全文获取类型
收费全文 | 772篇 |
免费 | 12篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 17篇 |
综合类 | 1篇 |
化学工业 | 194篇 |
金属工艺 | 22篇 |
机械仪表 | 14篇 |
建筑科学 | 29篇 |
能源动力 | 25篇 |
轻工业 | 48篇 |
水利工程 | 3篇 |
无线电 | 103篇 |
一般工业技术 | 150篇 |
冶金工业 | 67篇 |
原子能技术 | 3篇 |
自动化技术 | 110篇 |
出版年
2022年 | 14篇 |
2021年 | 25篇 |
2020年 | 19篇 |
2019年 | 16篇 |
2018年 | 23篇 |
2017年 | 19篇 |
2016年 | 13篇 |
2015年 | 13篇 |
2014年 | 15篇 |
2013年 | 50篇 |
2012年 | 19篇 |
2011年 | 27篇 |
2010年 | 20篇 |
2009年 | 27篇 |
2008年 | 37篇 |
2007年 | 23篇 |
2006年 | 21篇 |
2005年 | 22篇 |
2004年 | 20篇 |
2003年 | 14篇 |
2002年 | 16篇 |
1999年 | 7篇 |
1998年 | 21篇 |
1997年 | 21篇 |
1996年 | 12篇 |
1995年 | 12篇 |
1994年 | 9篇 |
1993年 | 8篇 |
1992年 | 8篇 |
1991年 | 11篇 |
1990年 | 13篇 |
1989年 | 8篇 |
1988年 | 16篇 |
1987年 | 8篇 |
1986年 | 7篇 |
1985年 | 6篇 |
1984年 | 15篇 |
1983年 | 13篇 |
1982年 | 11篇 |
1981年 | 7篇 |
1980年 | 10篇 |
1979年 | 12篇 |
1978年 | 8篇 |
1977年 | 6篇 |
1976年 | 19篇 |
1975年 | 12篇 |
1974年 | 8篇 |
1973年 | 5篇 |
1971年 | 8篇 |
1970年 | 5篇 |
排序方式: 共有786条查询结果,搜索用时 15 毫秒
131.
132.
This paper discusses the significance of segmental and prosodic knowledge sources for developing a text-to-speech system for
Indian languages. Acoustic parameters such as linear prediction coefficients, formants, pitch and gain are prestored for the
basic speech sound units corresponding to the orthographic characters of Hindi. The parameters are concatenated based on the
input text. These parameters are modified by stored knowledge sources corresponding to coarticulation, duration and intonation.
The coarticulation rules specify the pattern of joining the basic units. The duration rules modify the inherent duration of
the basic units based on the linguistic context in which the units occur. The intonation rules specify the overall pitch contour
for the utterance (declination or rising contour), fall-rise patterns, resetting phenomena and inherent fundamental frequency
of vowels. Appropriate pauses between syntactic units are specified to enhance intelligibility and naturalness. 相似文献
133.
We generalize earlier results in VLSI layout theory by considering variable aspect ratio embeddings for VLSI graphs. By aspect ratio we mean the ratio of the length of the longer side to the length of the shorter side of the bounding rectangle of the embedding. Our results are based on separators and bifurcators. We obtain embeddings with existentially optimal area and any desired aspect ratio. Additionally, we can obtain either bounded capacitive delay or existentially optimal minimax edge length in the embeddings; both of these features reduce delays in the circuit. A special feature of our results on minimax edge length is that they unify earlier separator- and bifurcator-based results for square embeddings, and also provide a simplified lower bound proof. 相似文献
134.
A Multi-radio 802.11 Mesh Network Architecture 总被引:2,自引:0,他引:2
Krishna Ramachandran Irfan Sheriff Elizabeth M. Belding Kevin Almeroth 《Mobile Networks and Applications》2008,13(1-2):132-146
The focus of this paper is to offer a practical multi-radio mesh network architecture that can realize the benefits of multiple radios. Our architecture provides solutions to challenges in three key areas. The first is the construction of a split wireless router that enables modular wireless mesh routers to be constructed from commodity hardware. The second is the design of a centralized channel assignment algorithm that considers the inter-dependence between channel assignment and routing in order to create high-throughput channel-diversified routes. Third is the design and implementation of several communication protocols that are necessary to make our architecture operational. Our system is comprehensively evaluated on a 20-node multi-radio wireless testbed. Results demonstrate that our architecture makes feasible the deployment of large-scale high-capacity multi-radio mesh networks built entirely with commodity hardware. Our implementation is available to the community for research and development purposes. 相似文献
135.
