全文获取类型
收费全文 | 3049篇 |
免费 | 101篇 |
国内免费 | 46篇 |
专业分类
电工技术 | 60篇 |
综合类 | 42篇 |
化学工业 | 332篇 |
金属工艺 | 68篇 |
机械仪表 | 44篇 |
建筑科学 | 70篇 |
矿业工程 | 12篇 |
能源动力 | 93篇 |
轻工业 | 206篇 |
水利工程 | 35篇 |
石油天然气 | 38篇 |
武器工业 | 7篇 |
无线电 | 125篇 |
一般工业技术 | 244篇 |
冶金工业 | 1600篇 |
原子能技术 | 30篇 |
自动化技术 | 190篇 |
出版年
2024年 | 5篇 |
2023年 | 29篇 |
2022年 | 41篇 |
2021年 | 64篇 |
2020年 | 36篇 |
2019年 | 51篇 |
2018年 | 73篇 |
2017年 | 64篇 |
2016年 | 61篇 |
2015年 | 52篇 |
2014年 | 68篇 |
2013年 | 127篇 |
2012年 | 86篇 |
2011年 | 141篇 |
2010年 | 96篇 |
2009年 | 74篇 |
2008年 | 85篇 |
2007年 | 73篇 |
2006年 | 56篇 |
2005年 | 67篇 |
2004年 | 41篇 |
2003年 | 24篇 |
2002年 | 32篇 |
2001年 | 25篇 |
2000年 | 28篇 |
1999年 | 39篇 |
1998年 | 471篇 |
1997年 | 275篇 |
1996年 | 178篇 |
1995年 | 108篇 |
1994年 | 89篇 |
1993年 | 86篇 |
1992年 | 17篇 |
1991年 | 24篇 |
1990年 | 22篇 |
1989年 | 32篇 |
1988年 | 34篇 |
1987年 | 17篇 |
1986年 | 15篇 |
1985年 | 17篇 |
1984年 | 6篇 |
1983年 | 9篇 |
1982年 | 10篇 |
1981年 | 14篇 |
1980年 | 18篇 |
1979年 | 4篇 |
1978年 | 5篇 |
1977年 | 62篇 |
1976年 | 120篇 |
1975年 | 5篇 |
排序方式: 共有3196条查询结果,搜索用时 15 毫秒
41.
42.
Lizards (Dipsosaurus dorsalis) were placed in a desertlike environment in which the ambient temperature (Ta) at night (1800-0600 h) was 12 degrees C and the day (0600-1800 h) Ta was between 30 and 55 degrees C depending on the location within the chamber. When dead Aeromonas hydrophila (4 X 10(9) organisms) was injected into nine lizards, an elevation in body temperature (Tb) of 2.7 degrees C was observed during the same day. On the day after bacterial injection the lizards' body temperatures averaged 41.6 degrees C, an increase of 4.2 degrees C over their control day Tb. Further investigations on the febrile response of D. dorsalis were conducted at the University of Wisconsin's Biotron, where there exists a simulated desert environment with the light intensity, temperature, and humidity closely parelleling a typical spring day in the southwestern desert of the United States (the natural habitat of Dipsosaurus). In this environment injection of dead bacteria into seven lizards led to an average febrile response of similar magnitude (Tb = 40.5 degrees C) but with a longer latency than that found at the University of Michigan. Injection of 13 lizards with live A. hydrophila (5 X 10(9) organism subcut.) in the simulated desert at Michigan led to a daytime fever averaging 2.3 degrees C (mean Tb = 40.6 degrees C) over a 5-day period. During the 6th and 7th day the lizards' body temperature returned to the normal or afebrile level. Injections of sodium salicylate along with dead A. hydrophila resulted in a dose-dependent attenuation of the febrile response. These results demonstrate that the reptilian febrile response is strikingly similar to avian and mammalian fever and suggest a common origin and perhaps function for the febrile mechanism. 相似文献
43.
44.
S Bharati HA McAllister CJ Tatooles RA Miller M Weinberg HG Bucheleres M Lev 《Canadian Metallurgical Quarterly》1976,72(3):383-400
In the anatomy of 416 hearts, the seat of tricuspid stenosis or atresia is examined, with special reference to Fontan-like surgical procedures. A classification is offered which includes cases with and without regular or inverted transposition, and with decreased or increased pulmonary flow. The size and thickness of the right atrium, the size and architecture of the right ventricle, the size of the pulmonary tree, the types of atrial and ventricular septal defects, the condition of the mitral valve, and the size and thickness of the left atrium and left ventricle are analyzed. In addition the various intracardiac and extracardiac abnormalities are enumerated. Reference is also made to the tendency of the aorta and pulmonary trunk to override the septum, in some cases producing double-outlet left ventricle. It is considered that many cases of tricuspid valve atresia and stenosis with or without transposition may be amenable to Fontan-like procedures in the proper age group. All the above anatomic considerations have a bearing on the suitability and type of operative tricuspid bypass procedures, and they may influence the prognosis of surgical therapy. 相似文献
45.
AG Velasco FL Caparó Ldel A Hoyos MM Malqui HA Espinoza A Chahud 《Canadian Metallurgical Quarterly》1976,61(6-7):361-362
The catheter is based on the principle of compression and tamponage, assuring and guaranteeing hemostasis at the base of the ulcer. This method is suitable for permanently controlling an acute hemorrhage in the event medical treatment fails and surgery is contraindicated. Emergency surgery is changed to elective surgery with all its advantages. 相似文献
46.
47.
48.
49.
50.