全文获取类型
收费全文 | 2793篇 |
免费 | 163篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 12篇 |
综合类 | 3篇 |
化学工业 | 704篇 |
金属工艺 | 31篇 |
机械仪表 | 16篇 |
建筑科学 | 131篇 |
矿业工程 | 4篇 |
能源动力 | 46篇 |
轻工业 | 482篇 |
水利工程 | 28篇 |
石油天然气 | 19篇 |
武器工业 | 1篇 |
无线电 | 130篇 |
一般工业技术 | 478篇 |
冶金工业 | 504篇 |
原子能技术 | 18篇 |
自动化技术 | 351篇 |
出版年
2023年 | 13篇 |
2022年 | 45篇 |
2021年 | 118篇 |
2020年 | 59篇 |
2019年 | 47篇 |
2018年 | 59篇 |
2017年 | 88篇 |
2016年 | 86篇 |
2015年 | 85篇 |
2014年 | 109篇 |
2013年 | 157篇 |
2012年 | 162篇 |
2011年 | 195篇 |
2010年 | 148篇 |
2009年 | 129篇 |
2008年 | 162篇 |
2007年 | 160篇 |
2006年 | 144篇 |
2005年 | 102篇 |
2004年 | 87篇 |
2003年 | 86篇 |
2002年 | 67篇 |
2001年 | 54篇 |
2000年 | 33篇 |
1999年 | 51篇 |
1998年 | 48篇 |
1997年 | 46篇 |
1996年 | 39篇 |
1995年 | 26篇 |
1994年 | 35篇 |
1993年 | 37篇 |
1992年 | 28篇 |
1991年 | 19篇 |
1990年 | 28篇 |
1989年 | 22篇 |
1988年 | 20篇 |
1987年 | 21篇 |
1986年 | 17篇 |
1985年 | 21篇 |
1984年 | 8篇 |
1983年 | 16篇 |
1982年 | 9篇 |
1981年 | 4篇 |
1980年 | 14篇 |
1979年 | 6篇 |
1978年 | 5篇 |
1977年 | 10篇 |
1974年 | 7篇 |
1973年 | 4篇 |
1960年 | 5篇 |
排序方式: 共有2958条查询结果,搜索用时 31 毫秒
61.
Hoelzl C Lorenz O Haudek V Gundacker N Knasmüller S Gerner C 《Proteomics. Clinical applications》2008,2(1):108-117
Epidemiological studies indicate a correlation of cruciferous vegetables consumption with reduced incidence of cancer. This study was designed to investigate molecular mechanisms, which may help to understand the beneficial effects of Brussels sprout consumption. In order to avoid the limitations of in vitro model systems, we performed a dietary intervention study with five participants. We investigated, whether sprout consumption affects the proteome profile of primary white blood cells. In order to achieve maximal sensitivity in detecting specific adaptive proteome alterations, we metabolically labelled freshly isolated cells in the presence of 35S‐methionine/cysteine and performed autoradiographic quantification of protein synthesis. Proteins were separated by 2‐DE and spots of interest were cut out, digested and identified by MS. After the intervention, we found a significant up‐regulation of the synthesis of manganese superoxide dismutase (1.56‐fold) and significant down‐regulation of the synthesis of heat shock 70 kDa protein (hsp70; 2.27‐fold). Both proteins play a role in malignant transformation of cells. Hsp‐70 is involved in the regulation of apoptosis, which leads to elimination of cancer cells, while SOD plays a key role in protection against reactive oxygen species mediated effects. Our findings indicate that the alteration of the synthesis of these proteins may be involved in the anticarcinogenic effects of cruciferous vegetables, which was observed in earlier laboratory studies with animals. 相似文献
62.
Knowledge is increasingly recognized as the key resource of business. Digital networks provide access to vast amounts of data and information but knowledge management tools and systems are required to translate this in a meaningful way. Knowledge management initiatives are unlikely to be successful unless they are integrated with business strategy, and related to the development of the core capabilities of the organisation. Sharing the discovery and synthesis of intellectual activity involves the creation of knowledge communities of practice. There is much evidence of commercially inspired corporate initiatives in this direction across all industrial sectors: leveraging existing intellectual capital; sharing best practice across multiple locations; data mining to build customer relationships; and creating knowledge networks to allow state–of–the–art solutions in professional services. 相似文献
63.
