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排序方式: 共有164条查询结果,搜索用时 386 毫秒
111.
A chlorinated withanolide, 6α-chloro-5β,17α-dihydroxywithaferin A (1), and nine known withanolides, 6α-chloro-5β-hydroxywithaferin A (2), (22R)-5β-formyl-6β,27-dihydroxy-1-oxo-4-norwith-24-enolide, withaferin A, 2,3-dihydrowithaferin A, 3-methoxy-2,3-dihydrowithaferin A, 2,3-didehydrosomnifericin, withanone, withanoside IV and withanoside X, were isolated from Withania somnifera (Solanaceae). All structures were elucidated on the basis of spectroscopic methods (IR, HRESIMS, 1D/2D NMR). X-ray crystallography confirmed the absolute configuration of 1. 相似文献
112.
113.
Xin Li Shiyan Chen Weili Hu Shuaike Shi Wei Shen Xiang Zhang Huaping Wang 《Carbohydrate polymers》2009,76(4):509-512
CdS nanoparticles have been synthesized and stabilized on unique bacterial cellulose (BC) nanofibers in situ. The obtained nanocomposite material have been characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), fourier transformed infrared (FTIR), thermogravimetric analysis (TGA), ultraviolet–visible (UV–Vis) and photoluminescence (PL) spectroscopy. The results indicated that CdS nanoparticles of about 30 nm diameter deposited on BC nanofibres are well-dispersed in the BC nanofibre-network and the uniform spherical CdS nanoparticles are comprised of nano-sized CdS crystal. Moreover, the crystallite sizes of CdS crystals are about 8 nm. The nanocomposites would have potential application as photocatalyst, novel luminescence and photoelectron transfer devices. 相似文献
114.
利用RNA干扰技术构建PYGO1基因RNA干扰(RNAi)的真核表达质粒(pSUPER-PYGO1)。首先,针对PYGO1 cDNA序列设计并化学合成一对编码短发夹RNA序列,经退火插入到由BglⅡ和XhoⅠ酶切的pSU-PER质粒上构建重组RNAi质粒pSUPER-PYGO1。通过XbaⅠ酶切鉴定及测序分析验证构建效果,将正确构建的质粒转染大鼠心肌细胞系H9c2建立产生逆转录病毒的细胞克隆。通过RT-PCR和Western blot检测pSU-PER-PYGO1对H9c2细胞中PYGO1 mRNA和PYGO1蛋白的干扰效果。pSUPER-PYGO1质粒经酶切鉴定及测序分析,发现59nt寡核苷酸成功插入到预计位点,且序列完全一致;RT-PCR和Western blot检测结果显示转染pSUPER-PYGO1的细胞中PYGO1 mRNA和PYGO1蛋白量明显降低。因此,靶向PYGO1的pSUPER RNAi载体构建成功,为进一步从分子水平探讨PYGO1在心脏发育中的功能奠定了基础。 相似文献
115.
Martin JL Bluhm WF He H Mestril R Dillmann WH 《American journal of physiology. Heart and circulatory physiology》2002,283(1):H85-H91
High levels of alpha B-crystallin are present in the cardiomyocyte, yet little is understood about the function and importance of this protein. Like many other small heat shock proteins, alpha B-crystallin forms large oligomeric complexes whose size can be regulated by posttranslational modifications. The size of these complexes can modify the function of the protein. A naturally occurring COOH-terminal mutant has many detrimental effects in the lens of the eye and altered oligomerization. Therefore, we mutated the two COOH-terminal lysines of alpha B-crystallin to glycines (K174/175G) and adenovirally mounted them to transduce cardiomyocytes. We analyzed the effect of this mutation on oligomerization, microtubular stabilization, and ischemic outcome. A nearly 45% downward shift in complex size was observed with the mutant by native PAGE followed by immunoblotting. The overexpressed protein no longer protected the tubulin cytoskeleton against ischemic stress by confocal analysis. The mutant caused a 30% increase in cytosolic enzyme release with ischemia compared with control, whereas a 33% decrease was associated with wild-type alpha B-crystallin overexpression. We conclude that the COOH terminus of alpha B-crystallin is crucial to its proper function. 相似文献
116.
