全文获取类型
收费全文 | 1839篇 |
免费 | 105篇 |
国内免费 | 7篇 |
专业分类
电工技术 | 25篇 |
综合类 | 2篇 |
化学工业 | 392篇 |
金属工艺 | 68篇 |
机械仪表 | 132篇 |
建筑科学 | 31篇 |
矿业工程 | 4篇 |
能源动力 | 83篇 |
轻工业 | 131篇 |
水利工程 | 12篇 |
石油天然气 | 4篇 |
武器工业 | 1篇 |
无线电 | 290篇 |
一般工业技术 | 386篇 |
冶金工业 | 113篇 |
原子能技术 | 21篇 |
自动化技术 | 256篇 |
出版年
2024年 | 1篇 |
2023年 | 35篇 |
2022年 | 30篇 |
2021年 | 76篇 |
2020年 | 54篇 |
2019年 | 71篇 |
2018年 | 58篇 |
2017年 | 57篇 |
2016年 | 78篇 |
2015年 | 51篇 |
2014年 | 111篇 |
2013年 | 141篇 |
2012年 | 131篇 |
2011年 | 145篇 |
2010年 | 93篇 |
2009年 | 98篇 |
2008年 | 94篇 |
2007年 | 98篇 |
2006年 | 78篇 |
2005年 | 50篇 |
2004年 | 50篇 |
2003年 | 46篇 |
2002年 | 22篇 |
2001年 | 41篇 |
2000年 | 24篇 |
1999年 | 25篇 |
1998年 | 43篇 |
1997年 | 24篇 |
1996年 | 19篇 |
1995年 | 12篇 |
1994年 | 9篇 |
1993年 | 16篇 |
1992年 | 12篇 |
1991年 | 3篇 |
1990年 | 5篇 |
1989年 | 9篇 |
1988年 | 4篇 |
1987年 | 6篇 |
1986年 | 3篇 |
1985年 | 4篇 |
1983年 | 3篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1977年 | 7篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1973年 | 3篇 |
1964年 | 1篇 |
1941年 | 1篇 |
排序方式: 共有1951条查询结果,搜索用时 468 毫秒
51.
Effect of NaOH on the decomposition of halogenated hydrocarbon by supercritical water oxidation 总被引:1,自引:0,他引:1
Sang-Ha Son Jong-Hwa Kim Hyeon-Chul Lee Chang-Ha Lee 《Korean Journal of Chemical Engineering》2006,23(3):385-390
To protect alloys from corrosion phenomena in the supercritical water oxidation (SCWO) process, the effects of neutralizer
on the conversion and corrosion were investigated. The surface morphologies of all the alloy coupons exposed to 2,4-Dichlorophenol
(2,4-DCP) in the SCWO were significantly changed in microscopic images. The theoretical amount of NaOH as a neutralizer was
calculated under the assumption of complete oxidation of 2,4-DCP. The pre-dosed NaOH in the range of 100% to 300% stoichiometric
amount could not affect significantly the pH value in the SCWO. Moreover, the pH = 7 was not achieved until 700% stoichiometric
amount of NaOH was pre-dosed to the reactor. It is noted that the conversion rate recorded over 99% without oxidant when 800%
of NaOH was pre-dosed into the reactor. In addition, under the addition of H2O2 as an oxidant, the increased amount of NaOH led to the improvement of conversion rate. The pre-dosed NaOH may contribute
to the conversion rate of 2,4-DCP in the SCWO. However, due to low solubility of salt in the SCWO, the fouling problem should
be solved in the SCWO process. 相似文献
52.
53.
Recently many statistical learning techniques have been applied to the prediction of financial variables. The aim of this paper is to conduct a comprehensive study of the applications of statistical learning techniques to predict the trend of the return of high-frequency Korea composite stock price index (KOSPI) 200 index data using the information from the one-minute time series of spot index, futures index, and foreign exchange rate. Through experiments, it is observed that the spot index change is better predictable with high-frequency time series data and the futures index information significantly improves the prediction accuracy of the return trends of the spot index for high-frequency index data, while the information of exchange rate does not. Also, dimension reduction process before training helps to increase the accuracy and dramatically for some classifiers. In addition, the trained classifiers with which a virtual trading strategy is applied to, noticeable better profits can be achieved than just a buy-and-hold-like strategy. 相似文献
54.
We have studied grain-shape dependence of Kelvin probe force microscopy of SrBi2Ta2O9 thin films on epitaxial La0.5Sr0.5CoO3/LaAlO3 substrates. By changing the growth condition in pulsed laser deposition, we have grown the SrBi2Ta2O9 thin films with various grain shapes. The shape and the orientation of SrBi2Ta2O9 the thin films with various growth conditions have been analyzed by X-ray diffraction and scanning electron microscope. The large number of the long rectangular grains was observed accompanied with relatively larger (220) peaks than other peaks. From the Kelvin probe force microscope study, it has been observed that the long rectangular grains showed characteristics of easy ferroelectric domain switching at a low writing bias and weaker influence of surface charges. 相似文献
55.