64.
Sreng J Lécuyer A Mégard C Andriot C 《IEEE transactions on visualization and computer graphics》2006,12(5):1013-1020
This paper describes a set of visual cues of contact designed to improve the interactive manipulation of virtual objects in industrial assembly/maintenance simulations. These visual cues display information of proximity, contact and effort between virtual objects when the user manipulates a part inside a digital mock-up. The set of visual cues encloses the apparition of glyphs (arrow, disk, or sphere) when the manipulated object is close or in contact with another part of the virtual environment. Light sources can also be added at the level of contact points. A filtering technique is proposed to decrease the number of glyphs displayed at the same time. Various effects--such as change in color, change in size, and deformation of shape- can be applied to the glyphs as a function of proximity with other objects or amplitude of the contact forces. A preliminary evaluation was conducted to gather the subjective preference of a group of participants during the simulation of an automotive assembly operation. The collected questionnaires showed that participants globally appreciated our visual cues of contact. The changes in color appeared to be preferred concerning the display of distances and proximity information. Size changes and deformation effects appeared to be preferred in terms of perception of contact forces between the parts. Last, light sources were selected to focus the attention of the user on the contact areas. 相似文献
65.
O'Brien S Luo Y Wu C Petrak M Bohm E Brandt JM 《Proceedings of the Institution of Mechanical Engineers. Part H, Journal of engineering in medicine》2012,226(3):235-245
The micromotion at the interface between the polyethylene tibial insert and metal tibial tray [corrected] in modular total knee replacements [corrected] has been shown to contribute to wear particle-induced osteolysis and may [corrected] cause implant failure. Therefore, studying the design parameters that are involved in the backside wear process is an important task that may lead to improvement in new total knee replacements. In the present study, a finite element model was developed to predict the backside micromotion along the entire modular interface. Both the linear elastic constitutive model and non-linear J2-plasticity constitutive model were considered in the finite element model for polyethylene and were corroborated against published results obtained from displacement controlled knee simulator wear tests. The finite element simulation with the non-linear J2-plasticity constitutive model was able to predict backside micromotion [corrected] more accurately than the simulation with the linear elastic constitutive model. [corrected] The developed finite element model (including the non-linear J2-plasticity constitutive model) was then applied to assess the effects of the tibial tray locking mechanism design (dovetails versus fullperipheral [corrected] design) and different levels of interference fit on insert micromotion. The developed finite element model, implementing the non-linear J2-plasticity constitutive model, was shown to successfully predict clinical amounts of backside micromotion and could be used for the design and development of total knee replacements for the reduction of backside micromotion and polyethylene [corrected] wear. 相似文献
66.
Riedl T Gemming T Mickel C Eymann K Kirchner A Kieback B 《Microscopy research and technique》2012,75(6):711-719
This article explores the achievable transmission electron microscopy specimen thickness and quality by using three different preparation methods in the case of a high-strength nanocrystalline Cu-Nb powder alloy. Low specimen thickness is essential for spatially resolved analyses of the grains in nanocrystalline materials. We have found that single-sided as well as double-sided low-angle Ar ion milling of the Cu-Nb powders embedded into epoxy resin produced wedge-shaped particles of very low thickness (<10 nm) near the edge. By means of a modified focused ion beam lift-out technique generating holes in the lamella interior large micrometer-sized electron-transparent regions were obtained. However, this lamella displayed a higher thickness at the rim of ≥30 nm. Limiting factors for the observed thicknesses are discussed including ion damage depths, backscattering, and surface roughness, which depend on ion type, energy, current density, and specimen motion. Finally, sections cut by ultramicrotomy at low stroke rate and low set thickness offered vast, several tens of square micrometers uniformly thin regions of ~10-nm minimum thickness. As major drawbacks, we have detected a thin coating on the sections consisting of epoxy deployed as the embedding material and considerable nanoscale thickness variations. 相似文献
67.
