全文获取类型
收费全文 | 157555篇 |
免费 | 15388篇 |
国内免费 | 9275篇 |
专业分类
耳鼻咽喉 | 1185篇 |
儿科学 | 2162篇 |
妇产科学 | 1660篇 |
基础医学 | 22310篇 |
口腔科学 | 2883篇 |
临床医学 | 18992篇 |
内科学 | 21167篇 |
皮肤病学 | 1708篇 |
神经病学 | 7301篇 |
特种医学 | 5571篇 |
外国民族医学 | 65篇 |
外科学 | 14970篇 |
综合类 | 27233篇 |
现状与发展 | 30篇 |
一般理论 | 12篇 |
预防医学 | 11763篇 |
眼科学 | 3627篇 |
药学 | 18169篇 |
145篇 | |
中国医学 | 9352篇 |
肿瘤学 | 11913篇 |
出版年
2024年 | 558篇 |
2023年 | 2181篇 |
2022年 | 6035篇 |
2021年 | 7838篇 |
2020年 | 5768篇 |
2019年 | 4983篇 |
2018年 | 5192篇 |
2017年 | 4934篇 |
2016年 | 4612篇 |
2015年 | 6861篇 |
2014年 | 8535篇 |
2013年 | 8605篇 |
2012年 | 12044篇 |
2011年 | 12649篇 |
2010年 | 9193篇 |
2009年 | 7519篇 |
2008年 | 8877篇 |
2007年 | 8829篇 |
2006年 | 7987篇 |
2005年 | 7150篇 |
2004年 | 5517篇 |
2003年 | 5271篇 |
2002年 | 4463篇 |
2001年 | 3781篇 |
2000年 | 3234篇 |
1999年 | 2720篇 |
1998年 | 1684篇 |
1997年 | 1794篇 |
1996年 | 1269篇 |
1995年 | 1203篇 |
1994年 | 1094篇 |
1993年 | 770篇 |
1992年 | 973篇 |
1991年 | 888篇 |
1990年 | 797篇 |
1989年 | 726篇 |
1988年 | 656篇 |
1987年 | 555篇 |
1986年 | 530篇 |
1985年 | 425篇 |
1984年 | 371篇 |
1983年 | 303篇 |
1982年 | 268篇 |
1981年 | 229篇 |
1980年 | 196篇 |
1979年 | 198篇 |
1978年 | 192篇 |
1977年 | 211篇 |
1976年 | 191篇 |
1974年 | 156篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
991.
Changes in muscle electrical activity were studied during local static work until “refusal” under ordinary conditions and during inhibition of the program monitoring functions of the cortex (in the somnambulic stage of hypnosis). The experimental results show that the duration of maintenance of static effort in hypnosis was twice that in the control, and electrical activity of the muscles was increased on the average by 1.5–2 times or, in some experiments, by 3–4 times. In the light of these results the mechanism of formation of “refusal” to work may assume the form of active cessation of activity of the central structures responsible for the program monitoring function. 相似文献
992.
993.
Analysis of the butyrylcholinesterase gene and nearby chromosome 3 markers in Alzheimer disease 总被引:3,自引:0,他引:3
Brindle N; Song Y; Rogaeva E; Premkumar S; Levesque G; Yu G; Ikeda M; Nishimura M; Paterson A; Sorbi S; Duara R; Farrer L; St George-Hyslop P 《Human molecular genetics》1998,7(5):933-935
The K-variant of butyrylcholinesterase (BCHE-K) recently has been reported
to be associated with Alzheimer disease (AD) in carriers of the epsilon4
allele of the apolipoprotein E (APOE) gene. We have re- examined the
frequency of the BCHE-K allele in a large data set of both sporadic and
familial cases of AD disease, and we have also examined the segregation of
three genetic markers on chromosome 3 near BCHE . Our data neither support
an association of BCHE-K with sporadic or familial AD, nor do they suggest
the existence of another gene nearby on chromosome 3 as a common cause of
familial AD.
相似文献
994.
通过人工合成了人类免疫缺陷性病毒(Humanimmunodeficiencyvirus,HIV)糖蛋白肽GP120对人和无脊椎动物(Mytilusedulis)免疫细胞的抑制作用的研究。人单核细胞和Mytilusedulis免疫细胞分别与GP120保温后,均抑制细胞的吞噬细菌(Psudomonasstretzi)作用。应用计算机显微图像术(Computer-assistedmicroscopy)直 相似文献
995.
