全文获取类型
收费全文 | 35935篇 |
免费 | 3033篇 |
国内免费 | 1711篇 |
专业分类
耳鼻咽喉 | 376篇 |
儿科学 | 720篇 |
妇产科学 | 615篇 |
基础医学 | 3624篇 |
口腔科学 | 721篇 |
临床医学 | 4284篇 |
内科学 | 5875篇 |
皮肤病学 | 527篇 |
神经病学 | 1876篇 |
特种医学 | 1129篇 |
外国民族医学 | 10篇 |
外科学 | 2856篇 |
综合类 | 5599篇 |
现状与发展 | 10篇 |
一般理论 | 3篇 |
预防医学 | 3113篇 |
眼科学 | 1039篇 |
药学 | 3827篇 |
23篇 | |
中国医学 | 2146篇 |
肿瘤学 | 2306篇 |
出版年
2024年 | 158篇 |
2023年 | 469篇 |
2022年 | 1056篇 |
2021年 | 1480篇 |
2020年 | 1143篇 |
2019年 | 988篇 |
2018年 | 1186篇 |
2017年 | 1079篇 |
2016年 | 1000篇 |
2015年 | 1460篇 |
2014年 | 1795篇 |
2013年 | 1956篇 |
2012年 | 2821篇 |
2011年 | 2980篇 |
2010年 | 2091篇 |
2009年 | 1672篇 |
2008年 | 2202篇 |
2007年 | 2119篇 |
2006年 | 1958篇 |
2005年 | 1803篇 |
2004年 | 1412篇 |
2003年 | 1305篇 |
2002年 | 1222篇 |
2001年 | 951篇 |
2000年 | 898篇 |
1999年 | 696篇 |
1998年 | 294篇 |
1997年 | 282篇 |
1996年 | 237篇 |
1995年 | 226篇 |
1994年 | 153篇 |
1993年 | 117篇 |
1992年 | 231篇 |
1991年 | 194篇 |
1990年 | 164篇 |
1989年 | 159篇 |
1988年 | 135篇 |
1987年 | 110篇 |
1986年 | 101篇 |
1985年 | 67篇 |
1984年 | 49篇 |
1983年 | 30篇 |
1982年 | 20篇 |
1981年 | 16篇 |
1980年 | 12篇 |
1979年 | 15篇 |
1977年 | 17篇 |
1976年 | 11篇 |
1974年 | 11篇 |
1973年 | 13篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
The present study in rats evaluates the effects of the ovariectomy (OVX) with and without the simultaneous administration of 17beta-estradiol (17betaE(2)) on oxidative stress and hyperlipidemic nephropathy induced by a single high dose of adriamycin (AD). OVX enhances oxidative stress and worsens nephropathy induced by AD. These changes are prevented by simultaneous administration of 17betaE(2). OVX alone induced oxidative stress and hyperlipidemia without biochemical evidence of renal dysfunction. Our results revealed that ovarian hormones, especially estrogens, have a protective effect against oxidative stress and nephropathy induced by AD. Since the reactive oxygen species plays a role in the pathogenesis of renal lesion, it is important to emphasize that estrogens and their hydroxylated compounds function as biological antioxidants. 相似文献
92.
93.
儿童功能性消化不良与幽门螺杆菌感染的关系 总被引:7,自引:1,他引:7
目的探讨儿童功能性消化不良与幽门螺杆菌(HP)感染的关系。方法用ELISA法和胃液尿素酶试验检测163例功能性消化不良和54例健康儿童的HP感染情况。结果血清HP-IgG阳性申功能性消化不良组高于对照组(43.6%:14.8%,X2=14.7,p<0.01),尿素酶试验阳性率功能性消化不良组也高于对照组(15.3%:3.7%,x2=5.07,p<o.05)。内镜检查15例患儿中,慢性胃炎12例(占80%)。经抗HP治疗功能性消化不良症状消失。结论儿童功能性消化不良与HP感染相关,HP是该疾病的主要病因之一。 相似文献
94.
A comprehensive review of the natural history of Helicobacter pylori infection in children 总被引:3,自引:0,他引:3
Torres J Pérez-Pérez G Goodman KJ Atherton JC Gold BD Harris PR la Garza AM Guarner J Muñoz O 《Archives of medical research》2000,31(5):431-469
Across populations of children, Helicobacter pylori prevalence ranges from under 10% to over 80%. Low prevalence occurs in the U.S., Canada, and northern and western Europe; high prevalence occurs in India, Africa, Latin America, and eastern Europe. Risk factors include socioeconomic status, household crowding, ethnicity, migration from high prevalence regions, and infection status of family members. H. pylori infection is not associated with specific symptoms in children; however, it is consistently associated with antral gastritis, although its clinical significance is unclear. Duodenal ulcers associated with H. pylori are seldom seen in children under 10 years of age. H. pylori-infected children demonstrate a chronic, macrophagic, and monocytic inflammatory cell infiltrate and a lack of neutrophils, as compared with the response observed in adults. The effect of H. pylori infection on acid secretion in children remains poorly defined. The events that occur during H. pylori colonization in children should be studied more thoroughly and should include urease activity, motility, chemotaxis, adherence, and downregulation of the host response. The importance of virulence determinants described as relevant for disease during H. pylori infection has not been extensively studied in children. Highly sensitive and specific methods for the detection of H. pylori in children are needed, especially in younger pediatric populations in which colonization is in its early phases. Criteria for the use of eradication treatment in H. pylori-infected children need to be established. Multicenter pediatric studies should focus on the identification of risk factors, which can be used as prognostic indicators for the development of gastroduodenal disease later in life. 相似文献
95.
