全文获取类型
收费全文 | 32532篇 |
免费 | 2153篇 |
国内免费 | 1109篇 |
专业分类
耳鼻咽喉 | 189篇 |
儿科学 | 511篇 |
妇产科学 | 436篇 |
基础医学 | 6043篇 |
口腔科学 | 751篇 |
临床医学 | 3541篇 |
内科学 | 4906篇 |
皮肤病学 | 477篇 |
神经病学 | 1555篇 |
特种医学 | 1219篇 |
外国民族医学 | 12篇 |
外科学 | 1898篇 |
综合类 | 4732篇 |
现状与发展 | 3篇 |
预防医学 | 2741篇 |
眼科学 | 291篇 |
药学 | 2972篇 |
8篇 | |
中国医学 | 1144篇 |
肿瘤学 | 2365篇 |
出版年
2024年 | 58篇 |
2023年 | 326篇 |
2022年 | 697篇 |
2021年 | 887篇 |
2020年 | 891篇 |
2019年 | 874篇 |
2018年 | 881篇 |
2017年 | 864篇 |
2016年 | 907篇 |
2015年 | 1041篇 |
2014年 | 1796篇 |
2013年 | 1897篇 |
2012年 | 1850篇 |
2011年 | 2243篇 |
2010年 | 1734篇 |
2009年 | 1764篇 |
2008年 | 1827篇 |
2007年 | 1899篇 |
2006年 | 1729篇 |
2005年 | 1617篇 |
2004年 | 1427篇 |
2003年 | 1308篇 |
2002年 | 1119篇 |
2001年 | 1029篇 |
2000年 | 827篇 |
1999年 | 617篇 |
1998年 | 588篇 |
1997年 | 586篇 |
1996年 | 455篇 |
1995年 | 445篇 |
1994年 | 378篇 |
1993年 | 234篇 |
1992年 | 174篇 |
1991年 | 160篇 |
1990年 | 101篇 |
1989年 | 57篇 |
1988年 | 55篇 |
1987年 | 43篇 |
1986年 | 40篇 |
1985年 | 56篇 |
1984年 | 63篇 |
1983年 | 47篇 |
1982年 | 44篇 |
1981年 | 41篇 |
1980年 | 21篇 |
1979年 | 25篇 |
1978年 | 15篇 |
1977年 | 12篇 |
1973年 | 10篇 |
1972年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
聚合酶链反应在鼠疫菌检测中的应用 研究 总被引:2,自引:0,他引:2
本文采用聚合酶链反应(PCR)技术,通过扩增鼠疫菌9.5kb质粒pla基础上一个478bl片段,用于鼠疫菌检测,被试的45株鼠疫菌扩增产物经琼脂糖凝胶电泳分析均呈现单一DNA带,其分子量大小与预期结果符合。而假结核菌和一株缺6MD质粒鼠疫菌未见扩增带,洽部实验可在4h内完成。本法具有快速、特异、敏感等优点,可用于不同生态型鼠疫菌的快速诊断和流行病学研究. 相似文献
72.
Clinical and diagnostic DNA laboratories must maintain a large inventory of DNA probes for use in hybridization studies. The preparation of plasmid DNA and isolation of DNA fragments for use as probes in both expensive and time consuming. We present here a rapid and relatively inexpensive method of producing large amounts of DNA fragments from stocks, using the polymerase chain reaction (PCR). Our experience over the past year using this technique has been very positive and we believe many laboratories could benefit by employing such a labor-saving approach to maintaining DNA probes. The technique uses the bacteriophage M13 DNA sequencing primers to amplify cloned inserts contained in commonly used plasmid vectors. As examples, we illustrate the use of DNA produced in this manner as probes for linkage analysis of the fragile X syndrome and for detection of deletions in the Duchenne muscular dystrophy gene. We have also found that at least two probes can be amplified in the same PCR reaction, allowing the detection of two different restriction fragment length polymorphisms (RFLP) simultaneously. It should be possible for laboratories to devise strategies particular to their individual needs using more than one DNA probe produced in the same PCR reaction to detect RFLP's. Such strategies would need only to consider that the predicted alleles of the multiple polymorphisms do not migrate to the same position during electrophoresis. Stocks of single or multiple probes produced by the PCR could then be maintained for more rapid Southern analyses. 相似文献
73.
