全文获取类型
收费全文 | 1455篇 |
免费 | 59篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 16篇 |
综合类 | 5篇 |
化学工业 | 355篇 |
金属工艺 | 26篇 |
机械仪表 | 35篇 |
建筑科学 | 22篇 |
能源动力 | 86篇 |
轻工业 | 95篇 |
水利工程 | 2篇 |
石油天然气 | 4篇 |
无线电 | 182篇 |
一般工业技术 | 299篇 |
冶金工业 | 167篇 |
原子能技术 | 14篇 |
自动化技术 | 207篇 |
出版年
2023年 | 23篇 |
2022年 | 53篇 |
2021年 | 52篇 |
2020年 | 53篇 |
2019年 | 48篇 |
2018年 | 69篇 |
2017年 | 56篇 |
2016年 | 65篇 |
2015年 | 31篇 |
2014年 | 44篇 |
2013年 | 136篇 |
2012年 | 59篇 |
2011年 | 61篇 |
2010年 | 63篇 |
2009年 | 61篇 |
2008年 | 38篇 |
2007年 | 38篇 |
2006年 | 47篇 |
2005年 | 26篇 |
2004年 | 24篇 |
2003年 | 25篇 |
2002年 | 16篇 |
2001年 | 10篇 |
2000年 | 21篇 |
1999年 | 17篇 |
1998年 | 38篇 |
1997年 | 24篇 |
1996年 | 38篇 |
1995年 | 15篇 |
1994年 | 19篇 |
1993年 | 23篇 |
1992年 | 18篇 |
1991年 | 11篇 |
1990年 | 11篇 |
1989年 | 11篇 |
1988年 | 11篇 |
1987年 | 9篇 |
1986年 | 8篇 |
1985年 | 14篇 |
1984年 | 12篇 |
1983年 | 13篇 |
1982年 | 10篇 |
1981年 | 8篇 |
1980年 | 17篇 |
1979年 | 14篇 |
1978年 | 12篇 |
1977年 | 9篇 |
1976年 | 11篇 |
1975年 | 7篇 |
1974年 | 5篇 |
排序方式: 共有1515条查询结果,搜索用时 24 毫秒
41.
42.
Lu Y. Abdelzaher T.F. Avneesh Saxena 《Parallel and Distributed Systems, IEEE Transactions on》2004,15(5):440-452
With the dramatic explosion of online information, the Internet is undergoing a transition from a data communication infrastructure to a global information utility. PDAs, wireless phones, Web-enabled vehicles, modem PCs, and high-end workstations can be viewed as appliances that "plug-in" to this utility for information. The increasing diversity of such appliances calls for an architecture for performance differentiation of information access. The key performance accelerator on the Internet is the caching and content distribution infrastructure. While many research efforts addressed performance differentiation in the network and on Web servers, providing multiple levels of service in the caching system has received much less attention. It has two main contributions. First, we describe, implement, and evaluate an architecture for differentiated content caching services as a key element of the Internet content distribution architecture. Second, we describe a control-theoretical approach that lays well-understood theoretical foundations for resource management to achieve performance differentiation in proxy caches. An experimental study using the Squid proxy cache shows that differentiated caching services provide significantly better performance to the premium content classes. 相似文献
43.
Sachin Bhalekar 《Signal, Image and Video Processing》2014,8(4):635-639
Differential-difference equations with multiple delays have applications in a variety of applied fields. We propose a prototype delay model introduced by Uçar involving two delays. Sufficient conditions for the stability of the model are given and used to study chaos. It is observed first time in the literature that the Uçar system shows not only two-scroll but also one-scroll chaotic attractors. 相似文献
44.
Sumit K. Mishra Nabanita Saha S. Singh Chhemendra Sharma M. V. S. N. Prasad Sachin Gautam Amit Misra Abhishek Gaur Deepika Bhattu Subhasish Ghosh Anubhav Dwivedi Rosalin Dalai Debajyoti Paul Tarun Gupta Sachchida N. Tripathi R. K. Kotnala 《Mapan》2017,32(3):229-241
Estimation of the direct radiative forcing (DRF) by atmospheric particles is uncertain to a large extent owing to uncertainties in their morphology (shape and size), mixing states, and chemical composition. A region-specific database of the aforementioned physico-chemical properties (at individual particle level) is necessary to improve numerically-estimated optical and radiative properties. Till date, there is no detailed observation of the above mentioned properties over Kanpur in the Indo-Gangetic Plain (IGP). To fill this gap, an experiment was carried out at Kanpur (IITK; 26.52°N, 80.23°E, 142 m msl), India from April to July, 2011. Particle types broadly classified as (a) Cu-rich particles mixed with carbon and sulphur (b) dust and clays mixed with carbonaceous species (c) Fe-rich particles mixed with carbon and sulfur and (d) calcite (CaCO3) particles aged with nitrate, were observed. The frequency distributions of aspect ratio (AR; indicator of extent of particle non-sphericity) of total 708 particles from April to June reveal that particles with aspect ratio range >1.2 to ≤1.4 were abundant throughout the experiment except during June when it was found to shift to high AR range, >1.4 to ≤1.6 (followed with another peak of AR i.e. >2 to ≤2.4) due to dust storm conditions enhancing the occurrence of more non-spherical particles over the sampling site. The spherical particles (and close to spherical shape; AR range, 1.0 to ≤1.2) were found to be <20% throughout the experiment with a minimum (11.5%) during June. Consideration of Homogeneous Equivalent Sphere Approximation (HESA) in the optical/radiative model over the study region is found to be irrelevant during the campaign. 相似文献
45.
