻工业 | 557篇 |
水利工程 | 149篇 |
石油天然气 | 48篇 |
武器工业 | 2篇 |
无线电 | 139篇 |
一般工业技术 | 238篇 |
冶金工业 | 1304篇 |
原子能技术 | 14篇 |
自动化技术 | 351篇 |
出版年
2024年 | 10篇 |
2023年 | 54篇 |
2022年 | 150篇 |
2021年 | 161篇 |
2020年 | 87篇 |
2019年 | 93篇 |
2018年 | 84篇 |
2017年 | 94篇 |
2016年 | 112篇 |
2015年 | 102篇 |
2014年 | 128篇 |
2013年 | 145篇 |
2012年 | 159篇 |
2011年 | 324篇 |
2010年 | 257篇 |
2009年 | 203篇 |
2008年 | 222篇 |
2007年 | 273篇 |
2006年 | 212篇 |
2005年 | 185篇 |
2004年 | 179篇 |
2003年 | 167篇 |
2002年 | 119篇 |
2001年 | 104篇 |
2000年 | 43篇 |
1999年 | 44篇 |
1998年 | 39篇 |
1997年 | 28篇 |
1996年 | 27篇 |
1995年 | 28篇 |
1994年 | 26篇 |
1993年 | 20篇 |
1992年 | 21篇 |
1991年 | 10篇 |
1990年 | 10篇 |
1989年 | 16篇 |
1988年 | 11篇 |
1987年 | 8篇 |
1986年 | 8篇 |
1985年 | 10篇 |
1984年 | 13篇 |
1983年 | 7篇 |
1982年 | 11篇 |
1965年 | 5篇 |
1964年 | 6篇 |
1961年 | 6篇 |
1959年 | 3篇 |
1956年 | 4篇 |
1955年 | 5篇 |
1954年 | 4篇 |
排序方式: 共有4066条查询结果,搜索用时 15 毫秒
131.
研究盐渍榨菜在流通过程中环境因素:流通温度、流通湿度、光照强度、流通时间作用下的品质变化规律,采用响应面法得出各因素对盐渍榨菜品质影响,并确定相应的数学模型,从而得出影响因素与榨菜品质变化的关系. 相似文献
132.
《Ergonomics》2012,55(7):859-873
Psychophysical methodology has been used to develop guidelines for lifting and more recently similar methods have been applied to repetitive upper limb movements. While a range of cycle times are usually used, there is often no control for duty cycle. The purpose of this paper is to present psychophysically determined acceptable torques for a common upper limb task, with both cycle time and duty cycle conditions set by the researcher. Eight female participants, sitting at adjustable workstations, performed a simulated in-line screw running task. A computer-controlled torque motor applied a torque every 3, 6, 12 or 20?s with a duty cycle of 25, 50 or 83%. The participants worked with one set of conditions each day and self-selected the highest torque that they felt was acceptable without developing undue pain and discomfort. Duty cycle was found to significantly affect the amount of torque selected. With duty cycle controlled, cycle time was no longer found to have any significant effect on selected torque. Acceptable torques for 25, 50 and 83% duty cycles were 1.09, 0.9 and 0.73 Nm. Discomfort and stiffness were concentrated on the back of the hand and on the thumb web. These findings suggest that increased perception of discomfort with increased frequency (decreased cycle time) may be related to decreased rest/recovery time for muscles. 相似文献
133.
This paper examines an approach to modeling the relationship between perceived acceptable work exposures and physical stressors in upper-extremity tasks using psychophysical methods. Several years of laboratory-based studies and results from a variety of simulated work tasks and task elements are summarized. The original impetus of these studies was founded in the pioneering work and successful application of psychophysical methods applied to manual materials handling tasks (e.g., lifting) generally beginning in the 1960s and 1970s. This approach provided unique and feasible solutions to work design problems involving exposure to the hazard of cumulative trauma. Presently, these methods were adapted to studying common upper-extremity tasks and task elements. Results provide conclusive evidence of the impact of required posture, force, gender and other variables on acceptable task frequency. These results and the psychophysical method in general, may be particularly helpful in establishing realistic and reasonable work design guidelines when workers are exposed to multiple, simultaneous hazards such as force, frequency, with deviated posture, etc, and in the absence of well-defined biomechanical or physiological-based models. Finally, a review of psychophysical theory and methods which can be applied to a wide range of occupational activities is provided. 相似文献
134.
135.
