全文获取类型
收费全文 | 1346篇 |
免费 | 85篇 |
国内免费 | 1篇 |
专业分类
1432篇 |
出版年
2024年 | 3篇 |
2023年 | 9篇 |
2022年 | 13篇 |
2021年 | 24篇 |
2020年 | 15篇 |
2019年 | 20篇 |
2018年 | 23篇 |
2017年 | 19篇 |
2016年 | 44篇 |
2015年 | 85篇 |
2014年 | 85篇 |
2013年 | 103篇 |
2012年 | 122篇 |
2011年 | 116篇 |
2010年 | 77篇 |
2009年 | 60篇 |
2008年 | 81篇 |
2007年 | 83篇 |
2006年 | 78篇 |
2005年 | 76篇 |
2004年 | 69篇 |
2003年 | 60篇 |
2002年 | 50篇 |
2001年 | 18篇 |
2000年 | 14篇 |
1999年 | 11篇 |
1998年 | 14篇 |
1997年 | 8篇 |
1996年 | 4篇 |
1995年 | 4篇 |
1994年 | 8篇 |
1993年 | 2篇 |
1990年 | 3篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1972年 | 1篇 |
1968年 | 1篇 |
1967年 | 2篇 |
1965年 | 2篇 |
1962年 | 1篇 |
1961年 | 1篇 |
1960年 | 1篇 |
1959年 | 1篇 |
1952年 | 2篇 |
1951年 | 1篇 |
1950年 | 1篇 |
排序方式: 共有1432条查询结果,搜索用时 0 毫秒
101.
The contemporary distribution and genetic structure of a freshwater fish provide insight into its historical geodispersal and geographical isolation following Quaternary climate changes. The short ninespine stickleback, Pungitius kaibarae, is a small gasterosteid fish occurring in freshwater systems on the Korean Peninsula and in southeast Russia. On the Korean Peninsula, P. kaibarae populations are distributed in three geographically separated regions: the NE (northeast coast), SE (southeast coast), and a limited area in the ND (Nakdong River). In this study, we used mitochondrial loci and microsatellites to investigate the evolutionary history of P. kaibarae populations by assessing their pattern of genetic structure. Our analyses revealed a marked level of divergence among three regional populations, suggesting a long history of isolation following colonization, although ND individuals showed relatively higher genetic affinity to populations from SE than those from NE. The populations from NE showed a great degree of interpopulation differentiation, whereas populations from SE exhibited only weak genetic structuring. Upon robust phylogenetic analysis, P. kaibarae formed a monophyletic group with Russian P. sinensis and P. tymensis with strong node confidence values, indicating that P. kaibarae populations on the Korean Peninsula originated from the southward migration of its ancestral lineage around the middle Pleistocene. 相似文献
102.
Eun Young Hwang Mi Suk Jeong Eun-Kyeong Park Jae Ho Kim Se Bok Jang 《Biochemical and biophysical research communications》2014
Periostin appears to be a unique extracellular protein secreted by fibroblasts that is upregulated following injury to the heart or changes in the environment. Periostin has the ability to associate with other critical extracellular matrix (ECM) regulators such as TGF-β, tenascin, and fibronectin, and is a critical regulator of fibrosis that functions by altering the deposition and attachment of collagen. Periostin is known to be highly expressed in carcinoma cells, but not in normal breast tissues. The protein has a structural similarity to insect fasciclin-1 (Fas 1) and can be induced by transforming growth factor-β (TGF-β) and bone morphogenetic protein (BMP)-2. To investigate the molecular interaction of periostin and bone morphogenetic protein, we modeled these three-dimensional structures and their binding sites. We demonstrated direct interaction between periostin and BMP1/2 in vitro using several biochemical and biophysical assays. We found that the structures of the first, second, and fourth Fas1 domains in periostin are similar to that of the fourth Fas 1 domain of TGFBIp. However, the structure of the third Fas 1 domain in periostin is different from those of the first, second, and fourth Fas1 domains, while it is similar to the NMR structure of Fasciclin-like protein from Rhodobacter sphaeroides. These results will useful in further functional analysis of the interaction of periostin and bone morphogenetic protein. 相似文献
103.
Apoptosis can be induced by an extrinsic pathway involving the ligand-mediated activation of death receptors such as tumor necrosis factor receptor-1 (TNFR-1). TNFR-1-associated death domain (TRADD) protein is an adapter molecule that bridges the interaction between TNFR-1 and receptor-interacting serine/threonine-protein kinase 1 (RIP1). However, the molecular mechanism of the complex formation of these proteins has not yet been identified. Here, the binding among TNFR-1, TRADD, and RIP1 was identified using a GST pull-down assay and Biacore biosensor experiment. This study showed that structural characterization and formation of the death-signaling complex could be predicted using TNFR-1, TRADD, and RIP1. In addition, we found that the structure-based mutations of TNFR-1 (P367A and P368A), TRADD (F266A), and RIP1 (M637A and R638A) disrupted formation of the death domain (DD) complex and prevented stable interactions among those DDs. 相似文献
104.
Hong Zhu Hee Yun Suk Raymond Y. L. Yu Deborah Brancho Opeyemi Olabisi Teddy T. C. Yang XiaoYong Yang Jialin Zhang Mustapha Moussaif Jorge L. Durand Linda A. Jelicks Ja-Young Kim Philipp E. Scherer Philippe G. Frank Michael P. Lisanti John W. Calvert Mark R. Duranski David J. Lefer Elaine Huston George S. Baillie Miles D. Houslay Jeffrey D. Molkentin Jianping Jin Chi-Wing Chow 《Molecular and cellular biology》2010,30(18):4379-4390
105.
