全文获取类型
收费全文 | 671篇 |
免费 | 30篇 |
国内免费 | 6篇 |
专业分类
化学 | 429篇 |
晶体学 | 1篇 |
力学 | 22篇 |
数学 | 73篇 |
物理学 | 182篇 |
出版年
2023年 | 8篇 |
2022年 | 42篇 |
2021年 | 31篇 |
2020年 | 33篇 |
2019年 | 41篇 |
2018年 | 19篇 |
2017年 | 17篇 |
2016年 | 33篇 |
2015年 | 23篇 |
2014年 | 29篇 |
2013年 | 51篇 |
2012年 | 40篇 |
2011年 | 37篇 |
2010年 | 25篇 |
2009年 | 24篇 |
2008年 | 36篇 |
2007年 | 29篇 |
2006年 | 23篇 |
2005年 | 15篇 |
2004年 | 12篇 |
2003年 | 10篇 |
2002年 | 10篇 |
2001年 | 9篇 |
2000年 | 4篇 |
1997年 | 4篇 |
1996年 | 2篇 |
1995年 | 4篇 |
1994年 | 6篇 |
1993年 | 2篇 |
1992年 | 5篇 |
1991年 | 5篇 |
1990年 | 3篇 |
1989年 | 2篇 |
1988年 | 4篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1985年 | 5篇 |
1984年 | 6篇 |
1983年 | 5篇 |
1982年 | 7篇 |
1981年 | 2篇 |
1980年 | 6篇 |
1978年 | 4篇 |
1977年 | 3篇 |
1975年 | 4篇 |
1973年 | 3篇 |
1970年 | 3篇 |
1969年 | 3篇 |
1968年 | 3篇 |
1967年 | 2篇 |
排序方式: 共有707条查询结果,搜索用时 406 毫秒
31.
32.
Mohsin Ahmad Bhat Aijaz Ahmad Dar Adil Amin 《Journal of Dispersion Science and Technology》2013,34(4):514-520
Micellization parameters, critical micelle concentration (cmc), degree of counterion dissociation (α), aggregation number (n), critical packing parameter, and hydrophobic core volume of Dodecylpyridinium chloride (DPC) micelles were determined in presence of varying concentrations of sodium chloride (NaCl), sodium acetate (SAc), sodium propionate (SPr), ethylammonium chloride (EACl), diethylammonium chloride (DEACl), tetraethylammonium chloride (TEACl), and propylammonium chloride (PACl) through conductometric investigations at 298.15 K. The resulting data suggests that both counter and coions affect the cmc values‐cmc depressing tendency of the salts varies in order PACl≈NaCl>EACl>DEACl>TEACl>SPr>SAc, while the degree of counterion dissociation is dependent on the nature and concentration range of the added salt. Increasing salt concentration increases the relative hydrophobic volume of the micelles and coion has not much effect on aggregation number. 相似文献
33.
Ankit S. Macwan Nidhi Srivastava Saleem Javed Ashwani Kumar 《Applied biochemistry and biotechnology》2013,169(4):1397-1404
Enzyme “hexachlorocyclohexane (HCH) dehydrochlorinase LinA” mediates first step of aerobic microbial degradation of a chlorinated insecticide γ-HCH. The archetypal LinA-type1 consists of 156 amino acids that include a directly repeated hexapeptide motif GIHFAP at positions 141–146 and 148–153. Analysis of a series of LinA mutants, containing none, one, two, or three units of this repeated motif revealed that two units, as present in wild-type LinA, are required for its optimal activity and stability. Moreover, the presence of a bend in its secondary structure due to a proline residue that precedes the distal repeated unit contributes to enhanced LinA activity. 相似文献
34.
35.
The 4-(o-propargyloxy)styrylcoumarins are prepared by the condensation of O-propargylated salicylaldehyde with substituted coumarin-4-acetic acids. The intramolecular Diels–Alder reaction of 4-(o-propargyloxy)styrylcoumarins, without any catalyst gives fused-ring coumarins. The reaction in boiling nitrobenzene leads to aromatization of the initial Diels–Alder adduct and these aromatized products are highly fluorescent. 相似文献
36.
