全文获取类型
收费全文 | 8489篇 |
免费 | 477篇 |
国内免费 | 336篇 |
专业分类
电工技术 | 518篇 |
综合类 | 1025篇 |
化学工业 | 1181篇 |
金属工艺 | 249篇 |
机械仪表 | 434篇 |
建筑科学 | 882篇 |
矿业工程 | 506篇 |
能源动力 | 197篇 |
轻工业 | 704篇 |
水利工程 | 342篇 |
石油天然气 | 303篇 |
武器工业 | 67篇 |
无线电 | 451篇 |
一般工业技术 | 449篇 |
冶金工业 | 525篇 |
原子能技术 | 87篇 |
自动化技术 | 1382篇 |
出版年
2024年 | 16篇 |
2023年 | 41篇 |
2022年 | 140篇 |
2021年 | 184篇 |
2020年 | 187篇 |
2019年 | 128篇 |
2018年 | 102篇 |
2017年 | 143篇 |
2016年 | 203篇 |
2015年 | 212篇 |
2014年 | 653篇 |
2013年 | 453篇 |
2012年 | 664篇 |
2011年 | 613篇 |
2010年 | 495篇 |
2009年 | 559篇 |
2008年 | 425篇 |
2007年 | 572篇 |
2006年 | 508篇 |
2005年 | 449篇 |
2004年 | 444篇 |
2003年 | 412篇 |
2002年 | 304篇 |
2001年 | 271篇 |
2000年 | 257篇 |
1999年 | 188篇 |
1998年 | 145篇 |
1997年 | 120篇 |
1996年 | 87篇 |
1995年 | 63篇 |
1994年 | 54篇 |
1993年 | 30篇 |
1992年 | 28篇 |
1991年 | 11篇 |
1990年 | 17篇 |
1989年 | 14篇 |
1988年 | 6篇 |
1987年 | 7篇 |
1986年 | 9篇 |
1984年 | 6篇 |
1983年 | 5篇 |
1964年 | 7篇 |
1963年 | 3篇 |
1962年 | 3篇 |
1961年 | 7篇 |
1959年 | 4篇 |
1958年 | 4篇 |
1957年 | 11篇 |
1956年 | 3篇 |
1955年 | 7篇 |
排序方式: 共有9302条查询结果,搜索用时 15 毫秒
1.
一场新型冠状病毒肺炎疫情的爆发给染料行业的发展带来了影响,既有负面消极,也有积极影响。疫情将促进染料行业绿色发展,推动染料行业走向信息化、智能化时代,走向高质量发展,指出只要坚持绿色、创新和智能化,就能战胜疫情,推动中国染料行业稳健发展。 相似文献
2.
铝灰渣是铝熔铸过程中产生的废弃物。本文主要介绍了酒钢东兴铝业嘉峪关分公司铝灰渣的产生量、排放、利用情况、化学成分及表面特征,并简要介绍了铝灰渣、铝灰的循环利用途径。 相似文献
3.
This paper is the second one of the two papers entitled “Weighted Superposition Attraction (WSA) Algorithm”, which is about the performance evaluation of the WSA algorithm in solving the constrained global optimization problems. For this purpose, the well-known mechanical design optimization problems, design of a tension/compression coil spring, design of a pressure vessel, design of a welded beam and design of a speed reducer, are selected as test problems. Since all these problems were formulated as constrained global optimization problems, WSA algorithm requires a constraint handling method for tackling them. For this purpose we have selected 6 formerly developed constraint handling methods for adapting into WSA algorithm and analyze the effect of the used constraint handling method on the performance of the WSA algorithm. In other words, we have the aim of producing concluding remarks over the performance and robustness of the WSA algorithm through a set of computational study in solving the constrained global optimization problems. Computational study indicates the robustness and the effectiveness of the WSA in terms of obtained results, reached level of convergence and the capability of coping with the problems of premature convergence, trapping in a local optima and stagnation. 相似文献
4.
