全文获取类型
收费全文 | 16125篇 |
免费 | 1278篇 |
国内免费 | 918篇 |
专业分类
耳鼻咽喉 | 72篇 |
儿科学 | 105篇 |
妇产科学 | 109篇 |
基础医学 | 3099篇 |
口腔科学 | 193篇 |
临床医学 | 633篇 |
内科学 | 1753篇 |
皮肤病学 | 207篇 |
神经病学 | 1634篇 |
特种医学 | 332篇 |
外国民族医学 | 5篇 |
外科学 | 660篇 |
综合类 | 4110篇 |
现状与发展 | 4篇 |
预防医学 | 633篇 |
眼科学 | 174篇 |
药学 | 2325篇 |
中国医学 | 1223篇 |
肿瘤学 | 1050篇 |
出版年
2023年 | 87篇 |
2022年 | 147篇 |
2021年 | 260篇 |
2020年 | 303篇 |
2019年 | 275篇 |
2018年 | 267篇 |
2017年 | 427篇 |
2016年 | 441篇 |
2015年 | 521篇 |
2014年 | 764篇 |
2013年 | 1001篇 |
2012年 | 946篇 |
2011年 | 1095篇 |
2010年 | 889篇 |
2009年 | 814篇 |
2008年 | 917篇 |
2007年 | 919篇 |
2006年 | 910篇 |
2005年 | 744篇 |
2004年 | 731篇 |
2003年 | 660篇 |
2002年 | 576篇 |
2001年 | 478篇 |
2000年 | 439篇 |
1999年 | 390篇 |
1998年 | 289篇 |
1997年 | 261篇 |
1996年 | 290篇 |
1995年 | 263篇 |
1994年 | 239篇 |
1993年 | 239篇 |
1992年 | 202篇 |
1991年 | 153篇 |
1990年 | 148篇 |
1989年 | 125篇 |
1988年 | 124篇 |
1987年 | 105篇 |
1986年 | 92篇 |
1985年 | 126篇 |
1984年 | 122篇 |
1983年 | 54篇 |
1982年 | 93篇 |
1981年 | 92篇 |
1980年 | 61篇 |
1979年 | 42篇 |
1978年 | 40篇 |
1977年 | 34篇 |
1976年 | 31篇 |
1975年 | 15篇 |
1970年 | 21篇 |
排序方式: 共有10000条查询结果,搜索用时 218 毫秒
81.
The protective effect of affinity purified antigen has been investigated in an experimental model for malaria which shows a well marked recrudescence of parasitaemia, a feature of the disease in man. A monoclonal antibody (MoAb) recognizing an epitope common to two genetically distinct cloned lines of Plasmodium chabaudi (AS and CB), was used to purify a Mr250,000 polymorphic schizont antigen (PSA) from these parasites. The purified preparations were then examined for the presence of specific and cross-reactive epitopes by immunoprecipitation with a panel of MoAb raised against P. chabaudi AS. When tested previously on smears of parasitized blood by immunofluorescence, or against lysates of parasitized erythrocytes by immunoprecipitation, most of these MoAb had been found to be AS specific. When either AS or CB affinity purified Mr250,000 PSA was used as the target, these same MoAb immunoprecipitated both antigens, and in some cases, a number of associated polypeptides (AP) which copurify with the Mr250,000 PSA. Subsequently, mice were immunized with either the purified AS or CB antigens in Freund's complete adjuvant (FCA). Prechallenge sera were compared by indirect immunofluorescence and immunoprecipitation. Sera from mice immunized with AS antigen reacted strongly with AS and cross-reacted with CB parasite preparations. Pre-challenge serum from CB antigen immunized mice reacted well with CB, but only faintly with AS preparations. In mice immunized with the AS antigen and then challenged with either AS or CB parasites, the initial parasitaemias were delayed in appearance and the height of the peak parasitaemia reduced, an effect which was most pronounced after challenge with homologous parasites. Only homologous challenge of the mice immunized with CB antigen produced statistically significant modification of the initial parasitaemia. In the immunized mice challenged with homologous parasites, the delayed appearance and slightly reduced peak of the primary parasitaemia was associated with delayed resolution of the patent parasitaemia and significant enhancement of the recrudescence. 相似文献
82.
C_3基因在BXSB小鼠主要脏器中的表达 总被引:1,自引:1,他引:0
用同位素标记cDNA探针的分子杂交方法检测了BXSB小鼠肝、肾、脾、胸腺各脏器中补体C_3mRNA的表达情况,结果表明3~4月龄雄性BXSB小鼠肝、肾、脾各脏器C_3mRNA的表达量较正常对照鼠显著增加。C_3基因的过度表达可能参与BXSB小鼠SLE多脏器非感染性炎症的发生,同时提示该鼠存在M系统的大量扩增及活化。 相似文献
83.
