全文获取类型
收费全文 | 697篇 |
免费 | 48篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 87篇 |
综合类 | 8篇 |
化学工业 | 196篇 |
金属工艺 | 18篇 |
机械仪表 | 21篇 |
建筑科学 | 18篇 |
矿业工程 | 6篇 |
能源动力 | 31篇 |
轻工业 | 48篇 |
水利工程 | 2篇 |
石油天然气 | 20篇 |
武器工业 | 6篇 |
无线电 | 73篇 |
一般工业技术 | 135篇 |
冶金工业 | 21篇 |
原子能技术 | 13篇 |
自动化技术 | 47篇 |
出版年
2024年 | 5篇 |
2023年 | 4篇 |
2022年 | 17篇 |
2021年 | 20篇 |
2020年 | 9篇 |
2019年 | 16篇 |
2018年 | 13篇 |
2017年 | 10篇 |
2016年 | 18篇 |
2015年 | 25篇 |
2014年 | 31篇 |
2013年 | 64篇 |
2012年 | 32篇 |
2011年 | 48篇 |
2010年 | 38篇 |
2009年 | 45篇 |
2008年 | 37篇 |
2007年 | 22篇 |
2006年 | 32篇 |
2005年 | 13篇 |
2004年 | 18篇 |
2003年 | 22篇 |
2002年 | 24篇 |
2001年 | 13篇 |
2000年 | 12篇 |
1999年 | 7篇 |
1998年 | 14篇 |
1997年 | 9篇 |
1996年 | 16篇 |
1995年 | 6篇 |
1994年 | 17篇 |
1993年 | 7篇 |
1992年 | 5篇 |
1991年 | 4篇 |
1990年 | 9篇 |
1989年 | 2篇 |
1988年 | 6篇 |
1987年 | 4篇 |
1986年 | 7篇 |
1985年 | 5篇 |
1984年 | 6篇 |
1983年 | 8篇 |
1982年 | 6篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1979年 | 3篇 |
1978年 | 4篇 |
1977年 | 3篇 |
1976年 | 2篇 |
1969年 | 2篇 |
排序方式: 共有750条查询结果,搜索用时 15 毫秒
1.
2.
3.
Beneficial effects of dietary phytic acid (myo-inositol hexaphosphate; IP6) have often been explained by its strong iron ion-chelating ability, which possibly suppresses iron ion-induced oxidative
damage in the gastrointestinal tract. Because phytic acid is hydrolyzed during digestion, this work aimed to know whether
its hydrolysis products (IP2′ IP3′, IP4′ and IP5) could still prevent iron ion-induced lipid peroxidation. Studies using liposomal membranes demonstrated that hydrolysis
products containing three or more phosphate groups are able to inhibit iron ion-induced lipid peroxidation although their
effectiveness decreased with dephosphorylation. Similarly, they also prevented iron ion-induced decomposition of phosphatidylcholine
hydroperoxide. These results demonstrate that intermediate products of phytic acid hydrolysis still possess iron ion-chelating
ability, and thus they can probably prevent iron ion-induced lipid peroxidation in biological systems. 相似文献
4.
The crystalline complex between poly(γ-methyl l-glutamate) (PMLG) and dimethyl phthalate (DMP) has been formed in films cast from a solution in dichloroethane. It has the stoichiometry of 1 mol of DMP to three or four residues of PMLG and shows two definite characteristics in X-ray diffraction patterns; one is the large hexagonal unit cell with the edge of around 28 Å and another the ‘extra’ 5.07 Å meridional reflection which can not be interpreted by a PMLG α-helical conformation. The structural examination for the films with various DMP contents is carried out by X-ray, viscoelastic, and d.s.c. measurements and the following structure is proposed for the crystalline complex. Four PMLG are associated to form a group which is hexagonally packed and DMP molecules, located in the gaps between groups, form a specific favourable helical structure along PMLG chains in which the van der Waals stacking of benzene rings of DMP is significant. 相似文献
5.
