全文获取类型
收费全文 | 1731篇 |
免费 | 228篇 |
国内免费 | 20篇 |
专业分类
耳鼻咽喉 | 16篇 |
儿科学 | 59篇 |
妇产科学 | 21篇 |
基础医学 | 160篇 |
口腔科学 | 26篇 |
临床医学 | 275篇 |
内科学 | 400篇 |
皮肤病学 | 36篇 |
神经病学 | 278篇 |
特种医学 | 119篇 |
外国民族医学 | 1篇 |
外科学 | 232篇 |
综合类 | 61篇 |
现状与发展 | 20篇 |
预防医学 | 101篇 |
眼科学 | 36篇 |
药学 | 72篇 |
中国医学 | 2篇 |
肿瘤学 | 64篇 |
出版年
2024年 | 7篇 |
2023年 | 43篇 |
2021年 | 27篇 |
2020年 | 28篇 |
2019年 | 20篇 |
2018年 | 72篇 |
2017年 | 75篇 |
2016年 | 45篇 |
2015年 | 55篇 |
2014年 | 59篇 |
2013年 | 88篇 |
2012年 | 53篇 |
2011年 | 65篇 |
2010年 | 84篇 |
2009年 | 108篇 |
2008年 | 60篇 |
2007年 | 57篇 |
2006年 | 57篇 |
2005年 | 50篇 |
2004年 | 47篇 |
2003年 | 53篇 |
2002年 | 63篇 |
2001年 | 60篇 |
2000年 | 40篇 |
1999年 | 44篇 |
1998年 | 41篇 |
1997年 | 38篇 |
1996年 | 47篇 |
1995年 | 36篇 |
1994年 | 24篇 |
1993年 | 30篇 |
1992年 | 21篇 |
1991年 | 25篇 |
1990年 | 28篇 |
1989年 | 33篇 |
1988年 | 30篇 |
1987年 | 30篇 |
1986年 | 23篇 |
1985年 | 29篇 |
1984年 | 11篇 |
1983年 | 13篇 |
1982年 | 10篇 |
1979年 | 9篇 |
1978年 | 15篇 |
1977年 | 12篇 |
1976年 | 12篇 |
1975年 | 12篇 |
1972年 | 6篇 |
1971年 | 8篇 |
1969年 | 7篇 |
排序方式: 共有1979条查询结果,搜索用时 0 毫秒
1.
2.
Association of human polyomavirus JC with peripheral blood of immunoimpaired and healthy individuals
Drries Kristina Sbiera Silviu Drews Klaus Arendt Gabriele Eggers Christian Drries Rdiger 《Journal of neurovirology》2003,9(1):81-87
JC virus (JCV) infection is regularly asymptomatic in healthy individuals. In contrast, in immunocompromised individuals, highly activated virus replication may lead to PML. Peripheral blood cells (PBCs) are found to habor JCV DNA in healthy and diseased individuals and it is discussed that they might be responsible for dissemination of the virus to the central nervous system (CNS) during persistence. To better understand the role of JCV DNA in PBCs for persistent infection and pathogenesis, the authors characterized the extent of JCV infection in Ficoll-gradient purified blood cells (peripheral blood mononuclear cells [PBMCs]) of healthy and human immunodeficiency virus type 1 (HIV-1)-infected individuals. Virus activation in PBMCs from healthy JCV-infected individuals was found at a rate of 0% to 38% at low polymerase chain reaction (PCR) sensitivity. In progressive multifocal leukoencephalopathy (PML) patients, a stronger signal was found, indicating increased virus activation. JCV DNA was regularly detected in T and B lymphocytes and in monocytes at low levels. However, granulocytes were shown to be the predominant reservoir of JCV DNA harboring high copy numbers. Although the overall distribution of viral genomes holds true for the population studied, in the individual, a markedly changed pattern of distribution can be found. 相似文献
3.
This paper introduces the design and implementation of a generic wireless and Real-time Multi-purpose Health Care Telemedicine system applying Bluetooth protocol, Global System for Mobile Communications (GSM) and General Packet Radio Service (GPRS). The paper explores the factors that should be considered when evaluating different technologies for application in telemedicine system. The design and implementation of an embedded wireless communication platform utilising Bluetooth protocol is described, and the implementation problems and limitations are investigated. The system is tested and its telecommunication general aspects are verified. The results showed that the system has (97.9 +/- 1.3)% Up-time, 2.5 x 10(-5) Bit Error Rate, 1% Dropped Call Rate, 97.4% Call Success Rate, 5 second transmission delay in average, (3.42 +/- 0.11) kbps throughput, and the system may have application in electrocardiography. 相似文献
4.
5.
D M Arendt J C Whitt J R Vinton L D Kiselica 《Journal of the American Dental Association (1939)》1989,119(6):737-739
A case of oral lichen planus has been discussed. The causes, associated conditions, laboratory tests, and treatment were addressed. The use of cyanoacrylate "super glue" may have acted as a contactant and promoted the patient's localized lichenoid process. No additional treatment was provided other than confirmation of clinical suspicions. The most important factor was ruling out the possibility of a dysplastic or a malignant process. Should the patient become symptomatic, the treatment would probably start out with kaolin and pectin (Kaopectate) lidocaine/benadryl rinses. Should supportive therapy fail, alternative regimens including topical to systemic corticosteroids would be considered. 相似文献
6.
