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991.
992.
On the basis of the evidence of the enhanced susceptibility to kainate-induced seizures in young rats fed a zinc-deficient
diet for 4 weeks, the relationship between zinc release from hippocampal neuron terminals and seizure susceptibility was studied
in young rats fed the zinc-deficient diet for 2 weeks. Timm’s stain, with which histochemically reactive zinc in the presynaptic
vesicle is detected, was not attenuated in mossy fibers and other areas in the hippocampus after 2-week zinc deprivation,
whereas the attenuation was observed after 4-week zinc deprivation. Extracellular zinc concentration was not also decreased
after 2-week zinc deprivation, unlike the case after 4-week zinc deprivation. To check the capacity for zinc release from
neuron terminals after 2-week zinc deprivation, the hippocampus was excessively stimulated with 100 mM KCl. The increase in
extracellular zinc concentration of zinc-deficient group was significantly more than that of control group. These results
suggest that zinc release from hippocampal neuron terminals is not affected by 2-week zinc deprivation. On the other hand,
the latency in myoclonic jerks of zinc-deficient group was significantly shorter than in the control group after treatment
with kainate, while the latency in clonic convulsions was not different between the two groups. Intracellular fura-2 signal,
a calcium indicator, was significantly higher in the hippocampal CA3 areas of zinc-deficient group 4 s after delivery of kainate
to dentate granule cells. These results suggest that susceptibility to kainate-induced seizures is altered prior to the decrease
in extracellular zinc concentration and zinc release from neuron terminals in zinc-deficient young rats. The alteration of
calcium signaling seems to be involved in the susceptibility in zinc deficiency. 相似文献
993.
Atsushi Ikai Masaaki Nishigai Toshiya Osada Hideo Arakawa Masako Kikuchi 《The protein journal》1987,6(1):81-93
The plasma α2-macroglobulin and its egg white homologue ovomacroglobulin were purified from several different species and their structure before and after the reaction with proteinases studied by electron microscopy. The negatively stained specimens showed either a ringlike structure or a flowerlike one before the reaction with proteinses, but their structures changed into open rectangular ones after the reaction. The translational frictional ratio f/f 0 of human α2-macroglobulin and crocodilian ovomacroglobulin given in the literature is between 1.5 and 1.6 before and after the reaction with proteinases. The value reflects asymmetry due not to a high axial ratio, but rather to an openness of the structure resulting in a partially free draining character of the molecules. The computational method developed by Bloomfield and his co-workers based on the formalism of Kirkwood is used to calculate the frictional ratio of several models constructed from small spheres. The overall shape of the models is derived from electron micrographs. Although the degree of hydration is an unknown parameter in the calculation, reasonable agreement is obtained between the experimental values of f/f 0 and the calculated ones. Combination of electron microscopic and hydrodynamic methods would be fruitful in the structural study of giant proteins such as α2-macroglobulin. 相似文献
994.
Putative "stemness" gene jam-B is not required for maintenance of stem cell state in embryonic, neural, or hematopoietic stem cells 下载免费PDF全文
Sakaguchi T Nishimoto M Miyagi S Iwama A Morita Y Iwamori N Nakauchi H Kiyonari H Muramatsu M Okuda A 《Molecular and cellular biology》2006,26(17):6557-6570
Many genes have been identified that are specifically expressed in multiple types of stem cells in their undifferentiated state. It is generally assumed that at least some of these putative "stemness" genes are involved in maintaining properties that are common to all stem cells. We compared gene expression profiles between undifferentiated and differentiated embryonic stem cells (ESCs) using DNA microarrays. We identified several genes with much greater signal in undifferentiated ESCs than in their differentiated derivatives, among them the putative stemness gene encoding junctional adhesion molecule B (Jam-B gene). However, in spite of the specific expression in undifferentiated ESCs, Jam-B mutant ESCs had normal morphology and pluripotency. Furthermore, Jam-B homozygous mutant mice are fertile and have no overt developmental defects. Moreover, we found that neural and hematopoietic stem cells recovered from Jam-B mutant mice are not impaired in their ability to self-renew and differentiate. These results demonstrate that Jam-B is dispensable for normal mouse development and stem cell identity in embryonic, neural, and hematopoietic stem cells. 相似文献
995.
Noguchi T Takeda K Matsuzawa A Saegusa K Nakano H Gohda J Inoue J Ichijo H 《The Journal of biological chemistry》2005,280(44):37033-37040
Apoptosis signal-regulating kinase 1 (ASK1) plays a pivotal role in oxidative stress-induced cell death. Reactive oxygen species disrupt the interaction of ASK1 with its cellular inhibitor thioredoxin and thereby activates ASK1. However, the precise mechanism by which ASK1 freed from thioredoxin undergoes oligomerization-dependent activation has not been fully elucidated. Here we show that endogenous ASK1 constitutively forms a high molecular mass complex including Trx ( approximately 1,500-2,000 kDa), which we designate ASK1 signalosome. Upon H(2)O(2) treatment, the ASK1 signalosome forms a higher molecular mass complex at least in part because of the recruitment of tumor necrosis factor receptor-associated factor 2 (TRAF2) and TRAF6. Consistent with our previous findings that TRAF2 and TRAF6 activate ASK1, H(2)O(2)-induced ASK1 activation and cell death were strongly reduced in the cells derived from Traf2-/- and Traf6-/- mice. A novel signaling complex including TRAF2, TRAF6, and ASK1 may thus be the key component in oxidative stress-induced cell death. 相似文献
996.
