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排序方式: 共有388条查询结果,搜索用时 15 毫秒
1.
Thiamine Deficiency Complex (TDC) is an ongoing problem impacting salmonine health in various waterbodies, including Lake Ontario. The prevalence of TDC has been variable and explanations for differences are limited. In the current study, thiamine concentrations were measured in eggs, liver tissue, and muscle tissue sampled from brown trout (Salmo trutta), Chinook salmon (Oncorhynchus tshawytscha), coho salmon (O. kisutch), lake trout (Salvelinus namaycush), and steelhead trout (O. mykiss) that were collected from Lake Ontario and its surrounding tributaries. The occurrence of TDC was measured for each species based on TDC-induced offspring mortality rates under laboratory conditions. TDC-induced offspring mortality was observed for all species except brown trout. For affected species, egg free thiamine (Th) was consistently low compared to lake trout collected from Lake Superior that are considered thiamine replete. In addition, species with the lowest percentages of Th in their eggs were the most susceptible to TDC, suggesting that limited thiamine reserves in the form of Th may cause TDC-induced offspring mortality. Lastly, our results show that egg thiamine concentrations have yearly variation and increased for all species throughout the study. Reasons for such variation are undetermined; but, if egg thiamine concentrations continue to increase, the impacts of TDC on these salmonine species may lessen. Future monitoring is needed for determining if thiamine concentrations are increasing and the potential impacts that may have on the entire Lake Ontario fishery. 相似文献
2.
Zhenling Liu 《Energy Sources, Part B: Economics, Planning, and Policy》2018,13(3):169-172
The most important characteristics and limitations of solar energy were reviewed in this study. The analysis of different aspects indicated that the most important global challenges of solar energy development were climatic challenges, technical constraints, and unwillingness to make investments. After describing current conditions and predicting the future of solar energy, this study analyzed the policies formulated by developed countries to develop this from of energy. Accordingly, China has gotten ahead of other countries in this industry due to the technological production of solar panels and governmental supports. Finally, the economic estimation of solar energy was presented by dealing with the economic barriers to this form of energy in developed countries. According to the significant growth in the reduction of solar energy electricity production cost, this source of energy can be used as a major source in the future. It was then recommended to use a hybrid of solar energy with other sources such as wind to reduce the costs. 相似文献
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4.
美国国家公园规划体系评述 总被引:18,自引:3,他引:18
对美国国家公园规划体系进行了调查,介绍了美国国家公园规划发展的三个阶段,物质形态规划(Master Plan)阶段,综合行动计划(Comprehensive Action Plan)阶段和决策体系(Framework of Decision Making)阶段及每个阶段的特点,总结了美国现行国家公园规划决策体系的逻辑关系和构成要素,最后对美国国家公园规划进行了评述。 相似文献
5.
Deborah G. Martin Azadeh Hadizadeh Esfahani Olivia R. Williams Richard Kruger Joseph Pierce James DeFilippis 《Housing Studies》2020,35(3):395-414
AbstractDiscourses regarding homeownership in the United States emphasize housing as an economic investment. This focus fosters a number of problems, including inflated housing values, increased segregation, economic divisions, and the foreclosure crisis. Community land trusts (CLTs) put land in a non-profit trust to keep it affordable long-term. We examine CLTs as affordable housing organizations where individual residents own homes in the trust and lease the land underneath from the CLT. Interviews of CLT homeowners and staff in Minnesota, USA, show that the use value of CLT housing creates opportunities for different life choices. CLT homeowners cite stability and autonomy as the primary benefits of homeownership. They expressed newfound confidence and freedom to pursue personal goals and live less restricted lives after moving into CLT homes, a finding also emphasized by CLT staff. Limited equity housing such as CLTs can both reinforce dominant meanings of homeownership as providing security and autonomy, while also fostering access and affordability for low-income residents. 相似文献
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分析美国的《工程索引》EI和《科学引文索引》SCI的基础上,该文研究了美国的EI对中国建筑学期刊的检索情况,目前只有《华中建筑》和《新建筑》两种期刊入录EI。EI收录《华中建筑》和《新建筑》对我们有十分重要的意义,表明这两种建筑学期刊已经具备了国际性影响。该文提供了在最近年度EI收录《华中建筑》的25篇论文目录。 相似文献
8.
