全文获取类型
收费全文 | 733篇 |
免费 | 63篇 |
国内免费 | 18篇 |
专业分类
耳鼻咽喉 | 4篇 |
儿科学 | 23篇 |
妇产科学 | 7篇 |
基础医学 | 140篇 |
口腔科学 | 46篇 |
临床医学 | 50篇 |
内科学 | 160篇 |
皮肤病学 | 19篇 |
神经病学 | 35篇 |
特种医学 | 101篇 |
外科学 | 77篇 |
综合类 | 28篇 |
预防医学 | 26篇 |
眼科学 | 7篇 |
药学 | 44篇 |
中国医学 | 1篇 |
肿瘤学 | 46篇 |
出版年
2023年 | 4篇 |
2022年 | 4篇 |
2021年 | 3篇 |
2020年 | 7篇 |
2019年 | 3篇 |
2018年 | 16篇 |
2017年 | 13篇 |
2016年 | 18篇 |
2015年 | 13篇 |
2014年 | 8篇 |
2013年 | 18篇 |
2012年 | 23篇 |
2011年 | 32篇 |
2010年 | 25篇 |
2009年 | 38篇 |
2008年 | 24篇 |
2007年 | 48篇 |
2006年 | 14篇 |
2005年 | 16篇 |
2004年 | 17篇 |
2003年 | 9篇 |
2002年 | 20篇 |
2001年 | 12篇 |
2000年 | 16篇 |
1999年 | 15篇 |
1998年 | 27篇 |
1997年 | 45篇 |
1996年 | 45篇 |
1995年 | 28篇 |
1994年 | 19篇 |
1993年 | 18篇 |
1992年 | 7篇 |
1991年 | 22篇 |
1990年 | 12篇 |
1989年 | 25篇 |
1988年 | 25篇 |
1987年 | 15篇 |
1986年 | 15篇 |
1985年 | 14篇 |
1984年 | 13篇 |
1983年 | 13篇 |
1982年 | 8篇 |
1981年 | 11篇 |
1980年 | 9篇 |
1979年 | 3篇 |
1978年 | 7篇 |
1977年 | 5篇 |
1976年 | 5篇 |
1975年 | 4篇 |
1969年 | 1篇 |
排序方式: 共有814条查询结果,搜索用时 46 毫秒
111.
Decrements in auditory responses to a repeated conspecific song are long-lasting and require two periods of protein synthesis in the songbird forebrain. 总被引:3,自引:1,他引:2
下载免费PDF全文
![点击此处可从《Proceedings of the National Academy of Sciences of the United States of America》网站下载免费的PDF全文](/ch/ext_images/free.gif)
S J Chew C Mello F Nottebohm E Jarvis D S Vicario 《Proceedings of the National Academy of Sciences of the United States of America》1995,92(8):3406-3410
Earlier work showed that playbacks of conspecific song induce expression of the immediate early gene ZENK in the caudo-medial neostriatum (NCM) of awake male zebra finches and that this response disappears with repeated presentations of the same stimulus. In the present study, we investigated whether repetitions of a song stimulus also elicited a decrement in the electrophysiological responses in the NCM neurons of these birds. Multiunit auditory responses in NCM were initially vigorous, but their amplitude decreased (habituated) rapidly to repeated stimulation, declining to about 40% of the initial response during the first 50 iterations. A similar time course of change was seen at the single unit level. This habituation occurred specifically for each song presented but did not occur when pure tones were used as a stimulus. Habituation to conspecific, but not heterospecific, song was retained for 20 h or longer. Injections of inhibitors of protein or RNA synthesis at the recording site did not affect the initial habituation to a novel stimulus, but these drugs blocked the long-term habituation when injected at 0.5-3 h and at 5.5-7 h after the first exposure to the stimulus. Thus, at least two waves of gene induction appear to be necessary for long-lasting habituation to a particular song. 相似文献
112.
113.
本文研制了以四苯硼—唐松草新碱缔合物为电活性物质的变价态唐松草新碱—PVC膜电极。电极膜按电活性物质:PVC:DBP为1:8:8组成。该电极在pH 5.0~6.0,Ⅰ=0.05的NaCl—HCl溶液中Nernst响应范围为1×10-3~1×10-5mol/L。电极斜率为58.2 mV/logc。检测限为2.5×10-6mol/L。用直接电位法考察了TDH+,TDH2CF++共存时溶液pH和电极斜率S的关系。用S—pH关系,测定了25℃,Ⅰ=0.05时的Ka1值为(2.5±0.2)×10-4,用E—pH关系,测定了25℃,Ⅰ=0.05时的Ka2值为(8.1±0.9)×10-8。 相似文献
114.
