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   533篇
  免费   5篇
电工技术   6篇
化学工业   108篇
金属工艺   6篇
机械仪表   10篇
建筑科学   11篇
矿业工程   1篇
能源动力   11篇
轻工业   25篇
石油天然气   4篇
无线电   29篇
一般工业技术   64篇
冶金工业   225篇
原子能技术   8篇
自动化技术   30篇
  2022年   5篇
  2021年   6篇
  2013年   21篇
  2012年   6篇
  2011年   17篇
  2010年   8篇
  2009年   16篇
  2008年   10篇
  2007年   8篇
  2006年   8篇
  2005年   13篇
  2004年   5篇
  2003年   10篇
  2002年   6篇
  2001年   7篇
  2000年   7篇
  1999年   7篇
  1998年   24篇
  1997年   13篇
  1996年   16篇
  1995年   9篇
  1994年   12篇
  1993年   12篇
  1992年   11篇
  1990年   4篇
  1989年   9篇
  1988年   7篇
  1987年   13篇
  1986年   13篇
  1985年   14篇
  1984年   14篇
  1983年   10篇
  1982年   6篇
  1981年   8篇
  1980年   6篇
  1979年   14篇
  1978年   14篇
  1977年   14篇
  1976年   12篇
  1975年   12篇
  1974年   6篇
  1973年   7篇
  1972年   7篇
  1971年   4篇
  1970年   5篇
  1968年   7篇
  1967年   4篇
  1966年   6篇
  1958年   6篇
  1955年   4篇
排序方式: 共有538条查询结果,搜索用时 281 毫秒
61.
Four experiments used a 4-choice discrimination learning paradigm to explore the pigeon's recognition of line drawings of 4 objects (an airplane, a chair, a desk lamp, and a flashlight) that were rotated in depth. The pigeons reliably generalized discriminative responding to pictorial stimuli over all untrained depth rotations, despite the birds' having been trained at only a single depth orientation. These generalization gradients closely resembled those found in prior research that used other stimulus dimensions. Increasing the number of different vantage points in the training set from 1 to 3 broadened the range of generalized testing performance, with wider spacing of the training orientations more effectively broadening generalized responding. Template and geon theories of visual recognition are applied to these empirical results. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
62.
The effect of the host system on the pathogenicity, immunogenicity, and antigenicity of infectious bursal disease virus (IBDV) was investigated. One classic (SAL) and one variant strain (IN) of IBDV were passaged separately six times in three host systems, namely BGM-70 continuous cell line, primary chicken embryo fibroblast (CEF) cells, or embryonating chicken eggs (embryos) or one time in the bursa of Fabricius (BF) of specific-pathogen-free (SPF) chickens. Passage in BGM-70 cells or CEF cells resulted in loss of pathogenicity, but viruses passaged in embryos or BF maintained their pathogenicity. For the immunogenicity study, the viruses described above were used to prepare live and inactivated vaccines, containing 10(3) mean embryo infectious doses (EID50s) and 10(5) EID50s respectively. These vaccines induced different levels of protection. It was concluded that the antigen titration methodology employing embryonating chicken eggs was not suitable for titration of viruses propagated in other host systems because of varying degrees of adaptation and/or pathogenicity of the viruses resulting in variability in antigen mass of the tested vaccines. To test this assumption, an antigen-capture enzyme-linked immunosorbent assay was used as a titration system to compare the antigenicity of viruses propagated in BGM-70 cells or BF. Preparations containing similar antigen masses were inactivated then inoculated into two age groups of SPF chickens and antibody titers were monitored. During the experimental period, the geometric mean virus-neutralizing (VN) antibody titers of the vaccinated groups did not differ significantly (P > 0.05).  相似文献   
63.
Combined data from a study by J. R. Council et al (see record 1983-24975-001) and from a study by the present 3rd author (1983) on cognitive skill hypnotic induction to test the hypothesis that the relationship between expectancy and suggestibility varies as a function of type of induction. Analysis of data on 100 Ss shows significant Expectancy?×?Type of Induction interactions on the Stanford Hypnotic Susceptibility Scale, the Creative Imagination Scale, and an inventory of hypnotic depth. Within-cells correlations revealed a significant relationship between expectancy and responses to skill induction. Correlations between expectancy and responses to a traditional trance induction were nonsignificant. (8 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
64.
Three new cases of congenital segmental dilatation of the ileum are presented and added to 12 cases of segmental dilatation found in the literature. The aspect of the condition which is of particular interest is the presence in 3 of the dilated segments of heteroplastic foregut derivatives of unusual varieties. The etiology of the condition is discussed; it does not appear to be a single distinct pathological entity.  相似文献   
65.
66.
67.
Models useful in the dynamic method for KLa measurements are developed and compared. Particular attention is given to the gas phase dynamics and the oxygen electrode response time. Comparisons and error calculations are based on computer simulations. Correction factors are presented for a range of dimensionless parameters. In general, the errors resulting from neglecting the gas phase dynamics and the electrode response can be expected to be large.  相似文献   
68.
For good reasons, there has been a spate of articles, much thinking, and a fair amount of industrial action on making chemicals and fuels from methanol, Only methane and methanol are made commercially in over 99% yields from synthesis gas.  相似文献   
69.
Title of program: EFFECTIVE REGGE TRAJECTORIES Catalogue number: ABCE Program obtainable from: CPC Program Library, Queen's University of Belfast, N. Ireland (see application form in this issue). Computer: IBM 360/67; Installation: Northumbrian Universities Multiple Access Computer, Durham, UK Operating system or monitor under which the program is executed: MICHIGAN TERMINAL SYSTEM Programming language used: FORTRAN IV High speed storage required: 46K words. No. of bits in a word: 32 Is the program overlaid? No No. of magnetic tapes required: None What other peripherals are used? Card Reader; Line Printer No. of cards in combined program and test deck: 1381 Card punching code: EBCDIC  相似文献   
70.
The flavonol glycosides, quercetin-3-glucoglucoside and kaempferol-3-rhamnoglucoside, have been separated from crushed, delinted cottonseed (kernel and hull) by extensive use of paper chromatography, ultraviolet spectrophotometry, and qualitative and quantitative analysis of their hydrolysis products. Details of the separation and identification are described. Aided by a Fellowship from the National Medical Fellowship Inc. through funds appropriated by the National Foundation for Infantile Paralysis.  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