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961.
Michael H. Huang Hermes M. Soyez Bruce S. Dunn Jeffrey I. Zink Allan Sellinger C. Jeffrey Brinker 《Journal of Sol-Gel Science and Technology》2008,47(3):300-310
Surfactant-templated mesostructured sol–gel films formed by evaporation induced self assembly (EISA) exhibit highly-ordered
hexagonal, lamellar, and cubic structures. The steady-state dip-coating configuration allows both the chemistry and the dynamics
of the EISA process to be traced in real time because the steps involved in the formation of the mesostructured material are
separated both spatially and temporally in the dip-coating direction. The dynamic processes occurring during film formation
can be conveniently monitored by the combination of interferometry and fluorescence spectroscopy of incorporated molecular
probes. The selected probes respond to changes in their rotational mobility and the surrounding solvent composition and report
these changes through their fluorescence characteristics. By taking in situ fluorescence spectra at various positions within
the progressively thinning film, changes in the solvent composition, onset of micelle formation and further organization to
the final mesophase structure can be followed. The luminescence of the probe molecule is measured with a spatial resolution
of 100 μm. Two categories of surfactant-templated mesostructured sol–gel films were examined. Cetyltrimethylammonium bromide
(CTAB) systems assemble into a 2-D hexagonal surfactant/silica mesophase with the surfactant concentration used in this study.
CTAB dodecylmethacrylate systems assemble into a lamellar mesophase, which can be further polymerized to form a poly(dodecylmethacrylate)/silica
hybrid nanocomposite that mimics nacre. X-ray diffraction patterns, transmission electron microscopy images, and other techniques
are used to characterize the final films. 相似文献
962.
Mainak Majumder Karin Keis Xin Zhan Corey Meadows Jeggan Cole Bruce J. Hinds 《Journal of membrane science》2008,316(1-2):89-96
A membrane structure consisting of an aligned array of open ended carbon nanotubes (7 nm i.d.) spanning across an inert polymer matrix allows the diffusive transport of aqueous ionic species through CNT cores. The plasma oxidation process that opens CNTs tips inherently introduces carboxylic acid groups at the CNT tips, which allows for a limited amount of chemical functional at the CNT pore entrance. However for numerous applications, it is important to increase the density of carboxylic acid groups at the pore entrance for effective separation processes. Aqueous diazonium-based electrochemistry significantly increases the functional density of carboxylic acid groups. pH dependent dye adsorption–desorption and interfacial capacitance measurements indicate 5–6 times increase in functional density. To further control the spatial location of the functional chemistry, a fast flowing inert liquid column inside the CNT core is found to restrict the diazonium grafting to the CNT tips only. This is confirmed by the increased flux of positively charged with anionic functionality. The electrostatic enhancement of ion diffusion is readily screened in 0.1 M electrolyte solution consistent with the membrane pore geometry and increased functional density. 相似文献
963.
Bruce MI Cole ML Fung RS Forsyth CM Hilder M Junk PC Konstas K 《Dalton transactions (Cambridge, England : 2003)》2008,(31):4118-4128
The ambient temperature reaction of the N-heterocyclic carbenes (NHCs) 1,3-dimesitylimidazol-2-ylidene (IMes) and 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene (IDipp) with the triruthenium cluster [Ru(3)(CO)(12)], in a 3 : 1 stoichiometric ratio, results in homolytic cleavage of the cluster to quantitatively afford the complexes [Ru(CO)(4)(NHC)] (; NHC = IMes, ; NHC = IDipp). Reaction of the 2-thione or hydrochloride precursors to IMes, i.e. S[double bond, length as m-dash]IMes and IMes.HCl, with the same triruthenium cluster affords the complexes [Ru(4)(mu(4)-S)(2)(CO)(9)(IMes)(2)] () and [Ru(4)(mu(4)-S)(CO)(10)(IMes)(2)] () (3 : 1 and 2 : 1 reaction), and [{Ru(mu-Cl)(CO)(2)(IMes)}(2)] () (3 : 1 reaction) respectively. By contrast, the complex [Ru(3)(mu(3)-S)(2)(CO)(7)(IMeMe)(2)] (), where IMeMe is 1,3,4,5-tetramethylimidazol-2-ylidene, is the sole product of the 2 : 1 stoichiometric reaction of S[double bond, length as m-dash]IMeMe with [Ru(3)(CO)(12)]. Compounds -, and have been structurally characterised by single crystal X-ray diffraction. 相似文献
964.
