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   210篇
  免费   10篇
  国内免费   4篇
电工技术   1篇
综合类   2篇
化学工业   8篇
机械仪表   1篇
建筑科学   66篇
矿业工程   4篇
能源动力   31篇
轻工业   17篇
水利工程   21篇
石油天然气   11篇
无线电   4篇
一般工业技术   15篇
冶金工业   25篇
原子能技术   2篇
自动化技术   16篇
  2022年   3篇
  2021年   10篇
  2020年   4篇
  2019年   5篇
  2018年   3篇
  2017年   8篇
  2016年   8篇
  2015年   5篇
  2014年   9篇
  2013年   24篇
  2012年   5篇
  2011年   20篇
  2010年   17篇
  2009年   22篇
  2008年   7篇
  2007年   13篇
  2006年   11篇
  2005年   8篇
  2004年   11篇
  2003年   4篇
  2002年   2篇
  2001年   4篇
  2000年   4篇
  1999年   7篇
  1998年   2篇
  1997年   1篇
  1996年   2篇
  1994年   1篇
  1985年   2篇
  1983年   1篇
  1981年   1篇
排序方式: 共有224条查询结果,搜索用时 218 毫秒
1.
This paper presents the development of a bottom-up stock model to perform a holistic energy study of the Mexican non-domestic sector. The current energy and exergy flows are shown based on a categorisation by climatic regions with the aim of understanding the impact of local characteristics on regional efficiencies. Due to the limited data currently available, the study is supported by the development of a detailed archetype-based stock model using EnergyPlus as a first law analysis tool combined with an existing exergy analysis method. Twenty-one reference models were created to estimate the electric and gas use in the sector. The results indicate that sectoral energy and exergy annual input are 95.37 PJ and 94.28 PJ, respectively. Regional exergy efficiencies were found to be 17.8%, 16.6% and 23.2% for the hot-dry, hot-humid and temperate climates, respectively. The study concludes that significant potential for improvements still exists, especially in the cases of space conditioning, lighting, refrigeration, and cooking where most exergy destructions occur. Additionally, this work highlights that the method described may be further used to study the impact of large-scale refurbishments and promote national regulations and standards for sustainable buildings that takes into consideration energy and exergy indicators.  相似文献   
2.
Development of Mexican hydrocarbon reservoirs by foreign operators has become possible under Mexico's new Hydrocarbon Law, effective as per January 2015. Our study compares the economic returns of shallow water fields in the Gulf of Mexico applying the royalty and taxes due under the fiscal regimes of the U.S. and Mexico. The net present value (NPV) of the base case scenario is US$1.4 billion, assuming standard development and production cost (opex, capex), 10% discount rate accounting for the cost of capital and revenues computed using a reference oil price of $75/bbl. The impact on NPV of oil price volatility is accounted for in a sensitivity analysis. The split of the NPV of shallow water hydrocarbon assets between the two contractual parties, contractor and government, in Mexico and the U.S. is hugely different. Our base case shows that for similar field assets, Mexico's production sharing agreement allocates about $1,150 million to the government and $191 million to the contractor, while under U.S. license conditions the government take is about $700 million and contractor take is $553 million. The current production sharing agreement leaves some marginal shallow water fields in Mexico undeveloped for reasons detailed and quantified in our study.  相似文献   
3.
ABSTRACT

In recent years, there has been much debate concerning the relative pros and cons of purchasing medications from foreign markets such as Mexico and Canada. The following study compares the content uniformity and weight variation for three medicinal products, acquired from pharmacies in both Mexico and the United States: amoxicillin capsules (500 mg), amoxicillin/clavulanic acid suspension (400 mg and 57 mg/5 mL, respectively), and furosemide tablets (40 mg). Twenty capsules/tablets were individually weighed and a designated aliquot was taken. Following dissolution in an appropriate solvent and sonication, a sample was taken and analyzed via high performance liquid chromatography (HPLC). The suspensions were prepared according to directions on the label. Five samples of the suspensions were then taken and analyzed via an appropriate HPLC method. The content uniformity for the amoxicillin capsules was found to be 15.4 ± 2.4% and 99.4 ± 9.3%, for Mexican and U.S. capsules, respectively. The percent relative standard deviation (% RSD) for weight variation was found to be 8.7% and 1.5% for capsules obtained from Mexico and the United States, respectively. Content uniformity analysis for the Mexican suspension product resulted in an average of 85.5 ± 1.2% for amoxicillin and 98.6 ± 1.9% for the clavulanic acid content, while the results for the U.S. suspension product were 104.4 ± 3.1% and 117.8 ± 3.6% for amoxicillin and clavulanic acid, respectively. Content uniformity for the furosemide tablets was found to be 90.3 ± 4.8% and 95.6 ± 2.1% for Mexican and U.S. tablets, respectively. The % RSD of weight variation for the Mexican tablets was 2.1%, while the % RSD for the U.S. tablets was found to be 1.0%. From the three products tested, content analysis revealed that the amount of active ingredients for two of the products acquired in Mexico were appreciably less than the concentrations for their U.S. counterparts.  相似文献   
4.
An awakening interest in public space in Brazilian cities is emphasising the value of existing civic areas. Guilherme Wisnik , a critic, curator and professor at the Faculty of Architecture and Urbanism of the University of São Paulo, looks at the history and potential future of Brazil's urban spaces. He highlights how despite the introduction of innovative Modernist design in the mid-20th century, which forged ‘a new relationship between architecture, urbanism and landscape design’, more recently the country's cities have been subject to the vicissitudes of market and political forces.  相似文献   
5.
