全文获取类型
收费全文 | 118812篇 |
免费 | 8172篇 |
国内免费 | 6225篇 |
专业分类
化学 | 58954篇 |
晶体学 | 1373篇 |
力学 | 5718篇 |
综合类 | 391篇 |
数学 | 12246篇 |
物理学 | 35520篇 |
无线电 | 19007篇 |
出版年
2023年 | 1322篇 |
2022年 | 1924篇 |
2021年 | 2768篇 |
2020年 | 2954篇 |
2019年 | 3117篇 |
2018年 | 3485篇 |
2017年 | 3407篇 |
2016年 | 4244篇 |
2015年 | 3179篇 |
2014年 | 4512篇 |
2013年 | 6088篇 |
2012年 | 6490篇 |
2011年 | 6823篇 |
2010年 | 5380篇 |
2009年 | 5550篇 |
2008年 | 5809篇 |
2007年 | 5381篇 |
2006年 | 4967篇 |
2005年 | 4441篇 |
2004年 | 3794篇 |
2003年 | 3476篇 |
2002年 | 3526篇 |
2001年 | 3139篇 |
2000年 | 2530篇 |
1999年 | 2118篇 |
1998年 | 1956篇 |
1997年 | 1725篇 |
1996年 | 1600篇 |
1995年 | 1325篇 |
1994年 | 1343篇 |
1993年 | 1278篇 |
1992年 | 1213篇 |
1991年 | 1272篇 |
1990年 | 1224篇 |
1989年 | 1110篇 |
1988年 | 947篇 |
1987年 | 952篇 |
1986年 | 910篇 |
1985年 | 943篇 |
1984年 | 934篇 |
1983年 | 844篇 |
1982年 | 817篇 |
1979年 | 808篇 |
1978年 | 815篇 |
1977年 | 814篇 |
1976年 | 922篇 |
1975年 | 814篇 |
1974年 | 846篇 |
1973年 | 848篇 |
1972年 | 755篇 |
排序方式: 共有10000条查询结果,搜索用时 109 毫秒
981.
We obtain global heat kernel bounds for semigroups which need not be ultracontractive by transferring them to appropriately chosen weighted spaces where they become ultracontractive. Our construction depends upon two assumptions: the classical Sobolev imbedding and a “desingularizing” (L1,L1) bound on the weighted semigroup. 相似文献
982.
Mechanisms of the self-organization of nanosystems at the condensation of the extremely weak steady flows of copper vapors
obtained in magnetron sputtering in an ultrapure argon are studied. It is shown that the free-energy minimization near equilibrium
condensation creates prerequisites for the self-organization of statistically homogeneous layers of nanoclusters and determines
the transition to the formation of nanosystems in the form of fractal networks.
Original Russian Text ? V.I. Perekrestov, A.S. Kornyushchenko, Yu.A. Kosminskaya, 2007, published in Pis’ma v Zhurnal éksperimental’noĭ
i Teoreticheskoĭ Fiziki, 2007, Vol. 86, No. 12, pp. 879–883. 相似文献
983.
984.
985.
986.
Yu. G. Slizhov M. A. Gavrilenko 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2006,80(3):489-490
The separation of mixtures of phenols, alcohols, and alkylbenzenes by gas chromatography on adsorption layers of nickel and copper alizarinates was investigated. The thermodynamic parameters were calculated. It was shown that the sorbates differ in strength of interaction with the copper and nickel ions in their alizarin complexes. 相似文献
987.
Yu. V. Pokonova 《Russian Journal of Applied Chemistry》2007,80(11):1964-1968
Advantage of use residue from thermal cracking and products of its condensation as components of the mixture for manufacturing mechanically rigid (93%) granulated and ground carbon sorbents with extended volume of micropores (up to 0.27 cm3/cm3), showing enhanced sorption activity (E is up to 25.6 kJ mol?1) and high ability of separation various gas mixtures is demonstrated. As a carrier for medicine preparations these adsorbents show higher performance as compared with industrial samples. Solutions of the cracking residue can be used for impregnation of worked out zeolites for petroleum technology and for production of organomineral adsorbents with high adsorption capacity on extraction mercury from sewages. 相似文献
988.
Yu. G. Tselishchev 《Colloid Journal》2007,69(4):537-539
The capillary pressure in a liquid interlayer between two spherical particles is calculated as a function of their sizes and the wetting properties of the liquid. 相似文献
989.
Reaction of diethoxyphosphorylimine of methyl trifluoropyruvate with 1,3-C,N-and-N,N-binucleophiles led to a variety of N-phosphorylated fluorine-containing heterocycles, including the fused ones.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2176–2178, November, 2007. 相似文献
990.
The crystallization behavior of miscible syndiotactic polystyrene (sPS) and atactic polystyrene (aPS) blends with different sPS/aPS weight ratios was investigated in supercritical CO2 by using Fourier‐transform infrared spectroscopy, differential scanning calorimetry, and wide‐angle X‐ray diffraction. Supercritical CO2 and aPS exhibited different effects on the conformational change of sPS and competed with each other. Increasing the content of amorphous aPS in the blends made its effect on the conformational change of sPS gradually surpass that of supercritical CO2. Supercritical CO2 favored the formation of the helical conformation of sPS in lower temperature range and the all trans planar conformation in higher temperature range, instead of forming the latter one only in higher temperature range in ambient atmosphere. However, increasing aPS content in the blends pushed the range for forming the helical conformation to lower temperature and made the all trans planar conformation dominant in aPS/sPS 25/75 blend after treating in supercritical CO2 above 60 °C. The all trans planar zigzag conformation was more favorable than the helical conformation after mixing aPS in sPS in supercritical CO2. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1755–1764, 2007 相似文献