全文获取类型
收费全文 | 13407篇 |
免费 | 1132篇 |
国内免费 | 9篇 |
专业分类
电工技术 | 77篇 |
综合类 | 10篇 |
化学工业 | 5417篇 |
金属工艺 | 133篇 |
机械仪表 | 325篇 |
建筑科学 | 479篇 |
矿业工程 | 18篇 |
能源动力 | 347篇 |
轻工业 | 3431篇 |
水利工程 | 120篇 |
石油天然气 | 77篇 |
无线电 | 486篇 |
一般工业技术 | 1781篇 |
冶金工业 | 552篇 |
原子能技术 | 36篇 |
自动化技术 | 1259篇 |
出版年
2024年 | 45篇 |
2023年 | 205篇 |
2022年 | 965篇 |
2021年 | 1102篇 |
2020年 | 453篇 |
2019年 | 477篇 |
2018年 | 527篇 |
2017年 | 552篇 |
2016年 | 583篇 |
2015年 | 474篇 |
2014年 | 634篇 |
2013年 | 919篇 |
2012年 | 891篇 |
2011年 | 1010篇 |
2010年 | 767篇 |
2009年 | 703篇 |
2008年 | 637篇 |
2007年 | 604篇 |
2006年 | 461篇 |
2005年 | 341篇 |
2004年 | 293篇 |
2003年 | 264篇 |
2002年 | 241篇 |
2001年 | 145篇 |
2000年 | 96篇 |
1999年 | 131篇 |
1998年 | 108篇 |
1997年 | 109篇 |
1996年 | 101篇 |
1995年 | 70篇 |
1994年 | 58篇 |
1993年 | 58篇 |
1992年 | 64篇 |
1991年 | 46篇 |
1990年 | 39篇 |
1989年 | 33篇 |
1988年 | 33篇 |
1987年 | 31篇 |
1986年 | 41篇 |
1985年 | 35篇 |
1984年 | 26篇 |
1983年 | 22篇 |
1982年 | 15篇 |
1981年 | 16篇 |
1980年 | 19篇 |
1979年 | 19篇 |
1978年 | 20篇 |
1977年 | 13篇 |
1976年 | 7篇 |
1975年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
141.
142.
Ilaria Bartolini Vincenzo Moscato Ruggero G. Pensa Antonio Penta Antonio Picariello Carlo Sansone Maria Luisa Sapino 《Multimedia Tools and Applications》2016,75(7):3813-3842
The valorization and promotion of worldwide Cultural Heritage by the adoption of Information and Communication Technologies represent nowadays some of the most important research issues with a large variety of potential applications. This challenge is particularly perceived in the Italian scenario, where the artistic patrimony is one of the most diverse and rich of the world, able to attract millions of visitors every year to monuments, archaeological sites and museums. In this paper, we present a general recommendation framework able to uniformly manage heterogeneous multimedia data coming from several web repositories and to provide context-aware recommendation techniques supporting intelligent multimedia services for the users—i.e. dynamic visiting paths for a given environment. Specific applications of our system within the cultural heritage domain are proposed by means of real case studies in the mobile environment related both to an outdoor and indoor scenario, together with some results on user’s satisfaction and system accuracy. 相似文献
143.
Maxim Shishmarev Christopher Mears Guido Tack Maria Garcia de la Banda 《Constraints》2016,21(1):77-94
Understanding how the search space is explored for a given constraint problem – and how it changes for different models, solvers or search strategies – is crucial for efficient solving. Yet programmers often have to rely on the crude aggregate measures of the search that are provided by solvers, or on visualisation tools that can show the search tree, but do not offer sophisticated ways to navigate and analyse it, particularly for large trees. We present an architecture for profiling a constraint programming search that is based on a lightweight instrumentation of the solver. The architecture combines a visualisation of the search tree with various tools for convenient navigation and analysis of the search. These include identifying repeated subtrees, high-level abstraction and navigation of the tree, and the comparison of two search trees. The resulting system is akin to a traditional program profiler, which helps the user to focus on the parts of the execution where an improvement to their program would have the greatest effect. 相似文献
144.
Azadeh?Jahanbanifar Ferhat?KhendekEmail author Maria?Toeroe 《Information Systems Frontiers》2016,18(5):891-908
Configuration fragments developed separately and focusing on different aspects, such as availability, security or performance of a system need to be integrated into a consistent system configuration to avoid system malfunctions. The main challenges of such integration are due to the overlapping entities and the integration relations between the entities of the different configuration fragments. In this paper we propose a model based approach for a consistent integration of configuration fragments into a system configuration. We use and extend the model weaving technique to capture the semantics of the relations between the entities of the configuration fragments. Moreover, we generate automatically the constraints corresponding to these semantic relations to complete the target system configuration profile. These constraints can be used to guard the configuration consistency during runtime modifications. 相似文献
145.
146.
147.
