全文获取类型
收费全文 | 853篇 |
免费 | 50篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 5篇 |
综合类 | 2篇 |
化学工业 | 192篇 |
金属工艺 | 20篇 |
机械仪表 | 27篇 |
建筑科学 | 13篇 |
能源动力 | 35篇 |
轻工业 | 87篇 |
水利工程 | 10篇 |
石油天然气 | 1篇 |
无线电 | 112篇 |
一般工业技术 | 192篇 |
冶金工业 | 70篇 |
原子能技术 | 2篇 |
自动化技术 | 138篇 |
出版年
2024年 | 2篇 |
2023年 | 14篇 |
2022年 | 40篇 |
2021年 | 49篇 |
2020年 | 24篇 |
2019年 | 39篇 |
2018年 | 49篇 |
2017年 | 41篇 |
2016年 | 28篇 |
2015年 | 24篇 |
2014年 | 30篇 |
2013年 | 65篇 |
2012年 | 46篇 |
2011年 | 39篇 |
2010年 | 42篇 |
2009年 | 30篇 |
2008年 | 44篇 |
2007年 | 33篇 |
2006年 | 34篇 |
2005年 | 28篇 |
2004年 | 15篇 |
2003年 | 19篇 |
2002年 | 13篇 |
2001年 | 12篇 |
2000年 | 6篇 |
1999年 | 9篇 |
1998年 | 17篇 |
1997年 | 15篇 |
1996年 | 12篇 |
1995年 | 5篇 |
1994年 | 7篇 |
1993年 | 6篇 |
1992年 | 8篇 |
1991年 | 7篇 |
1990年 | 7篇 |
1989年 | 4篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 7篇 |
1983年 | 4篇 |
1982年 | 4篇 |
1981年 | 2篇 |
1979年 | 1篇 |
1978年 | 4篇 |
1977年 | 4篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1971年 | 2篇 |
1969年 | 3篇 |
排序方式: 共有906条查询结果,搜索用时 15 毫秒
861.
862.
MJ Marzullo AK Shetty 《Canadian Metallurgical Quarterly》1998,37(7):437; discussion: 437-437; discussion: 439
863.
LJ Hurley CR Burke SK Shetty SR Previte OE Sakr JA Libertino 《Canadian Metallurgical Quarterly》1996,47(4):596-598
We report the case of a 72-year-old man with bilateral testicular masses that, on histologic section, were found to be synchronous non-Hodgkin's lymphomas. Workup was negative for systemic disease, indicating the possibility of bilateral primary testicular lymphomas. We discuss the evaluation and treatment of this lesion and review the literature concerning this subject. 相似文献
864.
Functional recovery observed in Parkinson's disease patients following grafting of fetal substantia nigra has encouraged the development of similar grafting therapy for other neurological disorders. Fetal hippocampal grafting paradigms are of considerable significance because of their potential to treat neurological disorders affecting primarily hippocampus, including temporal lobe epilepsy, cerebral ischemia, stroke, and head injury. Since many recent studies of hippocampal transplants were carried out with an aim of laying the foundation for future clinical applications, an overview of the development of fetal hippocampal transplants, and their capability for inducing functional recovery under different host conditions is timely. In this review, we will summarize recent developments in hippocampal transplants, especially the anatomical and/or functional integration of grafts within the host brain under specific host conditions, including a comparison of intact hippocampus with various types of hippocampal lesions or injury. Improvements in grafting techniques, methods for analysis of graft integration and graft function will be summarized, in addition to critical factors which enhance the survival and integration of grafted cells and alternative sources of donor cells currently being tested or considered for hippocampal transplantation. Viewed collectively, hippocampal grafting studies show that fetal hippocampal tissue/cells survive grafting, establish both afferent and efferent connections with the host brain, and are also capable of ameliorating certain learning and memory deficits in some models. However, the efficacy of intracerebral fetal hippocampal grafts varies considerably in different animal models, depending on several factors: the mode of donor tissue preparation, the method of grafting, the state of host hippocampus at the time of grafting, and the placement of grafts within the hippocampus. Functional improvement in many models appeared to be caused partially by re-establishment of damaged circuitry and partially by a trophic action of grafts. However, exact mechanisms of graft-mediated behavioral recovery remain to be clarified due to the lack of correlative analysis in the same animal between the degree of graft integration and behavioral recovery. Issues of mechanisms of action, degree of restoration of host circuitry and amelioration of host pathological conditions will need to be sorted out clearly prior to clinical use of fetal hippocampal transplants for susceptible neurological conditions. 相似文献
865.
The potential for stable crack growth preceding fracture in poly crystalline ceramics depends upon the functional relation between the local toughness and the crack length. The existence of a single crystal region of crack growth resistance is conducive to the occurrence of stable crack growth or crack arrest. If stable crack growth or crack arrest does occur, the strength will be independent of the initial crack size. 相似文献
866.
A.R. Rosenfield D.K. Shetty W.H. Duckworth 《Journal of the American Ceramic Society》1986,69(5):108-C
Safety factors are derived for converting bend data to tensile data for creep. It is assumed that the ceramic being stressed is subject to preferential damage in tension. The analysis shows that the safety factors can be relaxed considerably when compression data are available to augment the bend data. 相似文献
867.
