全文获取类型
收费全文 | 646篇 |
免费 | 23篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 4篇 |
化学工业 | 149篇 |
金属工艺 | 28篇 |
机械仪表 | 14篇 |
建筑科学 | 36篇 |
矿业工程 | 2篇 |
能源动力 | 19篇 |
轻工业 | 76篇 |
水利工程 | 2篇 |
石油天然气 | 6篇 |
无线电 | 66篇 |
一般工业技术 | 82篇 |
冶金工业 | 43篇 |
原子能技术 | 8篇 |
自动化技术 | 137篇 |
出版年
2024年 | 6篇 |
2023年 | 8篇 |
2022年 | 27篇 |
2021年 | 19篇 |
2020年 | 11篇 |
2019年 | 10篇 |
2018年 | 17篇 |
2017年 | 8篇 |
2016年 | 24篇 |
2015年 | 18篇 |
2014年 | 23篇 |
2013年 | 43篇 |
2012年 | 30篇 |
2011年 | 29篇 |
2010年 | 38篇 |
2009年 | 37篇 |
2008年 | 20篇 |
2007年 | 24篇 |
2006年 | 25篇 |
2005年 | 18篇 |
2004年 | 21篇 |
2003年 | 29篇 |
2002年 | 14篇 |
2001年 | 9篇 |
2000年 | 14篇 |
1999年 | 17篇 |
1998年 | 9篇 |
1997年 | 10篇 |
1996年 | 5篇 |
1995年 | 5篇 |
1994年 | 11篇 |
1993年 | 4篇 |
1992年 | 7篇 |
1990年 | 2篇 |
1989年 | 4篇 |
1988年 | 4篇 |
1987年 | 6篇 |
1986年 | 4篇 |
1985年 | 5篇 |
1984年 | 5篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1979年 | 7篇 |
1978年 | 6篇 |
1977年 | 8篇 |
1976年 | 4篇 |
1975年 | 3篇 |
1974年 | 5篇 |
1970年 | 5篇 |
排序方式: 共有672条查询结果,搜索用时 15 毫秒
101.
Sport Stadia, Sporting Events and Urban Development: International Experience and the Ambitions of Durban 总被引:1,自引:0,他引:1
The paper considers the stadium construction and infrastructure projects underway for World Cup 2010. We ask whether and under
which conditions hosting such an event (along with the new facilities and infrastructural development required) will have
positive effects on urban development. By analysing the stadium project in Durban, the paper also presents evidence on whether
such positive effects may be enhanced by the attempt to create an image effect by seeking outstanding architectural quality
of the new stadia.
相似文献
Wolfgang MaennigEmail: |
102.
Andreea Cndea Ciurea Petra urlin tefan‐Ioan Stratul Andrada Soanc Alexandra Roman Mrioara Moldovan Lucian Tudoran B. Emoke Pall 《Microscopy research and technique》2019,82(10):1768-1778
Resin composite‐based dental materials can leach certain components into the oral environment, causing potentially harmful gingival biological effect. Gingival tissue is a rich source of mesenchymal stem cells (MSCs) that is easily accessible, and can be used as a complementary approach for the investigation of dental material biocompatibility. Using gingival MSCs (gMSCs), the present study aimed to investigate the cytotoxicity of two classes of restorative dental materials (ormocers and resin composites) used to restore class II cavities close to the gingival margin, in addition to analyzing the leached compounds from these resin composite‐based materials. Functionality assays (Colony‐forming unit, migratory potential, and proliferation assays) and a viability assay (MTT) were employed. Cells' aspect was observed by scanning electron microscopy (SEM). Leached monomers were also quantitated using high‐performance liquid chromatography (HPLC). The cytotoxicity of the biomaterials was highlighted by impaired functionality and diminished viability of gMSCs. Despite being variants of the same commercial material, the two ormocers behaved differently one material having a more negative impact on cell functionality than the other. Cells appeared to attach well to all materials. Main monomer molecules were mostly released by the tested materials. For all samples, an increased elution of monomers was recorded in artificial saliva as compared with culture medium. One composite material has released nearly eight times more urethane dimetacrylate in artificial saliva than in culture medium. Significantly lower gMSC viability scores were recorded for all the investigated samples in comparison with the control. 相似文献
103.
Andreea Groza Simona Liliana Iconaru Gabriel Jiga Patrick Chapon Sofia Gaiaschi Nicolae Verga Mircea Beuran Alina Mihaela Prodan Mihai Matei Serban Andrei Marinescu Roxana Trusca Daniela Predoi 《Polymer Engineering and Science》2019,59(12):2406-2412
The bio hydroxyapatite (HAp) was used from a long time in different medical and environmental applications. The HAp layers with a uniform surface were used for various medical applications such as orthopedic and dental metal implants. In this work, we reported on the influence of X‐ray radiation on the structural and morphological properties of composite layers based on HAp and polydimethylsiloxane (PDMS) deposited on titanium substrates. The HAp:PDMS layers were investigated by different complementary methods such as scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and glow discharge optical emission spectrometry (GDOES). FTIR spectral analysis showed that the molecular structure of the coatings was not changed after their irradiation even though, the depth profile analysis performed by GDOES indicated a depletion of Ca and P elements from the HAp:PDMS irradiated samples. By SEM, we showed that the morphological features of the coatings were also changed, as the irradiated layers are delaminated. The biological assays confirmed that the antibacterial activity of HAp:PDMS composite layers increased after irradiation. The results obtained in this study highlighted that the biological properties of HAp:PDMS layers could be influenced by irradiation. POLYM. ENG. SCI., 59:2406–2412, 2019. © 2019 Society of Plastics Engineers 相似文献
104.
105.