Adil Mustafa Elisa Pedone Lucia Marucci Despina Moschou Mirella Di Lorenzo 《Electrophoresis》2022,43(3):501-508
Effective methods for rapid sorting of cells according to their viability are critical in T cells based therapies to prevent any risk to patients. In this context, we present a novel microfluidic device that continuously separates viable and non-viable T-cells according to their dielectric properties. A dielectrophoresis (DEP) force is generated by an array of castellated microelectrodes embedded into a microfluidic channel with a single inlet and two outlets; cells subjected to positive DEP forces are drawn toward the electrodes array and leave from the top outlet, those subjected to negative DEP forces are repelled away from the electrodes and leave from the bottom outlet. Computational fluid dynamics is used to predict the device separation efficacy, according to the applied alternative current (AC) frequency, at which the cells move from/to a negative/positive DEP region and the ionic strength of the suspension medium. The model is used to support the design of the operational conditions, confirming a separation efficiency, in terms of purity, of 96% under an applied AC frequency of 1.5 × 106 Hz and a flow rate of 20 μl/h. This work represents the first example of effective continuous sorting of viable and non-viable human T-cells in a single-inlet microfluidic chip, paving the way for lab-on-a-chip applications at the point of need. 相似文献
37.
We describe a proposal for the generation of a single-mode photonic number state, |N〉, in a traveling wave optical field. The state is obtained by state reduction from an input coherent state using Kerr media. Our method is based on a previous scheme used for hole burning in the Fock space by minimizing the Mandel Q parameter. The same method was used by Maia et al., but ours is different, it requires only one single photon injected in the entire setup and one photon detection at the end. 相似文献
38.
A posteriori error analysis for nonconforming approximations of an anisotropic elliptic problem
下载免费PDF全文
![点击此处可从《Numerical Methods for Partial Differential Equations》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Boujemâa Achchab Abdellatif Agouzal Adil Majdoubi Driss Meskine Ali Souissi 《Numerical Methods for Partial Differential Equations》2015,31(3):950-976
We develop in this article an a posteriori error estimator for the P1‐nonconforming finite element approximation, for a diffusion‐reaction equation. We adopt the error in a constitutive law approach in two and three dimensional space, for not necessary piecewise constant data of problems. The efficiency and the reliability of our estimators are proved, neither Helmholtz decomposition of the error nor saturation assumption. The constants are explicitly given, which prove the robustness of these estimators. © 2014 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 31: 950–976, 2015 相似文献
39.
This paper presents the oil uptake of porous sorbent polymer sheets consisting of ultra‐high molecular weight polyethylene. A comprehensive set of experiments are performed showing the saturation contact time, retention value, mechanical properties, oil pick‐up ratio, pick‐up density, and dynamic dripping profile. Kinetic modeling of the oil sorption is also provided. The experimental results show a good correlation with the pseudo‐second order model. The sheets exhibit high oil uptake speeds, requiring less than 2 min in contact with the oil to reach saturation. The sheets fulfill the criteria of high uptake kinetics, high sorption capacity, and high mechanical strength simultaneously. Those characteristics enable their use in practical spill response. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
40.
Gizem Ertürk Nilay Bereli Pramod W. Ramteke Adil Denizli 《Applied biochemistry and biotechnology》2014,173(5):1250-1262
Myoglobin is a primary iron, and oxygen-binding protein of muscle tissues and levels can be an important diagnostic biomarker for acute myocardial infarction, myocardial necrosis, or other cardiac diseases. The establishment of myoglobin recognition systems is important because of its protein’s structural and functional values in physiology, biochemistry, and diagnostic value in some damaged muscle tissue and cardiac diseases. For this purpose, we used molecular imprinting technique for myoglobin recognition from aqueous solutions and human plasma. In the first step, myoglobin-imprinted poly(hydroxyethyl methacrylate) (PHEMA) cryogels (MGb-MIP) were prepared, and optimum myoglobin adsorption conditions were determined. Selectivity experiments have been done with the competitive proteins, and myoglobin adsorption from IgG and albumin-free human plasma was studied. The purity of the desorbed samples was determined with SDS-PAGE. The desorption efficiency and reusability of the MGb-MIP cryogels were tested, and it was shown that without any significant loss in the adsorption capacity, MGb-MIP cryogels can be used a number of times for myoglobin recognition and separation. 相似文献