Graham Price Manish Vachharajani 《Computer Architecture Letters》2006,5(2):18-18
Instruction-level traces are widely used for program and hardware analysis. However, program traces for just a few seconds of execution are enormous, up to several terabytes in size, uncompressed. Specialized compression can shrink traces to a few gigabytes, but trace analyzers typically stream the decompressed trace through the analysis engine. Thus, the complexity of analysis depends on the decompressed trace size (even though the decompressed trace is never stored to disk). This makes many global or interactive analyses infeasible. This paper presents a method to compress program traces using binary decision diagrams (BDDs). BDDs intrinsically support operations common to many desirable program analyses and these analyses operate directly on the BDD. Thus, they are often polynomial in the size of the compressed representation. The paper presents mechanisms to represent a variety of trace data using BDDs and shows that BDDs can store, in 1 GB of RAM, the entire data-dependence graph of traces with over 1 billion instructions. This allows rapid computation of global analyses such as heap-object liveness and dynamic slicing 相似文献
868.
Derek Messie Mina Jung Jae C. Oh Shweta Shetty Steven Nordstrom Michael Haney 《Artificial Intelligence Review》2006,25(4):299-312
This paper describes a comprehensive prototype of large-scale fault adaptive embedded software developed for the proposed
Fermilab BTeV high energy physics experiment. Lightweight self-optimizing agents embedded within Level 1 of the prototype
are responsible for proactive and reactive monitoring and mitigation based on specified layers of competence. The agents are
self-protecting, detecting cascading failures using a distributed approach. Adaptive, reconfigurable, and mobile objects for
reliablility are designed to be self-configuring to adapt automatically to dynamically changing environments. These objects
provide a self-healing layer with the ability to discover, diagnose, and react to discontinuities in real-time processing.
A generic modeling environment was developed to facilitate design and implementation of hardware resource specifications,
application data flow, and failure mitigation strategies. Level 1 of the planned BTeV trigger system alone will consist of
2500 DSPs, so the number of components and intractable fault scenarios involved make it impossible to design an ‘expert system’
that applies traditional centralized mitigative strategies based on rules capturing every possible system state. Instead,
a distributed reactive approach is implemented using the tools and methodologies developed by the Real-Time Embedded Systems
group. 相似文献
869.
Guan X Ramanathan S Garris JP Shetty RS Ensor M Bachas LG Daunert S 《Analytical chemistry》2000,72(11):2423-2427
A sensitive and selective sensing system for chlorocatechols (3-chlorocatechol and 4-chlorocatechol) was developed based on Pseudomonas putida bacteria harboring the plasmid pSMM50R-B'. In this plasmid, the regulatory protein of the clc operon, ClcR, controls the expression of the reporter enzyme beta-galactosidase. When bacteria containing components of the clc operon are grown in the presence of chlorocatechols, ClcR activates the clcA promoter, which is located upstream from the beta-galactosidase gene. Thus, the concentration of chlorocatechols can be related to the production of beta-galactosidase in the bacteria. The concentration of beta-galactosidase expressed in the bacteria was determined by measuring the chemiluminescence signal emitted with the use of a 1,2-dioxetane substrate. ClcR has a high specificity for chlorocatechols and provides the sensing system with high selectivity. This was demonstrated by evaluating several structurally related organic compounds as potential interfering agents. Both 3-chlorocatechol and 4-chlorocatechol can be detected with this sensing system at concentrations as low as 8 x 10(-10) and 2 x 10(-9) M, respectively, using a 2-h induction period. In the case of 3-chlorocatechol, a highly selective sensing system was developed that can detect this species at concentrations as low as 6 x 10(-8) M after a 5-min induction period; the presence of 4-chlorocatechol at concentrations as high as 2 x 10(-4) M did not interfere with this system. 相似文献
870.
Guang-Yong Lin Ramaswamy Lakshminarayanan Dinesh K. Shetty 《Journal of Materials Science》2007,42(10):3508-3519
A bearing-grade silicon nitride with fine microstructure and a turbine-grade silicon nitride with coarse microstructure were
studied with respect to the influence of their microstructures on (a) crack-growth-resistance behavior, (b) strength degradation
due to Vickers indentation, and (c) crack initiation in quasi-static indentation with WC spheres. The turbine grade exhibited
strong rising crack-growth resistance and less strength degradation due to Vickers indentation as compared to the bearing
grade. Partial-ring or C cracks initiated in Hertzian indentation and the critical loads exhibited linear (Auerbach) variation
with indenter radius above a critical value. For smaller radius, indentation plasticity preceded C-crack initiation. The bearing
grade exhibited higher critical loads for C-crack initiation, but showed greater extension toward a ring crack than the turbine
grade. These differences in crack initiation and growth were consistent with the differences in crack initiation and propagation
toughness of the two grades. A ball-on-ball impact analysis was used to predict the critical velocities for initiating C cracks
in the impact of silicon nitride surfaces with WC spheres. 相似文献