全文获取类型
收费全文 | 12514篇 |
免费 | 1016篇 |
国内免费 | 410篇 |
专业分类
耳鼻咽喉 | 107篇 |
儿科学 | 271篇 |
妇产科学 | 91篇 |
基础医学 | 3986篇 |
口腔科学 | 296篇 |
临床医学 | 725篇 |
内科学 | 2404篇 |
皮肤病学 | 187篇 |
神经病学 | 259篇 |
特种医学 | 153篇 |
外国民族医学 | 1篇 |
外科学 | 601篇 |
综合类 | 1414篇 |
现状与发展 | 8篇 |
预防医学 | 1339篇 |
眼科学 | 66篇 |
药学 | 730篇 |
2篇 | |
中国医学 | 576篇 |
肿瘤学 | 724篇 |
出版年
2024年 | 25篇 |
2023年 | 259篇 |
2022年 | 301篇 |
2021年 | 634篇 |
2020年 | 431篇 |
2019年 | 350篇 |
2018年 | 372篇 |
2017年 | 421篇 |
2016年 | 447篇 |
2015年 | 506篇 |
2014年 | 733篇 |
2013年 | 910篇 |
2012年 | 636篇 |
2011年 | 742篇 |
2010年 | 618篇 |
2009年 | 657篇 |
2008年 | 562篇 |
2007年 | 593篇 |
2006年 | 535篇 |
2005年 | 481篇 |
2004年 | 472篇 |
2003年 | 356篇 |
2002年 | 314篇 |
2001年 | 304篇 |
2000年 | 222篇 |
1999年 | 219篇 |
1998年 | 180篇 |
1997年 | 167篇 |
1996年 | 151篇 |
1995年 | 123篇 |
1994年 | 133篇 |
1993年 | 110篇 |
1992年 | 94篇 |
1991年 | 86篇 |
1990年 | 74篇 |
1989年 | 81篇 |
1988年 | 75篇 |
1987年 | 60篇 |
1986年 | 60篇 |
1985年 | 73篇 |
1984年 | 60篇 |
1983年 | 37篇 |
1982年 | 58篇 |
1981年 | 41篇 |
1980年 | 45篇 |
1979年 | 34篇 |
1978年 | 23篇 |
1977年 | 22篇 |
1976年 | 30篇 |
1975年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
71.
为研究分娩方式是否影响新生儿免疫状态,检测和比较了68例妊娠足月阴道产和64例妊娠足月部宫产分娩的新生儿脐血C3、C4及IgG、IgA、IgM的含量,其结果:IgG的的含量阴产组明显高于剖宫产组,且男婴阴道产组IgG的信明显高于剖宫产。说明剖宫产可参降低新生儿免疫应签及抗感染能力。 相似文献
72.
粉被虫草提取物对巨噬细胞吞噬功能及CTL活性的影响 总被引:2,自引:0,他引:2
研究粉被虫草菌丝体提取物在体外对小鼠腹腔巨噬细胞吞噬功能和脾细胞免疫功能的影响,结果表明:粉被虫草提取物在正常情况下不仅能够促进小鼠腹腔巨噬细胞的吞噬功能,而在免疫抑制的情况下,一定浓度的粉被虫草菌丝体提取物还能恢复提高吞噬功能;它不仅能促进正常脾活化T细胞的增殖,而且能恢复环磷酰胺和氢化可的松抑制免疫小鼠脾活化T细胞的增殖;在较高浓度下能增高小鼠脾细胞毒T淋巴细胞(CTL)活性,同时在一定浓度下能恢复免疫抑制小鼠脾CTL活性。 相似文献
73.
Low numbers of parasites from cloned lines of the rodent malaria parasites, Plasmodium chabaudi chabaudi AS and P. yoelii yoelii A, injected into CBA/Ca mice produce acute but usually self-limiting infections. During crisis, i.e. 1-2 days after peak parasitaemia, 'pre-immune' mice experiencing such 'background' infections were reinfected intravenously with homologous parasites or parasites of heterologous strains or species. P. c. chabaudi AS pre-immune mice controlled an AS challenge with essentially the same kinetics as the background infection. Reinfection of AS pre-immune mice with the heterologous (CB and IP-PCI) P. c. chabaudi strains or P. chabaudi adami DS had little effect on the initial growth of these parasites, although eventually the parasitaemia was controlled. In contrast, a partial inhibitory effect on the growth of P. vinckei lentum DS was evident. Challenge with the non-lethal (A) or lethal (YM) variants of P. y. yoelii resulted in an increase in both the growth and virulence of these parasites. P. y. yoelii A pre-immune mice controlled a homologous challenge, but were less effective at controlling the YM variant. In addition, they were unable to clear rapidly a P. c. chabaudi AS or P. v. lentum DS challenge. Both the multiplication and virulence of P. berghei ANKA were enhanced. These findings demonstrate that resolution of the primary acute parasitaemia in P. c. chabaudi AS- and P. y. yoelii A-infected mice is predominantly mediated by species- and strain-specific mechanisms. 相似文献
74.
益气补肾汤对小鼠免疫功能的影响 总被引:1,自引:0,他引:1
目的 :研究益气补肾汤对小鼠免疫功能的影响。方法 :用药理实验的方法 ,将小鼠制成免疫抑制模型 ,灌服益气补肾汤 ,观察和测定小鼠巨噬细胞吞噬功能 ,胸腺、脾指数 ,迟发性超敏反应及溶血素抗体水平。结果 :灌服益气补肾汤的小鼠与灌服蒸馏水的免疫抑制模型小鼠相比 ,巨噬细胞吞噬能力增强 (P <0 .0 5 ) ,胸腺指数升高(P <0 .0 5 ) ,迟发性超敏反应增强 (P <0 .0 5 ) ,且血清溶血素抗体升高 ,脾指数 2组间差异无统计学意义。结论 :益气补肾汤可增强机体免疫功能 相似文献
75.
