全文获取类型
收费全文 | 4908篇 |
免费 | 137篇 |
国内免费 | 10篇 |
专业分类
电工技术 | 56篇 |
综合类 | 6篇 |
化学工业 | 899篇 |
金属工艺 | 74篇 |
机械仪表 | 81篇 |
建筑科学 | 273篇 |
矿业工程 | 21篇 |
能源动力 | 99篇 |
轻工业 | 237篇 |
水利工程 | 41篇 |
石油天然气 | 50篇 |
无线电 | 599篇 |
一般工业技术 | 729篇 |
冶金工业 | 1169篇 |
原子能技术 | 24篇 |
自动化技术 | 697篇 |
出版年
2022年 | 42篇 |
2021年 | 62篇 |
2020年 | 39篇 |
2019年 | 57篇 |
2018年 | 63篇 |
2017年 | 90篇 |
2016年 | 81篇 |
2015年 | 69篇 |
2014年 | 86篇 |
2013年 | 266篇 |
2012年 | 130篇 |
2011年 | 199篇 |
2010年 | 136篇 |
2009年 | 173篇 |
2008年 | 199篇 |
2007年 | 202篇 |
2006年 | 178篇 |
2005年 | 182篇 |
2004年 | 134篇 |
2003年 | 147篇 |
2002年 | 142篇 |
2001年 | 127篇 |
2000年 | 94篇 |
1999年 | 116篇 |
1998年 | 250篇 |
1997年 | 149篇 |
1996年 | 126篇 |
1995年 | 88篇 |
1994年 | 69篇 |
1993年 | 74篇 |
1992年 | 77篇 |
1991年 | 63篇 |
1990年 | 72篇 |
1989年 | 69篇 |
1988年 | 59篇 |
1987年 | 64篇 |
1986年 | 46篇 |
1985年 | 59篇 |
1984年 | 48篇 |
1983年 | 50篇 |
1982年 | 56篇 |
1981年 | 43篇 |
1980年 | 41篇 |
1979年 | 42篇 |
1978年 | 36篇 |
1977年 | 38篇 |
1976年 | 67篇 |
1975年 | 35篇 |
1974年 | 36篇 |
1973年 | 45篇 |
排序方式: 共有5055条查询结果,搜索用时 15 毫秒
1.
2.
Cerebral microbleeds and cognitive decline in a hemodialysis patient: Case report and review of literature
下载免费PDF全文
![点击此处可从《Hemodialysis international. International Symposium on Home Hemodialysis》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Lin Li Mark Fisher Wei‐Ling Lau Hamid Moradi Alexander Cheung Gaby Thai Jason Handwerker Kamyar Kalantar‐Zadeh 《Hemodialysis international. International Symposium on Home Hemodialysis》2015,19(3):E1-E7
Cerebral microbleeds (CMBs) are small hemosiderin deposits indicative of prior cerebral microscopic hemorrhage and previously thought to be clinically silent. Recent population‐based cross‐sectional studies and prospective longitudinal cohort studies have revealed association between CMB and cognitive dysfunction. In the general population, CMBs are associated with age, hypertension, and cerebral amyloid angiopathy. In the chronic kidney disease (CKD) population, diminished estimated glomerular filtration rate has been found to be an independent risk factor for CMB, raising the possibility that a uremic milieu may predispose to microbleeds. In the end‐stage renal disease (ESRD) population on hemodialysis, the incidence of microbleeds is significantly higher compared with a control group without history of CKD or stroke. We present an ESRD patient on chronic hemodialysis with a history of gradual cognitive decline and progressive CMBs. Through this case and literature review, we illustrate the need to develop detection and prediction models to treat this frequent development in ESRD patients. 相似文献
3.
4.
