全文获取类型
收费全文 | 3349篇 |
免费 | 249篇 |
国内免费 | 13篇 |
专业分类
电工技术 | 21篇 |
综合类 | 4篇 |
化学工业 | 824篇 |
金属工艺 | 135篇 |
机械仪表 | 227篇 |
建筑科学 | 53篇 |
能源动力 | 123篇 |
轻工业 | 378篇 |
水利工程 | 27篇 |
石油天然气 | 2篇 |
无线电 | 564篇 |
一般工业技术 | 674篇 |
冶金工业 | 176篇 |
原子能技术 | 38篇 |
自动化技术 | 365篇 |
出版年
2024年 | 3篇 |
2023年 | 57篇 |
2022年 | 72篇 |
2021年 | 119篇 |
2020年 | 95篇 |
2019年 | 107篇 |
2018年 | 111篇 |
2017年 | 131篇 |
2016年 | 175篇 |
2015年 | 118篇 |
2014年 | 193篇 |
2013年 | 244篇 |
2012年 | 251篇 |
2011年 | 301篇 |
2010年 | 223篇 |
2009年 | 179篇 |
2008年 | 192篇 |
2007年 | 154篇 |
2006年 | 125篇 |
2005年 | 106篇 |
2004年 | 74篇 |
2003年 | 74篇 |
2002年 | 79篇 |
2001年 | 76篇 |
2000年 | 47篇 |
1999年 | 50篇 |
1998年 | 83篇 |
1997年 | 35篇 |
1996年 | 32篇 |
1995年 | 18篇 |
1994年 | 12篇 |
1993年 | 10篇 |
1992年 | 4篇 |
1991年 | 9篇 |
1990年 | 11篇 |
1989年 | 9篇 |
1988年 | 7篇 |
1987年 | 6篇 |
1986年 | 4篇 |
1985年 | 4篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1975年 | 2篇 |
1966年 | 1篇 |
排序方式: 共有3611条查询结果,搜索用时 0 毫秒
991.
Structural Color Palettes of Core–Shell Photonic Ink Capsules Containing Cholesteric Liquid Crystals 下载免费PDF全文
Sang Seok Lee Hyeon Jin Seo Yun Ho Kim Shin‐Hyun Kim 《Advanced materials (Deerfield Beach, Fla.)》2017,29(23)
Photonic microcapsules with onion‐like topology are microfluidically designed to have cholesteric liquid crystals with opposite handedness in their core and shell. The microcapsules exhibit structural colors caused by dual photonic bandgaps, resulting in a rich variety of color on the optical palette. Moreover, the microcapsules can switch the colors from either core or shell depending on the selection of light‐handedness. 相似文献
992.
Exceptionally High Ionic Conductivity in Na3P0.62As0.38S4 with Improved Moisture Stability for Solid‐State Sodium‐Ion Batteries 下载免费PDF全文
993.
H. K. Seo Farheen S. A. Ansari Nazish Parveen Shabeena Qadir H. Fouad H. S. Shin Moo Hwan Cho S. G. Ansari Z. A. Ansari 《Journal of Materials Science: Materials in Electronics》2017,28(4):3210-3216
Extensive research have been made in improving the dye sensitized solar cells (DSSC) performance by designing, tailoring and enhancing the photoconversion properties of the matrix. The approaches used are material synthesis, dye permutation combinations, use of natural extracts or using several sensitizers. The polymers are also being explored in this regards in their pristine or composite forms. Therefore, in this study an attempt is made to synthesize a mesoporous polyaniline–titanium dioxide (PANI–TiO2) nanocomposites with one pot synthesis approach at different concentrations of PANI (0.3–0.7 ml). Titanium isopropoxide was used as precursor for TiO2 with aniline and the material was synthesized at ice bath temperature. Morphological observations showed that the composite is a mesoporous material with tubular structure where TiO2 particles are seen entrapped in the polymer matrix and found that intercalation can be tailored with PANI concentration. Structural, functional and optical characterization indicate anatase phase of TiO2, with several functional bands that can help in dye interaction and broad absorption bands within visible region. The photocurrent-voltage response was measured with simulated light and source-meter. It is interesting to note that increasing PANI concentration enhances the mesoporous structure and hence increases the dye loading capacity and photoconductivity of the material. The efficiency increased by about 22 % with addition of 0.5 ml of PANI from 0.3 ml. The proposed study has indicated that such material have the potential to be used for DSSC fabrication with which the device performance can further be increased to a better levels. 相似文献
994.
Jinyoung Seo Sungi Kim Ha H. Park Jwa‐Min Nam 《Small (Weinheim an der Bergstrasse, Germany)》2019,15(26)
Biocomputation is the algorithmic manipulation of biomolecules. Nanostructures, most notably DNA nanostructures and nanoparticles, become active substrates for biocomputation when modified with stimuli‐responsive, programmable biomolecular ligands. This approach—biocomputing with nanostructures (“nano‐bio computing”)—allows autonomous control of matter and information at the nanoscale; their dynamic assemblies and beneficial properties can be directed without human intervention. Recently, lipid bilayers interfaced with nanostructures have emerged as a new biocomputing platform. This new nano‐bio interface, which exploits lipid bilayers as a chemical circuit board for information processing, offers a unique reaction space for realizing nanostructure‐based computation at a previously unexplored dimension. In this Concept, recent advances in nano‐bio computing are briefly reviewed and the newly emerging concept of biocomputing with nanostructures on lipid bilayers is introduced. 相似文献
995.
