全文获取类型
收费全文 | 530篇 |
免费 | 16篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 2篇 |
化学工业 | 73篇 |
机械仪表 | 9篇 |
建筑科学 | 12篇 |
矿业工程 | 62篇 |
能源动力 | 29篇 |
轻工业 | 28篇 |
水利工程 | 6篇 |
石油天然气 | 9篇 |
无线电 | 42篇 |
一般工业技术 | 62篇 |
冶金工业 | 169篇 |
原子能技术 | 2篇 |
自动化技术 | 43篇 |
出版年
2024年 | 2篇 |
2023年 | 3篇 |
2022年 | 11篇 |
2021年 | 13篇 |
2020年 | 12篇 |
2019年 | 13篇 |
2018年 | 17篇 |
2017年 | 13篇 |
2016年 | 17篇 |
2015年 | 13篇 |
2014年 | 19篇 |
2013年 | 28篇 |
2012年 | 22篇 |
2011年 | 31篇 |
2010年 | 20篇 |
2009年 | 16篇 |
2008年 | 24篇 |
2007年 | 12篇 |
2006年 | 15篇 |
2005年 | 9篇 |
2004年 | 8篇 |
2003年 | 9篇 |
2002年 | 10篇 |
2001年 | 6篇 |
2000年 | 14篇 |
1999年 | 9篇 |
1998年 | 21篇 |
1997年 | 21篇 |
1996年 | 13篇 |
1995年 | 13篇 |
1994年 | 6篇 |
1993年 | 11篇 |
1992年 | 6篇 |
1991年 | 3篇 |
1990年 | 11篇 |
1989年 | 8篇 |
1988年 | 10篇 |
1987年 | 8篇 |
1986年 | 4篇 |
1985年 | 4篇 |
1984年 | 3篇 |
1983年 | 6篇 |
1982年 | 7篇 |
1980年 | 3篇 |
1977年 | 6篇 |
1976年 | 8篇 |
1975年 | 3篇 |
1970年 | 1篇 |
1969年 | 1篇 |
1966年 | 1篇 |
排序方式: 共有548条查询结果,搜索用时 281 毫秒
1.
Microsystem Technologies - The purpose of the present enquiry is to analyse the mechanics of an incompressible fluid, with water as base fluid, through a radially symmetric plumb duct with... 相似文献
2.
Amines such as dopamine, norepinephrine and epinephrine were analysed in the brain regions of O.mossambicus exposed to quinalphos, phenthoate and their combination for 96 hr. The three types of treatments significantly (P < 0.05) altered the amines level at various intervals in the brain regions. 相似文献
3.
D Levine PD Barnes S Sher RC Semelka W Li CR McArdle S Worawattanakul RR Edelman 《Canadian Metallurgical Quarterly》1998,206(2):549-554
PURPOSE: To evaluate the normal appearance of fetal anatomy, the conspicuity of fetal organs, the reproducibility of images, and the limitations to image quality with the use of half-Fourier, single-shot rapid acquisition with relaxation enhancement (RARE) magnetic resonance (MR) imaging. MATERIALS AND METHODS: Fifty-four fetuses of 49 pregnancies underwent MR imaging with the half-Fourier, single-shot RARE technique. Two reviewers attempted to identify 47 organs and anatomic regions in each fetus. Organ or region conspicuity, image quality, and the limitations of image quality were graded. RESULTS: Fetal anatomy was well depicted in fetuses over 20 weeks in gestational age. Fetal imaging was limited by gestational age of 20 weeks or less usually owing to the small size of the organ or region being evaluated and, less frequently, by motion. CONCLUSION: Half-Fourier, single-shot RARE MR imaging provided a detailed and reproducible evaluation of normal fetal anatomy, which can be used as a standard of reference in MR imaging of fetal anomalies. 相似文献
4.
5.
