全文获取类型
收费全文 | 447篇 |
免费 | 9篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 10篇 |
化学工业 | 100篇 |
金属工艺 | 11篇 |
机械仪表 | 16篇 |
建筑科学 | 19篇 |
矿业工程 | 1篇 |
能源动力 | 16篇 |
轻工业 | 69篇 |
水利工程 | 1篇 |
石油天然气 | 2篇 |
无线电 | 25篇 |
一般工业技术 | 60篇 |
冶金工业 | 73篇 |
自动化技术 | 55篇 |
出版年
2023年 | 4篇 |
2022年 | 8篇 |
2021年 | 6篇 |
2020年 | 6篇 |
2019年 | 8篇 |
2018年 | 7篇 |
2016年 | 9篇 |
2014年 | 7篇 |
2013年 | 14篇 |
2012年 | 19篇 |
2011年 | 18篇 |
2010年 | 25篇 |
2009年 | 12篇 |
2008年 | 14篇 |
2007年 | 12篇 |
2006年 | 18篇 |
2005年 | 12篇 |
2004年 | 12篇 |
2003年 | 8篇 |
2002年 | 6篇 |
2001年 | 8篇 |
2000年 | 8篇 |
1999年 | 7篇 |
1998年 | 16篇 |
1997年 | 15篇 |
1996年 | 11篇 |
1995年 | 8篇 |
1994年 | 7篇 |
1993年 | 5篇 |
1992年 | 6篇 |
1991年 | 6篇 |
1989年 | 4篇 |
1988年 | 4篇 |
1986年 | 9篇 |
1985年 | 12篇 |
1984年 | 12篇 |
1983年 | 5篇 |
1982年 | 6篇 |
1981年 | 9篇 |
1980年 | 5篇 |
1978年 | 4篇 |
1977年 | 6篇 |
1976年 | 6篇 |
1974年 | 4篇 |
1973年 | 3篇 |
1971年 | 6篇 |
1970年 | 4篇 |
1969年 | 3篇 |
1968年 | 3篇 |
1919年 | 3篇 |
排序方式: 共有458条查询结果,搜索用时 15 毫秒
1.
2.
Ferdinand P. Ferragu O. Lechien J.L. Lescop B. Magne S. Marty V. Rougeault S. Kotrotsios G. Neuman V. Depeursinge Y. Michel J.B. Van Uffelen M. Varelas D. Berthou H. Pierre G. Renouf C. Jarret B. Verbandt Y. Stevens W. Voet M.R.H. Toscano D. 《Lightwave Technology, Journal of》1995,13(7):1303-1313
Recent developments of stability control in mines, essentially based on Ge-doped fiber Bragg gratings (FBG) are reported including results about the different aspects of the system: accurate characterizations of FBG, sensor network topology and multiplexing method, user interface design and sensor packaging 相似文献
3.
Two-dimensional map of Haemophilus influenzae following protein enrichment by heparin chromatography
M Fountoulakis H Langen S Evers C Gray B Takács 《Canadian Metallurgical Quarterly》1997,18(7):1193-1202
Two-dimensional gel electrophoresis separates several hundred protein molecules in one single experiment and is efficiently used to study the products expressed by different genomes. Low-copy-number gene products are invisible on a stained two-dimensional map and must be enriched such that sufficient amounts are present for visualization and identification. We investigated the enrichment of proteins of the bacterium Haemophilus influenzae by chromatography on immobilized heparin which has affinity for growth and protein biosynthesis factors. Total soluble proteins of the microorganism were fractionated on Heparin-Actigel which resulted in enrichment of approximately 160 proteins. The eluates, representing about 40% of the applied proteins, were analyzed by two-dimensional gel electrophoresis and the protein spots were characterized by amino acid composition analysis and matrix-assisted laser desorption ionization mass spectrometry. The proteins enriched by chromatography on the heparin gel were not exclusively low-copy-number gene products and they did not exclusively belong to one single class of proteins. The proteins that bound to the heparin gel are indicated in a two-dimensional protein map which includes more than 110 newly identified proteins. 相似文献
4.
