全文获取类型
收费全文 | 303篇 |
免费 | 11篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 28篇 |
化学工业 | 63篇 |
金属工艺 | 6篇 |
机械仪表 | 10篇 |
建筑科学 | 9篇 |
能源动力 | 8篇 |
轻工业 | 22篇 |
水利工程 | 1篇 |
无线电 | 26篇 |
一般工业技术 | 58篇 |
冶金工业 | 41篇 |
原子能技术 | 13篇 |
自动化技术 | 31篇 |
出版年
2023年 | 2篇 |
2022年 | 7篇 |
2021年 | 5篇 |
2020年 | 3篇 |
2019年 | 3篇 |
2018年 | 8篇 |
2017年 | 6篇 |
2016年 | 4篇 |
2014年 | 4篇 |
2013年 | 19篇 |
2012年 | 11篇 |
2011年 | 17篇 |
2010年 | 8篇 |
2009年 | 13篇 |
2008年 | 21篇 |
2007年 | 13篇 |
2006年 | 12篇 |
2005年 | 17篇 |
2004年 | 10篇 |
2003年 | 17篇 |
2002年 | 4篇 |
2001年 | 4篇 |
2000年 | 6篇 |
1999年 | 7篇 |
1998年 | 15篇 |
1997年 | 11篇 |
1996年 | 8篇 |
1995年 | 2篇 |
1994年 | 7篇 |
1993年 | 6篇 |
1992年 | 3篇 |
1991年 | 4篇 |
1990年 | 1篇 |
1989年 | 5篇 |
1988年 | 4篇 |
1987年 | 1篇 |
1986年 | 3篇 |
1985年 | 4篇 |
1984年 | 3篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1978年 | 2篇 |
1977年 | 3篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1968年 | 1篇 |
1936年 | 1篇 |
排序方式: 共有316条查询结果,搜索用时 15 毫秒
111.
With the penetration of the IoT and data science, new manufacturing initiatives are accelerating. However, conventional approaches have emphasized the use of machine-based data. A need exists to realize more productive work styles considering the abilities and physical condition of operators. In this paper, we propose a production planning method to allocate machines and operators with different skill level optimally. After formulating a combinatorial auction mechanism, developing a schedule that minimizes the total production cost, we verify that the proposed method can realize human-centered production planning by combining the schedules with different evaluation indices. 相似文献
112.
Goetz Graefe Felix Halim Stratos Idreos Harumi Kuno Stefan Manegold Bernhard Seeger 《The VLDB Journal The International Journal on Very Large Data Bases》2014,23(2):303-328
Adaptive indexing initializes and optimizes indexes incrementally, as a side effect of query processing. The goal is to achieve the benefits of indexes while hiding or minimizing the costs of index creation. However, index-optimizing side effects seem to turn read-only queries into update transactions that might, for example, create lock contention. This paper studies concurrency control and recovery in the context of adaptive indexing. We show that the design and implementation of adaptive indexing rigorously separates index structures from index contents; this relaxes constraints and requirements during adaptive indexing compared to those of traditional index updates. Our design adapts to the fact that an adaptive index is refined continuously and exploits any concurrency opportunities in a dynamic way. A detailed experimental analysis demonstrates that (a) adaptive indexing maintains its adaptive properties even when running concurrent queries, (b) adaptive indexing can exploit the opportunity for parallelism due to concurrent queries, (c) the number of concurrency conflicts and any concurrency administration overheads follow an adaptive behavior, decreasing as the workload evolves and adapting to the workload needs. 相似文献
113.
Bactericidal activity of copper-deposited TiO2 thin film under weak UV light illumination 总被引:2,自引:0,他引:2
The bactericidal activity of copper-deposited titanium dioxide thin film (Cu/TiO2) was investigated under very weak ultraviolet (UV) light illumination. To elucidate the roles of the film photocatalyst and the deposited copper in the bactericidal activity, cells from a copper-resistant Escherichia coli (E. coli) strain were utilized. A decrease in survival rate was not observed with the copper-resistant cells under dark conditions, but when illuminated with a very weak UV intensity of 1 microW/cm2, the survival rate decreased, suggesting photocatalytic bactericidal activity. The decay curve of survival on the Cu/TiO2 film under very weak UV light illumination consisted of two steps, similar to the survival change of normal E. coli on TiO2 films under rather strong UV illumination. The first step is due to the partial decomposition of the outer membrane in the cell envelope by a photocatalytic process, followed by permeation of the copper ions into the cytoplasmic membrane. The second step is due to a disorder of the cytoplasmic membrane caused by the copper ions, which results in a loss of the cell's integrity. These processes explain why the Cu/TiO2 film system shows an effective bactericidal activity even under very weak UV light illumination. 相似文献
114.
