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排序方式: 共有866条查询结果,搜索用时 31 毫秒
81.
Functional dicer is necessary for appropriate specification of radial glia during early development of mouse telencephalon 总被引:1,自引:0,他引:1
Early telencephalic development involves transformation of neuroepithelial stem cells into radial glia, which are themselves neuronal progenitors, around the time when the tissue begins to generate postmitotic neurons. To achieve this transformation, radial precursors express a specific combination of proteins. We investigate the hypothesis that micro RNAs regulate the ability of the early telencephalic progenitors to establish radial glia. We ablate functional Dicer, which is required for the generation of mature micro RNAs, by conditionally mutating the Dicer1 gene in the early embryonic telencephalon and analyse the molecular specification of radial glia as well as their progeny, namely postmitotic neurons and basal progenitors. Conditional mutation of Dicer1 from the telencephalon at around embryonic day 8 does not prevent morphological development of radial glia, but their expression of Nestin, Sox9, and ErbB2 is abnormally low. The population of basal progenitors, which are generated by the radial glia, is disorganised and expanded in Dicer1-/- dorsal telencephalon. While the proportion of cells expressing markers of postmitotic neurons is unchanged, their laminar organisation in the telencephalic wall is disrupted suggesting a defect in radial glial guided migration. We found that the laminar disruption could not be accounted for by a reduction of the population of Cajal Retzius neurons. Together, our data suggest novel roles for micro RNAs during early development of progenitor cells in the embryonic telencephalon. 相似文献
82.
Zachara BA Szewczyk-Golec K Wolski Z Tyloch J Skok Z Bloch-Boguslawska E Wasowicz W 《Biological trace element research》2005,103(3):199-206
The dietary microelement selenium (Se) has been proposed as a potential chemopreventive agent for prostate cancer. This element
is present in various amounts in all tissues. Little information is available on Se level in patients with prostate gland
disorders. The levels of Se in prostatic gland of patients with prostate cancer, benign prostate hyperplasia, and healthy
controls were examined. The Se level for benign prostate hyperplasia (156±30.6 ng/g) was the same as in the control group
(157±26.0 ng/g), but in the gland of prostate cancer patients (182±34.1 ng/g wet weight), the Se level was significantly (p<0.01) higher than in both healthy controls and benign prostate hyperplasia. Thus, the Se level in human healthy controls
is lower than in kidney and liver but higher compared with other tissues. 相似文献
83.
Piotrowska-Nitsche K Perea-Gomez A Haraguchi S Zernicka-Goetz M 《Development (Cambridge, England)》2005,132(3):479-490
Blastomeres of the early mouse embryo are thought to be equivalent in their developmental properties at least until the eight-cell stage. However, the experiments that have led to this conclusion could not have taken into account either the spatial origin of individual blastomeres or the spatial allocation and fate of their progeny. We have therefore readdressed this issue having defined cell lineages in mouse embryos undergoing different patterns of cleavage in their second division cycle. This has enabled us to identify a major group of embryos in which we can predict not only the spatial origin of each given four-cell blastomeres, but also which region of the blastocyst is most likely to be occupied by its progeny. We show that a pattern of second cleavage divisions in which a meridional division is followed by one that is equatorial or oblique allows us to identify blastomeres that differ in their fate and in their developmental properties both from each other and from their cousins. We find that one of these four-cell stage blastomeres that inherits some vegetal membrane marked in the previous cleavage cycle tends to contribute to mural trophectoderm. The progeny of its sister tend to donate cells to part of the ICM lining the blastocyst cavity and its associated trophectoderm. Chimaeras made entirely of these equatorially or obliquely derived blastomeres show developmental abnormalities in both late preimplantation and early postimplantation development. By contrast, chimaeras made from four-cell stage blastomeres from early meridional divisions develop normally. The developmental defects of chimaeras made from the most vegetal blastomeres that result from later second cleavages are the most severe and following transplantation into foster mothers they fail to develop to term. However, when such individual four-cell blastomeres are surrounded by blastomeres from random positions, they are able to contribute to all embryonic lineages. In conclusion, this study shows that while all four-cell blastomeres can have full developmental potential, they differ in their individual developmental properties according to their origin in the embryo from as early as the four-cell stage. 相似文献
84.
The farnesylated SNARE (N-ethylmaleimide-sensitive factor attachment protein receptor) Ykt6 mediates protein palmitoylation at the yeast vacuole by means of its amino-terminal longin domain. Ykt6 is localized equally to membranes and the cytosol, although it is unclear how this distribution is mediated. We now show that Ykt6 is released efficiently from vacuoles during an early stage of yeast vacuole fusion. This release is dependent on the disassembly of vacuolar SNAREs (priming). In recent literature, it had been demonstrated for mammalian Ykt6 that the membrane-bound form is both palmitoylated and farnesylated at its carboxy-terminal CAAX box, whereas soluble Ykt6 is only farnesylated. In agreement with this, we find that yeast Ykt6 becomes palmitoylated in vitro at its C-terminal CAAX motif. Mutagenesis of the potential palmitoylation site in yeast Ykt6 prevents stable membrane association and is lethal. On the basis of these and other findings, we speculate that Ykt6 is released from membranes by depalmitoylation. Such a mechanism could enable recycling of this lipid-anchored SNARE from the vacuole independent of retrograde transport. 相似文献
85.
86.
