全文获取类型
收费全文 | 1320篇 |
免费 | 51篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 10篇 |
化学工业 | 277篇 |
金属工艺 | 55篇 |
机械仪表 | 35篇 |
建筑科学 | 108篇 |
矿业工程 | 2篇 |
能源动力 | 65篇 |
轻工业 | 194篇 |
水利工程 | 4篇 |
石油天然气 | 4篇 |
无线电 | 60篇 |
一般工业技术 | 273篇 |
冶金工业 | 59篇 |
原子能技术 | 20篇 |
自动化技术 | 207篇 |
出版年
2023年 | 5篇 |
2022年 | 16篇 |
2021年 | 26篇 |
2020年 | 14篇 |
2019年 | 16篇 |
2018年 | 17篇 |
2017年 | 32篇 |
2016年 | 28篇 |
2015年 | 27篇 |
2014年 | 38篇 |
2013年 | 79篇 |
2012年 | 58篇 |
2011年 | 99篇 |
2010年 | 61篇 |
2009年 | 78篇 |
2008年 | 88篇 |
2007年 | 82篇 |
2006年 | 58篇 |
2005年 | 53篇 |
2004年 | 51篇 |
2003年 | 44篇 |
2002年 | 45篇 |
2001年 | 26篇 |
2000年 | 20篇 |
1999年 | 14篇 |
1998年 | 30篇 |
1997年 | 24篇 |
1996年 | 18篇 |
1995年 | 15篇 |
1994年 | 11篇 |
1993年 | 13篇 |
1992年 | 9篇 |
1991年 | 11篇 |
1990年 | 13篇 |
1989年 | 12篇 |
1988年 | 15篇 |
1987年 | 13篇 |
1986年 | 13篇 |
1985年 | 11篇 |
1984年 | 10篇 |
1983年 | 12篇 |
1982年 | 7篇 |
1981年 | 7篇 |
1980年 | 8篇 |
1979年 | 8篇 |
1978年 | 7篇 |
1976年 | 7篇 |
1974年 | 7篇 |
1973年 | 3篇 |
1972年 | 4篇 |
排序方式: 共有1373条查询结果,搜索用时 15 毫秒
41.
Martti Heinonen Miltiadis Anagnostou Stephanie Bell Mark Stevens Robert Benyon Reidun Anita Bergerud Jovan Bojkovski Rien Bosma Jan Nielsen Norbert B?se Plunkett Cromwell Aliye Kartal Dogan Seda Aytekin Ali Uytun Vito Fernicola Krzysztof Flakiewicz Bertrand Blanquart Domen Hudoklin Per Jacobson Anders Kentved Isabel Lóio George Mamontov Alexandra Masarykova Helmut Mitter Regina Mnguni Jan Otych Anton Steiner Nagyné Szilágyi Zsófia Davor Zvizdic 《International Journal of Thermophysics》2012,33(8-9):1422-1437
In the field of humidity quantities, the first CIPM key comparison, CCT-K6 is at its end. The corresponding European regional key comparison, EUROMET.T-K6, was completed in early 2008, about 4?years after the starting initial measurements in the project. In total, 24 NMIs from different countries took part in the comparison. This number includes 22 EURAMET countries, and Russia and South Africa. The comparison covered the dew-point temperature range from ?50?°C to +20?°C. It was carried out in three parallel loops, each with two chilled mirror hygrometers as transfer standards in each loop. The comparison scheme was designed to ensure high quality results with evenly spread workload for the participants. It is shown that the standard uncertainty due to the long-term instability was smaller than 0.008?°C in all loops. The standard uncertainties due to links between the loops were found to be smaller than 0.025?°C at ?50?°C and 0.010?°C elsewhere. Conclusions on the equivalence of the dew-point temperature standards are drawn on the basis of calculated bilateral degrees of equivalence and deviations from the EURAMET comparison reference values (ERV). Taking into account 16 different primary dew-point realizations and 8 secondary realizations, the results demonstrate the equivalence of a large number of laboratories at an uncertainty level that is better than achieved in other multilateral comparisons so far in the humidity field. 相似文献
42.
We compared three different bibliometric evaluation approaches: two citation-based approaches and one based on manual classification of publishing channels into quality levels. Publication data for two universities was used, and we worked with two levels of analysis: article and department. For the article level, we investigated the predictive power of field normalized citation rates and field normalized journal impact with respect to journal level. The results for the article level show that evaluation of journals based on citation impact correlate rather well with manual classification of journals into quality levels. However, the prediction from field normalized citation rates to journal level was only marginally better than random guessing. At the department level, we studied three different indicators in the context of research fund allocation within universities and the extent to which the three indicators produce different distributions of research funds. It turned out that the three distributions of relative indicator values were very similar, which in turn yields that the corresponding distributions of hypothetical research funds would be very similar. 相似文献
43.
Konovalenko Alexander Sköld Per Kudinov Pavel Bechta Sevostian Grishchenko Dmitry 《Metallurgical and Materials Transactions B》2017,48(2):1064-1072
Metallurgical and Materials Transactions B - We develop a method for generation of a single gas bubble in a pool of molten metal. The method can be useful for applications and research studies... 相似文献
44.