Jeongyeon Seo Juan Kim Sunghoon Joo Ji Yu Choi Kyungtae Kang Woo Kyung Cho Insung S. Choi 《Small (Weinheim an der Bergstrasse, Germany)》2018,14(33)
Axon collateral branches, as a key structural motif of neurons, allow neurons to integrate information from highly interconnected, divergent networks by establishing terminal boutons. Although physical cues are generally known to have a comprehensive range of effects on neuronal development, their involvement in axonal branching remains elusive. Herein, it is demonstrated that the nanopillar arrays significantly increase the number of axon collateral branches and also promote their growth. Immunostaining and biochemical analyses indicate that the physical interactions between the nanopillars and the neurons give rise to lateral filopodia at the axon shaft via cytoskeletal changes, leading to the formation of axonal branches. This report, demonstrates that nanotopography regulates axonal branching, and provides a guideline for the design of sophisticated neuron‐based devices and scaffolds for neuro‐engineering. 相似文献
996.
Nucleic acid vaccines have attracted enormous attention for resolving the limitations of conventional vaccines using live attenuated viruses. Because nucleic acid vaccines can be produced rapidly in response to the emergence of new virus strains, they are more appropriate for the control of urgent epidemic and pandemic issues. In particular, messenger RNA (mRNA) vaccines have evolved as a new type of nucleic acid vaccines in accordance with their superior protein expression and a lack of mutagenesis as compared with DNA vaccines. Using mRNA vaccines, large amounts of target proteins can be expressed in immune cells for efficient immunization. For instance, antigen-specific vaccination is a feasible option involving the expression of specific antigens in antigen-presenting cells. Immunological reactions are modulated by expressing several proteins associated with stimulation or maturation of immune cells. In addition, mRNA vaccines can stimulate innate immunity through specific recognition by pattern recognition receptors. On the basis of these remarkable properties, mRNA vaccines have been used for prophylactic and therapeutic applications. This review highlights the role of mRNA vaccines as prophylactic vaccines for prevention of future infections and as therapeutic vaccines for cancer immunotherapy. In addition to the conventional type of mRNA vaccines, RNA replicons (self-amplifying mRNA vaccines) will be described. 相似文献
997.
Jung Seo Park Jong Gye Shin Chung Min Hyun Young Chil Doh Kwang Hee Ko 《Computer aided design》2009,41(12):907-917
Various problems associated with localization during curved plate fabrication are discussed. Localization is a necessary step for automation of curved plate fabrication that aligns a designed shape with a fabricated one as closely as possible for comparison of their shapes. On top of this localization, various conditions are introduced to reflect requirements occurring during fabrication such as minimum cutting length, maintenance of cutting length, localization for non-penetration and data types for localization. Each condition is formulated as a constraint which is provided as input to the optimization problem for localization. Algorithms for localization with each constraint based on iteration are proposed. Examples are used to demonstrate the performance of the algorithms. 相似文献
998.
Hyun-Jung Kim Yu-Deok Seo Sung-Kie Youn 《Computer Methods in Applied Mechanics and Engineering》2010,199(45-48):2796-2812
Trimming technique is a powerful and efficacious way of endowing an arbitrary complex topology to CAD files created by using NURBS. In the present work, it is shown that any complex multiply-connected NURBS domain can be described by using trimming curves only. Isogeometric analysis for linear elasticity problems of complex topology described in this way is presented. For fully communicative interaction between CAD and CAE, a specific searching algorithm and an integration scheme of trimmed elements are introduced to utilize the IGES files exported from CAD system for Isogeometric analysis. Schemes for imposing essential and traction boundary conditions on trimming curves are presented. It has been demonstrated that with the presented schemes trimmed cases in any complicated situations can be successfully treated. With the examples of complex topology that could be described by employing trimming curves only, effectiveness and robustness of present method are demonstrated. 相似文献
999.
The development of a sliding joint for very flexible multibody dynamics using absolute nodal coordinate formulation 总被引:1,自引:0,他引:1
Soo-Ho Lee Tae-Won Park Jong-Hwi Seo Ji-Won Yoon Kab-Jin Jun 《Multibody System Dynamics》2008,20(3):223-237
In this paper, a formulation for a spatial sliding joint is derived using absolute nodal coordinates and non-generalized coordinate
and it allows a general multibody move along a very flexible cable. The large deformable motion of a spatial cable is presented
using absolute nodal coordinate formulation, which is based on the finite element procedures and the general continuum mechanics
theory to represent the elastic forces. And the nongeneralized coordinate, which is related to neither the inertia forces
nor the external forces, is used to describe an arbitrary position along the centerline of a very flexible cable. Hereby,
the non-generalized coordinate represents the arc-length parameter. The constraint equations for the sliding joint are expressed
in terms of generalized coordinate and nongeneralized coordinate. In the constraint equations for the sliding joint, one constraint
equation can be systematically eliminated. There are two independent Lagrange multipliers in the final system equations of
motion associated with the sliding joint. The development of this sliding joint is important to analyze many mechanical systems
such as pulley systems and pantograph-catenary systems for high speed-trains. 相似文献
1000.
In optimization problems, the contribution of a variable to fitness often depends on the states of other variables. This phenomenon is referred to as epistasis or linkage. In this paper, we show that a new theory of epistasis can be established on the basis of Shannon's information theory. From this, we derive a new epistasis measure called entropic epistasis and some theoretical results. We also provide experimental results verifying the measure and showing how it can be used for designing efficient evolutionary algorithms. 相似文献