全文获取类型
收费全文 | 4280篇 |
免费 | 401篇 |
国内免费 | 27篇 |
专业分类
电工技术 | 80篇 |
综合类 | 33篇 |
化学工业 | 1004篇 |
金属工艺 | 120篇 |
机械仪表 | 315篇 |
建筑科学 | 108篇 |
矿业工程 | 5篇 |
能源动力 | 194篇 |
轻工业 | 367篇 |
水利工程 | 17篇 |
石油天然气 | 16篇 |
无线电 | 739篇 |
一般工业技术 | 909篇 |
冶金工业 | 287篇 |
原子能技术 | 69篇 |
自动化技术 | 445篇 |
出版年
2024年 | 3篇 |
2023年 | 52篇 |
2022年 | 55篇 |
2021年 | 166篇 |
2020年 | 100篇 |
2019年 | 141篇 |
2018年 | 142篇 |
2017年 | 173篇 |
2016年 | 192篇 |
2015年 | 164篇 |
2014年 | 207篇 |
2013年 | 255篇 |
2012年 | 305篇 |
2011年 | 361篇 |
2010年 | 262篇 |
2009年 | 240篇 |
2008年 | 243篇 |
2007年 | 175篇 |
2006年 | 158篇 |
2005年 | 122篇 |
2004年 | 130篇 |
2003年 | 122篇 |
2002年 | 124篇 |
2001年 | 102篇 |
2000年 | 89篇 |
1999年 | 78篇 |
1998年 | 114篇 |
1997年 | 86篇 |
1996年 | 65篇 |
1995年 | 50篇 |
1994年 | 42篇 |
1993年 | 20篇 |
1992年 | 37篇 |
1991年 | 23篇 |
1990年 | 10篇 |
1989年 | 19篇 |
1988年 | 10篇 |
1987年 | 16篇 |
1986年 | 7篇 |
1985年 | 6篇 |
1984年 | 6篇 |
1983年 | 7篇 |
1982年 | 3篇 |
1980年 | 4篇 |
1979年 | 4篇 |
1978年 | 2篇 |
1977年 | 3篇 |
1976年 | 9篇 |
1972年 | 1篇 |
1914年 | 2篇 |
排序方式: 共有4708条查询结果,搜索用时 31 毫秒
11.
Anna Hać 《Journal of Network and Systems Management》1994,2(1):49-62
This paper analyzes the performance of a switching architecture. The performance measures include the elapsed time of packet transfer and the waiting time to begin transfer. The architecture is partitioned depending on the type of network used and the expected traffic in the network. Every partition has a switch with a buffer that can absorb surges of bursty traffic within the network partition. The buffer size depends on the type of the network and incoming traffic. The partition size depends on the network bandwidth, network traffic, packet size and buffer size. Examples of different networks are used to show the applications of the model. The results show that the elapsed time of packet switch transfer depends exponentially on the number of partitions in the network. 相似文献
12.
Seong-Ku Kim Joon Kyu Lee Yong-Mo Kim Jae-Hyun Ahn 《Journal of Mechanical Science and Technology》2002,16(7):1009-1018
The Representative Interactive Flamelet (RIF) concept has been applied to numerically simulate the combustion processes and
pollutant formation in the direct injection diesel engine. Due to the ability for interactively describing the transient behaviors
of local flame structures with CFD solver, the RIF concept has the capabilities to predict the auto-ignition and subsequent
flame propagation in the diesel engine combustion chamber as well as to effectively account for the detailed mechanisms of
soot formation, NOX formation including thermal NO path, prompt and nitrous NOX formation, and reburning process. Special emphasis is given to the turbulent combustion model which properly accounts for
vaporization effects on the mixture fraction fluctuations and the pdf model. The results of numerical modeling using the RIF
concept are compared with experimental data and with numerical results of the commonly applied procedure which the low-temperature
and high-temperature oxidation processes are represented by the Shell ignition model and the eddy dissipation model, respectively.
Numerical results indicate that the RIF approach including the vaporization effect on turbulent spray combustion process successfully
predicts the ignition delay time and location as well as the pollutant formation. 相似文献
13.
Seung-Jean Kim In-Joong Ha 《Automatic Control, IEEE Transactions on》2004,49(7):1167-1171
In this note, we consider the existence of a Carathe/spl acute/odory solution in a single-input-single-output nonlinear system with a discontinuous switching feedback controller. The main contribution is to show that if the nonlinear system can be transformed into a global normal form, then we can specify the value of the discontinuous switching feedback controller on the switching hypersurface so that the closed-loop system has a Carathe/spl acute/odory solution. 相似文献
14.
