全文获取类型
收费全文 | 657篇 |
免费 | 22篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 4篇 |
综合类 | 1篇 |
化学工业 | 138篇 |
金属工艺 | 24篇 |
机械仪表 | 16篇 |
建筑科学 | 21篇 |
能源动力 | 46篇 |
轻工业 | 51篇 |
水利工程 | 11篇 |
石油天然气 | 7篇 |
无线电 | 70篇 |
一般工业技术 | 162篇 |
冶金工业 | 56篇 |
原子能技术 | 11篇 |
自动化技术 | 63篇 |
出版年
2024年 | 3篇 |
2023年 | 6篇 |
2022年 | 14篇 |
2021年 | 23篇 |
2020年 | 20篇 |
2019年 | 14篇 |
2018年 | 23篇 |
2017年 | 20篇 |
2016年 | 27篇 |
2015年 | 22篇 |
2014年 | 23篇 |
2013年 | 40篇 |
2012年 | 38篇 |
2011年 | 48篇 |
2010年 | 37篇 |
2009年 | 24篇 |
2008年 | 41篇 |
2007年 | 30篇 |
2006年 | 23篇 |
2005年 | 14篇 |
2004年 | 13篇 |
2003年 | 13篇 |
2002年 | 13篇 |
2001年 | 11篇 |
2000年 | 9篇 |
1999年 | 7篇 |
1998年 | 14篇 |
1997年 | 6篇 |
1996年 | 16篇 |
1995年 | 9篇 |
1994年 | 5篇 |
1993年 | 10篇 |
1992年 | 6篇 |
1991年 | 7篇 |
1989年 | 7篇 |
1988年 | 4篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1985年 | 3篇 |
1984年 | 5篇 |
1983年 | 5篇 |
1982年 | 5篇 |
1981年 | 2篇 |
1978年 | 3篇 |
1977年 | 1篇 |
1976年 | 4篇 |
1975年 | 2篇 |
1972年 | 1篇 |
1966年 | 1篇 |
1965年 | 1篇 |
排序方式: 共有681条查询结果,搜索用时 31 毫秒
11.
Alok Singh Sitaram Dash Mohammed Kamruddin Puthupparampil K. Ajikumar Ashok K. Tyagi Vinjamoor S. Raghunathan Baldev Raj 《Journal of the American Ceramic Society》2002,85(4):927-932
Formation of nanocrystalline calcia from calcite has been studied in situ via transmission electron microscopy. The crystallographic transformation occurred via two mechanisms: the first is by distortion of the cleaved rhombohedron of calcite, formed by {104} planes in hexagonal coordinates, into a cube. This produced a microstructure of oriented, elongated nanocrystals of calcia with planar boundaries. In the second mechanism, the micrometer-sized parent calcite particles broke up into nano-sized grains as the decomposition began, leading to irregularly shaped, randomly oriented nanocrystals of calcia. 相似文献
12.
Jianyong Wang Yuzhou Zhang Lizhu Zhou George Karypis Charu C. Aggarwal 《Data mining and knowledge discovery》2009,18(1):1-29
In recent years we have witnessed several applications of frequent sequence mining, such as feature selection for protein
sequence classification and mining block correlations in storage systems. In typical applications such as clustering, it is
not the complete set but only a subset of discriminating frequent subsequences which is of interest. One approach to discovering
the subset of useful frequent subsequences is to apply any existing frequent sequence mining algorithm to find the complete
set of frequent subsequences. Then, a subset of interesting subsequences can be further identified. Unfortunately, it is very
time consuming to mine the complete set of frequent subsequences for large sequence databases. In this paper, we propose a
new algorithm, CONTOUR, which efficiently mines a subset of high-quality subsequences directly in order to cluster the input
sequences. We mainly focus on how to design some effective search space pruning methods to accelerate the mining process and
discuss how to construct an accurate clustering algorithm based on the result of CONTOUR. We conducted an extensive performance
study to evaluate the efficiency and scalability of CONTOUR, and the accuracy of the frequent subsequence-based clustering
algorithm. 相似文献
13.
14.
Wireless Personal Communications - Wireless Sensor Networks (WSNs) are used to collect and transmitted the data in various applications from normal to those which requires significant security... 相似文献
15.
