全文获取类型
收费全文 | 2856篇 |
免费 | 138篇 |
国内免费 | 12篇 |
专业分类
电工技术 | 30篇 |
化学工业 | 856篇 |
金属工艺 | 61篇 |
机械仪表 | 85篇 |
建筑科学 | 97篇 |
矿业工程 | 21篇 |
能源动力 | 88篇 |
轻工业 | 198篇 |
水利工程 | 21篇 |
石油天然气 | 8篇 |
武器工业 | 1篇 |
无线电 | 229篇 |
一般工业技术 | 566篇 |
冶金工业 | 209篇 |
原子能技术 | 38篇 |
自动化技术 | 498篇 |
出版年
2023年 | 34篇 |
2022年 | 123篇 |
2021年 | 120篇 |
2020年 | 90篇 |
2019年 | 66篇 |
2018年 | 100篇 |
2017年 | 104篇 |
2016年 | 104篇 |
2015年 | 94篇 |
2014年 | 131篇 |
2013年 | 216篇 |
2012年 | 163篇 |
2011年 | 194篇 |
2010年 | 139篇 |
2009年 | 129篇 |
2008年 | 141篇 |
2007年 | 107篇 |
2006年 | 94篇 |
2005年 | 86篇 |
2004年 | 60篇 |
2003年 | 62篇 |
2002年 | 49篇 |
2001年 | 33篇 |
2000年 | 31篇 |
1999年 | 29篇 |
1998年 | 54篇 |
1997年 | 35篇 |
1996年 | 30篇 |
1995年 | 31篇 |
1994年 | 24篇 |
1993年 | 26篇 |
1992年 | 16篇 |
1991年 | 20篇 |
1990年 | 14篇 |
1989年 | 13篇 |
1988年 | 11篇 |
1987年 | 24篇 |
1986年 | 16篇 |
1985年 | 15篇 |
1984年 | 13篇 |
1983年 | 11篇 |
1982年 | 16篇 |
1981年 | 11篇 |
1980年 | 9篇 |
1979年 | 11篇 |
1978年 | 13篇 |
1977年 | 9篇 |
1976年 | 10篇 |
1975年 | 9篇 |
1973年 | 15篇 |
排序方式: 共有3006条查询结果,搜索用时 15 毫秒
1.
2.
3.
Penedo Frank J.; Dahn Jason R.; Gonzalez Jeffrey S.; Molton Ivan; Carver Charles S.; Antoni Michael H.; Roos Bernard A.; Schneiderman Neil 《Canadian Metallurgical Quarterly》2003,22(2):220
This study evaluated relations among optimism, perceived stress management skills (PSMS), and positive mood in 46 men who had surgical treatment for localized prostate cancer. The authors found that optimism, PSMS, and positive mood scores were positively correlated. Positive mood was unrelated to demographic and disease-related control variables. In a hierarchical regression model controlling for PSMS, the relationship between optimism and positive mood became nonsignificant, whereas PSMS remained a correlate of positive mood. Results suggest that the relationship between optimism and positive mood may be mediated by belief in being able to use stress management techniques effectively. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
4.
5.
Ivan Fortelný Monika Lapčíková František Lednický Zdeněk Starý Zdeněk Kruliš 《Polymer Engineering and Science》2008,48(3):564-571
This article is focused on the phase structure development in immiscible polymer blends during melt mixing. Nonuniformity of the phase structure, i.e., the coexistence of areas containing particles with markedly different size distribution, was detected in quenched and compression molded samples of a number of various blends prepared by long and intensive mixing in the chamber of a Plasticorder. The same effect was found also for polystyrene/polyamide blends prepared in a twin‐screw extruder. It was shown that neglecting nonuniformity of the phase structure can lead to considerable error in evaluation of the effect of system parameters on the blend morphology. The reasons for the effect were discussed and it was found that inhomogeneous flow field in mixers is a plausible explanation of the nonuniform phase structure. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers 相似文献
6.
Iv?n Arce of Core Security Technologies looks at the current state of malware and introduces the articles he selected for this special issue. 相似文献
7.
8.
In the past few years many systems for learning decision rules from examples were developed. As different systems allow different types of answers when classifying new instances, it is difficult to appropriately evaluate the systems' classification power in comparison with other classification systems or in comparison with human experts. Classification accuracy is usually used as a measure of classification performance. This measure is, however, known to have several defects. A fair evaluation criterion should exclude the influence of the class probabilities which may enable a completely uninformed classifier to trivially achieve high classification accuracy. In this paper a method for evaluating the information score of a classifier's answers is proposed. It excludes the influence of prior probabilities, deals with various types of imperfect or probabilistic answers and can be used also for comparing the performance in different domains. 相似文献
9.
Ivan Hrivňák 《International Journal of Pressure Vessels and Piping》1985,20(3):223-237
This paper deals with the metallurgical changes which occur during heat treatment of welded joints. Stress relieving heat treatment in the temperature range below A1, the normalizing heat treatment and the heat treatment in the intercritical range A1–A3, are all considered. The thermal regime of welding is described. The practice of intercover of the weldment before applying PWHT to ambient temperature is described. It is stressed that the aim of stress-relieving heat treatment is not only to relax internal stresses but also to improve the microstructure and impact properties of HAZ and weld metal, to improve dimensional stability and increase resistance against stress corrosion. Examples are given of the effect of annealing in the intercritical range A1–A3 on the improvement in toughness of electroslag welded joints. Changes in dislocation distribution and density, precipitation processes and grain sizes during PWHT are described. 相似文献
10.
We present an Extended Quadratic Frobenius Primality Test (EQFT), which is related to the Miller-Rabin test and to several
other known probabilistic tests. EQFT takes time equivalent to about two or three Miller-Rabin tests, but has a much smaller
error probability, namely 256/331776t for t iterations of the test in the worst case. We also give bounds on the average-case behaviour of the test: consider
the algorithm that repeatedly chooses random odd k bit numbers, subjects them to t iterations of our test and outputs the
first one found that passes all tests. We obtain numeric upper bounds for the error probability of this algorithm as well
as a general closed expression bounding the error. For instance, it is at most 2-155 for k = 500, t = 2. Compared with earlier similar results for the Miller-Rabin test, the results indicate that our test in
the average case has the effect of nine Miller-Rabin tests. We also give bounds for the error in case a prime is sought by
incremental search from a random starting point. 相似文献