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   850篇
  免费   43篇
电工技术   14篇
化学工业   260篇
金属工艺   24篇
机械仪表   17篇
建筑科学   38篇
能源动力   29篇
轻工业   87篇
水利工程   12篇
石油天然气   1篇
无线电   51篇
一般工业技术   200篇
冶金工业   33篇
原子能技术   4篇
自动化技术   123篇
  2024年   4篇
  2023年   7篇
  2022年   28篇
  2021年   32篇
  2020年   23篇
  2019年   22篇
  2018年   29篇
  2017年   24篇
  2016年   26篇
  2015年   23篇
  2014年   40篇
  2013年   65篇
  2012年   52篇
  2011年   56篇
  2010年   41篇
  2009年   41篇
  2008年   48篇
  2007年   40篇
  2006年   30篇
  2005年   32篇
  2004年   37篇
  2003年   19篇
  2002年   20篇
  2001年   8篇
  2000年   16篇
  1999年   8篇
  1998年   12篇
  1997年   12篇
  1996年   11篇
  1995年   10篇
  1994年   5篇
  1993年   12篇
  1992年   5篇
  1991年   5篇
  1990年   3篇
  1989年   3篇
  1987年   3篇
  1985年   3篇
  1984年   3篇
  1983年   4篇
  1982年   2篇
  1981年   2篇
  1980年   3篇
  1979年   2篇
  1978年   2篇
  1976年   3篇
  1975年   3篇
  1974年   3篇
  1971年   4篇
  1968年   1篇
排序方式: 共有893条查询结果,搜索用时 15 毫秒
61.
Doxorubicin is a commonly used antineoplastic agent in the treatment of many types of cancer. Little is known about the interactions of doxorubicin with cardiac biomolecules. Serious cardiotoxicity including dilated cardiomyopathy often resulting in a fatal congestive heart failure may occur as a consequence of chemotherapy with doxorubicin. The purpose of this study was to determine the effect of exposure to doxorubicin on the changes in major amino acids in tissue of cardiac muscle (proline, taurine, glutamic acid, arginine, aspartic acid, leucine, glycine, valine, alanine, isoleucine, threonine, lysine and serine). An in vitro interaction study was performed as a comparison of amino acid profiles in heart tissue before and after application of doxorubicin. We found that doxorubicin directly influences myocardial amino acid representation even at low concentrations. In addition, we performed an interaction study that resulted in the determination of breaking points for each of analyzed amino acids. Lysine, arginine, β-alanine, valine and serine were determined as the most sensitive amino acids. Additionally we compared amino acid profiles of myocardium before and after exposure to doxorubicin. The amount of amino acids after interaction with doxorubicin was significantly reduced (p = 0.05). This fact points at an ability of doxorubicin to induce changes in quantitative composition of amino acids in myocardium. Moreover, this confirms that the interactions between doxorubicin and amino acids may act as another factor most likely responsible for adverse effects of doxorubicin on myocardium.  相似文献   
62.
Magnetic particle mediated transport in combination with nanomaterial based drug carrier has a great potential for targeted cancer therapy. In this study, doxorubicin encapsulation into the apoferritin and its conjugation with magnetic particles was investigated by capillary electrophoresis with laser-induced fluorescence detection (CE-LIF). The quantification of encapsulated doxorubicin was performed by fluorescence spectroscopy and compared to CE-LIF. Moreover, the significant enhancement of the doxorubicin signal was observed by addition of methanol into the sample solution.  相似文献   
63.
The compression, deformation and material behavior of moist spherical elastic‐plastic zeolite 4A granules under multiple stressing conditions at unique and random contacts were experimentally studied with the help of uniaxial diametrical compression tests. The force‐displacement curves were approximated and the coefficient of restitution was determined using appropriate mechanical models from literature. The phenomenon of cyclic hardening was studied and the critical number of cycles required to reach fracture was determined. Furthermore, the influence of particle size and moisture content on the material behavior at cyclic loading, the coefficient of restitution, and the critical number of cycles required to reach fracture were investigated.  相似文献   
64.