Vaccination of mice with attenuated S. japonicum cercariae induces protection against secondary infection which can be transferred to naive mice with serum (VMS). The presence of antibody does not per se impart protection as serum from mice carrying non-attenuated infections (CIS), contains high levels of specific antibody, but confers no protection. Here we describe the increased protection transferred (20 to 68%) with increased number of vaccinations (one to five) given to the donors, and its decline with time after the final vaccination. We also describe the development of IgM, IgA, IgE, total IgG and IgG subclass responses in VMS, giving different levels of protection and CIS, directed against sodium periodate-sensitive and -resistant epitopes in ‘skin-stage’, ‘lung-stage’and ‘liver-stage’schistosomula, adult worms and eggs. In addition, antibody affinity maturation, development of S. japonicum species-specific responses, and vaccination-specific responses were examined. No response developed in parallel with serum-mediated immunity, suggesting immunity may be due to responses against individual antigens. Preliminary examination of antigens recognized in Western blot showed that two schistosomal membrane antigens, of 13 and 40 kDa, were recognized by VMS from mice vaccinated five times (68% protection), but not by twice vaccinated VMS (27% protection). Neither antigen was recognized by non-protective CIS. 相似文献
76.
中老年人膳食和体液免疫水平的调查 总被引:1,自引:0,他引:1
作者调查了161例(男:98,女:63)中老年人的营养素摄入量、血浆蛋白及体液免疫水平。结果:该人群的大部分人热能的摄入量达RDA值;膳食蛋白质、维生素A、B2、C、锌和铁的摄入量较低;脂肪摄入量按热能比高于30%者约占30%;血浆总蛋白、球蛋白水平较低,尤其是女性;免疫球蛋白IgA偏低,IgG和IgM偏高。 相似文献
77.
维生素E对烧伤小鼠免疫功能改善及其机制 总被引:7,自引:0,他引:7
本实验研究了维生素E(VE)改善烧伤后免疫功能的作用,并对其作用机制进行了探讨。结果显示,小鼠11%~12%总体表面积(TBSA)全层皮肤烧伤后血、肝、脾中过氧化脂质(LPO)水平升高、谷胱甘肽(GSH)含量下降,淋巴细胞增殖反应、白介素一2(IL一2)生成、空斑形成细胞(IJFC)形成及迟发型超敏反应(DTH)均处于抑制状态。投予VE后可防止烧伤动物体内LPO水平、GSH含量明显变化,免疫功能受抑制的程度也明显小于未投予组。以超氧化物歧化酶(SOD)处理的作用与VE相同。体外实验显示,过氧化亚油酸可抑制淋巴细胞增殖反应以及IL一2产生、诱发淋巴细胞脂质过氧化、降低淋巴细胞内GSH含量。淋巴细胞上述功能的抑制与LPO水平密切相关;加入VE可抑制过氧化亚油酸对淋巴细胞的上述作用。提示VE可改善烧伤后免疫功能,其机制可能是通过抗氧化作用而发挥的。 相似文献
78.
Jens Jordan 《Clinical autonomic research》2007,17(6):331-333
Genes influencing the autonomic nervous system continue as a focus of research. Recent publications applied different methods
to identify genes influencing autonomic cardiovascular regulation in humans. Two reports relied on a candidate gene approach.
Common genetic polymorphisms in the promoter region of the tyrosine hydroxylase gene were shown to influence catecholamine
synthesis and blood pressure. The same group tested the hypothesis that the GTP cyclohydrolase 1 (GCH1) gene influences catecholamine
excretion and cardiovascular regulation. GCH1 affects tyrosine hydroxylase function indirectly. The authors concluded that
the GCH1 gene may influence cardiovascular autonomic regulation through changes in nitric oxide production rather than a change
in tyrosine hydroxylase activity. The third genetic study used a single nucleotide polymorphism chip to analyze 100,000 genetic
polymorphisms scattered throughout the genome in participants of the Framingham study. The authors identified several polymorphisms
that may influence QT interval duration, heart rate, and heart rate variability. The respective genes have not been identified
with certainty. Another study suggested that catecholamines may be released from phagocytes and regulate pulmonary inflammation
through alpha-2 adrenoreceptor activation in an autocrine or paracrine fashion. 相似文献
79.
对1997年以来423例病态喉的频闪喉镜表现进行分析,结果显示声带有病理改变者其粘膜波、振幅、闭合相、运动周期性、对称性均有不同程度的变化,这种变化能直接反映声带病变的深度及范围,对喉部疾病的诊断、鉴别诊断、治疗指导及预后评价具有重要意义. 相似文献
80.
Changes in activity of some mechanisms of specific and nonspecific immunity in vitamin B1 deficiency
A. D. Pletsityi 《Bulletin of experimental biology and medicine》1979,88(1):741-743
The effect of thiamine deficiency on the immune response and activity of certain mechanisms of natural immunity was studied in adult rats. Thiamine deficiency was simulated experimentally by a single injection of hydroxythiamine, a vitamin B1 antagonist. Administration of hydroxythiamine caused a marked decrease in complement activity, phagocytic activity of the peripheral blood leukocytes, bactericidal activity of the serum, and antibody production in response to immunization with sheep's red blood cells. Conversely, lysozyme activity increased. In vitamin B1 deficiency the intensity of incorporation of [14C]leucine into liver protein synthesis was reduced.Department of Pathological Physiology, N. I. Sechenov First Moscow Medical Institute. (Presented by Academician of the Academy of Medical Sciences of the USSR G. V. Vygodchikov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 88, No. 7, pp. 60–62, July, 1979. 相似文献