全文获取类型
收费全文 | 1666篇 |
免费 | 44篇 |
国内免费 | 83篇 |
专业分类
化学 | 1139篇 |
晶体学 | 24篇 |
力学 | 47篇 |
数学 | 2篇 |
物理学 | 581篇 |
出版年
2023年 | 102篇 |
2022年 | 43篇 |
2021年 | 44篇 |
2020年 | 51篇 |
2019年 | 34篇 |
2018年 | 42篇 |
2017年 | 52篇 |
2016年 | 58篇 |
2015年 | 54篇 |
2014年 | 74篇 |
2013年 | 91篇 |
2012年 | 84篇 |
2011年 | 152篇 |
2010年 | 111篇 |
2009年 | 211篇 |
2008年 | 146篇 |
2007年 | 127篇 |
2006年 | 102篇 |
2005年 | 53篇 |
2004年 | 52篇 |
2003年 | 30篇 |
2002年 | 17篇 |
2001年 | 13篇 |
2000年 | 16篇 |
1999年 | 11篇 |
1998年 | 6篇 |
1997年 | 3篇 |
1996年 | 1篇 |
1995年 | 4篇 |
1994年 | 1篇 |
1993年 | 3篇 |
1991年 | 1篇 |
1990年 | 3篇 |
1989年 | 1篇 |
排序方式: 共有1793条查询结果,搜索用时 15 毫秒
71.
Atomic surface structures of nanoparticles are of interest in catalysis and other fields. Aberration-corrected HREM facilitates direct imaging of the surfaces of nanoparticles. A remaining concern of surface imaging arises from beam damage. It is important to identify the intrinsic surface structures and the ones created by electron beam irradiation in TEM. In this study, we performed aberration-corrected HREM and EELS to demonstrate that TiO and bcc type Ti islands form due to intense electron irradiation. The formation of Ti-rich islands is in agreement with previous high temperature annealing experiments on the surfaces of SrTiO3 single crystals. 相似文献
72.
《Journal of Saudi Chemical Society》2020,24(2):282-287
By using urea linked porous organic polymers as template, a new nano palladium catalyst with low Pd loading can be easily prepared (1.0 wt% Pd only). Although such less amount of Pd was contained in this new catalyst, it is still an effective catalyst for the Suzuki-Miyaura coupling of aryl iodines and aryl boric acids, affording biphenyl products in excellent yields with outstandingly enhanced turnover numbers (up to 10,536) under green solvent (water). 相似文献
73.
《中国化学快报》2020,31(12):3168-3172
The copper(II) diethyldithiocarbamate (Cu(DDC)2) complex exhibited excellent inhibition to cancer cells. The usual administration is intravenous injection for disulfram and oral for copper. A new strategy was reported to improve the administration efficiency of the Cu(DDC)2 drug. Poly(lactide-co-glycolide) (PLGA) nanoparticles were used to trap disulfram and copper gluconate separately, the two types of drug loaded nanoparticles were injected in mesothelioma-bearing nude mice via intraperitoneal injection. The in vivo formation of Cu(DDC)2 complex was induced by disulfiram and Cu2+ released from PLGA nanoparticles. This strategy avoided many obstacles in the use of Cu(DDC)2 complex as chemotherapeutic and exhibited excellent anticancer activity to mesothelioma. 相似文献
74.
《Arabian Journal of Chemistry》2020,13(1):916-931
Green and ecofriendly route for biosynthesis of lead oxide nanoparticles has been successfully demonstrated using aqueous leaf extracts of Sageretia thea (Osbeck.). Biosynthesized PbO (∼27 nm) nanoparticles were extensively characterized using XRD, FTIR, Raman, EDS etc. Morphology was studied through HR-TEM/SEM. As synthesized nanoparticles were investigated for their iv-vitro biological properties. Antibacterial activities revealed enhancement upon modulation by UV in a concentration dependent manner. Pseudomonas aeruginosa was found to be the most resistant strain (MIC = 250 µg/mL and MICuv = 31.25 µg/ml). MTT cytotoxicity on leishmania promastigotes and amastigotes revealed significant inhibition as indicated by their IC50 values of 14.7 µg/mL and 11.95 µg/m respectively. Cytotoxicity was also confirmed using brine shrimp lethality (IC50 = 27.7 µg/mL). Bio-compatibility evaluation indicated cytotoxicity to freshly isolated human macrophages (IC50 = 57.1 µg/mL). Insignificant alpha-amylase inhibition and moderate protein kinase inhibition was revealed. Antioxidant activities indicated free radical scavenging activity (58 ± 2.45) at 200 µg/mL. Moderate total reducing power and total antioxidant activity was also indicated. Overall, we conclude lead oxide as a potential candidate for biological applications, however further studies are recommended on their in vitro and in vivo cytotoxicity. 相似文献
75.
《Arabian Journal of Chemistry》2020,13(1):606-619
Cobalt oxide nanoparticles were successfully biosynthesized by complete green process using aqueous leaf extracts of Sageretia thea as chelating agent. Diverse techniques were applied for characterization. Antibacterial (with and without UV illumination), antileishmanial, antioxidant and enzyme inhibition applications were assessed, while freshly isolated macrophages and red blood cells were used for biocompatibility studies. Good antibacterial nature and enhancement of bactericidal nature upon UV modulation is reported. Staphylococcus aureus and Escherichia coli are indicated as most susceptible bacterial strains. Significant cytotoxic potential is revealed with IC50 calculated as 12.82 µg/ml and 3.16 µg/ml against the axenic leishmanial promastigote and amastigote cultures respectively. Biogenic cobalt oxide nanoparticles indicated DPPH free radical scavenging potential, while moderate antioxidant capacity and reducing power was demonstrated. Bioinspired cobalt oxide also demonstrated alpha amylase and protein kinase inhibition at higher concentrations. Biogenic cobalt oxide was found as more cytotoxic to macrophages (IC50 = 58.55 µg/ml) then to RBC’s (IC50 >200 µg/ml). Our results indicate green synthesis as an alternative, effective and eco-friendly method for the biosynthesis of cobalt oxide nanoparticles with numerous biological applications. 相似文献
76.