5.
HJ Kim BM Evers NA Banker GH Greeley MR Hellmich JC Thompson CM Townsend 《Canadian Metallurgical Quarterly》1998,43(7):1465-1473
Gastrin-secreting tumors have been identified in ectopic locations including the ovary; the mechanisms regulating gastrin gene expression, its distribution, and signaling pathways in these ectopic tissues are not known. The purpose of our present study was to determine: (1) whether the gastrin gene and peptide could be detected in ovarian cancer cell lines, (2) if functional gastrin releasing peptide receptors (GRP-R) are present, and (3) whether gastrin gene expression is altered by GRP. Five ovarian cancer cell lines (SW626, OVCA 420, OVCA 429, OVCA 432, and OVCA 433) were analyzed. We identified gastrin gene and peptide expression in the SW626 cell line but not in the OVCA lines. SW626 cells express a functional GRP-R that is correctly coupled to the Ca2+ signaling pathway. Treatment of SW626 cells with bombesin, the amphibian equivalent of GRP, inhibited expression of the gastrin gene in a time- and dose-dependent fashion. The SW626 ovarian cancer cell line will provide a useful model to further define regulation and expression of both the gastrin gene and peptide in ectopic (nongastrointestinal) tissues. 相似文献
6.
Integrating products and services to customized solutions can help firms to differentiate from their competitors. In practice, however, various companies fall short in extracting value from their customers. Therefore this paper focuses on pricing aspects as central means for value appropriation in the context of solutions. Following the resource-based view of the firm, we adopt a process-oriented perspective on pricing practices in order to identify crucial factors and activities. Based on 15 in-depth interviews with practitioners from various industries we derive six steps of a price management process for value appropriation in the context of solution selling and present critical activities and routines within each step. 相似文献
7.
8.
9.
Ferdinand Verhulst 《Journal of Engineering Mathematics》2005,53(3-4):349-358
Stable normal-mode vibrations in engineering can be undesirable and one of the possibilities for quenching these is by embedding
the oscillator in an autoparametric system by coupling to a damped oscillator. There exists the possibility of destabilizing
the undesirable vibrations by a suitable tuning and choice of nonlinear coupling parameters. An additional feature is that,
to make the quenching effective in the case of relaxation oscillations, one also has to deform the slow manifold by choosing
appropriate coupling; this is illustrated for Rayleigh and van der Pol relaxation. 相似文献
10.
Elasser A. Kheraluwala M.H. Ghezzo M. Steigerwald R.L. Evers N.A. Kretchmer J. Chow T.P. 《Industry Applications, IEEE Transactions on》2003,39(4):915-921
Recent progress in silicon carbide (SiC) material has made it feasible to build power devices of reasonable current density. This paper presents results including a comparison with state-of-the-art silicon diodes. Switching losses for two silicon diodes (a fast diode, 600 V, 50 A, 60 ns Trr), an ultrafast silicon diode (600 V, 50 A, 23 ns Trr), and a 4H-SiC diode (600 V, 50 A) are compared. The effect of diode reverse recovery on the turn-on losses of a fast insulated gate bipolar transistor (IGBT) are studied both at room temperature and at 150 /spl deg/C. At room temperature, SiC diodes allow a reduction of IGBT turn-on losses by 25% compared to ultrafast silicon diodes and by 70% compared to fast silicon diodes. At 150 /spl deg/C junction temperature, SiC diodes allow turn-on loss reductions of 35% and 85% compared to ultrafast and fast silicon diodes, respectively. The silicon and SiC diodes are used in a boost converter with the IGBT to assess the overall effect of SiC diodes on the converter characteristics. Efficiency measurements at light load (100 W) and full load (500 W) are reported. Although SiC diodes exhibit very low switching losses, their high conduction losses due to the high forward drop dominate the overall losses, hence reducing the overall efficiency. Since this is an ongoing development, it is expected that future prototypes will have improved forward characteristics. 相似文献