Hye Jin Chung Dong Woon Lee Hee Suk Yoon Sang Myeong Lee Chung Gyoo Park Ho Yul Choo 《Journal of Asia》2010,13(4):277-282
Out of some isolated Heterorhabditis bacteriophora from Korea, ecological study on two isolates which had different geographical features was investigated. That is, effects of temperature and dose on the pathogenicity and reproduction of two Korean isolates of H. bacteriophora were investigated using Galleria mellonella larvae in the laboratory. The median lethal dose (LD50) decreased with increasing temperature, but increased at 35 °C. The optimal temperatures for infection were 30 °C for H. bacteriophora Jeju strain and 24 °C for H. bacteriophora Hamyang strain. The median lethal time, LT50 of H. bacteriophora Hamyang strain was recorded at 13 °C to 35 °C and that of H. bacteriophora Jeju strain was recorded at 18 °C to 30 °C. The number of established nematodes in G. mellonella larvae was significantly different depending on temperature and dose. When G. mellonella larvae were exposed to 300 infective juveniles (IJs), mortality of G. mellonella gradually increased with exposure time with H. bacteriophora Jeju strain but not with H. bacteriophora Hamyang strain. 87.5% mortality of G. mellonella was recorded by H. bacteriophora Hamyang strain after 1440 min whereas 100% mortality was recorded by H. bacteriophora Jeju strain after 4320 min. The time from infection to the first emergence of nematodes decreased with increasing temperature. Duration of emergence of the two strains in the White traps also decreased with increasing temperature. The highest progeny numbers of H. bacteriophora Jeju strain were 264,602 while those of H. bacteriophora Hamyang strain were 275,744 at the rate of 160 IJs at 24 °C. 相似文献
106.
Park IS Park JU Seo MJ Kim MJ Lee HH Kim SR Kang BW Choi YH Joo WH Jeong YK 《Journal of microbiology (Seoul, Korea)》2010,48(6):836-841
A fibrinolytic enzyme of the mushroom, Schizophyllum commune was purified with chromatographic methods, including a DEAE-Sephadex A-50 ion-exchange column and gel filtrations with Sephadex
G-75 and Sephadex G-50 columns. The analysis of fibrin-zymography and SDS-PAGE showed that the enzyme was a monomeric subunit
that was estimated to be approximately 17 kDa in size. The fibrinolytic activity of the enzyme in plasminogen-rich and plasminogen-free
fibrin plates was 1.25 and 0.44 U/ml, respectively. The N-terminal amino acid sequence of the purified enzyme was identified
as HYNIXNSWSSFID, which was highly distinguished from known fibrinolytic enzymes. The relative activity of the purified enzyme
with an addition of 5 mM EDTA, Phosphoramidon, and Bestatin was about 76, 64, and 52%, respectively, indicating that it is
a metalloprotease. The optimum temperature for the purified enzyme was approximately 45°C, and over 87% of the enzymatic activity
was maintained as a stable state in a pH range from 4.0 to 6.0. Therefore, our results suggest that the potential thrombolytic
agent from S. commune is a unique type of fibrinolytic enzyme. 相似文献
107.
Jin Hyoung Kim Young Suk Yu Kyu-Won Kim Jeong Hun Kim 《Histochemistry and cell biology》2010,134(3):277-284
This study was to investigate the effect of the absence of ganglion cells on the development of human retinal vasculature.
Anencephaly (AnC) and age-matched control eyes derived from each three spontaneously aborted fetus (ranging from 15 to 20 weeks
gestation) were subjected to immunofluorescence staining for HIF-1α, Thy-1, glial fibrillary acidic protein (GFAP) and platelet/endothelial cell adhesion molecule (PECAM) and apoptosis assay. In developing
mouse retina, Western blotting for hypoxia-inducible factor-1α (HIF-1α) and vascular endothelial growth factor (VEGF) was
performed. Under hypoxic condition (O2 < 1%), cellular proliferation and VEGF mRNA expression in astrocytes were measured. Apoptotic cells in AnC retina were primarily
localized in the ganglion cell layer (GCL), whereas apoptotic cells in normal retina were distributed in the retinoblastic
layer. With increase of apoptotic cells in GCL of AnC retina, HIF-1α expression were severely distinguished in avascular retina
and GFAP expression in junctional area between avascular and vascular retina was much reduced, accompanied by decrease of
PECAM expression compared to normal retina. In developing mouse retina, HIF-1α and VEGF expression were high in hypoxic retina
of early stage with incomplete vascular development and then progressively decreased with regression to arborous pattern of
matured vascular networks. In hypoxic condition, a significant increase in cellular proliferation and VEGF mRNA expression
was observed in astrocytes. Therefore, our results suggest that vascular attenuation in AnC retina could be closely related
to the absence of ganglion cells as the metabolic demander to induce retinal vascular development. 相似文献
108.
Germ cells and somatic cells have the identical genome. However, unlike the mortal fate of somatic cells, germ cells have the unique ability to differentiate into gametes that retain totipotency and produce an entire organism upon fertilization. The processes by which germ cells differentiate into gametes, and those by which gametes become embryos, involve dramatic cellular differentiation accompanied by drastic changes in gene expression, which are tightly regulated by genetic circuitries as well as epigenetic mechanisms. Epigenetic regulation refers to heritable changes in gene expression that are not due to changes in primary DNA sequence. The past decade has witnessed an ever-increasing understanding of epigenetic regulation in many different cell types/tissues during embryonic development and adult homeostasis. In this review, we focus on recent discoveries of epigenetic regulation of germ cell differentiation in various metazoan model organisms, including worms, flies, and mammals. 相似文献
109.
110.