Yu WH Zhao KW Ryazantsev S Rozengurt N Neufeld EF 《Molecular genetics and metabolism》2000,71(4):573-580
The Sanfilippo syndrome type B (MPS III B) is an autosomal recessive disease caused by deficiency of alpha-N-acetylglucosaminidase (EC 3. 2.1.50), one of the lysosomal enzymes required for the degradation of heparan sulfate. The disease is characterized by profound neurodegeneration but relatively mild somatic manifestations, and is usually fatal in the second decade. A mouse model had been generated by disruption of the Naglu gene in order to facilitate the study of pathogenesis and the development of therapy for this currently untreatable disease. Recombinant human alpha-N-acetylglucosaminidase (rhNAGLU) was prepared from secretions of Lec1 mutant Chinese hamster ovary cells. The enzyme, which has only unphosphorylated high-mannose carbohydrate chains, was endocytosed by mouse peritoneal macrophages via mannose receptors, with half-maximal uptake at ca. 10(-7) M. When administered intravenously to 3 month-old mice, rhNAGLU was taken up avidly by liver and spleen but marginally if at all by thymus, lung, kidney, heart, and brain (in order of diminishing uptake). The half-life of the enzyme was 2.5 days in liver and spleen. Immunohistochemistry and electron microscopy showed that only macrophages were involved in enzyme uptake and correction in these two organs, yet the storage of glycosaminoglycan was reduced to almost normal levels. The results show that the macrophage-targeted rhNAGLU can substantially reduce the body burden of glycosaminoglycan storage in the mouse model of Sanfilippo syndrome III B. 相似文献
996.
997.
目的:构建携带小鼠FoxP3基因的重组腺相关病毒,并检测其在NIH3T3细胞的表达情况。方法:将FoxP3通过内部核糖体进入位点(IRES)与报告基因增强型绿色荧光蛋白连接,构建同时含有目的基因和报告基因的重组腺相关病毒(rAAV)表达质粒,通过磷酸钙沉淀法共转染HEK293细胞,收获并通过肝素亲和层析法纯化病毒,并对病毒纯度和滴度进行鉴定。利用携带FoxP3基因的重组病毒体外感染小鼠NIH3T3细胞,体外观察感染效率和目的基因转录情况。结果:包装成功的rAAV/FoxP3经纯化后获得了高纯度的rAAV/FoxP3,实时定量PCR检测rAAV/FoxP3的病毒滴度达到5.0×1012vg/mL,体外感染NIH3T3细胞,流式细胞术测定感染效率可达92.88%,实时PCR测定细胞内存在高水平FoxP3mRNA。结论:获得携带FoxP3-IRES-EGFP的rAAV,并可有效感染NIH3T3细胞,为进一步研究FoxP3的生物学功能提供了有效工具。 相似文献
998.
人白细胞介素12在哺乳动物细胞中的稳定表达及其生物活性的研究 总被引:1,自引:0,他引:1
目的采用遗传基因工程方法获得具有生物活性的人白细胞介素12,探索其治疗肿瘤和慢性肝炎的可行性。方法采用已克隆的国人IL-12基因序列,利用内部核糖体切入位点(IRES)完成IL-12P35、P40双亚基共表达载体的构建,通过转染CHODHFR缺陷细胞,双抗夹心ELISA法筛选阳性克隆,MTX加压扩增,PCR检测其基因整合,T淋巴细胞增殖和诱生γ干扰素实验检测其生物活性。结果获得了稳定高效表达人IL-12的工程细胞系,表达产物为70×103左右的糖蛋白。结论本研究得到的基因重组人IL-12具有良好的生物活性,有强的诱导产生γ干扰素的能力和诱导活化T淋巴细胞增殖能力。 相似文献
999.
目的 了解初中新生慢性鼻-鼻窦炎发病与鼻中隔偏曲的相关性。 方法 分层随机抽取郑州市1910名12~15岁初中新生,采取问卷调查及专科体检的形式,根据量表、体检结果,了解鼻中隔偏曲和慢性鼻-鼻窦炎患病情况,分析两者相关性。 结果 抽样初中新生慢性鼻-鼻窦炎的患病率为6.2%(119/1910);慢性鼻-鼻窦炎患病群体与非患病群体中,轻、中度鼻中隔偏曲的发生率分别为27.7%(33/119)和31.2%(559/1791),两者差异无统计学意义(χ2=0.632,P>0.05);重度鼻中隔偏曲的发生率分别为13.4%(16/119)和8.0%(144/1791),两者差异有统计学意义(χ2=4.248,P<0.05)。 结论 初中新生慢性鼻-鼻窦炎发病与重度鼻中隔偏曲具有相关性。 相似文献
1000.
Alexander Yu Donald Turbiville Fangling Xu Joseph W. Ray Allison D. Britt Pamela J. Lupo Sunil K. Jain Karen E. Shattuck Sally S. Robinson Jianli Dong 《American journal of medical genetics. Part A》2019,179(11):2178-2189
Duplications in the 22q11.2 region can cause 22q11.2 duplication syndrome and encompass a variety of phenotypes including developmental delays, facial abnormalities, cardiovascular defects, central nervous system delays, and other congenital abnormalities. However, the contribution of these contiguous duplicated regions to the clinical phenotypes has not been fully elucidated. In this study, we identified nine patients carrying different 22q11.2 microduplications detected by chromosomal microarray. Of these patients, seven pediatric patients presented with various clinical features including two neonate cases died shortly after birth, and two healthy adults. We examined region specific genotype–phenotype associations and found unpredictability associated with 22q11.2 duplications in these nine patients. 相似文献