全文获取类型
收费全文 | 21490篇 |
免费 | 1322篇 |
国内免费 | 864篇 |
专业分类
化学 | 10011篇 |
晶体学 | 447篇 |
力学 | 1338篇 |
综合类 | 47篇 |
数学 | 2130篇 |
物理学 | 9703篇 |
出版年
2023年 | 194篇 |
2022年 | 361篇 |
2021年 | 378篇 |
2020年 | 417篇 |
2019年 | 391篇 |
2018年 | 461篇 |
2017年 | 447篇 |
2016年 | 621篇 |
2015年 | 571篇 |
2014年 | 680篇 |
2013年 | 1172篇 |
2012年 | 1416篇 |
2011年 | 1674篇 |
2010年 | 1215篇 |
2009年 | 1178篇 |
2008年 | 1301篇 |
2007年 | 1231篇 |
2006年 | 1240篇 |
2005年 | 1004篇 |
2004年 | 871篇 |
2003年 | 660篇 |
2002年 | 645篇 |
2001年 | 1016篇 |
2000年 | 711篇 |
1999年 | 599篇 |
1998年 | 368篇 |
1997年 | 385篇 |
1996年 | 289篇 |
1995年 | 244篇 |
1994年 | 210篇 |
1993年 | 185篇 |
1992年 | 197篇 |
1991年 | 168篇 |
1990年 | 156篇 |
1989年 | 128篇 |
1988年 | 115篇 |
1987年 | 92篇 |
1986年 | 84篇 |
1985年 | 93篇 |
1984年 | 68篇 |
1983年 | 43篇 |
1982年 | 41篇 |
1981年 | 33篇 |
1979年 | 27篇 |
1978年 | 25篇 |
1977年 | 23篇 |
1976年 | 34篇 |
1975年 | 34篇 |
1974年 | 25篇 |
1973年 | 24篇 |
排序方式: 共有10000条查询结果,搜索用时 156 毫秒
1.
Li Y. Shi W. H. Dong L. M. Xu S. X. Huang H. J. Yin J. R. 《Journal of Applied Spectroscopy》2022,89(3):534-541
Journal of Applied Spectroscopy - Sr3B2O6:Dy3+, Eu3+ single-matrix white-light-emitting materials are prepared using the high-temperature solid-state method. The microstructure, emission spectrum,... 相似文献
2.
Atopic dermatitis is characterized by leukocyte migration into the skin dermis and typically driven by excessive chemokine production at the site of inflammation. Conventional topical formulations such as gels, creams, and ointments are insufficient for this treatment because of low penetration of drug molecules into the targeted skin tissues. Herein, using a simple, green, sustainable strategy, we have developed novel primary zein nanoparticles embedded in curcumin (Cur) and coated with silk sericin (ZHSCs) for the topical delivery of Cur to penetrate into the dermis and exercise anti-dermatitis effects on the lesion with minimal side-effects. Transdermal delivery experiments and porcine skin fluorescence imaging indicated that ZHSCs facilitate the penetration of Cur across the epidermis layer of skin to reach deep-seated sites. Notably, ZHSCs = 1:0.25 (zein-to-silk sericin mass ratios of 1:0.25) markedly elevated the skin permeability and cumulative turnover of Cur transferred, which were provided a greater than a 3.8-fold increase relative to free Cur. The special nanoparticles of ZHS = 1:0.25 possessed the deepest localization depth and experience a transition of the particle structure and core-shell separation after penetrating into the dermis of skin. In a cell model of dermatitis induced by tumor necrosis factor α/interferon γ co-stimulation, compared with free Cur, Cur-loaded ZHS nanoparticles down-regulated the generation of inflammatory cytokines and chemokines in keratinocytes through suppression of the nuclear translocation of NF-κBp65 and hence exerted an anti-dermatitis effect. This strategy may provide new avenues and direction for the demanding issues of valid topical delivery systems. 相似文献
3.
Kai Cheng Xiao-Shuai Zhang Jie An Cheng Li Ruo-Yun Zhang Run Ye Prof. Dr. Bang-Jiao Ye Prof. Dr. Bo Liu Prof. Dr. Yuan-Di Zhao 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(31):7553-7560
Given their superior penetration depths, photosensitizers with longer absorption wavelengths present broader application prospects in photodynamic therapy (PDT). Herein, Ag2S quantum dots were discovered, for the first time, to be capable of killing tumor cells through the photodynamic route by near-infrared light irradiation, which means relatively less excitation of the probe compared with traditional photosensitizers absorbing short wavelengths. On modification with polydopamine (PDA), PDA-Ag2S was obtained, which showed outstanding capacity for inducing reactive oxygen species (increased by 1.69 times). With the addition of PDA, Ag2S had more opportunities to react with surrounding O2, which was demonstrated by typical triplet electron spin resonance (ESR) analysis. Furthermore, the PDT effects of Ag2S and PDA-Ag2S achieved at longer wavelengths were almost identical to the effects produced at 660 nm, which was proved by studies in vitro. PDA-Ag2S showed distinctly better therapeutic effects than Ag2S in experiments in vivo, which further validated the enhanced regulatory effect of PDA. Altogether, a new photosensitizer with longer absorption wavelength was developed by using the hitherto-unexplored photodynamic function of Ag2S quantum dots, which extended and enhanced the regulatory effect originating from PDA. 相似文献
4.
5.
Su X. F. Zhang Y. L. Maximov A. L. Zhang K. Xin Q. Feng C. Q. Bai X. F. Wu W. 《Russian Journal of Applied Chemistry》2020,93(1):127-136
Russian Journal of Applied Chemistry - Nanoscale ZSM-5 (AlZ5-D) and Ga-substituted ZSM-5 zeolites ((Al,Ga)Z5-D and GaZ5-D) were synthesized by a green dry-gel conversion strategy. For comparison,... 相似文献
6.
Journal of Thermal Analysis and Calorimetry - In the present work, pyrolysis kinetic mechanism was studied for regenerated cellulosic fiber (RCF) and composite RCF containing silicon/nitrogen flame... 相似文献
7.
采用粉末冶金法向铜基金属结合剂中引入玻璃料,结合材料电子万能试验机、洛氏硬度仪、SEM等检测方法,研究了玻璃料加入对铜基金属结合剂及金刚石磨具的影响.结果表明,随着玻璃料含量的增加,铜基结合剂的抗折强度和抗冲击强度呈下降的趋势,其硬度呈逐渐上升趋势,硬脆相的引入提高了铜基金属结合剂的自锐性;玻璃相和金属相之间结合紧密,两相之间化学元素在界面处发生相互扩散;玻璃料的加入使结合剂对磨料的包裹更加紧密,大大提高了结合剂对金刚石的把持力,有利于增加金刚石磨具寿命及加工效率. 相似文献
8.
Journal of Thermal Analysis and Calorimetry - A complete analysis of the thermal process about melamine was presented, in which different methods were applied to determine the characteristic of the... 相似文献
9.
10.
Kinetics and Catalysis - A series of Cu-SSZ-13@CeO2 catalysts with surface modification with CeO2 was prepared by the modified self-resemble method based on the one-pot synthesized Cu-SSZ-13... 相似文献