首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   646篇
  免费   40篇
电工技术   3篇
化学工业   161篇
金属工艺   4篇
机械仪表   3篇
建筑科学   21篇
矿业工程   1篇
能源动力   11篇
轻工业   98篇
水利工程   5篇
无线电   50篇
一般工业技术   93篇
冶金工业   154篇
原子能技术   6篇
自动化技术   76篇
  2022年   9篇
  2021年   12篇
  2020年   9篇
  2019年   15篇
  2018年   15篇
  2017年   13篇
  2016年   15篇
  2015年   11篇
  2014年   18篇
  2013年   41篇
  2012年   30篇
  2011年   44篇
  2010年   31篇
  2009年   29篇
  2008年   23篇
  2007年   39篇
  2006年   18篇
  2005年   28篇
  2004年   21篇
  2003年   16篇
  2002年   19篇
  2001年   7篇
  2000年   8篇
  1999年   10篇
  1998年   32篇
  1997年   15篇
  1996年   20篇
  1995年   11篇
  1994年   8篇
  1993年   11篇
  1992年   7篇
  1990年   3篇
  1989年   3篇
  1988年   3篇
  1987年   8篇
  1986年   7篇
  1985年   2篇
  1984年   6篇
  1983年   3篇
  1982年   3篇
  1981年   7篇
  1980年   3篇
  1979年   11篇
  1978年   5篇
  1977年   9篇
  1976年   8篇
  1975年   6篇
  1973年   2篇
  1972年   2篇
  1967年   2篇
排序方式: 共有686条查询结果,搜索用时 15 毫秒
31.
In this article, a powder‐bed class of additive manufacturing (AM) is incorporated into the manufacturing of graphene nanocomposite 3D structures. For AM of graphene‐based 3D structures, graphene oxide (GO)/hydroxyapatite (Hap) nanocomposite (GHN) was synthesized at different GO to Hap percentage (wt.%), including 0.2% and 0.4% to develop a printable powder. The synthesized powder was utilized in a powder‐bed AM system to fabricate 3D porous structures of GHN powder. It was shown that at layer thickness of 125 μm and core binder saturation level of 400%, the compressive mechanical strength of the samples with higher content of graphene was improved significantly.  相似文献   
32.
The objective of the present work was to understand how the structural, surface, water vapour and gas barrier properties of wheat gluten (WG) coated paper could be influenced by the features of paper. For this purpose, a surface treated paper (TP) and an untreated paper (UTP) were compared. Penetration of WG-coating into the bulk of paper was more pronounced in UTP than TP. This led to the formation of a significant junction zone resulting in an interpenetrated structure for WG–UTP, suggesting a composite-like structure, while a bi-layer one was obtained for WG–TP. Differences in WG penetration were related to the hydrophilicity, roughness and porosity of the paper used. Even though the extent of penetration did not greatly affect the surface properties (water and oil resistance), the transfer properties (water vapour, O2 and CO2) of WG-coated papers were significantly improved when WG-coating highly penetrated: while the WG–TP behaved as a micro-perforated material, the WG–UTP behaved as WG-film.  相似文献   
33.
Rudolph M. Bell (1985). Holy Anorexia. Epilogue by William N. Davis. Chicago: University of Chicago Press.

Joan Jacobs Brumberg (1988). Fasting Girls: The Emergence of Anorexia Nervosa as a Modern Disease. Cambridge: Harvard University Press.

