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951.
James M. Daley YoungHo Kwon Hengyao Niu Patrick Sung 《The Yale journal of biology and medicine》2013,86(4):453-461
The DNA double-strand break (DSB), arising from exposure to ionizing radiation or
various chemotherapeutic agents or from replication fork collapse, is among the
most dangerous of chromosomal lesions. DSBs are highly cytotoxic and can lead to
translocations, deletions, duplications, or mutations if mishandled. DSBs are
eliminated by either homologous recombination (HR), which uses a homologous
template to guide accurate repair, or by nonhomologous end joining (NHEJ), which
simply rejoins the two broken ends after damaged nucleotides have been removed.
HR generates error-free repair products and is also required for generating
chromosome arm crossovers between homologous chromosomes in meiotic cells. The
HR reaction includes several distinct steps: resection of DNA ends, homologous
DNA pairing, DNA synthesis, and processing of HR intermediates. Each occurs in a
highly regulated fashion utilizing multiple protein factors. These steps are
being elucidated using a combination of genetic tools, cell-based assays, and
in vitro reconstitution with highly purified HR proteins.
In this review, we summarize contributions from our laboratory at Yale
University in understanding HR mechanisms in eukaryotic cells. 相似文献
952.
953.
Xin Zhang Zhibin Xiao Jianmin Yao Genshang Zhao Xianen Fa Jianli Niu 《Molecular and cellular biochemistry》2013,372(1-2):169-179
Activation of protein kinase C (PKC) is a critical intracellular signaling triggered by ischemic preconditioning (IPC), but the precise mechanisms underlying the actions of PKC in IPC-mediated cardioprotection remain unclear. Here, we investigated the role of PKC activation on the antioxidant activity by IPC in rabbit hearts. Isolated rabbit hearts were subjected to 60?min of global ischemia by cold cardioplegic arrest (4?°C) and 60?min of reperfusion (37?°C). IPC was induced by three cycles of 2-min ischemia following 3?min of reperfusion (37?°C) before cardioplegic arrest. IPC resulted in a better recovery of mechanical function, increased tissue reduced glutathione-to-oxidized glutathione ratio (GSH/GSSG), superoxide dismutase and catalase content, and decreased tissue malondialdehyde (MDA) content compared to control hearts subjected to 60?min of cardioplegic ischemia and 60?min of reperfusion. IPC also significantly induced activation of nuclear factor erythroid 2-related factor 2 (Nrf2) and the inductions of antioxidant genes heme oxygenase-1 (HO-1) and manganese superoxide dismutase (MnSOD). Injection of phorbol 12-myristate 13 acetate, an activator of PKC, before cardioplegic ischemia induced translocation of PKC-?? and -?? isoforms to membrane fraction, nuclear accumulation of Nrf2, and conferred cardioprotection similar to IPC. Polymyxin B, an inhibitor of PKC, blocked the membrane translocation of PKC-?? and -?? during IPC, inhibited Nrf2 nuclear accumulation, and significantly diminished the IPC-induced cardioprotection when administrated before IPC. These results indicate that the activation of PKC induces the translocation of Nrf2 and the enhancement of endogenous antioxidant defenses in the IPC hearts and suggest that PKC may target Nrf2 to confer cardioprotection. 相似文献
954.
Weiwei Zhang Zongliang Niu Chunyang Liao Lingxin Chen 《Applied microbiology and biotechnology》2013,97(9):4095-4104
Since diethylstilbestrol (DES) interrupts endocrine systems and generates reproductive abnormalities in both wildlife and human beings, methods to remove DES from the environments are urgently recommended. In this study, bacterial strain J51 was isolated and tested to effectively degrade DES. J51 was identified as Pseudomonas sp. based on its nucleotide sequence of 16S rRNA. The quinoprotein alcohol dehydrogenase and isocitrate lyase were identified to be involved in DES degradation by MALDI–TOF–TOF MS/MS analysis. In the presence of 40 mg/l DES, increase of the genes encoding quinoprotein alcohol dehydrogenase and isocitrate lyase in both RNA and protein levels was determined. The HPLC/MS analysis showed that DES was hydrolyzed to a major degrading metabolite DES-4-semiquinone. It was the first time to demonstrate the characteristics of DES degradation by specific bacterial strain and the higher degradation efficiency indicated the potential application of Pseudomonas sp. strain J51 in the treatment of DES-contaminated freshwater and seawater environments. 相似文献
955.
Deyao Du Yu Zhu Junhong Wei Yuqing Tian Guoqing Niu Huarong Tan 《Applied microbiology and biotechnology》2013,97(14):6383-6396
Nikkomycins and gougerotin are peptidyl nucleoside antibiotics with broad biological activities. The nikkomycin biosynthetic gene cluster comprises one pathway-specific regulatory gene (sanG) and 21 structural genes, whereas the gene cluster for gougerotin biosynthesis includes one putative regulatory gene, one major facilitator superfamily transporter gene, and 13 structural genes. In the present study, we introduced sanG driven by six different promoters into Streptomyces ansochromogenes TH322. Nikkomycin production was increased significantly with the highest increase in engineered strain harboring hrdB promoter-driven sanG. In the meantime, we replaced the native promoter of key structural genes in the gougerotin (gou) gene cluster with the hrdB promoters. The heterologous producer Streptomyces coelicolor M1146 harboring the modified gene cluster produced gougerotin up to 10-fold more than strains carrying the unmodified cluster. Therefore, genetic manipulations of genes involved in antibiotics biosynthesis with the constitutive hrdB promoter present a robust, easy-to-use system generally useful for the improvement of antibiotics production in Streptomyces. 相似文献
956.
