全文获取类型
收费全文 | 1567篇 |
免费 | 66篇 |
国内免费 | 4篇 |
专业分类
化学 | 972篇 |
晶体学 | 13篇 |
力学 | 37篇 |
数学 | 188篇 |
物理学 | 427篇 |
出版年
2022年 | 14篇 |
2021年 | 20篇 |
2020年 | 39篇 |
2019年 | 27篇 |
2018年 | 11篇 |
2017年 | 16篇 |
2016年 | 36篇 |
2015年 | 37篇 |
2014年 | 34篇 |
2013年 | 60篇 |
2012年 | 98篇 |
2011年 | 96篇 |
2010年 | 65篇 |
2009年 | 41篇 |
2008年 | 89篇 |
2007年 | 75篇 |
2006年 | 71篇 |
2005年 | 55篇 |
2004年 | 55篇 |
2003年 | 51篇 |
2002年 | 42篇 |
2001年 | 38篇 |
2000年 | 28篇 |
1999年 | 21篇 |
1998年 | 24篇 |
1997年 | 10篇 |
1996年 | 32篇 |
1995年 | 20篇 |
1994年 | 17篇 |
1993年 | 24篇 |
1992年 | 30篇 |
1991年 | 32篇 |
1990年 | 19篇 |
1989年 | 18篇 |
1988年 | 18篇 |
1987年 | 13篇 |
1986年 | 16篇 |
1985年 | 21篇 |
1984年 | 12篇 |
1983年 | 12篇 |
1982年 | 8篇 |
1981年 | 9篇 |
1980年 | 10篇 |
1979年 | 8篇 |
1978年 | 18篇 |
1977年 | 12篇 |
1976年 | 9篇 |
1975年 | 14篇 |
1974年 | 20篇 |
1973年 | 13篇 |
排序方式: 共有1637条查询结果,搜索用时 15 毫秒
1.
Analytical and Bioanalytical Chemistry - 相似文献
2.
R. Hefelmann P. Mann A. Aignan F. Filsinger und H. Amsel 《Fresenius' Journal of Analytical Chemistry》1902,41(1):66-68
Ohne Zusammenfassung 相似文献
3.
Neutral Community Theory: How Stochasticity and Dispersal-Limitation Can Explain Species Coexistence
Neutral community theory explains biodiversity, i.e. the coexistence of several species, as the result of a stochastic balance
between immigration and extinction on a local level, and between speciation and extinction on a regional level. The most popular
model, presented by Hubbell in 2001, has seen many analytical developments in recent years, which can be used in model analysis,
model testing and model comparison. We review these developments here, and present alternative derivations and shine previously
unnoticed lights on them. 相似文献
4.
Intensity-dependent absorption of 25 ns excimer laser pulses in common UV-window materials was investigated. By employing a calorimetric technique which provides greatly enhanced sensitivity compared to transmissive measurements, two-photon absorption coefficients were determined at intensities of 2–80 MW/cm2 and found to be in good agreement with previous measurements at 10–100 GW/cm2. Also, color-center formation in fused silica was observed. It was possible to quantify transient and cumulative effects as a function of intensity. 相似文献
5.
Peroxyoxalate chemiluminescence may be used for sensitive postcolumn detection of phenothiazine analytes separated by high performance liquid chromatography with appropriate optimization of measurement conditions such as solvent, pH and oxalate ester. Detectability of fluorescent analytes by chemical excitation varies greatly, but analytes with low oxidation potentials are generally more readily detected at low levels, as demonstrated for phenothiazines, an important class of fluorescent drugs. Some improvement in detection limits is observed for fluphenazine when chemiluminescence detection is compared to conventional fluorescence detection. Because of the specificity of chemical excitation, fewer interferences from fluorescent impurities in a urine matrix are observed. 相似文献
6.
The lanthanide sulfotellurides (LS)2Te1+x (0 ≤ x < 0.50) show order-disorder phenomena. Above 450°C, they crystallize in a partially disordered structure, orthorhombic with cell parameters a, b, and c close to 4.1, 5.2, and 13.6 Å, respectively. This structure is determined from diffractometer data on a (HoS)2Te1.34 crystal (R = 0.061). It is built up along the c axis from (L4S) tetrahedra layers, separated by Te planes. Disorder and nonstoichiometry are related to the two vacant Te sites. 相似文献
7.
Etienne Sandier Itai Shafrir 《Calculus of Variations and Partial Differential Equations》1994,2(1):113-122
We study the uniqueness of minimizing harmonic maps to a closed hemisphere. We are able to describe the boundary data for which there are more than one minimizer, and to describe in these cases the corresponding set of minimizers. This is a limiting case for a former result of W.Jäger and H.Kaul.This article was processed by the author using the Springer-Verlag TEX PJourlg macro package 1991. 相似文献
8.
Ginette Ratovo Jean‐Pierre Souchard Pascale Urizzi Yvon Coulais Franoise Nepveu Etienne Hollande 《应用有机金属化学》2004,18(1):1-8
Pancreatic cancer has an extremely poor prognosis, due, in part, to lack of methods for early diagnosis. The present study was designed to evaluate the potential of labeling low‐density lipoprotein (LDL) with a radionuclide using a lipid chelating agent, bis(stearylamide) of diethylenetriaminepentaacetic acid (L), to detect pancreatic tumors by gamma‐scintigraphy. Previous studies indicated that the difficulty of visualization of pancreatic tumors was due to their poor vascularization. This study compares the ability of two radiotracers, 111In–L–LDL and 153Gd–L–LDL to target highly vascularized rat pancreatic tumors (AR4‐2J) implanted in nude mice. Biodistribution studies showed that the tumor uptake of 111In–L–LDL and 153Gd–L–LDL tracers was twofold and fivefold higher respectively than with the controls (111In citrate and 153Gd citrate respectively). These tracers would thus be suitable for scintigraphic imaging. We show here that LDL could be employed as a delivery system for tracers such as 111In or 153Gd when these two radionuclides are complexed by a lipid‐chelating anchor, and that 111In–L–LDL and 153Gd–L–LDL enabled better visualization of the pancreatic tumor tissues, with a better result with 153Gd–L–LDL. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
9.
Madalina Deaconu Nicolas Fournier Etienne Tanré 《Methodology and Computing in Applied Probability》2003,5(2):131-158
By continuing the probabilistic approach of Deaconu et al. (2001), we derive a stochastic particle approximation for the Smoluchowski coagulation equations. A convergence result for this model is obtained. Under quite stringent hypothesis we obtain a central limit theorem associated with our convergence. In spite of these restrictive technical assumptions, the rate of convergence result is interesting because it is the first obtained in this direction and seems to hold numerically under weaker hypothesis. This result answers a question closely connected to the Open Problem 16 formulated by Aldous (1999). 相似文献
10.