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101.
One‐Pot Consecutive Catalysis by Integrating Organometallic Catalysis with Organocatalysis 下载免费PDF全文
The present study integrates two types of catalysis, namely, organometallic catalysis and organocatalysis in one reaction pot. In this process, the product of the first catalytic cycle acts as catalytic component for next catalytic cycle. The abnormal N‐heterocyclic carbene–copper‐based organometallic catalyst acts as an efficient catalyst for a click reaction to provide triazole, which, in turn, acts as an efficient organocatalyst for different organic transformations, for example, aza‐Michael addition and multicomponent reactions, in a consecutive fashion in the same reaction pot. 相似文献
102.
A simple epoxy-based oligomer 1 containing naphthylazobenzene-appended dithia-aza moieties was prepared. In UV–vis measurements, the proposed oligomer showed the ion-sensing ability to Hg2+ and Cu2+ ions. The discrimination between two differently responding Hg2+ and Cu2+ ions was also realised from ‘ON–OFF’ type fluorescence responses of 1. 相似文献
103.
Here, we present a novel and simple process of spheroid formation and in situ encapsulation of the formed spheroid without intervention. A hemispherical polydimethylsiloxane (PDMS) micromold was employed for the formation of uniform sized spheroids and two types of nano-porous membrane were used for the control of the crosslinking agent. We characterized the transport properties of the membrane, and the selection of alginate hydrogel as a function of gelation time, alginate concentration, and membrane type. Using the developed process and micromold, HepG2 cell spheroids were successfully formed and encapsulated in alginate without replating. This method allows spheroid encapsulation with minimal damage to the spheroid while maintaining high cell viability. We demonstrate the feasibility of this method in developing a bio-artificial liver (BAL) chip by evaluating viability and function of encapsulated HepG2 spheroids. This method may be applied to the encapsulation of several aggregating cell types, such as β-cells for islet formation and stem cells for embryonic body preservation, or as a model for tumor cell growth and proliferation in a 3D hydrogel environment. 相似文献
104.
A rapid and high-throughput isotope dilution LC-MS/MS method with online sample pre-concentration and clean-up using anionic mixed-mode SPE was described for the determination of closantel and rafoxanide in edible bovine and ovine tissues. Tissue samples were extracted with acetonitrile and acetone mixture (60:40, v/v). Sample pre-concentration, clean-up and analysis were completed simultaneously with the online MAX SPE LC-MS/MS system. Closantel-(13) C(6) and rafoxanide-(13) C(6) were used as the internal standards to improve the precision of the method. The method was validated with edible ovine and bovine tissues (muscle, kidney and liver) fortified at three different levels. The accuracy and RSD were 86-106% and ≤14%, respectively. This high-throughput method was suitable for routine quantitative analysis of closantel and rafoxanide in food safety surveillance samples. 相似文献
105.
Nguyen SD Yeon J Kim SH Halasyamani PS 《Journal of the American Chemical Society》2011,133(32):12422-12425
A new noncentrosymmetric (NCS) and polar material containing two lone-pair cations, Bi(3+) and I(5+), and exhibiting an Aurivillius-type (Bi(2)O(2))(2+) layer has been synthesized and structurally characterized. The material, BiO(IO(3)), exhibits strong second-harmonic generation (SHG), ~12.5 × KDP (or ~500 × α-SiO(2)), using 1064 nm radiation, and is found in the NCS polar orthorhombic space group Pca2(1) (No. 29). The structure consists of (Bi(2)O(2))(2+) cationic layers that are connected to (IO(3))(-) anions. The macroscopic polarity, observed along the c-axis direction, may be attributed to the alignment of the IO(3) polyhedra. In addition to the crystal structure and SHG measurements, polarization and piezoelectric measurements were performed, as well as electronic structure analysis. 相似文献
106.
Mercedes Fernandez Sau Daniela Rodriguez 《Advances in Data Analysis and Classification》2018,12(3):587-603
In this paper, we propose estimators based on the minimum distance for the unknown parameters of a parametric density on the unit sphere. We show that these estimators are consistent and asymptotically normally distributed. Also, we apply our proposal to develop a method that allows us to detect potential atypical values. The behavior under small samples of the proposed estimators is studied using Monte Carlo simulations. Two applications of our procedure are illustrated with real data sets. 相似文献
107.