Different astroglial reaction between the vagal dorsal motor nucleus and nucleus ambiguus following vagal-hypoglossal nerve anastomosis in cats 总被引:1,自引:0,他引:1
The dorsal motor nucleus of the vagus (DMV) and nucleus ambiguus (NA) were both traced with horseradish peroxidase (HRP) retrograde labelling technique after vagal-hypoglossal nerve anastomosis (VHA). By light microscopy, reinnervation of the new target, viz. tongue skeletal musculature, by DMV and NA was established at 22 days postoperation (dpo) as shown by the neuronal labelling with HRP. Ultrastructurally, signs of retrograde degeneration occurred in some DMV and NA neurons between 3 and 25 days after VHA. The incidence of darkened dendrites, an early sign of dendritic loss, was more common in the DMV compared to the NA. Accompanying the neuronal alteration were drastic astrocytic reactions in the DMV, but not in the NA. Between 3 and 7 dpo, the astrocytes in the DMV showed extensively hypertrophied processes and by 22 dpo, the somata and dendrites of HRP-labelled DMV neurons, but not NA's, appeared to be delineated by the increased lamellar astrocytic processes. Such a feature was sustained throughout the remaining postoperative intervals up to 500 dpo. It is concluded that the DMV motoneurons being autonomic in nature are probably not conducive to the newly acquired target organ. Hence, the insulation of the regenerating DMV motoneurons by the astroglial ensheathment would be vital in the neuronal remodelling and reconstruction of the vagal-hypoglossal pathway. 相似文献
96.
Fatal familial insomnia: clinical, neuropathological, and genetic description of a Spanish family 总被引:1,自引:0,他引:1 下载免费PDF全文
Tabernero C Polo JM Sevillano MD Muñoz R Berciano J Cabello A Báez B Ricoy JR Carpizo R Figols J Cuadrado N Claveria LE 《Journal of neurology, neurosurgery, and psychiatry》2000,68(6):774-777
The clinical presentation and evolution, neuropathological findings, and genotyping of three members of a Spanish family affected with fatal familial insomnia are reported. The mother and two of her offspring developed a rapidly evolving disease with insomnia and behavioural disorders as the initial symptoms and died between 5 and 10 months after the onset of the illness. Frontal brain biopsy in the mother disclosed only non-significant spongiosis, and full neuropathological examination of her offspring showed thalamic and olivary degeneration with isolated focal cortical spongiosis. Genetic examination could only be performed in the contemporary patients and both harboured the prion protein (PrP) 178Asn mutation and homozygous 129 Met/Met genotype. 相似文献
97.
The localization of nitrergic cells and fibers and cholinergic cells has been analyzed in the spinal cord of the anuran amphibian Rana perezi. Histochemistry for nicotinamide adenine dinucleotide phosphate-diaphorase and nitric oxide synthase immunohistochemistry revealed a concurrent pattern of labeled structures. A large population of nitrergic spinal neurons was found from the level of the obex to the filum terminale. They are abundant in the dorsal horn and intermediate gray matter, but also occur in territories of the ventral horn and, only occasionally, in somatic motoneurons. Numerous nitrergic fibers were present in the spinal white matter, particularly in the dorsal and dorsolateral funiculi. A special arrangement of nitrergic axons is present in Lissauer's tract, where a collateral system is formed. Cholinergic cells, revealed by choline acetyltransferase immunohistochemistry, were observed throughout the spinal cord. The somatic motoneurons were the most conspicuously immunoreactive cells. A large population of cholinergic cells forms a discontinuous column in the intermediate gray, from the third spinal segment to lumbar segments. These cells were organized in a medially located or intercalated cell group, and a laterally located intermediolateral group. Numerous scattered cholinergic cells were present in the central zone of the ventral horn and were absent in the dorsal horn. Double-labeling experiments revealed a high degree of codistribution of nitrergic and cholinergic cells, mainly in the intermediate gray, but colocalization of both markers in the same neurons was not found. This result contrasts with the situation found in mammals and raises the question of whether coexpression of both substances was acquired in spinal cord neurons through evolution only in amniotes or, even, only in mammals. 相似文献
98.
99.
100.
Purpose: To investigate the relationships between the axonal sprouting and target neurotization by central neurons after nerve heterocon-nection. Methods: Unilateral (right) vagal-hypoglossal nerve anastomosis (VHA) was performed in adult cats. Following 3-315 days postoperation (dpo), quantitative analyses and ultrastructural changes in the proximal portion of the vagal-hypoglossal heteroconnected nerve as well as the time course of neuronal regeneration were studied. Along with this, horseradish peroxidase (HRP) retrograde tracing technique was used to label the neurons of dorsal motor vagal nucleus (DMV) and nucleus ambiguus (NA) to ascertain if target neurotization was established. Results: The contralateral (left) intact vagus nerve proximal to the level of ansa cervicalis showed an average of 33 +/- 1 myelinated and 74 +/- 4 unmyelinated axons in 727 &mgr;m(2) sectional area of the nerve. In the heteroconnected nerve at the corresponding level just proximal to the anastomosis site, there was a marked increase in the number of small axons sprouting from the unmyelinated nerve fibers between 18 and 25 dpo. The number of these axonal sprouts appeared to decline at 32 dpo but its increase of 131 % was sustained until the late regeneration stage at 315 dpo when compared with the contralateral nerve serving as a control. The mean number of myelinated axons per area unit (727 &mgr;m(2)) was reduced to 18 at 3 dpo but was immediately restored to the normal range at 7 dpo. The retrograde labelling of neurons in both the DMV and NA was first detected at 22 dpo and was progressively increased peaking by about 67 dpo. Conclusions: We conclude that compared with the unmyelinated axons, the myelinated axons may acquire a superior interaction with the new target. Furthermore, the postoperative neurotization of tongue muscles may initiate and facilitate the retraction of the redundant axonal sprouts. 相似文献