全文获取类型
收费全文 | 3092篇 |
免费 | 329篇 |
国内免费 | 138篇 |
专业分类
电工技术 | 365篇 |
技术理论 | 1篇 |
综合类 | 259篇 |
化学工业 | 257篇 |
金属工艺 | 61篇 |
机械仪表 | 120篇 |
建筑科学 | 290篇 |
矿业工程 | 97篇 |
能源动力 | 383篇 |
轻工业 | 176篇 |
水利工程 | 206篇 |
石油天然气 | 84篇 |
武器工业 | 21篇 |
无线电 | 435篇 |
一般工业技术 | 304篇 |
冶金工业 | 91篇 |
原子能技术 | 134篇 |
自动化技术 | 275篇 |
出版年
2024年 | 7篇 |
2023年 | 51篇 |
2022年 | 73篇 |
2021年 | 96篇 |
2020年 | 106篇 |
2019年 | 87篇 |
2018年 | 97篇 |
2017年 | 114篇 |
2016年 | 114篇 |
2015年 | 133篇 |
2014年 | 180篇 |
2013年 | 257篇 |
2012年 | 205篇 |
2011年 | 242篇 |
2010年 | 164篇 |
2009年 | 186篇 |
2008年 | 154篇 |
2007年 | 234篇 |
2006年 | 197篇 |
2005年 | 153篇 |
2004年 | 108篇 |
2003年 | 106篇 |
2002年 | 80篇 |
2001年 | 62篇 |
2000年 | 48篇 |
1999年 | 44篇 |
1998年 | 32篇 |
1997年 | 29篇 |
1996年 | 32篇 |
1995年 | 25篇 |
1994年 | 26篇 |
1993年 | 19篇 |
1992年 | 16篇 |
1991年 | 10篇 |
1990年 | 11篇 |
1989年 | 12篇 |
1988年 | 9篇 |
1987年 | 2篇 |
1986年 | 6篇 |
1985年 | 8篇 |
1984年 | 6篇 |
1983年 | 2篇 |
1980年 | 2篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1965年 | 1篇 |
1964年 | 1篇 |
1961年 | 2篇 |
1956年 | 1篇 |
1954年 | 1篇 |
排序方式: 共有3559条查询结果,搜索用时 15 毫秒
1.
邵啸 《皮革制作与环保科技》2021,(5):146-147
危险废物具有各种危害性,不仅对人体健康有着威胁,对于环境治理来说也有着极大的消极影响。就目前来说,虽然安全填埋技术已经较为成熟,但在实际实施过程中还是容易出现渗漏事故,渗漏液在地下容易穿透防渗层,从而影响地下水,所以这也是我们需要重视的问题之一。 相似文献
2.
Yuan Liu Baodong Chen Wei Li Lulu Zu Wei Tang Zhong Lin Wang 《Advanced functional materials》2021,31(38):2104770
A sustainable power source is a key technical challenge for practical applications of electrically responsive soft robots, especially the required voltage is over several thousand volts. Here, a practicable new technology, triboelectric soft robot (TESR) system with the primary characteristics of power source from mechanical energy, is developed. At its heart is TESR with bioinspired architectures made of soft-deformable body and two triboelectric adhesion feet, which is driven and accurately controlled through triboelectric effect, while reaching maximum crawling speeds of 14.9 mm s−1 on the acrylic surface. The characteristics of the TESR, including displacement and force, are tested and simulated under the power of a rotary freestanding triboelectric nanogenerator (RF-TENG). Crawling of TESR is successfully realized on different materials surfaces and different angle slopes under the driven of RF-TENG. Furthermore, a real-time visual monitoring platform, in which TESR carries a micro camera to transmit images in a long narrow tunnel, is also achieved successfully, indicating that it can be used for fast diagnosis in an area inaccessible to human beings in the future. This study offers a new insight into the sustainable power source technologies suitable for electrically responsive soft robots and contributes to expanding the applicability of TENGs. 相似文献
3.
水利工程的特殊性,决定了其在安全管理构建中更加注重全过程管理机制的构建,以及危险源下的精准安全管控。在传统安全管理模式之下,水利工程安全管理盲点多、效率低,不利于全过程安全管理的高效实施。文章立足水利工程的危险辨识,分析了水利工程危险源全过程安全管理中的问题,并在此基础之上,从强化危险源精准辨识、构建危险源动态管理机制、优化危险源评价工作、加快危险源信息库建设等方面,具体论述了危险源下水利工程全过程安全管理措施。 相似文献
4.
提取鸭骨骼肌肌钙蛋白I(skeletal muscle troponin I,sTnI)用于制备单克隆抗体,并对抗体性能进行 评价。将鸭骨骼肌提取后经十二烷基硫酸钠-聚丙烯酰胺凝胶电泳(sodium dodecyl sulfate polyacrylamide gel electropheresis,SDS-PAGE)测定,取凝胶条带免疫小鼠,融合后经筛选获得分泌抗鸭sTnI的杂交瘤细胞株,用 酶联免疫吸附测定法检测抗体效价、亚型及特异性等特性。结果表明:鸭骨骼肌提取物经SDS-PAGE后出现2 条 颜色较深的条带,取分子质量24 kDa条带用于免疫;筛选后获得2 株单克隆抗体,其中3E7特异性较好,效价在 1∶1.0×105以上,为IgG1亚型,亲和常数(Ka)为5.9×105 L/mol;免疫印迹结果显示,抗体3E7能与鸭骨骼肌提取 物反应,与牛、羊、鸡、鱼骨骼肌提取物无明显反应。 相似文献
5.