Hans Brunner Thomas C Wetter Birgit Hogl Alexander Yassouridis Claudia Trenkwalder Elisabeth Friess 《Movement disorders》2002,17(5):928-933
We investigated non-rapid eye movement (non-REM) sleep in patients with newly diagnosed Parkinson's disease (PD) who had never previously received dopaminergic medication. There were no significant differences in the conventional sleep parameters between de novo patients with PD and a healthy control group, but the length of stage 1 sleep and the number of awakenings increased significantly upon administration of dopaminergic drugs. Analyzing the quantitative electroencephalogram (EEG), we observed a significant reduction in the low-delta frequency range and a nonsignificant increase in the sigma frequency range in de novo patients with PD. The dopaminergic medication also nonsignificantly reduced the low-delta and sigma frequencies, the latter to the level of the controls. Possible mechanisms that may account for the observed differences are discussed. It is suggested that Parkinson's disease as well as the application of dopaminergic drugs exerts a desynchronizing effect on the sleep EEG that is reflected in a disruption of sleep continuity. 相似文献
74.
75.
本实验用荧光组化技术及记录显微自动曝光时间方法研究了马桑内酯所致的Wistar大鼠癫痫持续状态黑质-腹侧被盖区多巴胺含量的变化。结果显示癫痫发作高峰组(10只)和发作后组(8只)该区多巴胺含量明显低于对照组(10只)和发作前组(10只)。由于多巴胺是一种抑制性神经递质,它的减少可能表明抑制作用的下降对癫痫的发作有一定的调控作用。 相似文献
76.
近年来,超声定量检查技术在临床的应用为心血管疾病患者的心功能评估提供了量化的依据,本文介绍了超声诊断仪的使用部分最新定量检查技术。 相似文献
77.
目的:了解黏膜相关淋巴瘤的凋亡水平及其所涉及到的信号传导通路。方法:收集33例胃肠黏膜相关淋巴样组织(MALT)淋巴瘤病例,通过TUNEL技术原位检测MALT淋巴瘤肿瘤细胞的凋亡水平,通过逆转录聚合酶链反应(RT-PCR)和免疫组织化学染色检测肿瘤的凋亡抑制蛋白2编码基因(API2)和Caspase3 mRNA及蛋白,对API2和Caspase3水平作半定量和定量分析。根据凋亡检测结果将全部病例分为两组,即凋亡细胞数每50个高倍视野小于或等于2的病例组和大于2的病例组,比较2组的API2和Caspase3 mRNA及蛋白。结果:半数以上的MALT淋巴瘤中存在凋亡抑制;凋亡抑制的MALT淋巴瘤病例中API2 mRNA及蛋白水平明显高于没有明显凋亡抑制的病例,但Caspase3 mRNA及蛋白水平在两组病例中表达没有明显的差异。结论:MALT淋巴瘤中存在明显的凋亡抑制,其发生与凋亡抑制因子API2的表达上调有关,但API2对凋亡的调节与Caspase3有关的信号传导通路无明显相关。 相似文献
78.
显微定量法测定中成药中猪牙皂的含量 总被引:2,自引:0,他引:2
目的 :制定猪牙皂在脐风散与惊风散中的显微定量标准。方法 :用显微定量法 ,以猪牙皂特有的石细胞为显微特征物 ,对脐风散与惊风散中的猪牙皂进行测定。结果 :猪牙皂含量与每毫克特征数呈显著的线性正相关 ,回归方程为 y =61 .42 x -1 .1 0× 1 0 - 3(γ=1 .0 0 ,α=0 .0 5 )。结论 :显微定量法测定脐风散与惊风散中猪牙皂的含量是可行的 ,结果可靠 相似文献
79.
80.
J. D. Martins J. P. Monteiro M. C. Antunes-Madeira A. S. Jurado V. M. C. Madeira 《Toxicology in vitro》2003,17(5-6):595
Microorganisms are very powerful tools for the supply of information about the toxic effects of lipophilic compounds, since an impairment of cell growth usually occurs as a result of perturbations related, in most cases, with the partition of toxicants in membranes. The thermophilic eubacterium Bacillus stearothermophilus has been used as a model system to identify α- and β-endosulfan interactions with the membrane possibly related with the insecticide toxicity. Two approaches have been pursued: (a) bacterial growth is followed and the effects of endosulfan isomers determined; (b) biophysical studies with the fluorescent fluidity probe 1,6-diphenyl-1,3,5-hexatriene (DPH) were performed to assess the effects of α- and β-endosulfan on the organization of the membrane lipid bilayer. The effects on growth were quantitatively evaluated by determination of growth parameters, namely the lag phase, the specific growth rate and the cell density reached by cultures in the stationary phase. Growth inhibition by α and β-endosulfan dependent on the concentration is diminished or removed by the addition of 2.5 m
Ca2+ to bacterial cultures. Fluorescence DPH polarization consistently showed opposite effects of Ca2+ and α- and β-endosulfan on the physical state of bacterial polar lipid dispersions. 相似文献