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71.
The preliminary results of a project that is currently investigating the nature and range of meanings of Antarctic heritage are explored. The project involves two visits to Scott Base, and the subjects of the qualitative research are the members of the New Zealand Antarctic community. Work so far suggests that different meanings do exist, and a four-fold typology of meanings is suggested which needs to be considered in decisions affecting the future of Antarctica. 相似文献
72.
Renata C.K. Kaminski Sandra H. Pulcinelli Celso V. Santilli Florian Meneau Stéphanie Blanchandin Valérie Briois 《Journal of the European Ceramic Society》2010,30(2):193-198
In this paper an unprecedent thermo-reversible sol–gel transition for titania nanoparticles dispersed in a solution of p-toluene sulfonic acid (PTSH) in isopropanol is reported. The sol formed by the thermo-hydrolysis at 60 °C of titanium tetraisopropoxide (Ti(OiPr)4) reversibly changes into a turbid gel upon cooling to room temperature. Turbidimetric measurements performed for samples containing different nominal acidity ratios (A = [PTSH]/[Ti]) have evidenced that the gel transformation temperature increases from 20 to 35 °C as the [PTSH]/[Ti] ratio increases from 0.2 to 2.0. SAXS results indicate that the thermo-reversible gelation is associated to a reversible aggregation of a monodisperse set of titania nanoparticles with average gyration radius of ≈2 nm. From the different PTSH species evidenced by Raman spectroscopy and TG/DTA of dried gels we proposed that the thermo-reversible gelation in this systems is induced by the formation of a supramolecular network, in which the protonated surface of nanoparticles is interconnected through cooperative hydrogen bonds between –SO3 groups of p-toluene sulfonic acid. 相似文献
73.
Investigating Strategies of an Irrigation Conflict 总被引:2,自引:2,他引:0
The understanding and modeling of human behavior in conflict situations is a challenge that researches investigate by developing,
modifying and applying computational models. This paper aims to analyze how changes in the strategies of the various groups
involved in a water use conflict can influence the decision process. The case study is an irrigation system supplied by a
main canal in Rio de Janeiro State, Southeastern Brazil. Conflicts arise due to hydraulic constraints of the canal, resulting
in water unavailability for some irrigators or damage to potentially irrigable lands caused by adjacent floods. The investigation
strategy has been developed, considering three groups of irrigators. They can be geographically identified over the main canal’s
hydrographical limits. Six different scenarios are considered to analyze the conflict. These scenarios are built taking into
account six different policies of water conveyance. Additionally, the decision of the state government related to water charging
has been considered. The final decision is taken by the management institution of the canal which also has two different tendencies:
to opt for the scenarios providing highest net profits or to be impartial in the final decision. The Graph Model for Conflict
Resolution, which solves non-cooperative games based on graph theory, was adopted to evaluate all these strategies. The results
show that, according to the level of exigency of irrigator groups, state government and management institution, the conflict
can in fact, be resolved. 相似文献
74.
The generalized access network design problem consists of finding a topology, capacity assignment and routing that minimize
the sum of costs to connect every pair of remote unit and its central node specified by the telecommunication company. We
consider an integer programming formulation with a partial multicommodity structure. We analyze some aspects and extensions
of the proposed model and we introduce a heuristic based on Lagrangian relaxation and the subgradient method. We report computational
results for a set of randomly generated test problems. They include networks with up to 300 nodes and show that even problem
instances defined in small networks can be extremely difficult problems. The heuristic generates effective and acceptable
designs from the practical point of view. We compare our heuristic with a commercial code.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
75.
Response of structures to static and dynamic loads may be assessed in terms of energy. The energy evaluation depends on hysteretic models used to describe inelastic behavior of structures and their elements. One of the hysteretic models often employed in structural analysis is the Ramberg–Osgood model. In the paper a physically motivated model, which leads to the Ramberg–Osgood force–displacement relationship under monotonic loading and exhibits Masing type of behavior for unloading/reloading, is described. Based on the model formulas to calculate recoverable elastic strain energy and irrecoverable hysteretic energy for systems/elements under monotonic loading are derived. It is also shown how recoverable elastic strain energy and irrecoverable hysteretic energy can be evaluated at any point of unloading/reloading curves for a system/element of Masing type. The application of the derived formulas is illustrated by evaluating the energy of a single-degree-of-freedom system subjected to impulse and seismic loading. 相似文献
76.
