全文获取类型
收费全文 | 5634篇 |
免费 | 181篇 |
国内免费 | 11篇 |
专业分类
化学 | 3082篇 |
晶体学 | 100篇 |
力学 | 168篇 |
综合类 | 1篇 |
数学 | 1192篇 |
物理学 | 1283篇 |
出版年
2023年 | 39篇 |
2022年 | 55篇 |
2021年 | 92篇 |
2020年 | 112篇 |
2019年 | 134篇 |
2018年 | 199篇 |
2017年 | 196篇 |
2016年 | 261篇 |
2015年 | 191篇 |
2014年 | 243篇 |
2013年 | 620篇 |
2012年 | 386篇 |
2011年 | 393篇 |
2010年 | 310篇 |
2009年 | 243篇 |
2008年 | 283篇 |
2007年 | 260篇 |
2006年 | 158篇 |
2005年 | 115篇 |
2004年 | 123篇 |
2003年 | 116篇 |
2002年 | 94篇 |
2001年 | 86篇 |
2000年 | 64篇 |
1999年 | 50篇 |
1998年 | 55篇 |
1997年 | 48篇 |
1996年 | 42篇 |
1995年 | 35篇 |
1994年 | 43篇 |
1993年 | 28篇 |
1992年 | 35篇 |
1991年 | 23篇 |
1990年 | 33篇 |
1989年 | 40篇 |
1988年 | 31篇 |
1987年 | 21篇 |
1985年 | 37篇 |
1984年 | 41篇 |
1983年 | 29篇 |
1982年 | 26篇 |
1981年 | 22篇 |
1980年 | 28篇 |
1979年 | 34篇 |
1978年 | 34篇 |
1977年 | 28篇 |
1976年 | 36篇 |
1975年 | 21篇 |
1974年 | 34篇 |
1973年 | 21篇 |
排序方式: 共有5826条查询结果,搜索用时 31 毫秒
101.
M. Pavičić 《International Journal of Theoretical Physics》1993,32(9):1481-1505
It is shown that an orthomodular lattice is an ortholattice in which aunique operation of bi-implication corresponds to the equality relation and that the ordering relation in the binary formulation of quantum logic as well as the operation of implication (conditional) in quantum logic are completely irrelevant for their axiomatization. The soundness and completeness theorems for the corresponding algebraic unified quantum logic are proved. A proper semantics, i.e., a representation of quantum logic, is given by means of a new YES-NO relation which might enable a proof of the finite model property and the decidability of quantum logic. A statistical YES-NO physical interpretation of the quantum logical propositions is provided. 相似文献
102.
Y. A. Gordon V. Jakšić S. Molčanov B. Simon 《Communications in Mathematical Physics》1993,157(1):23-50
We investigate spectral properties of random Schrödinger operators H = - + n()(1 + |n|) acting onl
2(Z
d), where n are independent random variables uniformly distributed on [0, 1].Research partially supported by a Sloan Doctoral Dissertation Fellowship and NSERC under grant OGP-0007901Research partially supported by NSF grant DMS-9101716 相似文献
103.
α-Aspartame (L-α-aspartyl-L-phenylalanine methyl ester) is increasingly being used in wide variety of commonly consumed food products. This structure contains ester and peptide bonds. The ester linkage may hydrolyze to produce L-α-aspartyl-L-phenylalanine or cyclohydrolyze to produce the corresponding diketopiperazine ring. This ring can open to form L-α-aspartyl-L-phenylalanine and ultimately this compound can hydrolyze to L-phenylalanine and L-aspartic acid. The pH, buffer type, concentration, the presence of water and temperature are other important factors affecting its stability. Because α-aspartame can lose its sweetness under these conditions determination of aspartame and its breakdown products is extremely important for diet foods quality. The optimum mobile phase for the chromatographic separation was found to be acetonitrile-water (20:80, ν/ν) with 5.10?3 M hexanesulfonic acid and a pH of 2.6. 相似文献
104.
