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21.
CONTINUATIONMETHODOFNONLINEARINTEGRALEQUATIONS¥YANGFenghang;SUNJing(DepartmentofMathematics,TianjinUniversity,Tianiin300072,C...  相似文献   
22.
China is experienciug from serious water issues. There are many differences among the Nine Major Rivers basins of China in the construction of dikes, reservoirs, floodgates, flood discharge projects, flood diversion projects, water ecological constructions, water conservancy management, etc. The shadow prices of water resources for Nine Major Rivers can provide suggestions to the Chinese goverument. This article develops a dynamic shadow prices approach based on a multipeziod input-output optimizing model. Unlike previous approaches, the new model is based on the dynamic computable general equilibrium (DCGE) model to solve the problem of marginal long-term prices of water resources. First, definitions and algorithms of DCGE are elaborated. Second, the results of shadow prices of water resources for Nine Major Rivers in 1949-2050 in China using the National Water Conservancy input-holdiug-out in table for Nine Major Rivers in 1999 are listed. A conclusion of this article is that the shadow prices of water resources for Nine Major Rivers are largely based on the extent of scarcity. Selling prices of water resources should be revised via the usage of parameters representing shadow prices.  相似文献   
23.
In this paper, we present a modular incremental statistical model for English full parsing.Unlike other full parsing approaches in which the analysis of the sentence is a uniform process,our model separates the full parsing into shallow parsing and sentence skeleton parsing. In shallow parsing, we finish POS tagging, Base NP identification, prepositional phrase attachment and sub-ordinate clause identification. In skeleton parsing, we use a layered feature-oriented statistical method. Modularity possesses the advantage of solving different problems in parsing with corre-sponding mechanisms. Feature-oriented rule is able to express the complex lingual phenomena at the key point if needed. Evaluated on Penn Treebank corpus, we obtained 89.2 % precision and 89.8% recall.  相似文献   
24.
In the present work, Si C ceramics was fabricated with Al N using B_4 C and C as sintering aids by a solid-state pressureless-sintered method. The effects of Al N contents on the densification, mechanical properties, phase compositions, and microstructure evolutions of as-obtained Si C ceramics were thoroughly investigated. Al N was found to promote further densification of the Si C ceramics due to its evaporation over 1800 °C,transportation, and solidification in the pores resulted from Si C grain coarsening. The highest relative density of 99.65% was achieved for Si C sample with 15.0 wt% Al N by the pressureless-sintered method at 2130 °C for 1 h in Ar atmosphere. Furthermore, the fracture mechanism for Si C ceramics containing Al N tended to transfer from single transgranular fracture mode to both transgranular fracture and intergranular fracture modes when the sample with 30.0 wt% Al N sintered at 1900 °C for 1 h in Ar. Also, Si C ceramics with 30.0 wt% Al N exhibited the highest fracture toughness of 5.23 MPa m~(1/2) when sintered at 1900 °C.  相似文献   
25.
To systematically investigate the kinetics and formation mechanisms of intragranular ferrite (IGF), isothermal heat treatment in the temperature range of 450℃ to 600℃ with holding for 30 s to 300 s, analysis of the corresponding microstructures, and observation of the precipitated particles were conducted in V-N microalloyed 600 MPa high strength rebar steel. The potency of V(C,N) for IGF nucleation was also analyzed statistically. The results show that the dominant microstructure transforms from bainite (B) and acicular ferrite (AF) to grain boundary ferrite (GBF), intragranular polygonal ferrite (IPF), and pearlite (P) as the isothermal temperature increases from 450℃ to 600℃. When the holding time at 600℃ is extended from 30 s to 60 s, 120 s, and 300 s, the GBF content ranges from 6.0vol% to 6.5vol% and the IPF content increases from 0.5vol% to 2.8vol%, 13.1vol%, and 13.5vol%, respectively, because the ferrite transformation preferentially occurs at the grain boundaries and then occurs at the austenite grains. Notably, V(C,N) particles are the most effective nucleation site for the formation of IPF, accounting for 51% of the said formation.  相似文献   
26.
