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91.
Functional MRI using intravascular contrast agents: detrending of the relative cerebrovascular (rCBV) time course 总被引:3,自引:0,他引:3
In pharmacological fMRI experiments in animal models, blood pool contrast agents may be used to map cerebral blood volume change as a surrogate for neural activation. When the background signal drift due to contrast agent washout is non-negligible over the duration of the signal changes of interest, time-course detrending is essential for accurate interpretation of the experiment. Detrending approaches based on estimation of the background signal from a baseline period of the time course prior to pharmacological (or functional) challenge were evaluated with the aim of identifying a robust method of estimating the contrast agent washout contribution to the background signal drift. For fMRI studies in the rat, it was found that a constrained fit of a mono-exponential washout model was more accurate than a constant background approximation and unconstrained fits for experiments investigating the functional response to rapid pharmacological challenges such as cocaine and amphetamine. Moreover, the constrained fitting approach allows shorter baseline periods than unconstrained extrapolation, reducing the required duration of the experiment. 相似文献
92.
Masciocchi N Ardizzoia GA Brenna S Castelli F Galli S Maspero A Sironi A 《Chemical communications (Cambridge, England)》2003,(16):2018-2019
Two new 3D homoleptic binary imidazolates, Cd(im)2 and Hg(im)2 (Him = imidazole), as well as [Hg(im)]NO3, containing 1D polycations of [Hg(im)]n(n+) formulation, have been prepared and characterized by ab-initio XRPD methods. 相似文献
93.
94.
The photochemistry of 4-haloanilines and 4-halo-N,N-dimethylanilines has been studied in apolar, polar aprotic, and protic solvents. Photophysical and flash photolysis experiments show that the reaction proceeds in any case from the triplet state. It is rather unreactive in apolar media, the highest value being Phi = 0.05 for the iodoanilines in cyclohexane. Changing the solvent has little effect for iodoanilines and for the poorly reacting bromo analogue, while it leads to a variation of over 2 orders of magnitude in the quantum yield for the chloro and fluoro derivatives. The triplets have been characterized at the UB3LYP/6-31G(d) level of theory, evidencing a deformation and an elongation (except for C-F) of the C-X bond. Homolytic fragmentation is in every case endothermic, but calculations in acetonitrile solution show that heterolytic cleavage of C-Cl and C-Br is exothermic. Experimentally, the occurrence of heterolytic fragmentation has been monitored through selective trapping of the resulting phenyl cation by allyltrimethylsilane. Heterolytic dechlorination occurs efficiently in polar media (e.g., Phi = 0.77 in MeCN), while debromination remains ineffective due to the short lifetime of the triplet. Heterolytic defluorination is efficient only in protic solvents (Phi = 0.48 in MeOH), in accord with calculations showing that in the presence of an ancillary molecule of water fragmentation is exothermic due to the formation of the strong H-F bond. The energy profile for both homo- and heterolytic dissociation paths has been mapped along the reaction coordinates in the gas phase and in acetonitrile. The conditions determining the efficiency and mode of dehalogenation have been defined. This is significant for devising synthetic methods via photogenerated phenyl cations and for rationalizing the photodegradation of halogenated aromatic pollutants and the phototoxic effect of some fluorinated drugs. 相似文献
95.
The authors prove that a proper monomial holomorphic mapping from the two-ball to the N-ball has degree at most 2N-3, and
that this result is sharp. The authors first show that certain group-invariant polynomials (related to Lucas polynomials)
achieve the bound. To establish the bound the authors introduce a graph-theoretic approach that requires determining the number
of sinks in a directed graph associated with the quotient polynomial. The proof also relies on a result of the first author
that expresses all proper polynomial holomorphic mappings between balls in terms of tensor products. 相似文献
96.
Bacchi Alessia Pelizzi Giancarlo Minardi Giovannina Pistuddi Angelo M. Solinas Costantino Chelucci Giorgio 《Transition Metal Chemistry》2002,27(3):274-278
Metal complexes of general formula M(L)X2 and M(L)X3 [L = (4S,5S)-2,2-dimethyl-4,5-bis{6-[(4,5-dihydro-4-(S)-(1-methylethyl)oxazol-2-yl)pyridin-2-yl]}-1,3-dioxolane] were obtained by reacting, respectively, CoII, CuII, NiII, and ZnII nitrate salts and the RhIII chloride salt, with a chiral C2-symmetric bis(oxazolinylpyridinyl)dioxolane (L) ligand, in MeOH/CHCl3 solution. A single crystal X-ray analysis was carried out on [Ni(L)(OH2)2](NO3)2 · 2H2O and the molecular structure of L was also determined. In the free ligand the two symmetric arms are essentially planar and oriented nearly perpendicular to the dioxolane average plane. In the Ni complex one seven-membered and two five-membered chelation rings are formed. The metal atom also lies on the C2 axis, and two symmetry-related water molecules complete the octahedral coordination environment. Both compounds crystallize in chiral space groups; the ligand crystallizes in orthorhombic system, space group C 2 2 21, Z = 4; the nickel complex crystallizes in tetragonal system, space group P 43 21 2, Z = 4. 相似文献
97.
