全文获取类型
收费全文 | 333篇 |
免费 | 9篇 |
专业分类
电工技术 | 1篇 |
综合类 | 1篇 |
化学工业 | 40篇 |
金属工艺 | 9篇 |
机械仪表 | 4篇 |
建筑科学 | 3篇 |
能源动力 | 8篇 |
轻工业 | 32篇 |
无线电 | 24篇 |
一般工业技术 | 64篇 |
冶金工业 | 116篇 |
原子能技术 | 2篇 |
自动化技术 | 38篇 |
出版年
2023年 | 3篇 |
2022年 | 2篇 |
2021年 | 9篇 |
2020年 | 8篇 |
2019年 | 3篇 |
2018年 | 8篇 |
2017年 | 5篇 |
2016年 | 4篇 |
2015年 | 4篇 |
2014年 | 7篇 |
2013年 | 6篇 |
2012年 | 13篇 |
2011年 | 21篇 |
2010年 | 13篇 |
2009年 | 6篇 |
2008年 | 12篇 |
2007年 | 7篇 |
2006年 | 9篇 |
2005年 | 8篇 |
2004年 | 8篇 |
2003年 | 6篇 |
2002年 | 9篇 |
2001年 | 6篇 |
2000年 | 7篇 |
1999年 | 6篇 |
1998年 | 31篇 |
1997年 | 21篇 |
1996年 | 12篇 |
1995年 | 9篇 |
1994年 | 7篇 |
1993年 | 8篇 |
1992年 | 4篇 |
1991年 | 3篇 |
1990年 | 3篇 |
1988年 | 2篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1983年 | 5篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 3篇 |
1979年 | 5篇 |
1978年 | 2篇 |
1977年 | 10篇 |
1976年 | 10篇 |
1975年 | 4篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1968年 | 1篇 |
1961年 | 2篇 |
排序方式: 共有342条查询结果,搜索用时 31 毫秒
1.
2.
The aim of this work was to determine the principal mechanical parameters of a thin film on a substrate, i.e. Young's modulus, Poisson's ratio, intrinsic stress, and coefficient of linear thermal expansion. First, standard experiments possibly suitable for this purpose were investigated theoretically. The margin of error of the mechanical parameters determined was estimated as dependent on the geometrical conditions, substrate properties, and error in the respective measurements. In addition, the homogeneity and stability of the parameters were taken into account, for instance inhomogeneity of the film thickness and possible modification of substrate parameters during film growth. To obtain meaningful results, the accuracy of the measurements as well as the homogeneity and stability of several geometrical and physical parameters in general must be extremely high. However, the experimental conditions were found to fulfill these requirements. 相似文献
3.
Measurements of variation with pressure of the collective diffusion constant Dc in polyacrylamide gels using both a good solvent (water) and a theta solvent (methanol 30% - water 70% by volume) are reported. From these observations the variation of ξh, the hydrodynamic screening length in the gel, is obtained, and compared with ξst, the static screening length. The latter is obtained from measurements of the density of the polymer solutions. In the concentration range studied (3%–10%) and for pressures up to 3 kbar, both ξh and ξst diminish with increasing pressure (i.e. the solvent quality improves), but the variation of ξh is more than an order of magnitude smaller than ξst for both the poor and good solvent cases. 相似文献
4.
Arylalkynes such as 4-phenyl-1-butyne (PBY), 5-phenyl-1-pentyne (PPY) and 2-ethynylnaphthalene (2-EN) are suicide inhibitors of cytochrome P450 enzymes. Arylalkyl isothiocyanates such as 6-phenylhexyl isothiocyanate (PHITC) are structurally related to arylalkynes and are known to inhibit the cytochrome P450 mediated metabolic activation and tumorigenicity of a tobacco-specific lung carcinogen, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK). In this study, we compared the ability of PBY, PPY, 2-EN and PHITC to inhibit A/J mouse lung tumorigenesis by NNK. Groups of 20 female mice were gavaged with 5 mumol of arylalkyne or PHITC in corn oil. Two hours later they were given a single i.p. injection of 10 mumol NNK. The mice were killed 16 weeks later. PPY and PHITC were both potent inhibitors of tumorigenesis by NNK, reducing lung tumor multiplicity from 8.35 tumors per mouse to 0.40 and 0.35 respectively. PBY and 2-EN also significantly inhibited tumor multiplicity. The results of this study demonstrate that arylalkynes and PHITC are potent inhibitors of NNK induced lung tumorigenesis in A/J mice, consistent with the hypothesis that inhibition of specific cytochrome P450 enzymes is involved in inhibition of tumorigenesis. 相似文献
5.
Ye Yunguang Sun Yu Dongfang Shiping Shi Dachuan Hecht Markus 《Multibody System Dynamics》2021,51(1):91-122
Multibody System Dynamics - The selection of a wheel profile is a topic of great interest as it can affect running performances and wheel wear, which needs to be determined based on the actual... 相似文献
6.
R. A. Brennen M. H. Hecht D. V. Wiberg S. J. Manion W. D. Bonivert J. M. Hruby M. L. Scholz T. D. Stowe T. W. Kenny K. H. Jackson C. K. Malek 《Microsystem Technologies》1997,3(3):91-96
We are fabricating sub-collimating X-ray grids that are to be used in an orbiting solar X-ray telescope. The telescope optics
consist of twelve rotating pairs of high aspect ratio grids. The pitch for the grids ranges from 34 μm to 317 μm. The grid
thickness-to-grid-slit ratio must be approximately 50:1, resulting in grid thicknesses of 1 to 10 millimeters. We are implementing
a design in which a 34 μm pitch, free-standing PMMA grid is fabricated with 20 μm wide slits through a 800 μm thickness. After
exposure and developing, metal is electrodeposited into the slits in the PMMA grid and the PMMA is left in place to hold the
individual metal pieces. For optimum imaging performance, the root-mean-square pitch of the two grids of each pair must match
to within 1 part in 10000 and simultaneous exposures of stacked sheets of PMMA have insured that this requirement is met.
Received: 30 October 1995 / Accepted: 25 January 1996 相似文献
7.
Due to advances in fiber-optics and VLSI technology, interconnection networks that allow multiple simultaneous broadcasts are becoming feasible. Distributed-shared-memory implementations on such networks promise high performance even for applications with small granularity. This paper presents the architecture of one such implementation, called the simultaneous optical multiprocessor exchange bus, and examines the performance of augmented DSM protocols that exploit the natural duplication of data to maintain a recovery memory in each processing node and provide basic fault tolerance. Simulation results show that the additional data duplication necessary to create fault-tolerant DSM causes no reduction in system performance during normal operation and eliminates most of the overhead at checkpoint creation. Under certain conditions, data blocks that are duplicated to maintain the recovery memory are utilized by the underlying DSM protocol, reducing network traffic, and increasing the processor utilization significantly. 相似文献
8.
Hecht Matthew D. Picard Yoosuf N. Webler Bryan A. 《Metallurgical and Materials Transactions A》2017,48(5):2320-2335
Metallurgical and Materials Transactions A - We have examined spheroidization and coarsening of cementite in an initially pearlitic 2C-4Cr ultrahigh carbon steel containing a cementite network.... 相似文献
9.