Ting Wang Christine Chevallereau Carlos F. Rengifo 《Robotics and Autonomous Systems》2012,60(7):962-977
This paper presents a stable walking control method for a 3D bipedal robot with 14 joint actuators. The overall control law consists of a ZMP (zero moment point) controller, a swing ankle rotation controller and a partial joint angles controller. The ZMP controller guarantees that the stance foot remains in flat contact with the ground. The swing ankle rotation controller ensures a flat foot impact at the end of the swinging phase. Each of these controllers creates 2 constraints on joint accelerations. As a consequence, the partial joint angles controller is implemented to track only 10 independent outputs. These outputs are defined as a linear combination of the 14 joint angles. The most important question addressed in this paper is how this linear combination can be defined in order to ensure walking stability. The stability of the walking gait under closed loop control is evaluated with the linearization of the restricted Poincare map of the hybrid zero dynamics. As a result, the robot can achieve an asymptotically stable and periodic walking along a straight line. Finally, another feedback controller is supplemented to adjust the walking direction of the robot and some examples of the robot steered to walk along different paths with mild curvature are given. 相似文献
68.
Parker Jeffrey G.; Low Christine M.; Walker Alisha R.; Gamm Bridget K. 《Canadian Metallurgical Quarterly》2005,41(1):235
Children's vulnerability to jealousy surrounding their best friends was explored in 2 studies. Study 1 involved 94 adolescents who reported on their friendship jealousy on a newly created measure. Results indicated that the jealousy measure had sound psychometric properties and produced individual differences that were robust over time and free from socially desirable responding. As expected, girls and adolescents with low self-worth reported the greatest friendship jealousy. Study 2 involved 399 young adolescents and extended the measurement of self-report jealousy to a broader age range. In addition, Study 2 included assessments of jealousy provided by friends and other peers. Self- and peer-reported jealousy were only modestly associated and had somewhat distinct correlates. Structural modeling revealed that young adolescents' reputation for friendship jealousy was linked to behaving aggressively and to broader peer adjustment difficulties. Both self- and peer-reported jealousy contributed to loneliness. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
69.
Love John M.; Kisker Ellen Eliason; Ross Christine; Raikes Helen; Constantine Jill; Boller Kimberly; Brooks-Gunn Jeanne; Chazan-Cohen Rachel; Tarullo Louisa Banks; Brady-Smith Christy; Fuligni Allison Sidle; Schochet Peter Z.; Paulsell Diane; Vogel Cheri 《Canadian Metallurgical Quarterly》2005,41(6):885
Early Head Start, a federal program begun in 1995 for low-income pregnant women and families with infants and toddlers, was evaluated through a randomized trial of 3,001 families in 17 programs. Interviews with primary caregivers, child assessments, and observations of parent-child interactions were completed when children were 3 years old. Caregivers were diverse in race-ethnicity, language, and other characteristics. Regression-adjusted impact analyses showed that 3-year-old program children performed better than did control children in cognitive and language development, displayed higher emotional engagement of the parent and sustained attention with play objects, and were lower in aggressive behavior. Compared with controls, Early Head Start parents were more emotionally supportive, provided more language and learning stimulation, read to their children more, and spanked less. The strongest and most numerous impacts were for programs that offered a mix of home-visiting and center-based services and that fully implemented the performance standards early. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
70.
Lee Catherine M.; Beauregard Christine; Bax Karen A. 《Canadian Metallurgical Quarterly》2005,19(2):237
Dual-income parents (N = 122 couples) with an oldest child 18-60 months of age completed the Child-Rearing Disagreements Scale (E. N. Jouriles et al., 1991), the Child Behavior Checklist (T. M. Achenbach & L. A. Rescorla, 2000), and the Verbal Aggression subscale of the Conflicts and Problem-Solving Scale (P. K. Kerig, 1996). Replicating the results of E. N. Jouriles et al. (1991) and extending these findings to daughters and fathers, the authors found links between child-related disagreements and parental ratings of child behavior problems in this low-risk sample. There were no links between fathers' reports of verbal aggression and child behavior problems. Among mothers, however, use of verbal aggression mediated the link between child-related disagreements and ratings of sons' internalizing problems. Verbal aggression did not moderate the link between child-related disagreements and child behavior problems for either mothers or for fathers. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献