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921.
Luigi Catuogno Roberto Gassirà Michele Masullo Ivan Visconti 《Information Security Technical Report》2013,17(3):93-104
A smart card is a tamper-resistant miniature computer that performs some basic computations on input a secret information. So far, smart cards have been widely used for securing many digital transactions (e.g., pay television, ATM machines).We focus on the implementation of operating system security services leveraging on smart cards. This very challenging feature allows one to personalize some functionalities of the operating system by simply changing a smart card. Current solutions for integrating smart card features in operating system services require at least a partial execution of some of the operating system functionalities at “user level”. Unfortunately, system functionalities built on top of components lying at both kernel and user levels may negatively affect the overall system security, due to the introduction of multiple points of failure.In this work, we present the design and implementation of SmartK: a framework that integrates features of smart cards uniquely in the Linux kernel. In order to validate our approach, we propose a host of enhancements to the Linux operating system built on top of SmartK: 1) in-kernel clients' authentication with Kerberos; 2) execution of trusted code; 3) key management in secure network filesystems.In particular, we present an experimental Linux OS distribution (SalSA), which addresses the security issues related to downloading packages and to updating an operating system through the Internet. 相似文献
922.
Béla Sebők Gábor Kiss Péter J. Szabó Dániel Rigler Milán L. Molnár Gábor Dobos Ferenc Réti Hajnal Szőcs Árpád F. Joób Sándor Bogdán György Szabó 《Journal of materials science. Materials in medicine》2013,24(3):821-828
The long term effect of the human body on a pyrolytic carbon covered C/C composite maxillofacial implant (CarBulatTm) was investigated by comparing the structure, the surface morphology and composition of an implant retrieved after 8 years to a sterilized, but not implanted one. Although the thickness of the carbon fibres constituting the implants did not change during the 8 year period, the surface of the implant retrieved was covered with a thin surface layer not present on the unimplanted implant. The composition of this layer is identical to the composition of the underlying carbon fibres. Calcium can only be detected on the surface as a trace element implying that the new layer is not formed by bone tissue. Residual soft tissue penetrating the bulk material between the carbon fibre bunches was found on the retrieved implant indicating the importance of the surface morphology in tissue growth and adhering to implants. 相似文献
923.
László Gyarmati András Gulyás Balázs Sonkoly Tuan A. Trinh Gergely Biczók 《Computer Networks》2013,57(8):1758-1773
The increasing popularity of both small and large private clouds and expanding public clouds poses new requirements to data center (DC) architectures. First, DC architectures should be incrementally scalable allowing the creation of DCs of arbitrary size with consistent performance characteristics. Second, initial DC deployments should be incrementally expandable supporting small-scale upgrades without decreasing operation efficiency. A DC architecture possessing both properties satisfies the requirement of free-scaling.Recent work in DC design focuses on traditional performance and scalability characteristics, therefore resulting in symmetric topologies whose upgradability is coarse-grained at best. In our earlier work we proposed Scafida, an asymmetric, scale-free network inspired DC topology which scales incrementally and has favorable structural characteristics. In this paper, we build on Scafida and propose a full-fledged DC architecture achieving free-scaling called FScafida. Our main contribution is threefold. First, we propose an organic expansion algorithm for FScafida; this combined with Scafida’s flexible original design results in a freely scalable architecture. Second, we introduce the Effective Source Routing mechanism that provides near-shortest paths, multi-path and multicast capability, and low signaling overhead by exploiting the benefits of the FScafida topology. Third, we show based on extensive simulations and a prototype implementation that FScafida is capable of handling the traffic patterns characteristic of both enterprise and cloud data centers, tolerates network equipment failures to a high degree, and allows for high bisection bandwidth. 相似文献
924.
Julia Armesto Izabela Lubowiecka Celestino Ordóñez Fernando I. Rial 《Automation in Construction》2009,18(5):559-569
The aim of this paper is to present a methodology for the evaluation of historic timber structures, based on numerical modeling coupled with on site measurements. A method to measure the geometry of structural elements of a timber roof using a photogrammetric modeling procedure is described. In particular, we show the utility of photogrammetric based models when applied to structural analysis by directly introducing 3D geometry files in the preprocessing module of computational software based on the Finite Element Method. The 2D and 3D FEM models of the roof are considered to compare the simple and more complex modeling, and static and dynamic analyses are performed. Both models are prepared using the photogrammetric data. 相似文献
925.
The purpose of these field and lab studies undertaken during rehabilitation work being done on an ancient railway line was to characterize a layer of ballast fouled with soil found in the track substructure. The field studies included the characterization of the thickness, grain size distribution and void ratio of the fouled ballast layer, as well as a large number of plate load tests, both on the fouled ballast layer and on the subgrade. The resilient behaviour of the fouled ballast was evaluated in the lab by cyclic triaxial tests on large size reconstituted specimens with distinct fouling indexes (different grain size distribution) and distinct humidity states (dry or wet). The results obtained were used as support for the decision to maintain the fouled ballast layer under the new sub-ballast in a number of stretches of the renewed line. 相似文献
926.
