全文获取类型
收费全文 | 119651篇 |
免费 | 10073篇 |
国内免费 | 5343篇 |
专业分类
电工技术 | 7045篇 |
技术理论 | 5篇 |
综合类 | 7938篇 |
化学工业 | 19881篇 |
金属工艺 | 6930篇 |
机械仪表 | 7775篇 |
建筑科学 | 9140篇 |
矿业工程 | 3907篇 |
能源动力 | 3303篇 |
轻工业 | 7668篇 |
水利工程 | 2090篇 |
石油天然气 | 7709篇 |
武器工业 | 1035篇 |
无线电 | 13645篇 |
一般工业技术 | 14386篇 |
冶金工业 | 5602篇 |
原子能技术 | 1191篇 |
自动化技术 | 15817篇 |
出版年
2024年 | 586篇 |
2023年 | 2092篇 |
2022年 | 3501篇 |
2021年 | 4896篇 |
2020年 | 3825篇 |
2019年 | 3246篇 |
2018年 | 3556篇 |
2017年 | 3949篇 |
2016年 | 3501篇 |
2015年 | 4651篇 |
2014年 | 5861篇 |
2013年 | 6792篇 |
2012年 | 7519篇 |
2011年 | 8325篇 |
2010年 | 7053篇 |
2009年 | 6663篇 |
2008年 | 6500篇 |
2007年 | 6178篇 |
2006年 | 6634篇 |
2005年 | 5535篇 |
2004年 | 3901篇 |
2003年 | 3383篇 |
2002年 | 3160篇 |
2001年 | 2798篇 |
2000年 | 2818篇 |
1999年 | 3199篇 |
1998年 | 2764篇 |
1997年 | 2364篇 |
1996年 | 2117篇 |
1995年 | 1763篇 |
1994年 | 1488篇 |
1993年 | 1033篇 |
1992年 | 838篇 |
1991年 | 620篇 |
1990年 | 472篇 |
1989年 | 375篇 |
1988年 | 304篇 |
1987年 | 202篇 |
1986年 | 165篇 |
1985年 | 103篇 |
1984年 | 65篇 |
1983年 | 52篇 |
1982年 | 58篇 |
1981年 | 35篇 |
1980年 | 38篇 |
1979年 | 16篇 |
1978年 | 8篇 |
1977年 | 5篇 |
1976年 | 14篇 |
1975年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
Distributed Denial-of-Service (DDoS) attacks pose a serious threat to Internet security. Most current research focuses on
detection and prevention methods on the victim server or source side. To date, there has been no work on defenses using valuable
information from the innocent client whose IP has been used in attacking packets. In this paper, we propose a novel cooperative
system for producing warning of a DDoS attack. The system consists of a client detector and a server detector. The client
detector is placed on the innocent client side and uses a Bloom filter-based detection scheme to generate accurate detection
results yet consumes minimal storage and computational resources. The server detector can actively assist the warning process
by sending requests to innocent hosts. Simulation results show that the cooperative technique presented in this paper can
yield accurate DDoS alarms at an early stage. We theoretically show the false alarm probability of the detection scheme, which
is insensitive to false alarms when using specially designed evaluation functions.
This work is partially supported by HK Polyu ICRG A-PF86 and CERG Polyu 5196/04E, and by the National Natural Science Foundation
of China under Grant No. 90104005. 相似文献
132.
133.
用差热、热重法对原丝的热性能及由不同预处理方法所引起的PVA纤维的热行为变化进行了研究;并通过模拟脱水条件,用不同升温速率,求出了经不同预处理纤维的脱水反应活化能。结果表明,PVA原丝在230℃有一软化点,三种预处理都不同程度地影响了原丝的热效应变化;纤维在180~340℃主要为脱水反应;原丝及经脱水剂、O_3和O_3综合脱水剂处理的纤维,其脱水反应的表观活化能分别为:164.3kJ/mol,92.9kJ/mol,130.5kJ/mol和117.6kJ/mol。 相似文献
134.
135.
USM模块式家具源自于瑞士.钢制的球是USM家具的主要连接器。球和钢管的精密结合是USM品牌的独创,由此就可演变出不同规格.不同造型的USM家具。 相似文献
136.
Material removal and surface damage of Ti3SiC2 ceramic during electrical discharge machining (EDM) were investigated. Melting and decomposition were found to be the main material removal mechanisms during the machining process. Material removal rate was enhanced acceleratively with increasing discharge current, ie, working voltage, ui, but increased deceleratively with pulse duration, te. Microcracks in the surface and loose grains in the subsurface resulted from thermal shock were confirmed, and the surface damage in Ti3SiC2 ceramic led to a degradation of both strength and reliability. 相似文献
137.
138.
Hu P.J.-H. Tsang-Hsiang Cheng Chin-Ping Wei Chun-Hui Yu Chan A.L.F. Hue-Yu Wang 《IEEE transactions on systems, man, and cybernetics. Part A, Systems and humans : a publication of the IEEE Systems, Man, and Cybernetics Society》2007,37(4):481-492
Drug-related problems, particularly those that result from sub- or overtherapeutic doses of high-alert medications, have become a growing concern in clinical medicine. In this paper, we use a model-tree-based regression technique (namely, M5) and support vector machine (SVM) for regression to develop learning-based systems for predicting the adequacy of a vancomycin regimen. We empirically evaluate each system's accuracy in predicting patients' peak and trough concentrations in different clinical scenarios characterized by renal functions and regimen types. Our data consist of 1099 clinical cases that were collected from a major tertiary medical center in southern Taiwan. We also examine the use of bagging for enhancing the prediction power of the respective systems and include in our evaluation a salient one-compartment model for performance benchmark purposes. Overall, our evaluation results suggest that both M5 and SVM are significantly more accurate than the benchmark one-compartment model in predicting patients' peak and trough concentrations across all investigated clinical scenarios. M5 appears to benefit considerably from bagging, which has a positive but seemingly smaller effect on SVM. Taken together, our findings indicate supervised learning techniques that are capable of effectively supporting clinicians' use of vancomycin or similar high-alert drugs in their patient care and management. 相似文献
139.
针对W9Cr3M04V轧制成品材低倍碳化物剥落的形成原因分析,得出一次碳化物颗粒粗大、在1/4D至中心区域聚集是导致低倍热酸浸试验碳化物剥落的主因;由此进行冶炼过程中注速(锭形)、浇注温度选择对比工艺试验,得出在原有冶炼+轧制的工艺基础上选用2.2t锭、降低浇注温度(1489℃)能有效改善一次碳化物颗粒大小和聚集程度,进而有效降低低倍碳化物剥落倾向。 相似文献
140.