Response to walnut olfactory and visual cues by the parasitic wasp Diachasmimorpha juglandis 总被引:2,自引:0,他引:2
Diachasmimorpha juglandis is a specialist parasitoid attacking fly larvae in the genus Rhagoletis that feed exclusively on walnut fruit husks. In a free-foraging assay comparing response to uninfested, infested, and mechanically damaged fruits, we first determined that D. juglandis use host feeding damage on the fruit as a cue for host presence. In another free-foraging assay that used artificial walnut models and wind tunnel experiments, D. juglandis distinguished infested from uninfested fruits by using either olfactory or visual cues separately. However, the response rate of wasps in the wind tunnel was raised considerably when visual cues were also available. We analyzed the volatile compounds emitted by cohorts of uninfested, mechanically damaged, and infested fruits 1, 3, 5, 8, and 10 days after oviposition by flies into the infested fruits. Total volatile emissions did not differ significantly among treatments, but quantitative changes in volatiles distinguished infested fruits from uninfested and damaged fruits. The fact that parasitoids did not distinguish between infested and damaged fruits in assays where damage was visible indicates that they rely on visual cues when those are available. 相似文献
6.
基于Visual C#语言实现了有限状态自动机.该自动机具有小巧轻便、简单易用的优点,可应用于程序复杂界面的操作与控制. 相似文献
7.
Masahiro Nakagawa Tadashi Kondo Tsuyosi Kudo Shoichiro Takao Junji Ueno 《Artificial Life and Robotics》2009,14(2):118-122
In this study, we propose a revised radial basis function (RBF) neural network algorithm and apply this algorithm to computer-aided diagnosis (CAD) of the liver. First, the revised RBF neural network algorithm is applied to recognition of the liver regions, and the recognition results are compared with those obtained using the conventional RBF neural network and the conventional multilayered neural network trained using the back-propagation algorithm. It is shown that the revised RBF neural network is accurate, and is a useful method because the parameters are automatically determined. Then, the revised RBF neural network is applied to CAD of the liver cancer called hepatocellular carcinoma (HCC). 相似文献
8.
姜俊吉 《北京电子科技学院学报》2013,21(3):63-68
近年来,互联网行业的竞争越演越烈。综合门户网站的专业频道如何能在激烈的角逐中脱颖而出、做大做强?本文着重探讨综合门户网站专业频道的发展方向——垂直化。用户的需求和运营的需求达到双赢,才是互联网发展的最终出路。行业垂直门户网站的发展为我们提供了借鉴,个人认为,综合网站专业频道发展的终极目标就是要将各个频道做成一个个小型行业垂直门户,才能最终带动起整个综合网站的发展。 相似文献
9.
Masaji Tanaka Author Vitae Laurence Anthony Author Vitae Toshiaki Kaneeda Author Vitae Junji Hirooka Author Vitae 《Computer aided design》2004,36(8):723-734
Although solid models play a central role in modern CAD systems, 2D CAD systems are still commonly used for designing products without complex curved faces. Therefore, an important task is to convert 2D drawings to solid models, and this is usually carried out manually even in present CAD systems. Many methods have been proposed to automatically convert orthographic part drawings of solid objects to solid models. Unfortunately, products are usually drawn as 2D assembly drawings, and therefore, these methods cannot be applied. A further problem is the difficult and time-consuming task of decomposing 2D assembly drawings into 2D part drawings. In previous work, the authors proposed a method to automatically decompose 2D assembly drawings into 3D part drawings, from which 2D part drawings can be easily generated. However, one problem with the proposed method was that the number of solutions could easily explode if the 2D assembly drawings became complex. Building on this work, here we describe a new method to automatically convert 2D assembly drawings to 3D part drawings, generating a unique solution for designers regardless of the complexity of the original 2D assembly drawings. The only requirement for the approach is that the assembly drawings consist of standard parts such as bars and plates. In 2D assembly drawings, the dimensions, part numbers and parts lists are usually drawn, and the proposed method utilizes these to obtain a unique solution. 相似文献
10.
BP神经网络权值初始值与收敛性问题研究 总被引:25,自引:2,他引:25
BP神经网络的收敛性问题是一直受到广泛关注的问题。本文针对BP网络在运算过程中陷入局部最小区,收敛速度慢的问题,从BP算法的原理出发,讨论了权值初始值对网络训练速度的强烈影响(仿真结果证明了这一点),并提出了解决方法。 相似文献