《Arabian Journal of Chemistry》2020,13(11):7598-7608
Zirconia ceramics have attained much consideration owing to the amazing mechanical strength and white color. These properties provide an opportunity for the use in biomedical applications. In the present study, an application oriented sol-gel route was adapted for synthesis of zirconia nanoparticles. ZrOCl2·8H2O was used as a precursor, iron oxide (Fe3O4) nanoparticles (pH 2 & pH 9) as a stabilizer and de-ionized water was used as a solvent. Sol-gel synthesized iron oxide stabilized zirconia nanoparticles were prepared by varying concentrations of iron oxide nanoparticles in the range of 2–10 wt%. X-ray diffraction results showed mixed phases at all wt% with acidic pH value, while pure tetragonal phase of zirconia was observed for stabilization with 6 wt% basic iron oxide. Maximum value of dielectric constant (~80 at log f = 4) and minimum value of tangent loss (~0.66 at log f = 4) were observed for zirconia stabilized with basic 6 wt% iron oxide. Maximum value of hardness (1410 ± 10 HV) along with high fracture toughness were observed with optimized stabilization. Very weak hemolytic activity and maximum scavenging (~76) antioxidant activity was observed under optimized conditions. Thus, it can be suggested that optimized nanoparticles, i.e. tetragonal zirconia stabilized with 6 wt% of basic Fe3O4, can be further useful for therapeutical and pharmaceutical applications. 相似文献
77.
Dr. Baoyan Xing Dr. Sai Ge Prof. Jianguo Zhao Dr. Hui Yang Dr. Jie Song Dr. Yu Geng Dr. Yuying Qiao Prof. Ling Gu Prof. Peide Han Prof. Guibin Ma 《ChemistryOpen》2020,9(10):1018-1026
Solid-state NMR analysis on wurtzite alloyed CdSe1−xSx crystalline nanoparticles and nanobelts provides evidence that the 113Cd NMR chemical shift is not affected by the varying sizes of nanoparticles, but is sensitive to the S/Se anion molar ratios. A linear correlation is observed between 113Cd NMR chemical shifts and the sulfur component for the alloyed CdSe1−xSx (0<x<1) system both in nanoparticles and nanobelts (δCd=169.71⋅XS+529.21). Based on this correlation, a rapid and applied approach has been developed to determine the composition of the alloyed nanoscalar materials utilizing 113Cd NMR spectroscopy. The observed results from this system confirm that one can use 113Cd NMR spectroscopy not only to determine the composition but also the phase separation of nanomaterial semiconductors without destruction of the sample structures. In addition, some observed correlations are discussed in detail. 相似文献
78.
Effective solid-phase microextraction (SPME) in environmental field represents a crucial step for the adequate extraction of several analytes. Several materials have been traditionally developed for SPME of several analytes from environmental samples, even though their several restrictions such as post-treatment required, elevate costs and limited efficiency. Recently, nanomaterials (NMs) have emerged as a promising substitute for SPME in environmental applications of traditional techniques, due to their small size and their high specific surface-area which enhances their high reactivity. In this present review different NMs which have recently been utilized as SPME sorbent for environmental applications are classified into eleven main groups, namely nanoparticles, nanofibers, nanoflakes, nanocomposites, nanorods, nanotubes, nanohorns, nanosheets, nanocubes, nanospheres and polymer-based NMs. Application of these NMs in SPME modes and configurations for environmental analysis has been reviewed. The study discusses not only the advantages but also the major limitations of using such NMs. 相似文献
79.
The synchronization of diagnosis and treatment is a new trend in cancer treatment. Photoacoustic imaging (PAI) and photothermal therapy (PTT) are recognized as one of the perfect combinations. The autocatalytic polymerization of selenium/polypyrrole (Se@PPy) nanocomposites with a wide-absorption band at near-infrared region (NIR, 800 nm) has been developed in this paper. The wide optical absorption characteristics enable Se@PPy nanocomposites to achieve multi-spectral PAI. Ex vivo experiments show desirable photoacoustic ability of the Se@PPy nanocomposites at wavelengths ranging from 700 nm to 900 nm, which is better than that of commercial indocyanine green (ICG). Se@PPy nanocomposites have high photothermal conversion efficiency up to 36.3% as well as excellent photo-thermal stability. In vitro cytotoxicity test demonstrates that the Se@PPy nanocomposites have good bio-safety. Furthermore, the feasibility of Se@PPy nanocomposites for enhancing multi-spectral PAI guided PTT was verified on 4T1 tumor-bearing nude mice. Our results indicate that Se@PPy nanocomposites could be used as an effective theranostic agent for near-infrared light-mediated PAI and PTT of tumor. 相似文献
80.
A new controlled aging methodology was developed for the synthesis of PbS colloidal quantum dots (QDs), applying larger PbS QDs as a starting material for smaller QDs by application of environmentally friendly oleic acid and oleylamine as reagents. This simple and mild procedure provides a possible strategy for tailoring the size-dependent properties of PbS QDs. 相似文献