全文获取类型
收费全文 | 807篇 |
免费 | 21篇 |
国内免费 | 8篇 |
专业分类
电工技术 | 9篇 |
化学工业 | 193篇 |
金属工艺 | 34篇 |
机械仪表 | 14篇 |
建筑科学 | 35篇 |
能源动力 | 32篇 |
轻工业 | 84篇 |
水利工程 | 10篇 |
石油天然气 | 1篇 |
无线电 | 46篇 |
一般工业技术 | 123篇 |
冶金工业 | 151篇 |
原子能技术 | 12篇 |
自动化技术 | 92篇 |
出版年
2023年 | 5篇 |
2022年 | 29篇 |
2021年 | 40篇 |
2020年 | 18篇 |
2019年 | 16篇 |
2018年 | 16篇 |
2017年 | 22篇 |
2016年 | 18篇 |
2015年 | 19篇 |
2014年 | 18篇 |
2013年 | 47篇 |
2012年 | 32篇 |
2011年 | 50篇 |
2010年 | 28篇 |
2009年 | 38篇 |
2008年 | 38篇 |
2007年 | 21篇 |
2006年 | 34篇 |
2005年 | 17篇 |
2004年 | 11篇 |
2003年 | 22篇 |
2002年 | 18篇 |
2001年 | 11篇 |
2000年 | 7篇 |
1999年 | 18篇 |
1998年 | 41篇 |
1997年 | 25篇 |
1996年 | 22篇 |
1995年 | 25篇 |
1994年 | 12篇 |
1993年 | 10篇 |
1992年 | 4篇 |
1991年 | 4篇 |
1990年 | 5篇 |
1989年 | 8篇 |
1988年 | 10篇 |
1987年 | 7篇 |
1986年 | 13篇 |
1985年 | 3篇 |
1984年 | 5篇 |
1983年 | 4篇 |
1981年 | 7篇 |
1980年 | 3篇 |
1979年 | 6篇 |
1978年 | 9篇 |
1977年 | 6篇 |
1976年 | 4篇 |
1975年 | 3篇 |
1972年 | 2篇 |
1964年 | 1篇 |
排序方式: 共有836条查询结果,搜索用时 0 毫秒
11.
The corrosion of M–Nb alloys based on iron, cobalt, and nickel and containing 15 and 30 wt% Nb has been studied at 600–800°C under low oxygen pressures (10–24 atm at 600°C and 10–20 atm at 700–800°C). Except for the Co–Nb and Ni–Nb alloys corroded at 800°C, which formed external scales of niobium oxides, corrosion under low O2 pressures produced an internal oxidation of niobium. This attack was much faster than expected on the basis of the classical theory. Furthermore, the distribution of the internal oxide in the alloys containing two metal phases was very close to that of the Nb-rich phase in the original alloys. These kinetic, microstructural, and thermodynamic aspects are examined by taking into account the effects of the limited solubility of niobium in the various base metals and of the two-phase nature of the alloys. 相似文献
12.
Cabral RM Ferraz MS Rizzo M Sousa FD Rodrigues NM Ibiapina PB Ambrósio CE De Carvalho MA 《Microscopy research and technique》2012,75(5):566-570
The aim of this study is to show histological and immunofluorescence analysis of renal parenchyma of agoutis affected by gentamicin‐induced renal disease after the infusion of bone marrow mononuclear cells (BMMC) stained with Hoechst®. Nine agouti's males were divided into three groups: Test group (TG): renal disease by gentamicin induced (n = 3), cell therapy group (CTG): renal disease by gentamicin induced and BMMC infusion (n = 3), and control group (CG): nonrenal disease and BMMC infusion (n = 3). TG and CTG were submitted to the protocol of renal disease induction using weekly application of gentamicin sulfate for 4 months. CG and CTG received a 1 × 108 BMMC stained with Hoechst and were euthanized for kidney examination 21 days after BMMC injection and samples were collected for histology and immunofluorescence analysis. Histological analysis demonstrated typical interstitial lesions in kidney similarly to human disease, as tubular necrosis, glomerular destruction, atrophy tubular, fibrotic areas, and collagen deposition. We conclude that histological analysis suggest a positive application of agouti's as a model for a gentamicin inducing of kidney disease, beyond the immunofluorescence analysis suggest a significant migration of BMMC to sites of renal injury in CTG. Microsc. Res. Tech., 2012. © 2011 Wiley Periodicals, Inc. 相似文献
13.
A software environment, called EDEN, that prototypes a recent approach to model-based diagnosis of discrete-event systems, is presented. The environment integrates a specification language, called SMILE, a model base, and a diagnostic engine. SMILE enables the user to create libraries of models and systems, which are permanently stored in the model base, wherein both final and intermediate results of the diagnostic sessions are hosted as well. Given the observation of a physical system gathered during its reaction to an external event, the diagnostic engine performs the a posteriori reconstruction of all the possible evolutions of the system over time and, then, draws candidate diagnoses out of them. The diagnostic method is described using a simplified example within the domain of power transmission networks. Strong points of the method include compositional modeling, support for model update, ability to focus on any sub-system, amenability to parallel execution, management of multiple faults, and broad notions of system and observation. 相似文献
14.
The virtual classroom provides an efficient and scalable tool for conducting attention testing. The University of Southern California integrated media systems center and digital media works have partnered to develop virtual reality technology applications for the study, assessment, and rehabilitation of cognitive and functional processes. This work primarily focuses on the development of systems that address the special needs of clinical populations with central nervous system dysfunctions such as brain injury, learning disabilities, or neurological disorders. 相似文献
15.