Caroline Walker Bynum (1987). Holy Feast and Holy Fast: The Religious Significance of Food to Medieval Women. Berkeley: University of California Press.  相似文献   
34.
35.
Due to the increasing importance of modified electrodes for many applications in nanotechnology, including molecular electronics, bioelectronics, and sensors, there is a need to find ways to chemically attach suitable molecular films onto the electrodes. Combining the electroreduction of aryl diazonium salts with the Sonogashira cross‐coupling reaction, a new modular technique to modify electrodes is presented. The new technique allows a wide range of functional groups to be introduced onto electrode surfaces with high surface coverage by the functional subunit. Various organic subunits, including redox chromophores, are successfully attached to platinum electrodes. The corresponding films are characterized using cyclic voltammetry, X‐ray photoelectron spectroscopy, atomic force microscopy, and contact‐angle measurements. The electroreduction of diazonium salts is successfully achieved on a broad variety of conducting and semiconducting surfaces, which shows that the technique is applicable to a broad variety of substrates.  相似文献   
36.
In this paper, we address the issue of designing a theoretically well-motivated segmentation-guided registration method capable of handling large and smooth deformations. The shapes to be matched are viewed as hyperelastic materials and more precisely as Saint Venant–Kirchhoff ones and are implicitly modeled by level set functions. These are driven in order to minimize a functional containing both a nonlinear-elasticity-based regularizer prescribing the nature of the deformation, and a criterion that forces the evolving shape to match intermediate topology-preserving segmentation results. Theoretical results encompassing existence of minimizers, existence of a weak viscosity solution of the related evolution problem and asymptotic results are given. The study is then complemented by the derivation of the discrete counterparts of the asymptotic results provided in the continuous domain. Both a pure quadratic penalization method and an augmented Lagrangian technique (involving a related dual problem) are investigated with convergence results.  相似文献   
37.
The bread‐making potential of flour may be roughly estimated by dough rheology, especially its tolerance to over‐mixing as determined with the farinograph. The objective of this study was to identify the relative effects of experimental conditions likely to affect dough mixing stability: mixer speed, temperature, salt, yeast and bread additives such as ascorbic acid and preservatives. The addition of 1–2% salt or ascorbic acid (50 mg kg?1 flour) improved dough mixing stability and counteracted the negative effect of bread preservatives. Mixing salted dough at slow speed (63 rpm) and 25 °C might be a more realistic bread‐making procedure for performing dough rheology assays with equipment such as the farinograph, compared to official methods (only flour and water, no salt; 30 °C). Amongst five bread wheat cultivars, differences existed in dough strengthening response to both salt and ascorbic acid, a property that may find application in wheat breeding and screening.  相似文献   
38.
39.
This study evaluated in-car and in-bus exposures to methyl-tertiary butyl ether (MTBE), benzene, and toluene on actual commuting routes, not hypothetical routes as used in many previous in-vehicle exposure studies of volatile organic compounds (VOCs). It focuses on four potentially influencing factors (transportation mode, passenger-car type, time of day, and season). A total of 40 passenger car commuters and 20 public bus commuters were recruited. The same commuters participated in both the summer and winter studies. The transportation mode, passenger-car type and commute season were all found to affect the in-vehicle levels of the target VOCs. Conversely, the commute time of day had little effect on the in-car and in-bus levels of the target compounds. The present study also confirmed that under Korean commuting conditions, passenger car and public bus interiors are important microenvironments for exposure to MTBE, benzene and toluene. This is supported by a previous finding that both in-car and in-bus air levels of the target VOCs tend to be much higher than ambient air levels of the compounds. Meanwhile, some spurious gasoline sold during the experimental periods appears to have elevated the in-car and in-bus exposures to toluene compared with those reported by some previous studies conducted in the same study area.  相似文献   
40.
Learning domain ontologies for semantic Web service descriptions   总被引:1,自引:0,他引:1  
High quality domain ontologies are essential for successful employment of semantic Web services. However, their acquisition is difficult and costly, thus hampering the development of this field. In this paper we report on the first stage of research that aims to develop (semi-)automatic ontology learning tools in the context of Web services that can support domain experts in the ontology building task. The goal of this first stage was to get a better understanding of the problem at hand and to determine which techniques might be feasible to use. To this end, we developed a framework for (semi-)automatic ontology learning from textual sources attached to Web services. The framework exploits the fact that these sources are expressed in a specific sublanguage, making them amenable to automatic analysis. We implement two methods in this framework, which differ in the complexity of the employed linguistic analysis. We evaluate the methods in two different domains, verifying the quality of the extracted ontologies against high quality hand-built ontologies of these domains.

Our evaluation lead to a set of valuable conclusions on which further work can be based. First, it appears that our method, while tailored for the Web services context, might be applicable across different domains. Second, we concluded that deeper linguistic analysis is likely to lead to better results. Finally, the evaluation metrics indicate that good results can be achieved using only relatively simple, off the shelf techniques. Indeed, the novelty of our work is not in the used natural language processing methods but rather in the way they are put together in a generic framework specialized for the context of Web services.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号