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101.
A case of sclerosing epithelioid fibrosarcoma and its appearance on MRI is presented. The tumor showed a zonal architecture
on MRI with a large central core of very low signal intensity and a peripheral rim of intermediate to high signal intensity
on T1- and T2-weighted spin echo pulse sequences. The core showed decreased cellularity with dense collagen deposition on
histologic examination, and the peripheral zone increased cellularity with increased nuclear atypia. The presence of a prominent
region of very low signal intensity on T1- and T2-weighted images can be seen with neural tumors, giant cell tumor of the
tendon sheath, aggressive fibromatosis, and, in rare instances, with soft tissue sarcomas rich in collagen. 相似文献
102.
急性心肌梗死静脉溶栓后cTnT浓度比值对判断冠脉再通的价值 总被引:1,自引:0,他引:1
目的 探讨血清心肌肌钙蛋白T(cTnT) 3h 2h的浓度比值对急性心肌梗死 (AMI)溶栓后判定冠状动脉再通的价值。方法 采用ELISA法动态检测了 5 7例接受尿激酶静脉溶栓治疗的AMI患者和 31例正常健康对照血清cTnT ,CK MB及CK水平 ,并计算溶栓后 3h与 2h血清cTnT浓度比值。结果 ①cTnT释放呈现两种特征 ,再通组呈双峰型 ,未通组呈单峰型 ,且再通组后期峰值较未通组峰值低 (P <0 .0 1)。②cTnT浓度 3h 2h比值再通组明显高于未通组 (P <0 .0 1) ,以该比值 >1.4 8作为判定再通的标准 ,其对判定冠状动脉再通的敏感性、特异性、预测值分别为 83.3% ,90 .5 % ,93.8%。与峰值时间判定冠脉再通比较差异无显著性 (P >0 .0 5 )。结论 cTnT的动态检测可有效地判定对AMI溶栓后再通与否 ,特别是溶栓后 3h 2h浓度比值 >1.4 8可作为早期判定冠脉再通的标准 ,且具有迅速、省时等优点 ,值得推广应用 相似文献
103.
104.
Richard W. Bowtell Andrew Peters Jonathan C. Sharp Peter Mansfield Edward W. Hsu Nanci Aiken Anthony Horsman Stephen J. Blackband 《Magnetic resonance in medicine》1995,33(6):790-794
NMR microimages of single neural cells were acquired at 500 MHz using a conventional spin echo pulse sequence and a line-narrowing sequence that eliminates susceptibility effects. The data show that any contribution to the measured T2 relaxation rate arising from diffusion in local field inhomogeneities using spin echo sequences at high fields and high spatial resolution is relatively small. We conclude that the measured T2 difference between the nucleus and cytoplasm in these cells represents primarily a true T2 relaxation effect arising from the interactions of water with macromolecules in the two compartments and does not result from microsusceptibility differences. These observations have implications regarding water compartmentation in single cells and the interpretation of the MR characteristics of tissues in vivo. 相似文献
105.
T2毒素在灌流大鼠肠肝中的首过效应和代谢动力学 总被引:3,自引:0,他引:3
建立并用大鼠在体肠-肝灌流标本研究了T2毒素在大鼠肠肝中的首过效应和代谢转化动力学,T2毒素在大鼠肠肝中的主要代谢产物是HT2,3′-OHHT2和其葡萄糖醛酸结合物,T2毒素具有显著的肠肝首过效应,当毒素(42μg·ml~(-1))由上肠系膜动脉恒速单次灌流(8 ml·min~(-1))肠-肝标本时,穗态肝、肠抽提率分别为0.978和0.454,总有效清除率为7.91 ml·min~(-1),T2毒素在循环灌流大鼠肠-肝标本中的消除半衰期为6.5min,主要代谢产物HT2,3′-OHHT2的生成半衰期分别为8.5和38.5 min,结果表明,T2毒素经消化道中毒后,在肠和肝的首过代谢下能很快地转化为产物,因此,毒素在体内的毒效作用主要由其代谢产物表现出来。 相似文献
106.
