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81.
In this paper the gain characteristics of two-pump fiber optical parametric amplifiers (FOPA) with two-section highly nonlinear fibers are analyzed numerically and the parameters of the fibers are optimized to reach broad and flat gain spectra using genetic algorithm. Different from the previous methods, here the space between two pump wavelengths and the parameter β4 of the fibers are included as a pivotal factor in the optimization. The numerical simulation shows that using two-section practical high nonlinear fibers, the amplifier may reach 110 nm bandwidth covering 1495–1605 nm with 10.5 dB average gain and gain ripple of 0.17 dB, when the total pump power is 1 W. 相似文献
82.
Ghahraman Solookinejad Amir Sayid Hassan RozatianMohammad Hossein Habibi 《Applied Surface Science》2011,258(1):260-264
Zinc oxide (ZnO) thin film was fabricated by sol-gel spin coating method on glass substrate. X-ray reflectivity (XRR) and its optimization have been used for characterization and extracting physical parameters of the film. Genetic algorithm (GA) has been applied for this optimization process. The model independent information was needed to establish data analyzing process for X-ray reflectivity before optimization process. Independent information was exploited from Fourier transform of Fresnel reflectivity normalized X-ray reflectivity. This Fourier transformation (Auto Correlation Function) yields thickness of each coated layer on substrate. This information is a keynote for constructing optimization process. Specular X-ray reflectivity optimization yields structural parameters such as thickness, roughness of surface and interface and electron density profile of the film. Acceptable agreement exists between results obtained from Fourier transformation and X-ray reflectivity fitting. 相似文献
83.
A new predictor-corrector algorithm is proposed for solvingP
*(κ)-matrix linear complementarity problems. If the problem is solvable, then the algorithm converges from an arbitrary positive
starting point (x
0,s
0). The computational complexity of the algorithm depends on the quality of the starting point. If the starting point is feasible
or close to being feasible, it has
-iteration complexity, whereρ
0 is the ratio of the smallest and average coordinate ofX
0
s
0. With appropriate initialization, a modified version of the algorithm terminates in O((1+κ)2(n/ρ
0)L) steps either by finding a solution or by determining that the problem has no solution in a predetermined, arbitrarily large,
region. The algorithm is quadratically convergent for problems having a strictly complementary solution. We also propose an
extension of a recent algorithm of Mizuno toP
*(κ)-matrix linear complementarity problems such that it can start from arbitrary positive points and has superlinear convergence
without a strictly complementary condition.
The work of this author was supported in part by NSF, Grant DMS 9305760 and by an Oberman fellowship from the University of
Iowa Center for Advanced Studies. 相似文献
84.
A. J. W. Duijvestijn 《BIT Numerical Mathematics》1972,12(3):318-324
The correctness of an in-place permutation algorithm is proved. The algorithm exchanges elements belonging to a permutation cycle. A suitable assertion is constructed from which the correctness can be deduced after completion of the algorithm.An in-place rectangular matrix transposition algorithm is given as an example. 相似文献
85.
Set to set broadcasting in communication networks 总被引:1,自引:0,他引:1
Suppose G = (V,E) is a graph whose vertices represent people and edges represent telephone lines between pairs of people. Each person knows a unique message and is ignorant of the messages of other people at the beginning. These messages are then spread by telephone calls. In each call, two people exchange all information they have so far in exactly one unit of time. Suppose A and B are two nonempty subsets of V. The main purpose of this paper is to study the minimum number b(A,B,G) of telephone calls by which A broadcasts to B; and the minimum time t(A,B,G) such that A broadcasts to B. In particular, we give an exact formula for b(A,B,Kn) and linear-time algorithms for computing b(A,B,T) and t(A,B,T) of a tree T. 相似文献
86.
Jennifer S.K. Chan Anthony Y.C. Kuk Carrie H.K. Yam 《Journal of multivariate analysis》2005,94(2):300-312
Geyer (J. Roy. Statist. Soc. 56 (1994) 291) proposed Monte Carlo method to approximate the whole likelihood function. His method is limited to choosing a proper reference point. We attempt to improve the method by assigning some prior information to the parameters and using the Gibbs output to evaluate the marginal likelihood and its derivatives through a Monte Carlo approximation. Vague priors are assigned to the parameters as well as the random effects within the Bayesian framework to represent a non-informative setting. Then the maximum likelihood estimates are obtained through the Newton Raphson method. Thus, out method serves as a bridge between Bayesian and classical approaches. The method is illustrated by analyzing the famous salamander mating data by generalized linear mixed models. 相似文献
87.
Raymond H. Chan Michael K. Ng Robert J. Plemmons 《Numerical Linear Algebra with Applications》1996,3(1):45-64
In this paper, we propose a method to generalize Strang's circulant preconditioner for arbitrary n-by-n matrices An. The th column of our circulant preconditioner Sn is equal to the th column of the given matrix An. Thus if An is a square Toeplitz matrix, then Sn is just the Strang circulant preconditioner. When Sn is not Hermitian, our circulant preconditioner can be defined as . This construction is similar to the forward-backward projection method used in constructing preconditioners for tomographic inversion problems in medical imaging. We show that if the matrix An has decaying coefficients away from the main diagonal, then is a good preconditioner for An. Comparisons of our preconditioner with other circulant-based preconditioners are carried out for some 1-D Toeplitz least squares problems: min ∥ b - Ax∥2. Preliminary numerical results show that our preconditioner performs quite well, in comparison to other circulant preconditioners. Promising test results are also reported for a 2-D deconvolution problem arising in ground-based atmospheric imaging. 相似文献
88.
两个可解的2×n自由作业排序问题 总被引:1,自引:0,他引:1
本文考虑将n个互相独立的每道工序加工时长相等的工件放在两台机器上加工的自由作业排序问题。讨论了目标函数分别是带权完工时间和(O2/UET/Σwici)及最大迟后(O2/UET/Lmax)两个问题,分别得到了计算时间限为O(nlogn)及O(n2)的两个求解最优时间表的多项式算法。 相似文献
89.
In developing a new method to measure the phase distribution of a light wave utilizing the adaptive control of the pupil function with a liquid crystal panel, the optimization procedure for the adaptive control is shown to improve when a local algorithm is adopted. The feasibility of the proposed system is confirmed by computer simulation as well as by some basic experiments. 相似文献
90.
When a positive integer is expressed as a sum of squares, with each successive summand as large as possible, the summands decrease rapidly in size until the very end, where one may find two 's, or several 's. We find that the set of integers for which the summands are distinct does not have a natural density but that the counting function oscillates in a predictable way.