957.
Chia-Hao Chin Shu-Hwa Chen Chun-Yu Chen Chao A. Hsiung Chin-Wen Ho Ming-Tat Ko Chung-Yen Lin 《Gene》2013
As is generally assumed, clusters in protein–protein interaction (PPI) networks perform specific, crucial functions in biological systems. Various network community detection methods have been developed to exploit PPI networks in order to identify protein complexes and functional modules. Due to the potential role of various regulatory modes in biological networks, a single method may just apply a single graph property and neglect communities highlighted by other network properties. 相似文献
958.
X-linked adrenoleukodystrophy (X-ALD) is a neurodegenerative disorder resulting from mutations within the ABCD1 gene. Adrenomyeloneuropathy (AMN) and childhood cerebral ALD (CCALD) are most common phenotypes in the Western ALD patients. Here we performed mutation analysis of ABCD1 in 10 Chinese ALD families and identified 8 mutations, including one novel deletion (c.1477_1488 + 11del23) and 7 known mutations. Mutations c.1772G>A and c.1816T>C were first reported in the Chinese patients. Mutations c.1661G>A and c.1679C>T were demonstrated to be de novo mutations. The dinucleotide deletion 1415_16delAG, described as a mutational hotspot in different ethnic groups, was identified in two families. In addition, we performed a retrospective nation-wide mutation study of X-linked ALD in China based on a literature review. The retrospective study further confirmed the hypothesis that exon 6 is a potential mutation cluster region in the Asian populations. Furthermore, it suggested that CCALD is the most common phenotype in China. 相似文献
959.
Rong Wang Hui Gao Wei Xu Hui Li Yiqing Mao Yi Wang Tingting Guo Xi Wang Rongjing Song Zhixin Li David M. Irwin Gang Niu Huanran Tan 《Gene》2013
To investigate the role of liver-specific expression of glucokinase (GCK) in the pathogenesis of hyperglycemia and to identify candidate genes involved in mechanisms of the onset and progression of maturity onset diabetes of the young, type 2 (MODY-2), we examined changes in biochemical parameters and gene expression in GCK knockout (gckw/–) and wild-type (gckw/w) mice as they aged. Fasting blood glucose levels were found to be significantly higher in the gckw/– mice, compared to age-matched gckw/w mice, at all ages (P < 0.05), except at 2 weeks. GCK activity of gckw/– mice was about 50% of that of wild type (gckw/w) mice (P < 0.05). Glycogen content at 4 and 40 weeks of age was lower in gckw/– mice compared to gckw/w mice. Differentially expressed genes in the livers of 2 and 26 week-old liver-specific GCK knockout (gckw/–) mice were identified by suppression subtractive hybridization (SSH), which resulted in the identification of phosphoenolpyruvatecarboxykinase (PEPCK, also called PCK1) and Sterol O-acyltransferase 2 (SOAT2) as candidate genes involved in pathogenesis. The expressions of PEPCK and SOAT2 along with glycogen phosphorylase (GP) and glycogen synthase (GS) were then examined in GCK knockout (gckw/–) and wild-type (gckw/w) mice at different ages. Changes in PEPCK mRNA levels were confirmed by real-time RT-PCR, while no differences in the levels of expression of SOAT2 or GS were observed in age-matched GCK knockout (gckw/–) and wild-type (gckw/w) mice. GP mRNA levels were decreased in 40-week old gckw/– mice compared to age-matched gckw/w mice. Changes in gluconeogenesis, delayed development of GCK and impaired hepatic glycogen synthesis in the liver potentially lead to the onset and progression of MODY2. 相似文献
960.
Yan‐shan Niu Zi‐zheng Cai Yan Lu Mei‐xian Wang Shuang Liang Fang Zhou Yun‐gen Miao 《Archives of insect biochemistry and physiology》2013,82(2):84-95
To investigate the function of adaptor protein complex‐1 (AP‐1) in the silkworm, we characterized AP‐1 in the silkworm by RNAi technique and co‐localization methods. As a result, AP‐1 was found to exist as cytosolic form and membrane‐bound form distinguished by phosphate status, showing molecular mass difference. There was relatively more cytosolic form of AP‐1 than its membrane‐bound counterpart in the silkworm. However, AP‐1 distributed predominantly as cytosolic form in BmN cells. Interruption of AP‐1 expression via DsRNA was more efficient in BmN cells than in the insect larval, which led to a tendency to dissociation between subcellular organelles like the Golgi apparatus and the mitochondria. Environmental condition changes like relatively higher temperature and treatment with dimethyl sulfoxide can lead to expression variance of AP‐1 both in mRNA and protein level. In BmN cells, both the heavy chain γ and light chain σ could clearly co‐localize with AP‐1 β, mostly forming pits in cytoplasm. Two isoforms of AP‐1 σ corresponded to distinct subcellular distribution pattern, possibly due to C‐terminal amino acids difference. 相似文献