全文获取类型
收费全文 | 320379篇 |
免费 | 5038篇 |
国内免费 | 725篇 |
专业分类
电工技术 | 6324篇 |
综合类 | 568篇 |
化学工业 | 49514篇 |
金属工艺 | 10496篇 |
机械仪表 | 9127篇 |
建筑科学 | 8363篇 |
矿业工程 | 892篇 |
能源动力 | 8966篇 |
轻工业 | 33482篇 |
水利工程 | 2659篇 |
石油天然气 | 3733篇 |
武器工业 | 10篇 |
无线电 | 40291篇 |
一般工业技术 | 60290篇 |
冶金工业 | 57287篇 |
原子能技术 | 5516篇 |
自动化技术 | 28624篇 |
出版年
2021年 | 2739篇 |
2020年 | 1987篇 |
2019年 | 2508篇 |
2018年 | 4105篇 |
2017年 | 3989篇 |
2016年 | 4072篇 |
2015年 | 2920篇 |
2014年 | 4938篇 |
2013年 | 15278篇 |
2012年 | 8106篇 |
2011年 | 10911篇 |
2010年 | 8492篇 |
2009年 | 9733篇 |
2008年 | 10181篇 |
2007年 | 10089篇 |
2006年 | 8934篇 |
2005年 | 8151篇 |
2004年 | 8006篇 |
2003年 | 7744篇 |
2002年 | 7556篇 |
2001年 | 7704篇 |
2000年 | 7347篇 |
1999年 | 7674篇 |
1998年 | 17898篇 |
1997年 | 13009篇 |
1996年 | 10227篇 |
1995年 | 7973篇 |
1994年 | 7277篇 |
1993年 | 6962篇 |
1992年 | 5319篇 |
1991年 | 5094篇 |
1990年 | 4963篇 |
1989年 | 4807篇 |
1988年 | 4697篇 |
1987年 | 3898篇 |
1986年 | 4027篇 |
1985年 | 4741篇 |
1984年 | 4307篇 |
1983年 | 4052篇 |
1982年 | 3618篇 |
1981年 | 3778篇 |
1980年 | 3476篇 |
1979年 | 3431篇 |
1978年 | 3233篇 |
1977年 | 3826篇 |
1976年 | 4871篇 |
1975年 | 2787篇 |
1974年 | 2665篇 |
1973年 | 2680篇 |
1972年 | 2215篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
Rodríguez-Pérez Ángel Mariano Pérez-Calañas Cinta Pulido-Calvo Inmaculada 《Water Resources Management》2021,35(6):1977-1990
Water Resources Management - This paper aims to evaluate the possibility of using non-utilized hydraulic energy in urban water distribution systems. For this purpose, the viability and possible... 相似文献
72.
73.
Zhang Xi Wang Xianhai Zhao Hongke Ordóñez de Pablos Patricia Sun Yongqiang Xiong Hui 《Scientometrics》2019,119(3):1311-1344
Scientometrics - Altmetrics indices are increasingly applied to measure scholarly influence in recent years because they can reflect the influence of research outputs more timely comparing with... 相似文献
74.
Wireless Personal Communications - Cloud computing is a growing technology where lot of heterogeneous resources are available and large amount of requests are submitted by the customers... 相似文献
75.
76.
Yilin Yang Siddarth K. Achar John R. Kitchin 《American Institute of Chemical Engineers》2022,68(6):e17653
The degree of rate control (DRC) quantitatively identifies the kinetically relevant (sometimes known as rate-limiting) steps of a complex reaction network. This concept relies on derivatives which are commonly implemented numerically, for example, with finite differences (FDs). Numerical derivatives are tedious to implement, and can be problematic, and unstable or unreliable. In this study, we demonstrate the use of automatic differentiation (AD) in the evaluation of the DRC. AD libraries are increasingly available through modern machine learning frameworks. Compared with the FDs, AD provides solutions with higher accuracy with lower computational cost. We demonstrate applications in steady-state and transient kinetics. Furthermore, we illustrate a hybrid local-global sensitivity analysis method, the distributed evaluation of local sensitivity analysis, to assess the importance of kinetic parameters over an uncertain space. This method also benefits from AD to obtain high-quality results efficiently. 相似文献
77.
