全文获取类型
收费全文 | 274678篇 |
免费 | 23260篇 |
国内免费 | 7031篇 |
专业分类
耳鼻咽喉 | 3550篇 |
儿科学 | 5044篇 |
妇产科学 | 4545篇 |
基础医学 | 28149篇 |
口腔科学 | 8091篇 |
临床医学 | 22859篇 |
内科学 | 30492篇 |
皮肤病学 | 3380篇 |
神经病学 | 20192篇 |
特种医学 | 6503篇 |
外国民族医学 | 31篇 |
外科学 | 24221篇 |
综合类 | 41071篇 |
现状与发展 | 17篇 |
一般理论 | 24篇 |
预防医学 | 29345篇 |
眼科学 | 2598篇 |
药学 | 32315篇 |
339篇 | |
中国医学 | 27100篇 |
肿瘤学 | 15103篇 |
出版年
2024年 | 884篇 |
2023年 | 4705篇 |
2022年 | 9098篇 |
2021年 | 12142篇 |
2020年 | 11581篇 |
2019年 | 12917篇 |
2018年 | 11740篇 |
2017年 | 10386篇 |
2016年 | 9560篇 |
2015年 | 9380篇 |
2014年 | 17645篇 |
2013年 | 19200篇 |
2012年 | 16249篇 |
2011年 | 17729篇 |
2010年 | 14413篇 |
2009年 | 13034篇 |
2008年 | 12639篇 |
2007年 | 12382篇 |
2006年 | 10613篇 |
2005年 | 9016篇 |
2004年 | 7777篇 |
2003年 | 6992篇 |
2002年 | 5490篇 |
2001年 | 4624篇 |
2000年 | 4164篇 |
1999年 | 3469篇 |
1998年 | 3190篇 |
1997年 | 2906篇 |
1996年 | 2489篇 |
1995年 | 2171篇 |
1994年 | 1973篇 |
1993年 | 1773篇 |
1992年 | 1476篇 |
1991年 | 1364篇 |
1990年 | 1116篇 |
1989年 | 1028篇 |
1988年 | 930篇 |
1987年 | 833篇 |
1986年 | 810篇 |
1985年 | 2117篇 |
1984年 | 2329篇 |
1983年 | 1460篇 |
1982年 | 1933篇 |
1981年 | 1363篇 |
1980年 | 1139篇 |
1979年 | 980篇 |
1978年 | 794篇 |
1977年 | 599篇 |
1976年 | 722篇 |
1975年 | 506篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Clonal deletion and anergy are two major mechanisms of self-tolerance. However, the molecular mechanisms underlying clonal deletion and anergy, as well as the threshold of TCR affinity/avidity required for these processes, are not known. Expression of the V beta 8.1 TCR correlates with the reactivity of the T cells to the minor lymphocyte stimulating locus-1a (Mls-1a) and T cells expressing this TCR are deleted in the thymus of Mls-1a mice. Similarly, in TCR V beta 8.1 transgenic mice, the number of CD4+CD8-T cells is reduced in Mls-1a mice. However, small numbers of CD4+CD8-T cells remain in the periphery of adult Mls-1a transgenic mice. We have generated T cell clones from TCR V beta 8.1 transgenic mice by stimulation of lymph node T cells with C57BL/6 alloantigens. Interestingly, CD4+CD8-V beta 8.1+ clones isolated from the transgenic mice of Mls-1a background responded to the self-antigen Mls-1a, to which they did not respond in primary assay. Reactive patterns of the clones were compared with clones derived from Mls-1b mice. Proliferation and cytokine production of the clones from Mls-1a mice to the self-antigen Mls-1a were generally reduced when compared with clones from Mls-1b mice. More importantly, T cell clones from Mls-1a mice required more Mls-1a antigen for their activation, and were more susceptible to the inhibitory effects of anti-CD4 antibody on the proliferative responses to Mls-1a than those from Mls-1b mice. These results suggest that the T cell receptor on clones derived from Mls-1a mice have functional but reduced affinity/avidity for self-antigen Mls-1a. 相似文献
992.