Liu L Benten WP Wang L Hao X Li Q Zhang H Guo D Wang Y Wunderlich F Qiao Z 《Steroids》2005,70(9):604-614
Androgens can increase susceptibility toward numerous parasitic infections as well as modulate apoptosis of immune cells. According to the current view, androgens mediate immune cell activities not only through classical intracellular androgen receptors (AR), but also through membrane receptors on the cell surface. Here, using murine bone marrow-derived macrophages (BMMs), we examined the influence of testosterone on Leishmania donovani infection and cell viability in vitro as well as the possible mechanisms. Our data demonstrated that testosterone directly increased intramacrophage infection by L. donovani. In addition, testosterone decreased cell viability by way of apoptosis, accompanied by increased Fas, FasL, and Caspase-8 expression. However, these effects of testosterone could not be associated with the classical AR in BMMs since AR was not detectable using different experimental techniques. Instead, it was found that testosterone could bind to the surface of BMMs by the use of an impermeable testosterone-BSA-FITC in confocal laser scanning microscopy and flow cytometry. Collectively, our data indicated that the influence of testosterone on L. donovani infection and viability of BMMs was mediated through the binding sites of testosterone on cell surfaces, which provided a novel mode of direct action of testosterone on AR-free BMMs. 相似文献
117.
Pochapsky TC Pochapsky SS Ju T Mo H Al-Mjeni F Maroney MJ 《Nature structural biology》2002,9(12):966-972
Here we report the structure of acireductone dioxygenase (ARD), the first determined for a new family of metalloenzymes. ARD represents a branch point in the methionine salvage pathway leading from methylthioadenosine to methionine and has been shown to catalyze different reactions depending on the type of metal ion bound in the active site. The solution structure of nickel-containing ARD (Ni-ARD) was determined using NMR methods. X-ray absorption spectroscopy, assignment of hyperfine shifted NMR resonances and conserved domain homology were used to model the metal-binding site because of the paramagnetism of the bound Ni2+. Although there is no structure in the Protein Data Bank within 3 A r.m.s deviation of that of Ni-ARD, the enzyme active site is located in a conserved double-stranded b-helix domain. Furthermore, the proposed Ni-ARD active site shows significant post-facto structural homology to the active sites of several metalloenzymes in the cupin superfamily. 相似文献
118.
错配碱基套式PCR-RFLP检测K-ras癌基因第12位密码子点突变,并与一步法PCR-RFLP作比较.结果显示套式PCR-RFLP可检测出500细胞中的一个突变细胞,比一步法PCR-RFLP分析的敏感性提高了100倍.利用该方法检测纤维支气管镜收集的标本中的突变细胞,结果发现9例肺腺癌中有5例发生了K-ras癌基因第12位密码子点突变.提示该方法可行,值得推广应用. 相似文献
119.
人参茎叶皂甙对创伤小鼠活化T细胞内磷脂酰肌醇代谢的影响 总被引:1,自引:0,他引:1
研究了人参茎叶皂甙(GSL)对创伤小鼠活化T细胞内磷脂酰肌醇代谢的影响。结果显示,GSL体内应用(50mg·kg ̄(-1)·d ̄(-1),伤后0─3d)对创伤小鼠活化T细胞内三磷酸肌醇(IP_3)、游离Ca ̄(2+)、钙调素(CaM)、CaM依赖的蛋白激酶(CaM-Pk)、蛋白激酶C(PKC)水平的降低具有明显的逆转效应,并可明显降低创伤小鼠血清、巨噬细胞、Ts细胞对各指标的抑制活性。GSL(1.0─100mg/L)在体外也可明显提高创伤小鼠活化T细胞内IP_3、Ca ̄(2+)、CaM、CaM-PK及PKC水平。上述结果表明,GSL可逆转创伤小鼠活化T细胞内磷脂酰肌醇代谢的降低。 相似文献
120.
Jingru Zhao Xiang Yu Miao Zhu Huaping Kang Jinbiao Ma Min Wu Jianhua Gan Xin Deng Haihua Liang 《PLoS biology》2016,14(4)
Although quorum-sensing (QS) systems are important regulators of virulence gene expression in the opportunistic human pathogen Pseudomonas aeruginosa, their detailed regulatory mechanisms have not been fully characterized. Here, we show that deletion of PA2588 resulted in increased production of pyocyanin and biofilm, as well as enhanced pathogenicity in a mouse model. To gain insights into the function of PA2588, we performed a ChIP-seq assay and identified 28 targets of PA2588, including the intergenic region between PA2588 and pqsH, which encodes the key synthase of Pseudomonas quinolone signal (PQS). Though the C-terminal domain was similar to DNA-binding regions of other AraC family members, structural studies revealed that PA2588 has a novel fold at the N-terminal region (NTR), and its C-terminal HTH (helix-turn-helix) domain is also unique in DNA recognition. We also demonstrated that the adaptor protein ClpS, an essential regulator of ATP-dependent protease ClpAP, directly interacted with PA2588 before delivering CdpR to ClpAP for degradation. We named PA2588 as CdpR (ClpAP-degradation and pathogenicity Regulator). Moreover, deletion of clpP or clpS/clpA promotes bacterial survival in a mouse model of acute pneumonia infection. Taken together, this study uncovered that CdpR is an important QS regulator, which can interact with the ClpAS-P system to regulate the expression of virulence factors and pathogenicity. 相似文献