全文获取类型
收费全文 | 7534篇 |
免费 | 379篇 |
国内免费 | 46篇 |
专业分类
电工技术 | 213篇 |
综合类 | 20篇 |
化学工业 | 1579篇 |
金属工艺 | 158篇 |
机械仪表 | 183篇 |
建筑科学 | 238篇 |
矿业工程 | 8篇 |
能源动力 | 511篇 |
轻工业 | 757篇 |
水利工程 | 86篇 |
石油天然气 | 153篇 |
武器工业 | 4篇 |
无线电 | 935篇 |
一般工业技术 | 1346篇 |
冶金工业 | 450篇 |
原子能技术 | 77篇 |
自动化技术 | 1241篇 |
出版年
2023年 | 171篇 |
2022年 | 375篇 |
2021年 | 520篇 |
2020年 | 369篇 |
2019年 | 373篇 |
2018年 | 479篇 |
2017年 | 333篇 |
2016年 | 377篇 |
2015年 | 232篇 |
2014年 | 357篇 |
2013年 | 588篇 |
2012年 | 389篇 |
2011年 | 441篇 |
2010年 | 280篇 |
2009年 | 240篇 |
2008年 | 226篇 |
2007年 | 206篇 |
2006年 | 172篇 |
2005年 | 152篇 |
2004年 | 124篇 |
2003年 | 102篇 |
2002年 | 117篇 |
2001年 | 62篇 |
2000年 | 65篇 |
1999年 | 76篇 |
1998年 | 123篇 |
1997年 | 107篇 |
1996年 | 71篇 |
1995年 | 78篇 |
1994年 | 51篇 |
1993年 | 50篇 |
1992年 | 40篇 |
1991年 | 23篇 |
1990年 | 28篇 |
1989年 | 42篇 |
1988年 | 46篇 |
1987年 | 28篇 |
1986年 | 28篇 |
1985年 | 42篇 |
1984年 | 49篇 |
1983年 | 41篇 |
1982年 | 26篇 |
1981年 | 21篇 |
1980年 | 28篇 |
1979年 | 23篇 |
1978年 | 18篇 |
1977年 | 21篇 |
1976年 | 30篇 |
1975年 | 15篇 |
1974年 | 16篇 |
排序方式: 共有7959条查询结果,搜索用时 93 毫秒
151.
Herein, the precipitation behavior of Mn-bearing dispersoids in Al-3Mg-0.8Mn (AA5454) alloy subjected to different heat treatments is investigated. The effects of Mn-bearing dispersoids on the tensile properties and recrystallization resistance of the abovementioned alloy during hot/cold rolling and postrolling annealing are evaluated. The results show that a low-temperature three-step heat treatment (275 °C/12 h + 375 °C/48 h + 425 °C/12 h) generates a higher number density of Mn-bearing dispersoids with finer sizes compared with the typical high-temperature heat treatment (430 °C/2 h + 480 °C/2 h + 525 °C/2 h), thus resulting in significantly improved tensile strengths of hot/cold-rolled sheets. After annealing at 300 °C, the yield strength (YS) of the alloy reached 196 MPa after hot rolling and 237 MPa after cold rolling, showing an improvement of 30%–32% over samples subjected to high-temperature heat treatment. In addition, the low-temperature heat treatment provides a higher recrystallization resistance after hot and cold rolling owing to the higher number density of Mn-bearing dispersoids and the lower fraction of dispersoid-free zones. The YS contributions of various strengthening components after hot and cold rolling are discussed based on constitutive models. The predicted yield strengths agree well with the experimental values. 相似文献
152.
Walid El-Shafai Noha A. El-Hag Ahmed Sedik Ghada Elbanby Fathi E. Abd El-Samie Naglaa F. Soliman Hussah Nasser AlEisa Mohammed E. Abdel Samea 《计算机、材料和连续体(英文)》2023,74(2):2905-2919
Medical image fusion is considered the best method for obtaining one image with rich details for efficient medical diagnosis and therapy. Deep learning provides a high performance for several medical image analysis applications. This paper proposes a deep learning model for the medical image fusion process. This model depends on Convolutional Neural Network (CNN). The basic idea of the proposed model is to extract features from both CT and MR images. Then, an additional process is executed on the extracted features. After that, the fused feature map is reconstructed to obtain the resulting fused image. Finally, the quality of the resulting fused image is enhanced by various enhancement techniques such as Histogram Matching (HM), Histogram Equalization (HE), fuzzy technique, fuzzy type Π, and Contrast Limited Histogram Equalization (CLAHE). The performance of the proposed fusion-based CNN model is measured by various metrics of the fusion and enhancement quality. Different realistic datasets of different modalities and diseases are tested and implemented. Also, real datasets are tested in the simulation analysis. 相似文献
153.
