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91.
Monika Hassel Michael G. Cornelius Jochen vom Brocke Heinz H. Schmeiser 《Electrophoresis》2010,31(2):299-302
The model organism Hydra has been used for molecular studies for more than 20 years, however, its DNA base composition has not been determined yet. We have analyzed DNA and total RNA of the freshwater polyp Hydra magnipapillata with two independent procedures of high accuracy and sensitivity – fluorescence labeling of nucleotides followed by CE‐LIF detection and 32P‐postlabeling. DNA of Hydra was digested either to deoxyribonucleoside‐5′‐monophosphates or deoxyribonucleoside‐3′‐monophosphates selectively conjugated with the fluorescent dye 4,4‐difluoro‐5,7‐dimethyl‐4‐bora‐3a,4a‐diaza‐s‐indacene‐3‐propionyl ethylene diamine hydrochloride (BODIPY FL EDA) separated and detected using CE‐LIF. Both versions of the assay revealed a high A+T composition of 78 and 71%, whereas total DNA methylation (5‐methyldeoxycytidine) was 2.6 and 3.1%. Total Hydra RNA showed highest base levels for guanine (33%) and a level of 1.4% for pseudouracil. All values were in good agreement with those determined by the 32P‐postlabeling method. 相似文献
92.
93.
Dr. Joydev Hatai Dr. Christoph Hirschhäuser Prof. Dr. Carsten Schmuck Dr. Jochen Niemeyer 《ChemistryOpen》2020,9(7):786-792
A coumarin based probe for the efficient detection of hydrogen sulfide in aqueous medium is reported. The investigated coumarine-based derivative forms spherical nanoparticles in aqueous media. In presence of Pd2+, a metallosupramolecular coordination polymer is formed, which is accompanied by quenching of the coumarin emission at 390 nm. Its Pd2+ complex could be used as a probe for chemoselective detection of monohydrogensulfide (HS−). Presence of HS− leads to a'turn-on' fluorescence signal, resulting from decomplexation of Pd2+ from the metallosupramolecular probe. The probe was successfully applied for qualitative and quantitative detection of HS− in different sources of water directly collected from sea, river, tap and laboratory drain water, as well as in growth media for aquatic species. 相似文献
94.
95.
This work presents numerical simulations and selected results of the flow over aquatic canopies, consisting of artificial flexible rectangular blades, arranged in a well-defined order. The results obtained with three different Reynolds and Cauchy numbers are compared with experimental data achieving good agreement. The considered range of Cauchy numbers represents three different types of canopies ranging from rigid up to highly flexible plants. The transient flow data and blade positions are statistically analyzed to gain deeper understanding of the complex physical processes for this kind of fluid structure interaction. For example, the correlation of role of large scale motion of the flexible blades in conjunction with coherent vortex structures of the flow is addressed. (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
96.
One-bond Pt-Pt nuclear spin-spin coupling constants J(Pt-Pt) for closely related dinuclear Pt complexes can differ by an order of magnitude without any obvious correlation with Pt-Pt distances. As representative examples, the spin-spin couplings of the dinuclear Pt(I) complexes [Pt(2)(CO)(6)](2+) (1) and [Pt(2)(CO)(2)Cl(4)](2-) (2) have been computationally studied with a recently developed relativistic density functional method. The experimental values are (1)J((195)Pt-(195)Pt) = 5250 Hz for 2 but 551 Hz for 1. Many other examples are known in the literature. The experimental trends are well reproduced by the computations and can be explained based on the nature of the ligands that are coordinated to the Pt-Pt fragment. The difference for J(Pt-Pt) of an order of magnitude is caused by a sensitive interplay between the influence of different ligands on the Pt-Pt bond, and relativistic effects on metal-metal and metal-ligand bonds as well as on "atomic orbital contributions" to the nuclear spin-spin coupling constants. The results can be intuitively rationalized with the help of a simple qualitative molecular orbital diagram. 相似文献
97.
Upon irradiation, cyclic enol ethers such as 1-methoxy-cyclopentene (4) mainly add across the cyano group of benzonitrile (1), under formation of 2-azabutadienes of an imidoester type. This is in agreement with the so-called Δ G-correlation which was reported earlier (ref. 5 and 6). 4-Phenyloxazole (9) is formed from 1 and 1,3-dioxole (5) probably by a similar photochemical process followed by electrocyclic ring opening and hydrolysis. The low yield of the latter photoreaction and the almost exergonic electron transfer between 5 and 1 may point to back electron transfer as the main energy wasting process. From 1 and 2,3-dihydrido-furan (2) only the ortho cycloadduct 6 has been isolated in low yields. 相似文献
98.
Philipp M. Cromm Jochen Spiegel Dr. Tom N. Grossmann Prof. Dr. Herbert Waldmann 《Angewandte Chemie (International ed. in English)》2015,54(46):13516-13537
Small GTPases are a family of GDP‐/GTP‐binding proteins that serve as biomolecular switches inside cells to control a variety of essential cellular processes. Aberrant function and regulation of small GTPases is associated with a variety of human diseases, thus rendering these proteins highly interesting targets in drug discovery. However, this class of proteins has been considered “undruggable”, as intensive decade‐long efforts did not yield clinically relevant direct modulators of small GTPases. Recently, the targeting of small GTPases has gained fresh impetus through the discovery of novel transient cavities on the protein surfaces and the application of new targeting strategies. Besides Ras proteins, other small GTPases have attracted increased attention since improved biological insight in combination with novel targeting strategies identified them as promising targets in drug discovery. This Review gives an overview of relevant aspects of the superfamily of small GTPases and summarizes recent progress and perspectives for the direct modulation of these challenging targets. 相似文献
99.
Determination of heavy metal complexes with humic substances by HPLC/ICP-MS coupling using on-line isotope dilution technique 总被引:3,自引:0,他引:3
An isotope dilution mass spectrometric (IDMS) method has been developed for the simultaneous determination of the complexes
of 11 heavy metals (Ag, Cd, Cu, Mo, Ni, Pb, Tl, U, W, Zn and Zr) with humic substances (HS) by coupling HPLC with ICP-MS and
applying the on-line isotope dilution technique. The HPLC separation was carried out with size exclusion chromatography. This
HPLC/ICP-IDMS method was applied to samples from a brown water, ground water, sewage and seepage water as well as for a sample
containing isolated fulvic acids. The total contents of heavy metals and of their complexes were analyzed in these samples
with detection limits in the range of 5–110 ng/L. The analysis of heavy metal/HS complexes from the different waters resulted
in characteristic fingerprints of the distribution pattern of heavy metals in the separated HS fractions. A comparison between
the total heavy metal concentrations and their portions bound to humic substances showed distinct differences for the various
metals. Simultaneous 12C detection was used for the characterization of HS complexes not identified by UV detection and for the determination of
relative DOC concentrations of chromatographic peaks.
Received: 21 February 1997 / Revised: 27 May 1997 / Accepted: 28 May 1997 相似文献
100.