全文获取类型
收费全文 | 157599篇 |
免费 | 19011篇 |
国内免费 | 14355篇 |
专业分类
化学 | 72462篇 |
晶体学 | 1135篇 |
力学 | 5876篇 |
综合类 | 676篇 |
数学 | 12677篇 |
物理学 | 39561篇 |
综合类 | 58578篇 |
出版年
2024年 | 638篇 |
2023年 | 2693篇 |
2022年 | 4532篇 |
2021年 | 4828篇 |
2020年 | 4830篇 |
2019年 | 4244篇 |
2018年 | 4239篇 |
2017年 | 3919篇 |
2016年 | 5709篇 |
2015年 | 6210篇 |
2014年 | 8068篇 |
2013年 | 9656篇 |
2012年 | 11380篇 |
2011年 | 11699篇 |
2010年 | 8849篇 |
2009年 | 8781篇 |
2008年 | 9457篇 |
2007年 | 8720篇 |
2006年 | 7946篇 |
2005年 | 7110篇 |
2004年 | 5450篇 |
2003年 | 4684篇 |
2002年 | 4496篇 |
2001年 | 4165篇 |
2000年 | 3637篇 |
1999年 | 4711篇 |
1998年 | 3983篇 |
1997年 | 3806篇 |
1996年 | 3662篇 |
1995年 | 3149篇 |
1994年 | 2867篇 |
1993年 | 2348篇 |
1992年 | 2072篇 |
1991年 | 1886篇 |
1990年 | 1551篇 |
1989年 | 1385篇 |
1988年 | 1068篇 |
1987年 | 754篇 |
1986年 | 580篇 |
1985年 | 341篇 |
1984年 | 207篇 |
1983年 | 156篇 |
1982年 | 126篇 |
1981年 | 78篇 |
1980年 | 59篇 |
1979年 | 26篇 |
1978年 | 22篇 |
1976年 | 24篇 |
1975年 | 22篇 |
1957年 | 26篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
Yang T. L. Kao C. L. Kuo C. E. Yeh H. C. Li W. J. Li H. T. Chen C. Y. 《Chemistry of Natural Compounds》2022,58(5):825-827
Chemistry of Natural Compounds - A novel bibenzyl derivative, hydrangchinenin (1), was isolated from the stems of Hydrangea chinensis Maxim. (Hydrangeaceae). Its structure was determined on the... 相似文献
2.
3.
Chen Zi-Han Li Yue-Hua Qi Ming-Yu Tang Zi-Rong Xu Yi-Jun 《Research on Chemical Intermediates》2022,48(1):1-12
Research on Chemical Intermediates - Owing to the simultaneous utilization of photogenerated electrons and holes, coupling light-driven hydrogen (H2) evolution reaction (HER) and biomass-derived... 相似文献
4.
Zhang Bing Yang Jie-qin Liu Ying Hu Bin Yang Yang Zhao Li Lu Qiang 《Cellulose (London, England)》2022,29(12):6565-6578
Cellulose - Heating is essential in various biomass pre-treatments and thermal conversion processes. It is of practical significance to study the characteristics of cellulose-lignin and... 相似文献
5.
Guo-Xing Li Xiao-Wei Qu Lu-Wei Hao Qing Li Su Chen 《Journal of polymer science. Part A, Polymer chemistry》2022,60(11):1710-1717
From the implementation point of view, the printable magnetic Janus colloidal photonic crystals (CPCs) microspheres are highly desirable. Herein, we developed a dispensing-printing strategy for magnetic Janus CPCs display via a microfluidics-automatic printing system. Monodisperse core/shell colloidal particles and magnetic Fe3O4 nanoparticles precursor serve as inks. Based on the equilibrium of three-phase interfacial tensions, Janus structure is successfully formed, followed by UV irradiation and self-assembly of colloid particle to generate magnetic Janus CPCs microspheres. Notably, this method shows distinct superiority with highly uniform Janus CPCs structure, where the TMPTA/Fe3O4 hemisphere is in the bottom side while CPCs hemisphere is in the top side. Thus, by using Janus CPCs microspheres with two different structural colors as pixel points, a pattern with red flower and green leaf is achieved. Moreover, 1D linear Janus CPCs pattern encapsulated by hydrogel is also fabricated. Both the color and the shape can be changed under the traction of magnets, showing great potentials in flexible smart displays. We believe this work not only offers a new feasible pathway to construct magnetic Janus CPCs patterns by a dispensing-printable fashion, but also provides new opportunities for flexible and smart displays. 相似文献
6.
Yujie Gao Zhiye Qiu Lei Liu Mengmeng Li Bingjie Xu Dan Yu Dongming Qi Jindan Wu 《Journal of polymer science. Part A, Polymer chemistry》2022,60(15):2191-2212
Refractory wounds have always been an important issue to healthcare systems, whose healing process is always delayed by multiple factors, including bacterial infections, chronic inflammation, and excessive exudates, etc. Employing multifunctional wound dressings is recognized as an effective strategy to deal with refractory wounds, which has yielded promising outcomes in recent years. Among these advanced wound dressings, fibrous dressings have gained growing attention due to their unique merits. Such wound dressings have demonstrated great potential in delivering theranostic agents, such as antibacterial agents, anti-inflammatory drugs, growth factors, and diagnostic probes, etc., for the purposes of accelerating wound healing. This paper reviews the development of multifunctional fibrous dressings and their applications in treating refractory wounds. The construction approaches of novel fibrous dressing with capabilities of antibacterial, anti-inflammation, exudate management and diagnosis were also introduced. Furthermore, the existing problems and challenges are also discussed briefly. 相似文献
7.
8.
9.
10.
中医古文献蕴藏着丰富的临床经验,是古代中医在行医过程中对临床诊疗的经验性总结,体现了中医学形成和发展的理论框架和思想基础.然而这些宝贵的临床经验不仅量大,而且分散在不同的文献中,使得中医从业者手工很难快速全面地获取它们,文献检索工具也只能提供文档级别的信息筛选,无法为这种细粒度的信息获取提供支持.此外,古汉语相对于现代汉语的不同特点也限制了主流文本分析工具的使用效果.为此本文提出面向临床经验获取的中医古文献信息抽取任务,用于识别古文献中描述临床经验的文本片段,手工标注了样本数据用于这种抽取模型的训练和测试,并设计了基于深度学习的序列标注器用于完成该任务.考虑到标注数据量小可能带来的过度拟合问题,本文引入对抗训练和虚拟对抗训练来增强模型的泛化能力.一系列充分的实验验证了模型的有效性,表明利用信息抽取技术从古文献获取中医临床经验具有可行性,为这一新的信息抽取任务提供了有希望的研究基线和可复用的标注数据集. 相似文献