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91.
Alex Man-Hei Yip Justin Shum Dr. Hua-Wei Liu Huipeng Zhou Meiqi Jia Niu Niu Yongxin Li Prof. Cong Yu Prof. Kenneth Kam-Wing Lo 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(38):8970-8974
This communication reports novel luminescent rhenium(I)–polypyridine complexes appended with a perylene diimide (PDI) or benzoperylene monoimide (BPMI) moiety through a non-conjugated linker. The photophysical and photochemical properties originating from the interactions of the metal polypyridine and perylene units were exploited to afford new cellular reagents with thiol-sensing capability and excellent photocytotoxic activity. 相似文献
92.
93.
At increasing external load, numerous microcracks propagate in discrete and successive stages within a body of concrete material according to the hierarchy of their tensile fracture strengths. Each microcrack propagation is conditional upon the statistical encounter of its associated fracture criterion. This paper shows the development of a statistical model for the progressive microcrack growth process within a body of concrete material at monotonic uniaxial loading in compression to ultimate failure. This model is formulated by using the Weibull's statistical theory of the strength of materials. The body of heterogeneous concrete material is simulated as a continuum comprising a large population of microscopic “weakest-link” isoenergy elements, each of which contains a unit-volume of representative micro-structural material which is linearly elastic, homogeneous and isotropic. The statistical modelling is derived from the stochastic evaluation of the tensile micro-fracture probabilities of these isoenergy elements at increasing global uniaxial compressive strains. 相似文献
94.
Yuning Hong Hao Xiong Jacky Wing Yip Lam Dr. Matthias Häußler Dr. Jianzhao Liu Yong Yu Yongchun Zhong Dr. Herman H. Y. Sung Dr. Ian D. Williams Prof. Kam Sing Wong Prof. Ben Zhong Tang Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(4):1232-1245
Whereas most conventional DNA probes are flat disklike aromatic molecules, we explored the possibility of developing quadruplex sensors with nonplanar conformations, in particular, the propeller‐shaped tetraphenylethene (TPE) salts with aggregation‐induced emission (AIE) characteristics. 1,1,2,2‐Tetrakis[4‐(2‐triethylammonioethoxy)phenyl]ethene tetrabromide (TPE‐ 1 ) was found to show a specific affinity to a particular quadruplex structure formed by a human telomeric DNA strand in the presence of K+ ions, as indicated by the enhanced and bathochromically shifted emission of the AIE fluorogen. Steady‐state and time‐resolved spectral analyses revealed that the specific binding stems from a structural matching between the AIE fluorogen and the DNA strand in the folding process. Computational modeling suggests that the AIE molecule docks on the grooves of the quadruplex surface with the aid of electrostatic attraction. The binding preference of TPE‐ 1 enables it to serve as a bioprobe for direct monitoring of cation‐driven conformational transitions between the quadruplexes of various conformations, a job unachievable by the traditional G‐quadruplex biosensors. Methyl thiazolyl tetrazolium (MTT) assays reveal that TPE‐ 1 is cytocompatible, posing no toxicity to living cells. 相似文献
95.
A method was developed for high-throughput determinations of 7 elements in food samples, namely antimony (Sb), arsenic (As), cadmium (Cd), chromium (Cr), lead (Pb), mercury (Hg), and tin (Sn). The samples were digested by closed-vessel microwave-assisted digestion using concentrated nitric acid (HNO3) as the medium, followed by microwave- assisted evaporation to concentrate the sample solutions before dilution to the desired volume. The microwave-assisted evaporation procedure effectively reduced the final acid concentration to around 8% before analysis by inductively coupled plasma-mass spectrometry (ICP-MS). This reduction allows determination by ICP-MS to proceed without further sample dilution, which would affect the detection limit. The method was validated, and method recoveries for As, Cd, Cr, Pb, and Hg were within the certified ranges of the chosen certified reference materials. Recoveries of the 7 elements from spiked samples ranged from 93.1 to 103.6%. The standard uncertainties of precision for the 7 elements were between 3.1 and 4.3%. Interlaboratory comparison studies for As, Cd, and Pb gave z-scores ranging from -0.2 to 0.3. 相似文献
96.
Yip HL Zou J Ma H Tian Y Tucker NM Jen AK 《Journal of the American Chemical Society》2006,128(40):13042-13043
The one-dimensional (1-D) self-assembly property of an n-type hexaazatrinaphthylene (HATNA) discotic pi-conjugated molecule was studied. Structurally robust unimolecular columnar stacks of HATNA with tunable length have been fabricated through a combination of supramolecular self-assembly and post-polymerization approach. Moreover, microcontact printing can be utilized to transfer the self-assembled nanostructures to the surface to create desired functional patterns. 相似文献
97.
We have developed an efficient Pd(II)-catalyzed enantioselective oxidative tandem cyclization strategy using molecular oxygen as a green oxidant for the double 5-exo-trig cyclizations of N-(2-allylaryl) amides to afford a variety of indolines in good yields without the formation of undesired monocyclization products. By employing Pd(TFA)2/(-)-sparteine as the chiral catalyst, we obtained tandem cyclization products with high enantioselectivity (up to 91% ee). 相似文献
98.
ZuJin Zhao DanDan Liu Jacky Wing Yip Lam Ping Lu Bing Yang YuGuang Ma Ben Zhong Tang 《中国科学:化学(英文版)》2010,53(11):2311-2317
The theoretical calculation of the charge mobility of 2,5-bis(trialkylsilylethynyl)-1,1,3,4-tetraphenylsiloles is presented. B3LYP/6-31* calculations demonstrated that these silole molecules possessed large coupling matrix elements and reorganization energies for electron and hole transfers and high electron mobilities. The bulkiness of the trialkyl substituents influenced the charge mobility of the silole molecules, with the smaller trimethyl group imparting higher charge mobility than triethyl and triisopropyl substituents. 相似文献
99.
100.
Metallic Ag nanoparticles have been converted to Ag2Se nanoparticles at ambient temperature and open atmosphere by UV photodissociation of adsorbed CSe2 on the Ag core surface. The photolysis could be prevented at any stage yielding Ag@Ag2Se core-shell structures of different thickness. Depending on the initial Ag nanoparticle size, either hollow or filled nanocrystals of Ag2Se could be prepared. The Kirkendall effect has been proposed to account for the formation of hollow nanoparticles. A coated-sphere Drude model has been used to explain the redshift of the Ag plasmon band as a function of the Ag2Se shell thickness as well as to provide the first estimates of the wavelength-dependent dielectric function of Ag2Se. This photochemical method might be especially promising for carrying out a direct room-temperature phototransformation of metallic into semiconductor nanostructures already assembled on surface templates. 相似文献