Gonadotropin-inhibitory hormone (GnIH) receptor gene is expressed in the chicken ovary: potential role of GnIH in follicular maturation 总被引:1,自引:0,他引:1
Maddineni SR Ocón-Grove OM Krzysik-Walker SM Hendricks GL Ramachandran R 《Reproduction (Cambridge, England)》2008,135(2):267-274
Gonadotropin-inhibitory hormone (GnIH), an RFamide peptide, has been found to inhibit pituitary LH secretion in avian and mammalian species. The gene encoding a putative receptor for GnIH (GnIHR) was recently identified in the chicken and Japanese quail brain and pituitary gland. GnIHR appears to be a seven-transmembrane protein belonging to a family of G-protein-coupled receptors. In the present study, we have characterized the expression of GnIHR mRNA in the chicken ovary and demonstrate that GnIHR may exert an inhibitory effect on ovarian follicular development. By RT-PCR, we detected GnIHR mRNA in the chicken testis and in the ovary, specifically both thecal and granulosa cell layers. Real-time quantitative PCR analysis revealed greater GnIHR mRNA quantity in theca cells of prehierarchial follicles compared with that of preovulatory follicles. GnIHR mRNA quantity was significantly decreased in sexually mature chicken ovaries versus ovaries of sexually immature chickens. Estradiol (E(2)) and/or progesterone (P(4)) treatment of sexually immature chickens significantly decreased ovarian GnIHR mRNA abundance. Treatment of prehierarchial follicular granulosa cells in vitro with chicken GnIH peptide significantly decreased basal but not FSH-stimulated cellular viability. Collectively, our results indicate that the ovarian GnIHR is likely to be involved in ovarian follicular development. A decrease in ovarian GnIHR mRNA abundance due to sexual maturation or by E(2) and/or P(4) treatment would implicate an inhibitory role for GnIHR in ovarian follicular development. Furthermore, GnIH may affect follicular maturation by decreasing the viability of prehierarchial follicular granulosa cells through binding to GnIHR. 相似文献
136.
Khan Imran Tango Charles Nkufi Chelliah Ramachandran Oh Deog-Hwan 《Food science and biotechnology》2019,28(4):1257-1264
Food Science and Biotechnology - Edible antimicrobial coating produced from chitosan (CS) and its derivative was applied to improve the shelf life of fresh strawberries at 10 °C.... 相似文献
137.
Kaya Demir Vijay Sukumaran Yoichiro Sato Abderrahim El Amrani Koushik Ramachandran Raghuram Pucha P. Markondeya Raj Venkatesh Sundaram Rao Tummala 《Journal of Materials Science: Materials in Electronics》2018,29(15):12669-12680
Glass is an ideal substrate material to enable 2.5D and 3D packaging of ICs at low cost and high performance. However, it is a brittle material and is prone to failures during fabrication and operation. Large coefficient of thermal expansion (CTE) mismatch between copper and glass leads to thermomechanical stresses that can lead to glass cracking and delamination from glass interfaces. This paper focuses on modeling and reliability characterization of copper-plated through-package-vias (TPV) in glass packages. Thermomechanical simulations were carried out to obtain design guidelines for reliable TPVs in glass. Test-vehicles with different glass thicknesses and copper TPV fabrication conditions were fabricated for thermal cycling tests, resistance monitoring and failure analysis. The reliability characterization results showed good thermomechanical reliability of TPVs in ultra-thin glass panels. 相似文献
138.
Strength of Materials - In this work, the effect of axial force on the tensile strength, microhardness, joint interface microstructure and fracture surface morphology of friction stir welded (FSW)... 相似文献
139.
Chidambaram Siva Ramachandran Krithikadevi Gaidi Mounir Daoudi Kais Natarajamoorthy Mathan 《Journal of Materials Science: Materials in Electronics》2022,33(12):9134-9143
Journal of Materials Science: Materials in Electronics - Iron tungstate (FeWO4) nanoparticles were prepared by simple solution combustion technique. The preparation method discloses the first... 相似文献
140.
Kai Lin Zhao Ma Jin Li Menghuan Tang Aaron Lindstrom Mythili Ramachandran Shaoming Zhu Tzu-yin Lin Lanwei Zhang Yuanpei Li 《Advanced functional materials》2021,31(10):2008460
Photodynamic therapy (PDT) has emerged as an attractive alternative in cancer therapy, but its therapeutic effects are limited by the nonselective subcellular localization and poor intratumoral retention of small-molecule photosensitizes. Here a fiber-forming nanophotosensitizer (PQC NF) that is composed of mitochondria targeting small molecules of amphiphilicity is reported. Harnessing the specific mitochondria targeting, the light-activated PQC NFs produce approximately 110-fold higher amount of reactive oxygen species in cells than free photosensitizers and can dramatically induce mitochondrial disruption to trigger intense apoptosis, showing 20–50 times better in vitro anticancer potency than traditional photosensitizers. As fiber-shaped nanomaterials, PQC NFs also demonstrated a long-term retention in tumor sites, solving the challenge of rapid clearance of small-molecule photosensitizers from tumors. With these advantages, PQC NFs achieve a 100% complete cure rate in both subcutaneous and orthotopic oral cancer models with the administration of only a single dose. This type of single small molecule-assembled mitochondria targeting nanofibers offers an advantageous strategy to improve the in vivo therapeutic effects of conventional PDT. 相似文献