应用T淋巴细胞亚群单克隆抗体对类固醇治疗前后哮喘患者外周血T淋巴细胞亚群的变化进行检测,结果提示:类固醇治疗后OKT8较治疗前增高,OKT4/OKT8比值较治疗前降低并且接近正常,说明T淋巴细胞是类固醇作用的靶细胞,类固醇可直接影响T细胞亚群分布,发挥其非特异性抗炎作用。 相似文献
107.
Gayle M. Davey Sonya L. Schober Bart T. Endrizzi Angela K. Dutcher Stephen C. Jameson Kristin A. Hogquist 《The Journal of experimental medicine》1998,188(10):1867-1874
During T cell development, thymocytes which are tolerant to self-peptides but reactive to foreign peptides are selected. The current model for thymocyte selection proposes that self-peptide–major histocompatibility complex (MHC) complexes that bind the T cell receptor with low affinity will promote positive selection while those with high affinity will result in negative selection. Upon thymocyte maturation, such low affinity self-peptide–MHC ligands no longer provoke a response, but foreign peptides can incidentally be high affinity ligands and can therefore stimulate T cells. For this model to work, thymocytes must be more sensitive to ligand than mature T cells. Contrary to this expectation, several groups have shown that thymocytes are less responsive than mature T cells to anti-T cell receptor for antigen (TCR)/CD3 mAb stimulation. Additionally, the lower TCR levels on thymocytes, compared with T cells, would potentially correlate with decreased thymocyte sensitivity. Here we compared preselection thymocytes and mature T cells for early activation events in response to peptide–MHC ligands. Remarkably, the preselection thymocytes were more responsive than mature T cells when stimulated with low affinity peptide variants, while both populations responded equally well to the antigenic peptide. This directly demonstrates the increased sensitivity of thymocytes compared with T cells for TCR engagement by peptide–MHC complexes. 相似文献
108.
Sarah E. Townsend Christopher C. Goodnow 《The Journal of experimental medicine》1998,187(10):1611-1621
Antigen-specific B cells are implicated as antigen-presenting cells in memory and tolerance responses because they capture antigens efficiently and localize to T cell zones after antigen capture. It has not been possible, however, to visualize the effect of specific B cells on specific CD4+ helper T cells under physiological conditions. We demonstrate here that rare T cells are activated in vivo by minute quantities of antigen captured by antigen-specific B cells. Antigen-activated B cells are helped under these conditions, whereas antigen-tolerant B cells are killed. The T cells proliferate and then disappear regardless of whether the B cells are activated or tolerant. We show genetically that T cell activation, proliferation, and disappearance can be mediated either by transfer of antigen from antigen-specific B cells to endogenous antigen-presenting cells or by direct B–T cell interactions. These results identify a novel antigen presentation route, and demonstrate that B cell presentation of antigen has profound effects on T cell fate that could not be predicted from in vitro studies. 相似文献
109.
110.
BACKGROUND: We have previously demonstrated that the proteolytic activity of Der p 1 selectively cleaves human CD25, the 55 kDa alpha subunit of the IL-2 receptor. As a result of cleavage of surface CD25, peripheral blood T cells produce less IFN-gamma and more IL-4, thereby leading to progressive polarization of the T cells towards a Th2 cytokine profile. Therefore, these observations underline the potential role of the proteolytic activity of Der p 1 in creating a microenvironment conducive for IgE synthesis. OBJECTIVE: To study the effect of T cells that have been conditioned by the proteolytic activity of Der p 1 on IgE synthesis by B cells. METHODS: We have examined this concept in experiments whereby T cells that have been exposed to either proteolytically active or inactive Der p 1 were cocultured with autologous B cells and IgE antibody synthesis was monitored. RESULTS: Here we demonstrate for the first time that coculturing T cells that have been in contact with proteolytically active Der p 1 with autologous B cells leads to augmentation of IgE antibody responses. CONCLUSIONS: The proteolytic activity of Der p 1 conditions human T cells, which then become empowered to trigger enhanced IgE synthesis by B cells. 相似文献