Incidence of adenoviruses in raw and treated water 总被引:6,自引:0,他引:6
Adenoviruses are of major public health importance and are associated with a variety of clinical manifestations, i.e. gastroenteritis, eye infections and respiratory infections. The importance of water in the epidemiology of adenoviruses and the potential health risks constituted by adenoviruses in water sources and supplies are widely recognised. This study was conducted to assess the incidence of human adenoviruses in raw and treated water systems. Various raw and treated water were routinely monitored for the presence of adenoviruses, over a 1-year period (July 2000-June 2001). The supplies were derived from acceptable quality surface water sources using treatment processes, which conform to international standards for the production of safe drinking water. Adenoviruses were detected by firstly amplifying the viruses in cell cultures and then amplifying the extracted nucleic acids of these viruses using molecular techniques (nested PCR). The results indicated human adenoviruses present in 13 (12.75%) of the raw and 9 (4.41%) of the treated water samples tested. The combination of cell culture and nested PCR has proved to be a quick and reliable method for the detection of adenoviruses in water environments. 相似文献
9.
Hwasoo Lee Felipe Caliari Sanjay Sampath 《Journal of the European Ceramic Society》2019,39(13):3749-3755
The thermoelectric properties of calcium cobaltite deposits produced by the plasma spray process are investigated from room-temperature to 873 K. Synthesis of Ca3Co2O6 and Ca2Co2O5 powders were prepared by the solid-state reaction from CaO and CoOx starting powders. During their subsequent plasma spray Ca particles experience preferential evaporation within the plasma, resulting in a complex interplay among process conditions, stoichiometry, and resultant phases. The as-sprayed material predominantly contains amorphous and secondary phases. Upon annealing, the deposits show sensitivity to phase evolution and therefore thermoelectric properties. Through screening studies, optimal annealing conditions were identified which show a p-type Seebeck coefficient value of 180 μV K?1, electrical conductivity of 1.09 × 104 S m?1, thermal conductivity of 1.16 W m-1 K-1 at 873 K. The resultant figure of merit value reached 0.266 for this combination of processing and thermal treatment and is in line with data reported from other techniques for this system. 相似文献
10.
Yohannes Yihdego Bediaku G. Kafui Zarko Veljkovic 《Energy Sources, Part A: Recovery, Utilization, and Environmental Effects》2018,40(17):2079-2096
Oil shale is an organic-rich, fine-grained sedimentary rock, containing kerogen, from which liquid hydrocarbons (called shale oil) can be produced. The oil shale deposits in the Tigray region are found in the northern parts of Ethiopia, Eastern Africa. They are of Upper Paleozoic in age, existing as remnants of the Cretaceous erosion period, underlain by tillites and overlain by sandstones. They were formed during the glacial retreat followed by marine deposition of shales in a basin created by the enormous load of the glaciers. The Ethiopian-Tigray oil shale deposits cover an area extending over approximately 30 km2, with an average mineable bed-thickness of 55 m, showing on the upper part inter-beds and laminations of shaley limestones. The oil shale resources in this region are estimated to be approximately 4 billion tonnes. The exploitation of the Ethiopian-Tigray oil shale deposits is an excellent alternative to fulfill the fuel and other petroleum products’ demand of Ethiopia. This study sheds light on the oil shale resources in the Ethiopian region of Tigray, as they are fairly investigated, regarding their geological characterization, and future strategies for their exploration and exploitation potential. In addition, the oil shale deposits in Jordan are also moderately investigated, as Jordan is considered a promising country for shale oil, taking into account that Jordan has no other hydrocarbon resources (such as crude oil and natural gas), unlike many other countries in the MENA (Middle East and North Africa) region, as MENA sets on “seas” of oil and natural gas. Furthermore, oil shale in the USA is also briefly investigated, as the USA is being the world’s largest country of oil shale resources and reserves. Also, some other issues related to the oil shale industry are investigated, such as economics, extraction technologies of shale oil, and the environmental impacts. 相似文献