Search

IntroductionGeneric substitution is encouraged to reduce pharmaceutical spending in China, and with incentive policies, the market size of the generic drug continues to rise. To find out how the generic competition affects drug price in this area, this study examines how the quantity of generic drug manufacturers can influence average drug price in the Chinese market.MethodsThis study uses a rigorous selection of drugs from the 2021 China’s National Reimbursement Drug List (NRDL), and uses drug-level fixed effects regressions to estimate the relationship between competition and price within each drug.ResultsWe note that drug prices decline with increasing competition in the Chinese market, but not in a perfectly linear manner, with marginal price declines decreasing after the fourth entrant and “rebounding” at subsequent entrants, especially the sixth.DiscussionThe findings suggest the importance of maintaining effective competition between suppliers to control prices, and that the government needs to further control generic pricing, especially for late entry generics, to ensure effective competition in the Chinese market.

In order to study the drawing interface mechanical properties of threaded steel bolt and the drawing failure process of anchor structure, on the basis of bolt tensile test and numerical simulation, the symmetrical plane model of threaded steel bolt anchorage is established by using finite element software ABAQUS. Based on the interface bond damage model, the whole process of drawing failure of threaded steel bolt is numerically simulated. The results show that: the numerical simulation can restore the tensile fracture process of the real bolt. Different from the tensile fracture characteristics of round steel, the tensile fracture orientation of the bolt is parallel to the inclination angle of the rib; the variation law of load displacement curves of bolts with different rib spacings show that the smaller the rib spacing of bolts, the better the anchorage bearing performance, and the existence of bolt transverse rib can not only improve the bonding contact area, but also increase the mechanical biting force; with the increase of the pull-out load, the rock mass gradually fails from the front end to the back end in a funnel-like manner, and the interface damage and shear stress peak gradually move to the deep part of the anchorage. The damage of bolt, rock mass or interface will cause the fluctuation of load-displacement curve of bolt. The more severe the damage is, the more obvious the fluctuation of load displacement curve is.

Species richness, body size, and range size are among key subjects in animal macroecology and biogeography. To date, the species richness–body size–range size nexus remains largely understudied at a global scale and for large taxonomic groups. Here we examine the relative role of species richness and body size in determining species range size among terrestrial vertebrates across spatial and taxonomic scales. We then test related hypotheses in the context of Rapoport’s rule, latitude, and climate variation. To do this, we used simultaneous autoregressive analysis and structural equation modeling to test for statistical relationships among species richness, body size, and range size for all terrestrial vertebrates and for each continent. We then investigated the relative contributions of richness, body size, latitude, climate variation, and their combinations in the variations in species range sizes. We found that species richness consistently shows strong negative correlations with range size at global, regional, and within-region levels, and for all terrestrial vertebrates, and for each of the four classes (i.e., birds, mammals, amphibians, and reptiles). The strength of the relationships increased with richness and with spatial and taxonomic scales. Globally, species richness explained more variation in species range size than did latitude and climates. Body size contributed significantly to the range sizes of all four classes but especially reptiles and amphibians. However, the relative contributions of these factors varied substantially among the continents and terrestrial vertebrate classes. Comparison with the findings of a previous study shows that there were also significant differences in regional patterns between terrestrial vertebrates and plants and the relative contributions of diversity vs. latitude. Our findings show clear relationships among species richness, body size, and range size, but the strength of the relationships varies among regions and taxonomic groups. In general, species richness could predict species range size better than body size, latitude, and climate. These results have important theoretical and applied implications.

Micro-arc oxidation was applied to AZ91D magnesium alloy by taking K2Cr2O7 as the colouring salt in the silicate system. It was shown that the green coating obtained through performing micro-arc oxidation on magnesium alloy consisted of Mg, Mg2SiO4, MgO, and MgCr2O4 based on analysis of X-ray diffraction (XRD), and scanning electron microscopy (SEM). Among which, MgCr2O4 was the colouring salt; there were something in the lamellar, pit, and convex forms found on the surface of the coating. The coating consisted of a porous, and a compact, layer from the outside to the inside. As demonstrated, the colour of the coating depended on the K2Cr2O7 concentration: it became gradually deeper with the addition of K2Cr2O7 and the increasing micro-arc oxidation time. The corrosion resistance and hardness of the green coating were greater than that of the matrix.

The frost resistance and abrasion resistance of the fiber mesh reinforced concrete under the simulated treatment of external environment were studied through the frost resistance test and abrasion test. The relative dynamic modulus, the amount of spalling per unit area, the amount of abrasion per unit area and abrasion depth were used as evaluation indexes. The result shows that the frost resistance and abrasion resistance of concrete can be enhanced by fiber mesh. For the frost resistance, enhancement effect of carbon fiber mesh is better than that of basalt fiber mesh, and better than that of aramid fiber mesh. For the abrasion resistance, enhancement effect of aramid fiber mesh is better than that of basalt fiber mesh, and better than that of carbon fiber mesh. On the whole, the frost resistance and abrasion resistance of basalt fiber mesh reinforced concrete are better. Therefore, basalt fiber mesh is recommended to strengthen the frost resistance and abrasion resistance of concrete in engineering practice.