全文获取类型
收费全文 | 3266篇 |
免费 | 194篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 13篇 |
综合类 | 4篇 |
化学工业 | 983篇 |
金属工艺 | 49篇 |
机械仪表 | 49篇 |
建筑科学 | 134篇 |
矿业工程 | 6篇 |
能源动力 | 47篇 |
轻工业 | 519篇 |
水利工程 | 38篇 |
石油天然气 | 7篇 |
无线电 | 123篇 |
一般工业技术 | 486篇 |
冶金工业 | 632篇 |
原子能技术 | 9篇 |
自动化技术 | 362篇 |
出版年
2024年 | 6篇 |
2023年 | 47篇 |
2022年 | 151篇 |
2021年 | 181篇 |
2020年 | 91篇 |
2019年 | 95篇 |
2018年 | 107篇 |
2017年 | 118篇 |
2016年 | 105篇 |
2015年 | 89篇 |
2014年 | 104篇 |
2013年 | 193篇 |
2012年 | 196篇 |
2011年 | 250篇 |
2010年 | 197篇 |
2009年 | 163篇 |
2008年 | 203篇 |
2007年 | 184篇 |
2006年 | 131篇 |
2005年 | 105篇 |
2004年 | 96篇 |
2003年 | 62篇 |
2002年 | 72篇 |
2001年 | 47篇 |
2000年 | 43篇 |
1999年 | 39篇 |
1998年 | 33篇 |
1997年 | 30篇 |
1996年 | 37篇 |
1995年 | 29篇 |
1994年 | 28篇 |
1993年 | 34篇 |
1992年 | 23篇 |
1991年 | 6篇 |
1990年 | 18篇 |
1989年 | 14篇 |
1988年 | 6篇 |
1987年 | 15篇 |
1986年 | 8篇 |
1985年 | 16篇 |
1984年 | 11篇 |
1983年 | 11篇 |
1982年 | 8篇 |
1981年 | 9篇 |
1980年 | 7篇 |
1979年 | 7篇 |
1977年 | 7篇 |
1976年 | 10篇 |
1975年 | 3篇 |
1973年 | 3篇 |
排序方式: 共有3461条查询结果,搜索用时 15 毫秒
1.
Brian Lawn David Marshall Rishi Raj Greg Hirth Trevor Page Julie Yeomans 《Journal of the American Ceramic Society》2021,104(1):23-26
Crystalline quartz has long been identified as among the weakest of abundant crustal minerals. This weakness is particularly evident around the α–β phase inversion at 573°C, in which Si–O bonds undergo a displacive structural transformation from trigonal to hexagonal symmetry. Here we present data using indentation testing methodologies that highlight the precipitous extent of the transformational weakening. Although the indentations are localized over relatively small specimen contact areas, the data quantify the essential deformation and fracture properties of quartz in a predominantly (but not exclusively) compressive stress field, at temperatures and pressures pertinent to conditions in the earth's crust. 相似文献
2.
3.
4.
5.
6.
7.
Sophia X. Sui Lana J. Williams Kara L. Holloway-Kew Natalie K. Hyde Julie A. Pasco 《International journal of molecular sciences》2021,22(1)
Sarcopenia is the loss of skeletal muscle mass and function with advancing age. It involves both complex genetic and modifiable risk factors, such as lack of exercise, malnutrition and reduced neurological drive. Cognitive decline refers to diminished or impaired mental and/or intellectual functioning. Contracting skeletal muscle is a major source of neurotrophic factors, including brain-derived neurotrophic factor, which regulate synapses in the brain. Furthermore, skeletal muscle activity has important immune and redox effects that modify brain function and reduce muscle catabolism. The identification of common risk factors and underlying mechanisms for sarcopenia and cognition may allow the development of targeted interventions that slow or reverse sarcopenia and also certain forms of cognitive decline. However, the links between cognition and skeletal muscle have not been elucidated fully. This review provides a critical appraisal of the literature on the relationship between skeletal muscle health and cognition. The literature suggests that sarcopenia and cognitive decline share pathophysiological pathways. Ageing plays a role in both skeletal muscle deterioration and cognitive decline. Furthermore, lifestyle risk factors, such as physical inactivity, poor diet and smoking, are common to both disorders, so their potential role in the muscle–brain relationship warrants investigation. 相似文献
8.
Ricardo Cambraia Parreira Diana Paola Gmez‐Mendoza Itamar Couto Guedes de Jesus Rafael Pereira Lemos Anderson Kennedy Santos Cristiana Perdigo Rezende Henrique Csar Pereira Figueiredo Mauro Cunha Xavier Pinto Frank Kjeldsen Silvia Guatimosim Rodrigo Ribeiro Resende Thiago Verano‐Braga 《Proteomics. Clinical applications》2020,14(4)
9.
Nicolas Guerda; DeSilva Angela M.; Grey Kathleen S.; Gonzalez-Eastep Diana 《Canadian Metallurgical Quarterly》2006,37(6):702
Currently, ethnic and racial minority individuals represent a large proportion of the U.S. population, and researchers expect that they will represent the majority of the population by 2050. This shift in U.S. demographics calls for a greater awareness and integration of cultural issues into the assessment and treatment of ethnically and linguistically diverse clients. This article examines the unique beliefs and manifestations of illnesses among Haitians in connection with the American Psychological Association's (APA, 2002) Multicultural Guidelines. The authors use a common culture-bound syndrome, Séizisman, to illustrate the cultural beliefs, assessment, and treatment of illnesses among Haitians. In so doing, they demonstrate how to incorporate the APA Multicultural Guidelines into treatment with clients of diverse cultural and racial backgrounds. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
10.
Sheldon H. Jacobson Julie L. Virta Jon M. Bowman John E. Kobza John J. Nestor 《IIE Transactions》2003,35(3):259-269
Aviation security protects vital national interests, as well as passengers and aircraft. Key components of an aviation security system include baggage and passenger screening devices and operations. Determining how and where to assign (deploy) such devices can be quite challenging. Moreover, even after such systems are in place, it can be difficult to measure their effectiveness. This paper describes how discrete optimization models can be used to address these questions, based on three performance measures that quantify the effectiveness of airport baggage screening security device systems. These models are used to solve for optimal airport baggage screening security device deployments considering the number of passengers on a set of flights who have not been cleared using a security risk assessment system in use by the Federal Aviation Administration (i.e., passengers whose baggage is subjected to screening), the number of flights in this set, and the size of the aircraft for such flights. Several examples are provided to illustrate these results, including an example that uses data available from the Official Airline Guide. 相似文献