全文获取类型
收费全文 | 3815篇 |
免费 | 80篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 40篇 |
综合类 | 4篇 |
化学工业 | 833篇 |
金属工艺 | 89篇 |
机械仪表 | 81篇 |
建筑科学 | 154篇 |
矿业工程 | 12篇 |
能源动力 | 89篇 |
轻工业 | 305篇 |
水利工程 | 27篇 |
石油天然气 | 12篇 |
武器工业 | 2篇 |
无线电 | 347篇 |
一般工业技术 | 600篇 |
冶金工业 | 673篇 |
原子能技术 | 41篇 |
自动化技术 | 589篇 |
出版年
2021年 | 40篇 |
2020年 | 33篇 |
2019年 | 40篇 |
2018年 | 63篇 |
2017年 | 46篇 |
2016年 | 56篇 |
2015年 | 45篇 |
2014年 | 98篇 |
2013年 | 219篇 |
2012年 | 135篇 |
2011年 | 187篇 |
2010年 | 120篇 |
2009年 | 135篇 |
2008年 | 180篇 |
2007年 | 141篇 |
2006年 | 140篇 |
2005年 | 131篇 |
2004年 | 104篇 |
2003年 | 96篇 |
2002年 | 105篇 |
2001年 | 64篇 |
2000年 | 71篇 |
1999年 | 67篇 |
1998年 | 157篇 |
1997年 | 94篇 |
1996年 | 82篇 |
1995年 | 68篇 |
1994年 | 50篇 |
1993年 | 63篇 |
1992年 | 39篇 |
1991年 | 52篇 |
1990年 | 46篇 |
1989年 | 37篇 |
1988年 | 39篇 |
1987年 | 41篇 |
1986年 | 62篇 |
1985年 | 51篇 |
1984年 | 46篇 |
1983年 | 48篇 |
1982年 | 40篇 |
1981年 | 53篇 |
1980年 | 43篇 |
1979年 | 42篇 |
1978年 | 39篇 |
1977年 | 43篇 |
1976年 | 38篇 |
1975年 | 34篇 |
1973年 | 24篇 |
1972年 | 24篇 |
1971年 | 24篇 |
排序方式: 共有3898条查询结果,搜索用时 15 毫秒
31.
Bernard Williams 《Metal Powder Report》2003,58(10):27-28
With commercially available PIM feedstock reportedly unable to fulfill the requirements for the microPIM components under investigation, researchers at the Institute for Materials Research III (IMR) in Karlsruhe, Germany, have developed new binder systems for feedstock based on both nanoceramic and ultrafine metallic powders. In the case of ceramics (zirconia) the powders can be as fine as 300 nm, and for metals in the 3μm-5μm particle size range. The powders are used to develop PIM gearwheels (Figure 1) and other components for a demonstrator micro annular gear pump design (Figure 2); however, the technology is also said to be applicable to micro gears used in watches. 相似文献
32.
Bernard Chazelle 《Acta Informatica》1987,24(5):565-582
Summary There are many efficient ways of searching a set when all its elements can be represented in memory. Often, however, the domain of the search is too large to have each element stored separately, and some implicit representation must be used. Whether it is still possible to search efficiently in these conditions is the underlying theme of this paper. We look at several occurrences of this problem in computational geometry and we propose various lines of attack. In the course of doing so, we improve the solutions of several specific problems; for example, computing order statistics, performing polygonal range searching, testing algebraic predicates, etc. 相似文献
33.
Effects of dietary trielaidin upon the alkenyl chain profile of plasmalogens were studied using heart mitochondria of rats
fed a semi-purified diet containing 10% of fat supplement in which elaidic acid accounted for 69% of total fatty acids. Alkyl
substituted dioxane (ASD) derivatives of the alkenyl groups of plasmalogens were prepared and analyzed by silver nitrate TLC
and by GLC on different phases (BDS and OV-275). After two months of feeding the experimental diet, 40% of the ASD contained
atrans-octadecenyl chain, suggesting that dietary elaidic acid was reduced in vivo to the corresponding alcohol and incorporated
into plasmalogens. There was a simultaneous decrease in the percentage of ASD containing saturated chains, but the percentage
of ASD substituted withcis-octadecenyl chains was not significantly affected. These observations suggested that elaidic acid may compete with saturated
fatty acids, but not withcis-octadecenoic acids during the plasmalogen biosynthesis. Feeding trielaidin did not seem to have any significant influence
on the relative proportions of plasmalogens, which accounted for 11–12%, on a phosphorus basis, of total heart mitochondria
phospholipids. 相似文献
34.
