全文获取类型
收费全文 | 4784篇 |
免费 | 650篇 |
国内免费 | 580篇 |
专业分类
化学 | 1123篇 |
晶体学 | 47篇 |
力学 | 670篇 |
综合类 | 126篇 |
数学 | 2164篇 |
物理学 | 1884篇 |
出版年
2024年 | 12篇 |
2023年 | 52篇 |
2022年 | 83篇 |
2021年 | 110篇 |
2020年 | 85篇 |
2019年 | 111篇 |
2018年 | 109篇 |
2017年 | 153篇 |
2016年 | 167篇 |
2015年 | 149篇 |
2014年 | 250篇 |
2013年 | 344篇 |
2012年 | 279篇 |
2011年 | 302篇 |
2010年 | 232篇 |
2009年 | 336篇 |
2008年 | 351篇 |
2007年 | 367篇 |
2006年 | 297篇 |
2005年 | 270篇 |
2004年 | 232篇 |
2003年 | 235篇 |
2002年 | 212篇 |
2001年 | 175篇 |
2000年 | 152篇 |
1999年 | 155篇 |
1998年 | 127篇 |
1997年 | 120篇 |
1996年 | 90篇 |
1995年 | 71篇 |
1994年 | 74篇 |
1993年 | 31篇 |
1992年 | 49篇 |
1991年 | 32篇 |
1990年 | 23篇 |
1989年 | 15篇 |
1988年 | 24篇 |
1987年 | 11篇 |
1986年 | 15篇 |
1985年 | 17篇 |
1984年 | 19篇 |
1983年 | 12篇 |
1982年 | 8篇 |
1981年 | 8篇 |
1980年 | 8篇 |
1979年 | 7篇 |
1978年 | 6篇 |
1976年 | 4篇 |
1974年 | 6篇 |
1973年 | 5篇 |
排序方式: 共有6014条查询结果,搜索用时 203 毫秒
81.
An approach to analysis of pigment release from microcapsules with size distribution 总被引:2,自引:0,他引:2
Takao Yamamoto Toshiaki Dobashi Miho Kimura Chih Pong Chang 《Colloids and surfaces. B, Biointerfaces》2002,25(4):305-311
We have studied the release curve for microcapsules with size distribution. On the basis of an analogy to the relaxation phenomena with multiple characteristic times, we propose a stretched exponential release curve for the system with size distribution and relate the release curve to the size distribution function of the microcapsule. This method was successfully applied to the transfer of azo-pigments from inner medium of dioctyl phthalate to dispersing medium of methanol through poly(ureaurethane) microcapsule membrane. 相似文献
82.
A multireference configurational interaction method based on the separated electron pair (SEP) wave functions, SEP‐CI approach, has been developed as an approximation to the traditional CASSCF method. It differs from the CASSCF method in that active orbitals are obtained from the SEP wave function without further optimization in the subsequent CI calculations, and the active space is automatically constructed according to the occupation coefficients of SEP natural orbitals. These features make the present SEP‐CI method computationally much less demanding than the CASSCF method. The applicability of the SEP‐CI method is illustrated with sample calculations on the insertion reaction of BeH2 and dissociation energies of LiH, BH, FH, H2O, and N2. © 2005 Wiley Periodicals, Inc. J Comput Chem 27: 39–47, 2006 相似文献
83.
An equation for a polarization curve of a hydrophobized electrode is proposed for electrosynthesis of a soluble electroactive product in an inner-kinetic mode. The equation contains the concentration of the target product (TP) in an explicit form. The shape of the curve depends on the biquadratic root of the TP concentration and the square root of the ratio between exchange currents of the side and target reactions. 相似文献
84.
85.
碳纳米管电极超大容量离子电容器交流阻抗特性 总被引:18,自引:0,他引:18
采用碳纳米管作为超大容量离子电容器的电极材料,应用交流阻抗频谱法,研究了超大容量离子电容器的频率响应特性.结果表明,用碳纳米管块作电极,超大容量离子电容器在频率250 mHz以下出现“电荷饱和”;而用活性炭块作电极, 超大容量离子电容器在频率为100 mHz时仍未出现“电荷饱和”,这说明碳纳米管电极超大容量离子电容器的频率响应特性优于活性炭电极超大容量离子电容器的频率响应特性.上述两类超大容量离子电容器的阻抗谱中均出现倾角约为45°的直线段,其相位角均远小于理想电容器的相位角90°. 相似文献
86.
87.
Fashui?HongEmail author Xuefeng?Wang Chao?Liu Guoxing?Su Weiping?Song Kang?Wu Ye?Tao Guiwen?Zhao 《中国科学B辑(英文版)》2003,46(1):42-50
It was studied by spectroscopy that PSII reaction center complex consisting of three polypeptides, D1, D2 and Cytb559, were purified from PSII particle of CeCl3 treated spinach. The results of the experiment show that Ce3+ could improve the growth of spinach, and accelerate electron transport of PSII particles. Of chl-a of UV-Vis spectrum of
D1/D2/Cytb559 complex, Soret band was blue-shifted by 3 nm and Q band by 2 nm, respectively, and the fluorescence emission
peak was blue-shifted by 5 nm in CeCl3-treated spinach compared with the one in control. By the extended X-ray absorption fine structure (EXAFS) spectroscopy methods,
it has been found that Ce3+ is coordinated with 8 nitrogen atoms in the first coordination shell with Ce-N bond length of 0.253 nm, and Ce3+ with 6 oxygen atoms in the second coordination shell with Ce-O bond length of 0.32 nm. However, the secondary structure of
D1/D2/Cytb559 complex by circular dichroism (CD) spectroscopy has no significant change after CeCl3 treated. It might be that Ce3+ binds to porphyrin rings of chlorophyll and oxygen of amino acid residue of polypeptide in D1/D2/Cytb559 complex, and then
accelerates the primary reaction of PSII, intensifies function of P680+ primary electron donor of D1/D2/Cytb559, but there is little change in conformation of PSII reaction center complex. 相似文献
88.
《Expositiones Mathematicae》2022,40(4):1096-1115
We study two classical families of enumerative problems: inflection lines of plane curves and theta-hyperplanes of canonical curves. In these problems the complex counts and the tropical counts disagree. Each problem suggests a prime with special behavior. On the one hand, we analyze the reduction modulo these special primes, and we prove that the complex solutions coalesce in uniform clusters. On the other hand, we observe that the counts in special characteristic and in tropical geometry match. 相似文献
89.
令X=(n1,n2,…,nt),Y=(m1,m2,…,mt)是两个t维递减序列.如果对所有的j,1≤j≤t,都有∑i=1~j、ni≥∑i=1~j mi以及∑i=1~t ni=∑i=1~t mi,则称X可盖Y,记作X■Y.如果X≠Y,则记作X■Y.本文考虑联图G(n1,n2,…,nt;a)=(Kn1∪n2∪…∪Knt)∨Ka的谱半径,这里n1+n2+…+nt+a=n,(n1,n 相似文献
90.
In this paper we investigate two-point algebraic-geometry codes (AG codes) coming from the Beelen-Montanucci (BM) maximal curve. We study properties of certain two-point Weierstrass semigroups of the curve and use them for determining a lower bound on the minimum distance of such codes. AG codes with better parameters with respect to comparable two-point codes from the Garcia-Güneri-Stichtenoth (GGS) curve are discovered. 相似文献