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排序方式: 共有9819条查询结果,搜索用时 140 毫秒
991.
Zhang L Xu J Sun L Ma J Yang K Liang Z Zhang L Zhang Y 《Analytical and bioanalytical chemistry》2011,399(10):3399-3405
In this study, zirconium oxide (ZrO2) aerogel was synthesized via a green sol–gel approach, with zirconium oxychloride, instead of the commonly used alkoxide
with high toxicity, as the precursor. With such material, phosphopeptides from the digests of 4 pmol of β-casein with the
coexistence of 100 times (mol ratio) BSA could be selectively captured, and identified by MALDI-TOF MS. Due to the large surface
area (416.0 m2 g−1) and the mesoporous structure (the average pore size of 10.2 nm) of ZrO2 aerogel, a 20-fold higher loading capacity for phosphopeptide, YKVPQLEIVPN[pS]AEER (MW 1952.12), was obtained compared to
that of commercial ZrO2 microspheres (341.5 vs. 17.87 mg g−1). The metal oxide aerogel was further applied in the enrichment of phosphopeptides from 100 ng nonfat milk, and 17 phosphopeptides
were positively identified, with a 1.5-fold improvement in phosphopeptide detection compared with previously reported results.
These results demonstrate that ZrO2 aerogel can be a powerful enrichment material for phosphoproteome study. 相似文献
992.
Sun L Tao D Han B Ma J Zhu G Liang Z Shan Y Zhang L Zhang Y 《Analytical and bioanalytical chemistry》2011,399(10):3387-3397
The solubility and digestion efficiency are two crucial factors that might affect the identification of integral membrane
proteins (IMPs). In this work, 1% (v/v) ionic liquid (IL), 1-butyl-3-methyl imidazolium tetrafluoroborate (BMIM BF4), added in NH4HCO3 buffer (pH 8.3), was applied as a sample preparation buffer for IMPs analysis. Compared to the commonly used sodium dodecyl
sulfate and methanol methods, the number of identified IMPs from rat brain by microcolumn reversed phase liquid chromatography
(μRPLC)-electrospray ionization tandem mass spectrometry (ESI-MS/MS) was improved by over three times, which might be due
to the fact that BMIM BF4 offered high solubilizing ability for IMPs and good compatibility for tryptic digestion. Furthermore, compared to Rapigest
and urea methods, with BMIM BF4 method, the number of identified IMPs from rat brain could be improved 25% and 80%, respectively, which might be contributed
to the good solubilizing ability and high thermal stability of such IL. With the sample treated by BMIM BF4 method, by 2D-nanoSCX-RPLC-ESI-MS/MS, 1,450 non-redundant proteins and 7,978 unique peptides were identified from rat brain,
and 418 proteins contained at least one predicted transmembrane domain, with false discovery rates of less than 1% for peptide
identification, and at least two identified unique peptides per protein. All these results demonstrate that the BMIM BF4 method is of high potential for the large-scale identification of IMPs. 相似文献
993.
Electrospinning is known to be a highly versatile method to produce nanofibers, and several techniques have been developed
to align nanofibers. In this paper, poly(vinyl alcohol) (PVA), poly(vinylpyrrolidone) (PVP), poly(propylene carbonate) (PC),
poly(ethylene oxide) (PEO), PVA/Chitosan and PVA/Fe3O4 uniaxially aligned ultrafine fibers were obtained with electrospinning method by adding another electric field in the collection
area. Alignment of the nanofibers was characterized by the use of digital cameras and field emission scanning electron microscopy,
polarized Fourier transform infrared spectroscopy (FTIR), and wideangle X-ray diffraction (XRD). The mechanism of fiber alignment
was investigated as well. 相似文献
994.
This paper is concerned with the stochastic optimal control problem of jump diffusions. The relationship between stochastic
maximum principle and dynamic programming principle is discussed. Without involving any derivatives of the value function,
relations among the adjoint processes, the generalized Hamiltonian and the value function are investigated by employing the
notions of semijets evoked in defining the viscosity solutions. Stochastic verification theorem is also given to verify whether
a given admissible control is optimal. 相似文献
995.
