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   385篇
  免费   49篇
  国内免费   19篇
电工技术   20篇
综合类   18篇
化学工业   53篇
金属工艺   15篇
机械仪表   19篇
建筑科学   39篇
矿业工程   11篇
能源动力   22篇
轻工业   93篇
水利工程   27篇
石油天然气   4篇
武器工业   1篇
无线电   23篇
一般工业技术   29篇
冶金工业   5篇
原子能技术   1篇
自动化技术   73篇
  2024年   1篇
  2023年   17篇
  2022年   37篇
  2021年   47篇
  2020年   32篇
  2019年   24篇
  2018年   11篇
  2017年   11篇
  2016年   12篇
  2015年   14篇
  2014年   29篇
  2013年   26篇
  2012年   52篇
  2011年   32篇
  2010年   18篇
  2009年   26篇
  2008年   6篇
  2007年   17篇
  2006年   13篇
  2005年   6篇
  2004年   2篇
  2003年   2篇
  2002年   5篇
  2000年   1篇
  1999年   4篇
  1997年   1篇
  1996年   1篇
  1994年   1篇
  1993年   1篇
  1991年   1篇
  1987年   3篇
排序方式: 共有453条查询结果,搜索用时 15 毫秒
101.
人类社会的发展使得水资源与水环境问题日益突出,传统水资源单一数量承载力已不能满足水资源规划与管理的需求。本文从水质水量耦合角度构建了量质平衡方程和针对水功能区划水质目标的地表水资源可利用量计算方法,在此基础上提出了以人口数量与GDP规模为表征指标的水资源承载力计算模型。该模型利用人口空间展布的方法将社会经济指标拆分到水资源分区,用承载水平下的生活用水量与Ⅰ—Ⅲ类水资源可利用量平衡关系对结果进行试算检验,考虑了水质水量对水资源承载力的双重约束,也反映了地表水资源可利用量的动态变化特性。模型在沂河流域进行了应用,选用CODcr为污染物控制指标,分析计算了沂河流域不同水平年的水资源承载力,验证了模型计算结果的合理性与科学性。计算结果可以评估和预测流域未来时期的水资源承载程度,为流域/区域经济社会的可持续发展提供依据。  相似文献   
102.
With the growing demand for interior design solutions that are friendly to the green environment, there is a growing awareness of interior designers around the world to the sustainability strategy. Most of the traditional interior design and construction process consumes many natural resources in the manufacturing and installation process. This will harm the environment. Interior designers adopted a sustainable design technology, the opportunity to improve the healthy indoor air quality. To achieve sustainable solutions, materials, construction methods, furniture by selecting the lighting design options. Despite much sustainable design research, discussion of the interior design of sustainability criteria there little. Essential for sustainable standard interior design solutions to support the responsible interior designer. Therefore, this study aims to propose a set of criteria for selecting based on sustainable indoor network processors and embedded system design solutions to ensure a sustainable and consistent product mix of 3DWeb representation of interior design solutions thing. Finally, to enhance its functionality, come to an end because of the importance of effective standards.  相似文献   
103.
Molecular dynamics (MD) simulation is a crucial tool for understanding principles behind important biochemical processes such as protein folding and molecular interaction. With the rapidly increasing power of modern computers, large-scale MD simulation experiments can be performed regularly, generating huge amounts of MD data. An important question is how to analyze and interpret such massive and complex data.One of the (many) challenges involved in analyzing MD simulation data computationally is the high-dimensionality of such data. Given a massive collection of molecular conformations, researchers typically need to rely on their expertise and prior domain knowledge in order to retrieve certain conformations of interest. It is not easy to make and test hypotheses as the data set as a whole is somewhat “invisible” due to its high dimensionality. In other words, it is hard to directly access and examine individual conformations from a sea of molecular structures, and to further explore the entire data set. There is also no easy and convenient way to obtain a global view of the data or its various modalities of biochemical information.To this end, we present an interactive, collaborative visual analytics tool for exploring massive, high-dimensional molecular dynamics simulation data sets. The most important utility of our tool is to provide a platform where researchers can easily and effectively navigate through the otherwise “invisible” simulation data sets, exploring and examining molecular conformations both as a whole and at individual levels. The visualization is based on the concept of a topological landscape, which is a 2D terrain metaphor preserving certain topological and geometric properties of the high dimensional protein energy landscape. In addition to facilitating easy exploration of conformations, this 2D terrain metaphor also provides a platform where researchers can visualize and analyze various properties (such as contact density) overlayed on the top of the 2D terrain. Finally, the software provides a collaborative environment where multiple researchers can assemble observations and biochemical events into storyboards and share them in real time over the Internet via a client-server architecture.The software is written in Scala and runs on the cross-platform Java Virtual Machine. Binaries and source code are available at http://www.aylasoftware.org and have been released under the GNU General Public License.  相似文献   
104.
Green technology for the preparation of epoxidized soybean oil ( ESBO ) is of significance.The epoxidation of soybean oil with peroxyacetic acid generated in situ from hydrogen peroxide and glacial ace...  相似文献   
105.