Surendra P. Verma Jean R. Philippot Bernard Bonnet Josette Sainte-Marie Yves Moschetto Donald F. H. Wallach 《Lipids》1985,20(12):890-896
Raman and resonance Raman spectra of plasma lipoproteins ± malondialdehyde were studied at concentrations which block the
normal receptor-mediated uptake by cells. The strong resonance Raman bands at about 1010, 1162 and 1530 cm−1, due to the presence of carotenoids in the lipoproteins, are envisaged as structural probes. High resolution resonance Raman
spectra of the 1500–1600 cm−1 region reveal multiple features suggesting the coexistence of several structural populations of β-carotene whose precise
assignment is complex. When plasma lipoproteins are reacted with malondialdehyde, a complex change occurs in the resonance
Raman banding of β-carotene in the 1500–1600 cm−1 region. Malonaldehyde (MDA) also modifies the acoustical region (70–200 cm−1 of low density lipoprotein (LDL) lipids. We suggest that malondialdehyde association with plasma lipoproteins alters the
lipid structure via apoprotein or apoprotein/lipid associations. 相似文献
35.
Witold Brostow Bernard Bujard Patrick E. Cassidy Haley E. Hagg Pablo E. Montemartini 《Materials Research Innovations》2002,6(1):7-12
Samples were prepared by addition of a fluorinated poly(aryl ether ketone) (12F-PEK) to a commercial epoxy resin and curing
at either 24 °C or 70 °C. The concentrations of fluoropolymer in the samples were 0, 5, 10, 20, 30, 40, and 50%. Phase inversion
facilitates the formation of more and more smooth surfaces for scratch testing with increasing fluoropolymer concentration.
A progressively increasing load from 0.03 N to 12 N was administered with a diamond tip to the surfaces of the samples; depths
were determined within ±7.5 nm. The original scratch depth is a function of the fluoropolymer concentration. Scratch recovery
(healing) reaches values up to 95%. Plots of the residual depth versus concentration of the fluoropolymer at 4, 6, 8, and
10 N reveal minima for all forces and both temperatures. Addition of only 5% or 10% 12F-PEK improves the scratch recovery
significantly. The results are explained by changes of material morphology with the fluoropolymer concentration.
Electronic Publication 相似文献
36.
37.
Krieshok Thomas S.; Arnold John J.; Kuperman Bernard D.; Schmitz Nancy K. 《Canadian Metallurgical Quarterly》1988,35(2):211
We respond to Cochran's critique of our 1986 study, which was in part a replication of Cochran's original grid methodology for the study of career values. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
38.
This paper presents a new massively parallel MIMD architecture, halfway between the Connection Machine and hypercubes based on 32-bit processors. It is built from specific 8-bit processors arranged in a 2-D grid and communicating by message transfers. We discuss the communication problems, the instruction set of the basic processing unit, the programmation of the whole array and the use of a high level data-flow language. 相似文献
39.
Paul Camion Bernard Courteau Philippe Delsarte 《Applicable Algebra in Engineering, Communication and Computing》1992,2(3):147-162
The concept of the combinatorial matrix of an unrestricted code and the notion of anr-partition design admitted by a code are introduced and discussed in detail. The theory includes a characterization of completely regular codes, and a combinatorial interpretation of the fact that the distinct rows of the distance distribution matrix of a code are linearly independent. In general, it is possible to compute the distance distribution matrix of any code admitting a given partition design by solving a well-defined system of linear equations; this is an efficient technique provided the number of classes in the partition is relatively small. 相似文献
40.
André Girard Pierre Dominique Lansard Bernard Liau Anne Marie Mongeon Jean Luc Thibault 《电信纪事》1991,46(5-6):335-350
Classical hierarchical routing in telephone networks is extended to a wider class called out-of-chain routing in such a way that some useful properties of hierarchical routing are retained. This new routing pattern offers more potential paths than the fixed hierarchical one and can be introduced as a dynamic routing where the fixed alternate sequences change at some predetermined instants during the day. The effect of this new routing pattern on the network performances is examined. The main topic of this paper is to present heuristic methods used to optimise such routings in large networks. We show on artificial networks that the throughput of a given network can be significantly improved by suitable routing choices. We demonstrate that the integration of routing changes within a multihour dimensioning process is possible but the lack of realistic data does not permit at this time to quantify the value of routing optimization on real networks. 相似文献