新闻(英文)     
正China,Mexico Sign MOU of Standardization CooperationUnder the witness of Chinese President Xi Jinping and Mexican President Enrique Pe?a Nieto,AQSIQ Minister Zhi Shuping and Mexican Secretary of Economy Ildefonso Guajardo Villarreal signed the memorandum of understanding on standardization technical cooperation on November 13.  相似文献   
6.
《Urban Water Journal》2013,10(4):245-262
Centralized waterborne sanitation faces serious social, economic and environmental sustainability challenges. Dry sanitation (DS) may ease some of those, but it is not known whether DS can be a viable solution at large scales and in urban settings. We assessed DS viability in a broad range of large scale and urban contexts in Mexico. Here, we synthesize the operational and structural barriers encountered across a diversity of sites, provide an understanding of how and why those barriers arose and propose a set of strategies through which those barriers can be addressed. We include reference to other large-scale and urban experiences outside Mexico.  相似文献   
7.
The Process Analysis tools of the Community Multiscale Air Quality (CMAQ) modeling system together with back-trajectory analysis were used to assess potential contributors to ozone episodes that occurred during June 1-4, 2006, in three populated U.S.-Mexico border twin cities: San Diego/Tijuana, Imperial/Mexicali and El Paso/Ciudad Juárez. Validation of CMAQ output against surface ozone measurements indicates that the predictions are acceptable with regard to commonly recommended statistical standards and comparable to other reported studies. The mean normalized bias test (MNBT) and mean normalized gross error (MNGE) for hourly ozone fall well within the US EPA suggested range of ± 15% and 35%, respectively, except MNBT for El Paso. The MNBTs for maximum 8-h average ozone are larger than those for hourly ozone, but all the simulated maximum 8-h average ozone are within a factor of 2 of those measured in all three regions. The process and back-trajectory analyses indicate that the main sources of daytime ground-level ozone are the local photochemical production and regional transport. By integrating the effects of each process over the depth of the daytime planetary boundary layer (PBL), it is found that in the San Diego area (SD), chemistry and vertical advection contributed about 36%/48% and 64%/52% for June 2 and 3, respectively. This confirms the previous finding that high-altitude regional transport followed by fumigation contributes significantly to ozone in SD. The back-trajectory analysis shows that this ozone was mostly transported from the coastal area of southern California. For the episodes in Imperial Valley and El Paso, respectively, ozone was transported from the coastal areas of southern California and Mexico and from northern Texas and Oklahoma.  相似文献   
8.
Abstract

Present and future improvements in efficiency of the water sector in Mexico depend on the development of a cadre of well-trained professional managers in the public and private sectors, as well as on the strengthening of the private and public sector institutions. Considerable investments are needed, but the efforts will pay back in terms of more rational policy-making and management practices. This paper analyzes several important exercises on capacity building in Mexico, which took place between 1990 and 2000. Present efforts on capacity building, achievements, and concerns are also considered in terms of the training and education needed to build a new generation of water professionals who can meet the current challenges and the needs of the coming decades. The needs of the water sector in terms of capacity building have been assessed in Mexico several times in the past. The conclusions and the results have always been the same: there is an urgent need to develop better educated managers and water professionals, both in terms of numbers and skills. Even though the needs have been identified repeatedly for over a decade, and despite continuous official rhetorics on the importance and urgency of capacity building, no long-term country-specific program on capacity building has yet been developed, let alone implemented.  相似文献   
9.
The state of Michoacán, one of the states with the lowest economic development in Mexico, has been historically recognized because of its potential for tourism activities. The revenues coming from this economic sector, as well as the number of tourists who visit this state have significantly increased during the last few years. A survey was conducted on tourists who visited Michoacán, in order to determine the visitors' profile and their satisfaction levels during their visit. A cluster analysis was then used to categorize the lifestyle of these tourists into five different segments, to be able to develop the best tourism products, marketing strategies and aid the decision-making process of government and private organizations related to this sector. A regression analysis was also performed to identify the variables that determine the satisfaction of these tourists. The results are satisfactory in the sense that the actions taken, which were based on this research and led by the Ministry of Tourism of Michoacán and the Ministry of Tourism of Mexico, have attracted more national and international groups, and have also increased the revenues, profits and new investments reported by private organizations related to this economic sector.  相似文献   
10.
墨西哥成矿分带及与侵入岩相关矿床分布规律   总被引:1,自引:0,他引:1  
王磊  柳玉龙  李丰收  陈伟 《矿产勘查》2014,5(4):663-671
墨西哥地质格局由古老的基底残片与古洋壳不断增生拼合而成,共划分为斑岩型、角砾岩型,脉状、浸染状Cu-Mo-Au成矿带;岩浆热液型浸染状、脉状及网脉状Cu-Au-Ag成矿带;喷流型、接触交代型脉状及层状Pb-Zn-Cu-Ag成矿带;块状硫化物型Cu-Pb-Zn-Au-Ag成矿带;碱性金属和贵金属成矿带;IOCG铁矿床成矿带6个成矿带。并根据侵入岩侵位特征及相关矿床分布,确定中生代晚期及新生代岩浆岩矿床主要分布在墨西哥中西部西马德雷—南马德雷岛弧带上,矿床类型以斑岩型、夕卡岩型、浅成低温热液型、块状硫化物型、热液交代型、喷流沉积型、铁氧化物铜金型(IOCG)为主。文章介绍了墨西哥的地质概况、成矿分带、与侵入岩相关的矿床分布规律及特征。  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