全文获取类型
收费全文 | 8954篇 |
免费 | 425篇 |
国内免费 | 92篇 |
专业分类
电工技术 | 202篇 |
综合类 | 92篇 |
化学工业 | 1631篇 |
金属工艺 | 222篇 |
机械仪表 | 313篇 |
建筑科学 | 364篇 |
矿业工程 | 15篇 |
能源动力 | 293篇 |
轻工业 | 463篇 |
水利工程 | 38篇 |
石油天然气 | 62篇 |
武器工业 | 2篇 |
无线电 | 1777篇 |
一般工业技术 | 1609篇 |
冶金工业 | 1215篇 |
原子能技术 | 89篇 |
自动化技术 | 1084篇 |
出版年
2023年 | 98篇 |
2022年 | 141篇 |
2021年 | 207篇 |
2020年 | 151篇 |
2019年 | 135篇 |
2018年 | 200篇 |
2017年 | 196篇 |
2016年 | 195篇 |
2015年 | 198篇 |
2014年 | 300篇 |
2013年 | 538篇 |
2012年 | 453篇 |
2011年 | 493篇 |
2010年 | 392篇 |
2009年 | 449篇 |
2008年 | 455篇 |
2007年 | 414篇 |
2006年 | 385篇 |
2005年 | 327篇 |
2004年 | 302篇 |
2003年 | 305篇 |
2002年 | 256篇 |
2001年 | 233篇 |
2000年 | 215篇 |
1999年 | 198篇 |
1998年 | 472篇 |
1997年 | 315篇 |
1996年 | 218篇 |
1995年 | 145篇 |
1994年 | 127篇 |
1993年 | 146篇 |
1992年 | 82篇 |
1991年 | 79篇 |
1990年 | 70篇 |
1989年 | 50篇 |
1988年 | 53篇 |
1987年 | 54篇 |
1986年 | 59篇 |
1985年 | 32篇 |
1984年 | 32篇 |
1983年 | 20篇 |
1981年 | 40篇 |
1980年 | 22篇 |
1979年 | 21篇 |
1978年 | 26篇 |
1977年 | 40篇 |
1976年 | 43篇 |
1975年 | 12篇 |
1974年 | 12篇 |
1971年 | 12篇 |
排序方式: 共有9471条查询结果,搜索用时 9 毫秒
71.
72.
Qin Li Chengqing Li Dongyang Long Wai Hong Chan Changji Wang 《Quantum Information Processing》2013,12(7):2427-2439
In this paper, an efficient arbitrated quantum signature scheme is proposed by combining quantum cryptographic techniques and some ideas in classical cryptography. In the presented scheme, the signatory and the receiver can share a long-term secret key with the arbitrator by utilizing the key together with a random number. While in previous quantum signature schemes, the key shared between the signatory and the arbitrator or between the receiver and the arbitrator could be used only once, and thus each time when a signatory needs to sign, the signatory and the receiver have to obtain a new key shared with the arbitrator through a quantum key distribution protocol. Detailed theoretical analysis shows that the proposed scheme is efficient and provably secure. 相似文献
73.
A review of smart homes- present state and future challenges 总被引:5,自引:0,他引:5
In the era of information technology, the elderly and disabled can be monitored with numerous intelligent devices. Sensors can be implanted into their home for continuous mobility assistance and non-obtrusive disease prevention. Modern sensor-embedded houses, or smart houses, cannot only assist people with reduced physical functions but help resolve the social isolation they face. They are capable of providing assistance without limiting or disturbing the resident's daily routine, giving him or her greater comfort, pleasure, and well-being. This article presents an international selection of leading smart home projects, as well as the associated technologies of wearable/implantable monitoring systems and assistive robotics. The latter are often designed as components of the larger smart home environment. The paper will conclude by discussing future challenges of the domain. 相似文献
74.
Lot streaming for product assembly in job shop environment 总被引:3,自引:1,他引:2
Assembly job shop scheduling problem (AJSP) is an extension of classical job shop scheduling problem (JSP). AJSP starts with JSP and appends an assembly stage to the completed jobs. Lot streaming (LS) technique is a process of splitting jobs into smaller sub-jobs such that successive operations can be overlapped. This paper combines, for the first time, LS and AJSP, extending LS applicability to both machining and assembly. To solve this complex problem, an efficient algorithm is proposed using genetic algorithms and simple dispatching rules. Experimental results suggest that equal size LS outperforms varied size LS with respect to the objective function. 相似文献
75.
The aim of our study was to further develop an understanding of social capital in organizational-knowledge-sharing. We first developed a measurement tool and then a theoretical framework in which three social capital factors (social network, social trust, and shared goals) were combined with the theory of reasoned action; their relationships were then examined using confirmatory factoring analysis. We then surveyed of 190 managers from Hong Kong firms, we confirm that a social network and shared goals significantly contributed to a person's volition to share knowledge, and directly contributed to the perceived social pressure of the organization. The social trust has however showed no direct effect on the attitude and subjective norm of sharing knowledge. 相似文献
76.
