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排序方式: 共有666条查询结果,搜索用时 265 毫秒
61.
Zhu Peining A. Sreekumaran Nair Yang Shengyuan Seeram Ramakrishna 《Materials Research Bulletin》2011,46(4):588-6548
Titanium dioxide (TiO2)-multiwalled carbon nanotube (MWCNT) nanocomposites with a novel morphology of rice-grains are prepared by electrospinning method. Anatase-MWCNT composites (with a negligibly small percentage of rutile and brookite) are obtained by high temperature sintering of the as-spun (polymer-TiO2-MWCNT) composite fibers. The nanocomposites are characterized using spectroscopy and microscopy. The results show that the functionalized MWCNTs are integrated into the TiO2 rice grain structures. The enhanced photocatalysis of the nanocomposites in comparison to TiO2 rice grains and commercially available P-25 is demonstrated in photodegradation of Alizarin Red dye. 相似文献
62.
Modulo scheduling is a framework within which algorithms for software pipelining innermost loops may be defined. The framework specifies a set of constraints that must be met in order to achieve a legal modulo schedule. A wide variety of algorithms and heuristics can be defined within this framework. Little work has been done to evaluate and compare alternative algorithms and heuristics for modulo scheduling from the viewpoints of schedule quality as well as computational complexity. This, along with a vague and unfounded perception that modulo scheduling is computationally expensive as well as difficult to implement, have inhibited its incorporation into product compilers. This paper presents iterative modulo scheduling, a practical algorithm that is capable of dealing with realistic machine models. The paper also characterizes the algorithm in terms of the quality of the generated schedules as well the computational expense incurred. 相似文献
63.
N Ramakrishna M Smedman V Ramakrishna B Gillam 《Canadian Metallurgical Quarterly》1997,231(3):615-618
We investigated the effects of beta-amyloid peptide precursor (APP) overexpression upon the levels of other mRNAs. Using quantitative slot-blot hybridization and immunoblot analysis we observed that enhanced levels of APP elevated the levels of beta-actin and beta-actin mRNA. Our results also suggest that the cytoplasmic domain of APP is crucial for the elevation in beta-actin gene expression. 相似文献
64.
QoS provisioning dynamic connection-admission control for multimedia wireless networks using a Hopfield neural network 总被引:3,自引:0,他引:3
This paper presents a quality-of-service (QoS) provisioning dynamic connection-admission control (CAC) algorithm for multimedia wireless networks. A multimedia connection consists of several substreams (i.e., service classes), each of which presets a range of feasible QoS levels (e.g., data rates). The proposed algorithm is mainly devoted to finding the best possible QoS levels for all the connections (i.e., QoS vector) that maximize resource utilization by fairly distributing wireless resources among the connections while maximizing the statistical multiplexing gain (i.e., minimizing the blocking and dropping probabilities). In the case of congestion (overload), the algorithm uniformly degrades the QoS levels of the existing connections (but only slightly) in order to spare some resources for serving new or handoff connections, thereby naturally minimizing the blocking and dropping probabilities (it amounts to maximizing the statistical multiplexing gain). The algorithm employs a Hopfield neural network (HNN) for finding a QoS vector. The problem itself is formulated as a multi-objective optimization problem. Hardware-based HNN exhibits high (computational) speed that permits real time running of the CAC algorithm. Simulation results show that the algorithm can maximize resource utilization and maintain fairness in resource sharing, while maximizing the statistical multiplexing gain in providing acceptable service grades. Furthermore, the results are relatively insensitive to handoff rates. 相似文献
65.
Pucha R.V. Hegde S. Damani M. Tunga K. Perkins A. Mahalingam S. Ramakrishna G. Lo G.C. Klein K. Ahmad J. Sitaraman S.K. 《Advanced Packaging, IEEE Transactions on》2004,27(2):438-452
The next-generation convergent microsystems, based on system-on-package (SOP) technology, require up-front system-level design-for-reliability approaches and appropriate reliability assessment methodologies to guarantee the reliability of digital, optical, and radio frequency (RF) functions, as well as their interfaces. Systems approach to reliability requires the development of: i) physics-based reliability models for various failure mechanisms associated with digital, optical, and RF Functions, and their interfaces in the system; ii) design optimization models for the selection of suitable materials and processing conditions for reliability, as well as functionality; and iii) system-level reliability models understanding the component and functional interaction. This paper presents the reliability assessment of digital, optical, and RF functions in SOP-based microsystems. Upfront physics-based design-for-reliability models for various functional failure mechanisms are presented to evaluate various design options and material selection even before the prototypes are made. Advanced modeling methodologies and algorithms to accommodate material length scale effects due to enhanced system integration and miniaturization are presented. System-level mixed-signal reliability is discussed thorough system-level reliability metrics relating component-level failure mechanisms to system-level signal integrity, as well as statistical aspects. 相似文献
66.
67.
KN Srinivasan KV Pugalendi G Sambandam M Ramakrishna Rao S Krishnan VP Menon 《Canadian Metallurgical Quarterly》1998,275(2):197-203
Between 1957 and 1993, the Siberian Chemical Complex (Tomsk-7) located in the Tomsk region (Russia) regularly discharged radioactive liquid wastes into the Tom River which resulted in an extensive contamination of large territories with long lived radionuclides such as cesium-137 and strontium-90. In the summers of 1996 and 1997, Research Team of Siberian Medical University conducted biodosimetry and cytogenetic monitoring of pikes (Esox lucius) caught in the Tom River at various distances downstream from the Siberian Chemical Complex (SCC) using the micronucleus test and the gamma spectroscopy. Our findings demonstrated that the difference in frequency of micronucleated erythrocytes between the radiation-exposed fish caught downstream from the SCC and the controls was statistically significant (P < 0.01). Moreover, we found a good correlation between radiocesium concentration and micronucleated erythrocyte frequency in pikes. It was found that both the micronucleated erythrocyte frequency in pike blood and the level of the pike radiocesium concentration depended on the age of pikes. The micronucleated erythrocyte frequency gradually increased from the 1-year-old pikes to the over 20-year-old pikes. On the other hand, the average level of radiocesium concentration gradually increased from the 1-year-old pikes only up to the 10-year-old pikes. There is no correlation between radiocesium concentration and micronucleated erythrocyte frequency in the over 10-year-old pikes. 相似文献
68.
69.
B. Kwatra L. D. Ahuja V. Ramakrishna 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1970,20(4):123-126
The settling of kaolin has been studied in various alcohol-benzene mixtures, under controlled moisture conditions. The influence of the parameters of the settling apparatus has been evaluated. From the log Q/?2 vs. ? plots, the average particle size has been calculated, and the effect of absorbed moisture and the nature of the solvent mixture on cluster formation have been discussed. The constants of Oliver's equation for these systems have been obtained and their significance in the light of Landel's theory has been discussed. 相似文献
70.
Determination of Coordinated Maintenance Scheduling Frequencies for a Group of Machines 总被引:1,自引:0,他引:1
An economic model of maintenance planning for a machine shop is developed. Maintenance can be performed on an individual machine or the entire group of machines simultaneously. The coordinated maintenance on the group would save on the fixed costs associated with separate overhauls. The frequencies of maintenance on each machine within two consecutive coordinated overhauls and the time between these coordinated overhauls is determined. The resulting model selects a solution that is close to the minimum of the total cost of production and maintenance. 相似文献