全文获取类型
收费全文 | 2688篇 |
免费 | 89篇 |
国内免费 | 8篇 |
专业分类
化学 | 1652篇 |
晶体学 | 38篇 |
力学 | 95篇 |
数学 | 295篇 |
物理学 | 705篇 |
出版年
2023年 | 16篇 |
2022年 | 45篇 |
2021年 | 53篇 |
2020年 | 50篇 |
2019年 | 64篇 |
2018年 | 57篇 |
2017年 | 42篇 |
2016年 | 92篇 |
2015年 | 73篇 |
2014年 | 82篇 |
2013年 | 174篇 |
2012年 | 189篇 |
2011年 | 174篇 |
2010年 | 121篇 |
2009年 | 88篇 |
2008年 | 152篇 |
2007年 | 157篇 |
2006年 | 135篇 |
2005年 | 115篇 |
2004年 | 91篇 |
2003年 | 91篇 |
2002年 | 78篇 |
2001年 | 30篇 |
2000年 | 35篇 |
1999年 | 22篇 |
1998年 | 27篇 |
1997年 | 24篇 |
1996年 | 21篇 |
1995年 | 22篇 |
1994年 | 18篇 |
1993年 | 24篇 |
1992年 | 15篇 |
1991年 | 13篇 |
1990年 | 16篇 |
1989年 | 26篇 |
1988年 | 12篇 |
1987年 | 29篇 |
1986年 | 15篇 |
1985年 | 26篇 |
1984年 | 23篇 |
1983年 | 20篇 |
1982年 | 16篇 |
1981年 | 19篇 |
1980年 | 21篇 |
1979年 | 17篇 |
1978年 | 17篇 |
1977年 | 16篇 |
1976年 | 13篇 |
1975年 | 13篇 |
1973年 | 11篇 |
排序方式: 共有2785条查询结果,搜索用时 15 毫秒
1.
Milan V. Patel Samir A. Patel Arabinda Ray Rajni M. Patel 《Journal of polymer science. Part A, Polymer chemistry》2004,42(20):5227-5234
Copolymers of monomers 2,4‐dichlorophenyl methacrylate (2,4‐DMA) and methyl methacrylate (MMA) were synthesized with different monomer feed ratios using toluene as a solvent and 2,2′‐azobisisobutyronitrile (AIBN) as an initiator at 70 °C. The copolymers were characterized by IR‐spectroscopy, and copolymer composition was determined with UV‐spectroscopy. The linearization method of Fineman–Ross was employed to obtain the monomer reactivity ratios. The molecular weights and polydispersity indexes were determined by gel permeation chromatography (GPC). Thermogravimetric analyses of polymers were carried out in nitrogen atmosphere. The homo‐ and copolymers were tested for their antimicrobial properties against selected microorganisms. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5227–5234, 2004 相似文献
2.
A server needs to compute a broadcast schedule for n pages whose request times are known in advance. Outputting a page satisfies all outstanding requests for the page. The goal is to minimize the average waiting time of a client. In this paper, we show the equivalence of two apparently different relaxations that have been considered for this problem. 相似文献
3.
CV Tomy D Pal SS Banerjee S Ramakrishnan AK Grover S Bhattacharya MJ Higgins G Balakrishnan McK Paul 《Pramana》2002,58(5-6):925-935
The weakly pinned single crystals of the hexagonal 2H-NbSe2 compound have emerged as prototypes for determining and characterizing the phase boundaries of the possible order-disorder
transformations in the vortex matter. We present here a status report based on the ac and dc magnetization measurements of
the peak effect phenomenon in three crystals of 2H-NbSe2, in which the critical current densities vary over two orders of magnitude. We sketch the generic vortex phase diagram of
a weakly pinned superconductor, which also utilizes theoretical proposals. We also establish the connection between the metastability
effects and pinning. 相似文献
4.
Apurba Bhattacharya Nitin C. Patel Michael Peddicord Luca Parlanti John A. Grosso 《Tetrahedron letters》2006,47(30):5341-5343
An efficient, one-pot, phase transfer N-amination technology was developed. The protocol utilizes chloramine, an inexpensive and safe electrophilic aminating agent potentially viable for commercial manufacturing. 相似文献
5.
V Ravindran Pankaj Agrawal Rahul Basu Satyaki Bhattacharya J Blümlein V Del Duca R Harlander D Kosower Prakash Mathews Anurag Tripathi 《Pramana》2006,67(5):983-992
This is the report of the subgroup QCD of Working Group-4 at WHEPP-9. We present the activities that had taken place in the
subgroup and report some of the partial results arrived at following the discussion at the working group meetings. 相似文献
6.
Bilevel programming approach applied to the flow shop scheduling problem under fuzziness 总被引:1,自引:0,他引:1
Samir A. Abass 《Computational Management Science》2005,2(4):279-293
This paper presents a fuzzy bilevel programming approach to solve the flow shop scheduling problem. The problem considered
here differs from the standard form in that operators are assigned to the machines and imposing a hierarchy of two decision
makers with fuzzy processing times. The shop owner considered higher level and assigns the jobs to the machines in order to
minimize the flow time while the customer is the lower level and decides on a job schedule in order to minimize the makespan.
In this paper, we use the concepts of tolerance membership function at each level to define a fuzzy decision model for generating
optimal (satisfactory) solution for bilevel flow shop scheduling problem. A solution algorithm for solving this problem is
given.
Mathematics Subject Classification:
90C70, 90B36, 90C99 相似文献
7.
It is shown how the traditional method of neglecting the energy of acoustic phonons and approximating their distribution by the equipartition law leads to significant errors in the phonon growth rate in a many-valley model semiconductor when the lattice temperature is low. 相似文献
8.
We derive a fourth-order compact finite difference scheme for a two-dimensional elliptic problem with a mixed derivative and constant coefficients. We conduct experimental study on numerical solution of the problem discretized by the present compact scheme and the traditional second-order central difference scheme. We study the computed accuracy achieved by each scheme and the performance of the Gauss-Seidel iterative method, the preconditioned GMRES iterative method, and the multigrid method, for solving linear systems arising from the difference schemes. 相似文献
9.
Apurba Bhattacharya Nitin C. Patel Ritesh Tichkule Jiejun Wu 《Tetrahedron letters》2006,47(4):565-567
A simple, surfactant-mediated, one-pot, solvent-free dealkylative cleavage of aryl ethers and esters followed by subsequent optional trans-alkylation under essentially neutral conditions has been developed. 相似文献
10.
K. Vinay Kumar Reddy B. Sreenivasa Reddy M. Sreenath Reddy Ch. Gopal Reddy P. Yadagiri Reddy K. Rama Reddy 《Radiation measurements》2003,36(1-6):419-423
Studies conducted by Atomic Minerals Directorate of Exploration and Research (AMD) of Hyderabad, India had established the presence of higher concentrations of uranium in Lambapur and Peddagattu areas of Nalgonda district, AP, India and it was estimated that it could be a viable source for commercial extraction. The envisaged extraction process involves dispersion of radioactive particulate matter into atmosphere. Environmental radioactive studies in and around proposed mining areas at this point of time will be extremely useful for establishing base line data before a large scale uranium extraction process comes into existence. To this end, Solid State Nuclear Track Detectors were installed to evaluate indoor radon and thoron concentration levels in the dwellings of the area. The geometric means of radon and thoron concentration levels were found to be (7.1±0.2)×101 and (6.7±0.3)×101 Bq/m3, respectively. Simultaneously, natural background radiation measurements were also made and these levels are found to vary from 770 to 3995 μGy/y in the spatial distribution. 相似文献