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991.
Despite the current availability of several hundreds of thousands of amino acid sequences, more than 39% of the well-defined
enzyme activities (EC numbers) are not associated with any sequence in major public databases. This wide gap separating knowledge
of biochemical function and sequence information is found in nearly all classes of enzymes. Thus, there is an urgent need
to explore the 1525 orphan enzymes (EC numbers without associated sequences), in order to progressively bridge this unwanted
gap. Improving genome annotation could unveil a significant proportion of sequenceless enzymes. Peptide mass mapping and further
genome mining would be useful to identify proper sequence for enzymes found in species for which genetic tools are missing.
Finally, the whole community must help major public databases to begin addressing the problem of missing or incomplete information.
Received 31 October 2005; received after revision 8 December 2005; accepted 20 December 2005 相似文献
992.
Olfactory ensheathing cells have been used in several studies to promote repair in the injured spinal cord. However, cellular
interaction between olfactory ensheathing cells and glial cells induced to be reactive in the aftermath of injury site has
not been investigated. Using an in vitro model of astrogliosis, we show that reactive astrocytes expressed significantly less glial fibrillary acidic protein (GFAP)
when cultured both in direct contact with olfactory ensheathing cells and when the two cell types were separated by a porous
membrane. Immunofluorescence staining also suggested that reactive astrocytes showed decreased chondroitin sulfate proteoglycans
in the presence of olfactory ensheathing cells, although the reduction was not statistically significant. No down-regulation
of GFAP was observed when reactive astrocytes were similarly cultured with Schwann cells. Cell viability assay and bromodeoxyuridine
uptake showed that proliferation of reactive astrocytes was significantly increased in the presence of olfactory ensheathing
cells and Schwann cells.
Received 27 February 2007; received after revision 30 March 2007; accepted 3 April 2007 相似文献
993.
Hurtaud C Gelly C Chen Z Lévi-Meyrueis C Bouillaud F 《Cellular and molecular life sciences : CMLS》2007,64(14):1853-1860
Uncoupling protein 2 (UCP2) belongs to a family of transporters/exchangers of the mitochondrial inner membrane. Using cell
lines representing natural sites of UCP2 expression (macrophages, colonocytes, pancreatic beta cells), we show that UCP2 expression
is stimulated by glutamine at physiological concentrations. This control is exerted at the translational level. We demonstrate
that the upstream open reading frame (ORF1) in the 5’ untranslated region (5’UTR) of the UCP2 mRNA is required for this stimulation
to take place. Cloning of the 5’ UTR of the UCP2 mRNA in front of a GFP cDNA resulted in a reporter gene with which GFP expression
could be induced by glutamine. An effect of glutamine on translation of a given mRNA has not been identified before, and this
is the first evidence for a link between UCP2 and glutamine, an amino acid oxidized by immune cells or intestinal epithelium
and playing a role in the control of insulin secretion.
Received 26 January 2007; received after revision 16 April 2007; accepted 8 May 2007
C. Hurtaud, C. Gelly: These authors contributed equally to this work. 相似文献
994.
As the site of gene expression and regulation, the nucleus is the control center of the cell. It might be thought that degradation
of nuclear contents is strictly ‘off-limits,’ given the importance of the genetic information contained within the nucleus,
but it has recently been reported that partial degradation of the nucleus may occur in yeast. Here we summarize the evidence
for the degradation and quality control of proteins found with the nucleus and its compartments, and of nucleic acids that
may occur under certain specific conditions. Only under certain special conditions such as differentiation of the lens are
the entire nuclear contents degraded.
Received 6 September 2006; received after revision 25 October 2006; accepted 13 December 2006 相似文献
995.
Tsatsanis C Dermitzaki E Venihaki M Chatzaki E Minas V Gravanis A Margioris AN 《Cellular and molecular life sciences : CMLS》2007,64(13):1638-1655
Corticotropin-releasing factor (CRF), also termed corticotropin-releasing hormone (CRH) or corticoliberin, is the major regulator
of the adaptive response to internal or external stresses. An essential component of the adaptation mechanism is the adrenal
gland. CRF regulates adrenal function indirectly through the central nervous system (CNS) via the hypothalamic-pituitary-adrenal
(HPA) axis and via the autonomic nervous system by way of locus coeruleus (LC) in the brain stem. Accumulating evidence suggests
that CRF and its related peptides also affect the adrenals directly, i.e. not through the CNS but from within the adrenal gland where they form paracrine regulatory loops. Indeed, CRF and its related
peptides, the urocortins (UCNs: UCN1, UCN2 and UCN3), their receptors CRF type 1 (CRF1) and 2 (CRF2) as well as the endogenous pseudo-receptor CRF-binding protein (CRF-BP) are all expressed in adrenal cortical, medullary
chromaffin and resident immune cells. The intra-adrenal CRF-based regulatory system is complex and depends on the balance
between the local concentration of CRF ligands and the availability of their receptors.
