全文获取类型
收费全文 | 1364篇 |
免费 | 72篇 |
国内免费 | 11篇 |
专业分类
耳鼻咽喉 | 29篇 |
儿科学 | 89篇 |
妇产科学 | 26篇 |
基础医学 | 169篇 |
口腔科学 | 39篇 |
临床医学 | 146篇 |
内科学 | 290篇 |
皮肤病学 | 22篇 |
神经病学 | 55篇 |
特种医学 | 316篇 |
外科学 | 87篇 |
综合类 | 11篇 |
预防医学 | 40篇 |
眼科学 | 8篇 |
药学 | 48篇 |
肿瘤学 | 72篇 |
出版年
2021年 | 18篇 |
2020年 | 6篇 |
2019年 | 8篇 |
2018年 | 16篇 |
2017年 | 6篇 |
2016年 | 10篇 |
2015年 | 25篇 |
2014年 | 25篇 |
2013年 | 37篇 |
2012年 | 22篇 |
2011年 | 22篇 |
2010年 | 33篇 |
2009年 | 35篇 |
2008年 | 23篇 |
2007年 | 50篇 |
2006年 | 33篇 |
2005年 | 32篇 |
2004年 | 38篇 |
2003年 | 18篇 |
2002年 | 23篇 |
2001年 | 20篇 |
2000年 | 20篇 |
1999年 | 27篇 |
1998年 | 96篇 |
1997年 | 73篇 |
1996年 | 79篇 |
1995年 | 54篇 |
1994年 | 55篇 |
1993年 | 62篇 |
1992年 | 13篇 |
1991年 | 17篇 |
1990年 | 18篇 |
1989年 | 49篇 |
1988年 | 35篇 |
1987年 | 38篇 |
1986年 | 28篇 |
1985年 | 34篇 |
1984年 | 29篇 |
1983年 | 18篇 |
1982年 | 22篇 |
1981年 | 25篇 |
1980年 | 32篇 |
1979年 | 10篇 |
1978年 | 16篇 |
1977年 | 18篇 |
1976年 | 20篇 |
1975年 | 15篇 |
1973年 | 6篇 |
1972年 | 7篇 |
1970年 | 5篇 |
排序方式: 共有1447条查询结果,搜索用时 15 毫秒
1.
The distribution and source of a galanin-like innervation of rat salivary glands has been examined. Additionally, submandibular and sublingual acinar cell membrane responses to galanin or a cholinergic agonist were studied. Galanin-immunoreactive fibers were observed throughout the submandibular and sublingual glands in association with ducts and acini. A subset of submandibular ganglion cells expresses galanin immunoreactivity. Parasympathectomy resulted in a marked decrease in galanin immunoreactivity in the glands. Sympathectomy resulted in marked reduction of dopamine beta-hydroxylase immunoreactivity with no appreciable change in galanin immunoreactivity. Retrograde labeling experiments demonstrated that galanin-immunoreactive sensory neurons in the trigeminal ganglion do not innervate the submandibular or sublingual gland. These results indicate that the galanin-like innervation of rat salivary glands is derived from parasympathetic nerves to the glands. Since rat sublingual glands contain largely mucous acini while rat submandibular gland acini are seromucous, electrophysiological responses to galanin and the muscarinic agonist, bethanechol, were compared. Agonist-induced voltage shifts varied between the two glands. The galanin-induced response at the level of the resting membrane potential in submandibular acinar cells was a hyperpolarization, while that in sublingual acinar cells was a depolarization. There was also a greater voltage dependence to the galanin-induced submandibular response than to the sublingual response. Differences were also noted in the acinar cell response to cholinergic stimulation between these glands. These results demonstrate the existence of a galanin-like innervation to salivary glands that may be functionally relevant. Moreover, the results challenge the idea that agonist-induced membrane responses are similar among acinar cells of different glands. 相似文献
2.
3.
4.
5.
6.
Competitive control of the self-renewing T cell repertoire 总被引:1,自引:0,他引:1
We develop a mathematical model for the self-renewing part of the T cell
repertoire. Assuming that self-renewing T cells have to be stimulated by
immunogenic MHC-peptide complexes presented on the surfaces of
antigen-presenting cells, we derive a model of T cell growth in which
competition for MHC-peptide complexes limits T cell clone sizes and
regulates the total number of self-renewing T cells in the animal. We show
that for a sufficient diversity and/or degree of cross-reactivity, the
total T cell number hardly depends upon the diversity of the T cell
repertoire or the diversity of the set of presented peptides. Conversely,
for repertoires of lower diversity and/or cross-reactivity, steady-state
total T cell numbers may be limited by the diversity of the T cells. This
provides a possible explanation for the limited repertoire expansion in
some, but not all, mouse T cell re-constitution experiments. We suggest
that the competitive interactions described by our model underlie the
normal T cells numbers observed in transgenic mice, germ-free mice and
various knockout mice.
相似文献
7.
