全文获取类型
收费全文 | 97226篇 |
免费 | 2477篇 |
国内免费 | 2363篇 |
专业分类
化学 | 39572篇 |
晶体学 | 1105篇 |
力学 | 7324篇 |
综合类 | 152篇 |
数学 | 33782篇 |
物理学 | 20131篇 |
出版年
2023年 | 211篇 |
2022年 | 533篇 |
2021年 | 560篇 |
2020年 | 563篇 |
2019年 | 617篇 |
2018年 | 10809篇 |
2017年 | 10686篇 |
2016年 | 6784篇 |
2015年 | 1672篇 |
2014年 | 1321篇 |
2013年 | 1690篇 |
2012年 | 5368篇 |
2011年 | 12157篇 |
2010年 | 6858篇 |
2009年 | 7154篇 |
2008年 | 8044篇 |
2007年 | 9972篇 |
2006年 | 1457篇 |
2005年 | 2358篇 |
2004年 | 2404篇 |
2003年 | 2692篇 |
2002年 | 1782篇 |
2001年 | 750篇 |
2000年 | 671篇 |
1999年 | 459篇 |
1998年 | 415篇 |
1997年 | 307篇 |
1996年 | 383篇 |
1995年 | 263篇 |
1994年 | 204篇 |
1993年 | 208篇 |
1992年 | 144篇 |
1991年 | 160篇 |
1990年 | 130篇 |
1989年 | 136篇 |
1988年 | 108篇 |
1987年 | 109篇 |
1986年 | 98篇 |
1985年 | 114篇 |
1984年 | 87篇 |
1983年 | 68篇 |
1982年 | 74篇 |
1981年 | 72篇 |
1980年 | 73篇 |
1979年 | 79篇 |
1978年 | 60篇 |
1977年 | 47篇 |
1976年 | 46篇 |
1973年 | 54篇 |
1914年 | 46篇 |
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
881.
882.
883.
Gur Mosheiov 《The Journal of the Operational Research Society》1996,47(9):1184-1191
We study a problem of scheduling deteriorating jobs, i.e. jobs whose processing times are an increasing function of their starting times. We consider the case of a single machine and linear job-independent deterioration. The objective is to minimize the sum of weighted completion times, with weights proportional to the basic processing times. The optimal schedule is shown to be Λ-shaped, i.e. the sequence of the basic processing times has a single local maximum. Moreover, we show that the problem is solved in O(N log N) time. In the last section we test heuristics for the case of general weights. 相似文献
884.
For any -complexes and , we show that . We use this fact to compute generalized evaluation subgroups of generalized tori relative to a sphere.
885.
Anthony PL Arnold RG Band HR Borel H Bosted PE Breton V Cates GD Chupp TE Dietrich FS Dunne J Erbacher R Fellbaum J Fonvieille H Gearhart R Holmes R Hughes EW Johnson JR Kawall D Keppel C Kuhn SE Lombard-Nelsen RM Marroncle J Maruyama T Meyer W Meziani Z Middleton H Morgenstern J Newbury NR Petratos GG Pitthan R Prepost R Roblin Y Rock SE Rokni SH Shapiro G Smith T Souder PA Spengos M Staley F Stuart LM Szalata ZM Terrien Y Thompson AK White JL Woods M Xu J Young CC Zapalac G 《Physical review D: Particles and fields》1996,54(11):6620-6650
886.
Gerhard Hasslinger Erik S. Rieger 《The Journal of the Operational Research Society》1996,47(5):640-653
This paper deals with approximate analysis methods for open queueing networks. External and internal flows from and to the nodes are characterized by renewal processes with discrete time distributions of their interarrival times. Stationary distributions of the waiting time, the queue size and the interdeparture times are obtained using efficient discrete time algorithms for single server (GI/G/1) and multi-server (GI/D/c) nodes with deterministic service. The network analysis is extended to semi-Markovian representations of each flow among the nodes, which include parameters of the autocorrelation function. 相似文献
887.
Steve PhillipsJr. 《The Journal of the Operational Research Society》1996,47(5):697-701
The paper presents an application oriented procedure for solving the project management duration/resource tradeoff problem. A procedure is presented for reducing a project from a normal to a crash duration state at a minimum amount of additional resource expenditure assuming a linear utilization functions. The procedure is network based using a graphical Cut Search Approach to locate the minimal resource level at each reduction in total project duration. Activity-on-arc networks and flow networks are utilized. The paper is presented for practical application and for conceptual development as compared to a theoretical treatment. 相似文献
888.
889.
Krishna S Kumar 《Pramana》1993,41(1):45-53
We report on two sensitive tests of lepton universality carried out by the 4 LEP experiments at the Z0 pole. From measurements of the τ polarization in e+ e?→τ + τ ?, the ratios of the vector and axial vector coupling constants of the electron and the tau lepton to the weak neutral current are obtained to beg v e /g a e =0.066±0.015 andg V τ /g A τ =0.070±0.009 respectively. From measurement of the τ lifetime and the τ leptonic branching ratios, the ratio of the coupling constants describing weak leptonic decays of the τ and the μ is measured to beG τ /G μ =0.996±0.008. 相似文献
890.
A review is given of the StandardSU(5) supergravity model. This model has passed an important check regarding unification of the electro-weak and the strong couplings using high precision LEP data. It is shown that for a significant domain of the parameter space the model also satisfies constraints on the SUSY spectrum from CDF and LEP, as well as proton stability and cosmological relic density constraints. 相似文献