首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   366篇
  免费   0篇
电工技术   2篇
化学工业   46篇
金属工艺   3篇
机械仪表   3篇
建筑科学   9篇
矿业工程   1篇
能源动力   3篇
轻工业   85篇
水利工程   4篇
石油天然气   3篇
无线电   17篇
一般工业技术   45篇
冶金工业   117篇
原子能技术   1篇
自动化技术   27篇
  2023年   3篇
  2022年   2篇
  2021年   4篇
  2020年   2篇
  2018年   2篇
  2016年   5篇
  2015年   4篇
  2014年   6篇
  2013年   11篇
  2012年   9篇
  2011年   11篇
  2010年   16篇
  2009年   5篇
  2008年   9篇
  2007年   9篇
  2006年   14篇
  2005年   16篇
  2004年   9篇
  2003年   10篇
  2002年   9篇
  2001年   5篇
  2000年   10篇
  1999年   9篇
  1998年   32篇
  1997年   20篇
  1996年   16篇
  1995年   15篇
  1994年   4篇
  1993年   2篇
  1991年   7篇
  1990年   7篇
  1989年   11篇
  1988年   4篇
  1987年   3篇
  1986年   8篇
  1985年   10篇
  1984年   6篇
  1983年   3篇
  1982年   3篇
  1981年   5篇
  1977年   3篇
  1976年   3篇
  1975年   2篇
  1974年   3篇
  1971年   3篇
  1958年   1篇
  1957年   1篇
  1939年   1篇
  1934年   1篇
  1927年   1篇
排序方式: 共有366条查询结果,搜索用时 15 毫秒
1.
This article examines the usefulness ofvocabulary richness for authorship attributionand tests the assumption that appropriatemeasures of vocabulary richness can capture anauthor's distinctive style or identity. Afterbriefly discussing perceived and actualvocabulary richness, I show that doubling andcombining texts affects some measures incomputationally predictable but conceptuallysurprising ways. I discuss some theoretical andempirical problems with some measures anddevelop simple methods to test how wellvocabulary richness distinguishes texts bydifferent authors. These methods show thatvocabulary richness is ineffective for largegroups of texts because of the extremevariability within and among them. I concludethat vocabulary richness is of marginal valuein stylistic and authorship studies because thebasic assumption that it constitutes awordprint for authors is false.  相似文献   
2.
A 28 mW/MHz at 80 MHz structured-custom RISC microprocessor design is described. This 32-b implementation of the PowerPC architecture is fabricated in a 3.3 V, 0.5 μm, 4-level metal CMOS technology, resulting in 1.6 million transistors in a 7.4 mm by 11.5 mm chip size. Dual 8-kilobyte instruction and data caches coupled to a high performance 32/64-b system bus and separate execution units (float, integer, loadstore, and system units) result in peak instruction rates of three instructions per clock cycle. Low-power design techniques are used throughout the entire design, including dynamically powered down execution units. Typical power dissipation is kept under 2.2 W at 80 MHz. Three distinct levels of software-programmable, static, low-power operation-for system power management are offered, resulting in standby power dissipation from 2 mW to 350 mW. CPU to bus clock ratios of 1×, 2×, 3×, and 4× are implemented to allow control of system power while maintaining processor performance. As a result, workstation level performance is packed into a low-power, low-cost design ideal for notebooks and desktop computers  相似文献   
3.
Viral RNA load has been shown to indicate disease stage and predict the rapidity of disease progression in human immunodeficiency virus type 1 (HIV-1)-infected individuals. We had previously demonstrated that feline immunodeficiency virus (FIV) RNA levels in plasma correlate with disease stage in infected cats. Here we expand upon those observations by demonstrating that plasma virus load is 1 to 2 logs higher in cats with rapidly progressive FIV disease than in long-term survivors. Differences in plasma FIV RNA levels are evident by 1 to 2 weeks after infection and are consistent throughout infection. We also evaluated humoral immune responses in FIV-infected cats for correlation with survival times. Total anti-FIV antibody titers did not differ between cats with rapidly progressive FIV disease and long-term survivors. These findings indicate that virus replication plays an important role in FIV disease progression, as it does in HIV-1 disease progression. The parallels in virus loads and disease progressions between HIV-1 and FIV support the idea that the accelerated disease model is well suited for the study of therapeutic agents directed at reducing lentiviral replication.  相似文献   
4.
