全文获取类型
收费全文 | 13705篇 |
免费 | 601篇 |
国内免费 | 153篇 |
专业分类
电工技术 | 430篇 |
综合类 | 384篇 |
化学工业 | 2424篇 |
金属工艺 | 470篇 |
机械仪表 | 476篇 |
建筑科学 | 779篇 |
矿业工程 | 170篇 |
能源动力 | 394篇 |
轻工业 | 1032篇 |
水利工程 | 173篇 |
石油天然气 | 298篇 |
武器工业 | 34篇 |
无线电 | 1754篇 |
一般工业技术 | 2046篇 |
冶金工业 | 1904篇 |
原子能技术 | 91篇 |
自动化技术 | 1600篇 |
出版年
2025年 | 18篇 |
2024年 | 221篇 |
2023年 | 188篇 |
2022年 | 301篇 |
2021年 | 440篇 |
2020年 | 327篇 |
2019年 | 313篇 |
2018年 | 347篇 |
2017年 | 352篇 |
2016年 | 377篇 |
2015年 | 369篇 |
2014年 | 509篇 |
2013年 | 762篇 |
2012年 | 684篇 |
2011年 | 945篇 |
2010年 | 793篇 |
2009年 | 733篇 |
2008年 | 837篇 |
2007年 | 698篇 |
2006年 | 674篇 |
2005年 | 510篇 |
2004年 | 433篇 |
2003年 | 427篇 |
2002年 | 391篇 |
2001年 | 308篇 |
2000年 | 284篇 |
1999年 | 290篇 |
1998年 | 328篇 |
1997年 | 277篇 |
1996年 | 254篇 |
1995年 | 200篇 |
1994年 | 161篇 |
1993年 | 126篇 |
1992年 | 85篇 |
1991年 | 60篇 |
1990年 | 61篇 |
1989年 | 61篇 |
1988年 | 45篇 |
1987年 | 42篇 |
1986年 | 36篇 |
1985年 | 29篇 |
1984年 | 18篇 |
1983年 | 18篇 |
1982年 | 9篇 |
1981年 | 15篇 |
1980年 | 18篇 |
1979年 | 15篇 |
1978年 | 9篇 |
1976年 | 14篇 |
1975年 | 14篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
Hong Kong is known as a migrant city because its population was sourced from mainland China, and because there has always been outflows of people to overseas countries, especially from the mid-1980s to mid-1990s. Emigration to mainland China has become a significant recent trend. This article discusses this phenomenon in the theoretical contexts of migration and trans-border residential development. It contends that the trend will intensify more quickly than other cross-border movements because the two systems are separated by a political border within one country, and because there are common cultural ties and rapid economic integration. 相似文献
12.
An approach to aid decision making for urban water management is presented that is based on the concept of trade-off sacrifice level in pairwise comparisons between criteria, modelled using fuzzy logic. This approach is illustrated by a case study - selection of alternative water supplies for a Sydney household. Four key decision making criteria covering health, economic, environment and technical aspects are selected: annual probability of infection, life cycle energy use, life cycle cost and reliability. The decision making problem is to select between cases with different volume and application of recycled greywater and rainwater in light of the four criteria. Decision maker's preference is expressed by five levels of trade-off sacrifice between pairs of criteria. The decision makers can assign their preferences for sacrifice level by linguistic assessment and the output trade-off weight (TOW). Measures of decision makers' perceived trade-off level are modelled by a rule-based fuzzy logic control system. The final analysis shows the performance for each sacrifice class for each case, to aid overall decision making with stakeholders. 相似文献
13.
This review paper summarizes current research efforts toward a comprehensive view of wet material dewatering, considering the binding energy as the strength to hold water, and rupture energy given to remove moisture from materials. 相似文献
14.
In shape memory materials,that have been trained to have a two way shape memory effect(TWSM),themartensitic variants are classified into two groups,i.e.,preferentially oriented variants and self-accommodatingvariants.Applied stress may promote or constrain the transition of preferentially oriented variants and so changetransformation temperatures but has no essential effect on self-accommodating variants.According to the pointof view mentioned above,some experimental phenomena during thermocycling of a TWSM device may be ex-plained,such as the absence of synchronization between the plot of resistance change.temperature and the plotof memory strain vs.temperature. 相似文献
15.
1概述洪口水电站位于福建省宁德市洪口乡大道头村,距宁德市城区63 km,是霍童溪干流梯级开发的第六级电站,是1座以发电为主的中型水库工程,调节库容2.404亿m3。电站装机为混流式机 相似文献
16.
随着现今社会互联网、个人终端技术的飞越发展,电子商务越来越多的出现在人们的生活与工作中,这种全新的商务模式具有便捷、高效率、低成本的特点.同时,这种全新的商务模式对管理水平、信息传递技术都提出了更高的要求,其中安全的重要性尤为突出. 相似文献
17.
本文从管理要求与技术要求两个方面指出了实验室管理体系运行中常见的问题,并结合实际情况提出了相应措施,最后对加强实验室管理体系运行有效性提出了几点建议。 相似文献
18.
The commercial finite element package ABAQUS has been used to analyse the crack bridging process by Ti-15 at%V -phase particles dispersed in -TiAl matrix in the presence of particle–matrix decohesion. Both the particle–matrix decohesion potential and the -phase materials constitutive relations are found to have a major effect on the ductility, fracture toughness and failure mode of the – two-phase material. The interface potential is found to primarily affect the distribution of the normal interface strength ahead of the advancing interfacial crack and the mode (gradual versus sudden) of decohesion. The -phase materials constitutive relations are found to influence the location of nucleation of the interfacial cracks and, in turn, the mode of decohesion. A metastable -phase that can plastically deform at low stress levels by undergoing a stress-assisted martensitic transformation, but experience a high rate of strain hardening is found to give rise to the largest levels of ductility and fracture toughness is the – two-phase material. © 1998 Kluwer Academic Publishers 相似文献
19.
20.
Proteomics has long been thought to hold the promise of producing results of clinical utility which will influence patient treatment and outcomes. A recent Wellcome Trust/EBI meeting and retreat--“Perspectives in Clinical Proteomics”--brought together experts from a broad range of stakeholder groups with an interest in ensuring proteomics achieves this aim. This viewpoint presents views derived from these forums, proposing a pathway for the development of next-generation proteomic analyses in the clinical setting from selection of candidates through to their validation and ultimate demonstration of utility through health technology assessments. Although not meant to be all encompassing, important elements for proteomics researchers to consider are presented. 相似文献