全文获取类型
收费全文 | 76356篇 |
免费 | 13243篇 |
国内免费 | 7817篇 |
专业分类
化学 | 53218篇 |
晶体学 | 700篇 |
力学 | 4881篇 |
综合类 | 383篇 |
数学 | 8516篇 |
物理学 | 29718篇 |
出版年
2024年 | 290篇 |
2023年 | 1651篇 |
2022年 | 2815篇 |
2021年 | 2891篇 |
2020年 | 3211篇 |
2019年 | 3040篇 |
2018年 | 2654篇 |
2017年 | 2453篇 |
2016年 | 3725篇 |
2015年 | 3607篇 |
2014年 | 4308篇 |
2013年 | 5492篇 |
2012年 | 6969篇 |
2011年 | 6978篇 |
2010年 | 4653篇 |
2009年 | 4443篇 |
2008年 | 4808篇 |
2007年 | 4307篇 |
2006年 | 3913篇 |
2005年 | 3285篇 |
2004年 | 2570篇 |
2003年 | 2025篇 |
2002年 | 1880篇 |
2001年 | 1585篇 |
2000年 | 1437篇 |
1999年 | 1592篇 |
1998年 | 1342篇 |
1997年 | 1319篇 |
1996年 | 1325篇 |
1995年 | 1088篇 |
1994年 | 948篇 |
1993年 | 779篇 |
1992年 | 686篇 |
1991年 | 599篇 |
1990年 | 514篇 |
1989年 | 401篇 |
1988年 | 343篇 |
1987年 | 283篇 |
1986年 | 256篇 |
1985年 | 211篇 |
1984年 | 143篇 |
1983年 | 108篇 |
1982年 | 80篇 |
1981年 | 68篇 |
1980年 | 66篇 |
1979年 | 35篇 |
1978年 | 30篇 |
1977年 | 41篇 |
1976年 | 30篇 |
1973年 | 28篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
A two-step swelling procedure was adopted to synthesize mono-dispersed and highly cross-linked poly (St-divinylbenzene) particles
with PSt micro-spheres (1.80 μm in diameter). The PSt micro-spheres were prepared by a dispersion polymerization method and
used as seeds. The effects of monomer concentration, ratio of ethanol to water, swelling reagents, crosslinking reagents,
swelling temperature and agitation speed on particle size were investigated in detail. The morphologies and size distributions
of these micro-spheres were examined by SEM and particle size analysis (PSA). The T
g of the micro-spheres was measured by DSC. The results indicate that the particles (6.20 μm in diameter) exhibit excellent
mono dispersed property and high crosslinking degree when the concentration of the swelling reagent was 25%, the concentration
of the crosslinking reagents was 23%, the swelling temperature was 30°C and the stirring speed was 150 r/min.
__________
Translated from Chinese Journal of Applied Chemistry, 2007, 24(11): 1289–1294 相似文献
92.
J. Song H. Jiang Z.J. Liu D.Y. Khang Y. Huang J.A. Rogers C. Lu C.G. Koh 《International Journal of Solids and Structures》2008,45(10):3107-3121
A finite-deformation theory is developed to study the mechanics of thin buckled films on compliant substrates. Perturbation analysis is performed for this highly nonlinear system to obtain the analytical solution. The results agree well with experiments and finite element analysis in wavelength and amplitude. In particular, it is found that the wavelength depends on the strain. Based on the accurate wavelength and amplitude, the membrane and peak strains in thin films, and stretchability and compressibility of the system are also obtained analytically. 相似文献
93.
Pengbo Jiang Tiexin Cheng Yan Liu Xianghao Cui Yingli Bi Kaiji Zhen 《Reaction Kinetics and Catalysis Letters》2004,82(1):49-56
The novel phase transfer catalysts S-8 [4-(dimethyloctylammonium) propansultan] and DB-X [1,4-bis(triethylmethylammonium)benzene dibromide] were synthesized and employed for high conversion synthesis of dichlorocyclopropane from various olefins.This revised version was published online in December 2005 with corrections to the Cover Date. 相似文献
94.
稀疏过程在破产问题中的应用 总被引:5,自引:0,他引:5
本讨论一类人寿保险的风险过程,其中保单到达服从齐次Poisson过程。而描述退保及索赔发生的计数过程分别为这一过程的q-稀疏与p-稀疏.对此模型给出其破产概率的具体上界,并与其它一类风险模型进行比较. 相似文献
95.
The title compound, [Cd(SeCN)2(pyCN)2]∞, adopts an extended one‐dimensional chain structure in which the neighboring cadmium atoms are bridged by two selenocyanate ions. The central cadmium atom has a distorted octahedral geometry defined by two isonicotinonitrile and four selenocyanate ions in a 4N2Se fashion. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
96.
97.
In mononuclear HgI2[(C5H4N)3N], mercury is tetrahedrally coordinated by two nitrogen atoms of a tris(2‐pyridyl)amine ligand and two iodides. The coordination moieties are connected by weak intermolecular Hg(II)···I interactions to give a one‐dimensional structure. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
98.
99.
The original article to which this Erratum refers was published in Journal of Graph Theory 47:129–146,2004 . 相似文献
100.
LiuYuqi LiZhigang YahYakun 《Acta Mechanica Solida Sinica》2004,17(1):58-64
By using the Finite Element Inverse Approach based on the Hill quadratic anisotrop-ically yield criterion and the quadrilateral element, a fast analyzing software-FASTAMP for the sheet metal forming is developed. The blank shapes of three typical stampings are simulated and compared with numerical results given by the AUTOFORM software and experimental results, respectively. The comparison shows that the FASTAMP can predict blank shape and strain distribution of the stamping more precisely and quickly than those given by the traditional methods and the AUTOFORM. 相似文献