全文获取类型
收费全文 | 14065篇 |
免费 | 979篇 |
国内免费 | 500篇 |
专业分类
电工技术 | 1809篇 |
综合类 | 1321篇 |
化学工业 | 2226篇 |
金属工艺 | 421篇 |
机械仪表 | 697篇 |
建筑科学 | 976篇 |
矿业工程 | 363篇 |
能源动力 | 1188篇 |
轻工业 | 626篇 |
水利工程 | 608篇 |
石油天然气 | 2709篇 |
武器工业 | 58篇 |
无线电 | 343篇 |
一般工业技术 | 794篇 |
冶金工业 | 357篇 |
原子能技术 | 37篇 |
自动化技术 | 1011篇 |
出版年
2024年 | 60篇 |
2023年 | 207篇 |
2022年 | 341篇 |
2021年 | 406篇 |
2020年 | 470篇 |
2019年 | 415篇 |
2018年 | 358篇 |
2017年 | 458篇 |
2016年 | 457篇 |
2015年 | 483篇 |
2014年 | 794篇 |
2013年 | 835篇 |
2012年 | 779篇 |
2011年 | 973篇 |
2010年 | 709篇 |
2009年 | 721篇 |
2008年 | 570篇 |
2007年 | 781篇 |
2006年 | 697篇 |
2005年 | 633篇 |
2004年 | 504篇 |
2003年 | 547篇 |
2002年 | 420篇 |
2001年 | 449篇 |
2000年 | 489篇 |
1999年 | 422篇 |
1998年 | 311篇 |
1997年 | 286篇 |
1996年 | 249篇 |
1995年 | 202篇 |
1994年 | 134篇 |
1993年 | 94篇 |
1992年 | 83篇 |
1991年 | 50篇 |
1990年 | 14篇 |
1989年 | 20篇 |
1988年 | 13篇 |
1987年 | 14篇 |
1986年 | 13篇 |
1985年 | 22篇 |
1984年 | 17篇 |
1983年 | 22篇 |
1982年 | 8篇 |
1981年 | 4篇 |
1980年 | 6篇 |
1977年 | 1篇 |
1972年 | 1篇 |
1966年 | 1篇 |
1962年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
42.
高效防气防砂一体化管柱的研制与应用 总被引:2,自引:1,他引:1
为解决文南油田高气液比井出砂易造成卡泵的问题,研制了高效防气防砂一体化管柱。该管柱主要由闭式气锚、重力式防气装置和激光割缝筛管3部分组成。闭式气锚的分离作用消除了气体对抽油泵的影响,提高了泵效;重力防气装置利用液气分离原理和高烟囱原理进行液气分离,液流回流时间可达10min,排气最高压差可达0.2MPa;经激光割缝筛管过滤后的液体含砂粒外径小于0.05mm。该管柱在文南油田现场应用16井次,累计增液6000t,增油2717t,平均单井泵效提高7%。 相似文献
43.
44.
目前大型原油储罐逐步应用自动机械清洗系统进行清罐作业,而对于容量小、沉积物较少的油罐国内仍采用人工清洗方式进行。分析了油罐人工清洗作业过程时容易引发火灾的原因,并提出相应的预防火灾措施。 相似文献
45.
Carolyn McGregor Bruce Kneale Mark Tracy 《Journal of Network and Computer Applications》2007,30(4):1309-1323
Premature and ill term babies born in regional Australia must be moved to another hospital with Neonatal Intensive Care Unit (NICU) facilities. Transferred pre-term and critically ill term babies have higher mortality rates and much higher rates of long term disability than similar babies born in hospitals with NICU facilities. This paper details the Bush Babies Broadband project that aims to significantly improve the quality of treatment for babies born in rural, remote as well as urban areas by providing the first on-demand virtual NICU architecture in Australia. Real-time data collected from medical monitors and ventilators attached to the baby, audiovisual streams and static physiological data such as X-ray images are transmitted to the consulting Neonatologist to gain a better picture of the patient's condition than is currently available. The key contribution of this significant research is the infrastructure providing a mechanism for Neonatologists to receive information directly from a regional hospital, thereby preventing, in some cases, the immediate need to move the baby. A key benefit of this framework is that it is available to link regional hospitals with the supporting NICU Neonatologist ‘on demand’ eliminating the need to establish permanent point to point connections. This paper further describes the application of that architecture to a specific pilot connecting the Bathurst regional hospital with Neonatologists within the NICU at Nepean Hospital, Penrith Australia. 相似文献
46.
This paper attempts to shed light on the determinants of energy demand in Turkey. Energy demand model is first proposed using the ant colony optimization (ACO) approach. It is multi-agent systems in which the behavior of each ant is inspired by the foraging behavior of real ants to solve optimization problem. ACO energy demand estimation (ACOEDE) model is developed using population, gross domestic product (GDP), import and export. All equations proposed here are linear and quadratic. Quadratic_ACOEDE provided better-fit solution due to fluctuations of the economic indicators. The ACOEDE model plans the energy demand of Turkey until 2025 according to three scenarios. The relative estimation errors of the ACOEDE model are the lowest when they are compared with the Ministry of Energy and Natural Resources (MENR) projection. 相似文献
47.
48.
Since demand for power exhibits great variability the amount of firm energy to be purchased to meet real time demand based on forecasts is usually different from the realized demand for that period. The role of generation reserves is to meet the real time fluctuations of power demand. The predictable part of the demand is met through purchases of firm energy. In this paper a model is presented to determine optimal quantities of firm energy and generation reserves to meet random demands. The model is then parameterized introducing a set of factors to perform a sensitivity study. A full factorial experiment is designed to study the impact of five factors on the response variable (i.e., proportion of generation reserves on the total purchased quantity). An example consisting of 640 simulations corresponding to 25 treatment combinations evaluated over 20 randomly generated mean demands is used to identify significant factors on the response variable. Results from the experiment suggest that generation reserve requirements should be adjusted considering changes in significant factors and in the mean demand over the dispatch interval. 相似文献
49.
一种广义水驱特征曲线的建立 总被引:2,自引:0,他引:2
广义水驱特征曲线能描述综合含水储量采出程度呈多种不同的凸、S、凹曲线类型。根据油水两相渗流原理,从归一化的油水相对渗透率出发,建立起累积产油、累积产水与综合含水率的积分相关关系,进而建立了累积产油、累积产水与归一化的油水相对渗透率的关系。通过构建积分函数,利用公式形式类比,建立了更一般形式的广义水驱特征曲线。理论分析和实例计算表明,所建立的广义水驱特征曲线与实际数据线性相关性更强,结果更可靠。 相似文献
50.
Argyris G. Kagiannas Thanassis Didis Dimitris Th. Askounis John Psarras 《国际能源研究杂志》2003,27(2):173-186
The needs that an energy supply system must meet are constantly changing, due to technological, social and political reasons. Effective energy planning is a dynamic process that is repeated periodically and adjusts to changing conditions. Energy decision makers and planners are no longer able to rely on inductive decision making since they have to investigate the effect of various decision parameters and possible future changes. To help in this process, models have been developed where estimates of future load growth, candidate power plants, fuels and other key factors can be introduced, from which the planners can evaluate decision parameters and the available alternatives. The paper presents the different methodologies and practices that are used by 11 energy models for energy demand forecasting, supply side management and generation expansion planning, demand side management and integrated resource planning. The paper concludes to the presentation of a strategic appraisal of the examined energy models appropriate for energy planning in Mozambique. Three models are proposed for conducting demand forecasting, generation expansion planning and demand side management. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献