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21.
In this paper, the existence of periodic traveling wave solutions with a priori unknown velocity is considered for a coupled map lattice dynamical system. By trasforming our problem into one that involves polynomials, explicit 2- and 3-periodic traveling wave solutions are found, while the other solutions can be computed numerically. Since there does not seem to be any reports on explicit traveling wave solutions, we hope that our results will lead to the discovery of many others.  相似文献   
22.
This paper presents methods of determining the long-term stability of vitamin E emulsion and formation of microemulsions. Several emulsion systems formed by using anionic, zwitterionic and cationic surfactants have been studied in the presence and absence of NaCI. Several conclusions can be drawn: (1) by using UV absorption and particle size measurements, one may be able to predict the long-term stability of an emulsion or the possibility of forming a microemulsion by measuring the initial properties of an emulsion, (2) in order to form a stable vitamin E emulsion or microemulsion, the initial properties of the emulsion should have the following features : (a) the particle size is ≤ 200 nm, (b) the surfactant system has a saturation value ≥ 1 and (c) the surfactant system can dissolve a substantial amount of vitamin E without causing an increase of the emulsion droplet size and (3) the saturation value and the stability of many vitamin E emulsion systems can be increased by adding an optimum amount of NaCI.  相似文献   
23.
International Journal of Theoretical Physics - In this paper, we present a quantum key agreement (QKA) protocol with non-maximally entangled four-qubit cluster states. In our scheme, each...  相似文献   
24.
Phytochemical investigation of the EtOH extract of Euphorbia sieboldiana led to the isolation of four new oleanane‐type triterpenoids, (1β,2α,3β,19β)‐1,2,3,19‐tetrahydroxyolean‐12‐en‐28‐oic acid, (1β,3β,19β)‐1,3,19‐trihydroxyolean‐12‐en‐28‐oic acid, (1β,2α,3β,16β,19β)‐1,2,3,16,19‐pentahydroxyolean‐12‐en‐28‐oic acid, and (1β,2α,3β,19β,23)‐1,2,3,19,23‐pentahydroxyolean‐12‐en‐28‐oic acid, along with 16 known compounds. Their structures were established by extensive 1D‐ and 2D‐NMR, as well as other spectral analyses. Biological evaluation of the four new triterpenoids revealed potent cytotoxic activities against HeLa and Hep‐G2 cells.  相似文献   
25.
Two-component systems (TCS) are signaling machinery that consist of a histidine kinases (HK) and response regulator (RR). When an environmental change is detected, the HK phosphorylates its cognate response regulator (RR). While cognate interactions were considered orthogonal, experimental evidence shows the prevalence of crosstalk interactions between non-cognate HK–RR pairs. Currently, crosstalk interactions have been demonstrated for TCS proteins in a limited number of organisms. By providing specificity predictions across entire TCS networks for a large variety of organisms, the ELIHKSIR web server assists users in identifying interactions for TCS proteins and their mutants. To generate specificity scores, a global probabilistic model was used to identify interfacial couplings and local fields from sequence information. These couplings and local fields were then used to construct Hamiltonian scores for positions with encoded specificity, resulting in the specificity score. These methods were applied to 6676 organisms available on the ELIHKSIR web server. Due to the ability to mutate proteins and display the resulting network changes, there are nearly endless combinations of TCS networks to analyze using ELIHKSIR. The functionality of ELIHKSIR allows users to perform a variety of TCS network analyses and visualizations to support TCS research efforts.  相似文献   
26.
Two-dimensional surface-enhanced Raman scattering(SERS) substrates have drawn intense attention due to their excellent spectral reproducibility, high uniformity and perfect anti-interference ability. However, the inferior detection sensitivity and low enhancement have limited the practical application of two-dimensional SERS substrates. To address this issue, we propose that the interaction between the MoTe_2 substrate and the analyte rhodamine 6 G molecules could be remarkably enhanced by the introduced p-doping effect and lattice distortion of MoTe_2 via hydrogen plasma treatment. After the treatment, the SERS is greatly improved, the enhancement factor of probe molecules reaches 1.83 × 10~6 as well as the limit of detection concentration reaches 10-13 M.This method is anticipated to afford new enhancement probability for other 2D materials, even non-metal oxide semiconductor SERS substrates.  相似文献   
27.