ADAM is a recently discovered gene family that encodes proteins with a disintegrin and metalloproteinase. ADAMTS-1 is a gene encoding a new member protein of the ADAM family with the thrombospondin (TSP) type I motif, the expression of which is associated with inflammatory processes. In the present study, we have characterized the exon/intron organization of the mouse ADAMTS-1 gene. The ADAMTS-1 gene is composed of nine exons, all of which are present within the 9.2-kb genomic region. Among the nine exons, exons 1, 5, and 6 encode a proprotein domain, a disintegrin-like domain, and a TSP type I motif, respectively, of the ADAMTS-1 protein, suggesting that there is a correlation between exon/intron organization and functional domains. In addition, the exon/ intron organization of the ADAMTS-1 gene is very different from that of the metalloproteinase-like/disintegrin-like/ cysteine-rich protein gene (MDC) (ADAM11), suggesting that the genomic structure of ADAM family genes is not necessarily conserved. Furthermore, fluorescence in situ hybridization revealed that the ADAMTS-1 gene is located in region C3-C5 of chromosome 16, to which none of the previously identified ADAM genes have been mapped. 相似文献
115.
Bellare and Goldwasser showed that if the modulus N is guaranteed to be the product of O(log log ¦N¦) distinct odd primes, then quadratic residuosity has a competitive interactive proof system (with reasonably large communication complexity). In this paper we show that if the modulus N is guaranteed to be the product of O(log ¦N¦) distinct odd primes, then quadratic residuosity has a competitive interactive proof system with low communication complexity. 相似文献
116.
Tomas Hudlicky Fan Rulin Toshiya Tsunoda Hector Luna Catherine Andersen John D. Price 《Israel journal of chemistry》1991,31(3):229-238
Bacterial oxygenation of halogenated aromatic compounds yields arene cis-diols of type 2 of high enantiomeric purity. Further oxygenation of these extremely versatile synthetic intermediates provides for stereo- and regioselective introduction of additional functionalities such as hydroxyl groups. Several rational methods of oxygenation (epoxidation, osmylation, singlet oxygen addition, and ozonolysis) are used to produce, in short synthetic routes, cyclitol derivatives of medicinal importance. Proper symmetry considerations lead to the development of enantiodivergent synthetic design of target compounds from a single enantiomer of a starting diol. These principles are illustrated on the short syntheses of (+)- and (-)-pinitol. Stereocontrolled oxidative transformation of diols of type 2 are exemplified in the synthesis of conduritol C and dihydroconduritol C. Full experimental details are provided for all compounds. A guide to the stereorational design of any stereoisomer of cyclohexane (poly)ols or carbohydrates is provided at the end of the paper. 相似文献
117.
T Tsuboi M Ohi K Chin H Hirata N Otsuka H Kita K Kuno 《Canadian Metallurgical Quarterly》1997,112(4):1000-1007
STUDY OBJECTIVE: The aim of this study was to determine whether intermittent positive pressure ventilation through a nasal mask (NIPPV) applied during exercise in patients with pulmonary tuberculosis sequelae (PTS) could improve arterial blood gas measurements, ameliorate breathlessness, and increase exercise endurance. PATIENTS: Seven PTS patients with a severe restrictive ventilatory defect (mean [SD] vital capacity, 1.02 [0.25] I) enrolled in this study had experienced NIPPV previously, and were familiar with the procedure. DESIGN: The patients underwent four constant-load cycle ergometer tests in the supine position to tolerance. The tests were performed with and without NIPPV, while breathing normoxic air (Air) or supplemental oxygen (O2; 35%). NIPPV was delivered during exercise in a controlled, volume-cycled mechanical ventilation mode, and the ventilator settings were modulated manually to meet patients' respiratory demands as estimated from the airway pressure waveform and the patient's breathlessness. RESULTS: All patients matched their breathing to the ventilator cycle during most of the exercise while receiving NIPPV. NIPPV significantly prolonged their exercise endurance time, from a mean (SD) of 180 (58) s to 310 (96) s in Air, and from 227 (64) s to 465 (201) s in O2. During exercise, NIPPV effectively decreased their breathlessness and significantly improved arterial blood gas measurements. CONCLUSIONS: NIPPV applied during exercise can effectively support ventilation, significantly ameliorate breathlessness, and consequently improve exercise endurance in patients with PTS. 相似文献
118.
119.
Yoshinobu Naoshima Hiroshi Mukaidani Shohei Shibayama Toshiya Murata 《Journal of chemical ecology》1986,12(1):127-133
A nine-step synthesis is described for a diastereomeric mixture of 15,19,23-trimethylheptatriacontane, a contact sex pheromone ofGlossina morsitans morsitans Westwood. The compound has been synthesized by means of double alkylation of diethyl 3-oxoglutarate (DEOG) with 3-methyl-2-heptadecenyl methanesulfonate, which was readily prepared from 1-hexadecene, as the key step.This study constitutes Part XII of Selective Alkylation of Diethyl 3-Oxoglutarate. Part XI of this series, see Naoshima et al. (1984). 相似文献
120.
Summary Mechanical properties of polycyclo-olefins (PCOs) were investigated in the vicinity of the glass transition temperature (Tg). According to tensile tests, the fracture modes of PCOs such as brittle, ductile, and impact processes were largely dependent
on the elongation speeds below Tg. In addition, the stress-strain curves were found to be superimposed by the shift factors on transverse and longitudinal
axes, giving a typical master curve for tensile fracture behavior. 相似文献