A Randomized Algorithm for Online Unit Clustering 总被引:1,自引:0,他引:1
In this paper, we consider the online version of the following problem: partition a set of input points into subsets, each enclosable by a unit ball, so as to minimize the number of subsets used. In the one-dimensional case, we show that surprisingly the naïve upper bound of 2 on the competitive ratio can be beaten: we present a new randomized 15/8-competitive online algorithm. We also provide some lower bounds and an extension to higher dimensions. 相似文献
77.
OY Chan 《Canadian Metallurgical Quarterly》1994,23(5):706-709
More than 200,000 persons in Singapore work shifts. Over half of these shiftworkers are females. With the continued emphasis on capital-intensive industries and growing demand for "round-the-clock" services, shiftwork is increasingly an economic necessity for more and more industries and a way of life for many Singaporeans. It is generally accepted that about 20% of those who start shiftwork may find it difficult to continue in such work, usually for social rather than medical reasons. For those who continue on shiftwork, concerns have been raised regarding possible health effects, such as increased incidence of digestive disorders and ulcers, chronic fatigue and cardiovascular disorders. In the case of female shiftworkers, there is also the concern that the added responsibilities of looking after the home and young children may further aggravate sleep problems associated with shiftwork, thus adversely affecting their health. So far, our own studies of female electronics workers on 8-hour as well as 12-hour shift schedules indicate no serious long-term health effects. The study subjects had been employed in such work for at least over a year, some as long as 17 years and 6 years, respectively. Except for complaints of sleep problems and tiredness among some rotating shiftworkers, no significant differences in symptom prevalence, blood pressure or sickness absence were found between the shift and day workers. While the findings are reassuring, further studies may be needed to determine if preventive measures can be taken to minimise the common complaints of sleep problems and tiredness, particularly among rotating shiftworkers. 相似文献
78.
Pattern Analysis and Applications - Both the multiple sources of the available in-the-wild datasets and noisy information of images lead to huge challenges for discriminating subtle distinctions... 相似文献
79.
Wu-Chiang Chan Ping-Chuan Chen Meng-Chin Tsai Ting-Ko Chen 《Engineering Management Journal; EMJ》2017,29(2):87-98
Open innovation has transformed internal novel resource allocation and facilitated diverse interorganizational cooperation models. Previous studies have investigated open innovation archetypes and their formation. However, most researchers have neglected the crucial role that team leaders play in integrating internal and external resources and connecting creative ideas in open innovation. This study investigated the influence of open innovation archetypes and team leaders’ innovation traits on team performance. On the basis of the literature review, the analytical hierarchy process was applied to construct a framework for assessing and selecting team leaders in open innovation. The analysis was completed based on samples from 45 valid respondents (88% return rate) in Taiwan’s high-tech industry. The study results suggested that innovation knowledge is the most crucial innovation criterion for a leader, particularly core knowledge and advanced knowledge. Among the various sub-criteria, extrinsic motivation was the second most important sub-criterion. Leaders with strong innovation motivations are suitable to lead inbound open innovation projects. 相似文献
80.
Joan C. Lo Gerald J. Beck George A. Kaysen Christopher T. Chan Alan S. Kliger Michael V. Rocco Glenn M. Chertow for the FHN Study 《Hemodialysis international. International Symposium on Home Hemodialysis》2017,21(2):190-196
Introduction: End‐stage renal disease is associated with elevations in circulating prolactin concentrations, but the association of prolactin concentrations with intermediate health outcomes and the effects of hemodialysis frequency on changes in serum prolactin have not been examined. Methods: The FHN Daily and Nocturnal Dialysis Trials compared the effects of conventional thrice weekly hemodialysis with in‐center daily hemodialysis (6 days/week) and nocturnal home hemodialysis (6 nights/week) over 12 months and obtained measures of health‐related quality of life, self‐reported physical function, mental health and cognition. Serum prolactin concentrations were measured at baseline and 12‐month follow‐up in 70% of the FHN Trial cohort to examine the associations among serum prolactin concentrations and physical, mental and cognitive function and the effects of hemodialysis frequency on serum prolactin. Findings: Among 177 Daily Trial and 60 Nocturnal Trial participants with baseline serum prolactin measurements, the median serum prolactin concentration was 65 ng/mL (25th–75th percentile 48–195 ng/mL) and 81% had serum prolactin concentrations >30 ng/mL. While serum prolactin was associated with sex (higher in women), we observed no association between baseline serum prolactin and age, dialysis vintage, and baseline measures of physical, mental and cognitive function. Furthermore, there was no significant effect of hemodialysis frequency on serum prolactin in either of the two trials. Discussion: Serum prolactin concentrations were elevated in the large majority of patients with ESRD, but were not associated with several measures of health status. Circulating prolactin levels also do not appear to decrease in response to more frequent hemodialysis over a one‐year period. 相似文献