全文获取类型
收费全文 | 182285篇 |
免费 | 17302篇 |
国内免费 | 11833篇 |
专业分类
耳鼻咽喉 | 1629篇 |
儿科学 | 1905篇 |
妇产科学 | 2429篇 |
基础医学 | 21875篇 |
口腔科学 | 3259篇 |
临床医学 | 23917篇 |
内科学 | 26708篇 |
皮肤病学 | 2211篇 |
神经病学 | 9505篇 |
特种医学 | 6461篇 |
外国民族医学 | 97篇 |
外科学 | 18586篇 |
综合类 | 29595篇 |
现状与发展 | 39篇 |
一般理论 | 22篇 |
预防医学 | 12225篇 |
眼科学 | 4758篇 |
药学 | 19719篇 |
189篇 | |
中国医学 | 10931篇 |
肿瘤学 | 15360篇 |
出版年
2024年 | 733篇 |
2023年 | 2983篇 |
2022年 | 7787篇 |
2021年 | 9781篇 |
2020年 | 7349篇 |
2019年 | 6293篇 |
2018年 | 6622篇 |
2017年 | 6075篇 |
2016年 | 5685篇 |
2015年 | 8723篇 |
2014年 | 10581篇 |
2013年 | 9777篇 |
2012年 | 14252篇 |
2011年 | 15400篇 |
2010年 | 9828篇 |
2009年 | 7560篇 |
2008年 | 10044篇 |
2007年 | 9537篇 |
2006年 | 9131篇 |
2005年 | 8870篇 |
2004年 | 5679篇 |
2003年 | 5146篇 |
2002年 | 4262篇 |
2001年 | 3600篇 |
2000年 | 3797篇 |
1999年 | 3853篇 |
1998年 | 2288篇 |
1997年 | 2344篇 |
1996年 | 1784篇 |
1995年 | 1736篇 |
1994年 | 1512篇 |
1993年 | 907篇 |
1992年 | 1281篇 |
1991年 | 1116篇 |
1990年 | 895篇 |
1989年 | 843篇 |
1988年 | 762篇 |
1987年 | 623篇 |
1986年 | 458篇 |
1985年 | 396篇 |
1984年 | 190篇 |
1983年 | 162篇 |
1982年 | 93篇 |
1981年 | 123篇 |
1980年 | 79篇 |
1979年 | 108篇 |
1978年 | 52篇 |
1977年 | 51篇 |
1976年 | 42篇 |
1974年 | 44篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
131.
应用单链构象多态性分析多聚酶链反应EB染色法(PCR-SSCP-EB)对40例肺癌组织标本的P53基因序列5~8外显子突变进行分析,同时应用PCR方法检测上述标本及18例肺良性疾病组织标本中HPV16、18型DNA相关序列,旨在分析二者在肺鳞癌发病中的作用及相互关系,并就肺鳞癌与P53基因结构和功能异常的关系进行初步探讨。 相似文献
132.
建立了小鼠脾脏、胸腺细胞体外转化微量培养系统,确定了最佳实验条件.点蜡法充CO_2,简便易行,效果好.RPMI-1640培养基内补充胎牛血清,其浓度确定为在脾细胞培养为10%,在胸腺细胞培养为20%.脾细胞培养最适细胞密度为2~5×10~6/ml,Con A最适量为2~4μg/培养;胸腺细胞培养细胞最适密度为1×10~7/ml,Con A最适量为2~4μg/培养.两种已知免疫活性的药物在脾细胞培养体系有明确肯定的反应. 相似文献
133.
真皮下血管网岛状皮瓣抗菌力的实验研究 总被引:2,自引:0,他引:2
为研究真皮下血管网薄皮瓣用于感染创面的可行性,在家猪臀部两侧分别形成以旋髂深血管主干分支为蒂的传统岛状皮瓣和远侧50%修薄的真皮下血管网岛状皮瓣。用细菌计数、吖啶橙荧光染色测定白细胞吞噬指数和白细胞内杀菌率,应用激光多普勒、墨汁灌注、透明标本等方法,对两种皮瓣的抗菌力作自身对照研究。结果表明,真皮下血管网岛状皮瓣的抗菌力明显降低,可能与皮瓣修薄后血供减少,白细胞功能相应降低有关。 相似文献
134.
Further studies of the role of Ser-16 in the regulation of the activity of phenylalanine hydroxylase. 总被引:3,自引:1,他引:2 下载免费PDF全文
D Kowlessur X J Yang S Kaufman 《Proceedings of the National Academy of Sciences of the United States of America》1995,92(11):4743-4747
It was previously proposed that the activation of rat liver phenylalanine hydroxylase (EC 1.14.16.1) by cAMP-dependent protein kinase-mediated phosphorylation of Ser-16 is due to the introduction of the negatively charged phosphate group. To explore the validity of this proposal, we have applied site-directed mutagenesis to specifically replace Ser-16 with negatively charged amino acids, glutamic and aspartic; with polar uncharged amino acids, asparagine and glutamine; with the positively charged amino acid lysine; and with the nonpolar hydrophobic amino acid alanine. The wild-type and mutant enzymes were purified to homogeneity, and the importance of Ser-16 in the activation of phenylalanine hydroxylase was examined by comparing the state of activation of the phosphorylated form of the wild-type hydroxylase with that of the mutants. The kinetic studies carried out on the wild-type phosphorylated hydroxylase showed that all the activation could be accounted for by an increase in Vmax with no change in Km for either phenylalanine or the pterin cofactor. Replacement of Ser-16 with a negatively charged residue, glutamate of aspartate, resulted in the activation of the hydroxylase by 2- to 4-fold, whereas replacement with glutamine, asparagine, lysine, or alanine resulted in a much more modest increase. Further, lysolecithin was found to stimulate the phosphorylated hydroxylase and the mutant enzymes S16E and S16D by a factor of 6-7. In contrast, the mutants S16Q, S16N, and S16A all showed the same magnitude of activation as the wild-type with lysolecithin. Therefore, this study demonstrates that activation of the enzyme by phosphorylation of Ser-16 by cAMP-dependent protein kinase is due to the introduction of negative charge(s) and strongly suggests the involvement of electrostatic interaction between the regulatory and catalytic domains of the hydroxylase. 相似文献
135.
