全文获取类型
收费全文 | 801篇 |
免费 | 30篇 |
学科分类
工业技术 | 831篇 |
出版年
2023年 | 4篇 |
2022年 | 12篇 |
2021年 | 20篇 |
2020年 | 7篇 |
2019年 | 13篇 |
2018年 | 14篇 |
2017年 | 17篇 |
2016年 | 20篇 |
2015年 | 21篇 |
2014年 | 20篇 |
2013年 | 44篇 |
2012年 | 51篇 |
2011年 | 76篇 |
2010年 | 65篇 |
2009年 | 59篇 |
2008年 | 58篇 |
2007年 | 52篇 |
2006年 | 33篇 |
2005年 | 37篇 |
2004年 | 28篇 |
2003年 | 25篇 |
2002年 | 26篇 |
2001年 | 11篇 |
2000年 | 4篇 |
1999年 | 13篇 |
1998年 | 13篇 |
1997年 | 8篇 |
1996年 | 9篇 |
1995年 | 9篇 |
1994年 | 4篇 |
1993年 | 8篇 |
1992年 | 5篇 |
1991年 | 3篇 |
1990年 | 4篇 |
1989年 | 4篇 |
1988年 | 2篇 |
1987年 | 7篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1984年 | 5篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 3篇 |
1976年 | 2篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1963年 | 1篇 |
排序方式: 共有831条查询结果,搜索用时 15 毫秒
1.
Here, we report on the application of corroles as analytically active compounds in liquid membrane electrodes (ISE) that are sensitive towards salicylic acid and salicylate.The potentiometric signals generated by corrole-incorporated ISEs strongly depend on the pH of the aqueous sample solution and the membrane composition, such as the presence of lipophilic sites. Corrole incorporating ISEs are characterised by a low detection limit (4.0 × 10−5 M) and a wide linear range (4.0 × 10−5 to 5.3 × 10−3 M). Also, they are free from interference versus other organic anions.The mechanism of the generation of the potentiometric signals of corrole incorporating ISEs in the presence of salicylate anion, as well salicylic acid, will be discussed. 相似文献
2.
Marcela Brugnach Andrew Tagg Florian Keil Wim J. de Lange 《Water Resources Management》2007,21(7):1075-1090
The use of computer models offers a general and flexible framework that can help to deal with some of the complexities and
difficulties associated with the development of water management plans as prescribed by the Water Framework Directive. However,
despite the advantages modelling presents, the integration of information derived from models into policy is far away from
being trivial or the norm. Part of the difficulties of this integration is rooted in the lack of confidence policy makers
have on the incorporation of modelling information into policy formulation. In this paper we examine the reasons for this
apparent lack of confidence and explore how some tools, presently in use, address this problem. We conclude that public confidence
in models is highly dependent on the way uncertainties are addressed and suggest possible directions of action to improve
the current situation. Four real case studies illustrate how computer models have been used in The Netherlands for carrying
out management plans at regional and national scale. We suggest that the solution to integrate modelling information into
policy formulation lies on both the modelling and the policy-making communities. 相似文献
3.
Wim H. Hesselink 《Acta Informatica》2007,44(2):123-151
Concurrent and reactive programs are specified by their behaviours in the presence of a nondeterministic environment. In a
natural way, this gives a specification (ARW) of an atomic variable in the style of Abadi and Lamport. Several implementations of atomic variables by lower level primitives
are known. A few years ago, we formulated a criterion to prove the correctness of such implementations. The proof of correctness
of the criterion itself was based on Lynch’s definition of atomicity by serialization points. Here, this criterion is reformulated
as a specification HRW in the formal sense. Simulations from HRW to ARW and vice versa are constructed. These now serve as a constructive proof of correctness of the criterion. Eternity variables
are used in the simulation from HRW to ARW. We propose so-called gliding simulations to deal with the problems that appear when occasionally the concrete implementation
needs fewer steps than the abstract specification. 相似文献
4.
5.
6.
Liquid propylene was polymerized in a 5‐L autoclave batch reactor using a commercially available TiCl4/MgCl2/Al(ethyl)3/DCPDMS Ziegler–Natta catalyst, with a phthalate ester as internal electron donor. The powders from these polymerizations were characterized using laser diffraction particle size distribution (PSD) analysis, scanning electron microscopy (SEM), and bulk density measurements. These characteristics were analyzed as a function of the process conditions, including hydrogen and monomer concentration, polymerization temperature, and the prepolymerization method. It was shown that polymerization temperature influences the powder morphology to a large extent. At low temperatures, high‐density particles were obtained, showing regular shaped particle surfaces and low porosities. With increasing temperature, the morphology gradually was transferred into a more open structure, with irregular surfaces and poor replication of the shape of the catalyst particle. When using a prepolymerization step at a relatively low temperature, the morphology obtained was determined by this prepolymerization step and was independent from conditions in main polymerization. The morphology obtained was the same as that observed after a full polymerization at temperature. Even when using a short polymerization at an increasing temperature, the morphology was strongly influenced by the initial conditions. The effect of variation in hydrogen concentration supported the conclusion that the initial polymerization rate determines the powder morphology. In the absence of hydrogen, high bulk densities, and regularly shaped particles were obtained, even at high temperatures. With increasing hydrogen concentration, the reaction rates increased rapidly, and with that changed the morphology. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1421–1435, 2003 相似文献
7.
