全文获取类型
收费全文 | 634篇 |
免费 | 42篇 |
专业分类
电工技术 | 30篇 |
化学工业 | 149篇 |
金属工艺 | 4篇 |
机械仪表 | 22篇 |
建筑科学 | 28篇 |
能源动力 | 41篇 |
轻工业 | 31篇 |
水利工程 | 3篇 |
无线电 | 37篇 |
一般工业技术 | 112篇 |
冶金工业 | 109篇 |
原子能技术 | 2篇 |
自动化技术 | 108篇 |
出版年
2023年 | 9篇 |
2022年 | 6篇 |
2021年 | 28篇 |
2020年 | 14篇 |
2019年 | 14篇 |
2018年 | 13篇 |
2017年 | 18篇 |
2016年 | 28篇 |
2015年 | 23篇 |
2014年 | 29篇 |
2013年 | 61篇 |
2012年 | 50篇 |
2011年 | 36篇 |
2010年 | 22篇 |
2009年 | 40篇 |
2008年 | 26篇 |
2007年 | 24篇 |
2006年 | 23篇 |
2005年 | 11篇 |
2004年 | 16篇 |
2003年 | 12篇 |
2002年 | 9篇 |
2001年 | 10篇 |
2000年 | 8篇 |
1999年 | 5篇 |
1998年 | 34篇 |
1997年 | 35篇 |
1996年 | 22篇 |
1995年 | 4篇 |
1994年 | 3篇 |
1993年 | 5篇 |
1992年 | 2篇 |
1990年 | 2篇 |
1989年 | 3篇 |
1988年 | 4篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 5篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1979年 | 3篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 4篇 |
1974年 | 1篇 |
1972年 | 2篇 |
排序方式: 共有676条查询结果,搜索用时 15 毫秒
1.
Casalaro Giuseppina Lucia Cattivera Giulio Ciccozzi Federico Malavolta Ivano Wortmann Andreas Pelliccione Patrizio 《Software and Systems Modeling》2022,21(1):19-49
Software and Systems Modeling - Mobile robots operate in various environments (e.g. aquatic, aerial, or terrestrial), they come in many diverse shapes and they are increasingly becoming parts of... 相似文献
2.
3.
4.
Dr. Maria L. Di Paolo Dr. Michael S. Christodoulou Dr. Alessandra M. Calogero Dr. Luca Pinzi Prof. Giulio Rastelli Prof. Daniele Passarella Prof. Graziella Cappelletti Prof. Lisa Dalla Via 《ChemMedChem》2019,14(18):1641-1652
A series of 2-phenyloxazoles bearing an amide group at position 4 were designed and synthesized for evaluation as potential inhibitors of human recombinant monoamine oxidases (hrMAOs). Results of kinetics experiments demonstrated that all compounds behave as competitive MAO inhibitors, with good selectivity toward the MAO-B isoform. The most potent and selective derivatives are characterized by inhibition constant (Ki) values in the sub-micromolar range and a good selectivity index (Ki MAO-A/Ki MAO-B>50). Some derivatives were also found to be able to inhibit MAO activity in nerve growth factor (NGF)-differentiated PC12 cells, taken as a model of neuronal cells. In particular, 2-(2-hydroxyphenyl)-N-phenyloxazole-4-carboxamide (compound 4 a ) may be a promising new scaffold, exerting the highest selectivity and inhibitory effect toward MAOs in NGF-differentiated PC12 cell lysates, without compromising cell viability. Molecular docking analysis allowed a rationalization of the experimentally observed binding affinity and selectivity. 相似文献
5.
Giulio Costa Marco Montemurro Jérôme Pailhès 《International Journal of Mechanics and Materials in Design》2018,14(4):669-696
In this paper, the solid isotropic material with penalisation (SIMP) method for topology optimisation of 2D problems is reformulated in the non-uniform rational BSpline (NURBS) framework. This choice implies several advantages, such as the definition of an implicit filter zone and the possibility for the designer to get a geometric entity at the end of the optimisation process. Therefore, important facilities are provided in CAD postprocessing phases in order to retrieve a consistent and well connected final topology. The effect of the main NURBS parameters (degrees, control points, weights and knot-vector components) on the final optimum topology is investigated. Classic geometric constraints, as the minimum and maximum member size, have been integrated and reformulated according to the NURBS formalism. Furthermore, a new constraint on the local curvature radius has been developed thanks to the NURBS formalism and properties. The effectiveness and the robustness of the proposed method are tested and proven through some benchmarks taken from literature and the results are compared with those provided by the classical SIMP approach. 相似文献
6.
