全文获取类型
收费全文 | 10550篇 |
免费 | 312篇 |
国内免费 | 33篇 |
专业分类
化学 | 7813篇 |
晶体学 | 30篇 |
力学 | 162篇 |
综合类 | 3篇 |
数学 | 1799篇 |
物理学 | 1088篇 |
出版年
2020年 | 138篇 |
2019年 | 104篇 |
2018年 | 80篇 |
2017年 | 83篇 |
2016年 | 196篇 |
2015年 | 198篇 |
2014年 | 188篇 |
2013年 | 355篇 |
2012年 | 407篇 |
2011年 | 463篇 |
2010年 | 339篇 |
2009年 | 285篇 |
2008年 | 461篇 |
2007年 | 449篇 |
2006年 | 472篇 |
2005年 | 444篇 |
2004年 | 381篇 |
2003年 | 326篇 |
2002年 | 337篇 |
2001年 | 235篇 |
2000年 | 168篇 |
1999年 | 150篇 |
1998年 | 183篇 |
1997年 | 141篇 |
1996年 | 140篇 |
1995年 | 145篇 |
1994年 | 137篇 |
1993年 | 179篇 |
1992年 | 128篇 |
1991年 | 119篇 |
1990年 | 107篇 |
1989年 | 130篇 |
1988年 | 128篇 |
1987年 | 164篇 |
1986年 | 150篇 |
1985年 | 175篇 |
1984年 | 180篇 |
1983年 | 153篇 |
1982年 | 140篇 |
1981年 | 152篇 |
1980年 | 148篇 |
1979年 | 155篇 |
1978年 | 139篇 |
1977年 | 122篇 |
1976年 | 140篇 |
1975年 | 92篇 |
1974年 | 88篇 |
1973年 | 92篇 |
1971年 | 80篇 |
1970年 | 72篇 |
排序方式: 共有10000条查询结果,搜索用时 125 毫秒
81.
H. Günther M. Foerste M. Kunze G. zu Putlitz U. von Stein 《Zeitschrift für Physik B Condensed Matter》1996,100(4):613-617
We review the previous conclusion [J.Y. Ryu, Y.C. Chung and S.D. Choi, Phys. Rev. B 32, 7769 (1984)] that the trace property Tr(ABC) = Tr(CAB) leads to two different cyclotron transition absorption formulae in the electron-phonon systems in the lowest order approximation. The pictorial expression and the calculated linewidths in Ge and Si show that the socalled EWC scheme is more seeming than the socalled MWC scheme. The difference is expected to disappear if we take into account all the higher order perturbation terms or start with the many body formalism in the complete scheme. 相似文献
82.
83.
84.
Hans-Christian Stolzenberg Gunther Kalnowski Wolfgang Dott 《Photochemistry and photobiology》1995,61(6):627-631
A new integrated system for reproducible, automated mechanical stimulation and measurement of bioluminescence (BL) in multiple samples of marine dinoflagellate cell suspensions is described. The system was designed to allow the application of standardized experimental routines to parallel test vials for the purpose of toxicity testing. A sample tray delivered test vials to the position of mechanical stimulation and BL measurement. Mechanical stimulation of BL was applied as sharp rotation-onset of the test vial about its vertical axis. Thus, any direct chemical or physical perturbation of the cell suspension was avoided. A silicon photovoltaic cell measured the emitted light. Stimulation, measurement and recording of BL were integrated and controlled by specially developed software, which runs on a personal computer in the graphic environment of MS-Windows. Precise scheduling, flexible programming and identical repetition of experimental routines are possible in practice. For Gonyaulax polyedra, details of BL, as stimulated and measured with the new system, are presented and discussed. We conclude that the system exhibits specific features that offer wide potential of application in several fields of research on dinoflagellate BL, particularly for toxicity testing. 相似文献
85.
86.
87.
The synthesis of various N-1 substituted ethyl 4-pyrazolecarboxylates via reaction of ethyl 2-formyl-3-oxo-propionate (= ethoxycarbonylmalondialdehyde) with appropriately substituted hydrazines is described. Moreover, detailed nmr-spectroscopic investigations with the title compounds are presented. 相似文献
88.
The present study aims at antimicrobial polyethylene surfaces. To achieve this, LLDPE was compounded with the polymeric biocide poly(2-tert-butylaminoethyl) methacrylate TBAM (bulk modification with 1.5-5.0 wt.% of TBAM). Surfaces of these polymer compounds were then subjected to microbial assays. Using standard methods the colony forming units (CFU) for Escherichia coli and Staphylococcus aureus were determined on these surfaces. In all cases, polyethylene surfaces with highly antimicrobial properties were achieved. An average reduction of 104 CFU ml−1 compared to neat LLDPE was achieved. The surfaces of these LLDPE/TBAM compounds were assessed by electrokinetic (zeta potential) measurements. The results indicate a relation between the antimicrobial activity and the zeta-potential of the polymer compounds. Moreover, the antimicrobial compounds were investigated towards biofilm formation. Compared to pristine LLDPE, the surfaces of the polymer compounds showed less adhering biofilm after a testing period of 16 weeks. 相似文献
89.
Wolfgang Rother 《manuscripta mathematica》1989,65(4):413-426
We consider the semilinear eigenvalue problem
on N (N 2) (N2) and investigate the question under which conditions on the radially symmetric function q, =0 is a bifurcation point for this equation in H1, In H2 and in Lp for 2p+. 相似文献
90.