Transglutaminase (TGase), responsible for crosslinking between proteins, is known to be localized exclusively in the egg envelope (chorion) of rainbow trout, Oncorhynchus mykiss, and probably participates in the post-fertilization chorion hardening. We purified the TGase from unfertilized egg chorions by sequential chromatography using SP-Sepharose, Q-Sepharose, and TSK-gel G3000SWXL columns. The purified enzyme was a monomeric protein having the molecular mass of 76 kDa. It promoted incorporation of monodansyl-cadaverine into chorion protein and catalyzed the polymerization of chorion subunit proteins. The effect of various reagents suggested that the chorion TGase is a Ca2+-dependent SH-enzyme similar to the well-characterized TGases of various animals. The highest activity was observed at pH 6.0. The amines examined in the present study inhibited the TGase activity of the purified enzyme. However, they did not necessarily cause effective inhibition of its activity. These properties of the chorion TGase were essentially consistent with our previous observations on polymerization of chorion proteins, resulting in chorion hardening. We compared the amino acid composition of the purified TGase with those of the previously characterized TGases of fishes, such as chum salmon and red sea bream. The results suggest that the chorion 76 kDa TGase is not homologous with those liver TGases in terms of amino acid composition. 相似文献
15.
HJ Lee HK Ha MH Kim YK Jeong PN Kim MG Lee JS Kim DJ Suh SG Lee YI Min YH Auh 《Canadian Metallurgical Quarterly》1997,169(2):517-520
OBJECTIVE: The purpose of this study was to evaluate ERCP and CT findings of ectopic drainage of the common bile duct into the duodenal bulb. CONCLUSION: Although rare, the diagnosis of ectopic drainage of the common bile duct into the duodenal bulb is important to prevent inadvertent damage during biliary tract or gastric surgery and to clarify the cause of chronic peptic ulcers. 相似文献
16.
The crystal structure of Escherichia coli ornithine transcarbamoylase (OTCase, EC 2.1.3.3) complexed with the bisubstrate analog N-(phosphonacetyl)-L-ornithine (PALO) has been determined at 2.8-A resolution. This research on the structure of a transcarbamoylase catalytic trimer with a substrate analog bound provides new insights into the linkages between substrate binding, protein-protein interactions, and conformational change. The structure was solved by molecular replacement with the Pseudomonas aeruginosa catabolic OTCase catalytic trimer (Villeret, V., Tricot, C., Stalon, V. & Dideberg, O. (1995) Proc. Natl. Acad. Sci. USA 92, 10762-10766; Protein Data Bank reference pdb 1otc) as the model and refined to a crystallographic R value of 21.3%. Each polypeptide chain folds into two domains, a carbamoyl phosphate binding domain and an L-ornithine binding domain. The bound inhibitor interacts with the side chains and/or backbone atoms of Lys-53, Ser-55, Thr-56, Arg-57, Thr-58, Arg-106, His-133, Asn-167, Asp-231, Met-236, Leu-274, Arg-319 as well as Gln-82 and Lys-86 from an adjacent chain. Comparison with the unligated P. aeruginosa catabolic OTCase structure indicates that binding of the substrate analog results in closure of the two domains of each chain. As in E. coli aspartate transcarbamoylase, the 240s loop undergoes the largest conformational change upon substrate binding. The clinical implications for human OTCase deficiency are discussed. 相似文献
17.
18.
Joon C. Park Author Vitae Author Vitae 《Computer aided design》2003,35(9):807-812
Presented in this paper is a topology reconstruction algorithm from a set of unorganized trimmed surfaces. Error-prone small geometric elements are handled to give proper topological information. It gives complete topology to topologically complete models, and it is also tolerant to incomplete models. The proposed algorithm is vertex-based in that clues for topological information are searched from the set of vertices first, not from that of edges. 相似文献
19.
Corrosion rates were measured at the exposed spots of rebars near three corners of Muddy Creek Bridge located in northern West Virginia using a 3LP device. Also, chloride contents of the concrete samples taken from the vicinity of the spots were analyzed using a wet chemical method that had been developed in this study. The average corrosion rate over the three spots was 4.66 mA/m2, which is in the range of corrosion damage possible in 10–15 years. The average chloride content of the concrete over the three spots was 703 parts per million (ppm), which is well above the threshold limit value of 260 ppm. Although the corrosion rate measurement method using a 3LP device is by manual operation, it is found to be reliable and effective, and, thus, recommended for future studies of this kind of research. The wet chemical method developed in this study is found to be effective. 相似文献
20.
Novel floating-patch micro-electro-mechanical system (MEMS) antennas are proposed for millimetre-wave applications. The floating-patch MEMS antennas are fabricated on a high resistivity silicon (HRS) substrate using surface micromachining technology. Simulation and experimental results for reflection coefficients and radiation patterns are presented. 相似文献