全文获取类型
收费全文 | 20421篇 |
免费 | 1082篇 |
国内免费 | 647篇 |
专业分类
化学 | 9074篇 |
晶体学 | 351篇 |
力学 | 1270篇 |
综合类 | 38篇 |
数学 | 2013篇 |
物理学 | 9404篇 |
出版年
2023年 | 168篇 |
2022年 | 253篇 |
2021年 | 265篇 |
2020年 | 282篇 |
2019年 | 244篇 |
2018年 | 349篇 |
2017年 | 306篇 |
2016年 | 501篇 |
2015年 | 422篇 |
2014年 | 632篇 |
2013年 | 1027篇 |
2012年 | 1292篇 |
2011年 | 1588篇 |
2010年 | 1165篇 |
2009年 | 1120篇 |
2008年 | 1224篇 |
2007年 | 1220篇 |
2006年 | 1210篇 |
2005年 | 980篇 |
2004年 | 841篇 |
2003年 | 628篇 |
2002年 | 598篇 |
2001年 | 995篇 |
2000年 | 672篇 |
1999年 | 589篇 |
1998年 | 414篇 |
1997年 | 421篇 |
1996年 | 341篇 |
1995年 | 276篇 |
1994年 | 283篇 |
1993年 | 212篇 |
1992年 | 230篇 |
1991年 | 208篇 |
1990年 | 178篇 |
1989年 | 167篇 |
1988年 | 132篇 |
1987年 | 121篇 |
1986年 | 84篇 |
1985年 | 90篇 |
1984年 | 66篇 |
1983年 | 45篇 |
1982年 | 32篇 |
1981年 | 36篇 |
1980年 | 18篇 |
1978年 | 17篇 |
1977年 | 18篇 |
1976年 | 27篇 |
1975年 | 27篇 |
1974年 | 20篇 |
1973年 | 19篇 |
排序方式: 共有10000条查询结果,搜索用时 107 毫秒
1.
Theoretical and Mathematical Physics - We apply the Riemann–Hilbert method to the generalized mixed nonlinear Schrödinger equation and obtain a new formula for an explicit $$N$$ -soliton... 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.
4.
Fluid Dynamics - To predict the boundary layer transition on swept wings, experimental and numerical researches were conducted to obtained the accurate boundary layer transition front and to... 相似文献
5.
Yu He Yating Guo Yanbin Yu Peifu Luo Honglong Qiu Guoming Huang 《Particle & Particle Systems Characterization》2021,38(5):2100038
In this study, manganese tellurite (MnTeO3) nanoparticles are developed as theranostic agents for magnetic resonance imaging (MRI)-guided photothermal therapy of tumor. MnTeO3 nanoparticles are synthesized via a simple one-step method. The as-synthesized MnTeO3 nanoparticles with uniform size show good biocompatibility. In particular, MnTeO3 nanoparticles exhibit a high photothermal conversion efficiency (η = 26.3%), which is higher than that of gold nanorods. Moreover, MnTeO3 nanoparticles also have high MRI performance. The longitudinal relaxivity (r1) value of MnTeO3 nanoparticles is determined to be 8.08 ± 0.2 mm −1 s−1, which is higher than that of clinically approved T1-contrast agents Gd-DTPA (4.49 ± 0.1 mm −1 s−1). The subsequent MnTeO3 nanoparticles-mediated photothermal therapy displays a highly efficient ablation of tumor cells both in vitro and in vivo with negligible toxicity. It is demonstrated that MnTeO3 nanoparticles can serve as promising theranostic agents with great potentials for MRI-guided photothermal therapy. 相似文献
6.
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
7.
Yining Liu Canhui Chen Jiuwen Qiu Zongbao Fang Haibo Wu Xingxian Zhang Shufang Wang 《Biomedical chromatography : BMC》2019,33(3)
Hongjingtian injection is made from Rhodiola wallichiana and used in the treatment of stable angina pectoris associated with coronary heart disease. In this study, the chemical constituents in Hongjingtian injection were comprehensively studied using liquid chromatography quadrupole time‐of‐flight mass spectrometry. A total of 49 compounds were identified or assumed, including 10 organic acids, nine phenylethanoids, 10 phenylpropanoids, two flavonoid glycosides, seven monoterpene glycosides, seven octylglycosides and four other types of compounds. The structures of seven compounds were confirmed by comparing their retention times, MS and UV spectra with the corresponding authentic standards. Amongst the 49 compounds, 35 were firstly found in R. wallichiana, while they have been reported in other species of the genus Rhodiola, including Rhodiola crenulata, Rhodiola sacra, Rhodiola rosea and Rhodiola kirilowii. The possible fragmentation pathways in the mass spectrometry of the major types of compounds are proposed and summarized. Our study demonstrates a rapid method for characterizing the chemical constituents present in the Hongjingtian injection, which could also be applied to the identification of chemical constituents in other TCM formulae containing R. wallichiana. 相似文献
8.
The chemical constituents of the fungus Verticillium psalliotae were studied. Two new aromadendrane sesquiterpenes inonotin M (1) and inonotin N (2) were isolated from the EtOAc extract of the fungal culture broth. The structures of compounds were elucidated mainly by HRESIMS experiments, and 1D, 2D-NMR spectroscopy analysis. 相似文献
9.
Introducing plasmonic metals into semiconductor materials has been proven to be an attractive strategy for enhancing photocatalytic activity in the visible region. In this work, a novel and efficient Ag/Ag2WO4/g‐C3N4 (AACN) ternary plasmonic photocatalyst was successfully synthesized using a facile one‐step in situ hydrothermal method. The composition, structure, morphology and optical absorption properties of AACN were investigated using X‐ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and UV–visible diffuse reflectance spectroscopy, respectively. Photocatalytic performance of AACN was evaluated via rhodamine B and tetracycline degradation. The results indicated that AACN had excellent photocatalytic performance for rhodamine B degradation with a rate constant of 0.0125 min?1, which was higher than those of Ag2WO4 and Ag/Ag2WO4. Characterization and photocatalytic tests showed that the strong coupling effect between the Ag/Ag2WO4 nanoparticles and the exfoliated ultrathin g‐C3N4 nanosheets was superior for visible‐light responsivity and reduced the recombination rate of photogenerated electrons and holes. A proposed mechanism is also discussed according to the band energy structure and the experimental results. 相似文献
10.