全文获取类型
收费全文 | 842篇 |
免费 | 13篇 |
国内免费 | 3篇 |
专业分类
化学 | 462篇 |
晶体学 | 3篇 |
力学 | 9篇 |
数学 | 132篇 |
物理学 | 252篇 |
出版年
2021年 | 11篇 |
2018年 | 7篇 |
2017年 | 5篇 |
2016年 | 9篇 |
2015年 | 12篇 |
2014年 | 14篇 |
2013年 | 44篇 |
2012年 | 27篇 |
2011年 | 53篇 |
2010年 | 30篇 |
2009年 | 17篇 |
2008年 | 35篇 |
2007年 | 37篇 |
2006年 | 42篇 |
2005年 | 34篇 |
2004年 | 30篇 |
2003年 | 22篇 |
2002年 | 20篇 |
2001年 | 16篇 |
2000年 | 14篇 |
1999年 | 8篇 |
1997年 | 7篇 |
1996年 | 13篇 |
1995年 | 9篇 |
1994年 | 16篇 |
1993年 | 15篇 |
1992年 | 17篇 |
1991年 | 11篇 |
1990年 | 7篇 |
1989年 | 7篇 |
1988年 | 10篇 |
1987年 | 10篇 |
1986年 | 15篇 |
1985年 | 22篇 |
1984年 | 10篇 |
1983年 | 11篇 |
1982年 | 5篇 |
1981年 | 14篇 |
1980年 | 17篇 |
1979年 | 11篇 |
1978年 | 15篇 |
1977年 | 20篇 |
1976年 | 11篇 |
1975年 | 18篇 |
1974年 | 6篇 |
1973年 | 10篇 |
1972年 | 7篇 |
1970年 | 5篇 |
1968年 | 5篇 |
1966年 | 5篇 |
排序方式: 共有858条查询结果,搜索用时 768 毫秒
1.
Algebras and Representation Theory - We would like to correct two errors in our paper Involutions of type G2 over a field of characteristic 2 [2]. 相似文献
2.
3.
4.
The concepts of a linear covering code and a covering set for the limited-magnitude-error channel are introduced. A number of covering-set constructions, as well as some bounds, are given. In particular, optimal constructions are given for some cases involving small-magnitude errors. A problem of Stein is partially solved for these cases. Optimal packing sets and the corresponding error-correcting codes are also considered for some small-magnitude errors. 相似文献
5.
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
6.
Graphitic‐Carbon Layers on Oxides: Toward Stable Heterogeneous Catalysts for Biomass Conversion Reactions 下载免费PDF全文
Dr. Haifeng Xiong Thomas J. Schwartz Nalin I. Andersen Prof. James A. Dumesic Prof. Abhaya K. Datye 《Angewandte Chemie (International ed. in English)》2015,54(27):7939-7943
Conversion of biomass‐derived molecules involves catalytic reactions under harsh conditions in the liquid phase (e.g., temperatures of 250 °C and possibly under either acidic or basic conditions). Conventional oxide‐supported catalysts undergo pore structure collapse and surface area reduction leading to deactivation under these conditions. Here we demonstrate an approach to deposit graphitic carbon to protect the oxide surface. The heterogeneous catalysts supported on the graphitic carbon/oxide composite exhibit excellent stability (even under acidic conditions) for biomass conversion reactions. 相似文献
7.
I. Alencar J. Ruiz‐Fuertes K. Schwartz C. Trautmann L. Bayarjargal E. Haussühl B. Winkler 《Journal of Raman spectroscopy : JRS》2016,47(8):978-983
The formation conditions and dynamics of Ca colloids and point defects that appear in irradiated single crystals of CaF2 were investigated by Raman spectroscopy. The intensity changes in the Raman spectra because of the presence of different concentrations of point defects and Ca colloids that emerged in CaF2 after irradiation with 2.2 GeV Au ions were used to study their distribution and stability under illumination with three laser wavelengths (473, 532 and 633 nm) at different output powers (2 to 200 mW). A damage saturation at a fluence of 6 × 1011 ion cm−2 was observed. The dependence of the spectral changes on the ion fluence can be described by a core/halo damage cross‐section model. A radius of 13–18 nm was obtained for the outer (halo) cylinder, in agreement with previous swelling studies. Illuminations of irradiated samples with blue (473 nm) and green (532 nm) lasers were found to be extremely efficient in bleaching the samples, while illumination with a red (633 nm) laser did not lead to a sample recovery. This indicates that the bleaching process is governed by recombination of point defects that have to overcome an energy barrier. Typical time constants for the processes involved are presented. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
8.
9.
10.