全文获取类型
收费全文 | 16059篇 |
免费 | 2703篇 |
国内免费 | 1155篇 |
专业分类
化学 | 10143篇 |
晶体学 | 210篇 |
力学 | 1197篇 |
综合类 | 161篇 |
数学 | 2139篇 |
物理学 | 6067篇 |
出版年
2023年 | 107篇 |
2022年 | 382篇 |
2021年 | 365篇 |
2020年 | 506篇 |
2019年 | 538篇 |
2018年 | 499篇 |
2017年 | 574篇 |
2016年 | 646篇 |
2015年 | 581篇 |
2014年 | 735篇 |
2013年 | 1302篇 |
2012年 | 888篇 |
2011年 | 980篇 |
2010年 | 851篇 |
2009年 | 975篇 |
2008年 | 857篇 |
2007年 | 793篇 |
2006年 | 794篇 |
2005年 | 647篇 |
2004年 | 546篇 |
2003年 | 483篇 |
2002年 | 502篇 |
2001年 | 430篇 |
2000年 | 418篇 |
1999年 | 355篇 |
1998年 | 310篇 |
1997年 | 278篇 |
1996年 | 255篇 |
1995年 | 199篇 |
1994年 | 201篇 |
1993年 | 130篇 |
1992年 | 130篇 |
1991年 | 93篇 |
1990年 | 67篇 |
1989年 | 70篇 |
1988年 | 74篇 |
1987年 | 49篇 |
1985年 | 428篇 |
1984年 | 301篇 |
1983年 | 239篇 |
1982年 | 224篇 |
1981年 | 168篇 |
1980年 | 122篇 |
1979年 | 140篇 |
1978年 | 79篇 |
1977年 | 91篇 |
1976年 | 89篇 |
1975年 | 91篇 |
1974年 | 118篇 |
1973年 | 131篇 |
排序方式: 共有10000条查询结果,搜索用时 109 毫秒
81.
由于混凝土材料理化特性的差异,高强混凝土的弯压极限应变明显地小于普通混凝土,依据试验结果分析了高强混凝土的弯压极限应变变化规律,并给出了它的计算公式. 相似文献
82.
83.
《Chemistry (Weinheim an der Bergstrasse, Germany)》2006,12(13):3419-3419
84.
王同科 《高等学校计算数学学报(英文版)》2002,11(2):213-225
1 IntroductionFinitevolumeelementmethodorFVEMusesavolumeintegralformulationofthedif ferentialequationwithafinitepartitioningsetofvolumetodiscretizetheequation ,thenre strictstheadmissiblefunctionstoalinearfiniteelementspacetodiscretizethesolution ([1 -4 ] ) .… 相似文献
85.
王守宇 马英君 T.Komatsubara 刘运祚 张玉虎 梁国栋 K.Furuno T.Hayakawa J.Mukai Y.Iwata T.Morikawa G.B.Hagcmann G.Sletten J.Nyberg D.Je 《中国物理 C》2004,28(5):491-494
利用融合蒸发反应116Cd(14N,4n)126Cs布居了126Cs的高自旋态.观测到了100多条新的γ跃迁和相应的能级,建立了双奇核126Cs由9个转动带构成的能级纲图.尝试性地指定了大部分能级的自旋和宇称以及各转动带的Nilsson单粒子组态.极大地丰富了已有的实验结果. 相似文献
86.
G. A. Kohring 《Journal of statistical physics》1992,66(3-4):1177-1184
A hydrodynamic cellular automata (HDCA) for simulating two-dimensional fluids with large viscosities is proposed. The model is characterized by a mean free path which is of the same size as in the FHP-II model, but with a viscosity more than 10 times larger. This new model should make simulations of flows at low Reynolds number more efficient. 相似文献
87.
88.
89.
Mieko Tanaka-Yamawaki 《Annals of the Institute of Statistical Mathematics》2003,55(2):437-446
Contrary to the common sense in economics and financial engineering, price fluctuations at very fine level of motion exhibit
various evidences against the efficient market hypothesis. We attempt to investigate this issue by studying extensive amount
of foreign currency exchange data for over five years at the finest level of resolution. We specifically focus on the proposed
stability in binomial conditional probabilities originally found in much smaller examples of financial time series. In order
to handle very large data, we have written an efficient program in C that automatically generates those conditional probabilities.
It is found that the stability is maintained for extremely large time duration that covers almost the entire period. Based
on the length of conditions for which the conditional probabilities are distinguishable each other, we identify the length
of memory being less than 3 movements. 相似文献
90.
Yoshitomo Ono Naoyuki Kawashima Hiroto Kudo Tadatomi Nishikubo Takabumi Nagai 《Journal of polymer science. Part A, Polymer chemistry》2007,45(14):2978-2988
The ring‐opening copolymerization of a glycidyl ester derivative having a benzophenone group and the donor–acceptor norbornadiene (D‐A NBD) dicarboxylic acid, 5‐(4‐methoxyphenyl)‐1,4,6,7,7‐pentamethyl‐2,5‐norbornadiene‐2,3‐dicarboxylic acid, monoglycidyl ester derivatives with D‐A NBD dicarboxylic anhydride using tetraphenylphosphonium bromide as a catalyst proceeded smoothly to give novel self‐photosensitizing NBD polymers in good yields. The molecular weight of these polyesters was about 4,000, and lower than that of analogous NBD polymers having no benzophenone group. All the synthesized NBD polymers isomerized smoothly to the corresponding quadricyclane (QC) polymers upon UV irradiation in tetrahydrofuran (THF) solution and in the film state. The rate of the photoisomerization of the D‐A NBD moieties in these polymers was higher than that of the D‐A NBD moieties in the polymer having no photosensitizing group. Furthermore, the rate of the photoisomerization of the D‐A NBD moieties in these polymers was also higher than that of the NBD polymer with low molecular weight photosensitizer in dilute solution. The photo‐irradiated polymers having QC moieties released thermal energies of 146–180 J/g. The D‐A NBD moieties contained in these NBD polymers possessed fair to good fatigue resistance. The degradation of the NBD moieties in these polymers was 15–30% after 50 repeated cycles of interconversion. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2978–2988, 2007 相似文献