全文获取类型
收费全文 | 5134篇 |
免费 | 340篇 |
国内免费 | 14篇 |
专业分类
电工技术 | 146篇 |
综合类 | 30篇 |
化学工业 | 1198篇 |
金属工艺 | 179篇 |
机械仪表 | 128篇 |
建筑科学 | 138篇 |
矿业工程 | 30篇 |
能源动力 | 183篇 |
轻工业 | 771篇 |
水利工程 | 53篇 |
石油天然气 | 27篇 |
武器工业 | 1篇 |
无线电 | 312篇 |
一般工业技术 | 1069篇 |
冶金工业 | 216篇 |
原子能技术 | 93篇 |
自动化技术 | 914篇 |
出版年
2023年 | 48篇 |
2022年 | 53篇 |
2021年 | 139篇 |
2020年 | 112篇 |
2019年 | 138篇 |
2018年 | 213篇 |
2017年 | 205篇 |
2016年 | 206篇 |
2015年 | 187篇 |
2014年 | 268篇 |
2013年 | 518篇 |
2012年 | 344篇 |
2011年 | 443篇 |
2010年 | 336篇 |
2009年 | 283篇 |
2008年 | 179篇 |
2007年 | 164篇 |
2006年 | 89篇 |
2005年 | 131篇 |
2004年 | 88篇 |
2003年 | 86篇 |
2002年 | 117篇 |
2001年 | 87篇 |
2000年 | 66篇 |
1999年 | 48篇 |
1998年 | 78篇 |
1997年 | 70篇 |
1996年 | 52篇 |
1995年 | 45篇 |
1994年 | 35篇 |
1993年 | 37篇 |
1992年 | 30篇 |
1991年 | 24篇 |
1990年 | 21篇 |
1989年 | 24篇 |
1988年 | 19篇 |
1986年 | 18篇 |
1985年 | 27篇 |
1984年 | 37篇 |
1983年 | 29篇 |
1982年 | 25篇 |
1981年 | 42篇 |
1980年 | 30篇 |
1979年 | 33篇 |
1978年 | 28篇 |
1977年 | 26篇 |
1976年 | 44篇 |
1975年 | 25篇 |
1974年 | 20篇 |
1973年 | 33篇 |
排序方式: 共有5488条查询结果,搜索用时 14 毫秒
11.
12.
13.
Ivan Fortelný Monika Lapčíková František Lednický Zdeněk Starý Zdeněk Kruliš 《Polymer Engineering and Science》2008,48(3):564-571
This article is focused on the phase structure development in immiscible polymer blends during melt mixing. Nonuniformity of the phase structure, i.e., the coexistence of areas containing particles with markedly different size distribution, was detected in quenched and compression molded samples of a number of various blends prepared by long and intensive mixing in the chamber of a Plasticorder. The same effect was found also for polystyrene/polyamide blends prepared in a twin‐screw extruder. It was shown that neglecting nonuniformity of the phase structure can lead to considerable error in evaluation of the effect of system parameters on the blend morphology. The reasons for the effect were discussed and it was found that inhomogeneous flow field in mixers is a plausible explanation of the nonuniform phase structure. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers 相似文献
14.
Ohne Zusammenfassung 相似文献
15.
Mariana Ušáková Jozef Lukáč Rastislav Dosoudil Vladimír Jančárik Anna Grusková Elemír Ušák Jozef Sláma Jan Šubrt 《Journal of Materials Science: Materials in Electronics》2007,18(12):1183-1189
The paper is devoted to the preparation of NiZn ferrite with small substitutions of copper by means of ceramic technology.
The influence of small Cu substitution on the microstructural and magnetic properties of NiZn ferrites have been analysed
by means of various experimental methods and interpreted from the point of view of preparation technology optimisation and
possible applications of such materials. A strong correlation between the substituent content and resulting properties has
been observed, thus allowing preparation of material with the properties tailored for any particular application. 相似文献
16.