Gloria Ravegnini Bruno Fosso Viola Di Saverio Giulia Sammarini Federica Zanotti Giulio Rossi Monica Ricci Federica DAmico Giorgia Valori Antonella Ioli Silvia Turroni Patrizia Brigidi Patrizia Hrelia Sabrina Angelini 《International journal of molecular sciences》2020,21(24)
Gastric cancer (GC) is the fifth most prevalent cancer worldwide and the third leading cause of global cancer mortality. With the advances of the omic studies, a heterogeneous GC landscape has been revealed, with significant molecular diversity. Given the multifaceted nature of GC, identification of different patient subsets with prognostic and/or predictive outcomes is a key aspect to allow tailoring of specific treatments. Recently, the involvement of the microbiota in gastric carcinogenesis has been described. To deepen this aspect, we compared microbiota composition in signet-ring cell carcinoma (SRCC) and adenocarcinoma (ADC), two distinct GC subtypes. To this purpose, 10 ADC and 10 SRCC and their paired non-tumor (PNT) counterparts were evaluated for microbiota composition through 16S rRNA analysis. Weighted and unweighted UniFrac and Bray–Curtis dissimilarity showed significant community-level separation between ADC and SRCC. Through the LEfSe (linear discriminant analysis coupled with effect size) tool, we identified potential microbial biomarkers associated with GC subtypes. In particular, SRCCs were significantly enriched in the phyla Fusobacteria, Bacteroidetes, Patescibacteria, whereas in the ADC type, Proteobacteria and Acidobacteria phyla were found. Overall, our data add new insights into GC heterogeneity and may contribute to deepening the GC classification. 相似文献
7.
8.
Sensory analysis integrated by palynological and physicochemical determinations plays a key role in differentiating unifloral honeys of similar botanical origins (Myrtaceae honeys from southern Spain) 下载免费PDF全文
Inmaculada Rodríguez Salud Serrano Hortensia Galán‐Soldevilla Giulio Piva Jose Luis Ubera 《International Journal of Food Science & Technology》2015,50(7):1545-1551
Myrtaceae honeys produced in Sierra Morena (southern Spain, Andalusia) are obtained from both Eucalyptus camaldulensis and Myrtus communis, and honeys can be easily confused when classified as they come from the same botanical family. The characterisation was intended on the basis of their physicochemical, sensory and palynological properties. Cluster analysis (CA) and principal component analysis (PCA) allowed us to make a distinction between two honey profiles. The first one corresponds to the European sensory profile described for Eucalyptus unifloral honeys. The second profile, which sensory characteristics are absolutely different, has not been previously described. Classification of samples is proposed to be based on their pollen type and content and sensory attributes. Therefore, pollen type and content in E. camaldulensis and M. communis are required to distinguish Eucalyptus honey type from other honeys coming from Myrtaceae family. Sensory analysis identifies honey botanical source as well as palynological analysis: Eucalyptus sensory profile requires over 50% of E. camaldulensis and under 30% of M. communis pollen. Previously undefined sensory profile of myrtle honey is showed under 50% of E. camaldulensis and over 30% of M. communis pollen. 相似文献
9.
With the aim of validating a new standardized Coaxial Double Ring testing procedure, without overpressure and with fixed geometry, an ad hoc theoretical approach has been proposed here to rearrange the laboratory outcomes accounting for the effects of the geometric non-linearities associated with such a testing configuration. By borrowing this idea, once the experimental values of the failure load have been determined, it has been possible to obtain an expression in closed form (fully defined by only two coefficients) of the maximum tensile stress (σmax) in the core of the specimen. Following this, in order to make the laboratory outcomes comparable and homogeneous, the σmax-values have been then re-scaled to a common reference condition (equibiaxial stress on a reference area, σeqbx), by means of the use of a correction coefficient (K) able to determine, under a condition of equal probability of failure, the effective area (Aeff) of the tested specimens. After being corrected to account for the effects of the stress corrosion cracking (static fatigue effect), all re-scaled data have been finally interpreted using a Weibull-type statistical distribution to determine the main fractile values of the glass strength. Doing so, despite some unavoidable approximations, this procedure furnished a highly effective means of determining the bending strength of float glass. Unlike the pure numerical approach proposed in codes and literature, which requires to correct the experimental data via FEM simulation, the rationale behind the proposed approach is in fact to elaborate the experimental data through an analytic treatment of the problem, which would greatly facilitate the interpretation of the data as well as the standardization of the testing procedure. 相似文献
10.
Spatial agglomeration and productivity in Italy: A panel smooth transition regression approach 下载免费PDF全文
Giulio Cainelli Andrea Fracasso Giuseppe Vittucci Marzetti 《Papers in Regional Science》2015,94(Z1):S39-S67
The paper analyses the nonlinearities in the impact of localization, diversity, urbanization and competition on firm‐level total factor productivity (TFP), using a large sample of Italian firms from 1999 to 2007. We adopt a panel smooth transition regression model, so that the TFP elasticities are free to vary smoothly across two or more extreme values. Results show that localization economies and Jacobian externalities materialize only for values of, respectively, intra‐industry agglomeration and extra‐sectoral diversity above a certain threshold. Local competition exerts a positive effect on productivity, even though the marginal impact shrinks at high levels of competition. We find instead no evidence of diseconomies of agglomeration. 相似文献