We describe the development of a new palladium-catalyzed method to generate ketones via the oxidative coupling of two arenes and CO. This transformation is catalyzed by simple palladium salts, and is postulated to proceed via the conversion of arenes into high energy aroyl triflate electrophiles. Exploiting the latter can also allow the synthesis of unsymmetrical ketones from two different arenes.A palladium catalyzed route to prepare aryl ketones from their two fundamental building blocks, two arenes and carbon monoxide, is described. 相似文献
965.
Bruce E. Bursten Shentan Chen Malcolm H. Chisholm 《Journal of organometallic chemistry》2008,693(8-9):1547-1551
The density functional theory (DFT) calculations were used to study the effects of PCP ancillary ligands on the relative stabilities of hydrido amido complexes and ammonia coordination complexes. Calculations on the four compounds 1a, 1b, 2a and 2b containing PCP ligands with t-butyl groups on P atoms showed that 1b is more stable than 1a and 2a is more stable than 2b. Calculations also showed that the relative energies of hydrido amido complexes with respect to the isomeric ammonia coordinated complexes vary with the different substituent groups (R = H, Me and tBu) on the P atoms of the PCP ligands. An alternative method to study the ligand effects introduced by different substituents on the P atoms is to vary the nuclear charge on the P atoms of PCP ligand. The relative energies were predicted to decrease with the nuclear charge of the P atoms on the PCP ligands, which indicates that increasing the electron donating ability tend to favor the hydrido amido complexes over the ammonia coordination complexes: 相似文献
966.
Jocelyn C. Bruce Klaus R. Koch 《Acta Crystallographica. Section C, Structural Chemistry》2008,64(1):m1-m4
The crystal and molecular structures of N‐benzoyl‐N′,N′‐dibutylselenourea (HL), C16H24N2OSe, and the corresponding complex bis(N‐benzoyl‐N′,N′‐dibutylselenoureato‐κ2Se,O)palladium(II), [Pd(C16H23N2OSe)2], are reported. The selenourea molecule is characterized by intermolecular hydrogen bonds between the selenoamidic H atom and the Se atom of a neighbouring molecule forming a dimer, presumably as a consequence of resonance‐assisted hydrogen bonding or π‐bonding co‐operativity. A second dimeric hydrogen bond is also described. In the palladium complex, the typical square‐planar coordination characteristic of such ligands results in a cis‐[Pd(L‐Se,O)2] complex. 相似文献
967.
968.
The Future of (Radio)-Labeled Compounds in Research and Development within the Life Science Industry
Dr. Volker Derdau Dr. Charles S. Elmore Dr. Thomas Hartung Dr. Bruce McKillican Dr. Tom Mejuch Claudia Rosenbaum Prof. Dr. Christine Wiebe 《Angewandte Chemie (International ed. in English)》2023,62(52):e202306019
In this review the applications of isotopically labeled compounds are discussed and put into the context of their future impact in the life sciences. Especially discussing their use in the pharma and crop science industries to follow their fate in the environment, in vivo or in complex matrices to understand the potential harm of new chemical structures and to increase the safety of human society. 相似文献
969.
Nicole Fernandez-Tejero Quentin Gauthier Sohee Cho Bruce R. McCord 《Electrophoresis》2023,44(3-4):371-377
The determination of tissue type is important when reconstructing a crime scene as skin cells may indicate innocent contact, whereas other types of cells, such as blood and semen, may indicate foul play. Up to now, there has been no specific DNA methylation-based marker to distinguish skin cell DNA from other body fluids. The goal of this study is to develop a DNA methylation-based assay to detect and identify skin cells collected at forensic crime scenes for use in DNA typing. For this reason, we have utilized a DNA methylation chip array-based genome-wide association study to identify skin-specific DNA methylation markers. DNA obtained from skin along with other body fluids, such as semen, saliva, blood, and vaginal epithelia, were tested using five genes that were identified as sites for potential new epigenetic skin markers. Samples were collected, bisulfite converted, and subjected to real-time polymerase chain reaction (PCR) with high-resolution melt analysis. In our studies, when using WDR11, PON2, and NHSL1 assays with bisulfite-modified PCR, skin/sweat amplicons melted at lower temperatures compared to blood, saliva, semen, and vaginal epithelia. One-way analysis of variance demonstrates that these three skin/sweat markers are significantly different when compared with other body fluids (p < 0.05). These results demonstrate that high-resolution melt analysis is a promising technology to detect and identify skin/sweat DNA from other body fluids. 相似文献
970.