利用生石灰和工业废料磷石膏组成复合材料化剂,对不同初始含水率的疏浚淤泥进行材料化处理,使其成为工程填土材料,研究磷石膏作为材料化剂辅助添加剂的效果及磷石膏部分替代生石灰的可行性.试验结果表明:磷石膏的加入,短期内相当于增加干料,可以提高材料化土的早期强度;随着龄期的增加,添加磷石膏的材料化土无侧限抗压强度增加率较单掺生石灰的材料化土有大幅提高;短期之内,生石灰-磷石膏材料化土的渗透性与单掺生石灰的淤泥材料化土的渗透性相比变化不大,随着龄期增大,生石灰-磷石膏复合材料化土的渗透性较单掺生石灰材料化土有所下降.  相似文献   
106.
为确保智能变电站继电保护装置二次回路稳定性与可靠性,本文设计了基于多参信息量的继电保护二次回路故障在线监控与诊断系统。基于网络报文记录分析装置的功能特性,配置其与继电保护设备间链路关联性,获得二次回路核心报文数据信息,传输于调度端以综合分析,以获取SV、GOOSE网络链路实时状态与回路故障在线诊断方法策略。  相似文献   
107.
In present study, effect of interfacial heat transfer with ambient gas on the onset of oscillatory convection in a liquid bridge of large Prandtl number on the ground is systematically investigated by the method of linear stability analyses. With both the constant and linear ambient air temperature distributions, the numerical results show that the interfacial heat transfer modifies the free-surface temperature distribution directly and then induces a steeper temperature gradient on the middle part of the free surface, which may destabilize the convection. On the other hand, the interfacial heat transfer restrains the temperature disturbances on the free surface, which may stabilize the convection. The two coupling effects result in a complex dependence of the stability property on the Biot number. Effects of melt free-surface deformation on the critical conditions of the oscillatory convection were also investigated. Moreover, to better understand the mechanism of the instabilities, rates of kinetic energy change and “thermal” energy change of the critical disturbances were investigated  相似文献   
108.
The directional solidification in the undercooled pure melt influenced by a transverse far field flow was studied by using the multiple scale method. The result shows that in the boundary layer near the liquid-solid interface, when affected by a transverse far field flow, the temperature distribution in the direction of crystal growth presents an oscillatory and decay front in the side of liq- uid phase. The crucial distinguishing feature of a temperature pattern due to the transverse convection is the additional periodic modulation of the pattern in the growth direction. The wave number and eigenvalue that satisfy the Mullins-Sekerka dispersion rela- tion are suppressed by the transverse far field flow.  相似文献   
109.
110.
目的:探讨山楂原花青素(hawthorn proanthocyanidin,HPC)和VC联合通过Wnt/β-catenin通路减轻胰岛素抵抗大鼠氧化应激的机制。方法:80 只雄性Wistar大鼠通过高脂膳食法建立胰岛素抵抗模型,10 只饲喂普通饲料作为对照组,检测大鼠造模前后体质量变化和造模后空腹血糖、血清胰岛素浓度,比色法检测血清丙氨酸氨基转移酶(alanine aminotransferase,ALT)、天冬氨酸氨基转移酶(aspartate aminotransferase,AST)和碱性磷酸酶(alkaline phosphatase,ALP)活力;随机选取50 只造模成功的胰岛素抵抗大鼠分为模型组、HPC组(56 μg/mL)、VC组(180 μg/mL)、HPC(56 μg/mL)+VC(180 μg/mL)组和二甲双胍(2 μg/mL)组,每组各10 只。连续给药12 周,测定各组大鼠血液中葡萄糖、胰岛素浓度以及肝匀浆中超氧化物歧化酶(superoxide dismutase,SOD)、过氧化氢酶(catalase,CAT)、谷胱甘肽过氧化物酶(glutathione peroxidase,GPx)、还原型谷胱甘肽(glutathione,GSH)、丙二醛(malondialdehyde,MDA)的水平;实时定量聚合酶链式反应检测Wnt1、轴蛋白(Axin)、糖原合酶激酶-3β(glycogen synthasc kinase-3β,GSK-3β)、腺瘤样息肉病蛋白(adenomatous polyposis coli protein,APC)、β-catenin、过氧化物酶体增殖物激活受体γ(peroxisome proliferators-activated receptors γ,PPARγ)的mRNA表达水平;蛋白质印迹法检测肝组织Wnt1、β-catenin和PPARγ的蛋白表达水平;荧光共振能量转移分析法检测Wnt1和Dsh蛋白结合的情况。结果:80 只大鼠给予高脂膳食喂养,有54 只造模成功,成功率67.5%。造模后,模型组大鼠的体质量以及空腹血糖、血清胰岛素、ALT、AST和ALP水平均极显著高于对照组大鼠(P<0.01)。与模型组相比,HPC组、HPC+VC组和二甲双胍组大鼠肝匀浆中各指标水平均有极显著差异(P<0.01),HPC+VC组对肝匀浆中各指标干预效果显著优于HPC组(P<0.05);HPC+VC组Wnt1和β-catenin的mRNA相对表达水平极显著降低(P<0.01),Axin、GSK-3β、APC和PPARγ的mRNA相对表达水平极显著升高(P<0.01);HPC+VC组Wnt1和β-catenin的蛋白相对表达水平极显著降低(P<0.01),PPARγ的蛋白表达水平极显著升高(P<0.01);HPC+VC组的荧光共振能量转移信号明显减弱,说明随着时间的延长,Wnt1与Dsh之间的结合力明显减弱,形成的异源二聚体数量明显减少。结论:HPC和VC联合可通过Wnt/β-catenin通路改善胰岛素抵抗大鼠肝脏氧化应激状况。  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