Hideaki Yuasa Rei Kajitani Yuta Nakamura Kazuki Takahashi Miki Okuno Fumiya Kobayashi Takahiro Shinoda Atsushi Toyoda Yutaka Suzuki Nalinee Thongtham Zac Forsman Omri Bronstein Davide Seveso Enrico Montalbetti Coralie Taquet Gal Eyal Nina Yasuda Takehiko Itoh 《DNA research》2021,28(4)
The crown-of-thorns starfish (COTS) is a coral predator that is widely distributed in Indo-Pacific Oceans. A previous phylogenetic study using partial mitochondrial sequences suggested that COTS had diverged into four distinct species, but a nuclear genome-based analysis to confirm this was not conducted. To address this, COTS species nuclear genome sequences were analysed here, sequencing Northern Indian Ocean (NIO) and Red Sea (RS) species genomes for the first time, followed by a comparative analysis with the Pacific Ocean (PO) species. Phylogenetic analysis and ADMIXTURE analysis revealed clear divergences between the three COTS species. Furthermore, within the PO species, the phylogenetic position of the Hawaiian sample was further away from the other Pacific-derived samples than expected based on the mitochondrial data, suggesting that it may be a PO subspecies. The pairwise sequentially Markovian coalescent model showed that the trajectories of the population size diverged by region during the Mid-Pleistocene transition when the sea-level was dramatically decreased, strongly suggesting that the three COTS species experienced allopatric speciation. Analysis of the orthologues indicated that there were remarkable genes with species-specific positive selection in the genomes of the PO and RS species, which suggested that there may be local adaptations in the COTS species. 相似文献
997.
Chromatin structure is strictly regulated during the cell cycle. DNA viruses occasionally disturb the spatial organization of the host cell chromatin due to formation of the viral DNA replication compartment. To examine chromatin behavior in baculovirus-infected cells, we constructed recombinant plasmids expressing fluorescent protein-tagged histone H4 molecules and visualized the intracellular localization of chromatin by their transient expression in live infected cells. Similar to other DNA viruses, the baculovirus Bombyx mori nucleopolyhedrovirus induced marginal relocation of chromatin within the nuclei of BmN cells, simultaneously with expansion of the viral DNA replication compartment, the virogenic stroma (VS). In the late stage of infection, however, the peristromal region (PR), another virus-induced subnuclear compartment, was also excluded from the chromatin-localizing area. Provided that late-gene products such as PR proteins (e.g., envelope proteins of the occlusion-derived virus) were expressed, blockage of viral DNA synthesis failed to inhibit chromatin relocation, despite abrogation of VS expansion. Instead, chromatin became marginalized concomitantly with PR expansion, suggesting that the PR contributes directly to chromatin replacement. In addition, chromatin was excluded from relatively large subnuclear structures that were induced in uninfected cells by cotransfection with four baculovirus genes, ie1, lef3, p143, and hr. Omission of any of the four genes, however, failed to result in formation of the large structures or chromatin exclusion. This correlation between compartmentalization and chromatin exclusion suggests the possibility that a chromatin-exclusive property of viral molecules, at least in part, supports nuclear compartmentalization of virus-infected cells. 相似文献
998.
999.
Tomomi Shida-Sakazume Yosuke Endo-Sakamoto Motoharu Unozawa Chonji Fukumoto Ken Shimada Atsushi Kasamatsu Katsunori Ogawara Hidetaka Yokoe Masashi Shiiba Hideki Tanzawa Katsuhiro Uzawa 《PloS one》2015,10(3)
Background
The relevance of lysophosphatidylcholine acyltransferase1 (LPCAT1), a cytosolic enzyme in the remodeling pathway of phosphatidylcholine metabolism, in oral squamous cell carcinoma (OSCC) is unknown. We investigated LPCAT1 expression and its functional mechanism in OSCCs.Methods
We analyzed LPCAT1 mRNA and protein expression levels in OSCC-derived cell lines. Immunohistochemistry was performed to identify correlations between LPCAT1 expression levels and primary OSCCs clinicopathological status. We established LPCAT1 knockdown models of the OSCC-derived cell lines (SAS, Ca9-22) for functional analysis and examined the association between LPCAT1 expression and the platelet-activating factor (PAF) concentration and PAF-receptor (PAFR) expression.Results
LPCAT1 mRNA and protein were up-regulated significantly (p<0.05) in OSCC-derived cell lines compared with human normal oral keratinocytes. Immunohistochemistry showed significantly (p<0.05) elevated LPCAT1 expression in primary OSCCs compared with normal counterparts and a strong correlation between LPCAT1-positive OSCCs and tumoral size and regional lymph node metastasis. In LPCAT1 knockdown cells, cellular proliferation and invasiveness decreased significantly (p<0.05); cellular migration was inhibited compared with control cells. Down-regulation of LPCAT1 resulted in a decreased intercellular PAF concentration and PAFR expression.Conclusion
LPCAT1 was overexpressed in OSCCs and correlated with cellular invasiveness and migration. LPCAT1 may contribute to tumoral growth and metastasis in oral cancer. 相似文献1000.
Linda C. McCarthy Marie-Therese Bihoreau Susanna L. Kiguwa Julie Browne Takeshi K. Watanabe Haretsugu Hishigaki Atsushi Tsuji Susanne Kiel Caleb Webber Maria E. Davis Catherine Knights Angela Smith Ricky Critcher Patrick Huxtall James R. Hudson Jr. Toshihide Ono Hiroumi Hayashi Toshihisa Takagi Yusuke Nakamura Akira Tanigami Peter N. Goodfellow G. Mark Lathrop Michael R. James 《Mammalian genome》2000,11(9):791-795