全文获取类型
收费全文 | 20787篇 |
免费 | 2892篇 |
国内免费 | 1457篇 |
专业分类
化学 | 5285篇 |
晶体学 | 272篇 |
力学 | 2685篇 |
综合类 | 167篇 |
数学 | 4363篇 |
物理学 | 12364篇 |
出版年
2024年 | 21篇 |
2023年 | 136篇 |
2022年 | 306篇 |
2021年 | 364篇 |
2020年 | 427篇 |
2019年 | 400篇 |
2018年 | 383篇 |
2017年 | 634篇 |
2016年 | 680篇 |
2015年 | 680篇 |
2014年 | 920篇 |
2013年 | 1913篇 |
2012年 | 1084篇 |
2011年 | 1318篇 |
2010年 | 1032篇 |
2009年 | 1630篇 |
2008年 | 1658篇 |
2007年 | 1526篇 |
2006年 | 1375篇 |
2005年 | 1021篇 |
2004年 | 921篇 |
2003年 | 853篇 |
2002年 | 781篇 |
2001年 | 703篇 |
2000年 | 587篇 |
1999年 | 492篇 |
1998年 | 531篇 |
1997年 | 420篇 |
1996年 | 333篇 |
1995年 | 290篇 |
1994年 | 250篇 |
1993年 | 227篇 |
1992年 | 179篇 |
1991年 | 155篇 |
1990年 | 118篇 |
1989年 | 109篇 |
1988年 | 115篇 |
1987年 | 82篇 |
1986年 | 69篇 |
1985年 | 71篇 |
1984年 | 69篇 |
1983年 | 34篇 |
1982年 | 62篇 |
1981年 | 41篇 |
1980年 | 19篇 |
1979年 | 33篇 |
1978年 | 17篇 |
1977年 | 16篇 |
1976年 | 16篇 |
1973年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 351 毫秒
61.
Summary Excessive breakdown of elastin, a structural protein, may be related to aortic disease and emphysema. Since L-valyl-L-proline occurs in high concentrations in elastin, a rapid and sensitive method using HPLC with post-column on-line derivatization was used to measure the dipeptide from swine aortic tissue, and the amount of elastin present was determined. Elastin was extracted by alkaline hydrolysis. After neutralization and filtration, the sample was injected onto a ODS-2 gel column, and the dipeptide was eluted by a linear gradient of 0 to 10% of 1-propanol in 50 mM heptafluorobutyrate, pH 3, at a flow rate of 1 ml/min. The eluent was reacted with fluorescamine at pH 8.6, and fluorescence was detected at an excitation wavelength of 395 nm and a 455 nm cutoff emission filter.Presented at the 17th International Symposium on Chromatography, September 25–30, 1988, Vienna, Austria. 相似文献
62.
FJZ-250型高速分幅相机时间测量不确定度分析 总被引:2,自引:1,他引:1
FJZ-250型高速转镜分幅相机因转镜速度的不可重复性,光机结构的构造原理和控制系统各路高压触发时间的漂移,导致了时间测量的不确定度。为此,须对相机测量数据进行校正。阐述了校正方法、提供了逐幅校正位置误差的修正系数。若以预置转速对应的名义周期值去处理测量结果,则相机的时间测量合成小确定度将达1%,对名义周期值和名义幅间间隔时间值进行修正后,则可降至0.3%。 相似文献
63.
A. B. Mitkevich 《Mechanics of Composite Materials》2005,41(6):497-504
Errors in the programs of winding pressure vessels can lead to an asymmetric reinforcement structure, which affects the equilibrium
shape of their domes and the tension in the left and right families of filaments. In this paper, equations determining the
equilibrium shape of the domes, the tension in filaments, and the shear stresses between layers are obtained. Examples with
winding trajectories in the form of geodesics and constant-deviation lines are considered. It is found that, for pressure
vessels, in the absence of external torque, the tension levels in filaments of the left and right families differ considerably.
It is also revealed that, for actual friction coefficients in winding, the shear stresses taken up by the binder are insignificant.
__________
Translated from Mekhanika Kompozitnykh Materialov, Vol. 41, No. 6, pp. 743–752, November–December, 2005. 相似文献
64.
Andrey Pereverzev 《Foundations of Physics Letters》2003,16(5):411-428
We argue that it may be possible to consistently explain the quantum measurement by assuming that the wave function is in one-to-one correspondence with objective physical reality and has no probabilistic interpretation. In the context of such approach we consider the model of a harmonic oscillator linearly coupled to a heat bath and treat the oscillator as the system being measured. Three classes of initial pure states for the bath are considered. Exact expressions for the average values and variances of the oscillator coordinate and momentum as functions of time are considered for each class of pure states. It is shown that these quantities exhibit different asymptotic behavior for different classes of initial states of the bath. In particular, if each mode of the bath is initially in a coherent state, then for an arbitrary initial state of the oscillator the variances of the oscillator coordinate and momentum asymptotically approach the same values as for a coherent state of the free oscillator, while the averages of coordinate and momentum show a Brownian-like behavior. We argue that such behavior shows several features of the quantum measurement and supports our interpretation of the wave function. 相似文献
65.
A time discrete scheme is used to approximate the solution toa phase field system of PenroseFife type with a non-conservedorder parameter. An a posteriori error estimate is presentedthat allows the estimation of the difference between continuousand semidiscrete solutions by quantities that can be calculatedfrom the approximation and given data. 相似文献
66.
Alessandro Conflitti 《Finite Fields and Their Applications》2003,9(4):423-431
We propose a probabilistic algorithm to reduce computing the greatest common divisor of m polynomials over a finite field (which requires computing m−1 pairwise greatest common divisors) to computing the greatest common divisor of two polynomials over the same field. 相似文献
67.
林正炎 《数学物理学报(B辑英文版)》2003,23(3)
Let {X_n, n≥1} be a strictly stationary sequence of random variables, whichare either associated or negatively associated, f(·) be their common density. In this paper,the author shows a central limit theorem for a kernel estimate of f(·) under certain regularconditions. 相似文献
68.
网络股泡沫大小测度研究 总被引:1,自引:0,他引:1
网络股泡沫是最能反映网络泡沫本质的表现形式,本文利用理性预期理论,构建了网络股泡沫大小的测度模型,说明网络股泡沫的存在,在此基础上确定了网络股泡沫大小的测度指标,并以雅虎公司股票为例对泡沫的大小进行了测度,结果符合网络泡沫的实际情况。 相似文献
69.
A locally convex space is said to be a Gateaux differentiability space (GDS)provided every continuous convex function defined on a nonempty convex open subset D of the space is densely Gateaux differentiable in D.This paper shows that the product of a GDS and a family of separable Frechet spaces is a GDS,and that the product of a GDS and an arbitrary locally convex space endowed with the weak topology is a GDS. 相似文献
70.