全文获取类型
收费全文 | 61925篇 |
免费 | 4402篇 |
国内免费 | 2955篇 |
专业分类
耳鼻咽喉 | 173篇 |
儿科学 | 1011篇 |
妇产科学 | 628篇 |
基础医学 | 8689篇 |
口腔科学 | 521篇 |
临床医学 | 4930篇 |
内科学 | 18593篇 |
皮肤病学 | 652篇 |
神经病学 | 3189篇 |
特种医学 | 1035篇 |
外国民族医学 | 2篇 |
外科学 | 4219篇 |
综合类 | 7592篇 |
现状与发展 | 5篇 |
预防医学 | 5969篇 |
眼科学 | 880篇 |
药学 | 7120篇 |
15篇 | |
中国医学 | 1802篇 |
肿瘤学 | 2257篇 |
出版年
2023年 | 567篇 |
2022年 | 1205篇 |
2021年 | 1547篇 |
2020年 | 1476篇 |
2019年 | 2115篇 |
2018年 | 2091篇 |
2017年 | 1892篇 |
2016年 | 2016篇 |
2015年 | 2273篇 |
2014年 | 3814篇 |
2013年 | 4154篇 |
2012年 | 3664篇 |
2011年 | 4113篇 |
2010年 | 3259篇 |
2009年 | 3130篇 |
2008年 | 2974篇 |
2007年 | 3332篇 |
2006年 | 2888篇 |
2005年 | 2605篇 |
2004年 | 2117篇 |
2003年 | 1908篇 |
2002年 | 1667篇 |
2001年 | 1467篇 |
2000年 | 1233篇 |
1999年 | 1147篇 |
1998年 | 926篇 |
1997年 | 956篇 |
1996年 | 672篇 |
1995年 | 712篇 |
1994年 | 620篇 |
1993年 | 439篇 |
1992年 | 397篇 |
1991年 | 304篇 |
1990年 | 253篇 |
1989年 | 230篇 |
1988年 | 198篇 |
1987年 | 171篇 |
1985年 | 494篇 |
1984年 | 581篇 |
1983年 | 462篇 |
1982年 | 425篇 |
1981年 | 416篇 |
1980年 | 370篇 |
1979年 | 333篇 |
1978年 | 284篇 |
1977年 | 214篇 |
1976年 | 252篇 |
1975年 | 251篇 |
1974年 | 201篇 |
1973年 | 177篇 |
排序方式: 共有10000条查询结果,搜索用时 1 毫秒
101.
Behcet's disease (BD) is characterized by recurrent oral aphthae, skin lesions, eye lesions, and genital ulceration. To determine the pathogenesis of BD, we performed histological and immunohistochemical studies of these mucocutaneous lesions, an assay of neutrophil activity, and HLA typing. Dense dermal or subcutaneous infiltrations of polymorphonuclear cells (PMN) without leukocytoclastic vasculitis were found in 28 of 57 lesions. Immunohistochemically, deposits of C3 on the vessels were found in 12 of 31 lesions. Deposits of immunoglobulin were not found except for one of IgM. C3 deposits and PMN infiltrations were significantly related (p<0.05). PMN activity by polarization was enhanced; however, the results did not show a significant relationship with the PMN infiltrations or the C3 deposits. The incidence of HLA-B51 was significantly high in BD, but no significant relationship was found between HLA-B51 and the results of other examinations. These results suggest that the pathogenesis of BD lesions differs from that of collagen diseases and that C3 deposits on the vessels may play an important role in the development of mucocutaneous lesions where PMN have mainly infiltrated. 相似文献
102.
Our new finding of de novo synthesis and secretion of C3 by both murine peritoneal macrophages and polymorphonuclear leukocytes (PMN) was confirmed by the incorporation of [35S]methionine into C3 molecules and their complete inhibition by cycloheximide. The methods of secretion of C3 from these two types of cells were compared by examining the C3 contents in their culture supernatants. Completely different modes of secretion were observed, i.e. although macrophages synthesize and secrete C3 constitutively, PMN has a mechanism to store the already synthesized C3 in the cell and secrete it in response to stimuli. Protein kinase C (PKC) activators, e.g. 12-O-tetradecanoyl-phorbol 13-acetate, dioctanoyl glycerol, and mezerein, as well as calcium ionophore A23187 stimulate the secretion of C3 from PMN. These results suggest the involvement of PKC and the calmodulin pathway. A very sensitive method for measuring C3 activity was developed which enabled us to show for the first time that C3 secreted by PMN had opsonizing activity and that particles cultured with PMN were phagocytosed effectively. 相似文献
103.
本文采用热变性温度法和液相复性速率法对—轻型特征及血清学反应相似米克戴德军团菌(Lm)的菌株进行了测定,结果表明该菌与标准Lm(C DC株)的DNA G Cmol%相差3.45%,与标准Lm(C DC株)的DNA同源性达81.99%,根据伯杰细菌鉴定手册(1984),可判定该菌株与标准Lm(C DC株)为遗传型一致的类群,即从遗传学角度证明该菌为Lm。 相似文献
104.
运用巢式聚合酶链反应(PCR)等方法检测了5例丙型肝炎病毒核糖核酸(HCV—RNA)阳性患者的肝癌、癌旁组织和周围血清中HCV—RNA正链和负链,其中男4例,女1例。结果,正链检测:血清及癌旁组织全部阳性,癌组织中3例阳性。负链检测:血清中均阴性,癌组织3例阳性,癌旁组织5例均阳性。本组5例患者肝脏HCV—RNA负链阳性,推测HCV以HCV—RNA负链作为模板在感染的肝脏组织中复制,HCV持续存在于肝脏组织中对肝癌的发生起了一定的作用。 相似文献
105.