996.
997.
Wu J Xie L Li Y Wang H Ouyang Y Guo J Dai H 《Journal of the American Chemical Society》2011,133(49):19668-19671
We investigated the chlorine plasma reaction with graphene and graphene nanoribbons and compared it with the hydrogen and fluorine plasma reactions. Unlike the rapid destruction of graphene by hydrogen and fluorine plasmas, much slower reaction kinetics between the chlorine plasma and graphene were observed, allowing for controlled chlorination. Electrical measurements on graphene sheets, graphene nanoribbons, and large graphene films grown by chemical vapor deposition showed p-type doping accompanied by a conductance increase, suggesting nondestructive doping via chlorination. Ab initio simulations were performed to rationalize the differences in fluorine, hydrogen, and chlorine functionalization of graphene. 相似文献
998.
Chen R Wang L Xiong C Zhou Y Zhen C Zhang N Tang Y Zhou X Wang J Nie Z Chen Y 《The Analyst》2011,136(18):3809-3814
Electrosonic spray ionization (ESSI) is a derivative technique of electrospray ionization (ESI) for mass spectrometry (MS) in which droplets are charged in the course of sonic spray. In this study, we applied ESSI MS to direct analysis of oligosaccharides and alpha hydroxy acids (AHAs) in fruits. The components were extracted from fruit fleshes by a feasible method prior to ESSI MS analysis, but the fruit juices were analyzed without further pretreatment. The results demonstrate that mainly alkali metal adducts of oligosaccharides are favorably produced in positive ion mode, while deprotonated AHAs and oligosaccharides are produced in negative ion mode. Compared with mass spectra obtained using electrospray droplet impact/secondary ion mass spectrometry (EDI/SIMS), mass spectra using ESSI make the identification of oligosaccharides more straightforward in positive ion mode than in negative ion mode. 相似文献
999.
A fast and direct competitive biomimetic enzyme‐linked immunosorbent assay (BELISA) method was developed for the determination of methimazole (MMZ) in urine sample based on a molecularly imprinted film as an artificial antibody. This is the first example to monitor methimazole with a direct competitive biomimetic enzyme‐linked immunosorbent assay (BELISA) method. The imprinted film was directly synthesized on the well surface of MaxiSorp polystyrene 96‐well plate and characterized. The results showed that it exhibited an antibody‐like binding ability, rapid adsorption speed, high stability, which was particularly advantageous and suitable for BELISA development. The BELISA method established in this paper had a higher selectivity for MMZ than for the structurally related compounds and the IC50 (calculated as the concentration giving 50% inhibition of color development) and the detection limit values under optimized experimental conditions were 70 ± 4 μg L‐1 and 0.9 ± 0.04 μg L‐1, respectively. The method was applied to the determination of MMZ in spiked urine sample with excellent recoveries ranging from 90% to 95%, and the imprinted film was able to be reused for 20 times without loss of sensitivity. The results obtained by BELISA correlated well with that obtained by the high performance liquid chromatography (HPLC) method. 相似文献
1000.
All-atomic molecular dynamics simulations have been performed to study the interfacial structural and dynamical properties of passivated gold nanoparticles in supercritical carbon dioxide (scCO(2)). Simulations were conducted for a 55-atom gold nanocore with thiolated perfluoropolyether as the packing ligands. The effect of solvent density and surface coverage on the structural and dynamical properties of the self-assembly monolayer (SAM) has been discussed. The simulation results demonstrate that the interface between nanoparticle and scCO(2) solvent shows a depletion region due to the preclusion of SAM. The presence of scCO(2) solvent around the passivated Au nanoparticle can lead to an enhanced extension of the surface SAM. Under full coverage, the structure and conformation of SAM are insensitive to the density change of scCO(2) fluid. This simulation results clarify the microscopic solvation mechanism of passivated nanoparticles in supercritical fluid medium and is expected to be helpful in understanding the scCO(2)-based nanoparticle dispersion behavior. 相似文献