全文获取类型
收费全文 | 4914篇 |
免费 | 1256篇 |
国内免费 | 2435篇 |
专业分类
化学 | 4224篇 |
晶体学 | 237篇 |
力学 | 369篇 |
综合类 | 298篇 |
数学 | 679篇 |
物理学 | 2798篇 |
出版年
2024年 | 10篇 |
2023年 | 52篇 |
2022年 | 157篇 |
2021年 | 141篇 |
2020年 | 138篇 |
2019年 | 144篇 |
2018年 | 139篇 |
2017年 | 245篇 |
2016年 | 152篇 |
2015年 | 255篇 |
2014年 | 275篇 |
2013年 | 388篇 |
2012年 | 378篇 |
2011年 | 386篇 |
2010年 | 432篇 |
2009年 | 475篇 |
2008年 | 549篇 |
2007年 | 448篇 |
2006年 | 491篇 |
2005年 | 475篇 |
2004年 | 332篇 |
2003年 | 283篇 |
2002年 | 269篇 |
2001年 | 307篇 |
2000年 | 331篇 |
1999年 | 172篇 |
1998年 | 116篇 |
1997年 | 101篇 |
1996年 | 88篇 |
1995年 | 80篇 |
1994年 | 97篇 |
1993年 | 104篇 |
1992年 | 80篇 |
1991年 | 71篇 |
1990年 | 66篇 |
1989年 | 62篇 |
1988年 | 53篇 |
1987年 | 40篇 |
1986年 | 52篇 |
1985年 | 35篇 |
1984年 | 36篇 |
1983年 | 21篇 |
1982年 | 19篇 |
1981年 | 15篇 |
1980年 | 5篇 |
1979年 | 9篇 |
1978年 | 8篇 |
1977年 | 4篇 |
1971年 | 3篇 |
1965年 | 5篇 |
排序方式: 共有8605条查询结果,搜索用时 15 毫秒
1.
本文采用激光衍射法和光学显微计算机图像系统及自行开发的软件,测量了三个典型煤在快速加热初期燃烧、等温加热燃烧和火焰燃烧方式的颗粒尺寸,运用分数维理论,建立了煤燃烧颗粒破碎理论,实验和理论研究揭示了煤燃烧中颗粒尺寸变化的本质,理论计算和实验结果符合良好。 相似文献
2.
Based on the Dyson-Schwinger equations of QCD in the "rainbow" approximation, the fully dressed quarkpropagator Sf(p) is investigated, and then an algebraic parametrization form of the propagator is obtained as a solutionof the equations. The dressed quark amplitudes Af and Bf built up the fully dressed quark propagator and the dynamicalrunning masses Mf defined by Af and Bf for light quarks u, d and s are calculated, respectively. Using the predictedrunning masses Mf, quark condensates <0|q(0)q(0)|0> = -(0.255 GeV)a for u, d quarks, and <0|s s|0> = 0.8<0|q(0)q(0)]0)for s quark, and experimental pion decay constant fπ = 0.093 GeV, the masses of Goldstone bosons K, π, and η are alsoevaluated. The numerical results show that the masses of quarks are dependent on their momentum p2. The fully dressedquark amplitudes Af and Bf have correct behaviors which can be used for many purposes in our future researches onnonperturbative QCD. 相似文献
3.
应用密度矩阵方程计算了四能级原子系统中三阶非线性极化率随信号光和探针光频率失谐的变化关系。结果表明,由于量子干涉对信号光强度的敏感性,使四能级原子介质的交叉Kerr非线性作用大大增强,与三能级系统相比,四能级原子介质的Kerr非线性系数可增强两个数量级。 相似文献
4.
The microscopic theory of the blue phases of chiral liquid crystal is proposed. Beginning with the potential between two molecules, by using the cell model of liquid, applying statistical physical method, the distribution function and the free energy of the system are obtained. By using variational approach and zero-order approximation, the differential equation that the order parameter tensor of the blue phase can satisfy is obtained. Then we change the differential equation to the eigenequation problem in quantum mechanics. Considering the symmetry of the blue phases,the order parameter tensors of blue phases Ⅰ and Ⅱ can be made up of the eigenvectors. Our results are the same as the results of Ginzberg-Landau‘s phenomenological theory. The parameters in the order parameter tensors that we calculate in the located system are close to the predecessors‘ results. 相似文献
5.
A study on the ductile deformation domain of the brittle fault in the shallow level ofthe crust is a new probe field for the modern structural geology. Taking the southern Jiang-su Province area as an example the orientation measurement of quartz crystals, the com-positional texture observation of three pressure sensitive minerals and the rheological param-eter determination of dislocation densities, etc. have been demonstrated and analysed basedon typical samples in the present paper. In addition, their generation mechanisms arealso discussed from the cataclastic rheology, the dynamic differentiation and the simpleshearing, specially, from the Ode strength theory. Finally, a generative relationship betweenthe ductile deformation domain of the brittle fault system, in the regional layer--slip andthe formation of the stratabound ore deposit is shown as well. 相似文献
6.
7.
IntroductionCatal}ticrcactionsaffcctcdb}'diffosionaIlimitationincatal}'stporcshavcbccnextensive1}dcaltx`ithinlit.rat.rcll~5I.Scvcraltcchniqucsonthcspccialcase0fFischcr-Tropschs}'nthcsis(FTS)t\crcapplicdtocxplorcthebchaviorofthiscatal}ticrcactionundercxpcrimcntalandopcrationaIconditionsI3~5l.It`"ouldbeofvaluctoindicatchcrcthatthcseinvcstigationsx"ercmainl}'bascdonthesimplcstkineticsofthcfirstordcrinH2proposedbyAndersonl6]attheearIystages.However-thesetboents,striCtlyspeaking,areinvalidfor… 相似文献
8.
PengZHANG JiCunREN ZuoJunSHEN 《中国化学快报》2004,15(9):1091-1094
In this paper, we first presented a novel method for quantification of circulating DNA in human serum based on capillary zone electrophoresis with laser-induced fluorescence detection (CZE-LIF). The serum was digested by proteinase to release free DNA, and then CZE-LIF system was used for the quantification of total circulating DNA. This method was successfully used to quantify the circulating DNA levels in sera from healthy individuals and certain cancer patients.We found the significantly elevated circulating DNA levels in certain prostate cancer patients. Our results demonstrated that CZE-LIF system has good linearity, excellent sensitivity (0.5 ng/mL DNA),satisfactory reproducibility (RSDs in one day and between days were both less than 5%) and reliability, and is well suitable to the quantification of the circulating DNA in human serum or plasma. 相似文献
9.
一种液晶环氧树脂固化中扩散控制动力学研究 总被引:3,自引:0,他引:3
根据扩散控制反应的基本原理 ,建立了合适的反应模型 ,描述了 4 ,4′ 二 ( 2 ,3 环氧丙氧基 )偶氮苯(DGEAP) / 4,4′ 二氨基二苯甲烷 (DDM)环氧树脂的固化行为 .该模型认为 ,随着环氧基团反应程度的提高 ,基团的反应半径将受到影响 .当体系中出现了介晶基元的有序排列时 ,与之相连的反应基团的分布也受到影响 ,有序区内的局部浓度将变大 ,产生假浓度效应 ,并最终影响扩散控制反应动力学 .通过与普通环氧树脂固化动力学的比较 ,证实了这一效应 . 相似文献
10.