全文获取类型
收费全文 | 26381篇 |
免费 | 3592篇 |
国内免费 | 2493篇 |
专业分类
化学 | 12957篇 |
晶体学 | 186篇 |
力学 | 1049篇 |
综合类 | 108篇 |
数学 | 1819篇 |
物理学 | 7278篇 |
综合类 | 9069篇 |
出版年
2024年 | 146篇 |
2023年 | 515篇 |
2022年 | 834篇 |
2021年 | 909篇 |
2020年 | 872篇 |
2019年 | 800篇 |
2018年 | 759篇 |
2017年 | 663篇 |
2016年 | 1009篇 |
2015年 | 1056篇 |
2014年 | 1331篇 |
2013年 | 1546篇 |
2012年 | 1916篇 |
2011年 | 1828篇 |
2010年 | 1371篇 |
2009年 | 1342篇 |
2008年 | 1457篇 |
2007年 | 1362篇 |
2006年 | 1282篇 |
2005年 | 1150篇 |
2004年 | 870篇 |
2003年 | 737篇 |
2002年 | 768篇 |
2001年 | 702篇 |
2000年 | 602篇 |
1999年 | 876篇 |
1998年 | 773篇 |
1997年 | 734篇 |
1996年 | 692篇 |
1995年 | 630篇 |
1994年 | 525篇 |
1993年 | 433篇 |
1992年 | 380篇 |
1991年 | 326篇 |
1990年 | 328篇 |
1989年 | 251篇 |
1988年 | 219篇 |
1987年 | 141篇 |
1986年 | 98篇 |
1985年 | 78篇 |
1984年 | 34篇 |
1983年 | 31篇 |
1982年 | 32篇 |
1981年 | 19篇 |
1980年 | 12篇 |
1979年 | 3篇 |
1977年 | 3篇 |
1942年 | 2篇 |
1930年 | 2篇 |
1916年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
Hongming He Qian‐Qian Zhu Chuanqi Zhang Ying Yan Jing Yuan Jing Chen Cheng‐Peng Li Miao Du 《化学:亚洲杂志》2019,14(7):917-917
993.
Herein we summarized some clean preparation examples to emphasize the concept of dual roles design (or named as “two birds one stone strategy”) in green and sustainable chemistry. In those examples, the reactants and/or solvent play dual roles rendering a cleaner organic preparation process. Consequently, both the chemical waste and manufacturing cost could be reduced. 相似文献
994.
995.
Flapping-powered propulsion is used by many animals to locomote through air or water. Here we review recent experimental and numerical studies on self-propelled mechanical systems powered by a flapping motion. These studies improve our understanding of the mutual interaction between actively flapping bodies and surrounding fluids. The results obtained in these works provide not only new insights into biolocomotion but also useful information for the bio-mimetic design of artificial flyers and swimmers. 相似文献
996.
997.
998.
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
999.
Journal of Radioanalytical and Nuclear Chemistry - The stable isotope-labeled rosuvastatin was requested in order to fully understand the metabolic process of rosuvastatin. An effective synthesis... 相似文献
1000.
Jing He Mohan Yu Maofu Pang Yanqing Fan Zhe Lian Dr. Ying Wang Prof. Wenguang Wang Prof. Yajun Liu Prof. Hua Jiang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(13):e202103832
Structural designs combining cycloparaphenylenes (CPPs) backbone with planar chiral [2.2]paracyclophane ([2.2]PCP) lead to optical-active chiral macrocycles with intriguing properties. X-ray crystal analysis revealed aesthetic necklace-shaped structures and size-dependent packages with long-range channels. The macrocycles exhibit unique photophysical properties with high fluorescence quantum yield of up to 82 %, and the fluorescent color varies with ring size. In addition, size-dependent chiroptical properties with moderately large CPL dissymmetry factor of 10−3 and CPL brightness in the range of 30–40 M−1 cm−1 were observed. 相似文献