全文获取类型
收费全文 | 248篇 |
免费 | 9篇 |
国内免费 | 1篇 |
专业分类
化学 | 149篇 |
晶体学 | 5篇 |
力学 | 7篇 |
数学 | 22篇 |
物理学 | 75篇 |
出版年
2024年 | 3篇 |
2023年 | 4篇 |
2022年 | 15篇 |
2021年 | 18篇 |
2020年 | 19篇 |
2019年 | 17篇 |
2018年 | 16篇 |
2017年 | 11篇 |
2016年 | 20篇 |
2015年 | 9篇 |
2014年 | 7篇 |
2013年 | 18篇 |
2012年 | 17篇 |
2011年 | 14篇 |
2010年 | 8篇 |
2009年 | 8篇 |
2008年 | 2篇 |
2007年 | 3篇 |
2006年 | 7篇 |
2005年 | 9篇 |
2004年 | 4篇 |
2003年 | 3篇 |
2002年 | 4篇 |
2000年 | 4篇 |
1999年 | 2篇 |
1998年 | 3篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1987年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1941年 | 2篇 |
排序方式: 共有258条查询结果,搜索用时 171 毫秒
251.
Ceyla Yorucu Katherine Lau Shweta Mittar Nicola H. Green Ahtasham Raza Ihtesham Ur Rehman 《应用光谱学评论》2016,51(4):263-277
Invasion of melanoma cells from the primary tumor involves interaction with adjacent tissues and extracellular matrix. The extent of this interaction is not fully understood. In this study Raman spectroscopy was applied to cryo-sections of established 3D models of melanoma in human skin. Principal component analysis was used to investigate differences between the tumor and normal tissue and between the peri-tumor area and the normal skin. Two human melanoma cells lines A375SM and C8161 were investigated and compared in 3D melanoma models. Changes were found in protein conformations and tryptophan configurations across the entire melanoma samples, in tyrosine orientation and in more fluid lipid packing only in tumor dense areas, and in increased glycogen content in the peri-tumor areas of melanoma. Raman spectroscopy revealed changes around the perimeter of a melanoma tumor as well as detecting differences between the tumor and the normal tissue. 相似文献
252.
In this paper, the Laguerre–Sheffer polynomials are introduced by using the monomiality principle formalism and operational methods. The generating function for the Laguerre–Sheffer polynomials is derived and a correspondence between these polynomials and the Sheffer polynomials is established. Further, differential equation, recurrence relations and other properties for the Laguerre–Sheffer polynomials are established. Some concluding remarks are also given. 相似文献
253.
Shaikh SR Cherezov V Caffrey M Soni SP LoCascio D Stillwell W Wassall SR 《Journal of the American Chemical Society》2006,128(16):5375-5383
The major mammalian plasma membrane lipids are phosphatidylcholines (PCs), phosphatidylethanolamines (PEs), and cholesterol. Whereas PC-cholesterol interactions are well studied, far less is known about those between PE and cholesterol. Here, we investigated the molecular organization of cholesterol in PEs that vary in their degree of acyl chain unsaturation. For heteroacid sn-1 saturated (palmitoyl), sn-2 unsaturated (various acyl chain) PEs, cholesterol solubility determined by X-ray diffraction was essentially identical with 1 (oleoyl, 51 +/- 3 mol %) and 2 (linoleoyl, 49 +/- 2 mol %) double bonds before decreasing progressively with 4 (arachidonyl, 41 +/- 3 mol %) and 6 (docosahexaenoyl, 31 +/- 3 mol %) double bonds. With 6 double bonds in each chain, cholesterol solubility was further reduced to 8.5 +/- 1 mol %. However, (2)H NMR experiments established that the orientation of cholesterol in the same heteroacid PE membranes was unaffected by the degree of acyl chain unsaturation. A tilt angle of 15 +/- 1 degrees was measured when equimolar [3alpha-(2)H(1)]cholesterol was added, regardless of the number of double bonds in the sn-2 chain. The finding that solubility of cholesterol in sn-1 saturated PEs depends on the amount of polyunsaturation in the sn-2 chain of PE differs from the equivalent PCs that universally incorporate approximately 50 mol % sterol. Unlike PCs, a differential in affinity for cholesterol and tendency to drive lateral segregation is inferred between polyunsaturated PEs. This distinction may have biological implications reflected by the health benefits of dietary polyunsaturated fatty acids that are often taken up into PE > PC. 相似文献
254.
