全文获取类型
收费全文 | 1973篇 |
免费 | 44篇 |
国内免费 | 3篇 |
专业分类
化学 | 1013篇 |
晶体学 | 8篇 |
力学 | 39篇 |
数学 | 207篇 |
物理学 | 753篇 |
出版年
2022年 | 10篇 |
2021年 | 23篇 |
2020年 | 30篇 |
2019年 | 18篇 |
2018年 | 14篇 |
2017年 | 24篇 |
2016年 | 40篇 |
2015年 | 41篇 |
2014年 | 32篇 |
2013年 | 69篇 |
2012年 | 90篇 |
2011年 | 95篇 |
2010年 | 65篇 |
2009年 | 62篇 |
2008年 | 88篇 |
2007年 | 82篇 |
2006年 | 80篇 |
2005年 | 83篇 |
2004年 | 75篇 |
2003年 | 53篇 |
2002年 | 64篇 |
2001年 | 34篇 |
2000年 | 52篇 |
1999年 | 13篇 |
1998年 | 15篇 |
1997年 | 18篇 |
1996年 | 33篇 |
1995年 | 32篇 |
1994年 | 44篇 |
1993年 | 48篇 |
1992年 | 41篇 |
1991年 | 27篇 |
1990年 | 33篇 |
1989年 | 28篇 |
1988年 | 25篇 |
1987年 | 34篇 |
1986年 | 23篇 |
1985年 | 47篇 |
1984年 | 31篇 |
1983年 | 21篇 |
1982年 | 24篇 |
1981年 | 15篇 |
1980年 | 18篇 |
1979年 | 33篇 |
1978年 | 24篇 |
1977年 | 19篇 |
1976年 | 17篇 |
1975年 | 17篇 |
1974年 | 27篇 |
1973年 | 16篇 |
排序方式: 共有2020条查询结果,搜索用时 31 毫秒
1.
2.
Ashley M. Nelson Sean T. Hemp Jessica Chau Timothy E. Long 《Journal of polymer science. Part A, Polymer chemistry》2015,53(24):2829-2837
The incorporation of acrylic functionality into caffeine enables the preparation of a vast array of novel thermoplastics and thermosets. A two‐step derivatization provided a novel caffeine‐containing methacrylate monomer capable of free radical polymerization. Copolymers of 2‐ethylhexyl methacrylate and caffeine methacrylate (CMA) allowed for a systematic study of the effect of covalently bound caffeine on polymer properties. 1H NMR and UV‐vis spectroscopy confirmed caffeine incorporation at 5 and 13 mol %, and SEC revealed the formation of high molecular weight (co)polymers (>40,000 g/mol). CMA incorporation resulted in a multistep degradation profile with initial mass loss closely correlating to caffeine content. Differential scanning calorimetry, rheological, and thermomechanical analysis demonstrated that relatively low levels of CMA increased the glass transition temperature, resulting in higher moduli and elucidating the benefits of incorporating caffeine into polymers. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 2829–2837 相似文献
3.
4.
Beatriz F. dos Santos Caroline F. Pereira Mikaela P. Pinz Aline R. de Oliveira George Brand Ramesh Katla Ethel A. Wilhelm Cristiane Luchese Nelson L.C. Domingues 《应用有机金属化学》2020,34(7):e5650
Functionalization of 2,1,3-benzothiadiazole (BTD) with thiols at C-5 position remains low explored. Moreover, the arylthiol-substitutions at this position are also unexplored and can not be found by a SN2 or SN1 reaction. In this sense, herein we present a new palladium-catalyzed methodology for a wide variety of unpublished 5-arylsulfanyl-benzo-2,1,3-thiadiazole derivatives synthesis with moderate to high yields using a low catalytic loading of Pd(L-Pro)2 as low-coast, and efficient catalyst in low reaction time. Besides, we concluded that the pKa of thiol species has an important role in this catalysis, mainly in the CMD like catalytic cyclo process, which strongly interferes in the reaction yields. Furthermore, arylsulfanyl-benzo-2,1,3-thiadiazoles derivatives have been assessed (in vitro) as potential acetylcholinesterase inhibitors. 相似文献
5.
