全文获取类型
收费全文 | 23607篇 |
免费 | 2365篇 |
国内免费 | 1647篇 |
专业分类
电工技术 | 459篇 |
技术理论 | 3篇 |
综合类 | 2083篇 |
化学工业 | 5861篇 |
金属工艺 | 2092篇 |
机械仪表 | 605篇 |
建筑科学 | 3667篇 |
矿业工程 | 617篇 |
能源动力 | 413篇 |
轻工业 | 1105篇 |
水利工程 | 323篇 |
石油天然气 | 623篇 |
武器工业 | 149篇 |
无线电 | 664篇 |
一般工业技术 | 3217篇 |
冶金工业 | 3125篇 |
原子能技术 | 232篇 |
自动化技术 | 2381篇 |
出版年
2024年 | 109篇 |
2023年 | 439篇 |
2022年 | 771篇 |
2021年 | 946篇 |
2020年 | 951篇 |
2019年 | 878篇 |
2018年 | 830篇 |
2017年 | 963篇 |
2016年 | 951篇 |
2015年 | 951篇 |
2014年 | 1263篇 |
2013年 | 1406篇 |
2012年 | 1445篇 |
2011年 | 1734篇 |
2010年 | 1342篇 |
2009年 | 1371篇 |
2008年 | 1283篇 |
2007年 | 1408篇 |
2006年 | 1286篇 |
2005年 | 1169篇 |
2004年 | 985篇 |
2003年 | 891篇 |
2002年 | 744篇 |
2001年 | 574篇 |
2000年 | 390篇 |
1999年 | 361篇 |
1998年 | 281篇 |
1997年 | 238篇 |
1996年 | 181篇 |
1995年 | 143篇 |
1994年 | 144篇 |
1993年 | 108篇 |
1992年 | 88篇 |
1991年 | 66篇 |
1990年 | 80篇 |
1989年 | 52篇 |
1988年 | 36篇 |
1987年 | 33篇 |
1986年 | 38篇 |
1984年 | 35篇 |
1980年 | 30篇 |
1979年 | 28篇 |
1966年 | 28篇 |
1965年 | 31篇 |
1964年 | 49篇 |
1963年 | 39篇 |
1960年 | 26篇 |
1959年 | 29篇 |
1958年 | 30篇 |
1955年 | 46篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
51.
Six misconceptions about evolutionary approaches to human behavior are exposed. Evidence is adduced to support the assertions that evolutionary approaches do not (a) adopt a reductionistic "gene-centered" level of analysis, (b) assume that natural selection is the only process that creates and designs ontogenetic processes and phenotypic outcomes, (c) assume that genes are the only agents responsible for the transgenerational inheritance of phenotypic traits and characteristics, (d) assume that genes are self-contained and impervious to extragenetic influences, (e) posit a strong form of genetic determinism, or (f) pay lip service to the role of the environment. Building straw men and knocking them down is an inherently destructive enterprise; integrating different approaches is a more constructive way of contributing to the growth of knowledge. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
52.
在世界经济竞争日趋激烈和科技发展突飞猛进的今天,技术创新中介组织将拥有巨大的发展空间。必须针对我国技术创新中介组织的发展现状,规范政府和中介组织的行为。 相似文献
53.
On the basis of the idea that situational norms are mentally represented as associations between environments and normative behavior, it was proposed that an environment can automatically direct normative behavior. More specifically, when situational norms are well-established (e.g., when entering the library, one should be silent), an environment is capable of automatically activating mental representations of normative behavior and the behavior itself. In these experiments, participants were exposed to pictures of environments, and effects on accessibility of representations of normative behavior and on actual behavior were assessed. Results indicated that representations of behavior and actual behavior itself are activated automatically when (a) goals to visit the environment are active and (b) strong associations between environment and normative behavior are established. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
54.
55.
预期回报对决策具有决定性的影响。基于行为经济模型,认为创业决策依赖于预期回报和欲望水平之间的相互作用,并通过计量分析验证了预期回报对创业决策的影响。 相似文献
56.
佟艳 《辽阳石油化工高等专科学校学报》2002,18(1):72-74
在论述邪教基本内涵的基础上,着重从五个方面分别阐述了当代中国邪教的基本特征及其防范的主要措施. 相似文献
57.
This study examines the impact of positive mood on the effective usage of a Decision Support System (DSS). Using current cognitive theories, a theoretical argument about DSS usage is developed. This argument is then investigated via a lab experiment. The results of the lab experiment show that decision makers in positive mood used a greater number of informational cues provided by the DSS and made more accurate judgments. 相似文献
58.
Al-4%Cu过饱和合金在强磁场中时效行为 总被引:1,自引:0,他引:1
采用差示扫描量热仪分析并结合显微硬度测试、电子探针分析、透射电镜观察研究了10-T稳恒强磁场对Al-4%Cu(质量分数)合金130℃时效过程中各沉淀相析出行为的影响。结果表明:在低温时效初期强磁场的引入加速了铜的扩散,降低了G.P.(Ⅰ)区的溶解激活能,促进其溶解,各沉淀相的析出与溶解温度均向低温处移动,时效进程加快;另外,强磁场时效后沉淀相尺寸减小;施加强磁场试样的硬度明显高于未施加磁场试样的,时效硬化效果加强。 相似文献
59.
S. A. Mousavi Dehghani 《Petroleum Science and Technology》2007,25(11):1435-1446
Natural depletion of petroleum reservoirs as well as gas injection for enhance oil recovery, are unavoidable processes in the oil industry. Foremost, prediction of the problems due to these two processes is very necessary and important. So many field and experimental experiences have shown that heavy organic depositions, especially asphaltene deposition, are principal results during these processes. Results of laboratory simulation of asphaltene deposition during the natural depletion of petroleum reservoirs and also during gas injection and enhanced oil recovery (EOR) processes are reported here. This is achieved through the design of a new experimental setup for the investigation of pressure and composition effects on asphaltene deposition in petroleum fluids at high pressure and high temperature conditions. In this work, asphaltene deposition during decreasing pressure, from pressures greater than reservoir pressure to pressures below the bubble point pressure (natural depletion) and also asphaltene deposition during natural gas injection in reservoir conditions, are studied for three samples—one recombined sample and two bottomhole samples. All of the obtained results from this work conform to theoretical and other experimental works. 相似文献
60.
本文研究了TiO2掺入对CaO稳定ZrO2(简称CaSZ-NiCr)金属陶瓷烧结特性的影响,测定了CaSZ-NiCr-TiO2金属陶瓷烧结样品的密度和显微硬度,结果表明,TiO2的掺入能提高CaSZ-NICr金属陶瓷的烧结密度和显微硬度,对CaSZ-NiCr金属陶瓷有助烧结作用.金相观察表明,TiO3的掺入改变了NiCr相在金属陶瓷中的形貌,说明了NiCr与CaSZ的浸润性有一定的改善.XRD和EPMA分析结果显示,TiO2偏聚在NiCr金属相中,不影响CaSZ的稳定性. 相似文献