全文获取类型
收费全文 | 117340篇 |
免费 | 5245篇 |
国内免费 | 3100篇 |
专业分类
化学 | 63062篇 |
晶体学 | 1802篇 |
力学 | 6315篇 |
综合类 | 283篇 |
数学 | 11156篇 |
物理学 | 43067篇 |
出版年
2022年 | 1413篇 |
2021年 | 1629篇 |
2020年 | 1806篇 |
2019年 | 1752篇 |
2018年 | 1874篇 |
2017年 | 1657篇 |
2016年 | 2699篇 |
2015年 | 2124篇 |
2014年 | 2993篇 |
2013年 | 5787篇 |
2012年 | 5895篇 |
2011年 | 6946篇 |
2010年 | 4698篇 |
2009年 | 4731篇 |
2008年 | 5563篇 |
2007年 | 5337篇 |
2006年 | 4945篇 |
2005年 | 4260篇 |
2004年 | 3768篇 |
2003年 | 3264篇 |
2002年 | 3128篇 |
2001年 | 4538篇 |
2000年 | 3394篇 |
1999年 | 2784篇 |
1998年 | 2128篇 |
1997年 | 2073篇 |
1996年 | 1941篇 |
1995年 | 1684篇 |
1994年 | 1545篇 |
1993年 | 1349篇 |
1992年 | 1710篇 |
1991年 | 1671篇 |
1990年 | 1489篇 |
1989年 | 1319篇 |
1988年 | 1294篇 |
1987年 | 1322篇 |
1986年 | 1135篇 |
1985年 | 1414篇 |
1984年 | 1366篇 |
1983年 | 951篇 |
1982年 | 977篇 |
1981年 | 927篇 |
1980年 | 823篇 |
1979年 | 1028篇 |
1978年 | 1035篇 |
1977年 | 1059篇 |
1976年 | 968篇 |
1975年 | 836篇 |
1974年 | 853篇 |
1973年 | 791篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
The Ramanujan Journal - Inspired by Andrews and Merca’s recent work on the number of even parts over all partitions into distinct parts, we introduce a new kind of Beck type identities, which... 相似文献
42.
Valiullina Z. R. Ivanova N. A. Shitikova O. V. Miftakhov M. S. 《Russian Journal of Organic Chemistry》2019,55(8):1131-1135
Russian Journal of Organic Chemistry - Methyl (Z)-3-[(2R,3R,4S,5S)-5-(2-methoxy-2-oxoethyl)-3,4-(isopropylidenedioxy)tetrahydrofuran-2-yl]-prop-2-enoate was synthesized, and its intramolecular... 相似文献
43.
Journal of Thermal Analysis and Calorimetry - A complete analysis of the thermal process about melamine was presented, in which different methods were applied to determine the characteristic of the... 相似文献
44.
45.
本文基于新的Kronecker型替换,给出两个由黑盒表示的稀疏多项式的新确定性插值算法.令f∈R[x1,……,xn]是一个稀疏黑盒多项式,其次数上界为D.当R是C或者是有限域时,相对于已有算法,新算法具有更好的计算复杂度或者关于D的复杂度更低.特别地,对于一般黑盒模型,D是复杂度中的主要因素,而在所有的确定性算法中,本文的第二个算法的复杂度关于D是最低的. 相似文献
46.
Saleh Z. M. Nasser H. Özkol E. Günöven M. Abak K. Canli S. Bek A. Turan R. 《Journal of nanoparticle research》2015,17(10):1-12
Journal of Nanoparticle Research - Plasmonic interfaces consisting of silver nanoparticles of different sizes (50–100&;nbsp;nm) have been processed by the self-assembled dewetting... 相似文献
47.
48.
Triazines are widely used in agriculture around the world as selective pre‐ and post‐emergence herbicides for the control of broad leaf and grassy weeds. With high toxicity and persistence, triazines can contaminate the environment and crops, so the development of rapid and sensitive methods for the determination of different triazines is necessary. Capillary electrophoresis comprises a group of techniques used to separate chemical mixtures. Analytical separation is based on different electrophoretic mobilities. This review focuses on the analysis of triazine herbicides with different modes of capillary electrophoresis, including capillary zone electrophoresis, micellar electrokinetic capillary electrophoresis, capillary electrochromatography and nonaqueous capillary electrophoresis. Determinations of triazines in various matrices such as surface water, groundwater, vegetables, soil and grains are emphasized. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
49.
50.
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