Hydridic-to-protonic dihydrogen bonds (DHBs) are involved in comprehensive structural and energetic evolution, and significantly affect reactivity and selectivity in solution and solid states. Grand challenges exist in understanding DHBs’ bonding nature and strength, and how to harness DHBs. Herein we launched a combined photoelectron spectroscopy and multiscale theoretical investigation using monohydrated closo-dodecaborate clusters B12X122−·H2O (X = H, F, I) to address such challenges. For the first time, a consistent and unambiguous picture is unraveled demonstrating that B–H⋯H–O DHBs are superior to the conventional B–X⋯H–O HBs, being 1.15 and 4.61 kcal mol−1 stronger than those with X = F and I, respectively. Energy decomposition analyses reveal that induction and dispersion terms make pronounced contributions resulting in a stronger B–H⋯H–O DHB. These findings call out more attention to the prominent roles of DHBs in water environments and pave the way for efficient and eco-friendly catalytic dihydrogen production based on optimized hydridic-to-protonic interactions.

A joint gas-phase ion spectroscopic and multiscale theoretical study reveals unequivocally the predominance of the hydridic-to-protonic dihydrogen bond over the prototypical strong hydrogen bond in monohydrated dodecaborate clusters.  相似文献   
28.
A new algorithm for finding the inverse of a nonsingular scaled factor circulant matrix is presented by the Euclid's algorithm. Extension is made to compute the group inverse and the Moore-Penrose inverse of the singular scaled factor circulant matrix. Numerical examples are presented to demonstrate the implementation of the proposed algorithm.  相似文献   
29.
Protosappanoside D (PTD) is a new component isolated from the extract of Caesalpinia decapetala for the first time. Its structure was identified as protosappanin B-3-O-β-D-glucoside by 1H-NMR, 13C-NMR, 2D-NMR and MS techniques. To date, the pharmacological activities, metabolism or pharmacokinetics of PTD has not been reported. Therefore, this research to study the anti-inflammatory activity of PTD was investigated via the LPS-induced RAW264.7 cells model. At the same time, we also used the UHPLC/Q Exactive Plus MS and UPLC-MS/MS methods to study the metabolites and pharmacokinetics of PTD, to calculate its bioavailability for the first time. The results showed that PTD could downregulate secretion of the pro-inflammatory cytokines. In the metabolic study, four metabolites were identified, and the primary degradative pathways in vivo involved the desaturation, oxidation, methylation, alkylation, dehydration, degradation and desugarization. In the pharmacokinetic study, PTD and its main metabolite protosappanin B (PTB) were measured after oral and intravenous administration. After oral administration of PTD, its Tmax was 0.49 h, t1/2z and MRT(0–t) were 3.47 ± 0.78 h and 3.06 ± 0.63 h, respectively. It shows that PTD was quickly absorbed into plasma and it may be eliminated quickly in the body, and its bioavailability is about 0.65%.  相似文献   
30.
Aluminum is a kind of metal that we often encounter. It can also be absorbed by the human body invisibly and will affect our bodies to a certain extent, e.g., by causing symptoms associated with Alzheimer’s disease. Therefore, the detection of aluminum is particularly important. The methods to detect metal ions include precipitation methods and electrochemical methods, which are cumbersome and costly. Fluorescence detection is a fast and sensitive method with a low cost and non-toxicity. Traditional fluorescent nanomaterials have a high cost, high toxicity, and cause harm to the human body. Graphene quantum dots are a new type of fluorescent nanomaterials with a low cost and non-toxicity that can compensate for the defects of traditional fluorescent nanomaterials. In this paper, c-GQDs and o-GQDs with good performance were prepared by a bottom-up hydrothermal method using o-phenylenediamine as a precursor and citric acid or boric acid as modulators. They have very good optical properties: o-GQDs exhibit orange fluorescence under UV irradiation, while c-GQDs exhibits cyan fluorescence. Then, different metal ions were used for ion detection, and it was found that Al3+ had a good quenching effect on the fluorescence of the o-GQDs. The reason for this phenomenon may be related to the strong binding of Al3+ ions to the N and O functional groups of the o-GQDs and the rapid chelation kinetics. During the chelation process, the separation of o-GQDs’ photoexcited electron hole pairs leads to their rapid electron transfer to Al3+, in turn leading to the occurrence of a fluorescence-quenching phenomenon. In addition, there was a good linear relationship between the concentration of the Al3+ ions and the fluorescence intensity, and the correlation coefficient of the linear regression equation was 0.9937. This illustrates the potential for the wide application of GQDs in sensing systems, while also demonstrating that Al3+ sensors can be used to detect Al3+ ions.  相似文献   
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