全文获取类型
收费全文 | 530149篇 |
免费 | 4198篇 |
国内免费 | 1286篇 |
专业分类
化学 | 269969篇 |
晶体学 | 7750篇 |
力学 | 26033篇 |
综合类 | 17篇 |
数学 | 67873篇 |
物理学 | 163991篇 |
出版年
2021年 | 5414篇 |
2020年 | 5814篇 |
2019年 | 6235篇 |
2018年 | 8422篇 |
2017年 | 8565篇 |
2016年 | 11647篇 |
2015年 | 6200篇 |
2014年 | 10451篇 |
2013年 | 23519篇 |
2012年 | 18367篇 |
2011年 | 21827篇 |
2010年 | 16433篇 |
2009年 | 16287篇 |
2008年 | 20674篇 |
2007年 | 20531篇 |
2006年 | 18637篇 |
2005年 | 16636篇 |
2004年 | 15478篇 |
2003年 | 13971篇 |
2002年 | 13864篇 |
2001年 | 14734篇 |
2000年 | 11346篇 |
1999年 | 8755篇 |
1998年 | 7601篇 |
1997年 | 7473篇 |
1996年 | 6931篇 |
1995年 | 6258篇 |
1994年 | 6266篇 |
1993年 | 6020篇 |
1992年 | 6376篇 |
1991年 | 6867篇 |
1990年 | 6578篇 |
1989年 | 6488篇 |
1988年 | 6324篇 |
1987年 | 6133篇 |
1986年 | 5871篇 |
1985年 | 7413篇 |
1984年 | 7771篇 |
1983年 | 6535篇 |
1982年 | 6820篇 |
1981年 | 6327篇 |
1980年 | 6003篇 |
1979年 | 6505篇 |
1978年 | 6743篇 |
1977年 | 6629篇 |
1976年 | 6587篇 |
1975年 | 6302篇 |
1974年 | 6129篇 |
1973年 | 6424篇 |
1972年 | 4706篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
231.
232.
A. V. Potepun 《Journal of Mathematical Sciences》2007,141(5):1545-1556
In part I of the paper, we have defined n-dimensional C0-manifolds in ℝn(m ≥ n) with locally-finite n-dimensional variations (a generalization of locally-rectifiable curves to dimensionn > 1) and
integration of measurable differential n-forms over such manifolds. The main result of part II states that an n-dimensional
manifold that is C1-embedded into ℝm has locally-finite variations and the integral of a measurable differential n-form defined in part I can be calculated by
the well-known formula. Bibliography: 5 titles.
__________
Translated from Zapiski Nauchnykh Seminarov POMI, Vol. 333, 2006, pp. 66–85. 相似文献
233.
A technique for variation of the temperature factor of free-flight models by varying their initial temperature is described. An experiment on a ballistic range is carried out with a free-flying supersonic blunt cone with a half-angle of 15° at a Mach number of 2.3. The flow at the cone base is studied in the transition range (from the laminar to turbulent flow) of Reynolds numbers. The base flow pattern is determined from the shadowgraphs of the flow about the models. The drag coefficient of the blunt cone at a zero angle of attack is found by processing trajectory data. It is found that the near wake geometries and the drag coefficients of the models tested at the laboratory temperature and a temperature of 120 K differ. Explanations of this effect are given. 相似文献
234.
The adsorption of nonionic surfactant Triton X-100 on quartz sand and methylated quartz sand from water and toluene was investigated by means of spectrophotometry, the radiotracer technique, and wetting angle measurements. 相似文献
235.
236.
Audrey A S G Lonni Ieda S Scarminio Lucas M C Silva Dalva T Ferreira 《Analytical sciences》2003,19(7):1013-1017
Phytochemical investigation of the aerial parts of three Baccharis species (Asteraceae family) was performed using HPLC and chemometric methods, with the objective of distinguishing between three morphologically very similar species: Baccharis genistelloides Persoon var. trimera (Less.) DC, B. milleflora (Less.) DC and B. articulata (Lam.) Persoon. With the help of Principal Component Analysis (PCA) and variance weights, it was possible to characterize the chromatographic profiles of the alcoholic extracts of the three species. Application of Soft Independent Modeling of Class Analogy (SIMCA) and K-Nearest Neighbor (KNN) methods on a training set of 74 extracts resulted in models that correctly classified all eight samples in an independent test set. 相似文献
237.
A. Touraille 《Algebra Universalis》1995,33(2):196-206
Presented by S. Burris. 相似文献
238.
A. M. Gurin 《Journal of Mathematical Sciences》2007,146(1):5505-5508
The number of combinatorially nonequivalent Dirichlet-Voronoi diagrams constructed for the centers of balls in the packing
obtained from the densest lattice packing of equal spheres by a small displacement of the spheres is estimated.
__________
Translated from Fundamentalnaya i Prikladnaya Matematika, Vol. 11, No. 5, pp. 79–84, 2005. 相似文献
239.
A. G. Chentsov 《Russian Mathematics (Iz VUZ)》2007,51(11):55-68
We consider a problem which implies the choice of a solution subject to asymptotic constraints. We represent the results as ultrafilters of the space of ordinary estimates (the space is not necessarily endowed with a topology). This representation corresponds to an abstract attainability problem in its nonsequential asymptotic version. 相似文献
240.
A. V. Pukhlikov 《Journal of Mathematical Sciences》2007,140(2):303-320
Combining the connectedness principle of Shokurov and Kollár, we develop a new technique of studying birational maps of natural
Fano fiber spaces. We prove that the only structures of a rationally connected fibration on direct products of typical Fano
varieties are projections onto the factors. In particular, the groups of biregular and birational self-maps of Fano direct
products coincide.
__________
Translated from Fundamentalnaya i Prikladnaya Matematika, Vol. 10, No. 4, pp. 183–206, 2004. 相似文献