全文获取类型
收费全文 | 135篇 |
免费 | 5篇 |
专业分类
化学 | 103篇 |
晶体学 | 4篇 |
力学 | 5篇 |
数学 | 19篇 |
物理学 | 9篇 |
出版年
2023年 | 3篇 |
2022年 | 8篇 |
2021年 | 1篇 |
2020年 | 3篇 |
2019年 | 3篇 |
2018年 | 5篇 |
2017年 | 4篇 |
2016年 | 14篇 |
2015年 | 6篇 |
2014年 | 5篇 |
2013年 | 18篇 |
2012年 | 10篇 |
2011年 | 17篇 |
2010年 | 3篇 |
2009年 | 5篇 |
2008年 | 4篇 |
2007年 | 1篇 |
2006年 | 1篇 |
2005年 | 2篇 |
2003年 | 1篇 |
2000年 | 1篇 |
1999年 | 1篇 |
1997年 | 2篇 |
1988年 | 1篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1980年 | 1篇 |
1973年 | 1篇 |
1966年 | 1篇 |
1959年 | 3篇 |
1958年 | 2篇 |
1957年 | 1篇 |
1946年 | 1篇 |
1945年 | 1篇 |
1913年 | 1篇 |
1910年 | 1篇 |
1909年 | 1篇 |
排序方式: 共有140条查询结果,搜索用时 15 毫秒
131.
132.
Glutamic acid can be titrated quantitatively against standard cadmium acetate using 4-(2-thiozolyl azo) resorcin as indicator in presence of boric acid-borax buffer at pH 9.0. Small concentrations of other natural amino acids do not interfere with the titration. However the presence of an equivalent molar concentration of histidine can cause an error of about 6%. 相似文献
133.
Manuel et al. (Discret. Appl. Math. 157(7):1486–1495, 2009) obtained the exact wirelength of an r-dimensional hypercube into a path as well as a 2?r/2?×2ér/2ù{2^{lfloor r/2rfloor}times 2^{lceil r/2rceil}} grid and conjectured the same for a folded hypercube. In this paper we solve the edge isoperimetric problem for folded hypercubes and thereby obtain the exact wirelength of folded hypercubes into paths. Further we compute the exact wirelength of the r-dimensional folded hypercubes into 2 k × 2 r−k grids. 相似文献
134.
Gunjan Chauhan Suvarcha Chauhan Surbhi Soni Anand Kumar Devendra Singh Negi Indra Bahadur 《中国化学会会志》2023,70(4):879-893
CoS@MorphcdtH NPs and CoS@4-MPipzcdtH NPs were synthesized by precipitation method involving three mechanisms: inclusion, occlusion, and adsorption. The synthesized NPs were characterized with the help of UV-Vis spectroscopy, FESEM-EDAX, powder x-ray diffraction, TEM, ESIMS, TG/DSC analysis. The morphology of the CoS@MorphcdtH NPs and CoS@4-MPipzcdtH NPs were hexagonal and rectangular, and the particles were in the range 7–12 nm. UV–visible spectral measurements showed surface plasmon resonance at 320 nm–340 nm with band gap of 3.65 eV–3.86 eV. The catalytically active CoSNPs called were investigated for the reduction of 4-nitrophenol (4-NP) via hydrogenation using sodium borohydride (NaBH4) as a reducing agent. Both the CoS NPs successfully reduced 4-NP to 4- aminophenol (4-AP) in a short time, catalytic performances are almost unchanged for the first five cycles. Herein, we report the preparation and characterizations of efficient active CoS NPs consisting carbodithioic acid framework as a support/capping material, along with catalytic property. 相似文献
135.