Mahmoud Ragab Mohammed W. Al-Rabia Sami Saeed Binyamin Ahmed A. Aldarmahi 《计算机、材料和连续体(英文)》2023,74(2):2889-2904
With the increasing and rapid growth rate of COVID-19 cases, the healthcare scheme of several developed countries have reached the point of collapse. An important and critical steps in fighting against COVID-19 is powerful screening of diseased patients, in such a way that positive patient can be treated and isolated. A chest radiology image-based diagnosis scheme might have several benefits over traditional approach. The accomplishment of artificial intelligence (AI) based techniques in automated diagnoses in the healthcare sector and rapid increase in COVID-19 cases have demanded the requirement of AI based automated diagnosis and recognition systems. This study develops an Intelligent Firefly Algorithm Deep Transfer Learning Based COVID-19 Monitoring System (IFFA-DTLMS). The proposed IFFA-DTLMS model majorly aims at identifying and categorizing the occurrence of COVID19 on chest radiographs. To attain this, the presented IFFA-DTLMS model primarily applies densely connected networks (DenseNet121) model to generate a collection of feature vectors. In addition, the firefly algorithm (FFA) is applied for the hyper parameter optimization of DenseNet121 model. Moreover, autoencoder-long short term memory (AE-LSTM) model is exploited for the classification and identification of COVID19. For ensuring the enhanced performance of the IFFA-DTLMS model, a wide-ranging experiments were performed and the results are reviewed under distinctive aspects. The experimental value reports the betterment of IFFA-DTLMS model over recent approaches. 相似文献
154.
Ahmed Abdu Alattab Mohammed Eid Ibrahim Reyazur Rashid Irshad Anwar Ali Yahya Amin A. Al-Awady 《计算机、材料和连续体(英文)》2023,74(2):2397-2412
This research proposes a machine learning approach using fuzzy logic to build an information retrieval system for the next crop rotation. In case-based reasoning systems, case representation is critical, and thus, researchers have thoroughly investigated textual, attribute-value pair, and ontological representations. As big databases result in slow case retrieval, this research suggests a fast case retrieval strategy based on an associated representation, so that, cases are interrelated in both either similar or dissimilar cases. As soon as a new case is recorded, it is compared to prior data to find a relative match. The proposed method is worked on the number of cases and retrieval accuracy between the related case representation and conventional approaches. Hierarchical Long Short-Term Memory (HLSTM) is used to evaluate the efficiency, similarity of the models, and fuzzy rules are applied to predict the environmental condition and soil quality during a particular time of the year. Based on the results, the proposed approaches allows for rapid case retrieval with high accuracy. 相似文献
155.
Shahad Alyousif Mohammed Dauwed Rafal Nader Mohammed Hasan Ali Mustafa Musa Jabar Ahmed Alkhayyat 《计算机、材料和连续体(英文)》2023,75(1):531-546
The number of mobile devices accessing wireless networks is skyrocketing due to the rapid advancement of sensors and wireless communication technology. In the upcoming years, it is anticipated that mobile data traffic would rise even more. The development of a new cellular network paradigm is being driven by the Internet of Things, smart homes, and more sophisticated applications with greater data rates and latency requirements. Resources are being used up quickly due to the steady growth of smartphone devices and multimedia apps. Computation offloading to either several distant clouds or close mobile devices has consistently improved the performance of mobile devices. The computation latency can also be decreased by offloading computing duties to edge servers with a specific level of computing power. Device-to-device (D2D) collaboration can assist in processing small-scale activities that are time-sensitive in order to further reduce task delays. The task offloading performance is drastically reduced due to the variation of different performance capabilities of edge nodes. Therefore, this paper addressed this problem and proposed a new method for D2D communication. In this method, the time delay is reduced by enabling the edge nodes to exchange data samples. Simulation results show that the proposed algorithm has better performance than traditional algorithm. 相似文献
156.
