全文获取类型
收费全文 | 6009篇 |
免费 | 238篇 |
国内免费 | 38篇 |
专业分类
化学 | 4250篇 |
晶体学 | 30篇 |
力学 | 175篇 |
综合类 | 1篇 |
数学 | 989篇 |
物理学 | 840篇 |
出版年
2024年 | 11篇 |
2023年 | 59篇 |
2022年 | 137篇 |
2021年 | 181篇 |
2020年 | 158篇 |
2019年 | 159篇 |
2018年 | 118篇 |
2017年 | 115篇 |
2016年 | 254篇 |
2015年 | 189篇 |
2014年 | 212篇 |
2013年 | 306篇 |
2012年 | 427篇 |
2011年 | 497篇 |
2010年 | 290篇 |
2009年 | 238篇 |
2008年 | 362篇 |
2007年 | 357篇 |
2006年 | 316篇 |
2005年 | 326篇 |
2004年 | 276篇 |
2003年 | 175篇 |
2002年 | 168篇 |
2001年 | 81篇 |
2000年 | 58篇 |
1999年 | 68篇 |
1998年 | 46篇 |
1997年 | 53篇 |
1996年 | 64篇 |
1995年 | 55篇 |
1994年 | 41篇 |
1993年 | 42篇 |
1992年 | 30篇 |
1991年 | 37篇 |
1990年 | 26篇 |
1989年 | 25篇 |
1988年 | 23篇 |
1987年 | 19篇 |
1986年 | 35篇 |
1985年 | 31篇 |
1984年 | 30篇 |
1983年 | 19篇 |
1982年 | 31篇 |
1981年 | 16篇 |
1980年 | 12篇 |
1979年 | 13篇 |
1978年 | 10篇 |
1976年 | 19篇 |
1975年 | 7篇 |
1973年 | 13篇 |
排序方式: 共有6285条查询结果,搜索用时 15 毫秒
1.
2.
Spyridon Koutsoukos Frederik Philippi Francisco Malaret Tom Welton 《Chemical science》2021,12(20):6820
There are thousands of papers published every year investigating the properties and possible applications of ionic liquids. Industrial use of these exceptional fluids requires adequate understanding of their physical properties, in order to create the ionic liquid that will optimally suit the application. Computational property prediction arose from the urgent need to minimise the time and cost that would be required to experimentally test different combinations of ions. This review discusses the use of machine learning algorithms as property prediction tools for ionic liquids (either as standalone methods or in conjunction with molecular dynamics simulations), presents common problems of training datasets and proposes ways that could lead to more accurate and efficient models.In this review article, the authors discuss the use of machine learning algorithms as tools for the prediction of physical and chemical properties of ionic liquids. 相似文献
3.
4.
Martin Kellert Jan-Simon Jeshua Friedrichs Nadine Anke Ullrich Alexander Feinhals Jonas Tepper Peter Lnnecke Evamarie Hey-Hawkins 《Molecules (Basel, Switzerland)》2021,26(7)
The development of novel, tumor-selective and boron-rich compounds as potential agents for use in boron neutron capture therapy (BNCT) represents a very important field in cancer treatment by radiation therapy. Here, we report the design and synthesis of two promising compounds that combine meta-carborane, a water-soluble monosaccharide and a linking unit, namely glycine or ethylenediamine, for facile coupling with various tumor-selective biomolecules bearing a free amino or carboxylic acid group. In this work, coupling experiments with two selected biomolecules, a coumarin derivative and folic acid, were included. The task of every component in this approach was carefully chosen: the carborane moiety supplies ten boron atoms, which is a tenfold increase in boron content compared to the l-boronophenylalanine (l-BPA) presently used in BNCT; the sugar moiety compensates for the hydrophobic character of the carborane; the linking unit, depending on the chosen biomolecule, acts as the connection between the tumor-selective component and the boron-rich moiety; and the respective tumor-selective biomolecule provides the necessary selectivity. This approach makes it possible to develop a modular and feasible strategy for the synthesis of readily obtainable boron-rich agents with optimized properties for potential applications in BNCT. 相似文献
5.
Karen Beatriz Méndez-Rodríguez Nicté Figueroa-Vega César Arturo Ilizaliturri-Hernandez Mónica Cardona-Alvarado Jaime Antonio Borjas-García Carlos Kornhauser Juan Manuel Malacara Rogelio Flores-Ramírez Francisco Javier Pérez-Vázquez 《Biomedical chromatography : BMC》2020,34(12):e4956
Metabolomics is a potential tool for the discovery of new biomarkers in the early diagnosis of diseases. An ultra-fast gas chromatography system equipped to an electronic nose detector (FGC eNose) was used to identify the metabolomic profile of Volatile Organic Compounds (VOCs) in type 2 diabetes (T2D) urine from Mexican population. A cross-sectional, comparative, and clinical study with translational approach was performed. We recruited twenty T2D patients and twenty-one healthy subjects. Urine samples were taken and analyzed by FGC eNose. Eighty-eight compounds were identified through Kovats's indexes. A natural variation of 30% between the metabolites, expressed by study groups, was observed in Principal Component 1 and 2 with a significant difference (p < 0.001). The model, performed through a Canonical Analysis of Principal coordinated (CAP), allowed a correct classification of 84.6% between healthy and T2D patients, with a 15.4% error. The metabolites 2-propenal, 2-propanol, butane- 2,3-dione and 2-methylpropanal, were increased in patients with T2D, and they were strongly correlated with discrimination between clinically healthy people and T2D patients. This study identified metabolites in urine through FGC eNose that can be used as biomarkers in the identification of T2D patients. However, more studies are needed for its implementation in clinical practice. 相似文献
6.
Brandão Pedro Francisco Ramos Rui Miguel Rodrigues José António 《Analytical and bioanalytical chemistry》2018,410(26):6873-6880
Analytical and Bioanalytical Chemistry - Formaldehyde is often applied in the industrial production of different products, such as textiles, insulation materials, or cosmetics, due to its... 相似文献
7.
8.
Vladimir A. Borovikov Francisco Javier Mendoza 《Journal of Fourier Analysis and Applications》2002,8(4):399-406
We study the pointwise convergence problem for the inverse Fourier transform of piecewise smooth functions, i.e., whether SrD f (\bx) ? f (\bx)S_{\rho D} f (\bx) \to f (\bx) as r? ¥\rho \to \infty . r? ¥\rho \to \infty . Here for \bx,\bxi ? \Rn\bx,\bxi \in \Rn SrDf(\bmx)=\dsf1(2p)n/2\intlirD [^(f)](\bxi) e\dst iá\bmx,\bxi? d\bxi . S_{\rho D}f(\bm{x})=\dsf1{(2\pi)^{n/2}}\intli_{\rho D} \widehat{f}(\bxi) e^{\dst i\langle\bm{x},\bxi\rangle} d\bxi~. is the partial sum operator using a convex and open set DD containing the origin, and rD={ r\bxi:\bxi ? D }\rho D=\left\{ \rho \bxi:\bxi\in D \right\}. 相似文献
9.
F. F. Maia Jr. J. A. K. Freire G. A. Farias V. N. Freire E. F. da Silva Jr. 《Applied Surface Science》2002,190(1-4):247-251
The excitonic properties of a ZnSe/ZnSxSe1−x strained quantum well (QW) are calculated taking into account interface effects. Numerical results obtained with ZnS0.18Se0.82/ZnSe QWs show that graded interfaces can be responsible for a strong broadening of excitonic spectra. 相似文献
10.