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101.
First-principles molecular dynamics (FPMD) simulations and static quantum chemical (QC) calculations are used to evaluate the tensile strengths, σ(c), of interfaces consisting of (0001) surfaces of α-Al(2)O(3) separated by small organic species. The evaluation of σ(c) with FPMD was achieved by performing simulations in which the simulation cell was extending in a direction normal to the fracture plane until rupture of the interface occurred. The static QC calculations employed an approach which treated fracture of the interface as a competition between uniform extension of the simulation cell and crack formation at the rupture site, which is analogous to that used in the construction of universal binding energy relationships. The results showed that the static QC calculations accurately reproduced the FPMD simulations with respect to tensile strength and the cell extension at which rupture occurred, provided that the rupture site employed in the static calculations matched the site at which rupture occurred during the FPMD simulations. A simple strategy for identifying the rupture site, even in complex systems containing many potential rupture sites, is proposed. Overall, the work extends the calculation of tensile strengths with static QC methods to highly heterogeneous interfaces, thus providing a computationally efficient alternative to demanding FPMD simulations for this purpose. 相似文献
102.
Ten coumarin derivatives containing(E)-methyl 2-(methoxyimino)-2-phenylacetate were synthesized and bioassayed.The compounds were identified by IR,~1H NMR and elemental analyses.The test results indicated that compound 5j(R~1 is methyl and R~2 is n-C_6H_(13)) was the optimal structure in this paper with good fungicidal activity against CDM(85%) at 6.25 mg/L concentration. 相似文献
103.
Serge Kokot 《中国化学快报》2011,22(5):591-594
The voltammetric behaviour of three 5-nitroimidazoles,metronidazole,tinidazole and ornidazole,was investigated,and a method was developed for the simultaneous determination of these compounds,based on their reduction at a hanging mercury drop electrode(HMDE) in pH 8.95 buffer with differential pulse voltammetric(DPV) approach.Well defined voltammetric waves with peak potentials of -692,-640 and -652 mV were observed for these compounds,respectively.It is difficult to determine them individually from their mixtures without preseparation,for their voltammetric peaks overlapped seriously,so the chemometrics were used to resolve the overlapped voltammogram and quantify the mixtures.The proposed method was successfully applied to the determination of three 5-nitroimidazoles in milk and honey samples. 相似文献
104.
105.
Shi Z Liu J Lin T Xia F Liu PN Lin N 《Journal of the American Chemical Society》2011,133(16):6150-6153
We investigated the thermodynamic processes of two-dimensional (2D) metallo-supramolecular self-assembly at molecular resolution using scanning tunneling microscopy and variable-temperature low-energy electron diffraction. On a Au(111) substrate, tripyridyl ligands coordinated with Cu in a twofold Cu-pyridyl binding mode or with Fe in a threefold Fe-pyridyl binding mode, forming a 2D open network structure in each case. The network structures exhibited remarkable thermal stability (600 K for the Cu-coordinated network and 680 K for the Fe-coordinated network). The Fe-pyridyl binding was selected thermodynamically as well as kinetically in self-assembly involving both modes. The selectivity can be effectively suppressed in a specifically designed self-assembly route. 相似文献
106.
Simultaneous Determination of Cimaterol, Salbutamol, Terbutaline and Ractopamine in Feed by SPE Coupled to UPLC 总被引:2,自引:0,他引:2
Chun Hua Qu Xian Liang Li Lei Zhang Cun Xian Xi Guo Ming Wang Nian Bing Li Hong Qun Luo 《Chromatographia》2011,73(3-4):243-249
An ultra performance liquid chromatography (UPLC) method was established for the simultaneous determination of cimaterol, salbutamol, terbutaline, and ractopamine in feed. Target compounds were extracted with methanol and centrifuged. The supernatant was then transferred and concentrated, and applied to a solid phase extraction MCX cartridge for clean-up before UPLC analysis. The calibration curves for the four ??-agonists were good linear in concentration range of 0.05?C1.0 ??g mL?1 with the correlation coefficients (r) over 0.999. The average recoveries were in the range of 90.1?C101.4% with relative standard deviation values lower than 8.0%. 相似文献
107.
Zhou X Peng F Wang H Yu H Fang Y 《Chemical communications (Cambridge, England)》2011,47(37):10323-10325
Novel carbon nitride polymer sensitized TiO(2) nanotube arrays with high photocatalytic activity and photoelectrochemical response under visible light irradiation are prepared by electrodeposition. 相似文献
108.
Wang W Wang S Hong Y Tang BZ Lin N 《Chemical communications (Cambridge, England)》2011,47(36):10073-10075
We studied the supramolecular assembly of a multifunctional ligand, cis-bis-terpyridine tetraphenyl ethylene, on a Cu(111) surface by low-temperature scanning tunneling microscopy (STM). Three distinctive supramolecular structures, metallacycles, propeller-shaped clusters and extended linear chains, are formed under specific assembly conditions owing to different inter-molecular binding modes of Cu-coordination, van der Waals interaction and hydrogen bonding, respectively. 相似文献
109.
Huang WT Shi Y Xie WY Luo HQ Li NB 《Chemical communications (Cambridge, England)》2011,47(27):7800-7802
Herein, we demonstrate the first use of a reduced graphene oxide (rGO)-organic dye nanoswitch for the label-free, sensitive and selective detection of Hg(2+) using bifunctional rGO as an effective nanoquencher and highly selective nanosorbent. Moreover, a reversible on-off INHIBIT rGO logic gate based on a cysteine-Hg(2+) system has also been designed. 相似文献
110.
In a recent paper, Nguyen et al. (2018) built a distributionally robust estimator for the precision matrix of the Gaussian distribution. The distributional uncertainty size is a key ingredient in the construction of this estimator. We develop a statistical theory which shows how to optimally choose the uncertainty size to minimize the associated Stein loss. Surprisingly, rather than the expected canonical square-root scaling rate, the optimal uncertainty size scales linearly with the sample size. 相似文献