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991.
992.
PlexinD1 signaling controls morphological changes and migration termination in newborn neurons 下载免费PDF全文
Masato Sawada Nobuhiko Ohno Mitsuyasu Kawaguchi Shih‐hui Huang Takao Hikita Youmei Sakurai Huy Bang Nguyen Truc Quynh Thai Yuri Ishido Yutaka Yoshida Hidehiko Nakagawa Akiyoshi Uemura Kazunobu Sawamoto 《The EMBO journal》2018,37(4)
Newborn neurons maintain a very simple, bipolar shape, while they migrate from their birthplace toward their destinations in the brain, where they differentiate into mature neurons with complex dendritic morphologies. Here, we report a mechanism by which the termination of neuronal migration is maintained in the postnatal olfactory bulb (OB). During neuronal deceleration in the OB, newborn neurons transiently extend a protrusion from the proximal part of their leading process in the resting phase, which we refer to as a filopodium‐like lateral protrusion (FLP). The FLP formation is induced by PlexinD1 downregulation and local Rac1 activation, which coincide with microtubule reorganization and the pausing of somal translocation. The somal translocation of resting neurons is suppressed by microtubule polymerization within the FLP. The timing of neuronal migration termination, controlled by Sema3E‐PlexinD1‐Rac1 signaling, influences the final positioning, dendritic patterns, and functions of the neurons in the OB. These results suggest that PlexinD1 signaling controls FLP formation and the termination of neuronal migration through a precise control of microtubule dynamics. 相似文献
993.
Yu-Wei Wu Xiaofang Tang Misa Arizono Hiroko Bannai Pei-Yu Shih Yulia Dembitskaya Victor Kazantsev Mika Tanaka Shigeyoshi Itohara Katsuhiko Mikoshiba Alexey Semyanov 《Cell calcium》2014
Astrocytes produce a complex repertoire of Ca2+ events that coordinate their major functions. The principle of Ca2+ events integration in astrocytes, however, is unknown. Here we analyze whole Ca2+ events, which were defined as spatiotemporally interconnected transient Ca2+ increases. Using such analysis in single hippocampal astrocytes in culture and in slices we found that spreads and durations of Ca2+ events follow power law distributions, a fingerprint of scale-free systems. A mathematical model demonstrated that such Ca2+ dynamics can arise from intracellular inositol-3-phosphate diffusion. The power law exponent (α) was decreased by activation of metabotropic glutamate receptors (mGluRs) either by specific receptor agonist or by low frequency stimulation of glutamatergic fibers in hippocampal slices. Decrease in α indicated an increase in proportion of large Ca2+ events. Notably, mGluRs activation did not increase the frequency of whole Ca2+ events. This result suggests that neuronal activity does not trigger new Ca2+ events in astrocytes (detectable by our methods), but modulates the properties of existing ones. Thus, our results provide a new perspective on how astrocyte responds to neuronal activity by changing its Ca2+ dynamics, which might further affect local network by triggering release of gliotransmitters and by modulating local blood flow. 相似文献
994.
Tzu‐Hung Lin Chih‐Hsin Tang Shih‐Ya Hung Shing‐Hwa Liu Yen‐Ming Lin Wen‐Mei Fu Rong‐Sen Yang 《Journal of cellular physiology》2010,222(3):757-768
Heme‐oxygenase‐1 (HO‐1), an important enzyme involved in vascular disease, transplantation, and inflammation, catalyzes the degradation of heme into carbon monoxide and biliverdin. It has been reported that overexpression of HO‐1 inhibits osteoclastogenesis. However, the effect of HO‐1 on osteoblast differentiation is still not clear. We here used adenoviral vector expressing recombinant human HO‐1 and HO‐1 inducer hemin to study the effects of HO‐1 in primary cultured osteoblasts. The results showed that induction of HO‐1 inhibited the maturation of osteoblasts including mineralized bone nodule formation, alkaline phosphatase activity and decreased mRNA expression of several differentiation markers such as alkaline phosphatase, osteocalcin, and RUNX2. Furthermore, downstream products of HO‐1, bilirubin, carbon monoxide, and iron, are involved in the inhibitory action of HO‐1. HO‐1 can be induced by H2O2, lipopolysaccharide and inflammatory cytokines such as TNF‐α and IL‐1β in osteoblasts and also in STZ‐induced diabetic mice. In addition, endogenous PPARγ ligand, 15‐deoxy‐Δ12,14‐prostaglandin‐J2 (15d‐PGJ2) markedly increased both mRNA and protein levels of HO‐1 in osteoblasts via PI3K‐Akt and MAPK pathways. Blockade of HO activity by ZnPP IX antagonized the inhibitory action on osteocalcin expression by hemin and 15d‐PGJ2. Our results indicate that upregulation of HO‐1 inhibits the maturation of osteoblasts and HO‐1 may be involved in oxidative‐ or inflammation‐induced bone loss. J. Cell. Physiol. 222: 757–768, 2010. © 2009 Wiley‐Liss, Inc. 相似文献
995.
The polyamines putrescine, spermidine, and spermine and their biosynthetic enzymes arginine decarboxylase, ornithine decarboxylase and S-adenosyl-l-methionine decarboxylase are present in all parts of dormant potato (Solanum tuberosum L.) tubers. They are equally distributed among the buds of apical and lateral regions and in nonbud tissues. However, the breaking of dormancy and initiation of sprouting in the apical bud region are accompanied by a rapid increase in ornithine decarboxylase and S-adenosyl-l-methionine decarboxylase activities, as well as by higher levels of putrescine, spermidine, and spermine in the apical buds. In contrast, the polyamine biosynthetic enzyme activities and titer remain practically unchanged in the dormant lateral buds and in the nonbud tissues. The rapid rise in ornithine decarboxylase, but not arginine decarboxylase activity, with initiation of sprouting suggests that ornithine decarboxylase is the rate-limiting enzyme in polyamine biosynthesis. The low level of polyamine synthesis during dormancy and its dramatic increase in buds in the apical region at break of dormancy suggest that polyamine synthesis is linked to sprouting, perhaps causally. 相似文献
996.
