全文获取类型
收费全文 | 2501篇 |
免费 | 85篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 24篇 |
综合类 | 19篇 |
化学工业 | 893篇 |
金属工艺 | 38篇 |
机械仪表 | 44篇 |
建筑科学 | 146篇 |
矿业工程 | 4篇 |
能源动力 | 62篇 |
轻工业 | 126篇 |
水利工程 | 5篇 |
石油天然气 | 3篇 |
无线电 | 96篇 |
一般工业技术 | 434篇 |
冶金工业 | 354篇 |
原子能技术 | 25篇 |
自动化技术 | 315篇 |
出版年
2022年 | 20篇 |
2021年 | 24篇 |
2019年 | 30篇 |
2018年 | 27篇 |
2017年 | 28篇 |
2016年 | 49篇 |
2015年 | 60篇 |
2014年 | 68篇 |
2013年 | 98篇 |
2012年 | 109篇 |
2011年 | 114篇 |
2010年 | 92篇 |
2009年 | 97篇 |
2008年 | 113篇 |
2007年 | 95篇 |
2006年 | 95篇 |
2005年 | 79篇 |
2004年 | 77篇 |
2003年 | 53篇 |
2002年 | 58篇 |
2001年 | 55篇 |
2000年 | 52篇 |
1999年 | 68篇 |
1998年 | 90篇 |
1997年 | 59篇 |
1996年 | 50篇 |
1995年 | 45篇 |
1994年 | 44篇 |
1993年 | 29篇 |
1992年 | 37篇 |
1991年 | 40篇 |
1990年 | 32篇 |
1989年 | 47篇 |
1988年 | 29篇 |
1987年 | 31篇 |
1985年 | 19篇 |
1984年 | 20篇 |
1983年 | 30篇 |
1982年 | 25篇 |
1981年 | 22篇 |
1980年 | 24篇 |
1979年 | 22篇 |
1978年 | 35篇 |
1977年 | 29篇 |
1976年 | 27篇 |
1975年 | 31篇 |
1974年 | 34篇 |
1973年 | 32篇 |
1971年 | 19篇 |
1970年 | 21篇 |
排序方式: 共有2588条查询结果,搜索用时 15 毫秒
1.
Ohne Zusammenfassung
The online version of the original article can be found under doi:. 相似文献
2.
Dieter Oswald 《真空研究与实践》1996,8(2):88-91
All vacuumpummps which use a liquid as a sealing-agent have to take care of their specific demands. In this paper liquid-ring-vacuum-pumps will be short mentioned, because the user is familiar with this pumps and alternative fluids. Using other fluids in other mecanical vacuumpumps are not in operation in the field of the various applications frequently. You will find some ideas for using other fluids which are possibly used in rotary-vane vacuum-pumps to find more consideration in the future. 相似文献
3.
Maurus Biedermann Konrad Grob Dieter Fr?hlich Werner Meier 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1992,195(5):409-416
Summary On-line coupled liquid chromatography-gas chromatography-flame ionisation detection (LC-GC-FID) enables efficient and unambiguous determination of irradiation for some fat-containing foods (e.g. meat). Other products, however, contain interfering components or are contaminated, e.g., with mineral oil. Since more selective detection by mass spectrometry has limited success, the determination was improved by a more selective isolation of some key components among the fat degradation products, e.g. the dienes or trienes, by LC-LC-GC-FID. Applications are shown for soup mixes, some spices, fish, and shrimps.
Nachweis der Bestrahlung fetthaltiger Lebensmittel durch direkt gekoppelte LC-GC und LC-LC-GC
Zusammenfassung Die Bestrahlung einiger fetthaltiger Lebensmittel, z. B. Fleisch, kann mit direkt gekoppelter LC-GC-FID rationell und eindeutig nachgewiesen werden. In anderen Proben wird die Analyse aber durch Inhaltsstoffe des Produktes oder durch Verunreinigungen (z. B. mit Mineralöl) gestört. Da selektivere Detektion durch Massenspektrqmetrie wenig verspricht, wurde der Nachweis durch selektivere Isolierung von Schlüsselkomponenten unter den Bestrahlungsprodukten, z. B. der Diene oder Triene, mittels LC-LC-GC yerbessert. Anwendungen werden gezeigt für Suppenpulver, einige Gewürze, Fisch und Garnelen.相似文献
4.
5.
Dieter Braun Manfred Rtzsch Peter Fiedler Günter Weber Heinz Hofmann Bernd Gutschalk 《大分子材料与工程》1991,187(1):101-121
Based on the example of PE-LD grades and on model substances obtained by preparative fractionation (fractions in the molecular weight range M?w = 1.2 ? 390·104 g/mol), comprehensive investigations regarding the problems of structure/properties have been carried out. The correlations of M?w with 15 physical and application technological perameters have been investigated taking into account the reaction mechanism during the manufacturing of PE-LD in the tubular and agitated autoclave reactor, resulting in the formation of so-called primary structure perameters M?n, M?w, molar mass distribution, short chain branching and long chain branching. For the interpretation of the results, among other factors, also the morphological conditions have been taken into consideration, which in connection with the molecular parameters reveal — for specific M?w-ranges — strong changes and saturation ranges, resp., for the physical and application technological properties. 相似文献
6.
7.
The dependence of the critical concentration of the ternary system polymer-polymer-solvent on the molecular weight can be expressed by the relation where cc is the critical concentration, M? the appropriate average of the molecular weight of both polymers; A and cc∞ are constants for the given system. The possibility of determining the molecular weight of one of the polymers from the value cc and the molecular weight of the known polymer with the aid of equation (1) is discussed. 相似文献
8.
We present a novel approach to the automated marking of student programming assignments. Our technique quantifies the structural similarity between unmarked student submissions and marked solutions, and is the basis by which we assign marks. This is accomplished through an efficient novel graph similarity measure (AssignSim). Our experiments show good correlation of assigned marks with that of a human marker. 相似文献
9.
An accurate acceptance-rejection algorithm is devised and tested. The procedure requires an average of less than 3 uniform deviates whenever the standard deviation of the distribution is at least 4, and this number decreases monotonically to 2.63 as . Variable parameters are permitted, and no subroutines for sampling from other statistical distributions are needed.This research was supported by the Austrian Research Council (Fonds zur Förderung der wissenschaftlichen Forschung). 相似文献
10.
The stability region of the helical textures in3He-A in thev
s-H phase diagram is theoretically determined. Herev
sis the superflow velocity andH (v
s) is the external magnetic field. The pitch of the helixk
–1 that minimizes the Gibbs free energy and the corresponding inclination angles ofl andd are determined numerically as functions ofv
sandH. The NMR frequencies (two longitudinal and four transverse frequencies) associated with the helical texture are obtained.Work supported by the National Science Foundation under Grant No. DMR 76-21032. 相似文献