全文获取类型
收费全文 | 2397篇 |
免费 | 187篇 |
国内免费 | 5篇 |
专业分类
化学 | 1667篇 |
晶体学 | 46篇 |
力学 | 66篇 |
数学 | 394篇 |
物理学 | 416篇 |
出版年
2023年 | 37篇 |
2022年 | 29篇 |
2021年 | 57篇 |
2020年 | 117篇 |
2019年 | 79篇 |
2018年 | 49篇 |
2017年 | 52篇 |
2016年 | 137篇 |
2015年 | 101篇 |
2014年 | 107篇 |
2013年 | 129篇 |
2012年 | 148篇 |
2011年 | 162篇 |
2010年 | 90篇 |
2009年 | 77篇 |
2008年 | 106篇 |
2007年 | 89篇 |
2006年 | 65篇 |
2005年 | 59篇 |
2004年 | 36篇 |
2003年 | 50篇 |
2002年 | 44篇 |
2001年 | 21篇 |
2000年 | 23篇 |
1999年 | 22篇 |
1998年 | 21篇 |
1997年 | 16篇 |
1996年 | 16篇 |
1995年 | 22篇 |
1994年 | 15篇 |
1991年 | 19篇 |
1989年 | 23篇 |
1988年 | 17篇 |
1987年 | 16篇 |
1986年 | 21篇 |
1985年 | 13篇 |
1984年 | 27篇 |
1983年 | 16篇 |
1981年 | 20篇 |
1980年 | 20篇 |
1979年 | 14篇 |
1978年 | 10篇 |
1977年 | 12篇 |
1976年 | 18篇 |
1974年 | 17篇 |
1972年 | 11篇 |
1971年 | 10篇 |
1968年 | 10篇 |
1967年 | 14篇 |
1930年 | 9篇 |
排序方式: 共有2589条查询结果,搜索用时 15 毫秒
41.
42.
Gerhard Schulze Edzard Han Wolfgang Frenzel 《Fresenius' Journal of Analytical Chemistry》1989,332(8):844-848
Summary The interferences caused by inorganic ions, organic anions and Triton X-100 in the determination of lead by flow injection potentiometric and voltammetric stripping analysis at a mercury film electrode were investigated. The experiments were performed in the concentration range of 1–10 mg/l Pb2+. For both methods linear calibration plots were obtained in the presence of an excess of nitrate, chloride, perchlorate and sulphate. Iodide strongly interferes due to mercury complexation.Metal ion interference caused by formation of irreversible amalgams (as in the case of codeposition of Ni, Co, Fe and Cr) is avoided by proper choice of deposition potential. No effect of water soluble reduced species, i.e. Fe(II) and Cr(II), on the stripping signals was observed. The presence of acetate, citrate and tartrate does not limit the determination of lead by potentiometric stripping analysis (PSA) but has a marked effect on anodic stripping voltammetric (ASV) signals. No influence of Triton X-100 on the determination of lead by PSA was found. In ASV 10–3% Triton X-100 diminished the peak current by 15%.
Herrn Prof. Dr. Rolf Neeb aus Anlaß seines 60. Geburtstags gewidmet 相似文献
Herrn Prof. Dr. Rolf Neeb aus Anlaß seines 60. Geburtstags gewidmet 相似文献
43.
High-modulus carbon fibers are used as working electrodes in differential-pulse stripping voltammetry and potentiometric stripping analysis. Different types of electrodes (particularly single-fiber and brush electrodes) are compared with regard to reproducibility, sensitivity, and practical aspects. Zinc, cadmium, and lead are determined in the 100 μg 1?1 to 1 mg l?1 range and optimum experimental parameters are described. The cut single-fiber electrode has the best general characteristics. 相似文献
44.
45.
Iwan Jerjen Vincent Revol Andreas J. Brunner Philipp Schuetz Christian Kottler Rolf Kaufmann Thomas Luethi Giovanni Nicoletti Claus Urban Urs Sennhauser 《Polymer Testing》2013
The processing of thermoplastics can induce a wide range of defects such as stress whitening, cavitation and porosity, which can adversely affect the reliability of the final products. Hence, fast and effective non-destructive detection methods for such defects are highly important for quality assurance on production lines. In this paper, X-ray dark field imaging is presented as a new non-destructive testing method that allows the visualization of stress whitening or cavitation efficiently. The performance of the method is demonstrated for the case of an injection-moulded polyvinylidene fluoride part that exhibits stress whitening. Whereas the stress whitening could not be detected by conventional X-ray imaging, it was localized by an X-ray dark field image acquired within a few minutes. Once the precise location of the stress whitening was known, it was possible to verify the result by local micro X-ray computed tomography and by a micro section image. 相似文献
46.
We present a simple method for determining the shape of fundamental domains of generalized modular groups related to Weyl groups of hyperbolic Kac?CMoody algebras. These domains are given as subsets of certain generalized upper half planes, on which the Weyl groups act via generalized modular transformations. Our construction only requires the Cartan matrix of the underlying finite-dimensional Lie algebra and the associated Coxeter labels as input information. We present a simple formula for determining the volume of these fundamental domains. This allows us to re-produce in a simple manner the known values for these volumes previously obtained by other methods. 相似文献
47.
U. Schulze M. Arndt F. Freidanck I. Beulich G. Pompe E. Meyer 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(7):1037-1044
Abstract The microstructure of ethylene copolymers based on 1-hexene, 1-octene, and norbornene as comonomers was studied and related to its melting, crystallization, and glass transition behavior as well as to tensile strength. 相似文献
48.
49.
Ingolf Kahle Stefan Krause Cornelius Krasselt Alexander Jakob Alexander Oehlke Colin Georgi Steffen Schulze Heinrich Lang Michael Hietschold Stefan Spange Christian von Borczyskowski 《Applied Physics A: Materials Science & Processing》2014,115(2):617-625
Optical properties of nanomaterials such as semiconductor and metal quantum dots are important for sensors and photovoltaic applications. We report on optical, microscopic, and AFM investigations on bulk and single nanoobjects such as metal and semiconducting nanoparticles. Firstly, of special interest is the investigation of Ag metal nanoaggregates formed in zeolites. Here, the defined structure of the zeolite serves both as size directing and a stabilizing agent. The size selected Ag aggregates fluoresce in the zeolite cages even after storage under ambient conditions for almost one year. In addition, single Ag particles escape the cages and can be investigated by fluorescence microscopy also with respect to sensor applications. Secondly, with respect to photovoltaic applications, energy transfer among organic dye molecules and semiconductor quantum dots is of great importance. We report on the extension of the optical absorption of ZnSe quantum dots into the UV regime and investigate excitation energy transfer within self-assembled nanoaggregates of surface functionalized QDs and fluorescent styrylpyridine dyes. 相似文献