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991.
992.
Claudia Heidel Marion Tichomirowa Jörg Matschullat 《Isotopes in environmental and health studies》2013,49(4):339-354
To pinpoint the origin and mixing processes of mine waters, different mine water types from the polymetallic sulphide ore deposit ‘Himmelfahrt Fundgrube’ (Freiberg, Germany) were analysed by thermal ionisation mass spectrometry using lead and strontium isotope ratios. Results show that the lead isotope composition of different mine waters results from a mixture of at least two sources: released lead from oxidised sulphide ores (mainly galena) and anthropogenic lead from groundwater. Furthermore, there are indications for an additional lead source. Strontium isotopes in mine waters identify at least three different sources: released strontium from weathered host rock (Grey Gneisses), released strontium from weathered gangue carbonates, and probably strontium from anthropogenic inputs. Contrary to former oxygen and sulphur isotope studies, strontium isotope compositions as well as hydrochemical parameters show the important role of gangue carbonates as an element source in mine waters. 相似文献
993.
For nonautonomous linear equations in a Banach space admitting a nonuniform version of exponential contraction, we give an optimal characterization of the exponential behavior in terms of strict Lyapunov sequences. In particular, we construct explicitly strict Lyapunov sequences for each exponential contraction. We also consider the particular case of quadratic Lyapunov functions, and we use the corresponding characterization of the exponential behavior in terms of these functions to show that the stability of an exponential contraction persists under sufficiently small perturbations. 相似文献
994.
We propose a parametric model for a bivariate stable Lévy process based on a Lévy copula as a dependence model. We estimate the parameters of the full bivariate model by maximum likelihood estimation. As an observation scheme we assume that we observe all jumps larger than some ε>0 and base our statistical analysis on the resulting compound Poisson process. We derive the Fisher information matrix and prove asymptotic normality of all estimates when the truncation point ε→0. A simulation study investigates the loss of efficiency because of the truncation. 相似文献
995.
Clavijo CF Hoffman KL Thomas JJ Carvalho B Chu LF Drover DR Hammer GB Christians U Galinkin JL 《Analytical and bioanalytical chemistry》2011,400(3):715-728
Opioids such as morphine are the cornerstone of pain treatment. The challenge of measuring the concentrations of morphine
and its active metabolites in order to assess human pharmacokinetics and monitor therapeutic drugs in children requires assays
with high sensitivity in small blood volumes. We developed and validated a semi-automated LC-MS/MS assay for the simultaneous
quantification of morphine and its active metabolites morphine 3β-glucuronide (M3G) and morphine 6β-glucuronide (M6G) in human
plasma and in dried blood spots (DBS). Reconstitution in water (DBS only) and addition of a protein precipitation solution
containing the internal standards were the only manual steps. Morphine and its metabolites were separated on a Kinetex 2.6-μm
PFP analytical column using an acetonitrile/0.1% formic acid gradient. The analytes were detected in the positive multiple
reaction mode. In plasma, the assay had the following performance characteristics: range of reliable response of 0.25–1000 ng/mL
(r
2 > 0.99) for morphine, 1–1,000 ng/mL (r
2 > 0.99) for M3G, and 2.5–1,000 ng/mL for M6G. In DBS, the assay had a range of reliable response of 1–1,000 ng/mL (r
2 > 0.99) for morphine and M3G, and of 2.5–1,000 ng/mL for M6G. For inter-day accuracy and precision for morphine, M3G and
M6G were within 15% of the nominal values in both plasma and DBS. There was no carryover, ion suppression, or matrix interferences.
The assay fulfilled all predefined acceptance criteria, and its sensitivity using DBS samples was adequate for the measurement
of pediatric pharmacokinetic samples using a small blood of only 20–50 μL. 相似文献
996.
Karioti A Furlan C Vincieri FF Bilia AR 《Analytical and bioanalytical chemistry》2011,399(4):1715-1723
In the present study, a method based on liquid chromatography with diode array detection (HPLC-DAD) coupled to an electrospray ionisation (ESI) interface was developed for the determination of the constituents in the aqueous preparations of Viola odorata L. flowering tops. The developed assay was fast, simple and effective and permitted the quality control of the preparations. The aim of this work was to assess the qualitative and quantitative profile of the investigated preparations, which find until today wide applications in food and cosmetic industry, and to propose a validated method for their quality control. Characteristic constituents of V. odorata flowers are considered to be the anthocyanins; however, a detailed literature research showed that data concerning their chemical content are scarce. HPLC-DAD-ESI-MS analyses supported by extensive preparative chromatographic investigations and 2D NMR analyses revealed the predominance of complex flavonol glycosides and permitted the complete characterisation of the content of V. odorata preparations. This is the first report of detailed analysis of the chemical composition of V. odorata flowers. 相似文献
997.
Claudia Malvenuto 《Journal of Combinatorial Theory, Series A》2011,118(4):1322-1333
Let D be the set of isomorphism types of finite double partially ordered sets, that is sets endowed with two partial orders. On ZD we define a product and a coproduct, together with an internal product, that is, degree-preserving. With these operations ZD is a Hopf algebra. We define a symmetric bilinear form on this Hopf algebra: it counts the number of pictures (in the sense of Zelevinsky) between two double posets. This form is a Hopf pairing, which means that product and coproduct are adjoint each to another. The product and coproduct correspond respectively to disjoint union of posets and to a natural decomposition of a poset into order ideals. Restricting to special double posets (meaning that the second order is total), we obtain a notion equivalent to Stanley's labelled posets, and a Hopf subalgebra already considered by Blessenohl and Schocker. The mapping which maps each double poset onto the sum of the linear extensions of its first order, identified via its second (total) order with permutations, is a Hopf algebra homomorphism, which is isometric and preserves the internal product, onto the Hopf algebra of permutations, previously considered by the two authors. Finally, the scalar product between any special double poset and double posets naturally associated to integer partitions is described by an extension of the Littlewood-Richardson rule. 相似文献
998.
999.
1000.
Röwer C Koy C Hecker M Reimer T Gerber B Thiesen HJ Glocker MO 《Journal of the American Society for Mass Spectrometry》2011,22(3):440-456
Early diagnosis as well as individualized therapies are necessary to reduce the mortality of breast cancer, and personalized
patient care strategies rely on novel prognostic or predictive factors. In this study, with six breast cancer patients, 2D
gel analysis was applied for studying protein expression differences in order to distinguish invasive ductal breast carcinoma,
the most frequent breast tumor subtype, from control samples. In total, 1203 protein spots were assembled in a 2D reference
gel. Differentially abundant spots were subjected to peptide mass fingerprinting for protein identification. Twenty proteins
with their corresponding 38 differentially expressed 2D gel spots were contained in our previously reported proteome signature,
suggesting that distinct protein forms were contributing. In-depth MS/MS measurements enabled analyses of protein structure
details of selected proteins. In protein spots that significantly contributed to our signature, we found that glyceraldehyde-3-phosphate
dehydrogenase was N-terminally truncated, pyruvate kinase M2 and nucleoside diphosphate kinase A but not other isoforms of
these proteins were of importance, and nucleophosmin phosphorylation at serine residues 106 and 125 were clearly identified.
Principle component analysis and hierarchical clustering with normalized quantitative data from the 38 spots resulted in accurate
separation of tumor from control samples. Thus, separation of tissue samples as in our initial proteome signature could be
confirmed even with a different proteome analysis platform. In addition, detailed protein structure investigations enabled
refining our proteome signature for invasive ductal breast carcinoma, opening the way to structure-/function studies with
respect to disease processes and/or therapeutic intervention. 相似文献