全文获取类型
收费全文 | 24385篇 |
免费 | 65篇 |
国内免费 | 56篇 |
专业分类
化学 | 10139篇 |
晶体学 | 406篇 |
力学 | 962篇 |
综合类 | 11篇 |
数学 | 3711篇 |
物理学 | 9277篇 |
出版年
2023年 | 17篇 |
2022年 | 185篇 |
2021年 | 368篇 |
2020年 | 376篇 |
2019年 | 554篇 |
2018年 | 1015篇 |
2017年 | 1122篇 |
2016年 | 1335篇 |
2015年 | 547篇 |
2014年 | 1111篇 |
2013年 | 1682篇 |
2012年 | 1523篇 |
2011年 | 1577篇 |
2010年 | 1802篇 |
2009年 | 1736篇 |
2008年 | 1717篇 |
2007年 | 1633篇 |
2006年 | 1423篇 |
2005年 | 903篇 |
2004年 | 636篇 |
2003年 | 331篇 |
2002年 | 321篇 |
2001年 | 314篇 |
2000年 | 613篇 |
1999年 | 353篇 |
1998年 | 454篇 |
1997年 | 430篇 |
1996年 | 123篇 |
1995年 | 32篇 |
1994年 | 33篇 |
1993年 | 6篇 |
1992年 | 15篇 |
1991年 | 14篇 |
1990年 | 15篇 |
1989年 | 6篇 |
1988年 | 15篇 |
1987年 | 13篇 |
1986年 | 11篇 |
1985年 | 8篇 |
1984年 | 10篇 |
1983年 | 17篇 |
1982年 | 8篇 |
1981年 | 14篇 |
1980年 | 7篇 |
1978年 | 9篇 |
1977年 | 6篇 |
1974年 | 10篇 |
1971年 | 6篇 |
1970年 | 5篇 |
1968年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Complexation of antibiotics cefazolin and cefoperazone with the methylene blue thiazine dye was studied. Composition (1: 1),
stability constants (150±30 M
−1), and solubility of the complexes were determined. 相似文献
992.
A. G. Smol’nikov V. V. Ogloblichev S. V. Verkhovskii K. N. Mikhalev A. Yu. Yakubovskii K. Kumagai Y. Furukawa A. F. Sadykov Yu. V. Piskunov A. P. Gerashchenko S. N. Barilo S. V. Shiryaev 《JETP Letters》2015,102(10):674-677
The magnetically ordered phase of the CuCrO2 single crystal has been studied by the nuclear magnetic resonance (NMR) method on 53Cr nuclei in the absence of an external magnetic field. The 53Cr NMR spectrum is observed in the frequency range νres = 61–66 MHz. The shape of the spectrum depends on the delay tdel between pulses in the pulse sequence τπ/2–t del–τπ–t del–echo. The spin–spin and spin–lattice relaxation times have been measured. Components of the electric field gradient, hyperfine fields, and the magnetic moment on chromium atoms have been estimated. 相似文献
993.
994.
995.
996.
Soft robots are bio-inspired, highly deformable robots with the ability to interact with workpieces in a manner that complements their hard robot counterparts. To develop practical applications and reproducible designs of soft robots, new models are necessary to describe their kinematics and dynamics. In the present work, we describe experimental and numerical investigations of a popular pneumatically-actuated soft continuum arm. These works enable us to derive constitutive relations and develop a rod model for large deformations of the arm that faithfully describes its bending behavior. We show how the resulting non-classical constitutive relation can be defined either through experiments or through quasi-static finite element simulations. With the help of this relation, the resulting rod model can be used to study the dynamics of the soft robot arm in a fast and tractable manner. (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
997.
Valeriya A. Startseva Olga A. Lodochnikova Alexander E. Klimovitskii Alexander V. Aref’ev Nadezhda P. Artemova 《Phosphorus, sulfur, and silicon and the related elements》2013,188(5):615-629
Abstract The oxidation of a β-hydroxysulfide in the pinane series by use of m-chloroperbenzoic acid resulted in the formation of the corresponding β-hydroxysulfoxide as a mixture of two diastereomers in 4:5 ratio. According to single-crystal X-ray diffraction (XRD) results, it is established that the diastereomeric mixture of sulfoxides crystallizes in the “racemic compound-like” manner under formation of asymmetric dimers through S=O··H–O interactions. This asymmetric dimer formed from diastereomeric molecules is a structural unit in both crystal modifications, the triclinic and the monoclinic one. The behavior of the diastereomeric mixture of pinane derived sulfoxides in crystals, melts and in tetrachloromethane solutions was studied by IR spectroscopy. The density functional theory (DFT) method with 6-31G (d, p) basis set was used to calculate the optimized geometrical parameters and vibrational frequencies of different associates in solutions. The calculated vibrational frequencies are compared with experimental IR spectra. 相似文献
998.
Svetlana F. Malysheva Natal’ya A. Belogorlova Nina K. Gusarova Alexander V. Artem’ev Alexander I. Albanov Boris A. Trofimov 《Phosphorus, sulfur, and silicon and the related elements》2013,188(8):1688-1693
Abstract Red phosphorus reacts with allylbenzene in the superbase system KOH-DMSO (130°C, 3 h, Ar) to give a mixture of bis(1-methyl-2-phenylethyl)phosphane (1), bis(1-methyl-2-phenylethyl)phosphane oxide (2), and 1-methyl-2-phenylethylphosphinic acid (3). Secondary phosphane oxide 2 and phosphinic acid 3 have been isolated from this mixture in 35% and 32% yield, respectively. Microwave activation of the reaction (200 W, 30 min) affords secondary phosphane 1 as the main product in 48% yield. GRAPHICAL ABSTRACT 相似文献
999.
Il’yas S. Nizamov Ilnar D. Nizamov Farid D. Yambushev Olga V. Bolshakova Gulnur G. Sergeenko Vladimir F. Mironov 《Phosphorus, sulfur, and silicon and the related elements》2013,188(7):1436-1442
Abstract The reactions of geraniol, nerol, and linalool with N,N-diethylamido O,O-propylenephosphite and diethyl chlorophosphite were studied. On the basis of these studies, new dienyl diprenoid phosphite esters were obtained. GRAPHICAL ABSTRACT 相似文献
1000.
A. A. Kaunova V. I. Petrov T. G. Tsyupko Z. A. Temerdashev V. V. Perekotii A. A. Luk’yanov 《Journal of Analytical Chemistry》2013,68(9):831-836
We have estimated the possibility of identifying the provenance of some natural wines produced in the Krasnodar region. The macro- and microelement composition of wines and soils from the place of grape origin has been used as the classification criterion. The main elements indicating the wine provenance, Al, Co, Cu, Mn, Ti, Zn, Ba, and Rb have been determined by inductively coupled plasma atomic emission spectroscopy. We have revealed the possibility of distinguishing wines by their brand and provenance using pair-wise comparison of the classification function parameters for soils and wines produced from grape grown on those soils. 相似文献