全文获取类型
收费全文 | 2609篇 |
免费 | 171篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 13篇 |
综合类 | 4篇 |
化学工业 | 780篇 |
金属工艺 | 7篇 |
机械仪表 | 40篇 |
建筑科学 | 97篇 |
矿业工程 | 1篇 |
能源动力 | 46篇 |
轻工业 | 533篇 |
水利工程 | 22篇 |
石油天然气 | 13篇 |
无线电 | 97篇 |
一般工业技术 | 292篇 |
冶金工业 | 593篇 |
原子能技术 | 12篇 |
自动化技术 | 232篇 |
出版年
2024年 | 12篇 |
2023年 | 31篇 |
2022年 | 128篇 |
2021年 | 143篇 |
2020年 | 54篇 |
2019年 | 65篇 |
2018年 | 103篇 |
2017年 | 94篇 |
2016年 | 109篇 |
2015年 | 73篇 |
2014年 | 111篇 |
2013年 | 165篇 |
2012年 | 139篇 |
2011年 | 167篇 |
2010年 | 125篇 |
2009年 | 121篇 |
2008年 | 118篇 |
2007年 | 102篇 |
2006年 | 95篇 |
2005年 | 87篇 |
2004年 | 65篇 |
2003年 | 57篇 |
2002年 | 56篇 |
2001年 | 31篇 |
2000年 | 35篇 |
1999年 | 28篇 |
1998年 | 32篇 |
1997年 | 32篇 |
1996年 | 35篇 |
1995年 | 23篇 |
1994年 | 29篇 |
1993年 | 22篇 |
1992年 | 34篇 |
1990年 | 23篇 |
1989年 | 22篇 |
1988年 | 17篇 |
1987年 | 22篇 |
1986年 | 16篇 |
1985年 | 15篇 |
1984年 | 22篇 |
1982年 | 8篇 |
1981年 | 23篇 |
1980年 | 7篇 |
1979年 | 15篇 |
1978年 | 10篇 |
1977年 | 12篇 |
1976年 | 7篇 |
1975年 | 7篇 |
1974年 | 6篇 |
1972年 | 6篇 |
排序方式: 共有2782条查询结果,搜索用时 0 毫秒
41.
Sandra García‐Bustos Mónica Mite Francisco Vera 《Quality and Reliability Engineering International》2016,32(5):1741-1755
This article analyzes the simultaneous control of several correlated Poisson variables by using the Variable Dimension Linear Combination of Poisson Variables (VDLCP) control chart, which is a variable dimension version of the LCP chart. This control chart uses as test statistic, the linear combination of correlated Poisson variables in an adaptive way, i.e. it monitors either p1 or p variables (p1 < p) depending on the last statistic value. To analyze the performance of this chart, we have developed software that finds the best parameters, optimizing the out‐of‐control average run length (ARL) for a shift that the practitioner wishes to detect as quickly as possible, restricted to a fixed value for in‐control ARL. Markov chains and genetic algorithms were used in developing this software. The results show performance improvement compared to the LCP chart. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
42.
Sandra Križić Roban 《Photographies》2018,11(2-3):215-234
Post-war experimental and conceptual photography in former Yugoslavia has only rarely been the subject of detailed study and interpretation. In considering this period, it is necessary to take into account several factors, including the absence of permanent exhibition spaces for photography, the lack of magazines in which photographic themes were presented and discussed, the impossibility of studying the field of photography and, finally, the inadequate knowledge and application of contemporary criticism and theories of photography. Nevertheless, from the mid-1950s onwards it is possible to note a variety of innovations in the field, in terms of both form and subject-matter. This article considers rare instances of institutional support for progressive photography-related events and unique, intellectual-poetic works. After the break-up of Yugoslavia, there is a dominant tendency to nationalize art created in the former state, thus ignoring the specific Yugoslav cultural field as well as the European context. Based on a methodology which surpasses the national (but still acknowledges it) and searches for meaning within the broader socio-political space to which art is referring, the research aims to change the paradigm of the peripheral position and general ignorance of the circumstances under which this innovative practice emerges. 相似文献
43.
44.
Most work on pattern mining focuses on simple data structures such as itemsets and sequences of itemsets. However, a lot of recent applications dealing with complex data like chemical compounds, protein structures, XML and Web log databases and social networks, require much more sophisticated data structures such as trees and graphs. In these contexts, interesting patterns involve not only frequent object values (labels) appearing in the graphs (or trees) but also frequent specific topologies found in these structures. Recently, several techniques for tree and graph mining have been proposed in the literature. In this paper, we focus on constraint-based tree pattern mining. We propose to use tree automata as a mechanism to specify user constraints over tree patterns. We present the algorithm CoBMiner which allows user constraints specified by a tree automata to be incorporated in the mining process. An extensive set of experiments executed over synthetic and real data (XML documents and Web usage logs) allows us to conclude that incorporating constraints during the mining process is far more effective than filtering the interesting patterns after the mining process. 相似文献
45.