Distraction osteogenesis in the Cbfa-1+/- mouse. 总被引:2,自引:0,他引:2
S Isefuku C J Joyner A A C Reed A H R W Simpson 《Journal of orthopaedic research》2004,22(6):1276-1282
84.
CpG ODN增强乙肝疫苗在老年小鼠中的免疫应答 总被引:2,自引:0,他引:2
目的:探讨CpG ODN对老年小鼠的体液和细胞免疫应答的增强作用。方法:选用老年C57BL/6小鼠,将乙肝疫苗和10μg、20μg CpG ODN同时或单独肌注到小鼠体内,两周后以同样剂量加强免疫一次,再过3周后摘除眼球取血,用EILSA方法检测抗HBs16;抗体和IL-12;无菌取脾脏作HE染色,观察脾脏淋巴细胞变化。结果:10μg和20μg CpG ODN与疫苗同时注射组产生的抗体绝对量分别是单独注射疫苗组的3倍和4倍;产生的IL-12水平较对照组有明显升高,且20μg比10μCpG组产生的IL-12水平更高。光镜下各组的脾脏淋巴细胞的变化如下:正常老年鼠组脾脏淋巴细胞较正常青年鼠组明显稀少;老年鼠 10μgCpG组脾脏淋巴细胞较正常老年鼠组有了明显增加,且细胞核也明显增大;20μgCpG组增加的更加明显。结论:CpG ODN能增强乙肝疫苗在老年小鼠中的体液和细胞免疫应答。 相似文献
85.
灵芝多糖对小鼠糖耐量的影响 总被引:5,自引:0,他引:5
目的 :探讨灵芝多糖对正常和糖尿病小鼠糖耐量的影响。方法 :采用腹腔注射四氧嘧啶 (2 0 0 mg· kg- 1 )诱导小鼠造成糖尿病模型 ,分别观察单次给予 0 .5 g·kg- 1、1.5 g· kg- 1灵芝多糖后 ,正常和糖尿病小鼠糖耐量的改变。结果 :灵芝多糖 0 .5 g· kg- 1仅能显著降低糖尿病小鼠餐后 1h和 2 h血糖 ,而灵芝多糖 1.5 g·kg- 1对正常和糖尿病小鼠餐后 1h和 2 h血糖均有显著降低作用。结论 :灵芝多糖能改善正常和四氧嘧啶糖尿病小鼠糖耐量。 相似文献
86.
87.
Clonal deletion and anergy are two major mechanisms of self-tolerance. However, the molecular mechanisms underlying clonal deletion and anergy, as well as the threshold of TCR affinity/avidity required for these processes, are not known. Expression of the V beta 8.1 TCR correlates with the reactivity of the T cells to the minor lymphocyte stimulating locus-1a (Mls-1a) and T cells expressing this TCR are deleted in the thymus of Mls-1a mice. Similarly, in TCR V beta 8.1 transgenic mice, the number of CD4+CD8-T cells is reduced in Mls-1a mice. However, small numbers of CD4+CD8-T cells remain in the periphery of adult Mls-1a transgenic mice. We have generated T cell clones from TCR V beta 8.1 transgenic mice by stimulation of lymph node T cells with C57BL/6 alloantigens. Interestingly, CD4+CD8-V beta 8.1+ clones isolated from the transgenic mice of Mls-1a background responded to the self-antigen Mls-1a, to which they did not respond in primary assay. Reactive patterns of the clones were compared with clones derived from Mls-1b mice. Proliferation and cytokine production of the clones from Mls-1a mice to the self-antigen Mls-1a were generally reduced when compared with clones from Mls-1b mice. More importantly, T cell clones from Mls-1a mice required more Mls-1a antigen for their activation, and were more susceptible to the inhibitory effects of anti-CD4 antibody on the proliferative responses to Mls-1a than those from Mls-1b mice. These results suggest that the T cell receptor on clones derived from Mls-1a mice have functional but reduced affinity/avidity for self-antigen Mls-1a. 相似文献
88.
应用小鼠骨髓细胞长周期培养(LTBMC)体系,观察重组人白细胞介素-1α(rhIL-1α)对造血细胞增殖的影响。结果显示,经rhlL-1α作用后,小鼠LTBMC中悬浮细胞数增多,其中粒单系祖细胞(CFU-GM)数量也明显增加,维持时间延长。表明rhIL-1α能促进小鼠造血细胞在体外LTBMC中增殖并分化,而且与剂量有关系。rhIL-1α加入的时间,以骨髓细胞2次接种时同时加入为好,延迟加入则作用减弱。本实验对骨髓干、祖细胞体外扩增和自体骨髓移植等方面的研究有一定意义。 相似文献
89.
90.
本文对新型有机磷农药,25%乙基硫环磷进行了Ames及微核两项诱变性试验研究。Ames试验中,无论是否加入S9活化系统,25%乙基硫环磷均未能诱发回变菌落数的增加;微核试验的各剂量组PCE微核率也较低,(2‰~3‰),与阴性对照相比无显著性差异。 相似文献