全文获取类型
收费全文 | 689篇 |
免费 | 11篇 |
国内免费 | 6篇 |
专业分类
电工技术 | 3篇 |
综合类 | 2篇 |
化学工业 | 23篇 |
金属工艺 | 8篇 |
机械仪表 | 16篇 |
建筑科学 | 4篇 |
能源动力 | 8篇 |
轻工业 | 2篇 |
水利工程 | 1篇 |
石油天然气 | 1篇 |
无线电 | 23篇 |
一般工业技术 | 29篇 |
冶金工业 | 560篇 |
原子能技术 | 6篇 |
自动化技术 | 20篇 |
出版年
2023年 | 3篇 |
2022年 | 1篇 |
2021年 | 6篇 |
2020年 | 4篇 |
2019年 | 3篇 |
2018年 | 7篇 |
2017年 | 3篇 |
2016年 | 1篇 |
2015年 | 4篇 |
2014年 | 6篇 |
2013年 | 6篇 |
2012年 | 4篇 |
2011年 | 8篇 |
2010年 | 5篇 |
2009年 | 6篇 |
2008年 | 6篇 |
2007年 | 1篇 |
2006年 | 6篇 |
2005年 | 7篇 |
2004年 | 5篇 |
2003年 | 3篇 |
2002年 | 3篇 |
2001年 | 5篇 |
2000年 | 5篇 |
1999年 | 22篇 |
1998年 | 205篇 |
1997年 | 119篇 |
1996年 | 77篇 |
1995年 | 38篇 |
1994年 | 36篇 |
1993年 | 29篇 |
1992年 | 5篇 |
1991年 | 4篇 |
1990年 | 6篇 |
1989年 | 9篇 |
1988年 | 9篇 |
1987年 | 5篇 |
1986年 | 5篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1980年 | 4篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1977年 | 7篇 |
1976年 | 9篇 |
排序方式: 共有706条查询结果,搜索用时 0 毫秒
51.
Viswanath Venkatesh James Y. L. Thong Frank K. Y. Chan Paul Jen‐Hwa Hu Susan A. Brown 《Information Systems Journal》2011,21(6):527-555
This study presents two extensions to the two‐stage expectation‐confirmation theory of information systems (IS) continuance. First, we expand the belief set from perceived usefulness in the original IS continuance model to include three additional predictors identified in the unified theory of acceptance and use of technology, namely effort expectancy, social influence and facilitating conditions. Second, we ground the IS continuance model in the context of transactional systems that involve transmission of personal and sensitive information and include trust as a key contextual belief in the model. To test the expanded IS continuance model, we conducted a longitudinal field study of 3159 Hong Kong citizens across two electronic government (e‐government) technologies that enable citizens' access to government services. In general, the results support the expanded model that provides a rich understanding of the changes in the pre‐usage beliefs and attitudes through the emergent constructs of disconfirmation and satisfaction, ultimately influencing IS continuance intention. Finally, we discuss the theoretical and practical implications of the expanded model. 相似文献
52.
53.
54.
H Kook JH Rhee SE Lee SY Kang SS Chung KW Cho YH Baik 《Canadian Metallurgical Quarterly》1999,365(2-3):267-272
Recently we reported that Vibrio vulnificus hemolysin, an exotoxin produced by V. vulnificus, dilates rat thoracic aorta via elevated cGMP levels without affecting nitric oxide synthase. We investigated the mechanism further by observing the guanylyl cyclase activities in cytosolic, membrane, unfractionated, or reconstituted preparations. Hemolysin did not activate guanylyl cyclase in the membrane or cytosolic fraction, while it activated guanylyl cyclase in unfractionated or reconstituted preparation. The increased activity was not inhibited by the HS-142-1, a microbial polysaccharide which antagonizes atrial natriuretic peptide receptor, or 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ), a soluble guanylyl cyclase inhibitor. However, it was attenuated by 6-(phenylamino)-5,8-quinolinedione (LY 83.583), which inhibits the catalytic domain of both guanylyl cyclases, and by cholesterol, which blocks hemolysin-incorporation into the membrane. Removing ATP, a cofactor of particulate guanylyl cyclase, attenuated the activation and ATPgammaS, a non-phosphorylating analog, restored it. These results suggest that V. vulnificus hemolysin activates particulate guanylyl cyclase via hemolysin incorporation into the vascular smooth muscle cell membrane in cooperation with certain unidentified cytosolic component(s). 相似文献
55.
