全文获取类型
收费全文 | 845篇 |
免费 | 16篇 |
专业分类
化学 | 655篇 |
晶体学 | 1篇 |
力学 | 5篇 |
数学 | 55篇 |
物理学 | 145篇 |
出版年
2023年 | 3篇 |
2022年 | 7篇 |
2021年 | 6篇 |
2020年 | 11篇 |
2019年 | 5篇 |
2018年 | 15篇 |
2017年 | 14篇 |
2016年 | 38篇 |
2015年 | 43篇 |
2014年 | 33篇 |
2013年 | 72篇 |
2012年 | 46篇 |
2011年 | 86篇 |
2010年 | 70篇 |
2009年 | 57篇 |
2008年 | 44篇 |
2007年 | 15篇 |
2006年 | 44篇 |
2005年 | 20篇 |
2004年 | 13篇 |
2003年 | 15篇 |
2002年 | 21篇 |
2001年 | 9篇 |
2000年 | 8篇 |
1999年 | 19篇 |
1998年 | 7篇 |
1997年 | 10篇 |
1996年 | 11篇 |
1994年 | 6篇 |
1992年 | 7篇 |
1991年 | 6篇 |
1990年 | 4篇 |
1989年 | 4篇 |
1988年 | 6篇 |
1987年 | 8篇 |
1986年 | 8篇 |
1985年 | 4篇 |
1984年 | 8篇 |
1983年 | 3篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1978年 | 4篇 |
1977年 | 5篇 |
1976年 | 5篇 |
1975年 | 4篇 |
1974年 | 3篇 |
1973年 | 5篇 |
1968年 | 4篇 |
1956年 | 2篇 |
排序方式: 共有861条查询结果,搜索用时 15 毫秒
91.
J. Klusoň 《The European Physical Journal C - Particles and Fields》2011,71(12):1820
We consider RFDiff invariant Hořava–Lifshitz gravity action with additional Lagrange multiplier term that is a function of
scalar curvature. We find its Hamiltonian formulation and we show that the constraint structure implies the same number of
physical degrees of freedom as in General Relativity. 相似文献
92.
Kateřina Staňková Helisová Jakub Staněk 《Methodology and Computing in Applied Probability》2014,16(2):355-368
Many objects studied in biology, medicine or material sciences create spatial formations of random shape in which we can observe mutual interactions among those objects. In order to analyse the data composed of such patterns, we use the methods of spatial statistics. Recently, extended random-disc Quermass-interaction process was studied, simulated and consequently statistically analysed using MCMC maximum likelihood method (MCMC MLE). However, this analysis brought some problems. First, it was quite time-consuming, secondly, in some special cases, the parameter estimates may undervalue the real parameter values. In this paper, we describe how we can solve these problems by dimension reduction. 相似文献
93.
94.
95.
Boris Remenec Silvia Dulanská Veronika Gardoňová Ľubomír Mátel 《Journal of Radioanalytical and Nuclear Chemistry》2013,295(2):907-910
This paper describes a rapid method of 94Nb pre-concentration, separation and purification by using cation and anion exchange resins. The method is suitable for analyzing highly contaminated radioactive waste samples in a relatively short time and high decontamination factors. The use and effectiveness of the method was successfully tested by analysis of samples from nuclear reactor parts such as control rod drive shaft, shielding cassettes, neutron in-core measurement channels (KNI), pressure vessel construction material and fuel cassette construction material samples. 相似文献
96.
Jan Turek Zdeňka Růžičková Eva Tloušťová Helena Mertlíková‐Kaiserová Jana Günterová Lubomír Rulíšek Aleš Růžička 《应用有机金属化学》2016,30(5):318-322
Two gold(I) complexes of the (NHC)AuX type bearing a triazole‐based N‐heterocyclic carbene (NHC) ligand (1‐tert‐butyl‐4‐(4‐methylphenyl)‐3‐phenyl‐1H‐1,2,4‐triazol‐4‐ium‐5‐ylidene) and various halide ligands (X = Br, I) were synthesized and characterized in solution using NMR spectroscopy as well as in the solid state using X‐ray diffraction techniques. The cytotoxic properties of both compounds and the precursor, (NHC)AuCl, were screened against a panel of human tumour cell lines including liver cancer (HepG2), cervical cancer (HeLa S3) and leukaemia (CCRF‐CEM, HL‐60) and compared to cisplatin and auranofin. It was found that the activities of the chloro and bromo derivatives were generally superior to that of cisplatin and slightly less effective compared to auranofin, except for HepG2 cells where auranofin was not as effective. In addition, the ability to induce membrane phosphatidyl serine externalization as a hallmark of apoptosis in CCRF‐CEM leukaemic cells was investigated. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
97.
98.
Hausdorff momentum problem and its relations to spectral theorem for bounded Hilbert space operators are treated. A generalization for some ordered algebras is shown, where projections are replaced by idempotents. 相似文献
99.
Andrej Oriňák Renáta Oriňáková Guido Vering Valdir Cechinel-Filho 《Applied Surface Science》2006,252(19):6668-6671
Microcolumn liquid chromatography (μHPLC) coupled on-line with time of flight secondary ion mass spectrometry (ToF-SIMS) was applied for mixture of diterpenoic acids (abietic, gibberellic and kaurenoic) analysis. Chromatographic effluent, with analytes separated, was carried out directly onto different, ToF-SIMS compatible surface substrates, for further ToF-SIMS analysis. Silica gel Si60, aluminium backplate modified Si60, monolithic silica gel and Raman spectroscopy chromatographic thin layers were used as the deposition substrates in this experiment. By ToF-SIMS surface imaging the deposition trace picture has been obtained. Effluent deposition surface area was scanned for diterpenoic acid fragment mass values based on mass spectrometric library. Measured ToF-SIMS dataset of fragment abundance and intensities were used for preliminary fragmentation schemes construction. The lowest substrate background activity has been established for monolithic silica gel thin layer and aluminium backplate modified Si60 thin layer. In the case of Raman spectroscopy pre-treated thin layer or conventional chromatographic thin layer Si60, the both, high background signal intensity and impossibility to construct negative ions surface image, were observed. Diterpenoic acids studied serve the similar mass spectrum but ToF-SIMS coupled with liquid chromatographic separation brings new impact to the positive identification of analytes studied. 相似文献
100.
Electrochemical Activity of Wedelolactone and Probing its Interaction with DNA Using Voltammetry at a Carbon Electrode 下载免费PDF全文
Wedelolactone (WLA) is a polyphenolic coumestan derivative found in extracts of plants used in traditional medicine. Due to its cytostatic activity, WLA is one of natural compounds tested as potential anticancer drugs. In this work we for the first time studied electrochemical properties of WLA using cyclic (CV) and square‐wave (SWV) voltammetry at the basal‐plane pyrolytic graphite electrode. A reversible pair of peaks, corresponding to catechol/o‐benzoquinone redox system, was observed using CV around 0.275 V vs. Ag|AgCl|3 M KCl reference electrode. Measurements of SWV signal of WLA in the presence of single‐ or double‐stranded DNA suggested a weak interaction without evident preference for double‐stranded DNA. An indirect assay, employing electroactive DNA intercalator doxorubicin as competitor, confirmed absence of intercalative DNA binding of WLA. 相似文献