全文获取类型
收费全文 | 59971篇 |
免费 | 5919篇 |
国内免费 | 3981篇 |
专业分类
耳鼻咽喉 | 616篇 |
儿科学 | 644篇 |
妇产科学 | 358篇 |
基础医学 | 5937篇 |
口腔科学 | 1346篇 |
临床医学 | 7749篇 |
内科学 | 7971篇 |
皮肤病学 | 521篇 |
神经病学 | 2648篇 |
特种医学 | 2171篇 |
外国民族医学 | 21篇 |
外科学 | 5576篇 |
综合类 | 12742篇 |
现状与发展 | 20篇 |
一般理论 | 1篇 |
预防医学 | 4859篇 |
眼科学 | 1590篇 |
药学 | 6536篇 |
88篇 | |
中国医学 | 4301篇 |
肿瘤学 | 4176篇 |
出版年
2024年 | 205篇 |
2023年 | 836篇 |
2022年 | 2304篇 |
2021年 | 3209篇 |
2020年 | 2406篇 |
2019年 | 1912篇 |
2018年 | 2034篇 |
2017年 | 1958篇 |
2016年 | 1734篇 |
2015年 | 2869篇 |
2014年 | 3579篇 |
2013年 | 3533篇 |
2012年 | 5122篇 |
2011年 | 5298篇 |
2010年 | 3824篇 |
2009年 | 3332篇 |
2008年 | 3619篇 |
2007年 | 3589篇 |
2006年 | 3270篇 |
2005年 | 2764篇 |
2004年 | 2066篇 |
2003年 | 2163篇 |
2002年 | 1712篇 |
2001年 | 1412篇 |
2000年 | 1090篇 |
1999年 | 885篇 |
1998年 | 471篇 |
1997年 | 488篇 |
1996年 | 354篇 |
1995年 | 312篇 |
1994年 | 254篇 |
1993年 | 133篇 |
1992年 | 158篇 |
1991年 | 153篇 |
1990年 | 117篇 |
1989年 | 96篇 |
1988年 | 107篇 |
1987年 | 90篇 |
1986年 | 74篇 |
1985年 | 51篇 |
1984年 | 32篇 |
1983年 | 24篇 |
1982年 | 16篇 |
1981年 | 12篇 |
1980年 | 14篇 |
1979年 | 29篇 |
1976年 | 13篇 |
1974年 | 12篇 |
1972年 | 14篇 |
1968年 | 13篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Omnipaque myelography in diagnosis of lumbar spinal disorders 总被引:5,自引:0,他引:5
22.
23.
24.
25.
Response properties of reticulospinal neurons in the lateral reticular nucleus (LRN) area to natural cutaneous stimulation were investigated systematically in 45 urethane-anesthetized rats by using extracellular recording techniques. A total of 64 neurons were tested with peripheral stimuli, of which 19 were responsive only to noxious stimuli; 7 responsive to both noxious and non-noxious stimuli; 4 responsive only to non-noxious stimuli; and 34 not responsive to any cutaneous stimuli. Both the noxious and non-noxious receptive fields were large and bilateral. Among the neurons responding to noxious stimuli, the majority (72%) was excited. This study provides evidence that some reticulospinal neurons in the rat LRN area are involved in the mechanisms of nociception. 相似文献
26.
27.
Colgin LL Kubota D Brucher FA Jia Y Branyan E Gall CM Lynch G 《Journal of neurophysiology》2004,92(6):3385-3398
Spontaneous negative-going potentials occurring at an average frequency of 0.7 Hz were recorded from the dentate gyrus of slices prepared from the temporal hippocampus of young adult rats. These events (here termed "dentate waves") in several respects resembled the dentate spikes described for freely moving rats during immobile behaviors and slow-wave sleep. Action potentials were observed on the descending portion of the in vitro waves and, as expected from this, whole cell recordings established that the waves were composed of depolarizing currents. Dentate waves appeared to be locally generated within the granule cell layer and were greatly reduced by antagonists of AMPA-type glutamate receptors or by lesions to the entorhinal cortex. Simultaneous recordings indicated that the waves were often synchronized in the inner and outer blades of the dentate gyrus. Knife cuts through the perforant path and the commissural/associational system did not eliminate synchronization, leaving electrotonic propagation via gap junctions as its probable cause. In accord with this, cuts that separated the two blades of the dentate eliminated synchronization between them, and a compound that inhibits gap junctions reduced wave activity. Dentate waves were regularly accompanied by sharp waves in field CA3 and were reduced in size by the acetylcholinesterase inhibitor, physostigmine. It is hypothesized that dentate waves occur when spontaneous glutamate release from dentate afferents produces action potentials in neighboring granule cells that then summate electrotonically into a population event; once initiated, the waves propagate, again electrotonically, and thereby engage a significant portion of the granule cell population. 相似文献
28.
一种可生物降解温度敏感型聚乙二醇-聚己内酯-聚乙二醇水凝胶的合成和表征 总被引:1,自引:0,他引:1
合成了一系列分子量较低的聚乙二醇.聚己内酯-聚乙二醇(Poly(ethylene glycol)-Polycaprolactone-Poly(ethylene glycol),PEG-PCL—PEG)三嵌段共聚物。分别采用FTIR和1H—NMR对其结构进行了表征。所合成的PEG-PCL-PEG共聚物具有良好的水溶性,当水溶液浓度高于临界凝胶浓度(Critical gel concentration,CGC)时,随着温度的变化聚合物水溶液会呈现特有的凝胶-溶胶转变。研究了共聚物亲水疏水链段的比例和长度,以及热历史等对凝胶-溶胶转变行为的影响。通过调节上述条件,可以在一定程度上拓宽凝胶-溶胶转变温度范围,有助于PEG—PCL-PEG水凝胶在可注射药物控制释放系统等方面的应用。 相似文献
29.
Immunohistochemical analysis of centromere protein F expression in buccal and gingival squamous cell carcinoma 总被引:4,自引:0,他引:4
Centromere protein F (CENP-F) expression (localization and characteristics) in relation to tumor clinicopathological parameters was immunohistochemically examined and evaluated in 47 archival biopsy specimens of buccal and gingival squamous cell carcinomas (SCC). Centromere protein F expression was detected in 79% of the samples. An increase in the labeling index (LI) with WHO grading was obtained ( P < 0.05). Correlations were obtained between the CENP-F LI and tumor size ( P < 0.05). Immunoelectron microscopy showed CENP-F nuclear staining as punctate or fine dots. The present study shows that CENP-F expression and detection of a more specific cell subpopulation presents a theoretical advantage for the analysis of the precise cell cycle of G2 to M cells, compared to Ki-67. 相似文献
30.
本文借助电子显微镜技术对 4月胎龄组及 6月胎龄组水囊引产胎儿海马中段部位的凋亡神经元超微结构进行观察、拍照 ,并对结果进行了分析讨论。结果显示 :两组对象中均可见凋亡神经元 ,所见的凋亡神经元的超微结构变化基本相同 ,即细胞核内有明显的染色质边集和凝结成块的现象 ,并可见核膜皱缩和扭曲。另外 ,6月组凋亡细胞的结构变化较 4月组更为明显。在 6月组细胞质内和核内均有小体出现 ,其他细胞器无显著变化。从而更进一步说明在胚胎海马发育中存在着神经元不同性质的死亡现象 -即正常死亡和凋亡。而且提出 6月组显现出更为明显的凋亡神经元形态变化 相似文献