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991.
The relationship between microstructure and cleavage resistance in quenched and tempered high-strength bainitic and martensitic steels is investigated by means of Charpy-V tests, uniaxial tensile test on unnotched specimens and electron back scattered diffraction (EBSD). Steels under investigation are low/medium carbon (C = 0.10-0.40%) steels with yield strength in the range YS = 500-1000 MPa.Results show that the tensile strength and the cleavage resistance of quenched and tempered (Q&T) steels appear to be controlled by different structural parameters and not, as in the case of polygonal ferritic steels, by the same structural unit. In particular, yield strength is controlled by the mean subgrain size, whereas the structural unit controlling the critical cleavage stress is the covariant (bainitic or martensitic) packet, whose size is slightly lower than the average unit crack path (UCP). The critical stage in the fracture process appears to be the propagation of a Griffith crack from one packet to another, and the resistance offered by high-angle boundaries is approximately the same as that of low-C steels with bainitic or polygonal ferrite microstructure. 相似文献
992.
介绍了纤维膜接触器技术及其在顺丁橡胶装置碱洗过程中的应用.与传统的采用液滴混合分散法的油碱精制工艺不同,纤维膜接触器采用了非分散的油碱液膜接触并反应,使油品和碱液快速而高效地分离,不会产生油品和碱液的乳化或携带,提高了碱的利用率.同时,由于它体积小,效率高不需要下游的碱液沉降或水洗设备,节省了投资和占地面积. 相似文献
993.
Eunice Valduga Alexsandra Valério Pihetra Oliveira Tatsch Helen Treichel Agenor Furigo Jr. Marco Di Luccio 《Food and Bioprocess Technology》2009,2(2):234-238
The increasing demand for carotenoids by industries has drawn attention to their bio-production. Since pigments are intracellular,
extraction steps are then needed after cell cultivation. In this work, different strategies for extraction of carotenoid pigments
from Sporidiobolus salmonicolor (CBS 2636) were studied. Different solvents (dimethyl sulfoxide, petroleum ether, hexane, ethyl acetate, chloroform, and
acetone), liquid N2, and diatomaceous earth were used to disrupt the cell and thus release the intracellular carotenoids. The results of this
study showed that when multiple solvents were used, a synergistic effect on the extent of carotenoids recovery was obtained.
Maximum concentration of total carotenoids (913 μg/L) was obtained in the treatment using liquid N2 and dimethyl sulfoxide to disrupt the cell, followed by the extraction with a solution of acetone/methanol (7:3, v/v). 相似文献
994.
Zhu Xiao Di 《Housing Studies》2009,24(3):321-332
Using American Housing Survey (AHS) data, this empirical paper suggests that if someone already has a second home, it may not affect their decision about the price of a new primary home, and they will not be likely to choose a cheaper one than their counterpart without a second home. This runs counter to the implicit suggestion of a previous study that second-home ownership may reduce the demand for primary housing. Many baby boomers have second homes and they have not yet locked up their current primary housing as the final home of their lifetime and may even trade up before they trade down. At present, except for continuous immigration, few other factors point toward growth in housing demand. Thus the finding here can be seen as good news for the housing market when it eventually recovers from its current downturn and crisis in mortgage lending. 相似文献
995.
