全文获取类型
收费全文 | 3417篇 |
免费 | 123篇 |
国内免费 | 14篇 |
专业分类
化学 | 2209篇 |
晶体学 | 20篇 |
力学 | 121篇 |
数学 | 673篇 |
物理学 | 531篇 |
出版年
2023年 | 17篇 |
2022年 | 61篇 |
2021年 | 87篇 |
2020年 | 36篇 |
2019年 | 74篇 |
2018年 | 48篇 |
2017年 | 69篇 |
2016年 | 114篇 |
2015年 | 103篇 |
2014年 | 94篇 |
2013年 | 207篇 |
2012年 | 192篇 |
2011年 | 207篇 |
2010年 | 124篇 |
2009年 | 113篇 |
2008年 | 205篇 |
2007年 | 169篇 |
2006年 | 196篇 |
2005年 | 170篇 |
2004年 | 122篇 |
2003年 | 129篇 |
2002年 | 89篇 |
2001年 | 50篇 |
2000年 | 43篇 |
1999年 | 46篇 |
1998年 | 32篇 |
1997年 | 34篇 |
1996年 | 45篇 |
1995年 | 39篇 |
1994年 | 36篇 |
1993年 | 41篇 |
1992年 | 30篇 |
1991年 | 20篇 |
1990年 | 22篇 |
1989年 | 20篇 |
1988年 | 19篇 |
1987年 | 22篇 |
1986年 | 17篇 |
1985年 | 42篇 |
1984年 | 36篇 |
1983年 | 41篇 |
1982年 | 29篇 |
1981年 | 23篇 |
1980年 | 31篇 |
1979年 | 24篇 |
1977年 | 24篇 |
1976年 | 18篇 |
1975年 | 18篇 |
1974年 | 13篇 |
1973年 | 15篇 |
排序方式: 共有3554条查询结果,搜索用时 484 毫秒
971.
JPC – Journal of Planar Chromatography – Modern TLC - 相似文献
972.
973.
Mario Thevis Simon Beuck Andreas Thomas Gregor Fußhöller Gerg Sigmund Nils Schlörer Grigory Rodchenkov Mathias Schäfer Wilhelm Schänzer 《Rapid communications in mass spectrometry : RCM》2009,23(15):2363-2370
New insights into the biochemistry of cardiac arrhythmia and skeletal muscle fatigue have yielded new drug candidates to counteract these phenomena. Major biological targets have become ryanodine receptor (RyR)‐based Ca2+‐release channels, which tend to ‘leak’ under various circumstances including strenuous exercise and, thus, cause aberrant calcium sparks that entail impaired muscle function. Therapeutics, which are referred to as rycals, are currently being developed to treat cardiac arrhythmia via enhancement of calstabin‐ryanodine affinities that causes a stabilization of the RyR. These therapeutics possess potential for misuse in sports, and an early implementation of target analytes such as the benzothiazepine derivatives S‐107 and JTV‐519 or putative metabolites into doping control screening procedures is recommended. Reference compounds, deuterated analogues, and a putative metabolic product were synthesized, and electron ionization mass spectra of these products were studied and dissociation pathways elucidated by means of tandem mass spectrometry (MS/MS) and accurate mass measurements. The characterized analytes were incorporated into existing sports drug testing assays based on liquid‐liquid extraction and subsequent gas chromatography/mass spectrometry (GC/MS) analysis, and specificity, lower limit of detection (4–6 ng/mL), intraday and interday precision (1.5–17.2%), as well as recovery (63–66%) were determined. The established procedure proved suitable for routine doping control analysis to detect a potential misuse of the drug candidate S‐107 in elite sport. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
974.
We define a notion of an asymptotic upper curvature bound for Gromov hyperbolic metric spaces that is invariant under rough-isometries
and examine the basic properties of this concept.
M.B. was supported by NSF grants DMS 0200566 and DMS 0244421. Th.F. was supported by the Deutsche Forschungsgemeinschaft (FO
353/1-1). 相似文献
975.
Mario Calonghi 《Annali di Matematica Pura ed Applicata》1934,13(1):171-189
Sunto L'A. tratta della curvatura media e relativa di una varietà in ambienti riemanniani: poste in luce notevoli disuguaglianze
e una nuova definizione della curvatura media, introduce unavarietà centrale ed unaquadrica di curvatura associate ad ogni punto della varietà e ne dà proprietà notevoli. 相似文献
976.
A quantum Ising-like spin-j model, characterized by arbitrary multipole-multipole interactions as well as external fields, is proposed and analyzed. A thorough discussion of the algebraic properties of the dynamical variables (which belong to SU(2j+1)) is performed, whereby by the application of an improved version of the mean-field theory (which has the usual mean-field theory as its zeroeth order approximation) an explicit expression for the free energy is derived. 相似文献
977.
A holomorphic functionf defined on the unit disk d is called a Bloch function provided {fx73-02} For α ∃ (0,1] letB∞(α)denote the class of locally univalent Bloch functionsf normalized by ∥f∥B ≤1f(0) = 0 andf’(0) = α. A type of subordination theorem is established for B∞(α). This subordination theorem is used to derive sharp growth,
distortion, curvature and covering theorems for B∞(α).
Supported as a Feodor Lynen Fellow of the Alexander von Humboldt Foundation.
Research supported in part by a National Science Foundation grant. 相似文献
978.
The introduction of various new radiofrequency electrical discharges has placed increased emphasis on circuit design which provides optimal energy transfer between a generator and its corresponding spectroscopic “load”. This technology is well developed for high-frequency (ca. 27 MHz) inductively-coupled plasma discharges and for cavity discharges which operate in the microwave region (e.g., 2450 MHz). The 200-MHz very high frequency (VHF) region has received less attention. New circuitry is described which allows effective transfer of high power (5-kW), pulsed (2.5-μs), VHF (200-MHz) energy into a plasma suitable for analytical purposes. A triple-stub tuner is used in this circuitry. Comparison with other approaches and applicability to a variety of discharge systems are discussed. 相似文献
979.