全文获取类型
收费全文 | 307877篇 |
免费 | 2315篇 |
国内免费 | 1172篇 |
专业分类
化学 | 139659篇 |
晶体学 | 4740篇 |
力学 | 17313篇 |
综合类 | 1篇 |
数学 | 56620篇 |
物理学 | 93031篇 |
出版年
2020年 | 1787篇 |
2019年 | 2044篇 |
2018年 | 12838篇 |
2017年 | 12597篇 |
2016年 | 9803篇 |
2015年 | 3194篇 |
2014年 | 4238篇 |
2013年 | 10341篇 |
2012年 | 11126篇 |
2011年 | 19456篇 |
2010年 | 12116篇 |
2009年 | 12475篇 |
2008年 | 15008篇 |
2007年 | 17137篇 |
2006年 | 8441篇 |
2005年 | 8704篇 |
2004年 | 8355篇 |
2003年 | 8002篇 |
2002年 | 7012篇 |
2001年 | 7304篇 |
2000年 | 5631篇 |
1999年 | 4366篇 |
1998年 | 3733篇 |
1997年 | 3599篇 |
1996年 | 3480篇 |
1995年 | 3122篇 |
1994年 | 3023篇 |
1993年 | 3129篇 |
1992年 | 3203篇 |
1991年 | 3393篇 |
1990年 | 3131篇 |
1989年 | 3083篇 |
1988年 | 3124篇 |
1987年 | 3011篇 |
1986年 | 2857篇 |
1985年 | 3855篇 |
1984年 | 4047篇 |
1983年 | 3233篇 |
1982年 | 3451篇 |
1981年 | 3373篇 |
1980年 | 3276篇 |
1979年 | 3377篇 |
1978年 | 3457篇 |
1977年 | 3368篇 |
1976年 | 3462篇 |
1975年 | 3156篇 |
1974年 | 3162篇 |
1973年 | 3218篇 |
1972年 | 2252篇 |
1971年 | 1857篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
Christiane Albrecht 《Analytical and bioanalytical chemistry》2008,390(5):1223-1224
102.
103.
104.
V. P. Ershov D. A. Kas’yanov V. I. Rodchenkov D. A. Sergeev 《Crystallography Reports》2008,53(2):339-343
The growth of the isolated (100) face of a KDP crystal at exposure of the phase boundary to the initial ultrasound field and a standing acoustic wave has been investigated. A significant growth response of this face, exposed to sound normally along the acoustic axis in the near zone of a piston-like half-wave vibrator with f = 20 kHz and tangentially in the pulsed two-frequency (f = 600 and 900 kHz) standing-wave mode, has been revealed. It is shown that the mechanisms of mass exchange enhancement in these acoustic modes are different. The results obtained show a fundamental possibility of controlling crystal growth and dissolution by varying the parameters of inhomogeneous acoustic field. 相似文献
105.
A. P. Voronov G. N. Babenko V. M. Puzikov A. D. Roshal’ V. I. Salo 《Crystallography Reports》2008,53(4):708-712
The features of doping of KDP crystals with cerium ions and organocerium complexes with alizarin complexon and arsenazo III have been investigated. It is established that “direct” doping by introducing cerium salts into the initial solution cannot be implemented. The effect of organometallic complexes of cerium on the crystal growth has been studied. Organocerium complexes predominantly enter the prismatic or pyramidal growth sectors. It is shown that the complex arsenazo III + Ce blocks the growth of the prismatic sector. Cerium-doped KDP crystals exhibit a photoluminescence band peaking at the wavelength λmax= 350 nm. 相似文献
106.
K. Morigaki K. Takeda H. Hikita C. Ogihara P. Roca i Cabarrocas 《Journal of Non》2008,354(19-25):2131-2134
Our model for light-induced defect creation in hydrogenated amorphous silicon is applied to its kinetics, i.e., the growing curve of light-induced dangling bond density as a function of illumination time, which is fitted to a stretched exponential function. Two parameters β and τ involved in the function are estimated as functions of saturated dangling bond density in terms of our model. These are compared with two experimental results, i.e., our results obtained from ESR measurements and Shimakawa et al.’s results obtained from photoconductivity measurements. The saturated dangling bond density is also measured as a function of the generation rate of free carriers. The experimental results are compared with calculated results and discussed. 相似文献
107.
Chengzhi Qi Mingyang Wang Qihu Qian Jianjie Chen 《Moscow University Mechanics Bulletin》2008,63(5):113-121
The formation mechanisms for the structural hierarchy in geological media are discussed. It is shown that the formation of such a hierarchy is caused by certain external and internal circumstances. The first ones consist in the fact that, because of external actions, the Earth’s poles continuously execute the translational and rotational motions responsible for a regular structure of rock fracture and for the appearance of the scale factor √2. The second ones consist in the fact that, under the action of many random factors and because of external actions, during the formation of geological media there appear dissipative structures and, hence, some self-similar fractal structures are formed. 相似文献
108.
109.
110.
M C Testik J K Cochran G C Runger 《The Journal of the Operational Research Society》2004,55(3):233-239
We study the short-term staffing problem of systems that experience random, non-stationary demand. The typical method to accommodate changes in arrival rate is to use historical data to identify peak periods and associated forecasting for upcoming time windows. In this paper, we develop a method that instead detects change as it happens. Motivated by an automatic call distributor system in a call centre with time-varying arrivals, we propose a change detection algorithm based upon non-homogeneous Poisson processes. The proposed method is general and may be thought of as a feed-forward strategy, in which we detect a change in the arrival process, estimate the new magnitude of the arrival rate, and assign an appropriate number of servers to the tasks. The generalized likelihood ratio statistic is used and a recommendation for its decision limit is developed. Simulation results are used to evaluate the performance of the detector in the context of a telephone call centre. 相似文献