R Liljequist A Haapalinna M Ahlander YH Li PT M?nnist? 《Canadian Metallurgical Quarterly》1997,82(2):195-202
DNA-based immunization is a promising new technique for generating antibodies in laboratory animals for diagnostic purposes in biological science. The main advantages are the elimination of time and labor and the technically demanding steps of antigen purification. The DNA sequence of the protein of interest, cloned in a suitable in vivo expression vector that is administered intramuscularly or intradermally, is sufficient to induce an immune response in animals. We report the induction of antibodies to tobacco mosaic virus (TMV) coat protein (CP) as a highly immunogenic structural protein and potato virus Y (PVY) P1 protein (P1) as a nonstructural protein. The appropriate nucleotide sequences were introduced in a mammalian expression vector (pSG5) and injected intramuscularly into New Zealand White rabbits (Oryctolagus cuniculus). By 10 days post-injection (dpi) a specific immune response was detected against TMV-CP, while it took about 5 weeks for a response to PVY P1. In both cases the antibody titers were significantly above the corresponding pre-immune serum, however, they were considerably below the titer of the matching conventionally produced antiserum. To our knowledge, this is the first report of DNA-based immunization in order to generate antibodies to plant viral proteins, but further improvements are necessary to increase antibody titers before this promising new technique can be introduced broadly in plant science for diagnostic purposes. 相似文献
56.
PURPOSE: This article describes a vascularized bony window for access to the maxillary sinus and reports the clinical results. PATIENTS AND METHODS: A bony U-shaped window in the anterior sinus wall was pedicled on the surrounding soft tissue and periosteum. After the described sinus was cleared of disease, the window was repositioned in its original site either using resorbable sutures or not. The method was used in 47 maxillary sinus operations in 45 patients. Twenty-four patients were followed-up for more than 48 months. RESULTS: The vascularized bony window technique showed uneventful healing in all patients and none of the 24 patients reported any problems. CONCLUSIONS: The vascularized bony window technique provides a large antrostomy, which gives good access and visibility and results in satisfactory postoperative healing. 相似文献
57.
The introduction of resale-based competition in international direct dialing services in January 1999 triggered a round of extremely fierce competition in Hong Kong's IDD market. In response, both the incumbent operator and new entrants had to adopt aggressive strategies to defend or gain market share. This article reports on an intensive experiment on IDD quality provided by the major IDD operators in Hong Kong after this phase of deregulation. Based on 1790 successful IDD calls to the 10 most popular destinations from Hong Kong, the IDD quality of the major operators was benchmarked. The experiment revealed some interesting findings with significant implications for telecommunications deregulation 相似文献
58.
Rau E. I. Gostev A. V. Shiqiu Zhu Phang D. Chan D. Thong D. Wong W. 《Russian Microelectronics》2001,30(4):207-218
The potentialities of three techniques for detecting signals from barrier structures in a scanning electron microscope are discussed. All the methods are virtually contactless; that is, it is only required that the chips are grounded. The relaxation behavior of the signals is considered. The invalidity of the thermoacoustic detection technique is shown. It is experimentally demonstrated that information extracted with the method of electron-beam-induced surface potential is identical to that obtained by thermoacoustic detection. 相似文献
59.
Jee Weng Tan Kwai Lin Thong Nirmala Devi Arumugam Wai Lian Cheah Yih Wei Lai Kek Heng Chua Raha Abdul Rahim Sabaratnam Vikineswary 《International Journal of Hydrogen Energy》2009,34(17):7538-7541
Molybdenum (Mo) nitrogenases consist of two components: dinitrogenase reductase (encoded by nifH) and the dinitrogenase or MoFe protein (encoded by nifDK). Nitrogenase enzyme of photosynthetic bacteria is responsible for hydrogen production. Therefore, primers were designed for the nitrogenase gene only. In this study, two primers (ND and NH) were designed after comparative genomic analysis of nifH and nifD gene sequences from public databases. The designed primers were used for the amplification of nifH and nifD genes to detect nitrogenase genes in photosynthetic bacteria. Initial detection was done using a monoplex Polymerase Chain Reactions (PCRs) followed by optimization of the PCR protocols. Subsequently, a duplex PCR was designed for amplification and detection of nifH and nifD genes in indigenous photosynthetic bacteria. Evaluation of the duplex PCR on six samples isolated from Palm Oil Mill Effluent (POME) showed that only four isolates contained both the nifH and nifD genes, indicating that these isolates were potential hydrogen-producing bacteria. PCR detection provides a rapid and efficient pre-identification of potential photosynthetic bacterial hydrogen producers. 相似文献