全文获取类型
收费全文 | 97篇 |
免费 | 1篇 |
国内免费 | 3篇 |
专业分类
系统科学 | 1篇 |
丛书文集 | 1篇 |
理论与方法论 | 1篇 |
现状及发展 | 26篇 |
研究方法 | 6篇 |
综合类 | 65篇 |
自然研究 | 1篇 |
出版年
2021年 | 1篇 |
2020年 | 1篇 |
2019年 | 1篇 |
2018年 | 2篇 |
2016年 | 1篇 |
2015年 | 1篇 |
2013年 | 3篇 |
2012年 | 3篇 |
2011年 | 5篇 |
2010年 | 4篇 |
2009年 | 2篇 |
2008年 | 5篇 |
2007年 | 2篇 |
2006年 | 6篇 |
2005年 | 2篇 |
2004年 | 6篇 |
2003年 | 2篇 |
2002年 | 4篇 |
2001年 | 4篇 |
2000年 | 4篇 |
1998年 | 5篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 3篇 |
1977年 | 2篇 |
1976年 | 3篇 |
1974年 | 2篇 |
1972年 | 1篇 |
1971年 | 3篇 |
1970年 | 1篇 |
1969年 | 2篇 |
排序方式: 共有101条查询结果,搜索用时 15 毫秒
1.
为贯彻水电部《电力系统谐波管理暂行规定》文件,适应电网谐波检测管理的需要,研制了本装置。它在微处理机的基础上实现了对电网谐波的自动检测:能测量基波至19次谐波的电压、电流、相位、有功和无功功率,以及电压和电流的总畸变率。本文简述其工作原理、硬件框图、程序流程图、提高测量准确度的措施、测试结果等。 相似文献
2.
The implication of corporate bankruptcy prediction is important to financial institutions when making lending decisions. In related studies, many bankruptcy prediction models have been developed based on some machine‐learning techniques. This paper presents a meta‐learning framework, which is composed of two‐level classifiers for bankruptcy prediction. The first‐level multiple classifiers perform the data reduction task by filtering out unrepresentative training data. Then, the outputs of the first‐level classifiers are utilized to create the second‐level single (meta) classifier. The experiments are based on five related datasets and the results show that the proposed meta‐learning framework provides higher prediction accuracy rates and lower type I/II errors when compared with the stacked generalization classifier and other three widely developed baselines, such as neural networks, decision trees, and logistic regression. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
3.
Analysis of chromosomes from cells treated with adriamycin during G2 and S phases showed a high frequency of isochromatid-type of breaks, in addition to the expected chromatid breaks. These are interpreted as independent breaks on sister chromatids because of preferential effects of the drug in specific chromosome regions. The break points are likely to be different, but morphologically such breaks would be indistinguishable from isochromatid or chromosome breaks. 相似文献
4.
Drosophila TCTP is essential for growth and proliferation through regulation of dRheb GTPase 总被引:2,自引:0,他引:2
Cellular growth and proliferation are coordinated during organogenesis. Misregulation of these processes leads to pathological conditions such as cancer. Tuberous sclerosis (TSC) is a benign tumour syndrome caused by mutations in either TSC1 or TSC2 tumour suppressor genes. Studies in Drosophila and other organisms have identified TSC signalling as a conserved pathway for growth control. Activation of the TSC pathway is mediated by Rheb (Ras homologue enriched in brain), a Ras superfamily GTPase. Rheb is a direct target of TSC2 and is negatively regulated by its GTPase-activating protein activity. However, molecules required for positive regulation of Rheb have not been identified. Here we show that a conserved protein, translationally controlled tumour protein (TCTP), is an essential new component of the TSC-Rheb pathway. Reducing Drosophila TCTP (dTCTP) levels reduces cell size, cell number and organ size, which mimics Drosophila Rheb (dRheb) mutant phenotypes. dTCTP is genetically epistatic to Tsc1 and dRheb, but acts upstream of dS6k, a downstream target of dRheb. dTCTP directly associates with dRheb and displays guanine nucleotide exchange activity with it in vivo and in vitro. Human TCTP (hTCTP) shows similar biochemical properties compared to dTCTP and can rescue dTCTP mutant phenotypes, suggesting that the function of TCTP in the TSC pathway is evolutionarily conserved. Our studies identify TCTP as a direct regulator of Rheb and a potential therapeutic target for TSC disease. 相似文献
5.
创新是企业成长的动力,而设计可以视为企业一项整合资源,也是产品开发成功的关键因素。但在企业实际产品研发过程中,设计要如何运作,才能达到企业创新的目标,是值得探讨的议题。在过去的研究中发现企业在产品设计方面,的确有一些具体的作法。但是实证企业在创新策略与设计策略乃至具体呈现设计特色之关联模型的研究却非常有限。本研究综合过去有关创新策略、设计策略以及设计特色之文献,针对新产品研发部门主管进行问卷调查。再以结构方程模式检验理论模式和观察数据的适配度。研究结果发现:创新策略、设计策略以及设计特色之关联理论模式和观察数据适配。企业之创新策略会影响产品设计特色,同时企业之创新策略会透过设计策略而影响产品设计特色,其中设计策略对设计特色而言,既是自变项又是中介变项。企业经营者所面临的挑战,往往是如何更快速地推出迎合消费市场需求之新产品,并且有效获利。本研究为首次针对这些创新设计策略变项所进行的实证研究,后续将再针对产品创新设计的议题进一步深入研讨。 相似文献
6.