Salvatore Sotgia Ciriaco Carru Bastianina Scanu Elisabetta Pisanu Manuela Sanna Gerard Aime Pinna Leonardo Gaspa Luca Deiana Angelo Zinellu 《Analytical and bioanalytical chemistry》2009,395(8):2577-2582
A rapid and simple short-end injection capillary zone electrophoresis method was developed for the quantification of plasma
uric acid. The separation was performed in an uncoated fused-silica capillary (50 μm ID, 60 cm total length, 10.2 cm effective
length) by using as a background electrolyte a 75 mmol/L glycylglycine solution titrated with NaOH 5 mol/L to pH 9.0, a voltage
of 28 kV, a cartridge temperature of 15 °C, and direct UV detection at 292 nm. Under optimized conditions, uric acid was determinate
in little more than 1 min (1.076 minutes). In order to verify the accuracy of the analysis, urate levels were measured in
543 apparently healthy volunteers by the new assay and our previous method, and the obtained data were compared by Passing–Bablock
regression, Bland–Altman test, and a new regression-based approach, which showed a good agreement between two methods. 相似文献
98.
Multitarget Drug Discovery for Alzheimer's Disease: Triazinones as BACE‐1 and GSK‐3β Inhibitors 下载免费PDF全文
Federica Prati Dr. Angela De Simone Dr. Paola Bisignano Dr. Andrea Armirotti Dr. Maria Summa Dr. Daniela Pizzirani Dr. Rita Scarpelli Dr. Daniel I. Perez Prof. Dr. Vincenza Andrisano Dr. Ana Perez‐Castillo Prof. Dr. Barbara Monti Francesca Massenzio Dr. Letizia Polito Prof. Dr. Marco Racchi Dr. Angelo D. Favia Dr. Giovanni Bottegoni Prof. Dr. Ana Martinez Prof. Dr. Maria Laura Bolognesi Prof. Dr. Andrea Cavalli 《Angewandte Chemie (International ed. in English)》2015,54(5):1578-1582
Cumulative evidence strongly supports that the amyloid and tau hypotheses are not mutually exclusive, but concomitantly contribute to neurodegeneration in Alzheimer′s disease (AD). Thus, the development of multitarget drugs which are involved in both pathways might represent a promising therapeutic strategy. Accordingly, reported here in is the discovery of 6‐amino‐4‐phenyl‐3,4‐dihydro‐1,3,5‐triazin‐2(1H)‐ones as the first class of molecules able to simultaneously modulate BACE‐1 and GSK‐3β. Notably, one triazinone showed well‐balanced in vitro potencies against the two enzymes (IC50 of (18.03±0.01) μM and (14.67±0.78) μM for BACE‐1 and GSK‐3β, respectively). In cell‐based assays, it displayed effective neuroprotective and neurogenic activities and no neurotoxicity. It also showed good brain permeability in a preliminary pharmacokinetic assessment in mice. Overall, triazinones might represent a promising starting point towards high quality lead compounds with an AD‐modifying potential. 相似文献
99.
Malondialdehyde (MDA) determination is the most widely used method for monitoring lipid peroxidation. Here, we describe an easy field-amplified sample injection (FASI) CE method with UV detection for the detection of free plasma MDA. MDA was detected within 8 min by using 200 mmol/L Tris phosphate pH 5.0 as running buffer. Plasma samples treated with ACN for protein elimination were directly injected on capillary without complex cleanup and/or sample derivatization procedures. Using electrokinetic injection, the detection limit in real sample was 3 nmol/L, thus improving of about 100-fold the LOD of the previous described methods based on CE. Precision tests indicate a good repeatability of our method both for migration times (CV = 1.11%) and for areas (CV = 2.05%). Moreover, a good reproducibility of intra- and inter-assay tests was obtained (CV = 2.55% and CV = 5.14%, respectively). Suitability of the method was tested by measuring MDA levels in 44 healthy volunteers. 相似文献
100.
Fleury BG Figueiredo L Marcoli MI Teixeira VL Ferreira AB Pinto AC 《Natural product communications》2011,6(5):667-672
The distribution of fatty acids in 13 species of macroalgae (Chlorophyta, Ochrophyta and Rhodophyta) and 1 seagrass (Spartina sp), collected on the Rio de Janeiro state coast was determined. The results were evaluated in search of correlations between the taxonomic and phylogenetic position of these macrophytes. Statistical analyses showed the effectiveness as taxonomic and phylogenetic markers of the distribution of the methyl fatty acid esters in these macrophytes. 相似文献