Mizuki Tenjimbayashi Sadaki Samitsu Yuko Watanabe Yasuyuki Nakamura Masanobu Naito 《Advanced functional materials》2021,31(21):2010957
Liquid marble (LM) is a droplet that is wrapped by hydrophobic solid particles, which behave as a non-wetting soft solid. Based on these properties, LM can be applied in fluidics and soft device applications. A wide variety of functional particles have been synthesized to form functional LMs. However, the formation of multifunctional LMs by integrating several types of functional particles is challenging. Here, a general strategy for the flexible patterning of functional particles on droplet surfaces in a patchwork-like design is reported. It is shown that LMs can switch their macroscopic behavior between a stable and active state on super-repellent surfaces in situ by jamming/unjamming the surface particles. Active LMs hydrostatically coalesce to form a self-sorted particle pattern on the droplet surface. With the support of LM handling robotics, on-demand cyclic activation–manipulation–coalescence–stabilization protocols by LMs with different sizes and particle types result in the reliable design of multi-faced LMs. Based on this concept, a single bi-functional LM is designed from two mono-functional LMs as an advanced droplet carrier. 相似文献
5.
进入新发展阶段,中国水资源安全保障需要以“节水优先、空间均衡、系统治理、两手发力”治水思路为指导,厘清问题、研判趋势、优化对策,支撑新阶段水利高质量发展。本文在全面分析我国水资源安全保障存在的突出问题与面临形势基础上,阐述了新发展阶段中国水资源安全保障的基本思路与战略路径,从保证资源安全、构建国家水网、强化供水保障、建设美丽河湖、改善水环境质量等方面提出了战略对策和需要进一步回答的重大问题,以期为完善新发展阶段中国水资源安全保障战略,全面提高国家水资源安全保障能力提供有力支撑。 相似文献
6.
《Food Control》2015
A telephone survey was carried out on 13,486 randomly selected households located in the Abruzzo region (central Italy). Three questionnaires were specifically designed in relation to three different groups of foods (Meat and meat products, Fishery products, Fruit and vegetables). Questions were mainly focused on the amount and number of purchases, type of retailer, and home food handling practices with respect to the week prior to the interview. Data were classified according to a multilingual thesaurus system (LanguaL). Results allowed to estimate domestic purchases (in kg) per capita for different food categories. The category “Red meat/Cattle” accounted for a large part of purchases in the “meat and meat products” group (10.9 kg per capita/year; 32.2% of purchases in the group) while the category “Fish or related organism/Fish” was the most purchased in the “fishery products” group (6.9 kg per capita/year; 63.3%). The aggregation of more detailed characteristics enabled the identification of popular categories of foods, such as “Red meat/Cattle/Divided into pieces” (25% of the “meat and meat products” group). Significant differences (p < 0.05) were found between the four different provinces (L'Aquila, Chieti, Pescara and Teramo) with respect to “Poultry/Chicken” and “Red meat/Cattle” categories. Householders were also asked about post-purchase food handling practices that might be hazardous to food safety. More than 20% of those surveyed stated that they thawed frozen meat at room temperature. The degree of doneness after cooking of different food categories was generally high: over 90% of products purchased in the majority of meat and fish categories were properly cooked. However a noticeable proportion of householders (about 15%) reported medium or rare cooking of “Red meat/Cattle” and “Red meat/Swine”. Differences (p < 0.05) were also found between consumers of different ages, with people over 65 years old being more prone to freeze meat and cook it thoroughly.The survey was carried out in a specific geographic area and on a statistically significant sample of households, thus allowing a collection of data on domestic habits relating to food purchases and home food handling practices. This information should be included in the framework of quantitative microbial risk assessment (QMRA) models as a measure of the actual exposure of consumers to pathogenic microorganism. The LanguaL system also proved to be a practical language-independent method useful not only to identify and describe food items but also to classify them according to specific food safety characteristics. 相似文献
7.
针对水利工程开发方案优选具有多目标、多层次等特点,建立灰局势决策模型并应用变异系数法确定评价指标权重。利用该模型对灌区改建扩建规划方案进行优选,结果表明这是一种有效的方法。 相似文献
8.
大同市节水型社会建设的探讨 总被引:1,自引:0,他引:1
大同市是全国108个比较严重缺水城市之一,人均水资源量不足全国的1/10(全国人均水资源量2231m^3),稍超过全省的1/2(全省人均水资源量388m^3),市中心城区工农业及城市生活用水近20年来靠超采地下水来支撑。文中就大同市水资源供需不平衡的现状,提出大同市节水型社会建设的必要性,及今后水资源开源和节流的措施。 相似文献
9.
10.