全文获取类型
收费全文 | 6009篇 |
免费 | 176篇 |
国内免费 | 13篇 |
专业分类
化学 | 3197篇 |
晶体学 | 32篇 |
力学 | 164篇 |
数学 | 647篇 |
物理学 | 2158篇 |
出版年
2022年 | 47篇 |
2021年 | 79篇 |
2020年 | 105篇 |
2019年 | 91篇 |
2018年 | 99篇 |
2017年 | 83篇 |
2016年 | 148篇 |
2015年 | 120篇 |
2014年 | 136篇 |
2013年 | 321篇 |
2012年 | 314篇 |
2011年 | 357篇 |
2010年 | 224篇 |
2009年 | 207篇 |
2008年 | 291篇 |
2007年 | 283篇 |
2006年 | 295篇 |
2005年 | 261篇 |
2004年 | 199篇 |
2003年 | 164篇 |
2002年 | 150篇 |
2001年 | 105篇 |
2000年 | 120篇 |
1999年 | 56篇 |
1998年 | 54篇 |
1997年 | 55篇 |
1996年 | 72篇 |
1995年 | 80篇 |
1994年 | 87篇 |
1993年 | 102篇 |
1992年 | 84篇 |
1991年 | 60篇 |
1990年 | 82篇 |
1989年 | 68篇 |
1988年 | 62篇 |
1987年 | 72篇 |
1986年 | 52篇 |
1985年 | 91篇 |
1984年 | 69篇 |
1983年 | 60篇 |
1982年 | 59篇 |
1981年 | 48篇 |
1980年 | 56篇 |
1979年 | 65篇 |
1978年 | 61篇 |
1977年 | 52篇 |
1976年 | 54篇 |
1975年 | 47篇 |
1974年 | 61篇 |
1973年 | 52篇 |
排序方式: 共有6198条查询结果,搜索用时 62 毫秒
1.
Analysis Mathematica - In this paper, in the light of weighted sharing of sets, we investigate the possible uniqueness of meromorphic function of restricted hyper order with its linear c-shift... 相似文献
2.
Molecular Diversity - Quantitative structure–activity relationship (QSAR) and read-across techniques have recently been merged into a new emerging field of read-across... 相似文献
3.
Archiv der Mathematik - Let G be a simple simply-connected connected linear algebraic group over $${\mathbb {C}}$$ . We prove a 2-birational Torelli theorem for the moduli space of semistable... 相似文献
4.
Sing Lai Cong Roy Anitha Hui Lok Yong Mun Chan Sook Rajak Harish Karunakaran Rohini Ravichandran Veerasamy 《Structural chemistry》2022,33(3):649-669
Structural Chemistry - Quinoline- and acridine-based drugs are widely used as anti-breast cancer agents. These drugs act through various mechanisms of action; for example, neratinib acts on... 相似文献
5.
Seema Yadav Sriparna Ray Ajeet Singh Shaikh M. Mobin Tapta Kanchan Roy Chandrakanta Dash 《应用有机金属化学》2020,34(11):e5942
Dinuclear gold(I)-N-heterocyclic carbene complexes were developed for the hydrohydrazidation of terminal alkynes. The gold(I)-N-heterocyclic carbene complexes 2a-2b were synthesized in good yields from silver complexes synthesized in situ, which in turn were obtained from the corresponding imidazolium salts with Ag2O in dichloromethane as a solvent. The new air-stable gold(I)-NHC complexes, 2a - 2b, were characterized using NMR spectroscopy, elemental analysis, infrared, and mass spectroscopy studies. The gold(I) complex 2a was characterized using X-ray crystallography. Bis-N-heterocyclic carbene–based gold(I) complexes 2a - 2b exhibited excellent catalytic activities for hydrohydrazidation of terminal alkynes yielding acylhydrazone derivatives. The working catalytic system can be used in gram-scale synthesis. In addition, the catalytic reaction mechanism of the hydrohydrazidation of terminal alkynes by gold(I)-NHC complex was studied in detail using density functional theory. 相似文献
6.
João Marcos G. Barbosa Milenna K. Fernandes Rodrigues Lurian C. David Taynara C. e Silva Danielly A. Fortuna Lima Naiara Z. Pereira Emmanuel B. D'Alessandro Anselmo E. de Oliveira Paulo H. Jorge da Cunha Maria Clorinda S. Fioravanti Nelson R. Antoniosi Filho 《Biomedical chromatography : BMC》2020,34(11):e4935
An innovative volatolomic approach employs the detection of biomarkers present in cerumen (earwax) to identify cattle intoxication by Stryphnodendron rotundifolium Mart., Fabaceae (popularly known as barbatimão). S. rotundifolium is a poisonous plant with the toxic compound undefined and widely distributed throughout the Brazilian territory. Cerumen samples from cattle of two local Brazilian breeds (‘Curraleiro Pé-Duro’ and ‘Pantaneiro’) were collected during an experimental intoxication protocol and analyzed using headspace (HS)/GC–MS followed by multivariate analysis (genetic algorithm for a partial least squares, cluster analysis, and classification and regression trees). A total of 106 volatile organic metabolites were identified in the cerumen samples of bovines. The intoxication by S. rotundifolium influenced the cerumen volatolomic profile of the bovines throughout the intoxication protocol. In this way, it was possible to detect biomarkers for cattle intoxication. Among the biomarkers, 2-octyldecanol and 9-tetradecen-1-ol were able to discriminate all samples between intoxicated and nonintoxicated bovines. The cattle intoxication diagnosis by S. rotundifolium was accomplished by applying the cerumen analysis using HS/GC–MS, in an easy, accurate, and noninvasive way. Thus, the proposed bioanalytical chromatography protocol is a useful tool in veterinary applications to determine this kind of intoxication. 相似文献
7.
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
8.
9.
10.