Miettinen R Riedel A Kalesnykas G Kettunen HP Puoliväli J Soininen H Arendt T 《Journal of chemical neuroanatomy》2005,30(2-3):105-118
Reelin, an extracellular matrix protein has an important role in the migration, correct positioning and maturation of neurons during development. Though it is generally down-regulated in the postnatal period, expression of this large glycoprotein continues in the adult brain in some cell populations. In the present study, we examined the distribution of reelin-immunoreactivity (-ir) in the hippocampal formation of 9-month-old wildtype mice (WT). Then, reelin-ir in normal mice was compared to that of transgenic mice (APP/PS1) carrying mutated human APP and PS1 genes, which are linked to the familial form of Alzheimer's disease (AD). The APP/PS1 mice were additionally burdened with a second risk factor for AD, namely depletion of circulating gonadal hormones by ovariectomy (APP/PS1 + OVX). The analyses revealed that in adult WT reelin-ir is expressed by Cajal-Retzius cells and a subgroup of interneurons throughout the hippocampal formation. In addition, layer II projection neurons in the lateral entorhinal subfields are reelin-ir. Interestingly, ovariectomy decreases the number of reelin-ir cells in the hilus in WT mice, whereas AD-related genotype alone induces only a non-significant reduction. Unexpectedly, additional stress, e.g., depletion of gonadal hormones, does not aggravate the slight reduction in the reelin cell number in the APP/PS1 mice. We propose that the changes in normal reelin-ir are linked to disturbances in repair mechanisms in which APP/PS1 and gonadal hormones are involved and which are perturbed in neurodegenerative conditions, namely AD. 相似文献
7.
After a transient or permanent unilateral denervation of the soleus muscle of the rat the number, distribution and length of muscle spindles were determined. The results were compared with those of the contralateral innervated muscle and with the data received from investigating soleus muscles of normal uninjured rats. Denervation (with or without reinnervation) reduces the number of muscle spindles by nearly 50%. The typical uniform distribution of muscle spindles in the muscle remains almost unchanged. The remaining muscle spindles grow longer. The same findings are observed in the contralateral still innervated muscles, too. Consequently a comparison of the denervated (reinnervated) muscle exclusively with its contralateral muscle does not show different counts of muscle spindles. Therefore in such investigations the contralateral muscle is of dubious value as a mean of control. As regards number, distribution and length of muscle spindles there exist only small differences between the various strains of rats. 相似文献
8.
9.
Melatonin output covaries with sleepiness, with both peaking early morning. Bright white light suppresses this output, but it is not known if such treatment ameliorates nighttime sleepiness during sleep deprivation. However, sleep-deprived subjects find such light irritating. Humans are particularly sensitive to green light, and melatonin output is more readily suppressed by this hue. A pilot study using different green light regimens showed that sleep-deprived subjects well tolerated 2,000 lux green light given 10 min hourly, and that this dose reduced nighttime melatonin output. The main study gave this light treatment vs. a low intensity red/green light control, from 1900 hr for 11 hr, to two groups of subjects (n = 6 each) sleep deprived for 36 hr. Urine was collected at 6-hr intervals during sleep loss and on a baseline day. Vigilance performance, subjective sleepiness, and oral temperature were monitored during sleep loss. The experimental condition suppressed urine 6-hydroxymelatonin sulfate (aMT6s) output between 0000 hr and 0600 hr, and increased it 0600-1200 hr; but there was no change in total 24-hr values. The control condition had no such effects. The oral temperature rhythm remained unchanged. Vigilance and subjective sleepiness were improved significantly relative to control values during 0000-0600 hr; these improvements were maintained somewhat over the 0600-1200-hr period, contrary to what one might expect if the delayed melatonin surge at this time was increasing sleepiness. Although the bright green light helped counteract sleepiness, any causal link with changes in melatonin output seem tenuous. 相似文献
10.
Mahadevaiah SK; Odorisio T; Elliott DJ; Rattigan A; Szot M; Laval SH; Washburn LL; McCarrey JR; Cattanach BM; Lovell-Badge R; Burgoyne PS 《Human molecular genetics》1998,7(4):715-727
An RNA-binding motif (RBM) gene family has been identified on the human Y
chromosome that maps to the same deletion interval as the 'azoospermia
factor' (AZF). We have identified the homologous gene family (Rbm) on the
mouse Y with a view to investigating the proposal that this gene family
plays a role in spermatogenesis. At least 25 and probably >50 copies of
Rbm are present on the mouse Y chromosome short arm located between Sry and
the centromere. As in the human, a role in spermatogenesis is indicated by
a germ cell-specific pattern of expression in the testis, but there are
distinct differences in the pattern of expression between the two species.
Mice carrying the deletion Yd1, that maps to the proximal Y short arm, are
female due to a position effect resulting in non-expression of Sry ;
sex-reversing such mice with an Sry transgene produces males with a high
incidence of abnormal sperm, making this the third deletion interval on the
mouse Y that affects some aspect of spermatogenesis. Most of the copies of
Rbm map to this deletion interval, and the Yd1males have markedly reduced
Rbm expression, suggesting that RBM deficiency may be responsible for, or
contribute to, the abnormal sperm development. In man, deletion of the
functional copies of RBM is associated with meiotic arrest rather than
sperm anomalies; however, the different effects of deletion are consistent
with the differences in expression between the two species.
相似文献