全文获取类型
收费全文 | 3294篇 |
免费 | 128篇 |
国内免费 | 10篇 |
专业分类
电工技术 | 72篇 |
综合类 | 1篇 |
化学工业 | 672篇 |
金属工艺 | 74篇 |
机械仪表 | 60篇 |
建筑科学 | 183篇 |
矿业工程 | 32篇 |
能源动力 | 97篇 |
轻工业 | 321篇 |
水利工程 | 15篇 |
石油天然气 | 18篇 |
武器工业 | 1篇 |
无线电 | 299篇 |
一般工业技术 | 476篇 |
冶金工业 | 512篇 |
原子能技术 | 43篇 |
自动化技术 | 556篇 |
出版年
2023年 | 24篇 |
2022年 | 28篇 |
2021年 | 43篇 |
2020年 | 26篇 |
2019年 | 49篇 |
2018年 | 63篇 |
2017年 | 66篇 |
2016年 | 66篇 |
2015年 | 64篇 |
2014年 | 76篇 |
2013年 | 246篇 |
2012年 | 122篇 |
2011年 | 173篇 |
2010年 | 123篇 |
2009年 | 154篇 |
2008年 | 157篇 |
2007年 | 119篇 |
2006年 | 141篇 |
2005年 | 106篇 |
2004年 | 74篇 |
2003年 | 62篇 |
2002年 | 80篇 |
2001年 | 47篇 |
2000年 | 57篇 |
1999年 | 54篇 |
1998年 | 68篇 |
1997年 | 52篇 |
1996年 | 41篇 |
1995年 | 38篇 |
1994年 | 49篇 |
1993年 | 52篇 |
1992年 | 41篇 |
1991年 | 29篇 |
1990年 | 30篇 |
1989年 | 33篇 |
1988年 | 31篇 |
1986年 | 28篇 |
1985年 | 42篇 |
1984年 | 56篇 |
1983年 | 39篇 |
1982年 | 35篇 |
1981年 | 46篇 |
1980年 | 50篇 |
1979年 | 52篇 |
1978年 | 32篇 |
1977年 | 26篇 |
1976年 | 35篇 |
1975年 | 30篇 |
1974年 | 32篇 |
1973年 | 27篇 |
排序方式: 共有3432条查询结果,搜索用时 15 毫秒
61.
Harry J. Robberecht Peter Hendrix Rudy Van Cauwenbergh Hendrik A. Deelstra 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1994,199(4):251-254
The dietary selenium (Se) intake in Belgium has been re-evaluated. Duplicate meal collection, wet acid destruction and flow injection hydride generation atomic absorption spectrometry were used as techniques. The daily intake ranged from 28.4 g (Liège, Walloon part of the country) to 61.1 g (Vilvoorde, central part of the country). Compared with intakes recently published for other countries, the actual Belgian value corresponds to intermediate ranges of Se intake.
Die aktuelle tägliche Selen-Aufnahme durch die Nahrung in Belgien, bestimmt durch doppelte Probenahme
Zusammenfassung Die Selen-Aufnahme durch die Nahrung in Belgien wurde neu bestimmt. Als Technik diente die doppelte Probenahme von Mahlzeiten, deren nasser Aufschluß und die Fließ-Injektions AAS mit Hydridgeneration. Die tägliche Aufnahme schwankt zwischen 28,4 und 61, 1 g. Im Vergleich zu Daten, die neuerdings aus anderen Ländern publiziert wurden, liegen die derzeitigen Werte aus Belgien im Mittelbereich.相似文献
62.
The integration of piezoelectric materials onto carbon fiber (CF) can add energy harvesting and self-power sensing capabilities enabling great potential for “Internet of Things” (IoT) applications in motion tracking, environmental sensing, and personal portable electronics. Herein, a CF-based smart composite is developed by integrating piezoelectric poly(3,4-ethylenedioxythiophene) (PEDOT)/CuSCN-coated ZnO nanorods onto the CF surfaces with no detrimental effect on the mechanical properties of the composite, forming composites using two different polymer matrices: highly flexible polydimethylsiloxane (PDMS) and more rigid epoxy. The PDMS-coated piezoelectric smart composite can serve as an energy harvester and a self-powered sensor for detecting variations in impact acceleration with increasing output voltage from 1.4 to 7.6 V under impact acceleration from 0.1 to 0.4 m s−2. Using epoxy as the matrix for a CF-reinforced plastic (CFRP) device with sensing and detection functions produces a voltage varying from 0.27 to 3.53 V when impacted at acceleration from 0.1 to 0.4 m s−2, with a lower output compared to the PDMS-coated device attributed to the greater stiffness of the matrix. Finally, spatially sensitive detection is demonstrated by positioning two piezoelectric structures at different locations, which can identify the location as well as the level of the impacting force from the fabricated device. 相似文献
63.
