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   153篇
  免费   1篇
  国内免费   1篇
电工技术   2篇
化学工业   43篇
金属工艺   1篇
机械仪表   2篇
建筑科学   7篇
矿业工程   4篇
能源动力   3篇
轻工业   14篇
水利工程   1篇
无线电   17篇
一般工业技术   16篇
冶金工业   16篇
原子能技术   3篇
自动化技术   26篇
  2024年   2篇
  2023年   5篇
  2022年   1篇
  2021年   3篇
  2020年   1篇
  2019年   2篇
  2018年   2篇
  2017年   1篇
  2016年   1篇
  2015年   1篇
  2014年   2篇
  2013年   3篇
  2012年   16篇
  2011年   14篇
  2010年   9篇
  2009年   10篇
  2008年   5篇
  2007年   7篇
  2006年   3篇
  2005年   6篇
  2004年   12篇
  2003年   4篇
  2002年   2篇
  2000年   6篇
  1999年   1篇
  1998年   1篇
  1997年   6篇
  1996年   8篇
  1995年   4篇
  1994年   3篇
  1993年   1篇
  1991年   3篇
  1990年   1篇
  1988年   1篇
  1985年   1篇
  1982年   1篇
  1981年   1篇
  1980年   2篇
  1977年   1篇
  1976年   1篇
  1964年   1篇
排序方式: 共有155条查询结果,搜索用时 15 毫秒
141.
Marketing research and corporate planning are enhanced by an effective decision support system. A system developed and implemented in an insurance company is used to illustrate how computer cartography and statistical procedures can be combined as powerful analytical tools. It also demonstrates how a nonprocedural language (SAS with SASGRAPH) can be used to create modules of systems that are efficiently implemented and easily maintained by analysts with limited programming capabilities.  相似文献   
142.
143.
Results of experiments intended to reproduce cold fusion phenomena originally reported by Fleischmann, Pons, and Hawkins are presented. These experiments were performed on a pair of matched electrochemical cells containing 0.1×9 cm Pd rods that were operated for 10 days. The cells were analyzed by the following means: (1) constant temperature calorimetry, (2) neutron counting and γ-ray spectroscopy, (3) mass spectral analysis of4He in effluent gases, and4He and3He within the Pd metal, (4) tritium analysis of the electrolyte solution, and (5) x-ray photoelectron spectroscopy of the Pd cathode surface. Within estimated levels of accuracy, no excess power output or any other evidence of fusion products was detected.  相似文献   
144.
Measurements are presented of the time resolved flux of metallic impurities to a carbon probe placed at the limiter radius of the DITE tokamak. Average fluxes of titanium and molybdenum of the order 4 × 1012 mm?2 s?1 are measured. It is concluded that peaks in the metal flux are correlated with arcing and with disruptions initiated by neutral beam injection. The decrease in flux by almost one order of magnitude compared with earlier studies may be related to a recent redesign of the molybdenum limiters which reduces the minor radius of the plasma. It is observed that the deposit density on the probe is not a linear function of exposure to the plasma and also that insertion of the probe causes a change to the local plasma environment.  相似文献   
145.
146.
Electron accelerators are being widely used in industry to process polymeric materials. Their use to cure fiber-reinforced composites is an emerging technology, based on the work done here in Canada, and in France. The advantages of electron curing include ambient temperature curing with reduced internal stress, reduced curing times, and overall cost of savings. In this paper we present a brief review of our work with emphasis on the effects of dose and dose rate, temperature rise during curing, internal stress, voids, properties of matrix resins and a comparison of the properties of electron cured and thermally cured matrices and composites.Abbreviations: kW kilo-watt - eV electron volt - RTM resin transfer molding - SEC size exclusion chromatography - Gy Gray (1 Gy = 100 rad) - THF tetrahydrofuran - AMU atomic mass unit - T g glass transition temperature  相似文献   
147.
Endometrial lymphomyeloid cell subsets were evaluated in samples from normal women and from women with abnormal uterine bleeding due to subcutaneous levonorgestrel implants (Norplant) or an intrauterine device (IUD). The frequency of CD3(+), CD68(+), CD43(+) and endometrial granulated lymphoid cells was evaluated by immunohistochemical or phloxine-tartrazine staining of formalin-fixed paraffin-embedded samples. In normal women, cyclic variation in lymphomyeloid subsets was seen. In women using Norplant for contraception, the frequency of CD3(+), CD68(+) and CD43(+) cells was dramatically decreased, compatible with endometrial atrophy. When Norplant users with abnormal bleeding were compared to women without bleeding, however, the number of CD68(+) cells was significantly increased and the number of CD3(+) and CD43(+) cells was preserved, contrary to the hypothesis that this group would show a greater degree of atrophy and hence, tissue fragility. A similar pattern was seen in a preliminary study of women with bleeding associated with use of copper-only IUD contraception, and in samples taken from late secretory and menstrual biopsies from normal cycling women. Whether these changes in endometrial lymphomyeloid cells represent a result of bleeding arising from a common mechanism or rather cause the uterine bleeding is discussed.  相似文献   
148.
Soybean breeding programs underway today are addressing the goal of improving the protein profile to benefit the human diet as well as that of livestock. Glycinin, a globulin storage protein of the meal and designated as the 11S size fraction by ultracentrifugation, is desirable because of its relative abundance of sulfur-containing amino acids, such as methionine and cysteine. The current study examined the feasibility of near-infrared (NIR) measurement of glycinin and the other prevalent protein fraction, β-conglycinin (7S size fraction), as well as the electrophoretically separable sub fractions that comprise these two components. From a population of 101 F6-derived recombinant inbred lines in a field replicated trial, single whole soybeans were scanned in transmittance (800–1,798 nm, 24 beans/sample × 197 samples total). Additional scanning of the ground meal was performed in reflectance (1,100–2,498 nm). Partial least squares (PLS) calibrations were developed, using the 24-bean average log(1/T) spectrum for each sample, as well as the average spectrum from duplicate packs of log(1/R) spectra of the meal. The results indicate that NIR prediction of 11S and 7S, as well as the sub fractions thereof, is at best limited to screening purposes in soybean breeding programs for probable reasons of an inherent lack of spectral specificity of the protein fractions and a non-constant proportion of soluble-to-total protein.
Dilip R. Panthee
  相似文献   
149.
150.
Well-dispersed Rh(OH)3 nanoparticles were deposited in the interlayer galleries of a Dion-Jacobson type layered perovskite (ACa2Nb3O10: A=H or K). X-ray photoelectron spectra and zeta potential measurements suggest covalent bonding (Rh-O-Nb) between the nanoparticles and the niobate sheets. After calcination of Rh(OH)3/KCa2Nb3O10 at 350 degrees C in air, interlayer Rh(OH)3 nanoparticles were transformed to Rh2O3 and showed higher photocatalytic activity for hydrogen evolution using methanol as a sacrificial electron donor.  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