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51.
Understanding the role of geography and ecology in species divergence is central to the study of evolutionary diversification. We used climatic, geographic, and biological data from nine wild Andean tomato species to describe each species' ecological niche and to evaluate the likely ecological and geographical modes of speciation in this clade. Using data from >1000 wild accessions and publicly available data derived from geographic information systems for various environmental variables, we found most species pairs were significantly differentiated for one or more environmental variables. By comparing species' predicted niches generated by species distribution modeling (SDM), we found significant niche differentiation among three of four sister-species pairs, suggesting ecological divergence is consistently associated with recent divergence. In comparison, based on age-range correlation (ARC) analysis, there was no evidence for a predominant geographical (allopatric vs. sympatric) context for speciation in this group. Overall, our results suggest an important role for environmentally mediated differentiation, rather than simply geographical isolation, in species divergence. 相似文献
52.
Nagamine T Nakazato K Suzuki K Kusakabe T Sakai T Oikawa M Satoh T Kamiya T Arakawa K 《Biological trace element research》2007,117(1-3):115-126
This study undertook the analysis of tissue cadmium (Cd) distribution using in-air micro-particle-induced X-ray emission (PIXE)
and the examination of the involvement of metal ions in parenteral Cd toxicity. A mouse was injected intraperitoneally with
3 mg/kg body weight of CdCl2 thrice weekly. After 27 wk, the liver and kidney were excised and fixed in 10% formalin solution for 4 h and then embedded
in paraffin. Thin paraffin sections were used to analyze trace elements with in-air micro-PIXE and to examine metallothionein
protein and histological changes. Cd distribution was determined by micro-PIXE in the liver and renal cortex of the Cd-exposed
mouse, and the net Cd count was higher in the liver than in the renal cortex. The net iron (Fe) count was higher in the liver
of the Cd-exposed mouse compared to the control, and an opposite tendency was observed in the renal cortex. Wide cellular
Cd distribution was demonstrated in the liver and renal cortex of the chronic Cd-exposed mouse compared to the control. Metallothionein
staining was increased by chronic exposure to Cd both in the liver and kidney, and nephrotoxicity was more apparent than hepatotoxicity.
The modification of tissue Fe and calcium distribution by an intraperitoneal injection of Cd might be involved in Cd-induced
toxicity. 相似文献
53.
Under laboratory conditions, spores of ectomycorrhizal fungi usually germinate very poorly or not at all. In a previous study,
we showed that spores of the ectomycorrhizal fungus Suillus bovinus germinated through the combination of activated charcoal treatment of media and co-culture with seedlings of Pinus densiflora, which suggested that some substances contained in root exudates induced the germination. Among the compounds reported from
root exudates, flavonoids have been elucidated to play various and substantial roles in plant–microbe interactions; we therefore
investigated the effects of flavonoids on basidiospore germination of S. bovinus by the diffusion gradient assay on water agar plates pretreated with charcoal powder. Seven out of the 11 flavonoids tested,
hesperidin, morin, rutin, quercitrin, naringenin, genistein, and chrysin, had greater effects than controls, whereas flavone,
biochanin A, luteolin, and quercetin showed no positive effects. The effective concentration presumably corresponded to several
micromolar levels, which was equivalent to those effective for pollen development, nod gene induction, and spore germination of F. solani f. sp. pisi and AM fungi. The results suggest that flavonoids play a role as signaling molecules in symbiotic relationships between woody
plants and ectomycorrhizal fungi. 相似文献
54.
Hirokawa YS Takagi A Uchida K Kozuka Y Yoneda M Watanabe M Shiraishi T 《Cellular & molecular biology letters》2007,12(3):370-377
In this paper, we describe the isolation and characterization of two PC3 subclones. One subclone, mr, showed an epithelial
phenotype, the other, M1, showed a sarcomatous morphology. Transplanted into nude mice, mr developed tumors at a dramatically
faster rate than M1. Comparing the two subclones, differentially expressed genes were identified, including E-cadherin, IL-8
and STAG1/PMEPA1. These genes were expressed at higher levels in mr than in M1. 相似文献
55.
56.
Horie M Kato H Endoh S Fujita K Nishio K Komaba LK Fukui H Nakamura A Miyauchi A Nakazato T Kinugasa S Yoshida Y Hagihara Y Morimoto Y Iwahashi H 《Metallomics : integrated biometal science》2011,3(11):1244-1252
Platinum nanoparticles have industrial application, for example in catalysis, and are used in consumer products such as cosmetics and supplements. Therefore, among the many nanoparticles, platinum is one of the more accessible nanoparticles for consumers. Most platinum nanoparticles that are used in cosmetics and supplements which have an anti-oxidant activity are modified particles. However, the cellular influences of pristine platinum nanoparticles are still unclear, although it has been reported that platinum nanoparticles induce oxidative stress. In this study, we investigated the cellular influences induced by pure pristine platinum nanoparticles. Platinum nanoparticles of 100% purity were dispersed in a cell culture medium and stable medium dispersion was obtained. The platinum nanoparticle medium dispersion was applied to two kinds of cultured cells, A549 and HaCaT cells, and the cellular influences were examined. Cell viability (MTT assay), cell proliferation (clonogenic assay), apoptosis induction (caspase-3 activity), intracellular ROS level (DCFH assay), and lipid peroxidation level (DPPP assay) were measured as markers of cellular influences. Transmission electron microscope observation showed cellular uptake of platinum nanoparticles. However, the platinum nanoparticles did not drive any markers. It is known that some metal oxide nanoparticles such as NiO and CuO show severe cytotoxicity via metal ion release. Compared with these toxic nanoparticles, the platinum nanoparticles used in this study did not release platinum ions into the culture media. These results suggest that the physically and chemically inactive cellular influences of platinum nanoparticles are small. 相似文献
57.