Muhammad Aadil Siddiqui M. H. Md Khir Zaka Ullah Muath Al Hasan Abdul Saboor Saeed Ahmed Magsi 《计算机、材料和连续体(英文)》2023,75(2):2859-2871
One of the most pressing concerns for the consumer market is the detection of adulteration in meat products due to their preciousness. The rapid and accurate identification mechanism for lard adulteration in meat products is highly necessary, for developing a mechanism trusted by consumers and that can be used to make a definitive diagnosis. Fourier Transform Infrared Spectroscopy (FTIR) is used in this work to identify lard adulteration in cow, lamb, and chicken samples. A simplified extraction method was implied to obtain the lipids from pure and adulterated meat. Adulterated samples were obtained by mixing lard with chicken, lamb, and beef with different concentrations (10%–50% v/v). Principal component analysis (PCA) and partial least square (PLS) were used to develop a calibration model at 800–3500 cm−1. Three-dimension PCA was successfully used by dividing the spectrum in three regions to classify lard meat adulteration in chicken, lamb, and beef samples. The corresponding FTIR peaks for the lard have been observed at 1159.6, 1743.4, 2853.1, and 2922.5 cm−1, which differentiate chicken, lamb, and beef samples. The wavenumbers offer the highest determination coefficient R2 value of 0.846 and lowest root mean square error of calibration (RMSEC) and root mean square error prediction (RMSEP) with an accuracy of 84.6%. Even the tiniest fat adulteration up to 10% can be reliably discovered using this methodology. 相似文献
157.
Martensitic phase transformations in the solution-treated and water-quenched binary Ti-Nb alloys in the range of 16–26 at% Nb, were examined. An ordered, base-centred orthorhombic martensite was observed for alloys containing up to 23.4 at% Nb. The substructure of this martensite was generally composed of twins and stacking faults, the presence of antiphase boundaries observed in the plates indicating that the martensite underwent ordering during quenching. Both order-disorder and M
s temperatures were observed to be affected by total interstitial content, higher contents increasing both temperatures. Increasing the niobium content to above 23.4% resulted in retention of the phase, this phase containing either athermal or diffuse depending upon niobium and total interstitial concentration. Finally, the microhardness of the Ti-Nb alloys examined was observed to decrease with increase in niobium and decrease in total interstitial content. 相似文献
158.
Zaher Al Aghbari Ibrahim Kamel Ahmed Mustafa 《Peer-to-Peer Networking and Applications》2011,4(4):391-409
Recently, many applications have used Peer-to-Peer (P2P) systems to overcome the current problems with client/server systems
such as non-scalability, high bandwidth requirement and single point of failure. In this paper, we propose an efficient scheme
to support efficient range query processing over structured P2P systems, while balancing both the storage load and access
load. The paper proposes a rotating token scheme to balance the storage load by placing joining nodes in appropriate locations
in the identifier space to share loads with already overloaded nodes. Then, to support range queries, we utilize an order-preserving
mapping function to map keys to nodes in order preserving way and without hashing. This may result in an access load imbalance
due to non-uniform distribution of keys in the identifier space. Thus, we propose an adaptive replication scheme to relieve
overloaded nodes by shedding some load on other nodes to balance the access load. We derive a formula for estimating the overhead
of the proposed adaptive replication scheme. In this study, we carry simulation experiments with synthetic data to measure
the performance of the proposed schemes. Our simulation experiments show significant gains in both storage load balancing
and access load balancing. 相似文献
159.
Zheng Z Ahmed N Mueller K 《IEEE transactions on visualization and computer graphics》2011,17(12):1959-1968
The unguided visual exploration of volumetric data can be both a challenging and a time-consuming undertaking. Identifying a set of favorable vantage points at which to start exploratory expeditions can greatly reduce this effort and can also ensure that no important structures are being missed. Recent research efforts have focused on entropy-based viewpoint selection criteria that depend on scalar values describing the structures of interest. In contrast, we propose a viewpoint suggestion pipeline that is based on feature-clustering in high-dimensional space. We use gradient/normal variation as a metric to identify interesting local events and then cluster these via k-means to detect important salient composite features. Next, we compute the maximum possible exposure of these composite feature for different viewpoints and calculate a 2D entropy map parameterized in longitude and latitude to point out promising view orientations. Superimposed onto an interactive track-ball interface, users can then directly use this entropy map to quickly navigate to potentially interesting viewpoints where visibility-based transfer functions can be employed to generate volume renderings that minimize occlusions. To give full exploration freedom to the user, the entropy map is updated on the fly whenever a view has been selected, pointing to new and promising but so far unseen view directions. Alternatively, our system can also use a set-cover optimization algorithm to provide a minimal set of views needed to observe all features. The views so generated could then be saved into a list for further inspection or into a gallery for a summary presentation. 相似文献
160.
This paper presents a new algorithm for de-noising global positioning system (GPS) and inertial navigation system (INS) data and estimates the INS error using wavelet multi-resolution analysis algorithm (WMRA)-based genetic algorithm (GA) with a well-designed structure appropriate for practical and real time implementations because of its very short training time and elevated accuracy. Different techniques have been implemented to de-noise and estimate the INS and GPS errors. Wavelet de-noising is one of th... 相似文献