136.
T J Yang 《In vivo (Athens, Greece)》1987,1(5):297-302
Canine cyclic hematopoiesis (CH) was first described in Gray Collies as the lethal gray syndrome, and was subsequently shown to be a counterpart of human cyclic neutropenia (CN). The disease is characterized by a recurrent cyclic change in the levels of neutrophils and other blood elements at approximately 12-day intervals. It is caused by an autosomally recessive gene with pleiotropic effects or a CH gene which is closely linked to a gray color gene. The infectious insult on affected animals is periodic but its clinical and pathologic effects are continual and cumulative Affected dogs die after weaning and rarely survive over 6 months of age. There is evidence of immunoregulatory defects in these dogs. Reciprocal bone marrow transplantation indicates that the defect resides in the bone marrow, but the actual site and mechanism of the defect has not been established. The disease in Gray Collies represents a unique model system for studying the mechanism of cyclic hematopoiesis and hematopoietic regulation. Studies of the disease have made conceptual contributions toward understanding and treatment of human cyclic neutropenia. 相似文献
137.
Hsiu Hui Chiu Hsiao Hui Chou Wen Dar Jean Wung Yang Shieh 《Journal of microbiology, immunology, and infection》2007,40(1):14-23
BACKGROUND AND PURPOSE: Marine luminous bacteria were isolated and identified from samples in shallow coastal waters of Taiwan during the relatively warm seasons. METHODS: Identification of the luminous isolates was performed based on differences of phenotypic and genotypic characteristics together with data from phylogenetic analysis. RESULTS: Twenty seven strains of marine luminous bacteria were isolated. They were divided into five types based on differences of phenotypic characteristics. However, they could be clustered into only two genotypes according to the analysis of restriction patterns of polymerase chain reaction-amplified 16S rRNA genes digested with various restriction enzymes. The characterization data together with the 16S rRNA gene-based phylogenetic analysis revealed that the isolates included in phenotype I (seven isolates) could be Photobacterium leiognathi, and those included in phenotypes II-V (twenty isolates) might be classified as Vibrio harveyi. However, phylogeny based on gyrB sequences indicated that phenotypes II-V could be classified into two species, V. harveyi and Vibrio campbellii. CONCLUSION: Culturable luminous bacteria in the shallow coastal waters of Taiwan during the sampling period are dominated by V. harveyi/campbellii and P. leiognathi, and the former species appeared to be more prevalent and numerous than the latter species in general. 相似文献
138.
下肢郁积性溃疡是由于下肢静脉曲张引起局部血液回流障碍、组织营养不良、抵抗力降低而引起局部皮肤破溃甚至感染形成溃疡[1].常规的外科清洁换药治疗效果不理想.我科自2003年以来采用自制的溃疡油进行换药,取得了明显的效果.现介绍如下.…… 相似文献
139.
目的 了解本社区高血压患者的危险因素现状,探讨干预对策。方法 采用分层整群抽样的方法,随机抽取社区4个里委2级、3级高血压患者402例作为研究对象,收集各项危险因素如性别、年龄、血脂、血糖、吸烟、饮食、体育锻炼、体重等,并进行统计分析。结果402例高血压患者1年内进行所有相关辅助检查者有14例,占3.48%;1年内进行相关辅助检查一项者306例,占76.12%。饮食控制及进行体育锻炼有300例,占74.43%;吸烟62例,占15.42%。结论 高血压患者对饮食控制及体育锻炼、吸烟有害的知晓率明显提高,而对相关辅助检查认识不足。 相似文献
140.
武汉西马街社区成人健康相关危险因素调查 总被引:1,自引:0,他引:1
目的 探讨当地成人健康相关危险因素构成,尝试低费用下开展此类监测的方法。方法 依托教育系统对武汉市江岸区西马街地区成人进行随机抽样入户问卷调查。结果 人群吸烟率32.4%,男性吸烟率60.6%,中年人高于老年人,女性吸烟率5.9%;92.5%的人不愿意自己的孩子在将来成为烟民;人群饮洒率为26.5%,其中男性饮洒率51%,23.5%的饮酒者存在违意饮酒情节;33.3%的成人有体育锻炼习惯,其比例随文化程度的升高而升高;19%的人每周户外活动时间达不到1天1小时;35.6%的人存在体重过重问题,分解19.2%为超重,14.7%为肥胖,1.7%为Ⅱ度肥胖。人群自述(非现场测量)高血压患病率为11.1%,自述糖尿病患病率为2.8%,但自觉有糖尿病典型症状而从未检测血糖的比例达16%。结论 落实社区人群基础医学检查任务迫切,依托教育系统进行的成人健康相关危险因素监测方法足当前经济适用的监测方法。 相似文献