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排序方式: 共有832条查询结果,搜索用时 15 毫秒
61.
Juliana Vinholes Clara Grosso Paula B. Andrade Angel Gil-Izquierdo Patrícia Valentão Paula Guedes de Pinho Federico Ferreres 《Food chemistry》2011
Spergularia rubra is distributed all over the world, being its infusion used as diuretic. In spite of its large use, the antidiabetic, anti-cholinesterase and antioxidant activities of this species have not been assessed and its chemical composition is scarcely known. In the work herein a hydromethanolic extract was studied. 相似文献
62.
Pablo Sevilla Clara Sandino Milena Arciniegas Jordi Martínez-Gomis Maria Peraire Francisco Javier Gil 《Materials science & engineering. C, Materials for biological applications》2010,30(1):14-19
Lately new biomedical grade yttria stabilized zirconia (YTZP) dental implants have appeared in the implantology market. This material has better aesthetical properties than conventional titanium used for implants but long term behaviour of these new implants is not yet well known. The aim of this paper is to quantify the mechanical response of YTZP dental implants previously degraded under different time conditions and compare the toughness and fatigue strength with titanium implants. Mechanical response has been studied by means of mechanical testing following the ISO 14801 for Standards for dental implants and by finite element analysis. Accelerated hydrothermal degradation has been achieved by means of water vapour and studied by X-ray diffraction and nanoindentation tests. The results show that the degradation suffered by YTZP dental implants will not have a significant effect on the mechanical behaviour. Otherwise the fracture toughness of YTZP ceramics is still insufficient in certain implantation conditions. 相似文献
63.
Mónica Martins Sandra Chaves Maria Clara Costa 《The Science of the total environment》2010,408(12):2621-2628
This work was conducted to assess the impact of uranium (VI) on sulphate-reducing bacteria (SRB) communities obtained from environmental samples collected on the Portuguese uranium mining area of Urgeiriça. Culture U was obtained from a sediment, while culture W was obtained from sludge from the wetland of that mine. Temperature gradient gel electrophoresis (TGGE) was used to monitor community changes under uranium stress conditions. TGGE profiles of dsrB gene fragment demonstrated that the initial cultures were composed of SRB species affiliated with Desulfovibrio desulfuricans, Desulfovibrio vulgaris and Desulfomicrobium spp. (sample U), and by species related to D. desulfuricans (sample W). A drastic change in SRB communities was observed as a result of uranium (VI) exposure. Surprisingly, SRB were not detected in the uranium removal communities. Such findings emphasize the need of monitoring the dominant populations during bio-removal studies. TGGE and phylogenetic analysis of the 16S rRNA gene fragment revealed that the uranium removal consortia are composed by strains affiliated to Clostridium genus, Caulobacteraceae and Rhodocyclaceae families. Therefore, these communities can be attractive candidates for environmental biotechnological applications associated to uranium removal. 相似文献
64.
Emissions of perfluorinated alkylated substances (PFAS) from point sources--identification of relevant branches 总被引:3,自引:0,他引:3
Effluents of wastewater treatment plants are relevant point sources for the emission of hazardous xenobiotic substances to the aquatic environment. One group of substances, which recently entered scientific and political discussions, is the group of the perfluorinated alkylated substances (PFAS). The most studied compounds from this group are perfluorooctanoic acid (PFOA) and perfluorooctane sulphonate (PFOS), which are the most important degradation products of PFAS. These two substances are known to be persistent, bioaccumulative and toxic (PBT). In the present study, eleven PFAS were investigated in effluents of municipal wastewater treatment plants (WWTP) and in industrial wastewaters. PFOS and PFOA proved to be the dominant compounds in all sampled wastewaters. Concentrations of up to 340 ng/L of PFOS and up to 220 ng/L of PFOA were observed. Besides these two compounds, perfluorohexanoic acid (PFHxA) was also present in nearly all effluents and maximum concentrations of up to 280 ng/L were measured. Only N-ethylperfluorooctane sulphonamide (N-EtPFOSA) and its degradation/metabolisation product perfluorooctane sulphonamide (PFOSA) were either detected below the limit of quantification or were not even detected at all. Beside the effluents of the municipal WWTPs, nine industrial wastewaters from six different industrial branches were also investigated. Significantly, the highest emissions or PFOS were observed from metal industry whereas paper industry showed the highest PFOA emission. Several PFAS, especially perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), perfluorododecanoic acid (PFDoA) and PFOS are predominantly emitted from industrial sources, with concentrations being a factor of 10 higher than those observed in the municipal WWTP effluents. Perfluorodecane sulphonate (PFDS), N-Et-PFOSA and PFOSA were not detected in any of the sampled industrial point sources. 相似文献
65.
Examined the results of experiments where Ss were required to detect the misalignment of 2 abutting dot clusters on a monitor screen. Thresholds varied with the square root of dot density and did not appear to be affected by changing the sampling strategy used to generate the random dot clusters. Comparison of the Ss' performance with that expected of 3 information processing strategies suggested that Ss accomplished the task by locating the edges of the dot clusters rather than by extracting measures of global scope or of central position. The efficiency with which edge information was extracted was approximately 50% for low-density stimuli and declined exponentially with increasing dot density. (French abstract) (18 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
66.
Rochlen Aaron B.; Ligiero Daniela P.; Hill Clara E.; Heaton Kristin J. 《Canadian Metallurgical Quarterly》1999,46(1):27
Forty-two volunteer clients with below-average dream recall and attitudes toward dreams participated in training sessions focusing on either improving dream recall and attitudes toward dreams, building dream interpretation skills, or educating about counseling. After training, individual dream interpretation sessions were conducted. No significant differences were found among the 3 conditions in regard to dream recall, attitudes toward dreams, or client- or therapist-reported session outcome, but effect sizes suggested that participants in the skills condition gained more from sessions than did participants in the dream recall–attitudes condition. Session outcome for all volunteer clients was equivalent to those in previous studies of volunteer clients with no training, suggesting that training was not necessary and that these participants were able to benefit from single-session dream interpretation. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
67.
Journal of the American Oil Chemists' Society - 相似文献
68.
69.
Anna Clara Monti 《时间序列分析杂志》1998,19(2):209-219
A method is proposed for the preliminary estimation of the parameters of multivariate moving-average processes. Initially, m independent white-noise series are generated. Then the parameters are estimated through an iterative procedure. The algorithm is fast and simple since it does not require specialized software for time series but a least squares routine. The estimators are consistent and a simulation experiment shows good performance in finite samples. An applicati on to real data is also illustrated 相似文献
70.
Volatile compounds were isolated from copoazú (Theobroma grandiflorum Schumann) fruit by liquid–liquid extraction at two different pH values of 3.3 (natural) and 7. The volatile extracts were analyzed by capillary GC–FID and GC–MS. Among the 56 compounds identified at two pH values, many of them were only present in the lower pH extract, confirming the presence of bound compounds in copoazú. Ethyl butanoate, ethyl hexanoate and linalool were the major constituents found in copoazú fruit. 相似文献