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31.
In this study, an improved process for the synthesis of etorphine and dihydroetorphine from codeine with an overall yield of 2.7% and 1.5% respectively is described. The structure of 19‐propylthevinol 7 was verfied by X‐ray structure analysis. This result is promising for synthesizing various morphine‐based drugs. 相似文献
32.
33.
Hugh Chaffey‐Millar Gene Hart‐Smith Christopher Barner‐Kowollik 《Journal of polymer science. Part A, Polymer chemistry》2008,46(5):1873-1892
A mass spectrometry analysis has been performed on complex architecture polymeric material produced during reversible addition fragmentation chain transfer (RAFT) polymerizations yielding star polymers. Para‐acetoxystyrene (AcOSty) has been polymerized at 60 °C, using azobisisobutyronitrile (AIBN) as the thermally decomposing initiator, in the presence of the R‐group approach tetrafunctional RAFT agent (1,2,4,5‐tetrakis‐(2‐phenyl‐thioacetyl‐sulfanylmethyl)‐benzene). In addition to ideal star material, a variety of products unique to this mode of polymerization have been identified. These include star–star couples, stars terminated with initiator fragments, star–star couples terminated with initiator fragments and linear polymers, supporting the notion that these species are responsible for the structured molecular‐weight distributions measured for these systems when analyzed via gel permeation chromatography. The analysis begins with a study of AcOSty polymerizing (i) in the absence of any mediating agent and (ii) in the presence of a monofunctional RAFT agent, revealing the mode of termination of propagating poly(AcOSty) radicals as combination and that some ionization biases exist among variants of poly (AcOSty). The interpretation of the mass spectrometry data has been aided by a novel kinetic model of star polymerizations, allowing the rationalization of experimental observations with theoretical expectations. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1873–1892, 2008 相似文献
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35.
Yu‐Pin Wang Hsien‐Li Leu Tso‐Shen Lin Yu Wang Gene‐Hsiang Lee 《Acta Crystallographica. Section C, Structural Chemistry》2009,65(3):m131-m134
In the structures of each of the title compounds, [CrBr(C6H5O2)(NO)2], (I), and [CrBr(C12H9O)(NO)2], (II), one of the nitrosyl groups is located at a site away from the exocyclic carbonyl C atom of the cyclopentadienyl (Cp) ring, with twist angles of 174.5 (3) and 172.5 (1)°. The observed orientation is surprising, since the NO group is expected to be situated trans to an electron‐rich C atom in the ring. The organic carbonyl plane is turned away from the Cp ring plane by 5.6 (8) and 15.2 (3)°in (I) and (II), respectively. The exocyclic C—C bond in (I) is bent out of the Cp ring plane towards the Cr atom by 2.8 (3)°, but is coplanar with the Cp ring in (II); the angle is 0.1 (1)°. 相似文献
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Xie R Johnson W Rodriguez L Gounder M Hall GS Buckley B 《Analytical and bioanalytical chemistry》2007,387(8):2815-2822
To study the carboplatin–protein interaction, a sensitive method using size exclusion chromatography coupled to inductively
coupled plasma mass spectrometry (SEC–ICP–MS) was developed. The complexes formed between plasma proteins and carboplatin
were monitored and identified with this method. Composite blood plasma samples from patients who were undergoing chemotherapy
were analyzed, and carboplatin was found to bind plasma proteins. In addition, blank plasma samples were spiked with carboplatin
and were analyzed as a time course study, and the results confirmed that carboplatin formed complexes with plasma proteins,
primarily albumin and γ-globulin. To further substantiate the study, these two proteins were incubated with carboplatin. The
binding between carboplatin and these proteins was then characterized qualitatively and quantitatively. In addition to a one-to-one
binding of Pt to protein, protein aggregation was observed. The kinetics of the binding process of carboplatin to albumin
and γ-globulin was also studied. The initial reaction rate constant of carboplatin binding to albumin was determined to be
0.74 M−1 min−1, while that for γ-globulin was 1.01 M−1 min−1, which are both lower than the rate constant of the cisplatin–albumin reaction previously reported. 相似文献
39.
[formula: see text] The allylboration of alkenes with allyldibromoborane is described. Utilizing an improved methodology for the synthesis of allyldibromoborane, 1,3-dienes, styrene, and even isolated alkenes could be carbometalated in high yield regio- and stereospecifically at 0 degree C. This high reactivity of allyldibromoborane significantly expands the scope of carbometalations of alkenes. 相似文献
40.
Frdric Tronc Warner Chen Mitchell A. Winnik Sarah T. Eckersley Gene D. Rose J. M. Weishuhn D. M. Meunier 《Journal of polymer science. Part A, Polymer chemistry》2002,40(22):4098-4116
This article describes the results of experiments examining the competition between the polymer diffusion rate and the crosslinking rate in low‐glass‐transition‐temperature, epoxy‐containing latex films in the presence of a diamine. We examined films formed from donor‐ and acceptor‐labeled poly(butyl acrylate‐co‐methyl methacrylate‐co‐glycidyl methacrylate) copolymer latex and studied the influence of several parameters on the growth rate of gel content and the rate of polymer diffusion. These factors include the molecular weight of the latex polymer, the presence or absence of a diamine crosslinking agent, and the cure protocol. The results were compared to the predictions of a recent theory of the competition between crosslinking and polymer diffusion across interfaces. In the initially formed films, polymer diffusion occurs more rapidly than the chemical reaction rate. Therefore, these films fall into the fast‐diffusion category of this model. In our system (unlike in the model), the latex polymer has a broad distribution of molecular weights and a distribution of diffusivities. The shortest chains contribute to the early time diffusion that we measure. At later stages of our experiment, slower diffusing species contribute to the signal that we measure. The diffusion time decreases substantially, and we observe a crossover to a regime in which the chemical reaction dominates. The increases in chain branching and gel formation bring polymer diffusion to a halt. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 4098–4116, 2002 相似文献