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991.
Møller C Sprenger RR Stürup S Højrup P 《Analytical and bioanalytical chemistry》2011,401(5):1623-1633
Using insulin as a model protein for binding of oxaliplatin to proteins, various mass spectrometric approaches and techniques
were compared. Several different platinum adducts were observed, e.g. addition of one or two diaminocyclohexane platinum(II)
(Pt(dach)) molecules. By top-down analysis and fragmentation of the intact insulin–oxaliplatin adduct using nano-electrospray
ionisation quadrupole time-of-flight mass spectrometry (nESI-Q-ToF-MS), the major binding site was assigned to histidine5
on the insulin B chain. In order to simplify the interpretation of the mass spectrum, the disulphide bridges were reduced.
This led to the additional identification of cysteine6 on the A chain as a binding site along with histidine5 on the B chain.
Digestion of insulin–oxaliplatin with endoproteinase Glu-C (GluC) followed by reduction led to the formation of five peptides
with Pt(dach) attached. Identification of several of the binding sites was obtained using matrix-assisted laser desorption/ionization
(MALDI)-ToF-ToF-MS and liquid chromatography-nESI-Q-ToF-MS. Upon comparing the top-down and bottom-up approaches, the suitability
of the bottom-up approach for determining binding sites was questioned, as the release and possible re-association of Pt(dach)
were demonstrated upon enzymatic digestion. The associated advantages and disadvantages of ESI and MALDI were also pointed
out. 相似文献
992.
Mittelmaier S Fünfrocken M Fenn D Berlich R Pischetsrieder M 《Analytical and bioanalytical chemistry》2011,401(4):1183-1193
During heat sterilization of peritoneal dialysis solutions, glucose is partially transformed into glucose degradation products
(GDPs), which significantly reduce the biocompatibility of these medicinal products. Targeted α-dicarbonyl screening identified
glyoxal, methylglyoxal, 3-deoxyglucosone, 3,4-dideooxyglucosone-3-ene, glucosone, and 3-deoxygalactosone as the major six
GDPs with α-dicarbonyl structure. In the present study, an ultra-high-performance liquid chromatography method was developed
which allows the separation of all relevant α-dicarbonyl GDPs within a run time of 15 min after derivatization with o-phenylenediamine. Hyphenated diode array detection/tandem mass spectrometry detection provides very robust quantification
and, at the same time, unequivocal peak confirmation. Systematic evaluation of the derivatization process resulted in an optimal
derivatization period that provided maximal derivatization yield, minimal de novo formation (uncertainty range ±5%), and maximal
sample throughput. The limit of detection of the method ranged from 0.13 to 0.19 μM and the limit of quantification from 0.40
to 0.57 μM. Relative standard deviations were below 5%, and recovery rates ranged between 91% and 154%, dependent on the type
and concentration of the analyte (in 87 out of 90 samples, recovery rates were 100 ± 15%). The method was then applied for
the analysis of commercial peritoneal dialysis fluids (nine different product types, samples from three lots of each). 相似文献
993.
Krivec S Buchmayr M Detzel T Froemling T Fleig J Hutter H 《Analytical and bioanalytical chemistry》2011,400(3):649-657
The action of Na+ incorporation into thin insulating films and transport therein under influence of a bias voltage and temperature (BT stress)
is the subject of this work. Deposited onto highly n-doped Si wafers, the insulators get BT stressed and subsequently investigated by means of time-of-flight–secondary ion mass
spectrometry (ToF-SIMS). A thin PMMA film, spin-coated onto the insulator, serves as host matrix for a defined amount of Na+, provided via sodium triflate. Combining BT stress and ToF-SIMS depth profiling enables the unambiguous detection of Na+, incorporated into the insulating material. The insulators of interest vary in their nitride content: SiO2, SiOxNy, and Si3N4. For SiO2, it is shown that once a threshold BT stress is exceeded, Na+ gets quantitatively incorporated from PMMA into the underlying insulator, finally accumulating at the SiO2/Si interface. A quantitative assessment by combination of Butler–Volmer kinetics with hopping dynamics reveals activation
energies of E
a = 1.55 − 2.04 eV for Na+ transport in SiO2 with varying thickness. On the other hand, SiOxNy and Si3N4 films show a different Na+ incorporation characteristic in this type of experiment, which can be explained by the higher coordination of nitrogen and
hence the reduced Na+ permeability within these insulators. 相似文献
994.