We have imaged boron nitride nanotubes with atomic scale resolution using scanning tunneling microscopy. While some nanotubes show the expected triangular lattice pattern, the majority of the nanotubes show unusual stripe patterns which break the underlying symmetry of the boron nitride lattice. We identify the origin of the symmetry breaking and demonstrate that conventional STM imaging analysis is inadequate for boron nitride nanotubes. 相似文献
108.
Paul Chatelain Abhijit Sau Christopher N. Rowley Joseph Moran 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(42):15101-15105
Ideal organic syntheses involve the rapid construction of C?C bonds, with minimal use of functional group interconversions. The Suzuki–Miyaura cross‐coupling (SMC) is a powerful way to form biaryl linkages, but the relatively similar reactivity of electrophilic partners makes iterative syntheses involving more than two sequential coupling events difficult to achieve without additional manipulations. Here we introduce (hetero)aryl sulfones as electrophilic coupling partners for the SMC reaction, which display an intermediate reactivity between those of typical aryl (pseudo)halides and nitroarenes. The new complementary reactivity allows for rapid sequential cross‐coupling of arenes bearing chloride, sulfone and nitro leaving groups, affording non‐symmetric ter‐ and quateraryls in only 2 or 3 steps, respectively. The SMC reactivity of (hetero)aryl sulfones is demonstrated in over 30 examples. Mechanistic experiments and DFT calculations are consistent with oxidative addition into the sulfone C?S bond as the turnover‐limiting step. The further development of electrophilic cross‐coupling partners with complementary reactivity may open new possibilities for divergent iterative synthesis starting from small pools of polyfunctionalized arenes. 相似文献
109.
Pal I Basuli F Mak TC Bhattacharya S 《Angewandte Chemie (International ed. in English)》2001,40(15):2923-2925
110.
Semanti Basu Rama Acharyya William S. Sheldrick Heike Mayer-Figge Samaresh Bhattacharya 《Structural chemistry》2007,18(2):209-215
Reaction of thiosemicarbazones of salicylaldehyde and 2-hydroxyacetophenone (H2L1 and H2L2) with [Ir(PPh3)3Cl] affords complexes of type [Ir(PPh3)2(L)(H)] (L = L1 or L2) in ethanol. A similar reaction carried out in toluene affords the [Ir(PPh3)2(L)(H)] complexes along with complexes of type [Ir(PPh3)2(L)Cl], where a chloride is coordinated to iridium instead of the hydride. The structure of the [Ir(PPh3)2(L2)(H)] and [Ir(PPh3)2(L2)Cl] complexes has been determined by X-ray crystallography. Crystal data for [Ir(PPh3)2(L2)(H)]: space group, P21/c; crystal system, monoclinic; a=12.110(2) Å, b=17.983(4) Å, c=18.437(4) Å, β=103.42(3)°, Z=4; R 1=0.0591, wR 2=0.1107. Crystal data for [Ir(PPh3)2(L2)Cl]: space group, P21/c; crystal system, monoclinic; a=17.9374(11) Å, b=19.2570(10) Å, c=24.9135(16) Å, β=108.145(5)°, Z=4; R 1=0.0463, wR 2=0.0901. In all the complexes the thiosemicarbazones are coordinated to the metal center as dianionic tridentate O, N, S-donors and the two triphenylphosphines are trans. The complexes are diamagnetic (low-spin d? 6, S=0) and show intense MLCT transitions in the visible region. Cyclic voltammetry on all the [Ir(PPh3)2(L)(H)] and [Ir(PPh3)2(L)Cl] complexes shows a quasi-reversible Ir(III)–Ir(IV) oxidation within 0.55–0.78 V vs. SCE followed by an irreversible oxidation of the thiosemicarbazone within 0.91–1.27 V vs. SCE. An irreversible reduction of the thiosemicarbazone is also observed within ?1.10 to ?1.23 V vs. SCE. 相似文献