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   608543篇
  免费   7092篇
  国内免费   1690篇
电工技术   11176篇
综合类   710篇
化学工业   93160篇
金属工艺   25149篇
机械仪表   19133篇
建筑科学   13783篇
矿业工程   3916篇
能源动力   14312篇
轻工业   51592篇
水利工程   6852篇
石油天然气   13396篇
武器工业   115篇
无线电   68860篇
一般工业技术   119004篇
冶金工业   112234篇
原子能技术   14535篇
自动化技术   49398篇
  2021年   5127篇
  2019年   4957篇
  2018年   8551篇
  2017年   8615篇
  2016年   9206篇
  2015年   5738篇
  2014年   9704篇
  2013年   26121篇
  2012年   15410篇
  2011年   20734篇
  2010年   16502篇
  2009年   18408篇
  2008年   19406篇
  2007年   19364篇
  2006年   17261篇
  2005年   15577篇
  2004年   14854篇
  2003年   14513篇
  2002年   14152篇
  2001年   14041篇
  2000年   13456篇
  1999年   13624篇
  1998年   32823篇
  1997年   23227篇
  1996年   18149篇
  1995年   14026篇
  1994年   12447篇
  1993年   12432篇
  1992年   9728篇
  1991年   9159篇
  1990年   9080篇
  1989年   8746篇
  1988年   8512篇
  1987年   7416篇
  1986年   7449篇
  1985年   8509篇
  1984年   8049篇
  1983年   7392篇
  1982年   6914篇
  1981年   7047篇
  1980年   6792篇
  1979年   6649篇
  1978年   6551篇
  1977年   7300篇
  1976年   9043篇
  1975年   5893篇
  1974年   5673篇
  1973年   5892篇
  1972年   4936篇
  1971年   4518篇
排序方式: 共有10000条查询结果,搜索用时 10 毫秒
991.
992.
993.
Salmonella strains exposed to lethal doses of gamma radiation are detoxified but retain their antigenic properties. Using eight Salmonella strains representative of each of the Salmonella serogroups A to G, a polyvalent radiovaccine has been developed which effectively immunizes mice to several Salmonella serotypes.  相似文献   
994.
The chemical composition and nutritional quality of tehineh, a paste of dehulled roasted sesame seeds, from Saudi Arabia and other countries, were studied. Results showed 24.7% protein, 58.9% fat, 2.3% fiber, 3.0% ash and <1.0% moisture. The tehineh contained relatively high amounts (mg/100 g) of P (692), Mg (362), Fe (7.19), Cu (1.96), Mn (1.46) and Zn (7.82) and low amounts of Ca (61) and Se (0.05). Gas-liquid chromatography (GLC) analysis of the oil revealed percentages of 42.4 for oleic, 39.7 for linoleic, 9.8 for palmitic and 6.4 for stearic acid. Lysine was the only limiting amino acid with a chemical score of 64, while the sulphur-containing amino acids (methionine + cystine) and tryptophan were present in amounts exceeding the requirement of the FAO/WHO (1973) reference protein. The in vitro protein digestibility (IVPD) value of 83.3% and the calculated protein efficiency ratio (C-PER), 2.14, were slightly higher than those of sesame seeds and both values were lower than the IVPD and C-PER of 90.0% and 2.50, respectively, for ANRC casein.  相似文献   
995.
The secondary effluent from municipal plants in Korea generally represents higher BOD with lower SS. Therefore, more soluble forms of organics and NH4-N need to be removed to improve its effluent for reuse. In this study reuse possibility of secondary effluent and CSO (combined sewer overflow) using BAF (biological aerated filter) was evaluated. The tertiary application with 1.2 h EBCT, SS, BOD and COD showed stable concentrations less than 1.3, 1.3 and 6.2 mg/L, respectively. Nitrogen could be nitrified even at 7 degrees suggesting BAF can be used for a water reuse method as well as an effective add-on facility in cold regions. However, BAF was not stable with CSO application at increased flow rates suggesting CSO must be equalised prior to application. Disinfection was necessary even during normal weather conditions.  相似文献   
996.
A contact probe test was developed to characterize the surface stickiness of a tomato pulp droplet at various moisture contents and temperatures. To provide tomato pulp samples with different moisture contents, tomato powder produced by a laboratory spray dryer was wetted to seven different moisture levels. The instantaneous tensile force curve was recorded during the probe withdrawal from which the maximum tensile force and other useful information were obtained and cross-examined against images of bonding, debonding, and failure of the material. Generally, at higher moisture contents tomato pulp exhibited cohesive failure followed by semi-adhesive failure, but when moisture content decreased to a certain level, a peak tensile pressure was observed and the failure was adhesive. In addition, higher temperatures shifted the points of adhesive failure toward lower moisture content.  相似文献   
997.
998.
Translated from Khimicheskoe i Neftyanoe Mashinostroenie, No. 5, pp. 6–7, May, 1989.  相似文献   
999.
The theory of deconvolution of infra-red spectra is presented and illustrated using milk protein spectra. The advantage of this method is impressively demonstrated and its relevance for dairy farming shown using a simple example, the cooling of milk.  相似文献   
1000.
Phytic acid-rich particles were isolated from a combined density fraction (CDF) of Great Northern beans. CDF contained more than 80% of the total phytic acid, and 70% of the total crude protein and substantial amounts of certain minerals. CDF had phytic acid in both water soluble and water insoluble forms. An isolate containing phytic acid-rich particles was prepared from CDF using a Tris-base solution. The phytic acid-rich isolate contained 26.6% phytic acid, 34.3% protein, 30.0% total carbohydrates, 0.6% calcium, 2.1% magnesium, and 0.3% potassium. Chemical analysis and fractionation of CDF indicated that the water insoluble form of phytic acid in Great Northern beans was present as a salt of calcium-magnesium-potassium in association with proteins.  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