全文获取类型
收费全文 | 1518篇 |
免费 | 24篇 |
国内免费 | 12篇 |
专业分类
化学 | 684篇 |
晶体学 | 5篇 |
力学 | 25篇 |
数学 | 427篇 |
物理学 | 413篇 |
出版年
2021年 | 10篇 |
2020年 | 11篇 |
2019年 | 12篇 |
2018年 | 19篇 |
2017年 | 14篇 |
2016年 | 24篇 |
2015年 | 17篇 |
2014年 | 23篇 |
2013年 | 77篇 |
2012年 | 53篇 |
2011年 | 79篇 |
2010年 | 41篇 |
2009年 | 29篇 |
2008年 | 59篇 |
2007年 | 69篇 |
2006年 | 80篇 |
2005年 | 70篇 |
2004年 | 53篇 |
2003年 | 42篇 |
2002年 | 43篇 |
2001年 | 24篇 |
2000年 | 29篇 |
1999年 | 18篇 |
1998年 | 11篇 |
1997年 | 15篇 |
1996年 | 31篇 |
1995年 | 20篇 |
1994年 | 31篇 |
1993年 | 29篇 |
1992年 | 37篇 |
1991年 | 21篇 |
1990年 | 20篇 |
1989年 | 15篇 |
1988年 | 15篇 |
1987年 | 15篇 |
1986年 | 20篇 |
1985年 | 37篇 |
1984年 | 26篇 |
1983年 | 23篇 |
1982年 | 20篇 |
1981年 | 28篇 |
1980年 | 26篇 |
1979年 | 24篇 |
1978年 | 23篇 |
1977年 | 27篇 |
1976年 | 17篇 |
1975年 | 30篇 |
1974年 | 15篇 |
1973年 | 13篇 |
1972年 | 9篇 |
排序方式: 共有1554条查询结果,搜索用时 15 毫秒
81.
Marek Konop Anna K. Laskowska Mateusz Rybka Ewa Kodziska Dorota Sulejczak Robert A. Schwartz Joanna Czuwara 《Molecules (Basel, Switzerland)》2021,26(9)
Impaired wound healing is a major medical challenge, especially in diabetics. Over the centuries, the main goal of tissue engineering and regenerative medicine has been to invent biomaterials that accelerate the wound healing process. In this context, keratin-derived biomaterial is a promising candidate due to its biocompatibility and biodegradability. In this study, we evaluated an insoluble fraction of keratin containing casomorphin as a wound dressing in a full-thickness surgical skin wound model in mice (n = 20) with iatrogenically induced diabetes. Casomorphin, an opioid peptide with analgesic properties, was incorporated into keratin and shown to be slowly released from the dressing. An in vitro study showed that keratin-casomorphin dressing is biocompatible, non-toxic, and supports cell growth. In vivo experiments demonstrated that keratin-casomorphin dressing significantly (p < 0.05) accelerates the whole process of skin wound healing to the its final stage. Wounds covered with keratin-casomorphin dressing underwent reepithelization faster, ending up with a thicker epidermis than control wounds, as confirmed by histopathological and immunohistochemical examinations. This investigated dressing stimulated macrophages infiltration, which favors tissue remodeling and regeneration, unlike in the control wounds in which neutrophils predominated. Additionally, in dressed wounds, the number of microhemorrhages was significantly decreased (p < 0.05) as compared with control wounds. The dressing was naturally incorporated into regenerating tissue during the wound healing process. Applied keratin dressing favored reconstruction of more regular skin structure and assured better cosmetic outcome in terms of scar formation and appearance. Our results have shown that insoluble keratin wound dressing containing casomorphin supports skin wound healing in diabetic mice. 相似文献
82.
Koranit Shlosman Ran Y. Suckeveriene Jasmine Rosen‐Kligvasser Roza Tchoudakov Evgeni Zelikman Raphael Semiat Moshe Narkis 《先进技术聚合物》2014,25(12):1484-1491
This paper summarizes a study of controlled migration of an antifog (AF) additive; sorbitan monooleate (SMO), from linear low density polyethylene (LLDPE) films containing a compatibilizer, LLDPE grafted maleic anhydride (LLDPE‐g‐MA). LLDPE/LLDPE‐g‐MA/SMO blends were prepared by melt compounding. Bulk and surface properties of compression molded LLDPE films containing SMO and LLDPE‐g‐MA were characterized using Fourier transform infrared spectroscopy and contact angle measurements. Thermal properties were investigated using a thermal gravimetric analyzer. Diffusion coefficient (D) was calculated, and AF properties were characterized using a “hot fog” test. Compression molded films were characterized for their morphology using high‐resolution scanning electron microscopy, and rheological properties were measured using a parallel‐plate rotational rheometer. It was found that the LLDPE/LLDPE‐g‐MA/SMO systems are characterized by a slower SMO migration rate, a lower diffusion coefficient, and lower contact angle values compared with LLDPE/SMO blends. These results are well correlated with results of a hot fog test. Morphological studies revealed a very fine dispersion of SMO in the LLDPE films, when 3 phr LLDPE‐g‐MA was combined with 1 phr SMO. Thermal analysis results show that the incorporation of 3 phr LLDPE‐g‐MA and 1 phr SMO significantly increases the decomposition temperature of the blend at T > 400°C. At high shear rates, the LLDPE blends show that the AF and the compatibilizer have a lubrication effect on LLDPE. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
83.
Frontispiece: Engineering Catalyst Microenvironments for Metal‐Catalyzed Hydrogenation of Biologically Derived Platform Chemicals
下载免费PDF全文
![点击此处可从《Angewandte Chemie (International ed. in English)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
84.
85.
86.
87.
Wan Yong Feng Moshe Goldenberg Chava Lifshitz 《Journal of the American Society for Mass Spectrometry》1994,5(8):695-703
Thermal reactions of proton-bound dimers, (CH3CN)2H +, (CH3OCH3)2H +, and (CH3COCH3)2H+, were studied using a selected ion flow tube. Reactions observed include association, switching, and proton transfer. The association channel was observed only for base molecules that had hydrogen bonding protons such as NH3, CH3NH2, (CH3)2NH, and CH3OH. An association-insertion mechaniSoc was proposed in which the central proton of the symmetrically bound dimers is replaced by a protonated base, for example, NH 4 + . These reactions are relatively slow, which demonstrates a central barrier along the potential energy surface. Ether-containing dimers do not demonstrate this insertion reaction, except for diethers, for example, CH3OCH2CH2OCH3, which can form stable bicyclic structures. Dimers such as (HCOOH)2H+, which possess hydrogen bonding protons in the periphery, undergo switching reactions with ammonia and no insertion. 相似文献
88.
Brenda L. Schwartz Karen J. Light-Wahl Richard D. Smith 《Journal of the American Society for Mass Spectrometry》1994,5(3):201-204
Intact avidin-biotin and avidin-biotin maleimide noncovalent complexes have been observed by electrospray ionization mass spectrometry (ESI-MS) by using an extended mass range quadrupole mass spectrometer. By utilizing mild ES1 interface conditions, the expected solution behavior of four biotin or biotin maleimide molecules noncovalently binding to each avidin tetramer can be preserved in the gas phase. The ESI-MS results show the appropriate mass additions of 973 ± 60 Da for biotin and 1802 ± 40 Da for biotin maleimide to the avidin tetramer species. These results support the hypothesis that substantial retention of higher order structure is possible in the gas phase by using gentle ESI conditions. 相似文献
89.
90.