Lung involvement in angioimmunoblastic lymphadenopathy (ail) 总被引:2,自引:0,他引:2
115.
柱前荧光标记高效液相色谱法对血浆中l-麻黄碱和d-伪麻黄碱的定量分析 总被引:4,自引:0,他引:4
l-麻黄碱和d-伪麻黄碱是生药麻黄中早为人知而至今仍被广泛用于临床的一对手性异构生物碱。由于二者为生药麻黄中的主要成分但药理活性不同,为便于临床监控及有效用药,高分辨高灵敏度的检测方法的开发迫在眉睫。本文以易于得到的dansylchloride为柱前荧光标识试剂,在确定了最佳衍生化及分离条件的基础上,建立了理想的色谱分析系统(线性检测范围1~800ng·ml-1)。同时运用此方法,完成了对静注l-麻黄碱和d-伪麻黄碱后豚鼠血浆内该对手性异构体水平的考查,并且定量检测了服用中成药小青龙合剂后人血浆中的该对手性异构体。 相似文献
116.
Pachygyriclike changes: topographic appearance at MR imaging and CT and correlation with neurologic status 总被引:3,自引:0,他引:3
Studies of 23 pediatric patients with pachygyriclike changes (PLCs) examined with computed tomography (CT) and magnetic resonance (MR) imaging were reviewed to determine topographic patterns and correlate them with various clinical syndromes and degrees of neurologic impairment. Three types of topographic distributions were identified: unilateral, diffuse, and bilateral nondiffuse (of which eight of 10 showed frontotemporal predominance). PLCs were an isolated finding in seven patients, were associated with various congenital syndromes in nine patients, and were associated with congenital infection in seven patients, six of whom showed marked white matter abnormalities. Although most patients had severe developmental delay, three with nondiffuse PLCs had less severe impairment, permitting less required care. 相似文献
117.
Spirochaetes were isolated from rectal swabs of two homosexuals and the faeces of a third, using simple isolation techniques not previously applied to specimens of this type. The ease of culture of these organisms will enable their distribution and pathogenicity to be studied, particularly in relation to their significance in homosexuals. 相似文献
118.
119.
Herath KB Jayasuriya H Ondeyka JG Polishook JD Bills GF Dombrowski AW Cabello A Vicario PP Zweerink H Guan Z Singh SB 《The Journal of antibiotics》2005,58(11):686-694
The chemokine receptor, CCR2, is predominantly expressed on monocytes/macrophages, and on a subset of memory T cells. It binds to several CC type chemokines of the monocyte chemoattractant protein (MCP) family of which MCP-1 exhibits the highest affinity. CCR2/MCP-1 expression/association in monocyte/macrophage/T cells has been associated with inflammatory processes such as rheumatoid arthritis, multiple sclerosis and atherosclerosis. Neutralization of CCR2 with either a peptide or receptor antagonist results in the prevention of joint swelling in rodent models of arthritis. In this paper, bioassay-guided discovery of CCR2 receptor antagonists derived from natural product extracts are reported. These antagonists belong to two main classes exemplified by bisthiodiketopiperazines and cytochalasins. Six compounds, including emestrin, two new emestrin analogs, and chaetomin represent the first group of compounds. These compounds inhibited the binding of MCP-1 to CCR2 (CHO membrane) with IC50 values of 0.8 to 9 microM and exhibited good activity in a whole cell assay using MCP-1 and human monocytes with IC50's ranging from 4-9 microM. Cytochalasins A and B represented the second group and inhibited the binding activity with IC50 values of 5 and 188 microM, respectively. This is the first report of natural product antagonists of the CCR2 receptor. 相似文献
120.
DS Howale A Mishra AK Asthana D Sharma PG Gaikwad 《Journal of the Anatomical Society of India》2012,61(2):258-261
Biologists and physical anthropologists attempted to classify human being into races according to phenotypic variations. The latter are based either on one or two phenotypic characters therefore the outcome is unable to givq clear distinction among different races. Cranial index seems to be an important,tool, which may be used to identify the races in different geographical regions. 75 dried skulls collected from different part of Maharashtra were measured to determine the cranial index. Skulls were classified by the method of Montagu (1960)2 Average maximum cranial length and breadth were found to be 17.11 cm and 12.98 cm respectively and maximum & minimum cranial lengths were observed to be 18.50 and 16.60 cm and cranial breadths were noted to be 14.50 and 12.10 cm respectively. Average cranial index (mean ± SD) was 75.49 ± 3.95. In our study most of the skulls were grouped under the Mesocranial (46.66%) and Dolichocranial (42.66%) categorises when based on Montagu and Dolichocranial categorises when 56% based Comas'. As per the conclusion Maharashtrian population belongs to Indo-Dravidian race. 相似文献