ObjectivesThis paper examines the workflow of sleep physicians during a patient consultation and how an innovative clinical decision support system (CDSS) provides efficiency and effectiveness gains.MethodsThe CDSS tools consisted of two input applications for patient data, with a knowledge based decision support system developed participatively with physicians and an international panel. An argument tree approach was used to produce diagnostic explanations and an evidence-based report for the physician using medically correct and shared terminology. A usability evaluation using a qualitative approach was carried out to ensure that the CDSS met the physicians׳ information needs, as well as the wider needs of a Sleep Investigation Unit.ResultsThe physicians found the CDSS both useful and usable with clear applications in triage and diagnostic decision-making, and in patient education.ConclusionThe CDSS both reduces the time and number of visits needed for consultations, and helps focus consultation on better individual patient care through informed explanation of diagnostic and treatment decisions. 相似文献
136.
火花塞间隙的大小,直接关系到两极间跳火的强弱。间隙过小会使火花变弱,也更容易使两点击发生跨连,不利于发动机工作,其间隙过大,不易使两级产生火花,所需点火能量就愈大。 相似文献
137.
以由AAu8和ACu4干基因组成的AuCuI(AAu Cu8 A4)化合物的无序化实验路径为例,介绍了3个发现和1个方法。发现AuCuI(AAuCu8A4)化合物抗拒温度变化保持结构稳定性的能力归因于AAu8和ACu4基因的势阱深度远超过其振动能,这导致其无序化实验路径是亚平衡的;发现AuCuI(AAu Cu8 A4)适应温度变化改变结构的原子移动新机制是合金基因的"共振激活-同步交换"机制,这导致无序化是非均匀性和递次性的亚平衡转变;发现无序化过程中存在跳变有序度,导致存在跳变温度和升温速度增加跳变温度降低的"逆反效应",即所谓的"Retro效应"。采用实验混合焓路径法,建立了一整套亚平衡全息网络路径图。 相似文献
138.
Dowell Lauren R.; Mahone E. Mark; Mostofsky Stewart H. 《Canadian Metallurgical Quarterly》2009,23(5):563
Children with autism often have difficulty performing skilled movements. Praxis performance requires basic motor skill, knowledge of representations of the movement (mediated by parietal regions), and transcoding of these representations into movement plans (mediated by premotor circuits). The goals of this study were (a) to determine whether dyspraxia in autism is associated with impaired representational (“postural”) knowledge and (b) to examine the contributions of postural knowledge and basic motor skill to dyspraxia in autism. Thirty-seven children with autism spectrum disorder (ASD) and 50 typically developing (TD) children, ages 8–13, completed (a) an examination of basic motor skills, (b) a postural knowledge test assessing praxis discrimination, and (c) a praxis examination. Children with ASD showed worse basic motor skill and postural knowledge than did controls. The ASD group continued to show significantly poorer praxis than did controls after accounting for age, IQ, basic motor skill, and postural knowledge. Dyspraxia in autism appears to be associated with impaired formation of spatial representations, as well as transcoding and execution. Distributed abnormality across parietal, premotor, and motor circuitry, as well as anomalous connectivity, may be implicated. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
139.
Vinnars Bo; Thorm?hlen Barbro; Gallop Robert; Norén Kristina; Barber Jacques P. 《Canadian Metallurgical Quarterly》2009,46(3):362
Studies involving patients with personality disorders (PDs) have not focused on improvement of core aspects of the PD. The authors examined changes in quality of object relations, interpersonal problems, psychological mindedness, and personality traits in a sample of 156 patients with Diagnostic and Statistical Manual of Mental Disorders (4th ed.) PD diagnoses being randomized to either manualized or nonmanualized dynamic psychotherapy. Effect sizes adjusted for symptomatic change and reliable change indices were calculated. The authors found that both treatments were equally effective at reducing personality pathology. Only in neuroticism did the nonmanualized group do better during the follow-up period. The largest improvement was found in quality of object relations. For the remaining variables, only small and clinically insignificant magnitudes of change were found. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
140.
Numerous studies indicate deficient time estimation in individuals with attention-deficit/hyperactivity disorder (ADHD). Several hypotheses have been raised to explain this deficit including delay aversion, vulnerability to nontemporal distractions, deficient working memory, as well as pure deficit in temporal processing. To test the different hypotheses, adults with or without ADHD performed a prospective time-estimation task under different conditions: with or without nontemporal distraction; and with or without increased load of working memory. Such design was used to rule out the effect of motor control and to manipulate the hypothesized mechanisms of working memory and attention to nontemporal stimuli. The authors report that compared with the control group, adults with ADHD showed greater and more variable deviation in time estimation. In addition, the magnitude of time estimation was affected by allocation of attention to nontemporal stimuli and by load of working memory. The intraindividual variability of time estimation was only partially accounted for by load of working memory. These findings suggest that the ADHD-associated deficit in prospective time estimation is not attributable to special attention to nontemporal stimuli or compromised working memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献