全文获取类型
收费全文 | 2505篇 |
免费 | 155篇 |
国内免费 | 8篇 |
专业分类
化学 | 1634篇 |
晶体学 | 20篇 |
力学 | 25篇 |
数学 | 541篇 |
物理学 | 448篇 |
出版年
2024年 | 8篇 |
2023年 | 25篇 |
2022年 | 37篇 |
2021年 | 58篇 |
2020年 | 54篇 |
2019年 | 72篇 |
2018年 | 64篇 |
2017年 | 46篇 |
2016年 | 122篇 |
2015年 | 122篇 |
2014年 | 120篇 |
2013年 | 290篇 |
2012年 | 190篇 |
2011年 | 183篇 |
2010年 | 104篇 |
2009年 | 83篇 |
2008年 | 96篇 |
2007年 | 70篇 |
2006年 | 90篇 |
2005年 | 69篇 |
2004年 | 47篇 |
2003年 | 46篇 |
2002年 | 53篇 |
2001年 | 29篇 |
2000年 | 38篇 |
1999年 | 25篇 |
1998年 | 25篇 |
1997年 | 16篇 |
1996年 | 25篇 |
1995年 | 16篇 |
1994年 | 22篇 |
1993年 | 12篇 |
1992年 | 29篇 |
1991年 | 25篇 |
1990年 | 22篇 |
1989年 | 18篇 |
1988年 | 12篇 |
1987年 | 16篇 |
1986年 | 12篇 |
1985年 | 26篇 |
1984年 | 24篇 |
1983年 | 15篇 |
1982年 | 18篇 |
1981年 | 18篇 |
1980年 | 19篇 |
1979年 | 10篇 |
1978年 | 14篇 |
1977年 | 17篇 |
1976年 | 18篇 |
1973年 | 10篇 |
排序方式: 共有2668条查询结果,搜索用时 15 毫秒
11.
A. Ádám 《Acta Mathematica Hungarica》1989,54(3-4):291-296
12.
Oscillatory change of pH occurs during the chromate-catalyzed decomposition of hydrogen peroxide in a weakly acidic medium at elevated temperature and at high initial concentration of hydrogen peroxide. In a closed system, there are only two or three periods, but sustained oscillation occurs in a CSTR. In a CSTR bistability is also found. In closed systems the temperature exhibits a great maximum (up to 15°C increase), in a CSTR sustained oscillation occurs at a constant stationary temperature. 相似文献
13.
14.
R. Schuch I. Bergström K. Blaum T. Fritioff Sz. Nagy A. Solders M. Suhonen 《Hyperfine Interactions》2006,173(1-3):73-83
We report here about measurements of reaction and decay Q values by precise determination of pairs of atomic masses. These were performed with the Penning trap mass spectrometer SMILETRAP.
Measurements with Penning traps give reliable and accurate masses, in particular Q values, due to the fact that certain systematic errors to a great deal cancel in the mass difference between the two atoms
defining the Q value. Some Q values that are of fundamental interest will be discussed here, for example, a new Q value for the 6Li (n,γ) 7Li reaction, for the β-decay of tritium, related to properties of the electron neutrino mass, and for the neutrino-less double
β-decay of 76Ge, related to the question of whether the neutrino is a Majorana particle or not. In case of the latter two we report the
most accurate Q values, namely 18,589.8(12) eV for the tritium decay and 2,038.997(46) keV for the neutrino-less double β-decay of 76Ge. 相似文献
15.
A textured pellet of YBa2Cu3O7?δ was prepared and doped with57Co. After subsequent heat treatments the cobalt was found at the two copper sites. The degree of alignment of individual crystallites (about 40%) was determined from the Mössbauer spectrum by using a method developed by the authors [1]. The same method showed that the most characteristic doublet component of such spectra (δ=0.08 mm/s; |ΔE Q|=1.96 mm/s) is associated with a site, most probably a Cu(1) site, where the EFG is parallel to thec direction of the unit cell. The sign ofV zz turned out to be negative, giving a negative quadrupole splitting (ΔE Q=?1.96 mm/s) for that component. 相似文献
16.
17.
The present state of a long term program is reviewed. It was started to elaborate a remote controlled automated radiochemical
processing system for the neutron activation analysis of biological materials. The system is based on wet ashing of the sample,
followed by reactive desorption of some volatile components. The distillation residue is passed through a series of columns
filled with selective ion screening materials to remove the matrix activity. The solution is thus “stripped” from the interfering
radioions, and it is processed to single-elements through group separations using ion-exchange chromatographic techniques.
Some special problems concerning this system are treated. (a) General aspects of the construction of a (semi)automated radiochemical
processing system are discussed; (b) Comparison is made between various technical realizations of the same basic concept;
(c) Some problems concerning the “reconstruction” of an already published processing system are outlined. 相似文献
18.
Tuoto C. V. Regina A. Nagy J. B. Nastro A. 《Journal of Thermal Analysis and Calorimetry》1998,54(3):891-899
DSC, TG and quadrupole mass spectrometer data concerning methylquinuclidinium iodide (MeQ1), dried precursor gel, and crystalline
levyne-type zeolite are discussed together with the thermal degradation of MeQ1 mixed with single inorganic components of
the gel.
It is shown that MeQ+ions play a role in the organization of the gel structure.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
19.
For ν≥0 let cνk be the k-th positive zero of the cylinder functionC v(t)=J v(t)cosα-Y v(t)sinα, 0≤α>π whereJ ν(t) andY ν(t) denote the Bessel functions of the first and the second kind, respectively. We prove thatC v,k 1+H(x) is convex as a function of ν, ifc νk≥x>0 and ν≥0, whereH(x) is specified in Theorem 1.1. 相似文献
20.