Jorge Humberto Luna-Domínguez Héctor Téllez-Jiménez Heriberto Hernández-Cocoletzi Margarita García-Hernández José Aaron Melo-Banda Håkan Nygren 《Ceramics International》2018,44(18):22583-22591
Biomaterials that meet the requirements to stimulate bone tissue formation play a vital role in orthopedics and dentistry. In this work, chitosan and a biphasic, non-cytotoxic material hydroxyapatite/whitlockite were obtained from natural sources, which are available as organic waste. The osteogenic activity was assessed using a rabbit model animal with a chitosan barrier membrane in combination with a bone-filling graft substitute composed of hydroxyapatite/whitlockite. FT-IR results showed the typical absorption bands of the chitosan and hydroxyapatite. Moreover, the X-ray diffraction pattern revealed a typical hexagonal phase of hydroxyapatite and rhombohedral structures related to whitlockite. Masson's trichrome stain showed an early formation of extracellular matrix mineralized, in accord with the surface morphology of a cortical mature bond observed by Scanning Electron Microscopy. The immunocytochemistry results showed a significant increase of positive immunoreactive cells to osteonectin in the treated defects in comparison with the control defects 6 and 8 weeks postoperatively. Overall, the results confirm that the use of this low-cost and versatile biomaterial as a barrier membrane and a bone substitute graft are useful for bone tissue engineering. 相似文献
6.
ABSTRACT The value of social network analysis is critically dependent on the comprehensive and reliable identification of actors and their relationships. We compare regional knowledge networks based on different types of data sources, namely, co-patents, co-publications, and publicly subsidized collaborative R&D projects. Moreover, by combining these three data sources, we construct a multilayer network that provides a comprehensive picture of intraregional interactions. By comparing the networks based on the data sources, we address the problems of coverage and selection bias. We observe that using only one data source leads to a severe underestimation of regional knowledge interactions, especially those of private sector firms and independent researchers. 相似文献
7.
In this paper, the problem of terahertz pulsed imaging and reconstruction is addressed. It is assumed that an incomplete (subsampled) three dimensional THz data set has been acquired and the aim is to recover all missing samples. A sparsity-inducing approach is proposed for this purpose. First, a simple interpolation is applied to incomplete noisy data. Then, we propose a spatio-temporal dictionary learning method to obtain an appropriate sparse representation of data based on a joint sparse recovery algorithm. Then, using the sparse coefficients and the learned dictionary, the 3D data is effectively denoised by minimizing a simple cost function. We consider two types of terahertz data to evaluate the performance of the proposed approach: THz data acquired for a model sample with clear layered structures (e.g., a T-shape plastic sheet buried in a polythene pellet), and pharmaceutical tablet data (with low spatial resolution). The achieved signal-to-noise-ratio for reconstruction of T-shape data, from only 5% observation was 19 dB. Moreover, the accuracies of obtained thickness and depth measurements for pharmaceutical tablet data after reconstruction from 10% observation were 98.8%, and 99.9%, respectively. These results, along with chemical mapping analysis, presented at the end of this paper, confirm the accuracy of the proposed method. 相似文献
8.
为明确洪泽湖(泗洪片区)国考断面水质超标的污染来源,界定各行政区对洪泽湖的影响权重,建立洪泽湖水环境数学模型,模拟不同风向影响下洪泽湖的TN、TP浓度场,分析各主要入湖河流对洪泽湖的影响权重。根据各入湖河流内外源污染物量,利用污染影响权重计算方法,分析不同行政区对洪泽湖(泗洪片区)国考断面污染权重。计算结果表明,龙集镇北断面的污染来源受徐州市影响最大,占50%左右;成河乡断面污染来源受泗洪县、徐州市的影响较大,均占30%左右;对临淮乡断面影响最大的是泗洪县内部的污染,占40%左右。 相似文献
9.
It is necessary to reduce hydrogen consumption to meet increasingly strict environmental and product-quality regulations for refinery plants. In this paper, the concentration potential concepts proposed for design of water-using networks are extended to synthesis of hydrogen networks with multiple contaminants. In the de-sign procedure, the precedence of processes is determined by the values of concentration potential of demands. The usage of complementary source pair(s) to reduce utility consumption is investigated. Three case studies are presented to il ustrate the effectiveness of the method. It is shown that the design procedure has clear engineer-ing meaning. 相似文献
10.
Automatic load shedding is the ultimate countermeasure against imbalance in a power system and can effectively help preventing large blackouts. Taking into account a high penetration of renewable energy sources (RES) in the distribution grid, a clear distinction between load and generation at the PCC becomes increasingly more difficult. For that reason an adaptation of frequency relay parameters and their locations of installation are necessary. In Europe this is rest on a multi-step plan based on values such as the yearly peak load. In this paper a novel probabilistic method for automatic load shedding is presented that uses the average values instead of peak values for load shedding. Its applicability is verified by a dynamic power system model that was developed to compare the classical and novel probabilistic load shedding principle. The method is verified using data from a German TSO. 相似文献