Persistent Scatterers Interferometry detects and measures ground subsidence in Lisbon 总被引:1,自引:0,他引:1
Sandra I.N. Heleno Luís G.S. Oliveira Maria J. Henriques 《Remote sensing of environment》2011,115(8):2152-2167
Results from the application of Persistent Scatterers Interferometry in Lisbon Metropolitan Area revealed two previously unknown subsiding urban areas: one (Laranjeiras) is located in the center of Lisbon; another (Vialonga) is to be found toward the North, in an industrial region crossed by Lisbon's main highway and railway lines. The two subsiding sectors are bordered by sharp velocity gradients, and the subsidence pattern appears partially delimited by mapped geologic faults. Surface geology and urbanization alone are unable to explain the phenomena. In the Vialonga area, the historical record of water pore pressure shows a clear decline of the levels (up to 65 m in 27 years), providing evidence of over-exploitation of groundwater resources. Limited information from wells drilled inside and outside the subsidence area points to a spatial correlation between the subsidence and the water pressure levels, and suggests that faults could be acting as hydraulic barriers in the aquifer system. The surface subsidence detected is probably caused by compaction of a clay-rich Oligocene-aged aquitard, led by over-exploitation of adjacent aquifers. The same Oligocene aquitard layer is present in the Laranjeiras area, immediately bellow a multi-layered sand-clay-limestone Miocene aquifer, but further work is needed to diagnose the possibility of over-exploitation of groundwater here. In this work we were able to independently confirm the PSI results, by comparing autonomous PSI results processed for the same geographical areas, and by comparing PSI with leveling and continuous GPS derived subsidence velocities, whose close match provided further ground validation of the space-borne PSI technique. 相似文献
46.
Liu A Nickerson A Troyer A Yin X Cary R Thornburg K Wang R Rugonyi S 《Computers & Structures》2011,89(11-12):855-867
Wall shear stresses (WSS) exerted by blood flow on cardiac tissues modulate growth and development of the heart. To study the role of hemodynamic conditions on cardiac morphogenesis, here, we present a methodology that combines imaging and finite element modeling to quantify the in vivo blood flow dynamics and WSS in the cardiac outflow tract (OFT) of early chicken embryos (day 3 out of 21-day incubation period). We found a distinct blood flow field and heterogeneous distribution of WSS in the chicken embryonic heart OFT, which have physiological implications for OFT morphogenesis. 相似文献
47.
Hernandez Prada JA Madden SL Ostrov DA Hernandez MA 《Journal of molecular graphics & modelling》2008,26(8):1365-1369
Intravascular clotting remains a major health problem in the United States, the most prominent being deep vein thrombosis, pulmonary embolism and thromboembolic stroke. Previous reports on the use of pyridine derivatives in cardiovascular drug development encourage us to pursue new types of compounds based on a pyridine scaffold. Eleven pyridine derivatives (oximes, semicarbazones, N-oxides) previously synthesized in our laboratories were tested as anticoagulants on pooled normal plasma using the prothrombin time (PT) protocol. The best anticoagulant within the oxime series was compound AF4, within the oxime N-oxide series was compound AF4-N-oxide, and within the semicarbazone series, compound MD1-30Y. We also used a molecular modeling approach to guide our efforts, and found that there was good correlation between coagulation data and computational energy scores. Molecular docking was performed to target the active site of thrombin with the DOCK v5.2 package. The results of molecular modeling indicate that improvement in anticoagulant activities can be expected by functionalization at the three-position of the pyridine ring and by N-oxide formation. Results reported here prove the suitability of DOCK in the lead optimization process. 相似文献
48.
Alejandro Echeverría Matías Améstica Francisca Gil Miguel Nussbaum Enrique Barrios Sandra Leclerc 《Computers in human behavior》2012
Computer Supported Collaborative Learning is a pedagogical approach that can be used for deploying educational games in the classroom. However, there is no clear understanding as to which technological platforms are better suited for deploying co-located collaborative games, nor the general affordances that are required. In this work we explore two different technological platforms for developing collaborative games in the classroom: one based on augmented reality technology and the other based on multiple-mice technology. In both cases, the same game was introduced to teach electrostatics and the results were compared experimentally using a real class. 相似文献
49.
Tobacco use is prevalent among youth with alcohol and other drug problems, yet this issue has received limited research and clinical attention. This study reports on a controlled evaluation of a cigarette smoking intervention with 54 adolescents in treatment for substance abuse, ages 13-18 (22% female). Participants were assessed at 4 time points. A greater proportion of participants in the treatment condition (n = 26) reported cessation attempts and point abstinence than did control participants (n = 28) at all time points. However, significant differences were found only for point abstinence at a 3-month follow-up. These findings provide initial support for the efficacy of a smoking cessation intervention delivered in the context of adolescent substance abuse treatment. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
50.
Hoshino-Browne Etsuko; Zanna Adam S.; Spencer Steven J.; Zanna Mark P.; Kitayama Shinobu; Lackenbauer Sandra 《Canadian Metallurgical Quarterly》2005,89(3):294
Cognitive dissonance and effects of self-affirmation on dissonance arousal were examined cross-culturally. In Studies 1 and 2, European Canadians justified their choices more when they made them for themselves, whereas Asian Canadians (Study 1) or Japanese (Study 2) justified their choices more when they made them for a friend. In Study 3, an interdependent self-affirmation reduced dissonance for Asian Canadians but not for European Canadians. In Study 4, when Asian Canadians made choices for a friend, an independent self-affirmation reduced dissonance for bicultural Asian Canadians but not for monocultural Asian Canadians. These studies demonstrate that both Easterners and Westerners can experience dissonance, but culture shapes the situations in which dissonance is aroused and reduced. Implications of these cultural differences for theories of cognitive dissonance and self-affirmation are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献