首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   764篇
  免费   47篇
  国内免费   1篇
  2023年   3篇
  2022年   5篇
  2021年   20篇
  2020年   18篇
  2019年   19篇
  2018年   26篇
  2017年   16篇
  2016年   29篇
  2015年   49篇
  2014年   50篇
  2013年   61篇
  2012年   80篇
  2011年   83篇
  2010年   43篇
  2009年   38篇
  2008年   59篇
  2007年   40篇
  2006年   34篇
  2005年   27篇
  2004年   27篇
  2003年   11篇
  2002年   26篇
  2001年   12篇
  2000年   15篇
  1999年   5篇
  1998年   4篇
  1997年   2篇
  1996年   1篇
  1995年   1篇
  1994年   2篇
  1992年   4篇
  1988年   2篇
排序方式: 共有812条查询结果,搜索用时 19 毫秒
71.
Li metal, which has a high theoretical specific capacity and low redox potential, is considered to the most promising anode material for next‐generation Li ion‐based batteries. However, it also exhibits a disadvantageous solid electrolyte interphase (SEI) layer problem that needs to be resolved. Herein, an advanced separator composed of reduced graphene oxide fiber attached to aramid paper (rGOF‐A) is introduced. When rGOF‐A is applied, F? anions, generated from the decomposition of the LiPF6 electrolyte during the SEI layer formation process form semi‐ionic C? F bonds along the surface of rGOF. As Li+ ions are plated, the “F‐doped” rGO surface induces the formation of LiF, which is known as a component of a chemically stable SEI, therefore it helps the Li metal anode to operate stably at a high current of 20 mA cm?2 with a high capacity of 20 mAh cm?2. The proposed rGOF‐A separator successfully achieves a stable SEI layer that could resolve the interfacial issues of the Li metal anode.  相似文献   
72.
Sibling-based tests of linkage and association for quantitative traits.   总被引:6,自引:0,他引:6  
The transmission/disequilibrium test (TDT) developed by Spielman et al. can be a powerful family-based test of linkage and, in some cases, a test of association as well as linkage. It has recently been extended in several ways; these include allowance for implementation with quantitative traits, allowance for multiple alleles, and, in the case of dichotomous traits, allowance for testing in the absence of parental data. In this article, these three extensions are combined, and two procedures are developed that offer valid joint tests of linkage and (in the case of certain sibling configurations) association with quantitative traits, with use of data from siblings only, and that can accommodate biallelic or multiallelic loci. The first procedure uses a mixed-effects (i.e., random and fixed effects) analysis of variance in which sibship is the random factor, marker genotype is the fixed factor, and the continuous phenotype is the dependent variable. Covariates can easily be accommodated, and the procedure can be implemented in commonly available statistical software. The second procedure is a permutation-based procedure. Selected power studies are conducted to illustrate the relative power of each test under a variety of circumstances.  相似文献   
73.
74.
The Saccharomyces cerevisiae gene RHC21 is a homologue of the fission yeast rad21 +gene, which affects the sensitivity of cells to γ-irradiation and is essential for cell growth in S. pombe. Disruption of the RHC21 gene showed that it is also essential in S. cerevisiae. To examine its function in cell growth further, we have isolated temperature-sensitive mutants for the RHC21 gene and characterized one of them, termed rhc21-sk16. When this mutant was incubated at 36° C, the percentage of large-budded cells was increased. Most of the large-budded cells had aberrant nuclear structures, such as unequally extended nuclear DNA with incompletely elongated spindles across the mother-daughter neck or only in a mother cell. Furthermore, a circular minichromosome is more unstable in the mutant than in the wild-type, even at 25° C. Flow cytometry showed that the bulk of DNA replication takes place normally at the restrictive temperature in the mutant. These results indicated that the RHC21 gene is required for proper segregation of the chromosomes. In addition, we found that the mutant is sensitive not only to UV radiation and γ-rays but also to the antimicrotubule agent nocodazole at 25° C. This suggests that the RHC21 gene is involved in the microtubule function. We discuss how the RHC21 gene product may be involved in chromosome segregation and microtubule function. Received: 10 March 1997 / Accepted: 1 September 1997  相似文献   
75.