G.M. Polli L. Reccia A. Cucchiaro A. della Corte A. Di Zenobio L. Muzzi A. Pizzuto G. Ramogida S. Turtú R. Villari M. Nannini C. Portafaix L. Zani P. Barabaschi 《Fusion Engineering and Design》2009,84(7-11):1531-1538
In the framework of the Broader Approach Agreement, Europe is involved in the design activities for the Japanese Tokamak JT-60SA, investigating, among several issues, the operation of the superconducting TF magnets and their subsystems, aimed at the reactor conceptual design definition. In particular, one of the main critical aspects to study is the heating of the conductor due to both direct component of energy deposited by neutrons and by secondary gamma generated during plasma operation, and heat generated by the radiation on casing and transferred to the winding pack. Indeed, the operating temperature and the relevant temperature margin (i.e. the operating safety margin) of the magnet will depend strongly on the heat loads and on the capability of the coolant to remove it. Furthermore, the heat power to the conductor will depend on several aspects, namely the thickness of insulating material, the mass flow rate of helium flowing in the conductors and its thermodynamic properties at operating conditions, and the layout of the superconductors constituting the winding. Moreover, a crucial aspect in the final design will be the presence and position of the casing cooling channels. In this paper a 2D sensitivity analysis of heat transfer from casing to winding pack with respect to cooling channels number and position is presented, based on the reference layout of the magnet. As a result, we evaluated the optimum number and positioning of cooling channels needed, as a trade-off between magnet operating limits and available cryogenic power and if, at limit, they could be even neglected in normal operation, keeping dwell-time within reasonable values. 相似文献
996.
Mauro Epifani Marco Alvisi Luciana Mirenghi Gabriella Leo Pietro Siciliano Lorenzo Vasanelli 《Journal of the American Ceramic Society》2001,84(1):48-54
A chloride-based inorganic sol–gel route was used for preparing pure and metal (osmium, nickel, palladium, platinum)-doped SnO2 sol. SnCl4 was first reacted with propanol, then the resulting compound was hydrolyzed and subsequently mixed with solutions of the metal dopants. The obtained sols were used for depositing thin films by spin coating or for preparing powders by solvent evaporation at 110°C. FTIR spectroscopy and thermal analysis of the powders revealed that chlorine still bound to tin stabilized the sol against gelation by hindering the condensation reactions. Film characterizations showed that platinum and palladium, unlike nickel and osmium, were likely to form nanoparticles in the SnO2 lattice. This result was discussed with regard to the different ways that platinum and palladium, on one hand, and nickel and osmium, on the other, modified the growth of SnO2 grains and the film roughness and morphology. Dopants that formed nanoparticles (platinum, palladium) resulted in the roughest film, while dopants that did not form particles (nickel, osmium) resulted in SnO2 grain size very close to that of pure SnO2 . 相似文献
997.
Coutureau Etienne; Marchand Alain R.; Di Scala Georges 《Canadian Metallurgical Quarterly》2009,123(2):443
The current view of instrumental conditioning indicates that performance in the early stage of training is maintained by a representation of the outcome, as indexed by its sensitivity to changes in the value of the reward. In the present study, the authors tested the effects of a disconnection of the prelimbic cortex (PL) and the basolateral nucleus of the amygdale (BLA), using an asymmetric lesion procedure, to determine whether these structures interact sequentially as part of a corticolimbic system. In marked contrast to the effects of bilateral lesions of the PL or the BLA, which both altered rats' sensitivity to outcome devaluation, the disconnection of these 2 brain areas was without an effect on outcome devaluation. These results demonstrate that the PL and the BLA mediate different aspects of outcome representation in goal-directed responding. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
998.
Hua Yang Yuchao Nie Hongbin Zhang Zengru Di Ying Fan 《Computer Physics Communications》2009,180(9):1511-748
The express delivery industry is developing rapidly in recent years and has attracted attention in many fields. Express shipment service requires that parcels be delivered in a limited time with a low operation cost, which requests a high level and efficient express transport network (ETN). The ETN is constructed based on the public transport networks, especially the airline network. It is similar to the airline network in some aspects, while it has its own feature. With the complex network theory, the topological properties of the ETN are analyzed deeply. We find that the ETN has the small-world property, with disassortative mixing behavior and rich club phenomenon. It also shows difference from the airline network in some features, such as edge density and average shortest path. Analysis on the corresponding distance-weighted network shows that the distance distribution displays a truncated power-law behavior. At last, an evolving model, which takes both geographical constraint and preference attachment into account, is proposed. The model shows similar properties with the empirical results. 相似文献
999.
1000.