全文获取类型
收费全文 | 1322篇 |
免费 | 112篇 |
国内免费 | 2篇 |
专业分类
耳鼻咽喉 | 10篇 |
儿科学 | 40篇 |
妇产科学 | 32篇 |
基础医学 | 224篇 |
口腔科学 | 36篇 |
临床医学 | 185篇 |
内科学 | 235篇 |
皮肤病学 | 50篇 |
神经病学 | 66篇 |
特种医学 | 99篇 |
外国民族医学 | 2篇 |
外科学 | 94篇 |
综合类 | 54篇 |
预防医学 | 150篇 |
眼科学 | 16篇 |
药学 | 77篇 |
中国医学 | 3篇 |
肿瘤学 | 63篇 |
出版年
2021年 | 25篇 |
2019年 | 14篇 |
2018年 | 20篇 |
2016年 | 15篇 |
2015年 | 16篇 |
2014年 | 27篇 |
2013年 | 35篇 |
2012年 | 39篇 |
2011年 | 55篇 |
2010年 | 35篇 |
2009年 | 29篇 |
2008年 | 40篇 |
2007年 | 58篇 |
2006年 | 37篇 |
2005年 | 50篇 |
2004年 | 31篇 |
2003年 | 21篇 |
2002年 | 63篇 |
2001年 | 57篇 |
2000年 | 30篇 |
1999年 | 28篇 |
1998年 | 27篇 |
1997年 | 29篇 |
1996年 | 23篇 |
1995年 | 24篇 |
1994年 | 13篇 |
1993年 | 14篇 |
1992年 | 31篇 |
1991年 | 28篇 |
1990年 | 17篇 |
1989年 | 30篇 |
1988年 | 23篇 |
1987年 | 34篇 |
1986年 | 34篇 |
1985年 | 42篇 |
1984年 | 27篇 |
1983年 | 17篇 |
1982年 | 19篇 |
1981年 | 19篇 |
1980年 | 19篇 |
1979年 | 13篇 |
1978年 | 17篇 |
1977年 | 15篇 |
1975年 | 17篇 |
1974年 | 23篇 |
1973年 | 17篇 |
1972年 | 16篇 |
1971年 | 14篇 |
1969年 | 11篇 |
1967年 | 12篇 |
排序方式: 共有1436条查询结果,搜索用时 15 毫秒
1.
2.
In vivo microdialysis coupled with HPLC and radioimmuno-assay techniques were used to analyze dopamine (DA) and neurotensin (NT) in prefrontal cortical extracellular fluid following electrical stimulation of mesocortical axons. The release (overflow into the extracellular fluid) of both DA and NT increased with increasing number of impulses and with frequency. At the lowest frequency tested (2.5 Hz), DA release was significantly increased, while there was no significant increase in the release of NT. As the frequency of stimulation was increased from 2.5 to 20 Hz, the ratio of extracellular DA:NT decreased exponentially. Stimulation in a burst pattern produced greater release of both DA and NT than tonic stimulation when the number of impulses per second and the total number of impulses were held constant. Furthermore, blockade of DA autoreceptors with sulpiride stereoselectively increased the release of DA while decreasing the release of NT. These data suggest that the release of coexistent molecules (DA and NT) from mesocortical neurons can be influenced by physiological and pharmacological factors such that under certain conditions simultaneous or differential release may occur. 相似文献
3.
Both acidic (aFGF) and basic (bFGF) fibroblast growth factors have been shown to be present in the adult rat ventral mesencephalon and to exert effects on cultured mesencephalic cells. In the present study we have examined the expression of aFGF and bFGF in the rat ventral mesencephalon at various stages of development. bFGF was present at all ages examined [embryonic day 16 (E16) to postnatal day 90 (P90)]. In contrast, aFGF was not detectable at embryonic and early postnatal ages, but was observed at later (P20, P60, P90) postnatal stages. These data suggest that aFGF and bFGF may have functions in mesencephalic dopamine neurones in different stages of development. 相似文献
4.
Electron microscopic evidence for the association of M 2 protein with the influenza virion 总被引:4,自引:0,他引:4
D. C. Jackson Xi-Lin Tang K. Gopal Murti R. G. Webster G. W. Tregear W. J. Bean 《Archives of virology》1991,118(3-4):199-207
Summary Immunogold electron microscopy revealed that site-specific antibodies elicited by a synthetic peptide representing the N-terminal sequence (residues 2–10) of influenza virus M 2 protein were capable of binding to the surface of virions. Antibody binding was observed with two human influenza virus strains but not with an avian virus strain which has amino acid substitutions in the appropriate sequence of M 2. These results provide direct evidence for the presence of M 2 in the influenza virion. 相似文献
5.