Novolac-type polycondensation of benzaldehyde (B) and pyrogallol (P) has been carried out at 60°C, 75°C and 90°C and at B/P mole ratios of 1.5 and 3.0 using phosphoric acid as catalyst. The reaction follows a 2nd order rate law. By using GC consumption data of benzaldehyde and pyrogallol, kinetic parameters such as the overall rate constants, activation energies (Ea) and logA values are investigated. The activation energies for 1.5 and 3.0 B/P mole ratios are found as 62.3 kJ mol?1 and 56.4 kJ mol?1, respectively. The molecular weights of the resins determined by measuring intrinsic viscosities (25°C, THF) are in the range of 0.03 to 0.07 dL g?1 at various temperatures and B/P mole ratios. 相似文献
17.
What are the key elements of a sustainable university? 总被引:1,自引:0,他引:1
Nowadays, the principles of sustainable development are becoming increasingly important and universities are acting as agents
in promoting these principles within society. In the future, universities will inevitably play crucial role in propagating
these principles. This paper highlights important documents and discusses definitions of the term education for sustainable development. Elements, based on continuous feedback loop (Deming spiral) are discussed, in order to incorporate sustainability principles
into university activities. The University of Maribor has been used as a case study to test the effectiveness of the proposed
integration of sustainable development principles. 相似文献
18.
Jiři Gregor 《Mathematics of Control, Signals, and Systems (MCSS)》1991,4(2):205-215
A significant part of the theory of one-dimensional linear shift-invariant systems is based on the concept of weighting function
(or impulse response): the output is the convolution of the weighting function with the input. This paper introduces the concept
of linear translation-invariant systems and uses this notion in studying impulse response, z-transforms, and transfer functions
for multidimensional systems. 相似文献
19.
This paper addresses one of the central problems arising at the transfer stage in machine translation: syntactic mismatches,
that is, mismatches between a source-language sentence structure and its equivalent target-language sentence structure. The
level at which we assume the transfer to be carried out is the Deep-Syntactic Structure (DSyntS) as proposed in the Meaning-Text Theory (MTT). DSyntS is abstract enough to avoid all types of divergences that result
either from restricted lexical co-occurrence or from surface-syntactic discrepancies between languages. As for the remaining
types of syntactic divergences, all of them occur not only interlinguistically, but also intralinguistically; this means that
establishing correspondences between semantically equivalent expressions of the source and target languages that diverge with
respect to their syntactic structure is nothing else than paraphrasing. This allows us to adapt the powerful intralinguistic
paraphrasing mechanism developed in MTT for purposes of interlinguistic transfer. 相似文献
20.
Coupling GIS with Hydrologic and Hydraulic Flood Modelling 总被引:6,自引:1,他引:5
Nunes Correia Francisco Castro Rego Filipe Da Grača Saraiva Maria Ramos Isabel 《Water Resources Management》1998,12(3):229-249
Geographic Information Systems (GIS) have been recognised as a powerful means to integrate and analyse data from various sources in the context of comprehensive floodplain management. As part of this comprehensive approach to floodplain management, it is very important to be able to predict the consequences of different scenarios in terms of flooded areas and associated risk. Hydrologic and hydraulic modelling plays a crucial role and there is much to gain in incorporating these modelling capabilities in GIS. This is still a rather complex task and research is being done on the full integration of these models. Interfacing between these models and GIS may be a very efficient way of overcoming the difficulties and getting very good results in terms of engineering practice. This paper presents results based on the use of Intergraph GIS coupled with Idrisi GIS. Using these two systems substantially increased the flexibility of using GIS as a tool for flood studies. A lumped (XSRAIN) and a distributed (OMEGA) hydrologic models were used to simulate flood hydrographs. The well known HEC-2 Hydraulic model was used to compute flooded areas. These models were applied in the Livramento catchment with very good results. The computation of flooded areas for different flood scenarios, and its representation in GIS, can be used in the assessment of affected property and associated damages. This is a very useful GIS-based approach to floodplain management. 相似文献