Adam I. Green Dr. Fruzsina Hobor Dr. Christopher P. Tinworth Dr. Stuart Warriner Prof. Andrew J. Wilson Prof. Adam Nelson 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(47):10682-10689
Protein–protein interactions (PPIs) provide a rich source of potential targets for drug discovery and biomedical science research. However, the identification of structural-diverse starting points for discovery of PPI inhibitors remains a significant challenge. Activity-directed synthesis (ADS), a function-driven discovery approach, was harnessed in the discovery of the p53/hDM2 PPI. Over two rounds of ADS, 346 microscale reactions were performed, with prioritisation on the basis of the activity of the resulting product mixtures. Four distinct and novel series of PPI inhibitors were discovered that, through biophysical characterisation, were shown to have promising ligand efficiencies. It was thus shown that ADS can facilitate ligand discovery for a target that does not have a defined small-molecule binding site, and can provide distinctive starting points for the discovery of PPI inhibitors. 相似文献
6.
Dr. Oscar Tutusaus Dr. Rana Mohtadi Dr. Timothy S. Arthur Dr. Fuminori Mizuno Dr. Emily G. Nelson Prof. Yulia V. Sevryugina 《Angewandte Chemie (International ed. in English)》2015,54(27):7900-7904
Unlocking the full potential of rechargeable magnesium batteries has been partially hindered by the reliance on chloride‐based complex systems. Despite the high anodic stability of these electrolytes, they are corrosive toward metallic battery components, which reduce their practical electrochemical window. Following on our new design concept involving boron cluster anions, monocarborane CB11H12? produced the first halogen‐free, simple‐type Mg salt that is compatible with Mg metal and displays an oxidative stability surpassing that of ether solvents. Owing to its inertness and non‐corrosive nature, the Mg(CB11H12)2/tetraglyme (MMC/G4) electrolyte system permits standardized methods of high‐voltage cathode testing that uses a typical coin cell. This achievement is a turning point in the research and development of Mg electrolytes that has deep implications on realizing practical rechargeable Mg batteries. 相似文献
7.
8.
9.
Growth under Visible Light Increases Conidia and Mucilage Production and Tolerance to UV‐B Radiation in the Plant Pathogenic Fungus Colletotrichum acutatum 下载免费PDF全文
Henrique D. de Menezes Nelson S. Massola Jr Stephan D. Flint Geraldo J. Silva Jr Luciano Bachmann Drauzio E. N. Rangel Gilberto U. L. Braga 《Photochemistry and photobiology》2015,91(2):397-402
Light conditions can influence fungal development. Some spectral wavebands can induce conidial production, whereas others can kill the conidia, reducing the population size and limiting dispersal. The plant pathogenic fungus Colletotrichum acutatum causes anthracnose in several crops. During the asexual stage on the host plant, Colletototrichum produces acervuli with abundant mucilage‐embedded conidia. These conidia are responsible for fungal dispersal and host infection. This study examined the effect of visible light during C. acutatum growth on the production of conidia and mucilage and also on the UV tolerance of these conidia. Conidial tolerance to an environmentally realistic UV irradiance was determined both in conidia surrounded by mucilage on sporulating colonies and in conidial suspension. Exposures to visible light during fungal growth increased production of conidia and mucilage as well as conidial tolerance to UV. Colonies exposed to light produced 1.7 times more conidia than colonies grown in continuous darkness. The UV tolerances of conidia produced under light were at least two times higher than conidia produced in the dark. Conidia embedded in the mucilage on sporulating colonies were more tolerant of UV than conidia in suspension that were washed free of mucilage. Conidial tolerance to UV radiation varied among five selected isolates. 相似文献
10.