We consider generalized potential operators with the kernel on bounded quasimetric measure space (X, μ, d) with doubling measure μ satisfying the upper growth condition μB(x, r) ? KrN, N ∈ (0, ∞). Under some natural assumptions on a(r) in terms of almost monotonicity we prove that such potential operators are bounded from the variable exponent Lebesgue space Lp(?)(X, μ) into a certain Musielak‐Orlicz space Lp(X, μ) with the N‐function Φ(x, r) defined by the exponent p(x) and the function a(r). A reformulation of the obtained result in terms of the Matuszewska‐Orlicz indices of the function a(r) is also given. © 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim 相似文献
995.
In this note, we address the following question: Which 1-formal groups occur as fundamental groups of both quasi-K?hler manifolds and closed, connected, orientable 3-manifolds. We classify all such groups, at the level of Malcev completions, and compute their coranks. Dropping the assumption on realizability by 3-manifolds, we show that the corank equals the isotropy index of the cup-product map in degree one. Finally, we examine the formality properties of smooth affine surfaces and quasi-homogeneous isolated surface singularities. In the latter case, we describe explicitly the positive-dimensional components of the first characteristic variety for the associated singularity link. 相似文献
996.
997.
Let L be a lattice. A function f:L→R (usually called evaluation) is submodular if f(x∧y)+f(x∨y)≤f(x)+f(y), supermodular if f(x∧y)+f(x∨y)≥f(x)+f(y), and modular if it is both submodular and supermodular. Modular functions on a finite lattice form a finite dimensional vector space. For finite distributive lattices, we compute this (modular) dimension. This turns out to be another characterization of distributivity (Theorem 3.9). We also present a correspondence between isotone submodular evaluations and closure operators on finite lattices (Theorem 5.5). This interplay between closure operators and evaluations should be understood as building a bridge between qualitative and quantitative data analysis. 相似文献
998.
Stefan Hetzl Alexander Leitsch Daniel Weller 《Annals of Pure and Applied Logic》2011,162(12):1001-1034
We define a generalization of the first-order cut-elimination method CERES to higher-order logic. At the core of lies the computation of an (unsatisfiable) set of sequents (the characteristic sequent set) from a proof π of a sequent S. A refutation of in a higher-order resolution calculus can be used to transform cut-free parts of π (the proof projections) into a cut-free proof of S. An example illustrates the method and shows that can produce meaningful cut-free proofs in mathematics that traditional cut-elimination methods cannot reach. 相似文献
999.
Arrangements of lines and pseudolines are important and appealing objects for research in discrete and computational geometry.
We show that there are at most 20.657> n22^{0.657\> n^{2}} simple arrangements of n pseudolines in the plane. This improves on previous work by Knuth who proved an upper bound of
3\binomn2 @ 20.792> n23^{\binom{n}{2}} \cong 2^{0.792\> n^{2}} in 1992 and the first author, who obtained 20.697> n22^{0.697\> n^{2}} in 1997. The argument uses surprisingly little geometry. The main ingredient is a lemma that was already central to the argument
given by Knuth. 相似文献
1000.
Antoine Gloria Stefan Neukamm 《Annales de l'Institut Henri Poincaré (C) Analyse Non Linéaire》2011,28(6):941
We prove under some general assumptions on elastic energy densities (namely, frame indifference, minimality at identity, non-degeneracy and existence of a quadratic expansion at identity) that homogenization and linearization commute at identity. This generalizes a recent result by S. Müller and the second author by dropping their assumption of periodicity. As a first application, we extend their Γ-convergence commutation diagram for linearization and homogenization to the stochastic setting under standard growth conditions. As a second application, we prove that the Γ-closure is local at identity for this class of energy densities. 相似文献