A. Baştuğ Ö. Söğüt Y. Şahin M. Ertuğrul 《Journal of Radioanalytical and Nuclear Chemistry》2002,251(2):323-327
La and Lb X-ray fluorescence cross sections in Er, Ta, W and Au at excitation energies of 16.896, 22.581, 25.770, 32.890, 38.184, 43.949, 50.214 and 59.5 keV were investigated. Measurements were made using a low energy Si(Li) detector coupled to a model 4096 computerized multi-channel analyser. The experimental results were compared with the theoretically calculated values of L X-rays fluorescence cross sections and other experimental results. Good agreement was observed between experimental and theoretical values. 相似文献
105.
H. Yücel H. Karadeniz M. A. Çetiner H. Demirel Ş. Turhan 《Journal of Radioanalytical and Nuclear Chemistry》2003,258(2):445-447
The sorption behavior of 235U fission fission products 99Mo and 132Te was studied through batch and dynamic experiments when they were dissolved in 1 to 7M HNO3 solutions. It was found that 99Mo is always totally adsorbed on hydrated SnO2, while 132Te is rather weakly adsorbed, therefore they can be separated from each other although 132Te in the solution still remains contaminated with other radionuclides as well as 99Mo does in the solid. 相似文献
106.
R.R. Adžić D.N. Simić A.R. Despić D.M. Dražić 《Journal of Electroanalytical Chemistry》1977,80(1):81-99
The catalytic effects of a submonolayer of lead on noble metals have been shown and discussed in terms of a previously published model. A theoretical analysis of these effects is presented. It was demonstrated that foreign metal monolayers allow a determination of the true catalytic activity of electrodes in the case of self-poisoning reactions. A volcano-shaped curve for oxidation of formic acid on noble metal electrodes was obtained. 相似文献
107.
Phosphorus is determined by inductively-coupled plasma atomic emission spectrometry at 213.618 nm. Different types of organic and inorganic phosphorus compounds and metal complexes were examined after direct dissolution in water, aqueous ethanol or acid, or after decomposition by oxygen flask combustion or Kjeldahl digestion; results were within the usual limit of precision and accuracy for such determinations. The effect of small (<20%) ethanol concentrations in the aqueous solution on the signals obtained from a low-power (1200 W) argon plasma is examined and discussed. 相似文献
108.
G. Erdogduğ 《Journal of Analytical Chemistry》2002,57(7):620-623
A gold electrode was modified with electropolymerized films of 4-methoxyphenol by its oxidative polymerization from an alkaline solution by cyclic voltammetry. The modified electrode was then used to determine epinephrine (EP) in the presence of a high concentration of ascorbic acid (AA) by differential pulse voltammetry. The peak positions as well as relative sensitivity EP/AA were affected by the potential window used for the polymerization. For polymerization between 0 and 1.3 V, the peak potentials recorded in a phosphate buffer solution (pH = 7.2) were 516 and 312 mV vs. Ag/AgCl for EP and AA, respectively. In addition the effects of pH and the type of electrolyte on the linearity range and detection limit are investigated. The detection limit for 3s-test is 0.1 M. The high selectivity and sensitivity for epinephrine was found to be due to charge discrimination/analyte accumulation. 相似文献
109.
The paper presents a survey of the contamination level of the Danube river sediments along its course, between 849 km and 1162 km, during the period 1985–1988. Sampling was performed on several locations in the seasons with extreme hydrological conditions (spring, autumn). 相似文献
110.
Nadica Ivošević DeNardis Vera Žutić Vesna Svetličić Ranieri Urbani 《Electroanalysis》2007,19(4):473-478
In situ amperometric characterization of an aggregating system in terms of molecular adsorption and single microparticle interactions at the electrode interface is demonstrated using a model system: alginate/Ca(II) in an aqueous electrolyte solution. Recording of chronoamperometric curves of oxygen reduction at the dropping mercury electrode is designed for detection of dip‐shaped signals of individual gel microparticles. By addition of Ca(II) decrease of alginate adsorption is accompanied by appearance of signals indicating vesicle type association of alginate molecules and microparticles of gel phase. AFM imaging provided evidence of initial stage in calcium alginate gel formation. 相似文献