全文获取类型
收费全文 | 7012篇 |
免费 | 414篇 |
国内免费 | 16篇 |
学科分类
工业技术 | 7442篇 |
出版年
2023年 | 75篇 |
2022年 | 67篇 |
2021年 | 260篇 |
2020年 | 167篇 |
2019年 | 152篇 |
2018年 | 243篇 |
2017年 | 217篇 |
2016年 | 237篇 |
2015年 | 202篇 |
2014年 | 303篇 |
2013年 | 479篇 |
2012年 | 442篇 |
2011年 | 557篇 |
2010年 | 400篇 |
2009年 | 392篇 |
2008年 | 380篇 |
2007年 | 369篇 |
2006年 | 249篇 |
2005年 | 204篇 |
2004年 | 198篇 |
2003年 | 182篇 |
2002年 | 161篇 |
2001年 | 86篇 |
2000年 | 91篇 |
1999年 | 97篇 |
1998年 | 183篇 |
1997年 | 149篇 |
1996年 | 88篇 |
1995年 | 62篇 |
1994年 | 59篇 |
1993年 | 53篇 |
1992年 | 49篇 |
1991年 | 36篇 |
1990年 | 42篇 |
1989年 | 36篇 |
1988年 | 33篇 |
1987年 | 24篇 |
1986年 | 35篇 |
1985年 | 38篇 |
1984年 | 25篇 |
1983年 | 25篇 |
1982年 | 21篇 |
1981年 | 20篇 |
1980年 | 28篇 |
1979年 | 22篇 |
1977年 | 21篇 |
1976年 | 42篇 |
1975年 | 12篇 |
1974年 | 20篇 |
1973年 | 15篇 |
排序方式: 共有7442条查询结果,搜索用时 15 毫秒
91.
Adam Jacobson Fan Zeng David Smith Nigel Boswell Thierry Peynot Michael Milford 《野外机器人技术杂志》2021,38(1):5-27
Robustly and accurately localizing vehicles in underground mines is particularly challenging due to the unavailability of GPS, variable and often poor lighting conditions, visual aliasing in long tunnels, and airborne dust and water. In this paper, we present a novel, infrastructure‐less, multisensor localization method for robust autonomous operation within underground mines. The proposed method integrates with existing mine site commissioning and operation procedures and includes both an offline map‐building process and an online localization algorithm. The approach combines the strengths of visual‐based place recognition, LIDAR‐based localization, and odometry in a particle filter fusion process. We provide an extensive experimental validation using new large data sets acquired in two operational Australian underground hard‐rock mines (including a 600m‐deep multilevel mine with approximately 33 km of mapping data and 7 km of vehicle localization) by actual mining vehicles during production operations. We demonstrate a significant increase in localization accuracy over prior state‐of‐the‐art SLAM research systems and real‐time operation, with processing times in the order of 10 Hz. We present results showing a mean error of 0.68 m from the Queensland Mine data set and 1.32 m from the New South Wales Mine data set and at least 86% reduction in error compared with prior state of the art. We also analyze the impact of the particle filter parameters with respect to localization accuracy. Together this study represents a new approach to positioning systems for currently deployed autonomous vehicles within underground mine environments. 相似文献
92.
Manibarathi Vaithiyanathan Hannah C. Hymel Nora Safa Olivia M. Sanchez Jacob H. Pettigrew Cole S. Kirkpatrick Ted J. Gauthier Adam T. Melvin 《American Institute of Chemical Engineers》2021,67(1):e17087
Most cell penetrating peptides (CPPs) are unstructured and susceptible to proteolytic degradation. One alternative is to incorporate D-chirality amino acids into unstructured CPPs to allow for enhanced uptake and intracellular stability. This work investigates CPP internalization using a series of time, concentration, temperature, and energy dependent studies, resulting in a three-fold increase in uptake and 50-fold increase in stability of D-chirality peptides over L-chirality counterparts. CPP internalization occurred via a combination of direct penetration and endocytosis, with a percentage of internalized CPP expelling from cells in a time-dependent manner. Mechanistic studies identified that cells exported the intact internalized D-chirality CPPs via an exocytosis independent pathway, analogous to a direct penetration method out of the cells. These findings highlight the potential of a D-chirality CPP as bio-vector in therapeutic and biosensing applications, but also identify a new expulsion method suggesting a relationship between uptake kinetics, intracellular stability, and export kinetics. 相似文献
93.
Ioannis Bagkeris Vipin Michael Robert Prosser Adam Kowalski 《American Institute of Chemical Engineers》2021,67(7):e17201
The assumption of homogeneous isotropic turbulence when modeling drop breakage in industrially relevant geometries is questionable. We describe the development of an anisotropic breakage model, where the anisotropy is introduced via the inclusion of a perturbed turbulence spectrum. The selection of the perturbed spectrum is itself motivated by our previous large-eddy simulations of high-pressure homogenizers. The model redistributes energy from small to large scales, and assumes that the anisotropic part of the Reynolds stresses is confined to the energy-containing range. The second-order structure function arising from the perturbed spectrum is used in the standard framework of Coulaloglou and Tavlarides to calculate breakage frequency. While the base model exhibits non-monotonic behavior (by predicting a maximum value for a certain drop size), the effect of anisotropy is shown to increase breakage frequency in length scales larger than this peak, thereby reducing non-monotonicity. This effect is more pronounced for small turbulence Reynolds numbers. 相似文献
94.