Calciphylaxis – a topical overview 总被引:3,自引:0,他引:3
G Arseculeratne† AT Evans‡ SM Morley† 《Journal of the European Academy of Dermatology and Venereology》2006,20(5):493-502
'Calciphylaxis', a calcification syndrome associated with ischaemic cutaneous necrosis, is acquired naturally in humans in disease states. It is a life and limb-threatening complication, usually observed in patients with renal disease and secondary hyperparathyroidism, but known to occur in the absence of renal or parathyroid disease. The reported mortality rate, which ranges from 60-80%, relates to wound infection, sepsis and organ failure. It is a small-vessel vasculopathy, which is estimated to occur in about 4% of haemodialysis patients. Clinically, violaceous, reticulate areas of cutaneous necrosis and eschar may be evident, particularly in the extremities. In addition to the clinical picture, a raised calcium phosphorous product, an elevated parathyroid hormone level, radiographic evidence of vessel and soft-tissue calcification and the finding of mural calcification affecting small arteries and arterioles on histopathology help to confirm the diagnosis of this entity which generally has a poor prognosis. A high index of suspicion and an active multidisciplinary management approach, with rigorous attention to wound care and prevention of sepsis, are vital in the management of these patients. In this overview, we discuss the pathophysiology, clinical features and associations, risk factors, diagnosis and management issues relating to calciphylaxis. 相似文献
6.
7.
Mutations in the retinal guanylate cyclase (RETGC-1) gene in dominant cone-rod dystrophy 总被引:3,自引:0,他引:3
Kelsell RE; Gregory-Evans K; Payne AM; Perrault I; Kaplan J; Yang RB; Garbers DL; Bird AC; Moore AT; Hunt DM 《Human molecular genetics》1998,7(7):1179-1184
The dominant cone-rod dystrophy gene CORD6 has previously been mapped to
within an 8 cM interval on chromosome 17p12-p13. The retinal- specific
guanylate cyclase gene (RETGC-1), which maps to within this genetic
interval and previously was implicated in Leber's congenital amaurosis, was
screened for mutations within this family and in a panel of small families
and individuals with various cone and cone- rod dystrophy phenotypes. A
missense mutation (E837D) was identified in affected members of the CORD6
family, as well as a second missense mutation (R838C) in three other
families with dominant cone-rod dystrophy. RETGC-1 is only the fourth gene
to be implicated in cone-rod dystrophy and this is the first report of
dominant mutations in this gene.
相似文献
8.
Casado CG Javier Ortiz G Padron E Bean SJ McKenna R Agbandje-McKenna M Boulton MI 《Virology》2004,323(1):164-171
"Single" T = 1 isometric particles of Maize streak virus (MSV) have been isolated from infected maize leaves. Biochemical and genetic characterizations show that these particles contain subgenomic (sg) MSV DNA encapsidated by the MSV coat protein. The largest sg DNA is 1.56 kb, slightly larger than half genome size, although sg DNAs as small as 0.2 kb were also cloned. The sg DNAs are not infectious, and they do not appear to play a role in the pathogenicity of MSV. This is the first report of sg DNAs for MSV and, to our knowledge, the first time that encapsidated sg DNAs have been characterized at the sequence level for any geminivirus. These data will assist in our investigations into the role of genomic DNA in the formation of the unique geminate capsid architecture of the Geminiviridae. 相似文献
9.
Two groups of 10 female roof rats were mated either in cycling or postpartum estrus to provide a quantitative comparison of copulatory behavior and to compare the stimulus requirements for the initiation of pregnancy. Animals in both estrous conditions were mated to one ejaculation, three ejaculations and to sexual satiety in repeated tests. The results indicate there were no differences between estrous conditions in the qualitative patterns of copulation but that males achieved more intromissions in the first series of postpartum tests than in cycling estrous tests. The stimulus requirements for pregnancy initiation were not found to vary as a function of estrous condition, however it was found that postpartum matings resulted in more pups per litter than did cycling estrous matings. The results were discussed with regard to the functional significance of species differences in copulatory behavior and in stimulus requirements for pregnancy. 相似文献
10.
The in vivo release of dopamine and neurotensin from the rat medial prefrontal cortex was studied using perfusion microdialysis coupled with sensitive radioimmunoassay and HPLC techniques. Following stimulation of dopamine autoreceptors with either apomorphine (30 micrograms/kg, s.c.) or EMD-23448 (10 microM in the perfusion buffer) a decrease in dopamine and an increase in neurotensin release was observed. The release of both substances was measured in the same dialysis sample. These data suggest that activation of dopamine autoreceptors in the prefrontal cortex produces opposing effects on the release of dopamine and neurotensin. 相似文献