中国人不同C4基因型时血中C4浓度的定量检测 总被引:1,自引:0,他引:1
用神经氨酸酶及羧肽酶B处理血浆,依次经C4高压琼脂糖电泳、免疫固定、薄层激光扫描等步骤,并结合血浆免疫火箭电泳定量法对我国武汉地区随机人群的血浆C4总量及C4两种同种型,主要别型,单、双QO,重复座位等时的血浆C4含量进行了检测与分析。结果发现:遗传因素明显影响血浆C4水平,因而在群体中表现宽广的C4浓度范围,特别在有C4QO与C4重复基因座位时差异特别明显。这一研究提示,不同的C4基因型,循环C4含量表现明显差异。临床上检测C4含量时应该考虑患者的C4基因型别。 相似文献
106.
丙型肝炎患者外周血单核细胞中丙型肝炎病毒复制的研究 总被引:2,自引:0,他引:2
9例临床诊断为丙型肝炎患者,研究其外周血单核细胞中HCVRNA的存在及复制。9例患者血清标本抗-HCV及HCVRNA均为阳性,采用高敏感的逆转录一套式PCR法测定其外周血单核细胞中HCV正、负链RNA,结果9例患者外周血单核细胞中7例HCV正链RNA阳性,3例HCV负链RNA阳性,证实部分丙肝患者外周血单核细胞中存在HCV的复制,表明肝细胞并非为HCV感染与复制的唯一场所。 相似文献
107.
Nerve biopsy findings in Niemann-Pick type II (NPC) 总被引:1,自引:0,他引:1
A. F. Hahn J. J. Gilbert C. Kwarciak J. Gillett C. F. Bolton C. A. Rupar J. W. Callahan 《Acta neuropathologica》1994,87(2):149-154
The severe infantile form of Niemann-Pick disease type II was diagnosed in a 4-year-old girl and confirmed by demonstrating in cultured skin fibroblasts a deficiency of low-density lipoprotein-stimulated cholesterol ester synthesis of < 5% of normal. Electrodiagnostic studies revealed changes of a predominantly demyelinating motor and sensory polyneuropathy. Light microscope and ultrastructural examination of a peroneal nerve biopsy showed unique changes. Compacted myelin sheaths were disproportionately thin with marked globular irregularities in single teased nerve fibres and evidence of chronic demyelination. The majority of axons were preserved but axonal spheroids and cytoskeletal abnormalities akin to neuroaxonal dystrophy were noted. Membrane-bound multilobulated lysosomal inclusions of floccular and electron-dense material were present in Schwann cells (SC), endoneurial fibroblasts, macrophages, pericytes and endothelial cells. SC of myelinated fibres were stuffed with whorls of concentric osmiophilic membranous profiles and electron-lucent material. The findings are diagnostic and differ from those of classical Niemann-Pick disease. 相似文献
108.
以四川地区1例无症状携带丁型肝炎病毒(HDV)和乙型肝炎病毒(HBV)患者的外周血为标本,采用逆转录-PCR技术,获得了HDV全基因组的cDNA克隆(HDVSZ93株),全长1684bp。与世界其他七个地区株相比,其核酸同源性为81.8%~95.4%;丁肝病毒抗原蛋白编码区核酸同源性为88.9%~96.1%,氨基酸同源性为86,4%~93.0%。另从1例慢性重型肝炎患者血清内克隆了丁肝病毒抗原蛋白(HDAg)编码基因(HDV-SZ92株),与SZ93株相比,亦存在若干变异。对这些不同地区、不同病情HDV株变异的可能意义进行了讨论。 相似文献
109.
目的观察前列腺素E1治疗慢性乙型肝炎重度黄疸的疗效。方法在综合治疗基础上,分别使用前列腺素E1(治疗组)和门冬氨酸钾镁(对照组)治疗慢性乙型肝炎重度黄疸患者各35例,并观察其症状、体征及肝、肾功能等,疗程4周。结果治疗组的症状、体征及肝功能指标及总有效率,均显著优于对照组,两组比较差异有显著意义(P〈0.05)。结论前列腺素E1治疗慢性乙型肝炎重度黄疸能显著地促进黄疸消退和改善肝功能。 相似文献
110.
The peptide Leu-Asp-Asp-Ser-Lys-Arg-Val-Ala-Lys-Arg-Lys-Leu-Ile-Glu, which corresponds to sequence 124 to 137 of c-erb-A protein, was synthesized and tested as substrate for protein kinase C (PKC). Although a typical recognition sequence for PKC, consisting of a cluster of basic residues, is found on the C-terminus side of serine, its phosphorylation was totally prevented by the presence of the two acidic residues on the amino-terminus side. Three analogs in which aspartyl residues were successively replaced with alanine were studied and the influence of the acidic side chain in modulating phosphorylation by PKC was thus possible to determine. The results show that the presence of a single aspartyl residue located in positions i-1 or i-2 with respect to the phosphorylable residue can almost totally abolish the positive effect of a highly favorable cluster of basic residues. These observations highlight the role of negative substrate specificity determinants in settling the protein substrate profile of protein kinase C. 相似文献