Gianfranco Bianco 《机械工人(冷加工)》2006,(11):45-46
一直以来,齿轮热处理后的精加工一般采用磨削或珩磨这两项工艺,但剃齿加工工艺仍有现实意义。首先,剃齿总费用仅是磨削总费用的一部分;其次,剃齿加工所用循环时间要短得多,这就意味着剃齿加工投入的资金和必需的机床要少很多。另外,还要考虑到齿轮加工不可能都采用磨削加工,有些精度不高的齿轮不需要磨削加工,比如带台肩的齿轮,汽车的倒挡齿轮与一、二挡齿轮,所有农业机械的齿轮以及低速的传动齿轮。 相似文献
16.
The computation of strongly connected components (SCCs) in discrete-state models is a critical step in formal verification
of LTL and fair CTL properties, but the potentially huge number of reachable states and SCCs constitutes a formidable challenge.
We consider the problem of computing the set of states in SCCs or terminal SCCs in an asynchronous system. We employ the idea
of saturation, which has shown clear advantages in symbolic state-space exploration (Ciardo et al. in Softw Tools Technol Transf 8(1):4–25,
2006; Zhao and Ciardo in Proceedings of 7th international symposium on automated technology for verification and analysis, pp
368–381, 2009), to improve two previously proposed approaches. We use saturation to speed up state exploration when computing each SCC
in the Xie-Beerel algorithm, and we compute the transitive closure of the transition relation using a novel algorithm based on saturation. Furthermore, we show that the techniques we developed
are also applicable to the computation of fair cycles. Experimental results indicate that the improved algorithms using saturation achieve a substantial speedup over previous
BFS algorithms. In particular, with the new transitive closure computation algorithm, up to 10150 SCCs can be explored within a few seconds. 相似文献
17.
Bibiana C. Mota Nathan Ashburner Laura Abelleira-Hervas Liyueyue Liu Robertas Aleksynas Lucio Claudio Rovati Gianfranco Caselli Magdalena Sastre 《International journal of molecular sciences》2022,23(13)
Recent evidence suggests that I2-imidazoline ligands have neuroprotective properties in animal models of neurodegeneration, such as Alzheimer’s disease (AD). We recently demonstrated that the I2-ligand BU224 reversed memory impairments in AD transgenic mice and this effect was not because of reductions in amyloid-β (Aβ) deposition. In this study, our aim was to determine the therapeutic potential of the powerful analgesic I2-imidazoline ligand CR4056 in the 5xFAD model of AD, since this ligand has been proven to be safely tolerated in humans. Sub-chronic oral administration of CR4056 (30 mg/kg for 10 days) led to an improvement in recognition memory in 6-month-old 5xFAD mice, but not in wild-type littermates, without affecting Aβ levels or deposition. Our results also revealed a change in the profile of microglia by CR4056, resulting in a suppression of pro-inflammatory activated microglia, but increased the density of astrocytes and the expression of ApoE, which is mainly produced by these glial cells. In addition, CR4056 restored fibrinogen extravasation, affecting the distribution of markers of astrocytic end feet in blood vessels. Therefore, these results suggest that CR4056 protects against Aβ-mediated neuroinflammation and vascular damage, and offers therapeutic potential at any stage of AD. 相似文献
18.
Paola Riolo Roxana L. Minuz Gianfranco Anfora Marco V. Rossi Stacconi Silvia Carlin Nunzio Isidoro Roberto Romani 《Journal of chemical ecology》2012,38(8):1017-1030
The Palearctic planthopper Hyalesthes obsoletus is the natural vector of the grapevine yellow disease Bois noir. Grapevine is an occasional host plant of this polyphagous planthopper. To deepen our knowledge of the role of plant volatile organic compounds for H. obsoletus host plant searching, we carried out behavioral, morphological, and electrophysiological studies. We tested the attraction of H. obsoletus to nettle, field bindweed, hedge bindweed, chaste tree, and grapevine by using a Y-shaped olfactometer. The results showed a significant attraction of male H. obsoletus to chaste tree, and of the females to nettle. Male H. obsoletus were repelled by odor from hedge bindweed. Ultrastructural studies of the antennae showed at least two types of olfactory sensilla at the antennal pedicel: plaque organs and trichoid sensilla. Volatile organic compounds from nettle and chaste tree were collected, and the extracts were analyzed by coupling gas-chromatography to both mass-spectrometry and electroantennography. The volatile organic compounds that elicited electrophysiological responses in male and female antennae were identified. These findings are discussed with respect to behavior of H. obsoletus males and females in the field. 相似文献
19.
Nancy A. Skopp Derek J. Smolenski Melinda J. Metzger-Abamukong Albert A. Rizzo Greg M. Reger 《International journal of human-computer interaction》2014,30(1):24-31
This pilot study assessed the utility and acceptability of the VirtuSphere, a cutting edge navigation platform designed to enhance presence in virtual environments. The VirtuSphere includes a 12-ft hollow sphere within which the user stands, and it rolls within a wheeled platform, in any direction, according to the user's steps. The pilot was a within-subject crossover design comparing the VirtuSphere to standard game controller navigation. The comparison was based on locomotion in Virtual Iraq, a virtual world resembling Iraqi war zones. Participants were 10 active duty soldiers not suffering from posttraumatic stress disorder. Results indicated that there were negligible differences in sense of presence, simulator sickness, and satisfaction across the two navigation systems. Although the VirtuSphere may provide entertainment value, these results do not provide initial support for the use of the VirtuSphere to improve constructs thought to be important to behavioral health applications of virtual reality. Potential improvements to the design of the VirtuSphere are discussed. 相似文献
20.