全文获取类型
收费全文 | 2924篇 |
免费 | 45篇 |
国内免费 | 7篇 |
专业分类
化学 | 2084篇 |
晶体学 | 20篇 |
力学 | 21篇 |
数学 | 364篇 |
物理学 | 487篇 |
出版年
2021年 | 28篇 |
2019年 | 34篇 |
2017年 | 24篇 |
2016年 | 40篇 |
2015年 | 43篇 |
2014年 | 53篇 |
2013年 | 70篇 |
2012年 | 90篇 |
2011年 | 105篇 |
2010年 | 78篇 |
2009年 | 65篇 |
2008年 | 99篇 |
2007年 | 90篇 |
2006年 | 117篇 |
2005年 | 87篇 |
2004年 | 77篇 |
2003年 | 71篇 |
2002年 | 91篇 |
2001年 | 50篇 |
2000年 | 50篇 |
1999年 | 50篇 |
1998年 | 50篇 |
1997年 | 48篇 |
1996年 | 47篇 |
1995年 | 63篇 |
1994年 | 57篇 |
1993年 | 38篇 |
1992年 | 43篇 |
1991年 | 43篇 |
1990年 | 38篇 |
1989年 | 33篇 |
1988年 | 41篇 |
1987年 | 38篇 |
1986年 | 43篇 |
1985年 | 51篇 |
1984年 | 51篇 |
1983年 | 24篇 |
1982年 | 37篇 |
1981年 | 46篇 |
1980年 | 50篇 |
1979年 | 39篇 |
1978年 | 56篇 |
1977年 | 46篇 |
1976年 | 51篇 |
1975年 | 49篇 |
1974年 | 62篇 |
1973年 | 60篇 |
1972年 | 35篇 |
1971年 | 22篇 |
1970年 | 34篇 |
排序方式: 共有2976条查询结果,搜索用时 2 毫秒
991.
Armin T. Exner Ida Pavlichenko Daniela Baierl Morten Schmidt Gerald Derondeau Bettina V. Lotsch Paolo Lugli Giuseppe Scarpa 《Laser \u0026amp; Photonics Reviews》2014,8(5):726-733
An innovative integrated sensing platform for the detection of various chemical analytes via translating the photonic stop‐band shift of a one‐dimensional photonic crystal (PC) into an electrical current change is proposed. The miniaturized sensing platform features an organic light‐emitting diode (OLED) as a light source and an organic photodetector (OPD) as a light sensor and allows for the detection of ethanol vapor concentrations down to ≈ 10 parts per million (ppm) in nitrogen, which corresponds to a stop‐band shift of ≈ 27 pm. The resolution of the proposed platform exceeds the capabilities of most commercial spectrometers and by far the human eye, while, at the same time, such a sensor is less expensive and less power consuming than a spectrometer. The presented setup is generic and can detect optical changes in the transmission of PCs, which can be induced by both vapor adsorption or by a liquid analyte, as demonstrated with a microfluidic setup. 相似文献
992.
David Borwein Jonathan M. Borwein Armin Straub 《Journal of Mathematical Analysis and Applications》2014
Wigner limits are given formally as the difference between a lattice sum, associated to a positive definite quadratic form, and a corresponding multiple integral. To define these limits, which arose in work of Wigner on the energy of static electron lattices, in a mathematically rigorous way one commonly truncates the lattice sum and the corresponding integral and takes the limit along expanding hypercubes or other regular geometric shapes. We generalize the known mathematically rigorous two- and three-dimensional results regarding Wigner limits, as laid down in [3], to integer lattices of arbitrary dimension. In doing so, we also resolve a problem posed in [6, Chapter 7]. For the sake of clarity, we begin by considering the simpler case of cubic lattice sums first, before treating the case of arbitrary quadratic forms. We also consider limits taken along expanding hyperballs with respect to general norms, and connect with classical topics such as Gauss's circle problem. Appendix A is included to recall certain properties of Epstein zeta functions that are either used in the paper or serve to provide perspective. 相似文献
993.
Marina Schenk Sydnie Lieb Henning Vieker Dr. André Beyer Prof. Dr. Armin Gölzhäuser Prof. Hai Wang Prof. Dr. Katharina Kohse‐Höinghaus 《Chemphyschem》2013,14(14):3248-3254
For the first time, nascent soot particles are probed by using helium‐ion microscopy (HIM). HIM is a technique that is similar to scanning electron microscopy (SEM) but it can achieve higher contrast and improved surface sensitivity, especially for carbonaceous materials. The HIM microscope yields images with a high contrast, which allows for the unambiguous recognition of smaller nascent soot particles than those observed in previous transmission electron microscopy studies. The results indicate that HIM is ideal for rapid and reliable probing of the morphology of nascent soot, with surface details visible down to approximately 5 nm, and particles as small as 2 nm are detectable. The results also show that nascent soot is structurally and chemically inhomogeneous, and even the smallest particles can have shapes that deviate from a perfect sphere. 相似文献
994.
Nonlinear Dynamics - A nonlinear mathematical model is developed in the time domain to simulate the behaviour of two identical flexibly mounted cylinders in tandem while undergoing vortex-induced... 相似文献
995.
Potential Analysis - We extend the well-known result that any $f \in W^{1,n}({\Omega }, \mathbb {R}^{n})$ , ${\Omega } \subset \mathbb {R}^{n}$ with strictly positive Jacobian is actually... 相似文献
996.
Azarkh M Okle O Eyring P Dietrich DR Drescher M 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2011,212(2):450-454
Spin-label electron paramagnetic resonance (SL-EPR) spectroscopy has become a powerful and useful tool for studying structure and dynamics of biomacromolecules. However, utilizing these methods at physiological temperatures for in-cell studies is hampered by reduction of the nitroxide spin labels and thus short half-lives in the cellular environment. Consequently, reduction kinetics of two structurally different nitroxides was investigated in cell extracts of Xenopus laevis oocytes using rapid-scan cw-experiments at X-band. The five member heterocyclic ring nitroxide PCA (3-carboxy-2,2,5,5-tetramethylpyrrolidinyl-1-oxy) under investigation features much higher stability against intracellular reduction than the six member ring analog TOAC (2,2,6,6-tetramethylpiperidine-N-oxyl-4-amino-4-carboxilic acid) and is therefore a suitable spin label type for in-cell EPR. The kinetic data can be described according to the Michaelis–Menten model and thus suggest an enzymatic or enzyme-mediated reduction process. 相似文献
997.
998.
999.
1000.
Ernst Dietrich 《Fresenius' Journal of Analytical Chemistry》1866,5(1):293-299
Ohne Zusammenfassung 相似文献