全文获取类型
收费全文 | 5496篇 |
免费 | 144篇 |
国内免费 | 88篇 |
专业分类
电工技术 | 63篇 |
综合类 | 123篇 |
化学工业 | 358篇 |
金属工艺 | 152篇 |
机械仪表 | 98篇 |
建筑科学 | 290篇 |
矿业工程 | 36篇 |
能源动力 | 79篇 |
轻工业 | 250篇 |
水利工程 | 48篇 |
石油天然气 | 51篇 |
武器工业 | 24篇 |
无线电 | 319篇 |
一般工业技术 | 497篇 |
冶金工业 | 2989篇 |
原子能技术 | 61篇 |
自动化技术 | 290篇 |
出版年
2023年 | 21篇 |
2022年 | 53篇 |
2021年 | 52篇 |
2020年 | 50篇 |
2019年 | 51篇 |
2018年 | 60篇 |
2017年 | 49篇 |
2016年 | 34篇 |
2015年 | 63篇 |
2014年 | 75篇 |
2013年 | 140篇 |
2012年 | 124篇 |
2011年 | 148篇 |
2010年 | 125篇 |
2009年 | 137篇 |
2008年 | 131篇 |
2007年 | 144篇 |
2006年 | 155篇 |
2005年 | 123篇 |
2004年 | 79篇 |
2003年 | 92篇 |
2002年 | 85篇 |
2001年 | 72篇 |
2000年 | 70篇 |
1999年 | 128篇 |
1998年 | 858篇 |
1997年 | 568篇 |
1996年 | 361篇 |
1995年 | 217篇 |
1994年 | 197篇 |
1993年 | 220篇 |
1992年 | 58篇 |
1991年 | 50篇 |
1990年 | 59篇 |
1989年 | 68篇 |
1988年 | 46篇 |
1987年 | 48篇 |
1986年 | 37篇 |
1985年 | 39篇 |
1984年 | 18篇 |
1983年 | 31篇 |
1982年 | 27篇 |
1981年 | 40篇 |
1980年 | 33篇 |
1979年 | 29篇 |
1978年 | 29篇 |
1977年 | 92篇 |
1976年 | 194篇 |
1975年 | 32篇 |
1973年 | 17篇 |
排序方式: 共有5728条查询结果,搜索用时 750 毫秒
41.
Thomas J. R. Hughes Arif Masud Isaac Harari 《International journal for numerical methods in engineering》1995,38(19):3193-3210
Finite element methods for dynamic analysis employing elements with drilling degrees of freedom are presented. The formulation is based on a variational principle in which displacements and rotations are interpolated independently. The issue of zero masses corresponding to rotational degrees of freedom is addressed and techniques for defining consistent and lumped rotational mass matrices are presented. 相似文献
42.
43.
BA Rybicki MJ Maliarik M Major J Popovich MC Iannuzzi 《Canadian Metallurgical Quarterly》1997,18(4):707-717
Hereditary susceptibility to sarcoidosis is suggested by ethnic preponderance, familial clustering, and multigenerational involvement. The genetics of sarcoidosis cannot be adequately addressed in small samples of patients; a large-scale study with stratification for patient phenotypic differences is necessary. A study that uses both genetic marker and environmental data would be able to control for and examine different causative mechanisms. Until such a well-designed, comprehensive study is carried out, we are left with interesting patterns of disease in families and uncertain allelic associations. 相似文献
44.
EM de Jong BA Seegers MK Gulinck JB Boezeman PC van de Kerkhof 《Canadian Metallurgical Quarterly》1996,193(4):300-303
We present the first case of esophagogastric devascularization and esophagogastric transection using a stapler through laparoscopic surgery. The procedure was performed in a 71-year-old diabetic woman with alcoholic liver cirrhosis (Child-Pugh B class), portal hypertension, bleeding grade III esophageal varices, and a previous bleeding episode. The surgical technique was carried out without problems, and the patient had an excellent postoperative condition. Esophagogastric devascularization with esophageal transection using a stapler through laparoscopic surgery is a feasible technique that accomplishes the same and all objectives of the open procedure. Operative time in both methods is the same, whereas surgical trauma, inmunologic depletion, amount of transfused blood, pain, use of analgesics, and hospital stay are reduced in the laparoscopic technique. 相似文献
45.
46.
复合微粒高性能混凝土的二级界面显微结构及耐久性研究 总被引:8,自引:0,他引:8
将天然纳米纤维材料及活性球形掺合料复合应用于高性能混凝土中,用以改善高性能混凝土的二级界面,探讨胶凝材料的颗粒紧密堆积及显微结构。对混凝土力学性能的研究表明:改善混凝土的二级界面,可以大幅度提高其抗弯强度和弹性模量;对耐久性的研究表明,由于加入了纳米纤维材料,改善了体系颗粒级配及二级界面显微结构,增加了体系密实度,是提高混凝土抗冻性、抗渗性的有效途径。因而,研究高性能混凝土的二级界面显微结构,对于提高高性能混凝土的宏观物理力学性能及耐久性存在巨大潜能。 相似文献
47.
Blascovich Jim; Brennan Kelly; Tomaka Joe; Kelsey Robert M.; Hughes Pamela; Coad Mary Lou; Adlin Richard 《Canadian Metallurgical Quarterly》1992,63(1):164
Investigated in 3 experiments the relationships between affect intensity and basal, evoked, and perceived cardiac arousal. Affect intensity was assessed using R. J. Larsen and E. Diener's (1987) Affect Intensity Measure (AIM). Cardiac arousal was evoked with exercise in the 1st study and with mental arithmetic in the 2nd and 3rd. Perceived cardiac arousal was measured under optimal conditions using a standard heartbeat discrimination procedure. Women as a group scored higher on the AIM. Affect intensity was unrelated to basal or evoked cardiac arousal and was negatively related to perceived cardiac arousal in all 3 studies. Data suggest that affect intensity, although unrelated to actual physiological arousal, is negatively related to the accuracy with which individuals perceive their own arousal. Results are discussed within the context of an expanded arousal-regulation model (J. Blascovich, 1990). (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
48.
A Hughes 《BT Technology Journal》2003,21(4):175-185
Over the last decade, the area of programmable networking seems to have matured significantly; it now attracts interest from
both academic and industrial institutions. Many projects have either focused on or made use of work done in this area; however,
until now, programmable networks have not been used to improve the process of engineering router software. This project does
just this. Previous publications have outlined a software system that makes the experimental analysis of routers — and hence
router software — more accessible to network researchers. The software system provides a configuration system designed to
manage a test-bed consisting of multiple programmable routers. It allows administrators to quickly and easily configure the
test-bed using a high-level policy language. This paper discusses this language and presents rationale for design choices.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
49.
Hughes Rosemary B.; Nosek Margaret A.; Howland Carol A.; Groff Janet Y.; Mullen Patricia Dolan 《Canadian Metallurgical Quarterly》2003,48(3):182
Objective: To pilot test a health promotion intervention for women with physical disabilities. Design: Pre- and postintervention questionnaires. Participants: Two groups of women with physical disabilities (n=15). Intervention: Seven-session weekly workshop intervention grounded primarily in social-cognitive theory. Setting: Disability and rehabilitation settings. Main Outcome Measures: Indicators of health status. Results: Statistically significant positive changes between pre- and postintervention scores on measures of self-efficacy for dietary behaviors, medical decision making, social interaction, physical functioning, impact of physical limitation on role activities, and vitality. Conclusion: Women with disabilities who participate in this health promotion intervention may exhibit improvements on indicators of health status. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
50.