In this paper,Berenger's perfectly matched layer(PML)absorbing boundary condition for electromagnetic waves is introduced as the truncation area of the computational domain to absorb one-dimensional acoustic wave for the scheme of acoustical wave propagator(AWP).To guarantee the efficiency of the AWP algorithm,a regulated propagator matrix is derived in the PML medium.Numerical simulations of a Gaussian wave packet propagating in one-dimensional duct are carried out to illustrate the efficiency of the combination of PML and AWP.Compared with the traditional smoothing truncation windows technique of AWP,this scheme shows high computational accuracy in absorbing acoustic wave when the acoustical wave arrives at the computational edges.Optimal coefficients of the PML configurations are also discussed.  相似文献   
27.
Based on high-throughput data, numerous algorithms have been designed to find functions of novel proteins. However, the effectiveness of such algorithms is currently limited by some fundamental factors, including (1) the low a-priori probability of novel proteins participating in a detailed function; (2) the huge false data present in high-throughput datasets; (3) the incomplete data coverage of functional classes; (4) the abundant but heterogeneous negative samples for training the algorithms; and (5) the lack of detailed functional knowledge for training algorithms. Here, for partially characterized proteins, we suggest an approach to finding their finer functions based on protein interaction sub-networks or gene expression patterns, defined in function-specific subspaces. The proposed approach can lessen the above-mentioned problems by properly defining the prediction range and functionally filtering the noisy data, and thus can efficiently find proteins’ novel functions. For thousands of yeast and human proteins partially characterized, it is able to reliably find their finer functions (e.g., the translational functions) with more than 90% precision. The predicted finer functions are highly valuable both for guiding the follow-up wet-lab validation and for providing the necessary data for training algorithms to learn other proteins.  相似文献   
28.
Photosensitized splitting of cis-syn 1,3-dimethyluracil dimer by tryptophan (Trp) and its peptides (Trp-Tyr and Trp-Phe) is studied by fluorescence quenching experiments and irradiation experiments.It reveals that 1,3-dimethyluracil dimer is mainly split by e?-?aq resulting from two-photon ionization of Trp and its peptides under irradiation with light (λ>290 nm).Moreover,the excited singlet state of Trp and its peptides can transfer an electron to the dimer,which splits and gives two pyrimidines.In addition,because of its lower oxidative potential,the excited triplet state of Trp-Tyr can also split the dimer via transfering an electron to the dimer.  相似文献   
29.
A 2-D cyclic variation of integrated backscatter (CVIB) imaging method was established for detecting myocardial ischemia. To demonstrate the feasibility and validity of this method, animal experiments were conducted. Acute myocardial ischemia was induced by occluding left anterior descending coronary artery in 10 anesthetized open-chest dogs. While scanning the normal hearts and the ischemic hearts with a B scanner, digital radiofrequency data were acquired by a real-time acquisition system in synchronism. The offline analysis to the radio-frequency signal with the 2-D CVIB imaging method was performed to verify the consistency between the imaging result and the design of the experiment. In addition, 4 dogs in experiment were treated with the heart pacemaker in order to investigate the influence of changing in heart rate on the detection of ischemic myocardium with the proposed method. The experimental result showed that the 2-D CVIB imaging method succeeded in detecting the ischemic myocardium and is a new non-invasive way for the cardiologists to both quantitatively and visually evaluate the contractile performance of the myocardium.  相似文献   
30.
In this paper, reliability of some typical non-Markov repairable systems, including series systems, m-out-of- n or majority vote systems, and n : m cross-strapping standby redundant systems with general repair-time distribution, are studied by applying the generalized Markov renewal process (GMRP). The stochastic behavior of the typical systems is analyzed here. Formulas for mean time to first system failure, MTBF, MTTR, and availability are then developed.  相似文献   
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