Received 19 December 2006; received after revision 20 February 2007; accepted 26 March 2007 相似文献
996.
From Creutzfeldt-Jakob disease (CJD) to variant CJD through Gerstmann-Str?ussler-Scheinker syndrome, kuru and fatal familial insomnia, the journey leading to current understanding of the basic aspects of human prion diseases has been full of unexpected, but often dramatic and always fascinating twists. Recent progress in modeling prion diseases and characterization of the various prion protein forms reveal that such a wide spectrum of the diseases is associated with the chameleon-like conformational features of prions. 相似文献
997.
Garbern JY 《Cellular and molecular life sciences : CMLS》2007,64(1):50-65
Pelizaeus-Merzbacher disease (PMD) and the allelic spastic paraplegia type 2 (SPG2) arise from mutations in the X-linked gene
encoding myelin proteolipid protein (PLP). Analysis of mutations affecting PLP, the major protein in central nervous system
myelin, has revealed previously unsuspected roles for myelinating glia in maintaining the integrity of the nervous system.
The disease spectrum for PMD and SPG2 is extraordinarily broad and can be best understood by accounting not only for the wide
range of mutations that can occur but also for the effects of PLP1 mutations on both cell autonomous and non-cell autonomous processes in myelinating cells. Appreciating the wide range of
genetic and cellular effects of PLP1 mutations is important for patient and family counseling, understanding disease pathogenesis, and, ultimately, for developing
future disease-specific therapies.
Received 24 April 2006; received after revision 3 July 2006; accepted 9 October 2006 相似文献
998.
Immunophilins: for the love of proteins 总被引:1,自引:0,他引:1
Barik S 《Cellular and molecular life sciences : CMLS》2006,63(24):2889-2900
Immunophilins are chaperones that may also exhibit peptidylprolyl isomerase (PPIase) activity. This review summarizes our
knowledge of the two largest families of immunophilins, namely cyclophilin and FK506-binding protein, and a novel chimeric
dual-family immunophilin, named FK506- and cyclosporin-binding protein (FCBP). The larger members of each family are modular
in nature, consisting of multiple PPIase and/or protein-protein interaction domains. Despite the apparent difference in their
sequence and three-dimensional structure, the three families encode similar enzymatic and biological functions. Recent studies
have revealed that many immunophilins possess a chaperone function independent of PPIase activity. Knockout animal studies
have confirmed multiple essential roles of immunophilins in physiology and development. An immunophilin is indeed a natural
‘protein-philin’ (Greek ‘philin’ = friend) that interacts with proteins to guide their proper folding and assembly.
Received: 7 May 2006; received after revision 3 July 2006; accepted 24 August 2006 相似文献
999.
用原子力显微镜(简称AFM)直接观察、体外表达和体外转录等实验技术组合,观察到了心肌和肝的核DNA片段的基因;用磷酸缓冲液稀释,并用开关蛋白质等活性因子使其部分解离,促使核基因在核DNA片段内或核DNA片段间静态或动态移位,得到了对应核DNA片段中的相关基因,如LDH/DNA体外表达活性变化的LDH同功酶酶谱图。基因静态或动态移位均表达活性降低,且基因移位程度与其对应基因活性降低程度呈正相关性。展示了未来运用AFM和体外表达等实验技术组合研究核DNA片段的基因移位和对应基因突变机制的前景。 相似文献
1000.
为构建小鼠mlrpS-cDNA基因原核、真核表达载体,大肠杆菌表达其融合蛋白。采用反转录-聚合酶链反应从经脂多糖刺激的鼠NIH3T3细胞cDNA中,扩增出编码mlrpS的cDNA。用限制性内切酶KpnⅠand XhoⅠ消化后,插入原核表达载体pTAT中,经酶切鉴定与测序证实后,转化大肠杆菌BL21(DE3)菌株。异丙基β—D硫代半乳糖苷(IPTG)诱导产生融合蛋白。经KpnⅠ和XhoⅠ酶切回收mlrpS-cDNA,插入pcDNA3.1载体中;pcDNA3.1-mlrpS再经KpnⅠ和ApaⅠ酶切后,插入到pEGFP—c1载体上,构建pEGFP-mlrpS融合的真核表达载体。构建mlrpS表达载体经测序证实,与GenBank登录的序列完全一致;双酶切鉴定证实,克隆基因正确插入载体pEGFP及pTAT;SDS—PAGE证实融合蛋白表达成功。说明:成功地构建了mlrpS原核、真核表达载体,成功正确表达了6His/mlrpS融合蛋白。 相似文献