全文获取类型
收费全文 | 3498篇 |
免费 | 108篇 |
国内免费 | 56篇 |
专业分类
电工技术 | 113篇 |
技术理论 | 1篇 |
综合类 | 91篇 |
化学工业 | 214篇 |
金属工艺 | 54篇 |
机械仪表 | 161篇 |
建筑科学 | 127篇 |
矿业工程 | 17篇 |
能源动力 | 54篇 |
轻工业 | 94篇 |
水利工程 | 24篇 |
石油天然气 | 52篇 |
武器工业 | 8篇 |
无线电 | 157篇 |
一般工业技术 | 245篇 |
冶金工业 | 2061篇 |
原子能技术 | 17篇 |
自动化技术 | 172篇 |
出版年
2024年 | 2篇 |
2023年 | 9篇 |
2022年 | 15篇 |
2021年 | 38篇 |
2020年 | 27篇 |
2019年 | 23篇 |
2018年 | 35篇 |
2017年 | 35篇 |
2016年 | 30篇 |
2015年 | 34篇 |
2014年 | 38篇 |
2013年 | 94篇 |
2012年 | 78篇 |
2011年 | 76篇 |
2010年 | 74篇 |
2009年 | 88篇 |
2008年 | 85篇 |
2007年 | 89篇 |
2006年 | 96篇 |
2005年 | 91篇 |
2004年 | 64篇 |
2003年 | 55篇 |
2002年 | 81篇 |
2001年 | 63篇 |
2000年 | 59篇 |
1999年 | 105篇 |
1998年 | 647篇 |
1997年 | 344篇 |
1996年 | 274篇 |
1995年 | 174篇 |
1994年 | 125篇 |
1993年 | 125篇 |
1992年 | 30篇 |
1991年 | 49篇 |
1990年 | 40篇 |
1989年 | 25篇 |
1988年 | 36篇 |
1987年 | 35篇 |
1986年 | 32篇 |
1985年 | 37篇 |
1982年 | 5篇 |
1981年 | 11篇 |
1980年 | 13篇 |
1979年 | 2篇 |
1978年 | 7篇 |
1977年 | 34篇 |
1976年 | 110篇 |
1975年 | 10篇 |
1973年 | 2篇 |
1971年 | 3篇 |
排序方式: 共有3662条查询结果,搜索用时 15 毫秒
1.
2.
3.
The case of a 36-year-old man who sought treatment of right facial myokymia and spastic paretic facial contracture is reported. Computed tomography and magnetic resonance imaging revealed a tumor located in the right cerebellar peduncle and the right dorsal pons bulging into the fourth ventricle. After microsurgical partial resection of the mass, which was verified histologically as an anaplastic glioma, facial myokymia initially ceased. The vermicular rippling movements were less intense upon recurrence and could be controlled by low-dose dexamethasone in the further course, when magnetic resonance imaging showed an interstitial pontine edema after percutaneous radiation therapy. It is assumed that facial myokymia and spastic paretic facial contracture were generated by ectopic activity due to alterations in the microenvironment at the intrapontine portion of the axons of the seventh nerve caused by the compressive effect of the tumor and later by edema. 相似文献
4.
Biodegradation of chlorpyrifos was studied in liquid culture media amended with either single or combined eight different plant pathogenic fungi isolated from the continuous cropping wheat fields. The average recovery of chlorpyrifos from the liquid media was found to be 86.1%. The detection limit of chlorpyrifos by the analytical method used was 19 ppb. Data showed that the growth of mixed fungi at concentrations up to 200 ppm of chlorpyrifos was higher than in the control treatment. Chlorpyrifos concentrations declined in the medium of combined fungi more than it did in the medium of any single fungus with increase in the incubation period. The amount of chlorpyrifos recovered was 79.8 ppm (39.9%) in the combined fungal cultures after 21 days. However, those recovered from the media of Fusarium graminearum, F. oxysporum, Rhizoctonia solani, Cladosporium cladosporiodes, Cephalosporium sp., Trichoderma viridi, Alternaria alternata, and Cladorrhinum brunnescens, ranged from 48.0 to 74.8%. The half-life value (T1/2) for chlorpyrifos was 15.8 day in the medium amended with mixed fungi. However, for the single cultures it ranged from 19.3 to 33.0 day. 相似文献
5.
6.
7.
Lie‐Fern Hsu 《Quality and Reliability Engineering International》2007,23(2):269-272
He and Grigoryan (Quality and Reliability Engineering International 2002; 18 :343–355) formulated the design of a double‐sampling (DS) s control chart as an optimization problem and solved it with a genetic algorithm. They concluded that the DS s control charts can be a more economically preferable alternative in detecting small shifts than traditional s control charts. We explain that, since they only considered the average sample size when the process is in control, their conclusion is questionable. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
8.
9.
An increasing amount of laser beam welded T‐joints (e.g. skin‐stringer) of aluminium alloys are now in use in advanced fuselage applications designed as ‘integral structures’ for weight and cost savings. It is known that weld joints generally show lower strength (undermatching) than base metal in both laser beam and friction stir welded joints of 6xxx series Al‐alloys. Damage tolerance considerations in terms of the residual strength of such joints require limit load solutions to be used in engineering fitness‐for‐service (FFS) analysis. The paper, therefore, provides an upper bound limit load solution in closed form for welded T‐joints (idealized) with strength undermatching and subject to a bending moment. In addition to the necessary requirements of the upper bound theorem, the kinematically admissible velocity field chosen leads to a stress field, which satisfies the equilibrium equations and some stress boundary conditions in the plastic zone. This is an advantage of the solution and, therefore, it is expected that the upper bound obtained is close to the exact limit load of such joints. 相似文献
10.
A 78-year-old Chinese woman presented with recurrent postprandial abdominal pain. Computerised tomography revealed a small bowel tumour causing volvulus of a segment of the small bowel. Laparotomy confirmed an extraluminal ileal tumour with partial volvulus of the involved small bowel segment. Small bowel resection was done. Histological and ultrastructural studies confirmed a gastrointestinal autonomic nerve tumour. We review the medical literature on this rare tumour. 相似文献