全文获取类型
收费全文 | 616篇 |
免费 | 60篇 |
国内免费 | 3篇 |
专业分类
耳鼻咽喉 | 1篇 |
儿科学 | 102篇 |
妇产科学 | 3篇 |
基础医学 | 53篇 |
口腔科学 | 36篇 |
临床医学 | 73篇 |
内科学 | 142篇 |
皮肤病学 | 15篇 |
神经病学 | 37篇 |
特种医学 | 49篇 |
外科学 | 38篇 |
综合类 | 16篇 |
一般理论 | 2篇 |
预防医学 | 31篇 |
眼科学 | 13篇 |
药学 | 27篇 |
中国医学 | 1篇 |
肿瘤学 | 40篇 |
出版年
2021年 | 8篇 |
2020年 | 5篇 |
2019年 | 16篇 |
2018年 | 4篇 |
2017年 | 4篇 |
2016年 | 9篇 |
2015年 | 8篇 |
2014年 | 9篇 |
2013年 | 20篇 |
2012年 | 20篇 |
2011年 | 17篇 |
2010年 | 16篇 |
2009年 | 20篇 |
2008年 | 23篇 |
2007年 | 20篇 |
2006年 | 30篇 |
2005年 | 28篇 |
2004年 | 19篇 |
2003年 | 15篇 |
2002年 | 17篇 |
2001年 | 21篇 |
2000年 | 21篇 |
1999年 | 16篇 |
1998年 | 16篇 |
1997年 | 14篇 |
1996年 | 24篇 |
1995年 | 17篇 |
1994年 | 14篇 |
1993年 | 16篇 |
1992年 | 15篇 |
1991年 | 8篇 |
1990年 | 11篇 |
1989年 | 12篇 |
1988年 | 14篇 |
1987年 | 14篇 |
1986年 | 11篇 |
1985年 | 15篇 |
1984年 | 16篇 |
1983年 | 10篇 |
1982年 | 11篇 |
1981年 | 18篇 |
1980年 | 10篇 |
1978年 | 4篇 |
1977年 | 6篇 |
1976年 | 5篇 |
1975年 | 6篇 |
1973年 | 3篇 |
1970年 | 3篇 |
1969年 | 5篇 |
1966年 | 2篇 |
排序方式: 共有679条查询结果,搜索用时 15 毫秒
1.
2.
This paper describes the clinical presentation of food allergy and/or intolerance (F.A.I.). The role of a diagnostic dietary trial is reviewed. Finally dietary management is discussed. 相似文献
3.
A homologous radioimmunoassay for the measurement of epidermal growth factor (EGF) levels in pig tissues and body fluids has been developed using an antiserum to recombinant porcine EGF. The assay is highly specific, showing no cross-reactivity with a variety of other polypeptides including the structurally related protein, transforming growth factor-alpha. Furthermore, < 1% cross-reactivity was observed with mouse EGF emphasizing the necessity for homologous assays for EGF measurement. Immunoreactive EGF was present in extracts of pig kidney and pancreas (3.44 +/- 0.43 and 0.76 +/- 0.13 (S.E.M.) pmol/g wet weight respectively), but was not detected in extracts of submaxillary gland or liver. Although immunoreactive EGF was not detectable in uterine, allantoic or ovarian follicular fluids, colostrum contained EGF at biologically active concentrations (0.84 +/- 0.15 nmol/l). Immunoreactive EGF was also present in pig urine, with similar concentrations in samples from male or female animals. In addition, pig urine inhibited the binding of 125I-labelled EGF to 3T3 fibroblasts and stimulated DNA synthesis in quiescent monolayers of these cells, indicating that the immunoreactive material in urine is biologically active. Quantitative comparisons of the data presented here with that published previously indicate considerable species variation in the EGF levels of various tissues and body fluids. 相似文献
4.
The ultrastructures and distributions of the discrete anatomical synapses which constitute two distinct types of output connections made by individual ocellar L-neurons, L1-3, are described. Outputs to neurones L4-5 are excitatory and transmit tonically, whereas reciprocal connections among the three L1-3 neurones are inhibitory and incapable of transmission for longer than a few milliseconds. The tonically transmitting synapses are located in the lateral ocellar tract and are made between the axons of L1-3, which do not receive inputs, and short branches of L4-5, which make no outputs. Each excitatory connection is composed of a few hundred discrete anatomical synapses, each characterised by a bar-shaped presynaptic density which is 0.15-1.5 microns in length and associated with a large number of round synaptic vesicles. Two postsynaptic profiles are apposed to each presynaptic density. Associated with tonic synapses are abundant invaginations of the presynaptic membrane. Synapses of the reciprocal, inhibitory, phasic connections occur in the protocerebral arbors of L1-3, among numerous output synapses of these neurones. Each phasic connection is composed of a few tens of discrete anatomical synapses. Each bar-shaped presynaptic density is associated with two postsynaptic profiles, and is 0.1-1.0 microns long. Compared with the tonic, excitatory connection, there are fewer vesicles and fewer invaginations of the presynaptic membrane associated with each synapse. 相似文献
5.
A S Adamson T J Littlewood G J Poston J M Hows J N Wolfe 《Journal of the Royal Society of Medicine》1988,81(10):609-610
6.
7.
Sonography of testicular microlithiasis 总被引:1,自引:0,他引:1
Diego Jaramillo Antonio Perez-Atayde Rita Littlewood Teele M.D. 《Urologic radiology》1989,11(1):55-57
The sonographic appearance of testicular microlithiasis detected in a patient presenting with torsion is described. A "speckled" pattern of multiple, tiny bright echoes is produced by calcific concretions in the seminiferous tubules and seems to be characteristic of microlithiasis. Although this condition is not treatable, it should be recognized because it is often associated with extratesticular abnormalities and can obscure superimposed testicular disease. 相似文献
8.
Rodney A. Bray Thomas H. Cribb Andrea Waeschenbach D. Timothy J. Littlewood 《Acta parasitologica / Witold Stefański Institute of Parasitology, Warszawa, Poland》2007,52(3):206-212
A new species of Acanthocolpidae, Stephanostomum adlardi is described from the serranid Plectropomus leopardus from Lizard Island in the northern Great Barrier Reef. It differs from all previously described acanthocolpids in the structure
of the oral sucker which is extended into dorsal and ventral lobes each bearing a row of spines. A phylogenetic tree estimated
from combined nuclear small and partial large ribosomal RNA gene sequences shows that, despite the unusual oral sucker structure,
the species is a true member of the genus Stephanostomum. The molecular results also suggest that Monostephanostomum nolani is derived from within Stephanostomum. 相似文献
9.
Littlewood D 《Health and social service journal》1983,93(4873):1381-1382
10.
This study was designed to compare the growth of Pakistani schoolchildren in the UK with the 1990 UK growth standards. Measurements of height, weight, and sitting height were performed on 785 Pakistani schoolchildren aged 5-14 years with the mean values for each age and sex being plotted on the UK growth standards. The results were expressed as SD scores relative to the 1990 reference data. The mean height for the boys was only 0.2 SD scores below the mean for the new growth standards with the mean height for the girls being 0.4 SD scores below the mean. The mean values for weight and body mass index were 0.3 and 0.5 SD scores less than the mean for boys and girls respectively. This study demonstrates that the growth of Pakistani schoolchildren in the UK is comparable to the 1990 UK growth standards with only minor differences. It is not safe to assume that short stature or low body weight in a Pakistani child is due to his or her ethnic background. 相似文献