全文获取类型
收费全文 | 353篇 |
免费 | 17篇 |
国内免费 | 1篇 |
专业分类
化学 | 269篇 |
晶体学 | 4篇 |
力学 | 3篇 |
数学 | 44篇 |
物理学 | 51篇 |
出版年
2023年 | 11篇 |
2022年 | 11篇 |
2021年 | 9篇 |
2020年 | 12篇 |
2019年 | 15篇 |
2018年 | 6篇 |
2017年 | 5篇 |
2016年 | 18篇 |
2015年 | 11篇 |
2014年 | 11篇 |
2013年 | 16篇 |
2012年 | 22篇 |
2011年 | 21篇 |
2010年 | 14篇 |
2009年 | 15篇 |
2008年 | 15篇 |
2007年 | 10篇 |
2006年 | 27篇 |
2005年 | 12篇 |
2004年 | 11篇 |
2003年 | 13篇 |
2002年 | 11篇 |
2001年 | 5篇 |
2000年 | 4篇 |
1999年 | 2篇 |
1998年 | 5篇 |
1997年 | 3篇 |
1996年 | 5篇 |
1995年 | 3篇 |
1994年 | 2篇 |
1990年 | 4篇 |
1989年 | 1篇 |
1988年 | 5篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1984年 | 4篇 |
1981年 | 3篇 |
1980年 | 1篇 |
1979年 | 3篇 |
1978年 | 4篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1955年 | 1篇 |
1954年 | 1篇 |
1948年 | 1篇 |
1933年 | 2篇 |
1910年 | 2篇 |
排序方式: 共有371条查询结果,搜索用时 31 毫秒
81.
Spezia S Bocca B Forte G Gatti A Mincione G Ronchi A Bavazzano P Alimonti A Minoia C 《Rapid communications in mass spectrometry : RCM》2005,19(11):1551-1556
In recent years the increasing use of platinum (Pt) both in medical and in industrial applications has caused its growing anthropogenic emission and spread in the environment. Pt is released into the atmosphere by exhaust catalytic converters, and Pt compounds are often used in antitumour therapies. As a consequence, significant amounts of Pt can be detected in hospital wastewaters. This can lead to an increase in the exposure levels to Pt, especially in urban areas. It is therefore necessary to determine Pt reference values in the general population, by using suitable procedures able to achieve adequate analytical performances. Several measurements of Pt in biological fluids have been reported, but the analytical methods used for the determination of Pt often lack information about the uncertainty of the results, especially for low concentrations of urinary Pt in non-occupationally exposed subjects. The present paper considers the measurement of urinary Pt levels in a general population group from central Italy, by both quadrupole (Q) and sector field (SF) inductively coupled plasma mass spectrometry (ICP-MS). The two procedures were validated and their expanded uncertainties were evaluated. The limits of detection (LODs), calculated taking into account dilution factors, were 0.18 and 0.05 ng L(-1) of Pt for the Q and SF procedures, respectively. The median value observed was 4.13 ng L(-1) of Pt in urine, while the relative combined uncertainty at 5 ng L(-1) was below 20% with both ICP-MS techniques. These data are in good agreement with those reported in the literature for similar studies. 相似文献
82.
83.
The coupling of two locally mass conservative methods is formulated and analyzed for the time‐dependent convection‐diffusion problem. Finite volume method is used in some subdomains and interior penalty discontinuous Galerkin method is used in other subdomains. Numerical examples show the advantages of the proposed hybrid method, namely an accurate approximation obtained at a reduced computational cost. © 2013 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 30: 133–157, 2014 相似文献
84.
85.
86.
A. Wutzler H.-J. Radusch K. Gehrmann 《Journal of Macromolecular Science: Physics》2013,52(5-6):1095-1099
The diffusion of acetophenone in peroxide cross-linked low-density polyethylene (LDPE) medium-voltage cable was investigated with Fourier transform infrared (FTIR) microscopy. The influence of storage under normal climate and for up to 2 years on the acetophenone profile are discussed. The diffusion rate and the coefficient of diffusion of acetophenone in cross-linked LDPE were determined. It could be shown that the coefficient of diffusion is independent of the morphology of the medium-voltage cables investigated. 相似文献
87.
Beatrice Nicolaï P. Espeau R. Céolin M. -A. Perrin L. Zaske J. Giovannini F. Leveiller 《Journal of Thermal Analysis and Calorimetry》2007,90(2):337-339
Spironolactone (C24H32O4S) usually crystallizes into an orthorhombic phase, named Form II. Another orthorhombic phase, named Form I, is also known
but seems difficult to obtain. Studies of the kinetics of desolvation of the ethanol solvate at room temperature showed that
these two forms can be obtained through different mechanisms of desolvation. 相似文献
88.
α-Well-posedness for Nash Equilibria and For Optimization Problems with Nash Equilibrium Constraints
We present the concepts of α-well-posedness for parametric noncooperative games and for optimization problems with constraints defined by parametric Nash equilibria. We investigate some classes of functions that ensure these types of well-posedness and the connections with α-well-posedness for variational inequalities and optimization problems with variational inequality constraints. 相似文献
89.
Beatrice Bartolomei Giuseppe Gentile Dr. Cristian Rosso Dr. Giacomo Filippini Prof. Maurizio Prato 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(65):16062-16070
Phenols ( I ) are extremely relevant chemical functionalities in natural, synthetic and industrial chemistry. Their corresponding electron-rich anions, namely phenolates ( I ), are characterized by interesting physicochemical properties that can be drastically altered upon light excitation. Specifically, phenolates ( I ) become strong reducing agents in the excited state and are able to generate reactive radicals from suitable precursors via single-electron transfer processes. Thus, these species can photochemically trigger strategic bond-forming reactions, including their direct aromatic C−H functionalization. Moreover, substituted phenolate anions can act as photocatalysts to enable synthetically useful organic transformations. An alternative mechanistic manifold is represented by the ability of phenolate derivatives I to form ground state electron donor-acceptor (EDA) complexes with electron-poor radical sources. These complementary scenarios have paved the way for the development of a wide range of relevant organic reactions. In this Minireview, we present the main examples of this research field, and give insight on emerging trends in phenols photocatalysis towards richer organic synthesis. 相似文献
90.