Objective Report of two cases of exudative discoid and lichenoid dermatosis (Sulzberger-Garbe), with typical penile lesions. Differential diagnosis of persistent penile plaques. Background Following remission of the generalized eruption of exudative discoid and lichenoid dermatosis (Sulzberger-Garbe), it is not unusual to see a single remaining lesion localized on the penis. Since Sulzberger et al. (Sulzberger MB, Witten VH, Hunt JA. Puzzling persistent penile plaques. Arch Dermatol 1956:73:101-109) reviewed dermatoses presenting with puzzling persistent penile plaques in 1955, further dermatoses have evolved as important differential diagnoses. Much controversy has arisen as to the justification of exudative discoid and lichenoid dermatosis (Sulzberger-Garbe) as a disease entity. Conclusions Diagnosis of most cases of persistent plaques of dermatitis on the penis is possible with a careful examination of the entire skin, and a thorough history to discover past lesions. The possibility of malignancy makes a biopsy mandatory. Exudative discoid and lichenoid chronic dermatosis (Sulzberger-Garbe) typically responds well to systemic steroids. Intrale-sional triamcinolone acetonide has been demonstrated to be effective in the treatment of a persistent penile plaque in exudative discoid and lichenoid dermatosis (Sulzberger-Garbe), and may be helpful in discontinuing or reducing systemic therapy to a level compatible with long-term treatment. 相似文献
993.
In order to analyze the epileptogenic mechanisms of caffaine and related xanthines, putative effects of these drugs were studied on adenosine receptors of CA3 neurons in hippocampal slices. Epileptogenic concentrations of different xanthine derivatives strongly correlated with their affinities for the inhibitory A1 adenosine receptor subtype. The A1 receptor agonists adenosine and R-PIA reversibly depressed xanthine-induced epileptic activity without effects on the resting membrane potential or on spontaneously occuring action potentials. These findings suggest that the epileptogenic potency of xanthines is primarily due to the blockade of the A1 receptors through an abnormal rise of intracellular cAMP and to the excessive transmembrane calcium fluxes underlying paroxysmal depolarization shifts. 相似文献
994.
Exposure of primary cultured astrocytes for 3 days to 1 μM of either dopamine, serotonin or norepinephrine resulted in upregulation (25–34% increase in Bmax) of the peripheral-type benzodiazepine receptors (PBRs) labeled with [3H]Ro5-4864. A similar treatment with γ-aminobutyric acid [GABA] caused a 2-fold increase in the affinity (Kd) of [3H]Ro5-4864. The monoamines tested and GABA had no effect on the binding parameters of [3H]PK 11195, another selective PBR ligand. The present study indicates that Ro5-4864 binding sites are susceptible to regulation by specific neurotransmitters and provides further evidence for the distinction between Ro5-4864 and PK 11195 binding sites of the PBRs in cultured astrocytes. 相似文献
995.
高位食管癌切除颈部胃食管重建术的临床应用和初步评价 总被引:1,自引:0,他引:1
本文报道了我院自1988年至1994年间采用高位食管癌切除颈部胃食管重建术治疗高位食管癌23例的结果,其中男14例,女9例,年龄35-70岁,平均年龄52岁,病变位于颈段者11例,上胸段者12例。2,3,5年生存率分别为62.5%,55.1%,33.3%。同时介绍了手术要点和该术式的优点,并提出了吻合口瘘的预防措施。 相似文献
996.
50种传统清热解毒药的抑菌实验 总被引:13,自引:1,他引:12
本文报告了传统药物文献收载的50种清热解毒药的抑菌实验结果。显示抑菌作用的有41种,占82%。对阳性球菌显示有抑菌作用的有36种;对阴性杆菌显示有抑菌作用的有24种。其中的地胡椒、金果榄、毛果算盘子等显示有较广的抗菌效应,值得进一步研究。 相似文献
997.