5.
6.
Hoover HL 《Applied optics》1986,25(3):359-368
Photochemical damage of ocular tissues by solar radiation depends on the spectral composition of the radiation in the environment, the geometry of the coupling of that radiation to the eye, the spectral transmittances of the ocular components and any auxiliary lenses used, the spectral sensitivity of the irradiated tissue, the accumulated exposure dose, and the action of repair processes. This paper provides formulas for quantitative estimation of corneal, lenticular, and retinal UV irradiances from the sunlit environment under clear sky conditions. Applications of these formulas for ocular irradiation will be presented in subsequent papers for the cornea, lens, and retina, and the results will be evaluated using weighting functions for the sensitivity of ocular tissue.  相似文献   
7.
A technique is described for ensemble-averaging the light wave emerging from a turbid medium, enabling the recovery of optical information that is otherwise lost in a speckle pattern. The technique recovers both an amplitude and a phase function for a wave that has been corrupted by severe scattering, without the use of holography. With the phase estimated, an ensemble-averaged field is constructed that can be backprojected to form an image of the object obscured by the scattering medium. Experimental results suggest that the technique can resolve two object points whose signals are unresolved on the exit surface of a diffuser.  相似文献   
8.
LiMn2-x ErxO4 (x ≤ 0.02) materials were synthesized by a rheological phase reaction method. The thermal behavior of the materials was examined by thermogravimetric and differential scanning calorimetry. X-ray diffraction showed that the samples (x ≤ 0.02 ) exhibited the same phase as the pure spinel. The lattice parameter of the Er-doped spinel was smaller than that of the undoped one and decreased with increasing doping level. Cyclic voltammograms showed two reversible processes corresponding to the typical response of spinel LiMn2O4 and revealed an insertion-extraction reaction occurring at two stages in the 4-V region. The electrochemical performances of the samples were studied and displayed a better reversibility and cyclability.__________From Neorganicheskie Materialy, Vol. 41, No. 6, 2005, pp. 740–743.Original English Text Copyright © 2005 by Haowen Liu, Li Song, Kelli Zhang.This article was submitted by the authors in English.  相似文献   
9.
Computer vision has historically been taught as a graduate subject since few examples of the discipline were being practiced in mainstream engineering. In recent years, the incorporation of multimedia into embedded devices has drawn some vision topics into mainstream attention. Examples of consumer products include digital video recorders, cellular phones, and automobile collision-avoidance systems. This paper describes the development of an undergraduate course that incorporates some vision topics into the larger context of embedded computing. Traditional topics, such as processor types, dynamic power management, and real-time scheduling, are taught alongside relevant vision topics, such as codecs, concurrent interfaces, and multimedia signal acquisition, storage, and rendering. In lab work, the students program hardware to operate as a digital video camera. While the primary goal for the course is to teach embedded computing, a secondary goal for the course is to entice students into graduate study in computer vision. However, a major developmental point was to justify the vision content in the context of how it serves the needs of students not opting for graduate study, as well as how the course would impact students working in other related graduate research areas.  相似文献   
10.
The Swelling Power (SP), Water Binding Capacity (WBC) and rate of rehydration of Add-Back (A–B) and Freeze-Thaw (F–T) potato granules treated with 0.2% monoglyceride decreased during the initial 14 weeks of storage by an average of 25.5 (F–T) and 27.3% (A–B) at 4°C and by 11.1 (F–T) and 12.0% (A–B) at 25°C. However, the moisture content showed an opposite trend, increasing by 5.9 (F–T) and 7.5% (A–B) at 4°C and by 3.6 (F–T) and 4.9% (A–B) at 25°C. Storage beyond 14 weeks at 4°C resulted in increases in SP, WBC and rate of rehydration and decreases in moisture content. However, such a trend was not observed at 25°C. The percentage decreases in SP (during the initial 14 weeks) of treated granules (A–B and F–T) were lower than those of untreated granules by an average of 11.0% at 4°C and 10.5% at 25°C. The extent of starch matrix-cell wall separation and the intensity of the “V” diffraction pattern of an X-ray analysis increased during storage, with greater increases being found at 4°C.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号