Disturbances of cell-mediated immunity in ornithosis 总被引:1,自引:0,他引:1
L Konopka S Koba M Partyka K Ma?lanka W Kryczka B Szerszén B Bartosz 《Archivum immunologiae et therapiae experimentalis》1984,32(2):177-184
27 cases of ornithosis were observed during an epidemia in 1980 in Kielce and subsequently followed with respect to immunological characteristics of peripheral blood lymphocytes. Blastic transformation of these cells was tested after stimulation in vitro with three different mitogens. Identification of peripheral blood T and B lymphocytes was done using rosette tests (E,EA,EAC) and the occurrence of surface immunoglobulins was determined by the immunofluorescent method with polyvalent anti-immunoglobulin serum. The counts of T and B lymphocytes in the peripheral blood were normal throughout the whole period of the observation, but from the 3rd week on a significant impairment of 3H-thymidine incorporation into the cells stimulated with Con A was observed, and from the 10th week on, this impairment appeared also in cells stimulated with PHA and PWM. These observations revealed considerable disturbances in cell-mediated reactivity in patients with ornithosis and seem to be connected with chronic infection with Chlamydia psittaci. 相似文献
8.
Localization of a gene for otosclerosis to chromosome 15q25-q26 总被引:5,自引:0,他引:5
Tomek MS; Brown MR; Mani SR; Ramesh A; Srisailapathy CR; Coucke P; Zbar RI; Bell AM; McGuirt WT; Fukushima K; Willems PJ; Van Camp G; Smith RJ 《Human molecular genetics》1998,7(2):285-290
Among white adults otosclerosis is the single most common cause of hearing
impairment. Although the genetics of this disease are controversial, the
majority of studies indicate autosomal dominant inheritance with reduced
penetrance. We studied a large multi- generational family in which
otosclerosis has been inherited in an autosomal dominant pattern. Five of16
affected persons have surgically confirmed otosclerosis; the remaining nine
have a conductive hearing loss but have not undergone corrective surgery.
To locate the disease- causing gene we completed genetic linkage analysis
using short tandem repeat polymorphisms (STRPs) distributed over the entire
genome. Multipoint linkage analysis showed that only one genomic region, on
chromosome 15q, generated a lod score >2.0. Additional STRPs were typed
in this area, resulting in a lod score of 3.4. STRPs FES (centromeric) and
D15S657 (telomeric) flank the 14. 5 cM region that contains an otosclerosis
gene.
相似文献
9.
IMPT1, an imprinted gene similar to polyspecific transporter and multi- drug resistance genes 总被引:5,自引:1,他引:5
Dao D; Frank D; Qian N; O'Keefe D; Vosatka RJ; Walsh CP; Tycko B 《Human molecular genetics》1998,7(4):597-608
Human chromosome 11p15.5 and distal mouse chromosome 7 include a
megabase-scale chromosomal domain with multiple genes subject to parental
imprinting. Here we describe mouse and human versions of a novel imprinted
gene, IMPT1 , which lies between IPL and p57 KIP2 and which encodes a
predicted multi-membrane-spanning protein similar to bacterial and
eukaryotic polyspecific metabolite transporter and multi- drug resistance
pumps. Mouse Impt1 and human IMPT1 mRNAs are highly expressed in tissues
with metabolite transport functions, including liver, kidney, intestine,
extra-embryonic membranes and placenta, and there is strongly preferential
expression of the maternal allele in various mouse tissues at fetal stages.
In post-natal tissues there is persistent expression, but the allelic bias
attenuates. An allelic expression bias is also observed in human fetal and
post-natal tissues, but there is significant interindividual variation and
rare somatic allele switching. The fact that Impt1 is relatively repressed
on the paternal allele, together with data from other imprinted genes,
allows a statistical conclusion that the primary effect of human chromosome
11p15.5/mouse distal chromosome 7 imprinting is domain-wide relative
repression of genes on the paternal homolog. Dosage regulation of the
metabolite transporter gene(s) by imprinting might regulate placental and
fetal growth.
相似文献
10.
Role of nitric oxide in the biology, physiology and pathophysiology of reproduction 总被引:13,自引:0,他引:13
Following its benchmark discovery, nitric oxide (NO) is nowknown to play important functional roles in a variety of physiologicalsystems. Within the vasculature, NO induces vasodilation, inhibitsplatelet aggregation, prevents neutrophil/platelet adhesionto endothelial cells, inhibits smooth muscle cell proliferationand migration, regulates programmed cell death (apoptosis) andmaintains endothelial cell barrier function. NO generated byneurons acts as a neurotransmitter, whereas NO generated bymacrophages in response to invading microbes acts as an antimicrobialagent. Because neurons, blood vessels and cells of the immunesystem are integral parts of the reproductive organs, and inview of the important functional role that NO plays in thosesystems, it is likely that NO is an important regulator of thebiology and physiology of the reproductive system. Indeed, inthe past 10 years, NO has established itself as a polyvalentmolecule which plays a decisive role in regulating multiplefunctions within the female as well as the male reproductivesystem. This review provides an overview of the role of NO invarious reproductive organs under physiological and pathologicalconditions. 相似文献