Nataraj Nandita Adam Elisabeth Hansson Bill S. Knaden Markus 《Journal of chemical ecology》2021,47(12):1042-1048
Journal of Chemical Ecology - Many pollinating insects exhibit flower constancy, i.e. they target flower species they have already experienced and fed from. While the insects might profit from... 相似文献
95.
D. L. Zhang Z. H. Cai G. Adam 《JOM Journal of the Minerals, Metals and Materials Society》2004,56(2):53-56
The processing of Al/TiO2 composite powders produced by high-energy mechanical milling leads to production of a range of valuable, titanium-based materials.
They include Ti(Al,O)/Al2O3 and TixAly(O)/Al2O3 composite powders, bulk composites and Ti3Al/TiAl alloy powders, and corresponding bulk materials. The strength of the Ti(Al,O)/Al2O3 and TixAly(O)/Al2O3 composites is moderate, but their high-temperature oxidation resistance is exceptionally high, making the titanium-based
composite powders favorable feedstock materials for protective coatings. The hardness of the Ti(Al,O)/Al2O3 and Ti3Al(O)/Al2O3 composites is also very high (10–16 GPa).
For more information, contact D.L. Zhang, University of Waikato, Waikato Centre for Advanced Materials, Department of Materials
and Process Engineering, Private Bag 3105, Hamilton, New Zealand; 011-64-7-838-4783; fax 011-64-7-838-4835; e-mail d.zhang@waikato.ac.nz. 相似文献
96.
In this paper, basic relationships and algorithms for numerical simulation of non-linear, self-excited vibrations in single degree-of-freedom cutting systems are presented. Non-linearities due to the tool leaving the cut, as well as interference between the cutting tool clearance face and cutting surface waviness, were taken into consideration. Examples of vibration simulation results are shown. 相似文献
97.
In this article I argue for rule-based, non-monotonic theories of common law judicial reasoning and improve upon one such theory offered by Horty and Bench-Capon. The improvements reveal some of the interconnections between formal theories of judicial reasoning and traditional issues within jurisprudence regarding the notions of the ratio decidendi and obiter dicta. Though I do not purport to resolve the long-standing jurisprudential issues here, it is beneficial for theorists both of legal philosophy and formalizing legal reasoning to see where the two projects interact. 相似文献
98.
Vincent C. Müller 《人工智能实验与理论杂志》2015,27(1):73-78
Floridi and Taddeo propose a condition of ‘zero semantic commitment’ for solutions to the grounding problem, and a solution to it. I argue briefly that their condition cannot be fulfilled, not even by their own solution. After a look at Luc Steel's very different competing suggestion, I suggest that we need to re-think what the problem is and what role the ‘goals’ in a system play in formulating the problem. On the basis of a proper (syntactic) understanding of computing, I come to the conclusion that the only sensible grounding problem is how we can explain and re-produce the behavioural ability and function of meaning in artificial computational agents. 相似文献
99.
Anuja Hariharan Marc Thomas Philipp Adam Timm Teubner Christof Weinhardt 《Electronic Markets》2016,26(4):339-355
Environmental conditions and the interplay of cognitive and affective processes both exert influences on bidding behavior. This paper brings the above together, considering how the (external) auction environment determines the impact of (internal) cognitive and affective processes on bidding behavior, assessed in comparison to the optimal bid. Two aspects of the auction environment were considered, namely auction dynamics (low: first-price sealed-bid auction, high: Dutch auction) and value uncertainty (low, high). In a laboratory experiment, we assess bidders’ cognitive workload and emotional arousal through physiological measurements. We find that higher auction dynamics increase the impact of emotional arousal on bid deviations, but not that of cognitive workload. Higher value uncertainty, conversely, increases the impact of cognitive workload on bid deviations, but not that of emotional arousal. Taken together, the auction environment is a critical factor in understanding the nature of the underlying decision process and its impact on bids. 相似文献
100.
Kaouthar?DeghdakEmail authorView authors OrcID profile Vincent?T’kindt Jean-Louis?Bouquard 《Journal of Scheduling》2016,19(4):467-478
In this paper, we consider a large-scale evacuation problem after a major disaster. The evacuation is assumed to occur by means of a fleet of buses, thus leading to scheduling the evacuation operations by buses [(bus evacuation problem (BEP)]. We propose time-indexed formulations as well as heuristic algorithms such as greedy algorithms and a matheuristic. This matheuristic uses the former formulation to improve the best solution obtained by the greedy heuristics. In computational experiments, we analyze and evaluate the efficiency of the proposed solution algorithms. 相似文献