Biodegradable Microparticles for Simultaneous Detection of Counterfeit and Deteriorated Edible Products 下载免费PDF全文
Ivan Rehor Sophie van Vreeswijk Tina Vermonden Wim E. Hennink Willem K. Kegel Huseyin Burak Eral 《Small (Weinheim an der Bergstrasse, Germany)》2017,13(39)
In an era of globalized trade relations where food and pharmaceutical products cross borders effortlessly, consumers face counterfeit and deteriorated products at elevated rates. This paper presents multifunctional, biodegradable hydrogel microparticles that can provide information on the authenticity and the potential deterioration of the tagged food or pharmaceutical formulations. These microparticles integrate spatially patterned authenticity code with two sensors—the first one detects possible presence of pathogenic microbes through monitoring pH while the second one identifies products stored above optimal temperatures via optical monitoring of the microparticle degradation. Particles are synthesized from a biocompatible polymer and a photoinitiator, dextran modified with 2‐hydroxyethylmethacrylate and riboflavin, respectively, using a continuous, high throughput method stop‐flow lithography. The proposed synthesis approach also enables crosslinking with visible light bringing about additional flexibility to flow lithography. Model liquid and solid food and pharmaceutical products are successfully labeled with microparticles and the functionality of the sensors in aqueous solutions is demonstrated. 相似文献
8.
Pankaj R. Jaiswal R. Iyer Kumar Thibault Juwet Geert Luyckx Cedric Verhaeghe Wim De Waele 《Strain》2023,59(2):e12433
The strength and deformation of full-scale adhesively bonded multi-material joints is studied in this paper. Four joints with a thick layer of methyl methacrylate adhesive (MMA) have been manufactured in shipyard conditions. In two specimens, cracks have been introduced at steel–adhesive and composite–adhesive interfaces. One cracked and one un-cracked specimen were subjected to quasi-static tensile testing; the two remaining specimens were stepwise loaded/unloaded with increasing load until failure. The strain in the adhesive layers was measured with digital image correlation (DIC). This showed a predominant shear deformation and dissimilar shear strain patterns for different bond lines. Fibre Bragg (FBG) sensors were used to monitor strains at steel and composite constituents and to detect the onset and evolution of damage in the un-cracked specimen. Strains measured by FBG sensors correspond well with DIC results at nearby regions. All specimens failed by delamination of the composite panel near the composite–adhesive interface. 相似文献
9.
Fast simulation (e.g., real-time) of flexible multibody systems is typically restricted by the presence of both differential
and algebraic equations in the model equations, and the number of degrees of freedom required to accurately model flexibility.
Model reduction techniques can alleviate the problem, although the classically used body-level model reduction and general-purpose
system-level techniques do not eliminate the algebraic equations and do not necessarily result in optimal dimension reduction.
In this research, Global Modal Parametrization, a model reduction technique for flexible multibody systems is further developed
to speed up simulation of flexible multibody systems. The reduction of the model is achieved by projection on a curvilinear
subspace instead of the classically used fixed vector space, requiring significantly less degrees of freedom to represent
the system dynamics with the same level of accuracy. The numerical experiment in this paper illustrates previously unexposed
sources of approximation error: (1) the rigid body motion is computed in a forward dynamical analysis resulting in a small
divergence of the rigid body motion, and (2) the errors resulting from the transformation from the modal degrees of freedom
of the reduced model back to the original degrees of freedom. The effect of the configuration space discretization coarseness
on the different approximation error sources is investigated. The trade-offs to be defined by the user to control these approximation
errors are explained. 相似文献
10.
A new elegant and simple algorithm for mutual exclusion of N processes is proposed. It only requires shared variables in a memory model where shared variables need not be accessed atomically.
We prove mutual exclusion by reformulating the algorithm as a transition system (automaton), and applying simulation of automata.
The proof has been verified with the higher-order interactive theorem prover PVS. Under an additional atomicity assumption,
the algorithm is starvation free, and we conjecture that no competing process is passed by any other process more than once.
This conjecture was verified by model checking for systems with at most five processes. 相似文献