The docking protein FRS2alpha is an essential component of multiple fibroblast growth factor responses during early mouse development 下载免费PDF全文
Gotoh N Manova K Tanaka S Murohashi M Hadari Y Lee A Hamada Y Hiroe T Ito M Kurihara T Nakazato H Shibuya M Lax I Lacy E Schlessinger J 《Molecular and cellular biology》2005,25(10):4105-4116
The docking protein FRS2alpha is a major mediator of fibroblast growth factor (FGF) signaling. However, the physiological role of FRS2alpha in vivo remains unknown. In this report, we show that Frs2alpha-null mouse embryos have a defect in anterior-posterior (A-P) axis formation and are developmentally retarded, resulting in embryonic lethality by embryonic day 8. We demonstrate that FRS2alpha is essential for the maintenance of self-renewing trophoblast stem (TS) cells in response to FGF4 in the extraembryonic ectoderm (ExE) that gives rise to tissues of the placenta. By analyzing chimeric embryos, we found that FRS2alpha also plays a role in cell movement through the primitive streak during gastrulation. In addition, experiments are presented demonstrating that Bmp4 expression in TS cells is controlled by mitogen-activated protein kinase-dependent FGF4 stimulation. Moreover, both the expression of Bmp4 in ExE and activation of Smad1/5 in epiblasts are reduced in Frs2alpha-null embryos. These experiments underscore the critical role of FRS2alpha in mediating multiple processes during embryonic development and reveal a potential new link between FGF and Bmp4 signaling pathways in early embryogenesis. 相似文献
58.
Go Y Rakotoarisoa G Kawamoto Y Shima T Koyama N Randrianjafy A Mora R Hirai H 《Primates; journal of primatology》2005,46(2):135-139
Major histocompatibility complex genes (Mhc-DQB and Mhc-DRB) were sequenced in seven aye-ayes (Daubentonia madagascariecsis), which is an endemic and endangered species in Madagascar. An aye-aye from a north-eastern population showed genetic relatedness to individuals of a north-western population and had a somewhat different repertoire from another north-eastern individual. These observations suggest that the extent of genetic variation in Mhc genes is not excessively small in the aye-aye in spite of recent rapid destruction of their habitat by human activities. In light of Mhc gene evolution, trans-species and allelic polymorphisms can be estimated to have been retained for more than 50 Ma (million years) based on the time scale of lemur evolution. 相似文献
59.
Kageyama H Funahashi H Hirayama M Takenoya F Kita T Kato S Sakurai J Lee EY Inoue S Date Y Nakazato M Kangawa K Shioda S 《Regulatory peptides》2005,126(1-2):67-71
Ghrelin, a novel peptide isolated from stomach tissue of rats and humans, has been identified as the endogenous ligand for the growth hormone secretagogue receptor (GHS-R). In addition to its secretion from the stomach, ghrelin is also expressed in the hypothalamic arcuate nucleus, intestine, kidney, placenta, and pancreas. GHS-R mRNA, on the other hand, is expressed in the hypothalamus, pituitary, heart, lung, liver, pancreas, stomach, intestine, and adipose tissue. Ghrelin is considered to have important roles in feeding regulation and energy metabolism as well as in the release of growth hormone (GH). Recent physiological experiments on the pancreas have shown that ghrelin regulates insulin secretion. However, sites of action of ghrelin in the pancreas are yet to be identified. In this study, to gain insight into the role of ghrelin in rat pancreatic islets, we used immunohistochemistry to determine the localization of ghrelin and GHS-R in islet cells. Double fluorescence immunohistochemistry revealed that weak GHS-R-like immunoreactivity was found in B cells containing insulin. GHS-R immunoreactivity overlapped that of glucagon-like immunoreactive cells. Moreover, both ghrelin and GHS-R-like immunoreactivities were detected mostly in the same cells in the periphery of the islets of Langerhans. These observations suggest that ghrelin is synthesized and secreted from A cells, and acts back on A cells in an autocrine and/or paracrine manner. In addition, ghrelin may act on B cells via GHS-R to regulate insulin secretion. 相似文献
60.
Isolation of human β-defensin-4 in lung tissue and its increase in lower respiratory tract infection
Shigehisa Yanagi Jun-ichi Ashitani Hiroshi Ishimoto Yukari Date Hiroshi Mukae Naoyoshi Chino Masamitsu Nakazato 《Respiratory research》2005,6(1):130