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排序方式: 共有344条查询结果,搜索用时 234 毫秒
141.
超声图像处理中Snake模型研究 总被引:3,自引:0,他引:3
Snake模型是一种基于高层信息的有效目标轮廓提取算法,其优点是作用过程及最后结果的目标轮廓是一条完整的曲线,从而引起广泛的关注。鉴于医学超声图像的信噪比较低,用经典的边缘提取算法无法得到较好的结果,因此人们将Snake模型进行了各种各样的改进,并且越来越多地将它运用到医学超声图像处理中来。本文对乳腺超声图像进行阈值分割、形态滤波等一系列预处理后,将改进的Snake模型对乳腺超声图像进行肿瘤的边缘提取,得到了比较好的结果。 相似文献
142.
143.
生态学数学模型参数优化估计的遗传算法 总被引:1,自引:0,他引:1
本文提出用遗传算法,对生态学中的一些数学模型参数进行优化估计,并以崔-lawson方程为例.尝试了遗传算法的效果.结果表明,该方法性能良好,可望成为生态学中各类非线性模型辨识的有效参数. 相似文献
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145.
《FEBS letters》1993,330(3):293-296
A complete cDNA encoding rabbit Uteroglobin was constructed and expressed in MDCK and Caco-2 cells. The MDCK cells secrete Uteroglobin in approximately equal amounts to the apical and the basolateral side, whereas the Caco-2 cells secrete Uteroglobin mainly to the basolateral side. Both MDCK and Caco-2 cells thus secrete Uteroglobin in a non-sorted manner. It has, however, previously been shown that Uteroglobin is secreted exclusively at the apical membrane in primary cell culture of endometrial epithelial cells [S.K. Mani et al. (1991) Endocrinology 128, 1563-1573]. This suggests that either the endometrial epithelium has an apical default pathway or recognises a sorting signal not recognised by MDCK cells and Caco-2 cells. Our data thus show that a soluble molecule can be secreted at the apical, the basolateral or both membranes depending on the cell type. 相似文献
146.
Takaki R 《Journal of biosciences》2005,30(1):87-92
Because the morphogenesis of biological systems is not fully understood, researches from various points of view are necessary.
The present author has recently made computer simulations with his colleagues to construct branching systems of human organs,
such as the lung airway and the liver blood vessels. In the simulations certain rules are assumed to govern bifurcating processes
of the systems. These rules are expressed in terms of physical and geometrical concepts, such as minimum energy consumption
and uniform filling of branches in the space of organs. Results of computer simulation are quite similar to real structures.
However, actual mechanisms of morphogenesis, i.e. effects of genes or proteins, are not considered in these studies. In this
article, the present work is discussed in relation to the concept of biological pattern formation by Meinhardt and a recent
study by Miura and Shiota on lung growth. 相似文献
147.
Knowledge of the 3D structure of glycans is a prerequisite for a complete understanding of the biological processes glycoproteins are involved in. However, due to a lack of standardised nomenclature, carbohydrate compounds are difficult to locate within the Protein Data Bank (PDB). Using an algorithm that detects carbohydrate structures only requiring element types and atom coordinates, we were able to detect 1663 entries containing a total of 5647 carbohydrate chains. The majority of chains are found to be N-glycosidically bound. Noncovalently bound ligands are also frequent, while O-glycans form a minority. About 30% of all carbohydrate containing PDB entries comprise one or several errors. The automatic assignment of carbohydrate structures in PDB entries will improve the cross-linking of glycobiology resources with genomic and proteomic data collections, which will be an important issue of the upcoming glycomics projects. By aiding in detection of erroneous annotations and structures, the algorithm might also help to increase database quality. 相似文献
148.
目的:生物标志物是标识系统、器官、组织等改变或可能发生改变的生化指标,具有非常广泛的临床应用。本文希望从高通量数据出发,提出一种新的研究复杂疾病标志物的方法。方法:以"组学"数据为研究对象,利用乒乓算法构建lnc RNA-mRNA交互网络,通过随机游走算法计算选出复杂疾病的生物标志物,并将其与t检验结果比较。结果:将本文方法运用于食管癌标志物的识别,得出与食管癌发生和发展过程相关的14个lnc RNA(CCAT1、MEG3、Snhg1、MALAT1、HOTAIR、UCA1、PVT1、CASC9、LOC100130476、TUG1、BC200、POU6F2-AS2、TP73-AS1和ZEB1-AS1)和12个mRNA(SPARC、CMTM7、Sph K1、NANOG、LOXL2、HMGCS2、FZD7、PTOV1、CADM1、CTHRC1、MGMT和RECK)。对比显示,识别出t检验未识别出的4个lnc RNA(BC200、POU6F2-AS2、TP73-AS1和ZEB1-AS1)和3个mRNA(CADM1、Sph K1和RECK)。结论:该方法能够更有效的预测复杂疾病相关的标志物。 相似文献
149.
Polygenic risk for schizophrenia and neurocognitive performance in patients with schizophrenia
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S.‐H. Wang P.‐C. Hsiao L.‐L. Yeh C.‐M. Liu C.‐C. Liu T.‐J. Hwang M. H. Hsieh Y.‐L. Chien Y.‐T. Lin S. D. Chandler S. V. Faraone N. Laird B. Neale S. A. McCarroll S. J. Glatt M. T. Tsuang H.‐G. Hwu W. J. Chen 《Genes, Brain & Behavior》2018,17(1):49-55
Both neurocognitive deficits and schizophrenia are highly heritable. Genetic overlap between neurocognitive deficits and schizophrenia has been observed in both the general population and in the clinical samples. This study aimed to examine if the polygenic architecture of susceptibility to schizophrenia modified neurocognitive performance in schizophrenia patients. Schizophrenia polygenic risk scores (PRSs) were first derived from the Psychiatric Genomics Consortium (PGC) on schizophrenia, and then the scores were calculated in our independent sample of 1130 schizophrenia trios, who had PsychChip data and were part of the Schizophrenia Families from Taiwan project. Pseudocontrols generated from the nontransmitted parental alleles of the parents in these trios were compared with alleles in schizophrenia patients in assessing the replicability of PGC‐derived susceptibility variants. Schizophrenia PRS at the P‐value threshold (PT) of 0.1 explained 0.2% in the variance of disease status in this Han‐Taiwanese samples, and the score itself had a P‐value 0.05 for the association test with the disorder. Each patient underwent neurocognitive evaluation on sustained attention using the continuous performance test and executive function using the Wisconsin Card Sorting Test. We applied a structural equation model to construct the neurocognitive latent variable estimated from multiple measured indices in these 2 tests, and then tested the association between the PRS and the neurocognitive latent variable. Higher schizophrenia PRS generated at the PT of 0.1 was significantly associated with poorer neurocognitive performance with explained variance 0.5%. Our findings indicated that schizophrenia susceptibility variants modify the neurocognitive performance in schizophrenia patients. 相似文献
150.