In this study, large areas of goldfish telencephalon were ablated including rostral nucleus preopticus periventriculare (rNPP), and degenerating axons were traced by a modified Fink and Heimer procedure. The lesioning procedure ablated large regions of area dorsalis telencephali pars medialis, centralis, and dorsolateral complex; and completely removed area ventralis telencephali pars dorsalis, ventralis, and lateralis. In addition, the supracommissural nucleus and rNPP were lesioned specifically because both nuclei have been thought to be involved in courtship behavior and endocrine control of reproduction. This investigation demonstrated extensive fiber projections from telencephalic nuclei and/or rNPP to the hypothalamus. Lesioned telencephalon and/or rNPP projected bilaterally to nucleus preopticus and the suprachiasmatic nucleus and unilaterally to the following tuberal nuclei: nucleus anterior tuberis, and the lateral hypothalamic nucleus. A much larger fiber projection to the inferior lobe nuclei was also observed with a large contralateral as well as ipsilateral input. 相似文献
998.
Children With Chronic Physical Disorders: Maternal Reports of Their Psychological Adjustment 总被引:7,自引:4,他引:3
Wallander Jan L.; Varni James W.; Babani Lina; Banis Heather Tweddle; Wilcox Karen Thompson 《Journal of pediatric psychology》1988,13(2):197-212
Advances in biomedical science have resulted in dramatic improvementsin the medical care of chronically ill and handicapped children.Past measurement problems have resulted in a lack of clarityregarding the psychological adjustment of these children. Themothers of 270 chronically ill and handicapped children wereadministered the Child Behavior Checklist in an attempt to identifypatterns of behavioral functioning across six pediatric chronicdisorders: juvenile diabetes, spina bifida, hemophilia, chronicobesity, juvenile rheumatoid arthritis, and cerebral palsy.In general, it was found that children in all chronic disordergroups were perceived by their mothers as evidencing on theaverage more behavioral and social competence problems thanexpected based on norms for children in general. However, theirbehavioral and social adjustment was reported as better thanthat of a normative sample of children referred to mental healthclinics. There were essentially no differences between childrenwith different chronic disorders in terms of behavior problemsand social competence. The results were taken to support theview that these children were as a group at risk for adjustmentproblems. They were also discussed in terms of the noncategorialapproach, which suggests that similar psychosocial challengesare faced across pediatric chronic physical disorders. 相似文献
999.
In human cortex and hippocampus area, [3H]5-HT (5 nM) labels 5-HT1A, 5-HT1D and 5-HT1E sites. After masking 5-HT1A receptors by 0.1 μM 8-OH-DPAT, the binding displaced by 0.1 μM 5-CT presumably represented 5-HT1D sites and the remaining binding 5-HT1E sites. In frontal cortex, 5-HT1A receptors represented the main binding in layers II and VI and a lower fraction on other layers. 5-HT1D and 5-HT1E sites, were more homogeneously distributed in layers II to VI (21–34% of specific [3H]5-HT binding). 5-HT1E sites were of similar affinities (KD close to 6–8 nM) in the cortical layers II to VI. In CA1 field of hippocampus, (pyramidal layer, stratum radiatum, molecular layer), CA2 and dentate gyrus, 5-HT1A receptors represented the major fraction, 5-HT1D sites a significant fraction and 5-HT1E a minor fraction of the specific [3H]5-HT binding. In CA3–CA4 fields, 5-HT1A receptors were less densely present, 5-HT1D sites were predominant and 5-HT1E sites represented a significant fraction (27%). The highest densities of 5-HT1E sites have been measured in subiculum, where 5-HT1A, 5-HT1D, and 5-HT1E binding sites were equally represented and in entorhinal cortex where 5-HT1E sites represented the major binding in layer III. They were also present in layers II and IV (29 and 24%) and, to a lesser extent, in layers V and VI. 5-HT1A sites were predominant in layer VI, II and V and were less abundant in other layers. 5-HT1D were homogeneously present in layers II, III, IV and were present in low amounts in other layers. No 5-HT1E were detected in choroid plexus, where [3H]5-HT was dramatically reduced by mesulergine (5-HT2C receptors). No significant displacement of [3H]5-HT by mesulergine was measured in other structures. 相似文献
1000.
本文对300例肛肠疾病采用CO_2激光治疗,治愈率为94.33%,一次切割完成,不需止血缝合,一般7-15天痊愈,疗效明显优于其它治疗方法。 相似文献