Smeazzetto S Schröder I Thiel G Moncelli MR 《Physical chemistry chemical physics : PCCP》2011,13(28):12935-12939
Phosholamban (PLN) is involved in the contractility of cardiac muscles by regulating the intracellular calcium concentration (Ca(2+)(cyt)) of cardiac myocytes. This occurs via a modulation of the sarco-/endoplasmic CaATPase (SERCA). In spite of high-resolution structures the molecular mode of PLN action is yet not known. In the present paper we readdress the question whether PLN proteins can generate ion channel activity. Reconstitution of PLN in planar lipid bilayers reveals single channel fluctuations, which are characterized by two conductance levels, long open/closed dwell times, moderate selectivity between monovalent cations and no perceivable Ca(2+) permeability. The PLN generated channel activity could be inhibited by a PLN antibody (abPLN) implying that the channel activity is indeed due to the inherent channel function of the PLN protein. 相似文献
136.
Theodore B. Trafalis Indra Adrianto Michael B. Richman S. Lakshmivarahan 《Computational Management Science》2014,11(4):403-418
Learning from imbalanced data, where the number of observations in one class is significantly larger than the ones in the other class, has gained considerable attention in the machine learning community. Assuming the difficulty in predicting each class is similar, most standard classifiers will tend to predict the majority class well. This study applies tornado data that are highly imbalanced, as they are rare events. The severe weather data used herein have thunderstorm circulations (mesocyclones) that produce tornadoes in approximately 6.7 % of the total number of observations. However, since tornadoes are high impact weather events, it is important to predict the minority class with high accuracy. In this study, we apply support vector machines (SVMs) and logistic regression with and without a midpoint threshold adjustment on the probabilistic outputs, random forest, and rotation forest for tornado prediction. Feature selection with SVM-recursive feature elimination was also performed to identify the most important features or variables for predicting tornadoes. The results showed that the threshold adjustment on SVMs provided better performance compared to other classifiers. 相似文献
137.
Xiuquan Zhou Brandon Wilfong Xinglong Chen Craig Laing Indra R. Pandey Ying-Pin Chen Yu-Sheng Chen Duck-Young Chung Mercouri G. Kanatzidis 《Angewandte Chemie (International ed. in English)》2023,62(14):e202301191
Synthesizing solids in molten fluxes enables the rapid diffusion of soluble species at temperatures lower than in solid-state reactions, leading to crystal formation of kinetically stable compounds. In this study, we demonstrate the effectiveness of mixed hydroxide and halide fluxes in synthesizing complex Sr/Ag/Se in mixed LiOH/LiCl. We have accessed a series of two-dimensional Sr(Ag1−xLix)2Se2 layered phases. With increased LiOH/LiCl ratio or reaction temperature, Li partially substituted Ag to form solid solutions of Sr(Ag1−xLix)2Se2 with x up to 0.45. In addition, a new type of intergrowth compound [Sr3Se2][(Ag1−xLix)2Se2] was synthesized upon further reaction of Sr(Ag1−xLix)2Se2 with SrSe. Both Sr(Ag1−xLix)2Se2 and [Sr3Se2][(Ag1−xLix)2Se2] exhibit a direct band gap, which increases with increasing Li substitution (x). Therefore, the band gap of Sr(Ag1−xLix)2Se2 can be precisely tuned via fine-tuning x that is controlled by only the flux ratio and temperature. 相似文献
138.
Paul Manuel Rajan Bharati Indra Rajasingh Chris Monica M 《Journal of Discrete Algorithms》2008,6(1):20-27
A minimum metric basis is a minimum set W of vertices of a graph G(V,E) such that for every pair of vertices u and v of G, there exists a vertex wW with the condition that the length of a shortest path from u to w is different from the length of a shortest path from v to w. The honeycomb and hexagonal networks are popular mesh-derived parallel architectures. Using the duality of these networks we determine minimum metric bases for hexagonal and honeycomb networks. 相似文献
139.
The structure activity relationship between the C??-C?? methylene double bond on the aglycone of steviol glycosides and the corresponding impact on their sweet taste has been reported here for the first time. It has been observed that converting stevioside and rebaudioside A to their corresponding ketones by switching the doubly bonded methylene on C-17 for a ketone group actually removes the sweet taste properties of these molecules completely. Regenerating the original molecules tends to restore the sweet taste of both the steviol glycosides. Thus this C??-C?? methylene double bond in rebaudioside A and stevioside can be regarded as a pharmacophore essential for the sweetness property of these molecules. 相似文献
140.