全文获取类型
收费全文 | 8619篇 |
免费 | 1292篇 |
国内免费 | 724篇 |
专业分类
化学 | 1421篇 |
晶体学 | 42篇 |
力学 | 661篇 |
综合类 | 89篇 |
数学 | 2169篇 |
物理学 | 2862篇 |
无线电 | 3391篇 |
出版年
2024年 | 35篇 |
2023年 | 120篇 |
2022年 | 193篇 |
2021年 | 269篇 |
2020年 | 294篇 |
2019年 | 262篇 |
2018年 | 272篇 |
2017年 | 341篇 |
2016年 | 398篇 |
2015年 | 333篇 |
2014年 | 542篇 |
2013年 | 763篇 |
2012年 | 564篇 |
2011年 | 544篇 |
2010年 | 429篇 |
2009年 | 467篇 |
2008年 | 555篇 |
2007年 | 519篇 |
2006年 | 478篇 |
2005年 | 423篇 |
2004年 | 379篇 |
2003年 | 353篇 |
2002年 | 304篇 |
2001年 | 283篇 |
2000年 | 231篇 |
1999年 | 196篇 |
1998年 | 197篇 |
1997年 | 147篇 |
1996年 | 144篇 |
1995年 | 113篇 |
1994年 | 85篇 |
1993年 | 65篇 |
1992年 | 59篇 |
1991年 | 38篇 |
1990年 | 37篇 |
1989年 | 38篇 |
1988年 | 30篇 |
1987年 | 13篇 |
1986年 | 16篇 |
1985年 | 19篇 |
1984年 | 16篇 |
1983年 | 5篇 |
1982年 | 20篇 |
1981年 | 17篇 |
1980年 | 6篇 |
1979年 | 6篇 |
1978年 | 5篇 |
1976年 | 3篇 |
1975年 | 4篇 |
1971年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
51.
Yoshiaki Yasuno Yasunori Sutoh Shuichi Makita Masahide Itoh Toyohiko Yatagai 《Optical Review》2003,10(5):498-500
A spectral interferometric optical coherence tomography (OCT) system which has polarization sensitivity is developed. This system reduces the mechanical scanning dimension by employing the principle of spectral interferometry, and measures a two dimensional cross-sectional image of biological tissue with one dimensional mechanical scanning. Sixteen OCT images with different polarization conditions are measured, and two dimensional distributions of each element of the Müller matrix of a sample to be measured are calculated. 相似文献
53.
54.
Monitoring Power Dissipation for Fault Detection 总被引:1,自引:0,他引:1
Bapiraju Vinnakota 《Journal of Electronic Testing》1997,11(2):173-181
In this paper, we suggest that the dynamic power dissipation of acircuit can be used for fault detection. Even those faults which do notaffect static power dissipation can be detected by monitoring dynamic powerdissipation. We discuss how stuck-at, stuck-open, and redundant faults maybe detected by monitoring dynamic power dissipation. In many cases, theFourier spectra of the supply currents in the good and faulty circuits willalso be very different. Further, specific tests can be applied so as toimprove fault coverage. Power monitoring is verified using simulation, andalso experimentally, for example circuits. 相似文献
55.
56.
Xiugui LIU Xiangjun WANG Department of Mathematics LPMC Nankai University Tianjin China. 《数学年刊B辑(英文版)》2006,(3)
This paper computes the Thorn map onγ2 and proves that it is represented by 2b2,0h1,2 in the ASS. The authors also compute the higher May differential of 62,0, from which it is proved thatγs(b0hn-h1bn-1) for 2≤s < p - 1 are permanent cycles in the ASS. 相似文献
57.
THE LARGE TIME BEHAVIOR OF SPECTRAL APPROXIMATION FOR A CLASS OF PSEUDOPARABOLIC VISCOUS DIFFUSION EQUATION 总被引:1,自引:0,他引:1
尚亚东 《数学物理学报(B辑英文版)》2007,27(1):153-168
The asymptotic behavior of the solutions to a class of pseudoparabolic viscous diffusion equation with periodic initial condition is studied by using the spectral method. The semidiscrete Fourier approximate solution of the problem is constructed and the error estiation between spectral approximate solution and exact solution on large time is also obtained. The existence of the approximate attractor AN and the upper semicontinuity d(AN,A)→0 are proved. 相似文献
58.
The subject of spectral distribution methods where one derives and applies the locally smoothed forms of observables in nuclei
is briefly reviewed. It is well understood that the local forms (with respect to energy) of the level density function, expectation
values and strength densities are Gaussian, linear (or ratio of Gaussians) and a bivariate Gaussian respectively. To accomodate
symmetries in the above forms, one has to deal with multivariate distributions in general; for example the angular-momentum
(J) decomposition leads to a bivariate Gaussian form for the level density. These results extend to indefinitely large spaces
by method of partitioning and they generate convolution forms. The origin of these remarkable spectral properties is discussed
and shell model examples are given to substantiate their applicability to nuclear systems. Spectral distribution theory is
a practical, usable theory because the smoothed forms are defined in terms of traces of low particle-rank operators, and the
trace information propagates. Finally we discuss the application of the spectral methods for a wide range of nuclear problems;
these include binding energies, orbit occupancies, electromagnetic andβ-decay sum rule quantities, analysis of operators, symmetry breaking, numerical level densities, and determination of bounds
on time-reversal non-invariant part of nucleon-nucleon interaction. 相似文献
59.
Mathematical Notes - 相似文献
60.