Nitin Sharma Shanu Tyagi Satish Kumar Gupta Giriraj Thirupathirao Kulkarni Aseem Bhatnagar Neeraj Kumar 《Drug development and industrial pharmacy》2016,42(11):1763-1771
Objective: This work describes the application of natural plant polysaccharide as pharmaceutical mucoadhesive excipients in delivery systems to reduce the clearance rate through nasal cavity.Methods: Novel natural polysaccharide (Hibiscus rosasinensis)-based mucoadhesive microspheres were prepared by using emulsion crosslinking method for the delivery of rizatriptan benzoate (RB) through nasal route. Mucoadhesive microspheres were characterized for different parameters and nasal clearance of technetium-99m (99mTc)-radiolabeled microspheres was determined by using gamma-scintigraphy.Results: Their Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) studies showed that the drug was stable during preparation of microspheres. Aerodynamic diameter of microspheres was in the range 13.23?±?1.83–33.57?±?3.69?µm. Change in drug and polysaccharide ratio influenced the mucoadhesion, encapsulation efficiency and in-vitro release property. Scintigraphs taken at regular interval indicate that control solution was cleared rapidly from nasal cavity, whereas microspheres showed slower clearance (p?0.005) with half-life of 160?min.Conclusion: Natural polysaccharide-based microspheres achieved extended residence by minimizing effect of mucociliary clearance with opportunity of sustained delivery for longer duration. 相似文献
16.
Facility location decisions are usually determined by cost and coverage related factors although empirical studies show that such factors as infrastructure, labor conditions and competition also play an important role in practice. The objective of this paper is to develop a multi-objective facility location model accounting for a wide range of factors affecting decision-making. The proposed model selects potential facilities from a set of pre-defined alternative locations according to the number of customers, the number of competitors and real-estate cost criteria. However, that requires large amount of both spatial and non-spatial input data, which could be acquired from distributed data sources over the Internet. Therefore, a computational approach for processing input data and representation of modeling results is elaborated. It is capable of accessing and processing data from heterogeneous spatial and non-spatial data sources. Application of the elaborated data gathering approach and facility location model is demonstrated using an example of fast food restaurants location problem. 相似文献
17.
Qi GJ Aggarwal C Tian Q Ji H Huang TS 《IEEE transactions on pattern analysis and machine intelligence》2012,34(5):850-862
Social media networks contain both content and context-specific information. Most existing methods work with either of the two for the purpose of multimedia mining and retrieval. In reality, both content and context information are rich sources of information for mining, and the full power of mining and processing algorithms can be realized only with the use of a combination of the two. This paper proposes a new algorithm which mines both context and content links in social media networks to discover the underlying latent semantic space. This mapping of the multimedia objects into latent feature vectors enables the use of any off-the-shelf multimedia retrieval algorithms. Compared to the state-of-the-art latent methods in multimedia analysis, this algorithm effectively solves the problem of sparse context links by mining the geometric structure underlying the content links between multimedia objects. Specifically for multimedia annotation, we show that an effective algorithm can be developed to directly construct annotation models by simultaneously leveraging both context and content information based on latent structure between correlated semantic concepts. We conduct experiments on the Flickr data set, which contains user tags linked with images. We illustrate the advantages of our approach over the state-of-the-art multimedia retrieval techniques. 相似文献
18.
Friction and scuffing behaviour of grey cast iron as influenced by the surface roughness under sparse lubrication conditions is studied. The studies are carried out on a three-shoe-on-disc machine under the conditions of parallel sliding. The experiments were conducted at three oil supply rates of 0.10, 0.22 and 0.36 μg/cm2 per contact obtained through a mist oiling system and with specimens of cast iron shoes of different roughness values, Ra, between 0.04 and 2.0 μm against a 0.55% C steel disc. In a step load procedure, the friction torque at the end of each load step and the scuffing load are the major parameters measured. Results of friction and scuffing behaviour as a function of roughness and oil supply rates have been discussed. 相似文献
19.
R. K. Tyagi K. K. Srivastava R. S. Pandey 《Surface Engineering and Applied Electrochemistry》2012,48(1):64-68
The material removal within different machining process can be performed in distinct modalities. One of the modality is based
on the effect of impact phenomenon. In this paper theoretical model of non-traditional machining process based on impact phenomenon
is discussed. The material is removed from the surface due to the impact of ions. The velocity of ions is equal to the velocity
at which the electrostatic ion-cyclotron instability driven by parallel flow velocity shear generated by massive ions takes
place. The main ways for the material removal as consequence of the impact phenomenon are the microcracking, microcutting,
melting and vaporizing of small quantities from the work-piece surface layer. 相似文献
20.
Anshu Tyagi Florian Döring Hans-Ulrich Krebs Astrid Pundt 《International Journal of Hydrogen Energy》2017,42(35):22575-22582
The influence of a thin polycarbonate de-adhesion layer on the hydrogen concentration is studied on 30 nm vanadium films deposited on glass substrates, using electrochemical hydrogenography in an optical microscopy and scanning tunneling microscopy. It is shown that the optical reflection provides information about the de-adhesion morphology (buckles) while the optical transmission signal gives information about concentration and film thickness changes. Artificially patterned samples allow simultaneous studying adhered and de-adhered film parts, for similar mean concentrations. The optical data clearly show a different hydrogen behavior of the two parts. Data interpretation suggests higher local hydrogen content in the adhered film parts than for the detached films parts. Strong changes in the optical transmission of the adhered film parts can be attributed to strong morphological changes at the film surface. These changes are mainly attributed to grain sliding processes in the vanadium film. 相似文献