Compression tests of deformation and fracture behavior of wheat grains were carried out at different loading rates that varied from 0.02 to 0.11 mm s–1. The contact model originally developed for the spherical particles was adapted to describe the deformation and fracture behavior of elliptical wheat grains. The distributions of basic fracture parameters of wheat grains such as fracture force, fracture strength, fracture energy, and fracture displacement were fitted with normal distribution function.  相似文献   
65.
The effect of supersaturation, reaction temperature, and mixing intensity on particle size was investigated. Sterical stabilization of barium sulfate suspensions was applied to prevent formation of agglomerates. This allowed a reactant ratio of 1:1, thus maximizing product yield. The local supersaturation is strongly affected by the mixing intensity that can be characterized by Reynolds numbers. The significant decrease in particle size was observed by increasing the Reynolds number from 600 to 8000. A higher reactant concentration leads to a higher degree of supersaturation, and finer particles are precipitated. The particle size can be reduced with increasing reactant concentration. The degree of supersaturation increases with temperature reduction, i.e., the particle size will be reduced at low temperature. In addition, nucleation and growth kinetics are changed in a way that reduces the particle size. The optimized lab‐scale process is capable of producing over 1 kg h–1 of nanoscaled BaSO4 with a median diameter of 75 nm.  相似文献   
66.
A techno‐economic analysis for four different types of biogas plant realizations was performed, including one biogas biorefinery concept. For each concept detail, a process flow diagram was created. Mass and energy balances were estimated. The net present value and payback were calculated for each concept for a better feasibility understanding. The results showed that with the used expensive substrate, namely, wheat straw, the obtained paybacks appeared to be more than 100 years. Sensitivity analysis was done for the price range of a substrate. Critical factors were defined to improve feasibility.  相似文献   
67.
68.
Aroma components of ine resulting from fermentation of grape must from the Verdejo cultivar ere isolated by continuous liquid-liquid extraction and further fractionation on a silica gel column. One hundred and thirty-to substances, including alcohols, esters, carbonyl compounds, terpenes, acids and sulphur compounds, ere identified by using GC-MS; some had not been previously detected in ines. Data are given hich could lead to the characterisation of the Verdejo cultivar and the effect of the elaboration of young ines. The sensory contribution of some volatile compounds to the flavour of Verdejo ine is also studied.  相似文献   
69.
This study was aimed to investigate the influence of solvent (water and ethanol in concentration: 50%, 70% and 96%) and extraction temperature (25–80) °C on polyphenols extraction of grape seed (Vitis vinifera L. cv. “Frankovka”) cultivated in Eastern Croatia. The best results were reached using 50% ethanol at 80 °C. The most abundant individual polyphenolic compound was catechin which makes the average of 45.11% of the total phenolic content followed by epicatechin (34.45%), procyanidin B2 (12.90%), gallic acid (5.34%), gallocatechin (1.58%), epicatechin gallate (1.01%). The antioxidant activity of extracts was determined by DPPH‐method and it was highly dependent on extraction solvent and temperature. The total extractable proanthocyanidins content of extract had the highest positive correlation (r = 0.994) with antioxidant activity, which indicated that these compounds might be the most important antioxidant in examined grape seed extracts. Relationship between phenolic content and colour of extracts was observed.  相似文献   
70.
An implementation of a radix-2 division unit is presented that uses prediction of the quotient digit. This prediction allows the concurrent computation of the quotient digit and the partial remainder. To achieve a simple quotient-digit selection, resulting in a step time roughly half of that of SRT division (without prediction), a simple estimate of the partial remainder is used, which requires that the divisor be scaled close to unity. This prescaling is simple to implement and increases the execution time by two cycles. We estimate a speed-up of 1.5 with respect to SRT division with redundant remainders.  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