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81.
A random effects probit model is developed for the case in which the same units are sampled repeatedly at each level of an independent variable. Because the observed proportions may be correlated under these conditions, estimating their trend with respect to the independent variable is no longer a standard problem for probit, logit or loglinear analysis. Using a qualitative analogue of a random regressions model, we employ instead marginal maximum likelihood to estimate the average latent trend line. Likelihood ratio tests of the hypothesis of no trend in the average line, and the hypothesis of no differences in average trend lines between experimental treatments, are proposed. We illustrate the model both with simulated data and with observed data from a clinical experiment in which psychiatric patients on two drug therapies are rated on five occasions for the presence or absence of symptoms.Supported by a grant from the MacArthur Foundation and National Science Foundation Grant BNS85-11774.The authors are indebted to James Heckman for calling our attention to the Clark algorithm. 相似文献
82.
83.
We study the semantic relationship between pairs of nouns of concrete objects such as “HORSE - SHEEP” and “SWING - MELON” and how this relationship activity is reflected in EEG signals. We collected 18 sets of EEG records; each set containing 150 events of stimulation. In this work we focus on feature extraction algorithms. Particularly, we highlight Common Spatial Pattern (CSP) as a method of feature extraction. Based on these latter, different classifiers were trained in order to associate a set of signals to a previously learned human answer, pertaining to two classes: semantically related, or not semantically related. The results of classification accuracy were evaluated comparing with other four methods of feature extraction, and using classification algorithms from five different families. In all cases, classification accuracy was benefited from using CSP instead of FDTW, LPC, PCA or ICA for feature extraction. Particularly with the combination CSP-Naïve Bayes we obtained the best average precision of 84.63%. 相似文献
84.
肿瘤临床治疗中应关注肝脏 总被引:1,自引:0,他引:1
杨永平 《医学与哲学(人文社会医学版)》2011,(2):13-15
抗肿瘤细胞毒性药物有不同程度毒副作用,有些严重毒副反应是限制药物剂量或使用的直接原因。肝脏是药物代谢的主要器官,也是药物损伤的主要靶器官。随着临床肿瘤治疗关注治疗带来的副作用与关注疗效同等重要的发展,本文对抗肿瘤细胞毒性药物与肝损伤、发生机制、诊断、分型和临床治疗进展进行了阐述。 相似文献
85.
A web-based software model was developed as an example for data mining in aphasiology. It is used for educating medical and engineering students. It is based upon a database of 254 aphasic patients which contains the diagnosis of the aphasia type, profiles of an aphasia test battery (Aachen Aphasia Test), and some further clinical information. In addition, the cerebral lesion profiles of 147 of these cases were standardized by transferring the coordinates of the lesions to a 3D reference brain based upon the ACPC coordinate system. Two artificial neural networks were used to perform a classification of the aphasia type. First, a coarse classification was achieved by using an assessment of spontaneous speech of the patient which produced correct results in 87% of the test cases. Data analysis tools were used to select four features of the 30 available test features to yield a more accurate diagnosis. This classifier produced correct results in 92% of the test cases. The neural network approach is similar to grouping performed in group studies, while the nearest-neighbor method shows a design more similar to case studies. It finds the neurolinguistic and the lesion data of patients whose AAT profiles are most similar to the user's input. This way lesion profiles can be compared to each other interindividually. The Aphasia Diagnoser is available on the Web address http://fuzzy.iau.dtu.dk/aphasia.nsf and thus should facilitate a discussion about the reliability and possibilities of data-mining techniques in aphasiology. 相似文献
86.
87.
For the exploratory analysis of a matrix of proximities or (dis)similarities between objects, one often uses cluster analysis
(CA) or multidimensional scaling (MDS). Solutions resulting from such analyses are sometimes interpreted using external information
on the objects. Usually the procedures of CA, MDS and using external information are carried out independently and sequentially,
although combinations of two of the three procedures (CA and MDS, or multidimensional scaling and using external information)
have been proposed in the literature. The present paper offers a procedure that combines all three procedures in one analysis,
using a model that describes a partition of objects with cluster centroids represented in a low-dimensional space, which in
turn is related to the information in the external variables. A simulation study is carried out to demonstrate that the method
works satisfactorily for data with a known underlying structure. Also, to illustrate the method, it is applied to two empirical
data sets. 相似文献
88.
Liechty, Pieters & Wedel (2003) developed a hidden Markov Model (HMM) to identify the states of an attentional process in an advertisement viewing task. This work is significant because it demonstrates the benefits of stochastic modeling and Bayesian estimation in making inferences about cognitive processes based on eye movement data. One limitation of the proposed approach is that attention is conceptualized as an autonomous random process that is affected neither by the overall layout of the stimulus nor by the visual information perceived during the current fixation. An alternative model based on the input-output hidden Markov model (IOHMM; Bengio, 1999) is suggested as an extension of the HMM. The need for further studies that validate the HMM classification results is also discussed. 相似文献
89.
90.
Ladislav Tondl 《Journal for General Philosophy of Science》1998,29(2):245-264
The paper justifies the concept of “thematic structure” or “order of knowledge” over the traditional “classification of sciences”
due to the uncertainty of many classification criteria. The thematic structure of science has, of course, various levels and
various dimensions. Arguments against any forms of separating the humanities from sciences in the traditional sense of the
term are presented and discussed. Equally unacceptable are attempts at sharp separation of technical disciplines and humanities.
The thematic structure of humanities is not created by some material aspects but rather through the interest — or problem-oriented
aspects. In addition to the natural sciences and the humanities there exists an important sphere of sciences on artefacts
or, using the term by H. Simon, the sciences of the artificial. For the contemporary research activities is typical what could
be denoted as “interdisciplinary or multidisciplinary complex.” The paper traces a set of epistemological criteria for the
justification of the relative independence of a scientific discipline.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献