全文获取类型
收费全文 | 20098篇 |
免费 | 3304篇 |
国内免费 | 3907篇 |
专业分类
化学 | 15550篇 |
晶体学 | 519篇 |
力学 | 926篇 |
综合类 | 385篇 |
数学 | 2689篇 |
物理学 | 7240篇 |
出版年
2024年 | 45篇 |
2023年 | 259篇 |
2022年 | 588篇 |
2021年 | 643篇 |
2020年 | 755篇 |
2019年 | 776篇 |
2018年 | 624篇 |
2017年 | 762篇 |
2016年 | 872篇 |
2015年 | 984篇 |
2014年 | 1179篇 |
2013年 | 1533篇 |
2012年 | 1797篇 |
2011年 | 1849篇 |
2010年 | 1541篇 |
2009年 | 1510篇 |
2008年 | 1748篇 |
2007年 | 1497篇 |
2006年 | 1395篇 |
2005年 | 1139篇 |
2004年 | 860篇 |
2003年 | 716篇 |
2002年 | 864篇 |
2001年 | 679篇 |
2000年 | 510篇 |
1999年 | 382篇 |
1998年 | 254篇 |
1997年 | 175篇 |
1996年 | 197篇 |
1995年 | 151篇 |
1994年 | 145篇 |
1993年 | 138篇 |
1992年 | 115篇 |
1991年 | 115篇 |
1990年 | 91篇 |
1989年 | 75篇 |
1988年 | 52篇 |
1987年 | 46篇 |
1986年 | 39篇 |
1985年 | 45篇 |
1984年 | 29篇 |
1983年 | 25篇 |
1982年 | 20篇 |
1981年 | 13篇 |
1980年 | 10篇 |
1979年 | 10篇 |
1978年 | 11篇 |
1977年 | 9篇 |
1976年 | 6篇 |
1973年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 689 毫秒
741.
742.
Zheng-Wang Chen Dong-Nai Ye Min YeZhong-Gao Zhou Shen-Huan LiLiang-Xian Liu 《Tetrahedron letters》2014
A AgF/TFA-promoted highly efficient synthesis of a wide range of α-haloketones from haloalkynes is described. The reactions are conducted under convenient conditions and provide products in moderate to excellent yields, with broad substrate scope, including a variety of aromatic chloroalkynes and bromoalkynes. 相似文献
743.
Jia Min Lee Sean Kang Qiang Suen Wei Long Ng Wai Cheung Ma Wai Yee Yeong 《Macromolecular bioscience》2021,21(1)
Collagen is the most abundant extracellular matrix protein that is widely used in tissue engineering (TE). There is little research done on printing pure collagen. To understand the bottlenecks in printing pure collagen, it is imperative to understand collagen from a bottom‐up approach. Here it is aimed to provide a comprehensive overview of collagen printing, where collagen assembly in vivo and the various sources of collagen available for TE application are first understood. Next, the current printing technologies and strategy for printing collagen‐based materials are highlighted. Considerations and key challenges faced in collagen printing are identified. Finally, the key research areas that would enhance the functionality of printed collagen are presented. 相似文献
744.
Jiahao Liu Weikang Li Dr. Yinwu Li Prof. Dr. Yan Liu Prof. Dr. Zhuofeng Ke 《化学:亚洲杂志》2021,16(20):3124-3128
The first implementation of a molybdenum complex with an easily accessible bis-N-heterocyclic carbene ligand to catalyze β-alkylation of secondary alcohols via borrowing-hydrogen (BH) strategy using alcohols as alkylating agents is reported. Remarkably high activity, excellent selectivity, and broad substrate scope compatibility with advantages of catalyst usage low to 0.5 mol%, a catalytic amount of NaOH as the base, and H2O as the by-product are demonstrated in this green and step-economical protocol. Mechanistic studies indicate a plausible outer-sphere mechanism in which the alcohol dehydrogenation is the rate-determining step. 相似文献
745.
Chang Su Jin‐Song Gong Jin‐Peng Ye Ji‐Meng He Rui‐Yi Li Min Jiang Yan Geng Yan Zhang Jing‐Hua Chen Zheng‐Hong Xu Jin‐Song Shi 《Macromolecular bioscience》2020,20(9)
Keratin is widely recognized as a high‐quality renewable protein resource for biomedical applications. Despite their extensive existence, keratin resources such as feathers, wool, and hair exhibit high stability and mechanical properties because of their high disulfide bond content. Consequently, keratin extraction is challenging and its application is greatly hindered. In this work, a biological extraction strategy is proposed for the preparation of bioactive keratin and the fabrication of self‐assembled keratin hydrogels (KHs). Based on moderate and controlled hydrolysis by keratinase, keratin with a high molecular weight of approximately 45 and 28 kDa that retain its intrinsic bioactivities is obtained. The keratin products show excellent ability to promote cell growth and migration and are conferred with significant antioxidant ability because of their intrinsically high cysteine content. In addition, without the presence of any cross‐linking agent, the extracted keratin can self‐assemble into injectable hydrogels. The KHs exhibit a porous network structure and 3D culture ability, showing potential in promoting wound healing. This enzyme‐driven keratin extraction strategy opens up a new approach for the preparation of keratin that can self‐assemble into injectable hydrogels for biomedical engineering. 相似文献
746.
Long-term pulmonary exposure to multi-walled carbon nanotubes (MWCNTs) may promote breast cancer metastasis and rapid colonization in the lungs and other organs according to recent research conducted by Prof.Chunying Chen,Prof.Tao Zhu and their colleagues,published in Nature Nanotechnology [1]. 相似文献
747.
748.
Liu Yu-Xuan Wang Liang Zhou Ke Wu Hong-Bo Zhou Xiao-Bo Ma Zai-Fei Guo Sheng-Wei Ma Wei 《高分子科学》2022,40(8):951-959
Chinese Journal of Polymer Science - The aligned molecular packing structure is vital to the anisotropic charge transport in conjugated polymer and small molecule thin films. However, how this... 相似文献
749.