Toscano G Raza S Xiao S Wubs M Jauho AP Bozhevolnyi SI Mortensen NA 《Optics letters》2012,37(13):2538-2540
Giant field enhancement and field singularities are a natural consequence of the commonly employed local-response framework. We show that a more general nonlocal treatment of the plasmonic response leads to new and possibly fundamental limitations on field enhancement with important consequences for our understanding of surface-enhanced Raman spectroscopy (SERS). The intrinsic length scale of the electron gas serves to smear out assumed field singularities, leaving the SERS enhancement factor finite, even for geometries with infinitely sharp features. For silver nanogroove structures, mimicked by periodic arrays of half-cylinders (up to 120 nm in radius), we find no enhancement factors exceeding 10 orders of magnitude (10(10)). 相似文献
255.
Mubasher?JamilEmail author D.?Momeni Muhammad?Raza Ratbay?Myrzakulov 《The European Physical Journal C - Particles and Fields》2012,72(4):1999
In this paper, we reconstruct cosmological models in the framework of f(R,T) gravity, where R is the Ricci scalar and T is the trace of the stress-energy tensor. We show that the dust fluid reproduces ΛCDM, phantom–non-phantom era and phantom cosmology. Further, we reconstruct different cosmological models, including the Chaplygin
gas, and scalar field with some specific forms of f(R,T). Our numerical simulation for the Hubble parameter shows good agreement with the BAO observational data for low redshifts,
z<2. 相似文献
256.
Aiza Azam Gulzar Muhammad Muhammad Shahbaz Aslam Muhammad Mudassir Iqbal Muhammad Arshad Raza Naeem Akhtar Muhammad Ajaz Hussain Noreen Sajjad Asad Syed Ali H. Bahkali Zahid Shafiq 《应用有机金属化学》2023,37(1):e6923
The multifunctional zinc oxide nanoparticles are synthesized using a cost-effective, efficient, eco-friendly, simple, and clean synthesis approach. Herein, we reported the antibacterial and wound healing potential of zinc oxide nanoparticles (ZnO-NPs) prepared using psyllium gel (PG) as the reducing and stabilizing agent. The PG-mediated zinc oxide nanoparticles (PG-ZnO-NPs) were characterized using UV–Vis, photoluminescence (PL), FTIR, XRD, Raman, and SEM. UV–Vis spectral studies confirmed the surface plasmonic resonance (SPR) band at 364 nm. PL results demonstrated the fluorescent or emission nature of PG-ZnO-NPs. FTIR analysis confirmed characteristic peaks at 873.82 and 619.88 cm−1 due to the tetrahedral coordination of zinc and the formation of the Zn-O bond. XRD and Raman confirm the formation of PG-ZnO-NPs, whereas SEM analysis revealed PG-ZnO-NPs are rod-shaped, having hexagonal prism-like bases, and EDX exhibited the elemental composition of PG-ZnO-NPs. The as-synthesized PG-ZnO-NPs possessed prominent microbicidal potential against gram-positive (Bacillus subtilis and Bacillus licheniformis) and gram-negative (Escherichia coli and Salmonella shigella) bacterial strains in terms of zone of inhibition (ZOI), minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC). In vivo biological investigations with mice show that the synthesized PG-ZnO-NPs possess outstanding biocompatibility and wound healing potential. PG-ZnO-NPs dressing significantly speeds up full-thickness wound repair by triggering a decrease in MMP-1 and MMP-2 and escalating the mRNA levels of collagen types (I & III) and fibronectin. Thus, our work validates that the inclusion of PG-ZnO-NPs in dressing shows excellent potential for acute wound management. 相似文献
257.
Rabeeah Raza Rahila Naz Sara I. Abdelsalam 《Numerical Methods for Partial Differential Equations》2023,39(2):975-994
In the present article, radiative Sutterby nanofluid flow over a stretchable cylinder is considered. The suspended swimming microorganisms have been deliberated in the fluid analysis. Different processes such as Brownian motion, thermophoresis, Joules heating, and viscous dissipation have been inspected in the presences of stratification parameters. The solutions for flow profiles have been obtained via optimal homotopy analysis method. Impacts of different physical involved variables on non-dimensional velocity, temperature, nanofluid concentration, and concentration of density of swimming microorganisms have been debated. Coefficient of skin friction, local Nusselt number, Sherwood number, and density of motile organisms have been calculated. The results reveal that Sutterby fluid parameter enhances the skin friction and has a reverse impact on the velocity, while an increase in stratification causes a declination in the flow boundary layers. The temperature of the flow is also seen to be boosted by the increment in Brownian motion parameter. Analysis of entropy generation shows that the concentration difference parameter maximizes the entropy and minimizes the dimensionless Bejan number. 相似文献
258.