半灌木(?),高1.5米。茎枝及接花序处被白色稠密短柔毛。大部茎叶为菱形,长1-1.4厘米,宽0.7-1.5厘米,边缘每侧各有一个三角形或斜三角形的浅裂片或钝齿,接花序下部的叶椭圆形、卵形或宽线形,长约1厘米,宽0.5-0.6厘米,全缘不裂。 相似文献
997.
The ornithine aminotransferase (OAT) locus: analysis of RFLPs in gyrate atrophy. 总被引:4,自引:2,他引:4 下载免费PDF全文
V Ramesh L A Benoit P Crawford P T Harvey T B Shows V E Shih J F Gusella 《American journal of human genetics》1988,42(2):365-372
A cDNA probe (HOAT1) for ornithine aminotransferase (OAT) has recently been used to map (1) the structural gene for this enzyme to chromosome 10 and (2) several related DNA sequences to the X chromosome. We have defined six RFLPs for OAT, to explore its possible role in gyrate atrophy (GA) of the choroid and retina, an autosomal recessive genetic disorder associated with a deficiency of OAT activity. The RFLPs, which are detected by noncoding single-copy probes from the OAT gene and by subclones of the HOAT1 cDNA, all map on human chromosome 10, producing an overall level of heterozygosity for the OAT locus of 83%. Using the RFLPs, we have determined that the OAT locus segregates concordantly with GA in one available pedigree. Furthermore, the RFLPs display significant disequilibrium with GA, providing genetic evidence implicating a defect in the OAT structural gene as the cause of this disorder. The RFLPs for OAT are potentially applicable to prenatal diagnosis and carrier detection in families with a previous history of GA. They will also allow identification of specific haplotypes associated with GA chromosomes, as a guide for more detailed molecular-genetic investigations of the mutations underlying the disorder. 相似文献
998.
Xuefeng Wang Liyang Dong Hongchang Ni Sha Zhou Zhipeng Xu Jason Shih Hoellwarth Xiaojun Chen Rongbo Zhang Qiaoyun Chen Feng Liu Jun Wang Chuan Su 《PLoS neglected tropical diseases》2013,7(4)
Background
Toll-like receptor (TLR) ligands have been explored as vaccine adjuvants for tumor and virus immunotherapy, but few TLR ligands affecting schistosoma vaccines have been characterized. Previously, we developed a partially protective DNA vaccine encoding the 26-kDa glutathione S-transferase of Schistosoma japonicum (pVAX1-Sj26GST).Methodology/Principal Findings
In this study, we evaluated a TLR7/8 ligand (R848) and a TLR9 ligand (CpG oligodeoxynucleotides, or CpG) as adjuvants for pVAX1-Sj26GST and assessed their effects on the immune system and protection against S. japonicum. We show that combining CpG and R848 with pVAX1-Sj26GST immunization significantly increases splenocyte proliferation and IgG and IgG2a levels, decreases CD4+CD25+Foxp3+ regulatory T cells (Treg) frequency in vivo, and enhances protection against S. japonicum. CpG and R848 inhibited Treg-mediated immunosuppression, upregulated the production of interferon (IFN)-γ, tumor necrosis factor (TNF)-α, interleukin (IL)-4, IL-10, IL-2, and IL-6, and decreased Foxp3 expression in vitro, which may contribute to prevent Treg suppression and conversion during vaccination and allow expansion of antigen-specific T cells against pathogens.Conclusions
Our data shows that selective TLR ligands can increase the protective efficacy of DNA vaccines against schistosomiasis, potentially through combined antagonism of Treg-mediated immunosuppression and conversion. 相似文献999.
Geographic variations among infectious hypodermal and hematopoietic necrosis virus (IHHNV) isolates and characteristics of their infection 总被引:7,自引:0,他引:7
Tang KF Poulos BT Wang J Redman RM Shih HH Lightner DV 《Diseases of aquatic organisms》2003,53(2):91-99
Nucleotide sequence variations of a 2.9 kb fragment of infectious hypodermal and hematopoietic necrosis virus (IHHNV) isolated from samples of Penaeus monodon were determined and compared with an isolate from Hawaii. The infection characteristics of these isolates were examined by histology, in situ hybridization, and laboratory challenge studies with P. vannamei. Isolates of IHHNV were obtained from samples collected from the SE Asia region (the Philippines, Thailand, and Taiwan). Isolates of putative IHHNV were obtained from African samples (Tanzania, Madagascar, and Mauritius). The Philippine isolate had a very high nucleotide sequence identity (99.8%) to Hawaii IHHNV. The Thailand isolate showed a slightly lower identity (96.2%). The putative IHHNV sequences collected from Tanzania and Madagascar showed greater divergence from Hawaii IHHNV, 8.2% difference for Tanzania and 14.1% difference for Madagascar. A phylogenetic analysis showed that the Philippine IHHNV clustered with IHHNV found in the western hemisphere. This supports the theory that the Philippines was the origin of IHHNV that was first detected in Hawaii. In the laboratory infection study, both the Philippine and Thailand IHHNV were passed into P. vannamei, and the infected shrimp did not suffer any mortalities. In another laboratory infection, P. vannamei injected with a tissue homogenate of P. monodon from Madagascar, which tested positive for IHHNV by PCR, did not demonstrate IHHNV infection, suggesting that this putative IHHNV is not infectious to P. vannamei. 相似文献
1000.