A Distributed Virtual Environment (DVE) system offers a computer-generated virtual world in which individuals located at different
places in the physical world can interact with one another. In order to achieve real-time response for a large user base,
DVE systems need to have a scalable architecture. In this paper, we present the design of a grid-enabled service oriented
framework for facilitating the construction of scalable DVE systems on computing grids. A service component called “gamelet”
is proposed, whose distinctive mark is its high mobility for supporting dynamic load sharing. We propose a gamelet migration
protocol which can ensure the transparency and efficiency of gamelet migration, and an adaptive gamelet load-balancing (AGLB)
algorithm for making gamelet redistribution decisions at runtime. The algorithm considers both the synchronization costs of
the DVE system and network latencies inherent in the grid nodes. The activities of the users and the heterogeneity of grid
resources are also considered in order to carry out load sharing more effectively. We evaluate the performance of the proposed
mechanisms through a multiplayer online game prototype implemented using the Globus toolkit. The results show that our approach
can achieve faster response times and higher throughputs than some existing approaches.
This research is supported in part by the China National Grid project (863 program) and the HKU Foundation Seed Grant 28506002. 相似文献
5.
The current Internet and wireless networks are harsh environments for transporting high-bandwidth multimedia data. We examine the technical issues involved, and describe an end-to-end solution to support a Web-based learn-on-demand system that operates in a wireless campus environment. 相似文献
6.
Systematic assessment of anger among people with developmental disabilities has been lacking, especially for hospital inpatients. Reliability and validity of anger self-report psychometric scales were investigated with 129 male patients, mostly forensic. Anger prevalence and its relationship to demographic, cognitive, and personality variables and to hospital assaultive behavior were examined. High internal and intermeasure consistency, and some concurrent validity with staff ratings, were found. Retrospective validity regarding physically assaultive behavior in the hospital was obtained. Hierarchical regressions revealed that patient-reported anger was a significant predictor of assaults postadmission, controlling for age, length of stay, IQ, violence offense history, and personality variables. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
7.
Hannes Verlinde Martine De Cock Raymond Boute 《IEEE transactions on systems, man, and cybernetics. Part B, Cybernetics》2006,36(3):679-684
As opposed to quantitative association rule mining, fuzzy association rule mining is said to prevent the overestimation of boundary cases, as can be shown by small examples. Rule mining, however, becomes interesting in large databases, where the problem of boundary cases is less apparent and can be further suppressed by using sensible partitioning methods. A data-driven approach is used to investigate if there is a significant difference between quantitative and fuzzy association rules in large databases. The influence of the choice of a particular triangular norm in this respect is also examined. 相似文献
8.
Values of D0 /δ and Q for grain-boundary diffusion, derived from published studies of normal grain growth in Al2 O3 , BeO, CaO, MgO, SiO2 , and CaSiO3 , are fit by the linear compensation equation log D0 /δ=0.03170Q -7.6792 (r2 =0.9384). Comparison of grain-boundary diffusion coefficients derived from grain growth in oxides with those obtained by direct experimental measurement suggests that the kinetics of normal grain growth are controlled by grain-boundary diffusion of oxygen. 相似文献
9.
On the macroscopic optimization of multicell wireless systems with multiuser detection and multiple antennas - uplink analysis 总被引:1,自引:0,他引:1
In this paper, we consider a system with K single-antenna client users, n/sub B/ base stations (each base station has n/sub R/ antennas), as well as a centralized controller. A client user could be associated with a single base station at any time. All the base stations operate at the same frequency and have optimal multiuser detection per base station which cancels intracell interference only. We consider a general problem of uplink macroscopic resource management where the centralized controller dynamically determines an appropriate association mapping of the K users with respect to the n/sub B/ base stations over a macroscopic time scale. We propose a novel analytical framework for the above macroscopic scheduling problems. A simple rule is to associate a user with the strongest base station (camp-on-the-strongest-cell), and this has been widely employed in conventional cellular systems. However, based on the optimization framework, we found that this conventional approach is in fact not optimal when multiuser detection is employed at the base station. We show that the optimal macroscopic scheduling algorithm is of exponential complexity, and we propose a simple greedy algorithm as a feasible solution. 相似文献
10.
In this paper we shall review the main appraches to nonmonotonic reasoning which we classify from the perspective of their underlying logical settings as classical, intuitionistic, three-valued/partial models, and conditional. We shall be placing special emphasis on some of the prominent approaches. We shall also give hints on potential future directions and emphasize that more theoretical work is still needed before a move to application is made. 相似文献