The change of foot length and width with age has been reported in a few anthropometric studies in the literature. However, the relationship with body height rarely is reported, and the dynamic effect of weightbearing on foot size has not been documented. In this series, 2829 children 3 to 18 years of age of equal gender distribution were included in the study. The foot length and width on weightbearing and nonweightbearing were measured with a special precision electronic caliper. The foot length and width were found to increase linearly from the age of 3 years until 12 years in girls and 15 years in boys. This was followed by a phase during which the increase plateaued. The foot length and width increased significantly on weightbearing at all ages in both genders with a mean of 2.1 to 4.4 mm or 3.1% to 4.8%, respectively. The foot length and width also were found to correlate significantly with the body height in both genders, with a correlation coefficient of 0.96 to 0.98. No significant differences were found between the sizes of the dominant and nondominant foot in either gender. 相似文献
6.
Kannapiran Nagarajan Muthusamy Athianna Meena Sher Singh 《Journal of Inorganic and Organometallic Polymers and Materials》2021,31(8):3441-3459
Journal of Inorganic and Organometallic Polymers and Materials - Different concentrations of ZnFe2O4 and manganese substituted ZnFe2O4 nanoparticles (10%, 20% and 30%) dispersed... 相似文献
7.
Adnan Abid Naveed Hussain Kamran Abid Farooq Ahmad Muhammad Shoaib Farooq Uzma Farooq Sher Afzal Khan Yaser Daanial Khan Muhammad Azhar Naeem Nabeel Sabir 《Neural computing & applications》2016,27(5):1207-1229
The quantity of information placed on the web has been greater than before and is increasing rapidly day by day. Searching through the huge amount of data and finding the most relevant and useful result set involves searching, ranking, and presenting the results. Most of the users probe into the top few results and neglect the rest. In order to increase user’s satisfaction, the presented result set should not only be relevant to the search topic, but should also present a variety of perspectives, that is, the results should be different from one another. The effectiveness of web search and the satisfaction of users can be enhanced through providing various results of a search query in a certain order of relevance and concern. The technique used to avoid presenting similar, though relevant, results to the user is known as a diversification of search results. This article presents a survey of the approaches used for search result diversification. To this end, this article not only provides a technical survey of existing diversification techniques, but also presents a taxonomy of diversification algorithms with respect to the types of search queries. 相似文献
8.
Wireless video sensor networks (WVSNs) have drawn significant attention in recent years due to the advent of low-cost miniaturized cameras, which makes it feasible to realize large-scale WVSNs for a variety of applications including security surveillance, environmental tracking, and health monitoring. However, the conventional video coding paradigms are not suitable for WVSNs due to resource constraints such as limited computation power, battery energy, and network bandwidth. In this paper, we evaluated and analyzed the performance of video codecs based on emerging video coding paradigms such as distributed video coding and distributed compressive video sensing for multihop WVSNs. The main objective of this work was to provide an insight into the computational (encoding/decoding) complexity, energy consumption, node and network lifetime, processing and memory requirements, and the quality of reconstruction of these video codecs. Based on the findings, this paper also provides some guidelines for the selection of appropriate video codecs for a given WVSN application. 相似文献
9.
The purpose of this study was to investigate and treat a group of patients referred for "idiopathic" infertility in whom no apparent cause for infertility, apart from inadequate cervical mucus, was found. Hormone investigations revealed that these patients could be divided into two groups: those with low sex steroid profiles despite apparent ovulation, and a second group with normal sex steroid profiles. All patients were treated with ovulation-inducing agents in an attempt to produce "controlled" ovarian hyperstimulation and an improved cervical mucus. Four of six patients conceived. The rationale behind the use of ovulation-inducing agents in this situation is discussed. 相似文献
10.
In a nonclinical sample of 395 young adults, the authors evaluated the relations between major personality traits, Diagnostic and Statistical Manual of Mental Disorders (4th ed.; DSM-IV; American Psychiatric Association, 1994) personality disorder symptoms, and DSM-IV alcohol use disorders (AUDs). Consistent with previous findings, traits related to disinhibition and negative affectivity were consistently associated with AUDs, as were Cluster B personality disorder symptoms (especially antisocial and borderline disorder symptoms). Multivariate analyses revealed that Cluster B symptoms were significantly associated with AUDs above and beyond what was accounted for by personality traits. Further, the authors found differential patterns of relations between other substance use disorders (SUDs; i.e., tobacco dependence and drug use diagnoses) and personality disorder symptoms. Overall, these results suggest that personality disorder symptoms predict unique variance in SUDs that reflect maladaptive aspects of personality traits. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献