Roberto Chiabrando Enrico Fabrizio Gabriele Garnero 《Renewable & Sustainable Energy Reviews》2009,13(9):2441-2451
The installation and operation of systems that exploit solar energy through photovoltaic conversion, recently promoted in some European countries by new sell-back tariffs, is a relevant transformation of the territory for various reasons (land use, elimination of the existing vegetation, visual impact on the components of the landscape, microclimate change, glare from the reflection of the direct sunlight). The weak energy intensity of the solar source coupled with the low conversion efficiency of the photovoltaic cells, make the physical dimensions of such systems relevant and, with them, also the environmental, territorial and landscape impacts that basically depend on the physical extent of the system. If it is well known that an incentive to the exploitation of renewable sources is one of the features of the policy of land conservation, including the one of the protected areas, at the same time the concerns of local communities and governments about the environmental, territorial and landscape impacts of this technology are increasing rapidly.Given this picture, this work is intended to clarify the territorial impacts of the ground mounted photovoltaic systems. Later, the paper concentrates on a specific impact, which is the assessment of the risk of glare by reflection of direct sunlight from the surfaces of photovoltaic modules. The methodologies that can be used to assess this impact and the outcomes of an evaluation carried out for a 5000 m2 PV system currently designed on a hilly territory in Italy are presented. 相似文献
927.
López Steven R.; Lara Ma. del Carmen; Kopelowicz Alex; Solano Susana; Foncerrada Hector; Aguilera Adrian 《Canadian Metallurgical Quarterly》2009,77(4):763
The authors developed and tested a 35-min psychoeducational program with the goal of increasing Spanish-speaking persons’ literacy of psychosis. The program uses popular cultural icons derived from music, art, and videos, as well as a mnemonic device—La CLAve (The Clue)—to increase (a) knowledge of psychosis, (b) efficacy beliefs that one can identify psychosis in others, (c) attributions to mental illness, and (d) professional help-seeking. Assessments were conducted before and after administering the program to both community residents (n = 57) and family caregivers of persons with schizophrenia (n = 38). For community residents, the authors observed increases across the 4 domains of symptom knowledge, efficacy beliefs, illness attributions, and recommended help-seeking. For caregivers, increases were observed in symptom knowledge and efficacy beliefs. La CLAve is a conceptually informed psychoeducational tool with a developing empirical base aimed at helping Spanish-speaking Latinos with serious mental illness obtain care in a timely manner. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
928.
Francisco López-Carrasquero Giuseppe Giammanco Angélica Díaz Johanna Dávila Carlos Torres Estrella Laredo 《Polymer Bulletin》2009,63(1):69-78
A series of comb like poly(p-n-alkylstyrene)s with linear alkyl groups, containing even numbers of carbon atoms from 12 up to 22 were synthesized by radical
polymerization and characterized by FTIR, 1H NMR, TGA, TVA DSC, and WAXS. All polymers were obtained in good yields and were soluble in organic solvents as chloroform,
dichloromethane or tetrahydrofuran and insoluble in methanol; they are stable up to temperatures near 300 °C. On the other
hand, the alkylic side chains of all series are able to crystallize in a paraffinic phase in which the melting temperature
and enthalpy increase with the methylene number of the n-alkyl chain. 相似文献
929.
The effect of copper addition in the microstructure of sol–gel titanium oxide (TiO2) supported on anodic aluminum oxide (AAO) membranes is reported. Two deposition methods based on immersion and flow techniques
were used for the coating of the porous AAO membrane. Copper-free membranes were studied as a function of different ratios
of H+/Ti, H2O/Ti, selecting the most appropriate for the sensitization with copper. For copper-doped TiO2 arrays, the presence of copper causes the reduction of grain size and enhances titania deposition inside the AAO pores, although
no clear tendency with copper content was found. The formation of copper-doped titania nanotubes was validated after dissolving
the AAO membranes, finding a deposition-dependent stability in the Cu-doped materials. Titania and Cu-doped titania nanotubes
analyzed as colloidal solutions show band gaps substantially shifted to the red in comparison to the direct band gap of near-spherical
colloidal materials. These arrays are important for photocatalysis and for the development of third generation photovoltaic
devices. 相似文献
930.
J. F. Román-Zamorano M. Flores-Acosta H. Arizpe-Chávez F. F. Castillón-Barraza M. H. Farías R. Ramírez-Bon 《Journal of Materials Science》2009,44(18):4781-4788
We have synthesized lead and lead sulfide nanoparticles embedded in a natural zeolite (clinoptilolite) matrix by a simple
hydrothermal process. The process steps involve the partial removing of the natural cations in clinoptilolite, the ion-exchange
process to enclose Pb ions and nanoparticles and finally a sulfuration process at different temperatures to obtain lead sulfide
phases in the zeolite matrix. The samples were studied by X-ray diffraction, diffuse reflectance spectroscopy, energy dispersive
X-ray spectroscopy, X-ray photon spectroscopy and transmission electron microscopy. The experimental results show the inclusion
of three Pb species with different valence states after the Pb ion-exchange step, namely Pb2+, Pb4+, and Pb0. At the end of the process, two simultaneous lead sulfide crystalline phases, PbS (Galena) and PbS2 (tetragonal) were synthesized in the clinoptilolite matrix. The optical absorption spectra of the samples show the exciton
absorption peaks typical of colloidal PbS nanoparticles. The average size of the PbS nanoparticles was about 10 nm and their
crystalline structure was determined from diffraction electron patterns. The high-pressure phase PbS2 was also identified and its formation was attributed to the influence of the special conditions of clinoptilolite matrix
as crystallization media to induce some selective nucleation process of this crystalline phase. 相似文献