46.
Interfacial tension of drugs with hydrophilic polymer (A) embedded gold resulting into selective drug adsorption, which also affected the drug adsorption kinetics. Two-dimensional crosslinked polymer embedded gold was synthesized for drug loading application in an acidic buffer. Lower interfacial tension of pantoprazole sodium (B) revealed the exponential loading inversely loading was gradual for chloroquine (C) having more interfacial tension with adsorbent. Initial 2 h was the exponential adsorption period for a pantoprazole sodium whereas exponential adsorption begins after 12 h for a chloroquine. Monolayer drug adsorption was obtained because Langmuir adsorption isotherm was obeyed by both drugs. Moreover, pseudo first- and pseudo second-order kinetics was also evaluated which demonstrated that reactive sites of the adsorbent are homogeneous and drug adsorption mechanism is chemisorption and not the physisorption. Thermal analysis was evaluated to confirm the polymer thermostability and glass transition temperature during catalytic applications in thermal reactions. 相似文献
47.
Sachin Patil Yi Yang Tay Farzad Baratzadeh Hamid Lankarani 《Journal of Mechanical Science and Technology》2017,31(7):3225-3232
Ever increasing requirements regarding vehicle safety have led to rapid developments in various joining process. Among FSW widely used for Aluminum alloy welded structure of car body because of their remarkable performance in welding. For a better understanding of this performance, it is necessary to determine the behavior of butt weld in service conditions. In earlier phase of this study, thermo mechanical simulations and analysis are performed to understand the thermal behavior in the FSW weld zones. The developed models are correlated against published experimental results in terms of temperature profile of the weld zone. The objectives of the second part of this work is to develop and demonstrate an FE model of bumper and crash box assembly that would improve on the current modeling techniques for the mechanical response of welds in structural problems. 相似文献
48.
49.
Amit K. Jaiswal Hemlata Chhabra Sachin S. Kadam Kishore Londhe Vivek P. Soni Jayesh R. Bellare 《Materials science & engineering. C, Materials for biological applications》2013,33(5):2926-2936
The aim of this study was to compare physico-chemical and biological properties of hydroxyapatite (HA) and hardystonite (HS) based composite scaffolds. Hardystonite (Ca2ZnSi2O7) powders were synthesized by a sol–gel method while polycaprolactone–hardystonite (PCL–HS) and polycaprolactone–hydroxyapatite (PCL–HA) were fabricated in nanofibrous form by electrospinning. The physico-chemical and biological properties such as tensile strength, cell proliferation, cell infiltration and alkaline phosphatase activity were determined on both kinds of scaffolds. We found that PCL–HS scaffolds had better mechanical strength compared to PCL–HA scaffolds. Addition of HA and HS particles to PCL did not show any inhibitory effect on blood biocompatibility of scaffolds when assessed by hemolysis assay. The in vitro cellular behavior was evaluated by growing murine adipose-tissue-derived stem cells (mE-ASCs) over the scaffolds. Enhanced cell proliferation and improved cellular infiltrations on PCL–HS scaffolds were observed when compared to HA containing scaffolds. PCL–HS scaffolds exhibited a significant increase in alkaline phosphatase (ALP) activity and better mineralization of the matrix in comparison to PCL–HA scaffolds. These results clearly demonstrate the stimulatory role of Zn and Si present in HS based composite scaffolds, suggesting their potential application for bone tissue engineering. 相似文献
50.
Design and development of guided four beam cantilever type MEMS based piezoelectric energy harvester
Microsystem Technologies - MEMS devices have found applicability in remote area of operation such as temperature monitoring in extreme climates, structural health monitoring, and car tire pressure... 相似文献