Harry McCarthy Abigail Koay Michael Dawson Kenneth B. Kent Panos Patros 《Software》2022,52(1):172-193
Tablets, smartphones, and wearables have limited resources. Applications on these devices employ a graphical user interface (GUI) for interaction with users. Language runtimes for GUIs employ dynamic memory management using garbage collection (GC). However, GC policies and algorithms are designed for data centers and cloud computing, but they are not necessarily ideal for resource-constrained embedded devices. In this article, we present GUI GC, a JavaFX GUI benchmark, which we use to compare the performance of the four GC policies of the Eclipse OpenJ9 Java runtime on a resource-constrained environment. Overall, our experiments suggest that the default policy Gencon registered significantly lower execution times than its counterparts. The region-based policy, Balanced, did not fully utilize blocking times; thus, using GUI GC, we conducted experiments with explicit GC invocations that measured significant improvements of up to 13.22% when multiple CPUs were available. Furthermore, we created a second version of GUI GC that expands on the number of controllable load-stressing dimensions; we conducted a large number of randomly configured experiments to quantify the performance effect that each knob has. Finally, we analyzed our dataset to derive suitable knob configurations for desired runtime, GC, and hardware stress levels. 相似文献
64.
65.
66.
We study the problem of learning parity functions that depend on at most k variables (k-parities) attribute-efficiently in the mistake-bound model. We design a simple, deterministic, polynomial-time algorithm for learning k-parities with mistake bound . This is the first polynomial-time algorithm to learn ω(1)-parities in the mistake-bound model with mistake bound o(n).Using the standard conversion techniques from the mistake-bound model to the PAC model, our algorithm can also be used for learning k-parities in the PAC model. In particular, this implies a slight improvement over the results of Klivans and Servedio (2004) [1] for learning k-parities in the PAC model.We also show that the time algorithm from Klivans and Servedio (2004) [1] that PAC-learns k-parities with sample complexity can be extended to the mistake-bound model. 相似文献
67.
Sparse CCA using a Lasso with positivity constraints 总被引:1,自引:0,他引:1
Canonical correlation analysis (CCA) describes the relationship between two sets of variables by finding linear combinations of the variables with maximal correlation. A sparse version of CCA is proposed that reduces the chance of including unimportant variables in the canonical variates and thus improves their interpretation. A version of the Lasso algorithm incorporating positivity constraints is implemented in tandem with alternating least squares (ALS), to obtain sparse canonical variates. The proposed method is demonstrated on simulation studies and a data set from market basket analysis. 相似文献
68.
The problem of computing the chromatic number of a P
5-free graph (a graph which contains no path on 5 vertices as an induced subgraph) is known to be NP-hard. However, we show
that for every fixed integer k, there exists a polynomial-time algorithm determining whether or not a P
5-free graph admits a k-coloring, and finding one, if it does. 相似文献
69.
Flynn Castles Stephen M. Morris Damian J. Gardiner Qasim M. Malik Harry J. Coles 《Journal of the Society for Information Display》2010,18(2):128-133
Abstract— The flexoelectro‐optic effect provides a fast‐switching mechanism (0.01–0.1 msec), suitable for use in field‐sequential‐color full‐motion‐video displays. An in‐plane electric field is applied to a short‐pitch chiral nematic liquid crystal aligned in the uniform standing helix (or Grandjean) texture. The switching mechanism is experimentally demonstrated in a single‐pixel test cell, and the display performance is investigated as a function of device parameters. A contrast ratio of 2000:1 is predicted. 相似文献
70.
Harry Bunt 《Computer Speech and Language》2011,25(2):222-245
This paper studies the multifunctionality of dialogue utterances, i.e. the phenomenon that utterances in dialogue often have more than one communicative function. It is argued that this phenomenon can be explained by analyzing the participation in dialogue as involving the performance of several types of activity in parallel, relating to different dimensions of communication. The multifunctionality of dialogue utterances is studied by (1) redefining the notion of ‘utterance’ in a rigorous manner (calling the revised notion ‘functional segment’), and (2) empirically investigating the multifunctionality of functional segments in a corpus of dialogues, annotated with a rich, multidimensional annotation schema. It is shown that, when communicative functions are assigned to functional segments, thereby eliminating every form of segmentation-related multifunctionality, an average multifunctionality is found between 1.8 and 3.6, depending on what is considered to count as a segment's communicative function. Moreover, a good understanding of the nature of the relations among the various multiple functions that a segment may have, and of the relations between functional segments and other units in dialogue segmentation, opens the way for defining a multidimensional computational update semantics for dialogue interpretation. 相似文献