Qingdi Quentin Li Iawen Hsu Thomas Sanford Reema Railkar Navin Balaji Carole Sourbier Cathy Vocke K. C. Balaji Piyush K. Agarwal 《Cellular and molecular life sciences : CMLS》2018,75(5):939-963
The protein kinase D (PKD) family of proteins are important regulators of tumor growth, development, and progression. CRT0066101, an inhibitor of PKD, has antitumor activity in multiple types of carcinomas. However, the effect and mechanism of CRT0066101 in bladder cancer are not understood. In the present study, we show that CRT0066101 suppressed the proliferation and migration of four bladder cancer cell lines in vitro. We also demonstrate that CRT0066101 blocked tumor growth in a mouse flank xenograft model of bladder cancer. To further assess the role of PKD in bladder carcinoma, we examined the three PKD isoforms and found that PKD2 was highly expressed in eight bladder cancer cell lines and in urothelial carcinoma tissues from the TCGA database, and that short hairpin RNA (shRNA)-mediated knockdown of PKD2 dramatically reduced bladder cancer growth and invasion in vitro and in vivo, suggesting that the effect of the compound in bladder cancer is mediated through inhibition of PKD2. This notion was corroborated by demonstrating that the levels of phospho-PKD2 were markedly decreased in CRT0066101-treated bladder tumor explants. Furthermore, our cell cycle analysis by flow cytometry revealed that CRT0066101 treatment or PKD2 silencing arrested bladder cancer cells at the G2/M phase, the arrest being accompanied by decreases in the levels of cyclin B1, CDK1 and phospho-CDK1 (Thr161) and increases in the levels of p27Kip1 and phospho-CDK1 (Thr14/Tyr15). Moreover, CRT0066101 downregulated the expression of Cdc25C, which dephosphorylates/activates CDK1, but enhanced the activity of the checkpoint kinase Chk1, which inhibits CDK1 by phosphorylating/inactivating Cdc25C. Finally, CRT0066101 was found to elevate the levels of Myt1, Wee1, phospho-Cdc25C (Ser216), Gadd45α, and 14-3-3 proteins, all of which reduce the CDK1-cyclin B1 complex activity. These novel findings suggest that CRT0066101 suppresses bladder cancer growth by inhibiting PKD2 through induction of G2/M cell cycle arrest, leading to the blockade of cell cycle progression. 相似文献
7.
Prevotella bivia is associated with pelvic inflammatory disease. A 77-year-old man developed a rapidly growing chest wall abscess due to P. bivia within days. He underwent surgical resection of the infected area; his postoperative course was uneventful. This is the first case of chest wall abscess due to P. bivia infection. Its correct diagnosis cannot be underestimated because fulminant infections can occur in aged or immunocompromised patients if treated incorrectly. Prompt, appropriate surgical management, and antibiotic therapy affect treatment outcome. 相似文献
8.
A new A4 amyloid mRNA contains a domain homologous to serine proteinase inhibitors 总被引:98,自引:0,他引:98
P Ponte P Gonzalez-DeWhitt J Schilling J Miller D Hsu B Greenberg K Davis W Wallace I Lieberburg F Fuller 《Nature》1988,331(6156):525-527
The amyloid proteins isolated from neuritic plaques and the cerebrovasculature of Alzheimer's disease are self-aggregating moieties termed A4 protein and beta-protein, respectively. A putative A4 amyloid precursor (herein termed A4(695] has been characterized by analysis of a human brain complementary DNA. We report here the sequence of a closely related amyloid cDNA, A4(751), distinguished from A4(695) by the presence of a 168 base-pair (bp) sequence which adds 57 amino acids to, and removes one residue from, the predicted A4(695) protein. The peptide predicted from this insert is very similar to the Kunitz family of serine proteinase inhibitors. The two A4-specific messenger RNAs are differentially expressed: in a limited survey, A4(751) mRNA appears to be ubiquitous, whereas A4(695) mRNA has a restricted pattern of expression which includes cells from neuronal tissue. These data may have significant implications for understanding amyloid deposition in Alzheimer's disease. 相似文献
9.
Site specific integrative recombination of bacteriophage lambda involves unequal partners. The minimal phage att site is composed of approximately 240-base pairs and four distinct binding sites for Int protein, at least three of which are crucial for function. This 'donor site' recombines efficiently with a smaller 'recipient site' that lacks the extensive interactions with Int protein. 相似文献
10.
Distribution of repetitious DNA in human chromosomes 总被引:5,自引:0,他引:5