This paper provides generalized analysis of active filters used as electromagnetic interference (EMI) filters and active-power filters. Insertion loss and impedance increase of various types of active-filter topologies are described with applicable requirements and limitations as well as the rationale for selecting active-filter topology according to different applications. 相似文献
56.
Chul-Ho Park Mi-Sook Won Chul-Su Lee Won-Hyo Cha Young-Gook Son 《Journal of Electroceramics》2006,17(2-4):619-623
PZT thin films and interlayers were fabricated by the radio frequency (r.f.) Magnetron-sputtering from the Pb1.1Zr0.53Ti0.47O3, PbO and TiO2 target. As a result of the XPS depth profile analysis, we can confirm that the substrate temperature affects the oxidation
condition of each element of interlayers and the PZT film. Compared to the PZT/Pt structure, the dielectric and pyroelectric
properties of PZT thin films inserted by interlayers were measured to a relatively high value. In particular, the PZT/PbO
structure had the highest pyroelectric properties (P = 189.4 μC/cm2K; F
D = 12.7×10−6 Pa−1/2; F
V = 0.018 m2/C). 相似文献
57.
The use of Static Two Phase Locking Protocols (S2PL) for concurrency control in real-time database systems (RTDBS) has received little attention in the past. Actually, real-time S2PL (RT-S2PL) protocols do possess some desirable features making them suitable for RTDBS, especially for distributed real-time database systems (DRTDBS) in which remote locking is required and distributed deadlock is possible. In this paper, different RT-S2PL protocols are proposed. They differ in their methods of reducing the blocking time of higher priority transactions. Their performance is studied and compared with a real-time dynamic two phase locking protocol (RT-D2PL), called Hybrid Two Phase Locking (Hb2PL). The impact of different system and workload parameters, such as mean inter-arrival time of transactions, number of remote lock requests of a transaction, communication overhead for sending messages, and database size on their performance have been examined. The performance results indicate that the RT-S2PL protocols are suitable for DRTDBS in which the proportion of local locks of a transaction is small and the communication overhead for locking is high. 相似文献
58.
Kang K.-D. Son S.H. Stankovic J.A. 《Knowledge and Data Engineering, IEEE Transactions on》2004,16(10):1200-1216
The demand for real-time data services is increasing in many applications including e-commerce, agile manufacturing, and telecommunications network management. In these applications, it is desirable to execute transactions within their deadlines, i.e., before the real-world status changes, using fresh (temporally consistent) data. However, meeting these fundamental requirements is challenging due to dynamic workloads and data access patterns in these applications. Further, transaction timeliness and data freshness requirements may conflict. We define average/transient deadline miss ratio and new data freshness metrics to let a database administrator specify the desired quality of real-time data services for a specific application. We also present a novel QoS management architecture for real-time databases to support the desired QoS even in the presence of unpredictable workloads and access patterns. To prevent overload and support the desired QoS, the presented architecture applies feedback control, admission control, and flexible freshness management schemes. A simulation study shows that our QoS-aware approach can achieve a near zero miss ratio and perfect freshness, meeting basic requirements for real-time transaction processing. In contrast, baseline approaches fail to support the desired miss ratio and/or freshness in the presence of unpredictable workloads and data access patterns. 相似文献
59.
Hyunseok Oh Jisun Kim Hyejeong Son Byeng D. Youn Byung C. Jung 《Structural and Multidisciplinary Optimization》2016,54(6):1527-1541
In recent years, virtual testing has played an increasingly important role in the design and evaluation of engineered products. However, it is challenging to build the highly accurate computational models for virtual testing. Blind and recognized uncertainties are often unintentionally incorporated. These uncertainties consequently decrease the predictive capability of the models. To this end, this paper proposes a systematic approach for model refinement that minimizes the impact of unrecognized blind and recognized epistemic uncertainties in computational modeling. The approach consists of three steps: model invalidity analysis (MIA), development of an invalidity reasoning tree (IRT), and invalidity sensitivity analysis (ISA). First, in the MIA, possible causes that lead to discrepancies between the experimental and simulation responses are identified through brainstorming. Next, the IRT is built using the affinity diagram. It sequentially lists and screens potential candidate issues for model refinement at the stages of conceptual, mathematical, and computational modeling. Finally, the ISA quantifies the effect of incorporating updates in the model to address potential candidate issues with the goal of reducing the impact of the blind and recognized uncertainties. The most critical candidates are determined by using a weighted decision matrix. To demonstrate the effectiveness of the proposed approach, a case study examining a smartphone liquid crystal display fracture is presented. 相似文献
60.
Minh Son Phan Étienne Baudrier Loïc Mazo Mohamed Tajine 《Journal of Mathematical Imaging and Vision》2017,57(2):164-182
This paper introduces a new method for estimating the angular difference between two tomographic projections belonging to a set of projections taken at unknown directions in 2D and 3D. Our method relies on the projection neighbor selection in projection moment space, the calculation of the angular differences between these neighboring projections using moment properties and a projection moment neighborhood graph. The accuracy and the robustness of our method are shown on a test database including fifty 2D and 3D gray-level images at different resolutions and with different levels of noise. 相似文献