全文获取类型
收费全文 | 6005篇 |
免费 | 352篇 |
国内免费 | 279篇 |
专业分类
电工技术 | 358篇 |
综合类 | 1011篇 |
化学工业 | 178篇 |
金属工艺 | 48篇 |
机械仪表 | 282篇 |
建筑科学 | 978篇 |
矿业工程 | 149篇 |
能源动力 | 179篇 |
轻工业 | 166篇 |
水利工程 | 103篇 |
石油天然气 | 125篇 |
武器工业 | 12篇 |
无线电 | 619篇 |
一般工业技术 | 409篇 |
冶金工业 | 428篇 |
原子能技术 | 65篇 |
自动化技术 | 1526篇 |
出版年
2024年 | 43篇 |
2023年 | 49篇 |
2022年 | 78篇 |
2021年 | 148篇 |
2020年 | 157篇 |
2019年 | 99篇 |
2018年 | 95篇 |
2017年 | 118篇 |
2016年 | 155篇 |
2015年 | 176篇 |
2014年 | 400篇 |
2013年 | 448篇 |
2012年 | 423篇 |
2011年 | 453篇 |
2010年 | 358篇 |
2009年 | 417篇 |
2008年 | 381篇 |
2007年 | 409篇 |
2006年 | 350篇 |
2005年 | 317篇 |
2004年 | 322篇 |
2003年 | 292篇 |
2002年 | 241篇 |
2001年 | 193篇 |
2000年 | 98篇 |
1999年 | 95篇 |
1998年 | 48篇 |
1997年 | 47篇 |
1996年 | 40篇 |
1995年 | 37篇 |
1994年 | 19篇 |
1993年 | 17篇 |
1992年 | 13篇 |
1991年 | 6篇 |
1990年 | 5篇 |
1989年 | 9篇 |
1988年 | 5篇 |
1987年 | 5篇 |
1984年 | 6篇 |
1983年 | 5篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1971年 | 3篇 |
1968年 | 4篇 |
1965年 | 5篇 |
1963年 | 4篇 |
1961年 | 5篇 |
1959年 | 3篇 |
1954年 | 3篇 |
排序方式: 共有6636条查询结果,搜索用时 15 毫秒
11.
2006沈阳世界园艺博览会国内展园特色分析 总被引:2,自引:0,他引:2
通过简要分析2006沈阳世界园艺博览会国内展园具有主题突出,特色分明;创意新颖,手法多样;景观有序,布局合理;造园要素,运用得体;环境小品,丰富庭院;造园新材,得到检验等特点,提出沈阳世界园艺博览会在继承传统造园手法的同时,有创新之处. 相似文献
12.
本文着重阐述洪江古商城的窨子屋建筑的融合性特征:在功能上宜商宜居;在建筑外形上呈现出徽派建筑风格,但其内部结构则实现了本土化改造;在装饰风格上具有多元化特征。从而反映出在资本主义萌芽的影响下,过渡性建筑在湘西地区的具体表现。 相似文献
13.
14.
15.
Jeremy Leggett 《Renewable & Sustainable Energy Reviews》1998,2(4):345
Why should renewables advocates care about the arcane business of multilateral climate negotiations? The answer is simple. Because these long-running and oft bogged-down talks have as their ultimate objective a goal with seismic implications for energy markets: substantial reductions in greenhouse gas emissions. Coming anywhere close to that goal would entail the creation of multi-hundred billion dollar markets in renewables in the years ahead. And in Kyoto last December, governments took a meaningful first step in that direction.This paper is a brief summary, and analysis of that first step. It concludes with some observations about immediate implications for the renewables industries. 相似文献
16.
C.A. González-Rugerio R. Fuhrmeister D. Sudhoff J. Pilarczyk A. Górak 《Chemical Engineering Research and Design》2014
The design of catalytic distillation (CD) columns is a challenging task because of the superposition of chemical reaction and distillation in one apparatus. In this work, a method to design a cost-optimal CD column for chemical systems with large number of components and chemical reactions is presented. The method is based on the following steps: (1) estimation of the number of theoretical stages and catalyst volume by the decomposition of the CD column into a sequence of chemical reactors and non-reactive distillation columns, (2) estimation of the column diameter and operating conditions using an equilibrium stage model, and (3) design of the column applying an optimisation algorithm and using a rigorous non-equilibrium stage model to represent the CD process. The method is applied to determine the optimal column configuration and operating conditions for the synthesis of tert-amyl ethyl ether from ethanol and isoamylenes. Eight components and four chemical reactions were selected to represent the chemical system in the simulations. 相似文献
17.
Robert J. Martin 《International journal of molecular sciences》2014,15(10):18742-18746
Unsustainable harvesting of natural fish stocks is driving an ever growing marine aquaculture industry. Part of the aquaculture support industry is net suppliers who provide producers with nets used in confining fish while they are grown to market size. Biofouling must be addressed in marine environments to ensure maximum product growth by maintaining water flow and waste removal through the nets. Biofouling is managed with copper and organic biocide based net coatings. The aquaculture industry provides a case study for business issues related to entry of improved fouling management technology into the marketplace. Several major hurdles hinder entry of improved novel technologies into the market. The first hurdle is due to the structure of business relationships. Net suppliers can actually cut their business profits dramatically by introducing improved technologies. A second major hurdle is financial costs of registration and demonstration of efficacy and quality product with a new technology. Costs of registration are prohibitive if only the net coatings market is involved. Demonstration of quality product requires collaboration and a team approach between formulators, net suppliers and farmers. An alternative solution is a vertically integrated business model in which the support business and product production business are part of the same company. 相似文献
18.
19.
Box–Jenkins (1970) models are often used to capture the autoregressive moving average of past observations of tourist arrivals from Japan to Taiwan and New Zealand. However, other explanatory variables, such as real income in the origin country, have also affected the demand for international travel. The purpose of this paper is to use the ARMAX model to investigate the dynamic relationship between tourism demand and real income of Japan, and to compare the findings with the single-equation model. Unit root tests and diagnostics are performed before estimating the income elasticity of travel demand by Japan for New Zealand and Taiwan based on seasonally unadjusted quarterly data for 1980(1) to 2004(2). The empirical results of the ARMAX model support the economic theory that the demand for international travel is positively related to income of the origin country. 相似文献
20.
本文在简要回顾国际放射防护委员会(ICRP)历史的基础上,首先指出在伴随着核辐射和核能的应用不断发展的同时,由ICRP基本建议书推荐的辐射防护体系也在实际应用中不断完善和改进。接着简要介绍了目前倍受关心的两个实际问题及其有关初步建议。文中再次强调了ICRP的几个重要基本观点,以及与此相悖的“打擦边球”和“零危险”两种偏面看法。最后指出,我们应该在借鉴国际经验的同时,认真总结自己的经验,为全世界共同的辐射防护事业作出我们应有的贡献。 相似文献