V. Val. Sobolev 《Glass Physics and Chemistry》2002,28(6):399-416
The complete sets of the spectra of optical fundamental functions for vitreous arsenic chalcogenides in the energy range 0–40 eV are compared for the first time. The general features of the spectra and their dependence on the nature of the chalcogen anion are revealed. 相似文献
77.
78.
Dr. Valérie Pezo Guy Schepers Dr. Catia Lambertucci Dr. Philippe Marlière Prof. Piet Herdewijn 《Chembiochem : a European journal of chemical biology》2014,15(15):2255-2258
The templating potential of anhydrohexitol oligonucleotides bearing ambiguous bases was studied in vivo, by using a selection screen for mosaic heteroduplex plasmids in Escherichia coli. 1,5‐Anhydro‐2,3‐dideoxy‐2‐(5‐nitroindazol‐1‐yl)‐D ‐arabino‐hexitol showed the greatest ambiguity among the three nucleosides tested. At most two successive ambiguous bases could be tolerated on hexitol templates read in bacterial cells. Hexitol nucleosides bearing simplified heterocycles thus stand as promising monomers for generating random DNA sequences in vivo from defined synthetic oligonucleotides. 相似文献
79.
Piccand V Meier S Cutullic E Weilenmann S Thomet P Schori F Burke CR Weiss D Roche JR Kunz PL 《The Journal of dairy research》2011,78(4):464-470
The objectives of the study were to compare the ovarian activity of Holstein-Friesian (CH HF), Fleckvieh (CH FV) and Brown Swiss (CH BS) dairy cows of Swiss origin with that of Holstein-Friesian (NZ HF) dairy cows of New Zealand origin, the latter being used as a reference for reproductive performance in pasture-based seasonal calving systems. Fifty, second-lactation NZ HF cows were each paired with a second-lactation Swiss cow (17, 15 and 18 CH HF, CH FV and CH BS respectively) in 13 pasture-based, seasonal-calving commercial dairy farms in Switzerland. Ovarian activity was monitored by progesterone profiling from calving to first breeding service. CH BS cows produced less energy-corrected milk (mean 22·8 kg/d) than the other breeds (26·0-26·5 kg/d) during the first 100 d of lactation. CH HF cows had the lowest body condition score (BCS) at calving and the greatest BCS loss from calving to 30 d post partum. Commencement of luteal activity (CLA) was later for NZ HF than for CH FV (51·5 v. 29·2 d; P <0·01), with CH HF and CH BS intermediate (43 d). On average, NZ HF and CH HF cows had one oestrous cycle before the onset of the seasonal breeding period; this was less (P<0·01) than either CH FV (1·7) or CH BS (1·6). There was a low prevalence of luteal persistency (3%) among the studied cows. First and second oestrous cycle inter-ovulatory intervals did not differ between breeds (20·5-22·6 d). The luteal phase length of CH BS during the second cycle was shorter (10·6 d) than that of the other breeds (13·8-16·0 d), but the inter-luteal interval was longer (9·8 d v. 7·0-8·0 d). The results suggest that the Swiss breeds investigated have a shorter interval from calving to CLA than NZ HF cows. 相似文献
80.
Alabdeh M Lechevalier V Nau F Gautier M Cochet MF Gonnet F Jan S Baron F 《Journal of food protection》2011,74(1):24-31
The mechanism of egg white antimicrobial activity involves specific molecules and environmental factors. However, it is difficult to compare the data from the literature because of the use of various bacterial strains and incubation conditions. The aim of our study was to determine the effect of temperature, pH, inoculum size, and egg white protein concentration on egg white antimicrobial activity and to investigate the putative interactions among these factors by conducting a complete factorial design analysis. The behavior of Salmonella Enteritidis and Escherichia coli was studied after precultivation in tryptic soy broth and Luria-Bertani broth, respectively, using three different egg white protein concentrations (0, 10, and 100%), five temperatures (37, 40, 42, 45, and 48°C), two pHs (7.8 and 9.3), and six inoculum levels (3 to 8 log CFU/ml). The essential role of temperature was identified. An inverse relationship was observed between bacterial growth and an increase in temperature. The role of egg white proteins was clearly demonstrated. In the absence of egg white proteins, bacterial growth occurred under most incubation conditions, whereas the presence of 10 and 100% protein produced bacteriostatic or bactericidal effects. The interaction between temperature and protein concentration was significant. At the highest tested temperatures, proteins were less involved in the bactericidal effect. Bacterial destruction was higher at pH 9.3 than at pH 7.8. Under our experimental conditions, Salmonella Enteritidis was more resistant to inactivation by egg white than was E. coli. 相似文献