全文获取类型
收费全文 | 712293篇 |
免费 | 7181篇 |
国内免费 | 2534篇 |
专业分类
化学 | 356386篇 |
晶体学 | 10026篇 |
力学 | 36368篇 |
综合类 | 78篇 |
数学 | 102763篇 |
物理学 | 216387篇 |
出版年
2021年 | 5879篇 |
2020年 | 6473篇 |
2019年 | 7200篇 |
2018年 | 13686篇 |
2017年 | 14041篇 |
2016年 | 15615篇 |
2015年 | 8053篇 |
2014年 | 12540篇 |
2013年 | 29227篇 |
2012年 | 25272篇 |
2011年 | 34021篇 |
2010年 | 24026篇 |
2009年 | 23887篇 |
2008年 | 31371篇 |
2007年 | 33194篇 |
2006年 | 23963篇 |
2005年 | 24312篇 |
2004年 | 21142篇 |
2003年 | 19405篇 |
2002年 | 18314篇 |
2001年 | 18679篇 |
2000年 | 14604篇 |
1999年 | 11072篇 |
1998年 | 9515篇 |
1997年 | 9338篇 |
1996年 | 8979篇 |
1995年 | 8022篇 |
1994年 | 8072篇 |
1993年 | 7737篇 |
1992年 | 8275篇 |
1991年 | 8684篇 |
1990年 | 8244篇 |
1989年 | 8131篇 |
1988年 | 7919篇 |
1987年 | 7626篇 |
1986年 | 7393篇 |
1985年 | 9578篇 |
1984年 | 9944篇 |
1983年 | 8362篇 |
1982年 | 8779篇 |
1981年 | 8205篇 |
1980年 | 7784篇 |
1979年 | 8334篇 |
1978年 | 8707篇 |
1977年 | 8541篇 |
1976年 | 8563篇 |
1975年 | 8111篇 |
1974年 | 8025篇 |
1973年 | 8386篇 |
1972年 | 6190篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
971.
Nešetřil and Sopena introduced the concept of oriented game chromatic number. They asked whether the oriented game chromatic
number of partial k-trees was bounded. Here we answer their question positively.
Received: January 12, 2001 Final version received: February 25, 2002 相似文献
972.
973.
It is a well-known feature of odd space-time dimensions d that there exist two inequivalent fundamental representations A and B of the Dirac gamma matrices. Moreover, the parity transformation swaps the fermion fields living in A and B. As a consequence, a parity-invariant Lagrangian can only be constructed by incorporating both the representations. Based upon these ideas and contrary to long-held belief, we show that in addition to a discrete exchange symmetry for the massless case, we can also define chiral symmetry provided the Lagrangian contains fields corresponding to both the inequivalent representations. We also study the transformation properties of the corresponding chiral currents under parity and charge-conjugation operations. We work explicitly in 2 + 1 dimensions and later show how some of these ideas generalize to an arbitrary number of odd dimensions. 相似文献
974.
V. A. Popov S. I. Lopatin L. Sh. Tsemekhman L. A. Pavlinova S. P. Kormilitsyn V. V. Barsegyan 《Russian Journal of Applied Chemistry》2003,76(10):1564-1567
Evaporation of chromium ore and concentrates was studied using high-temperature differential mass-spectrometry. The data obtained, concerning the component vapor pressures in evaporation of complex oxide systems in the range 1700-2100 K, can be used to calculate the evaporation loss in melting and to assess the possibility of utilization of the sublimates formed. 相似文献
975.
The ρ-T curves in our single phase HgBa2Ca2Cu3O8+δ superconductor were measured as a function of temperature and magnetic field, ρ=ρ0exp(−Ueff/κBT). It can be transformed to another form d(lnρ)/d(1/T)=−Ueff+TdUeff/dT, then this becomes a plot of the activation energy Ueff as a function of temperature. Our data plotted in these ways show a clear crossover from high-temperature two-dimensional vortex-liquid to a critical region associated with the low-temperature three-dimensional vortex-glass phase transition. The critical exponents v(z−1)=3.9±1.9 in this system are little different with previous measurements in BSCCO and YBCO systems. 相似文献
976.
R. Norvaisa 《Lithuanian Mathematical Journal》2005,45(4):447-457
We give a characterization of Gaussian chaos laws on Banach function spaces which do not contain ℓ
∞
n
's uniformly. The result is applied to describe the convergence in law of U-processes with sample paths in certain Banach function spaces.
__________
Published in Lietuvos Matematikos Rinkinys, Vol. 45, No. 4, pp. 553–566, October–December, 2005. 相似文献
977.
A. V. Tkachev 《Chemistry of Natural Compounds》1987,23(4):393-412
A review is given of the literature over the period from the middle of the 1950s to the beginning of the 1980s on the distribution in nature, the biological activity, the conformation, and the chemical transformations of sesquiterpenes of the caryophyllene type. 相似文献
978.
Harish C. Bahl Stanley Zionts 《The Journal of the Operational Research Society》1987,38(12):1141-1148
Scheduling the production of several items requires the determination of production quantities in different periods in the presence of resource constraints. Several approximate and heuristic algorithms have been proposed to solve this problem. However, no method for finding an optimal solution has as yet been developed. It is shown that the problem may be solved advantageously using Benders' decomposition. The subproblem in Benders' decomposition is shown to be a transportation problem, and some strategies for solving the master problem are indicated. The paper concludes with a sample problem demonstrating the application of the method. 相似文献
979.
980.