In this article, an extended version of the unified theory of acceptance and use of technology (UTAUT) is applied to explore the significance of various antecedents of acceptance of eight versions of a radio frequency identification (RFID) enabled service. The results show significant influences from performance expectancy, effort expectancy and technology anxiety on attitude to use RFID-enabled services, while facilitating conditions and attitude to use both have significant influences on intention to use the services. Looking into potential moderating influences, gender moderates most of the relationships in the model while age and experience with identification technology do not seem to be relevant moderators. Exploring the potential moderating influence of context experience, experience of the service context is found to moderate some of the relationships in the model. Managerial implications point to the importance of developing useful and user-friendly services and of communicating the user friendliness to potential customers to avoid the potential negative influence of technology anxiety. Service development and market communication should be sensitive to gender and context experience. 相似文献
45.
Livia Pagano Angelo Toto Francesca Malagrin Lorenzo Visconti Per Jemth Stefano Gianni 《International journal of molecular sciences》2021,22(2)
Quantitative measurement of intramolecular and intermolecular interactions in protein structure is an elusive task, not easy to address experimentally. The phenomenon denoted ‘energetic coupling’ describes short- and long-range interactions between two residues in a protein system. A powerful method to identify and quantitatively characterize long-range interactions and allosteric networks in proteins or protein–ligand complexes is called double-mutant cycles analysis. In this review we describe the thermodynamic principles and basic equations that underlie the double mutant cycle methodology, its fields of application and latest employments, and caveats and pitfalls that the experimentalists must consider. In particular, we show how double mutant cycles can be a powerful tool to investigate allosteric mechanisms in protein binding reactions as well as elusive states in protein folding pathways. 相似文献
46.
Scientometrics - Journal rankings often show significant changes compared to previous rankings. This gives rise to the question of how well estimated the rank of a journal is. In this contribution,... 相似文献
47.
48.
Tero Luukkonen Emma-Tuulia Tolonen Hanna Runtti Kimmo Kemppainen Paavo Perämäki Jaakko Rämö Ulla Lassi 《Journal of Materials Science》2017,52(16):9363-9376
Geopolymers are functional materials that can be used in various environmental applications such as adsorbents in pollutant removal from wastewaters. Metakaolin geopolymer (MK-GP) has been proven to be especially suitable for ammonium (NH4 +) removal. In this research, the optimal reagent and raw material ratios in the preparation of MK-GP in terms of NH4 + adsorption capacity were investigated. The response surface methodology based on the face-centered central composite design was used to optimize the levels of three factors: the amounts of hydroxide, silicate, and metakaolin. In addition, the effect of Na or K as the charge-balancing cation was studied. Empirical models were fitted to the experimental data using multiple linear regression. The significance of the models was confirmed by means of analysis of variance. Optimal NH4 + removal efficiency was achieved when the amounts of hydroxide and silicate were maximized, the amount of metakaolin was minimized, and Na-based reagents were used. These trends are most likely a result of optimized conversion of metakaolin into MK-GP. 相似文献
49.
Per Kreuger Rebecca Steinert Olof Görnerup Daniel Gillblad 《International Journal of Network Management》2018,28(2)
Managing and balancing load in distributed systems remains a challenging problem in resource management, especially in networked systems where scalability concerns favour distributed and dynamic approaches. Distributed methods can also integrate well with centralised control paradigms if they provide high‐level usage statistics and control interfaces for supporting and deploying centralised policy decisions. We present a general method to compute target values for an arbitrary metric on the local system state and show that autonomous rebalancing actions based on the target values can be used to reliably and robustly improve the balance for metrics based on probabilistic risk estimates. To balance the trade‐off between balancing efficiency and cost, we introduce 2 methods of deriving rebalancing actuations from the computed targets that depend on parameters that directly affects the trade‐off. This enables policy level control of the distributed mechanism based on collected metric statistics from network elements. Evaluation results based on cellular radio access network simulations indicate that load balancing based on probabilistic overload risk metrics provides more robust balancing solutions with fewer handovers compared to a baseline setting based on average load. 相似文献
50.
This paper analyzes the sources of performance losses in hardware transactional memory and investigates techniques to reduce the losses. It dissects the root causes of data conflicts in hardware transactional memory systems (HTM) into four classes of conflicts: true sharing, false sharing, silent store, and write-write conflicts. These conflicts can cause performance and energy losses due to aborts and extra communication. To quantify losses, the paper proposes the 5C cache-miss classification model that extends the well-established 4C model with a new class of cache misses known as contamination misses. The paper also contributes with two techniques for removal of data conflicts: One for removal of false sharing conflicts and another for removal of silent store conflicts. In addition, it revisits and adapts a technique that is able to reduce losses due to both true and false conflicts. All of the proposed techniques can be accommodated in a lazy versioning and lazy conflict resolution HTM built on top of a MESI cache-coherence infrastructure with quite modest extensions. Their ability to reduce performance is quantitatively established, individually as well as in combination. Performance and energy consumption are improved substantially. 相似文献