The Saccharomyces cerevisiae gene RHC21 is a homologue of the fission yeast rad21 +gene, which affects the sensitivity of cells to γ-irradiation and is essential for cell growth in S. pombe. Disruption of the RHC21 gene showed that it is also essential in S. cerevisiae. To examine its function in cell growth further, we have isolated temperature-sensitive mutants for the RHC21 gene and characterized one of them, termed rhc21-sk16. When this mutant was incubated at 36°?C, the percentage of large-budded cells was increased. Most of the large-budded cells had aberrant nuclear structures, such as unequally extended nuclear DNA with incompletely elongated spindles across the mother-daughter neck or only in a mother cell. Furthermore, a circular minichromosome is more unstable in the mutant than in the wild-type, even at 25°?C. Flow cytometry showed that the bulk of DNA replication takes place normally at the restrictive temperature in the mutant. These results indicated that the RHC21 gene is required for proper segregation of the chromosomes. In addition, we found that the mutant is sensitive not only to UV radiation and γ-rays but also to the antimicrotubule agent nocodazole at 25°?C. This suggests that the RHC21 gene is involved in the microtubule function. We discuss how the RHC21 gene product may be involved in chromosome segregation and microtubule function.  相似文献   
76.
77.
The present study explores the ethnic and religious identities of 21 multicultural young adults with a Japanese mother and a Korean father, all residing in South Korea where the “myth” of a mono-ethnic nation still lingers. In the study, one is considered multicultural provided they are born to both one foreign-born parent and one Korean-born parent. All interviewees are members of the Family Federation for World Peace Unification religion established in South Korea in the 1950s. Interviews with these young adults showed (a) that there was an intersectionality between their ethnic identity and religious identity; (b) that the influence of the interaction between the Church and the mother on the ethnic and religious identities of the interviewees was substantial; and (c) that they distinguished themselves from other multicultural individuals and even from non-multicultural individuals concerning their socio-economic background and transcending religious mission.  相似文献   
78.
79.
Osteosarcoma is the most common type of malignant bone tumors. Insulin Growth Factor 1 receptor (IGFR1) has been known as a prognostic factor for metastasis of osteosarcoma. ABC subfamily G member2 (ABCG2) is related to resistance to anti-cancer drug, and CD44 has a role in tumor growth and metastasis. The purpose of this study is to investigate the relationship among expression patterns of IGF1R, ABCG2, and CD44 in osteosarcoma. The expression levels of IGF1R, ABCG2, and CD44 proteins were determined in tissue arrays containing osteosarcoma tissues from 59 osteosarcoma patients. The expression pattern of IGF1R was highly correlated with the expression pattern of ABCG2 (r?=?0.88) in overall osteosarcoma patients. According to pathological types, the expression pattern of IGF1R showed the higher correlation with ABGC2 (r?=?0.90) and CD44 (r?=?0.61) in osteoblatic type than in chondroblastic type. According to gender with pathologic type, the correlation between the expression patterns of IGF1R and CD44 was higher in male with osteoblatic type than in female with osteoblatic type. Among different age groups, the 1–10 years age group showed higher correlation in IGF1R versus CD44 (r?=?0.90) and ABCG2 versus CD44 (0.80) than in other age groups. These results showed that the expression of IGF1R appears to be highly correlated with the expression of ABCG2 in osteosarcoma and with the expression of CD44 in osteosarcoma patients under age of 10, which suggests that ABCG2 and CD44 can be used as prognostic factors with IGF1R for specific prognosis and efficient treatment of osteosarcoma.  相似文献   
80.
Excessive production of reactive oxygen species (ROS), along with dysfunction of the antioxidant defense system, such as that involving superoxide dismutase (SOD), may play a major role in neuronal death following status epilepticus (SE). Neurosteroids, which are allosteric modulators of the GABAA receptor in cerebral metabolism, have been suggested as being neuroprotective in various animal models; however, their effect to preventing ROS has not been examined. Herein, we investigate the neuroprotective role of allopregnanolone, the prototypical neurosteroid in the brain, in relation to the ROS-mediated neuronal injury. Adult male C57BL/6 mice were subjected to SE and treated with allopregnanolone. Hippocampal cell death was assessed by the terminal deoxynucleotidyl transferase dUTP nick end labeling assay, and ROS production was investigated by in situ detection of oxidized hydroethidine. SOD2 expression was analyzed by both western blot and immunofluorescent staining in the hippocampal subfields. In mice treated with allopregnanolone after SE, hippocampal cell death, DNA fragmentation, oxidative DNA damage, and ROS production were reduced significantly compared to mice subjected to vehicle treatment after SE. Hippocampal SOD2 expression was significantly increased by allopregnanolone. These finding suggest that allopregnanolone plays a neuroprotective role, with not only anticonvulsant but also antioxidant effects, by increasing SOD2 in pilocarpine-induced SE model.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号