全文获取类型
收费全文 | 2810篇 |
免费 | 38篇 |
国内免费 | 9篇 |
专业分类
电工技术 | 41篇 |
综合类 | 1篇 |
化学工业 | 305篇 |
金属工艺 | 53篇 |
机械仪表 | 34篇 |
建筑科学 | 19篇 |
能源动力 | 80篇 |
轻工业 | 67篇 |
水利工程 | 17篇 |
石油天然气 | 5篇 |
无线电 | 275篇 |
一般工业技术 | 287篇 |
冶金工业 | 1470篇 |
原子能技术 | 13篇 |
自动化技术 | 190篇 |
出版年
2024年 | 5篇 |
2023年 | 22篇 |
2022年 | 35篇 |
2021年 | 53篇 |
2020年 | 33篇 |
2019年 | 36篇 |
2018年 | 47篇 |
2017年 | 37篇 |
2016年 | 47篇 |
2015年 | 19篇 |
2014年 | 61篇 |
2013年 | 77篇 |
2012年 | 70篇 |
2011年 | 75篇 |
2010年 | 67篇 |
2009年 | 71篇 |
2008年 | 58篇 |
2007年 | 60篇 |
2006年 | 36篇 |
2005年 | 37篇 |
2004年 | 36篇 |
2003年 | 43篇 |
2002年 | 32篇 |
2001年 | 31篇 |
2000年 | 23篇 |
1999年 | 45篇 |
1998年 | 396篇 |
1997年 | 253篇 |
1996年 | 159篇 |
1995年 | 104篇 |
1994年 | 101篇 |
1993年 | 95篇 |
1992年 | 38篇 |
1991年 | 48篇 |
1990年 | 39篇 |
1989年 | 50篇 |
1988年 | 28篇 |
1987年 | 43篇 |
1986年 | 31篇 |
1985年 | 37篇 |
1984年 | 24篇 |
1983年 | 17篇 |
1982年 | 31篇 |
1981年 | 14篇 |
1980年 | 23篇 |
1978年 | 10篇 |
1977年 | 45篇 |
1976年 | 89篇 |
1975年 | 5篇 |
1973年 | 7篇 |
排序方式: 共有2857条查询结果,搜索用时 15 毫秒
1.
Neural Processing Letters - The uncertainty caused mainly by the deficiency of precision and data, artificial/human-made errors, information accessed from expert opinions or very miniature size of... 相似文献
2.
3.
4.
S. Sarkar P. Mohan Raj S. Chakraborty G. Phanikumar K. Chattopadhyay P. Dutta 《Journal of Materials Science》2003,38(1):155-164
A three dimensional, transient model is developed for studying heat transfer, fluid flow and mass transfer for the case of a single-pass laser surface alloying process. The numerical study is performed in a co-ordinate system fixed to the laser which moves with a constant scanning speed. The coupled momentum, energy and species conservation equations are solved using a finite volume technique. Phase change processes are modelled using a fixed-grid enthalpy-porosity technique, which is capable of predicting the continuously evolving solid-liquid interface. The three-dimensional model is able to predict the species concentration distribution inside the molten pool during alloying, as well as in the entire cross section of the solidified alloy. Corresponding experimental results show a good qualitative agreement with the numerical predictions with regard to pool shape and final composition distribution. 相似文献
5.
6.
L Giorgi A Di Filippo A Franchini L Rizzo S Benvenuti M Conti GP Novelli 《Canadian Metallurgical Quarterly》1994,60(1-2):43-47
OBJECTIVE: The reflex response to orotracheal intubation provokes an increase of arterial pressure accompanied by an increase of chorioides volume and a consequent ocular hypertone. There are several methods to reduce the reflex response due to intubation. One of the most effective is topical anaesthesia of larynx and trachea. Experiments were directed to evaluate the efficacy of topical anaesthesia to reduce the intraocular hypertone due to orotracheal intubation. DESIGN: A prospective randomized mask study was conduct on patients undergoing ophthalmologic (anterior segment) surgery at the Eye Clinic of Florence University. METHODS: Intraocular pressure was measured by a Goldman tonometer at four times: T0 = basal, T1 = 2' minutes after induction of general anaesthesia, T2 = 2' minutes after laryngoscopy, T3 = 2' minutes after orotracheal intubation. At the same moments, systolic blood pressure, heart rate, rate pressure pro duct were measured. Patients were randomly divided in two groups: Group L (n = 10) in which was evaluated the efficacy of laryngotracheal topical spray of lidocaine 4% (2 ml) and Group F (n = 10) in which saline was used instead of anesthetic. The filling of the LTA kit (Abbott) was made by a person not involved in the experiments. DATA ANALYSIS: Student's t test for unpaired data. RESULTS: Topical anaesthesia reduces the increase of intraocular pressure, hypertension and rate pressure product due to intubation. The intraocular pressure reduces to 13% less than basal value in Group L and increase to 50% more than basal value in Group F. CONCLUSION: The topical anaesthesia of larynx and trachea is effective to reduce the intraocular hypertension due to the reflex response evoked by orotracheal intubation. 相似文献
7.
8.
AD Santin PL Hermonat JC Hiserodt J Fruehauf V Schranz D Barclay S Pecorelli GP Parham 《Canadian Metallurgical Quarterly》1997,64(3):477-480
Tumor cells from eight freshly isolated cervical cancers (i.e., four adenocarcinomas and four squamous carcinomas) were analyzed for their production of the immune-inhibitory cytokine transforming growth factor-beta (TGF-beta) in vitro. All fresh adenocarcinomas secreted significant levels of TGF-beta (mean 397, range between 207 and 782 pg/ml/10(5) cells/48 hr). In contrast, no detectable TGF-beta was present in the supernatants from the four fresh squamous carcinoma cultures (P < 0.001). These data suggest that major differences in the secretion of the immunoinhibitory cytokine TGF-beta exist between squamous cell carcinomas and adenocarcinomas of the uterine cervix. Furthermore, these findings suggest that at least some of the differences in the natural biologic behavior, as well as in the response to radiation treatment, between these two histologic types of cervical cancer could be related to differences in secretion of this immune-inhibitory cytokine. 相似文献
9.
Neog D.K. Pattnaik S.S. Panda D.C. Devi S. Khuntia B. Dutta M. 《Antennas and Propagation Magazine, IEEE》2005,47(3):60-65
This paper deals with the design of a multi-slot hole-coupled microstrip antenna on a substrate of 2 mm thickness that gives multi-frequency (wideband) characteristics. The Method of Moments (MoM)-based IE3D software was used to simulate the results for return loss, VSWR, the Smith chart, and the radiation patterns. A tunnel-based artificial neural network (ANN) was also developed to calculate the radiation patterns of the antenna. The radiation patterns were measured experimentally at 10.5 GHz and 12 GHz. The experimental results were in good agreement with the simulated results from IE3D and those of the artificial neural network. A new method of using a genetic algorithm (GA) in an artificial neural network is also discussed. This new method was used to calculate the resonant frequency of a single-shorting-post microstrip antenna. The resonant frequency calculated using the genetic-algorithm-coupled artificial neural network was compared with the analytical and experimental results. The results obtained were in very good agreement with the experimental results. 相似文献
10.
Densification of a-Sic powders with no premixed sintering aids (type 1) and with premixed B and C (type 2) was investigated by sintering them at 2150° to 2200°C for 30 min. Flexure strengths, Weibull moduli, and fracture flaws were characterized for type 2 α-SiC only. The results were compared with those for a state-of-the-art sintered a-Sic material. 相似文献