Andre Suslik Spritzer Jeremy Boy Pierre Dragicevic Jean‐Daniel Fekete Carla Maria Dal Sasso Freitas 《Computer Graphics Forum》2015,34(3):461-470
Node‐link infographics are visually very rich and can communicate messages effectively, but can be very difficult to create, often involving a painstaking and artisanal process. In this paper we present an investigation of node‐link visualizations for communication and how to better support their creation. We begin by breaking down these images into their basic elements and analyzing how they are created. We then present a set of techniques aimed at improving the creation workflow by bringing more flexibility and power to users, letting them manipulate all aspects of a node‐link diagram (layout, visual attributes, etc.) while taking into account the context in which it will appear. These techniques were implemented in a proof‐of‐concept prototype called GraphCoiffure, which was designed as an intermediary step between graph drawing/editing software and image authoring applications. We describe how GraphCoiffure improves the workflow and illustrate its benefits through practical examples. 相似文献
148.
Agnieszka Latosinska Maria Frantzi Antonia Vlahou Harald Mischak 《Proteomics. Clinical applications》2013,7(11-12):779-793
A major requirement in the application of proteins as clinical biomarkers is that they provide a highly sensitive and specific result in disease assessment. Since single biomarkers are generally of limited accuracy, a group or panel of well-characterized biomarkers appears appropriate, providing a more robust and sensitive MS-based analytical platform. CE coupled to MS has been successfully used in biomarker discovery and application, as it enables the selective detection of peptides and small proteins, combining the high separation capacity of CE with the advanced sensitivity of MS. CE-MS allows the characterization of highly complex samples (such as urine, plasma, and other biofluids) in a consistent and reproducible way. It has a range of applications, many focusing especially in studies on urinary peptide biomarkers in kidney and cardiovascular diseases. Another major field of interest has been malignancy of the genitourinary system. In the first part of this review, we cover technical aspects and performance characteristics of CE-MS, with special focus on the requirements for biomarker discovery and clinical application. In the second part, we review the potential and development of CE-MS in the management of genitourinary cancers, especially bladder cancer. CE-MS has been employed in several studies aimed at discovering biomarkers for bladder cancer that may be useful in diagnosis, monitoring for recurrence, and prediction of the risk for the muscle-invasive stage. In the last part of the review, we discuss current challenges and provide an outlook for ongoing and possible future developments. 相似文献
149.
Georg Gottlob Thomas Lukasiewicz Maria Vanina Martinez Gerardo I. Simari 《Annals of Mathematics and Artificial Intelligence》2013,69(1):37-72
The recently introduced Datalog+?/?? family of ontology languages is especially useful for representing and reasoning over lightweight ontologies, and is set to play a central role in the context of query answering and information extraction for the Semantic Web. Recently, it has become apparent that it is necessary to develop a principled way to handle uncertainty in this domain. In addition to uncertainty as an inherent aspect of the Web, one must also deal with forms of uncertainty due to inconsistency and incompleteness, uncertainty resulting from automatically processing Web data, as well as uncertainty stemming from the integration of multiple heterogeneous data sources. In this paper, we take an important step in this direction by developing a probabilistic extension of Datalog+?/??. This extension uses Markov logic networks as the underlying probabilistic semantics. Here, we focus especially on scalable algorithms for answering threshold queries, which correspond to the question “what is the set of all ground atoms that are inferred from a given probabilistic ontology with a probability of at least p?”. These queries are especially relevant to Web information extraction, since uncertain rules lead to uncertain facts, and only information with a certain minimum confidence is desired. We present several algorithms, namely a basic approach, an anytime one, and one based on heuristics, which is guaranteed to return sound results. Furthermore, we also study inconsistency in probabilistic Datalog+?/?? ontologies. We propose two approaches for computing preferred repairs based on two different notions of distance between repairs, namely symmetric and score-based distance. We also study the complexity of the decision problems corresponding to computing such repairs, which turn out to be polynomial and NP-complete in the data complexity, respectively. 相似文献
150.
Ants present a pair of metapleural glands located at the posterolateral end of the thorax. Because of its importance in the social organization of ants, the present study was aimed at describing the morphophysiology of this gland in three worker castes of Acromyrmex coronatus, focused on secretory activity using histological and histochemical techniques. Our findings revealed that the secretory and the storage portions of this gland are connected by extracytoplasmic portion of canaliculi that drain the secretion from each secretory cell to the collecting chamber. This secretion contains glycoproteins. In minor workers, the secretion contains higher levels of polysaccharides when compared to that of major workers, supporting the role of the metapleural gland in the maintenance of the fungus garden. The nucleus as well as cytoplasm of secretory cells were strongly positive for RNA indicating that these cells are active in the synthesis of proteins and lipids, compounds found in the final secretion. The variant of the CEC revealed that the secretory activity of the entire gland is synchronous, as all cells exhibit the result. 相似文献