Karolina Lindberg Anders Ström John G. Lock Jan‐Åke Gustafsson Lars‐Arne Haldosén Luisa A. Helguero 《Journal of cellular physiology》2010,222(1):156-167
Estrogen effects on mammary gland development and differentiation are mediated by two receptors (ERα and ERβ). Estrogen‐bound ERα induces proliferation of mammary epithelial and cancer cells, while ERβ is important for maintenance of the differentiated epithelium and inhibits proliferation in different cell systems. In addition, the normal breast contains higher ERβ levels compared to the early stage breast cancers, suggesting that loss of ERβ could be important in cancer development. Analysis of ERβ?/? mice has consistently revealed reduced expression of cell adhesion proteins. As such, ERβ is a candidate modulator of epithelial homeostasis and metastasis. Consequently, the aim of this study was to analyze estrogenic effects on adhesion of breast cancer cells expressing ERα and ERβ. As ERβ is widely found in breast cancer but not in cell lines, we used ERα positive T47‐D and MCF‐7 human breast cancer cells to generate cells with inducible ERβ expression. Furthermore, the colon cancer cell lines SW480 and HT‐29 were also used. Integrin α1 mRNA and protein levels increased following ERβ expression. Integrin β1—the unique partner for integrin α1—increased only at the protein level. ERβ expression enhanced the formation of vinculin containing focal complexes and actin filaments, indicating a more adhesive potential. This was confirmed by adhesion assays where ERβ increased adhesion to different extracellular matrix proteins, mostly laminin. In addition, ERβ expression was associated to less cell migration. These results indicate that ERβ affects integrin expression and clustering and consequently modulates adhesion and migration of breast cancer cells. J. Cell. Physiol. 222:156–167, 2010. © 2009 Wiley‐Liss, Inc. 相似文献
87.
Cruz MN Luksha L Logman H Poston L Agewall S Kublickiene K 《American journal of physiology. Heart and circulatory physiology》2006,290(5):H1969-H1975
The aim of this study was to investigate acute vasodilator responses to phytoestrogens and selective estrogen receptor-alpha (ERalpha) agonist in isolated small arteries from men with established coronary heart disease (CHD) and with a history of myocardial infarction versus healthy male control subjects. As to methodology, small arteries obtained from subcutaneous fat biopsies and mounted on a wire myograph were preconstricted with norepinephrine, and dilator responses to increasing nanomolar-micromolar concentrations of the phytoestrogens resveratrol and genistein (predominantly ERbeta agonists) and to propyl-[1H]-pyrazole-1,3,5-triyl-trisplenol (PPT, a selective ERalpha agonist) were determined. These were compared with responses to reference compound 17beta-estradiol (17beta-E2). Concentration-response curves were constructed before and after nitric oxide (NO) synthase inhibition with Nomega-nitro-L-arginine methyl ester. As a result, relaxation induced by the investigated compounds was similar in men with CHD and control men, but in both groups PPT and genistein-induced relaxation was greater than that of resveratrol and 17beta-E2. NO contributed to both phytoestrogens and PPT-induced relaxation but not to 17beta-E2 responses in arteries from control men. This NO-mediated component of relaxation was absent in arteries from men with established CHD. In conclusion, phytoestrogens, at concentrations achievable by ingestion of phytoestrogen-rich food products, evoke dilatation ex vivo of small peripheral arteries from normal men and those with established CHD. The contribution of NO to dilatory responses by these compounds is pertinent to arteries from control males, whereas other NO-independent dilatory mechanism(s) are involved in arteries from CHD. 相似文献
88.
89.
90.
Ma?gorzata Sowiak Karolina Bródka Alina Buczyńska Marcin Cyprowski Anna Kozajda Wojciech Sobala Irena Szadkowska-Stańczyk 《Aerobiologia》2012,28(2):121-133
The project was aimed at evaluating the potential occupational exposure of swine farm workers to dust and microorganisms present
in piggery bioaerosols (especially in its respirable fraction) under various breeding conditions. Sampling was carried out
in 14 buildings located at 13 pig breeding and production farms in Poland. Concentrations of inhalable and respirable dusts
in the air of the piggeries were low (means, respectively, 1.76 and 0.23 mg/m3). The concentration of microorganisms was generally high (mean = 3.53 × 105 cfu/m3). More than 96% of determined microorganisms were bacteria (mean = 3.42 × 105 cfu/m3). The fungal concentration was distinctly lower (mean = 2.71 × 103 cfu/m3). The concentration of bacteria in the respirable fraction of bioaerosol (mean = 1.51 × 105 cfu/m3) made up for 48.2% of their total concentration, while the level of fungi in that fraction (mean = 1.50 × 103 cfu/m3) formed 68.8% of the total fungal concentration. The concentration of inhalable dust was significantly modified by the type
of breeding system. The factors that significantly affected the total concentrations of microbes and bacteria, as well as
their levels in the bioaerosols’ respirable fraction were as follows: herd size, breeding system, feeding method and the type
of ventilation system. In the case of fungi, these were the livestock breeding system and the feeding method. Moreover, there
was a high positive correlation of inhalable dust concentrations with the fungal concentration, CO2 and relative humidity. A negative correlation was found between concentrations of each microbe group and the airflow velocity.
Swine farm workers are exposed to relatively low dust concentrations and high concentrations of microorganisms, bacteria in
particular. Fungi, to a much larger extent than bacteria, are correlated with the respirable particles of a piggery bioaerosol,
which may harm the respiratory system of exposed workers. 相似文献