Maria A. Ospina Monica Pizarro Thierry Tran Julien Ricci John Belalcazar Jorge L. Luna Luis F. Londoño Sandra Salazar Hernan Ceballos Dominique Dufour Luis A. Becerra Lopez-Lavalle 《International Journal of Food Science & Technology》2021,56(3):1343-1353
The objective of this study was to characterise the nutritional potential of leaves and identify a diversity centre with low cyanide and high nutrient content among 178 Latin American cassava genotypes. This field-based collection represents the seven diversity centres, held at The International Center for Tropical Agriculture (CIAT Palmira, Colombia) by the Cassava Program. The cyanide, all-trans-β-carotene and lutein concentrations in cassava leaves ranged from 346 to 7484 ppm dry basis (db), from 174–547 μg g−1 db and 15–181 μg g−1 db, respectively. Cassava leaves also showed significant levels of essential amino acids leucine, lysine, phenylalanine, valine and threonine, and average total protein content of 26.24 g 100 g−1 db. Among seven diversity centres, South American rainforest group showed low cyanide and high carotene content in leaves. In addition, VEN77 and PAN51 genotypes stood out for having low cyanide in leaves and roots and high carotene in leaves. This genetic diversity can be used to select high potential progenitors for breeding purposes. 相似文献
78.
Dr. Alejandra A. Carriles Alberto Mills Dr. María-José Muñoz-Alonso Dr. Dolores Gutiérrez Dr. Juan M. Domínguez Prof. Dr. Juan A. Hermoso Prof. Dr. Federico Gago 《Chembiochem : a European journal of chemical biology》2021,22(2):374-391
Spontaneous mutations in the EEF1A2 gene cause epilepsy and severe neurological disabilities in children. The crystal structure of eEF1A2 protein purified from rabbit skeletal muscle reveals a post-translationally modified dimer that provides information about the sites of interaction with numerous binding partners, including itself, and maps these mutations onto the dimer and tetramer interfaces. The spatial locations of the side chain carboxylates of Glu301 and Glu374, to which phosphatidylethanolamine is uniquely attached via an amide bond, define the anchoring points of eEF1A2 to cellular membranes and interorganellar membrane contact sites. Additional bioinformatic and molecular modeling results provide novel structural insight into the demonstrated binding of eEF1A2 to SH3 domains, the common MAPK docking groove, filamentous actin, and phosphatidylinositol-4 kinase IIIβ. In this new light, the role of eEF1A2 as an ancient, multifaceted, and articulated G protein at the crossroads of autophagy, oncogenesis and viral replication appears very distant from the “canonical” one of delivering aminoacyl-tRNAs to the ribosome that has dominated the scene and much of the thinking for many decades. 相似文献
79.
Geetha R. Madhusudhan V. Padmavathy T. Lallithasree A. 《Wireless Personal Communications》2019,108(3):1957-1976
Wireless Personal Communications - The majority of security systems for wireless sensor networks are based on symmetric encryption. The main open issue for these approaches concerns the... 相似文献
80.
D.R. Santos‐Peñate C.M. Campos‐Rodríguez J.A. Moreno‐Pérez 《International Transactions in Operational Research》2019,26(1):340-363
The ‐centroid problem or leader–follower problem is generalized considering different customer choice rules where a customer may use facilities belonging to different firms, if the difference in travel distance (or time) is small enough. Assuming essential goods, some particular customer choice rules are analyzed. Linear programming formulations for the generalized ‐medianoid and ‐centroid problems are presented and an exact solution approach is applied. Some computational examples are included. 相似文献