Corina Danciu Szilvia Berkó Gábor Varju Boglárka Balázs Lajos Kemény István Balázs Németh Andreea Cioca Alexandra Petru? Cristina Dehelean Citu Ioan Cosmin Elena Amaricai Claudia Crina Toma 《International journal of molecular sciences》2015,16(7):15425-15441
A lamellar lyotropic liquid crystal genistein-based formulation (LLC-Gen) was prepared in order to increase the aqueous solubility of the lipophilic phytocompound genistein. The formulation was applied locally, in a murine model of melanoma, with or without electroporation. The results demonstrated that, when the formulation was applied by electroporation, the tumors appeared later. During the 21 days of the experiment, the LLC-Gen formulation decreased the tumor volume, the amount of melanin and the degree of erythema, but when electroporation was applied, all these parameters indicated a better prognosis even (lower tumor volume, amount of melanin and degree of erythema). Although hematoxylin–eosin (HE) staining confirmed the above events, application of the LLC-Gen formulation by electroporation did not lead to a significant effect in terms of the serum concentrations of the protein S100B and serum neuron specific enolase (NSE), or the tissue expression of the platelet-derived growth factor receptor β (PDGFRβ) antibody. 相似文献
106.
Adriana Marinoiu Elena Carcadea Ada Sacca Alessandra Carbone Claudia Sisu Andreea Dogaru Mircea Raceanu Mihai Varlam 《International Journal of Hydrogen Energy》2021,46(22):12242-12253
Here in, we describe an ultrafast, single-step microwave irradiation route (MW) to prepare graphene supported Pt nanoparticles, during which the small Pt nanoparticles are distributed uniformly on a reduced graphene oxide surface. This route provides evident advantages namely low cost, easiness, low time consuming and high yield in comparison to actual chemical methods to develop efficient Pt/rGO catalyst with Pt content close to state-of-the-art commercial composition. The structure and composition of prepared samples have been studied by specific techniques, while the electrocatalytic stability has been studied using ex-situ and in-situ measurements. High performance and electrochemically stable catalyst for PEM fuel cells was developed using the sample with highest loading and good dispersion. The fabricated Pt-rGO-based MEA was investigated for durability under fuel starvation in comparison with commercial Pt/C-based MEA. The electrocatalytic activity was investigated and the electrochemical response revealed the higher stability during accelerated degradation test under fuel starvation in comparison with commercial Pt/C. This study promotes the applicability of described preparation method to noble or transition metal nanoparticles embedded on graphene-based materials. 相似文献
107.
Li Zelong Khurshid Adnan Rauf Abdur Qayyum Sadia Calin Adrian Cantemir Iancu Laura Andreea Wang Xinyu 《Clean Technologies and Environmental Policy》2023,25(1):195-209
Clean Technologies and Environmental Policy - The United Nations 2030 agenda states various sustainable development goals (SDGs) to counter climate change affecting individuals' health and... 相似文献
108.
Jianming Zhang Sarah Adel Bargal Zhe Lin Jonathan Brandt Xiaohui Shen Stan Sclaroff 《International Journal of Computer Vision》2018,126(10):1084-1102
We aim to model the top-down attention of a convolutional neural network (CNN) classifier for generating task-specific attention maps. Inspired by a top-down human visual attention model, we propose a new backpropagation scheme, called Excitation Backprop, to pass along top-down signals downwards in the network hierarchy via a probabilistic Winner-Take-All process. Furthermore, we introduce the concept of contrastive attention to make the top-down attention maps more discriminative. We show a theoretic connection between the proposed contrastive attention formulation and the Class Activation Map computation. Efficient implementation of Excitation Backprop for common neural network layers is also presented. In experiments, we visualize the evidence of a model’s classification decision by computing the proposed top-down attention maps. For quantitative evaluation, we report the accuracy of our method in weakly supervised localization tasks on the MS COCO, PASCAL VOC07 and ImageNet datasets. The usefulness of our method is further validated in the text-to-region association task. On the Flickr30k Entities dataset, we achieve promising performance in phrase localization by leveraging the top-down attention of a CNN model that has been trained on weakly labeled web images. Finally, we demonstrate applications of our method in model interpretation and data annotation assistance for facial expression analysis and medical imaging tasks. 相似文献
109.
Haifa Alharthi Diana Inkpen Stan Szpakowicz 《Journal of Intelligent Information Systems》2018,51(1):139-160
The act of reading has benefits for individuals and societies, yet studies show that reading declines, especially among the young. Recommender systems can help stop such decline. We present a survey of recommender systems in the domain of books. We have categorized the systems into six classes, and highlighted the main trends, issues, evaluation approaches and datasets. Other research areas, such as psychology, are consulted to understand users’ books choices and reading models. 相似文献
110.
Jianming Zhang Shugao Ma Mehrnoosh Sameki Stan Sclaroff Margrit Betke Zhe Lin Xiaohui Shen Brian Price Radomír Měch 《International Journal of Computer Vision》2017,124(2):169-186
We study the problem of salient object subitizing, i.e. predicting the existence and the number of salient objects in an image using holistic cues. This task is inspired by the ability of people to quickly and accurately identify the number of items within the subitizing range (1–4). To this end, we present a salient object subitizing image dataset of about 14 K everyday images which are annotated using an online crowdsourcing marketplace. We show that using an end-to-end trained convolutional neural network (CNN) model, we achieve prediction accuracy comparable to human performance in identifying images with zero or one salient object. For images with multiple salient objects, our model also provides significantly better than chance performance without requiring any localization process. Moreover, we propose a method to improve the training of the CNN subitizing model by leveraging synthetic images. In experiments, we demonstrate the accuracy and generalizability of our CNN subitizing model and its applications in salient object detection and image retrieval. 相似文献