全文获取类型
收费全文 | 45940篇 |
免费 | 3144篇 |
国内免费 | 2167篇 |
专业分类
耳鼻咽喉 | 71篇 |
儿科学 | 555篇 |
妇产科学 | 206篇 |
基础医学 | 3607篇 |
口腔科学 | 157篇 |
临床医学 | 5307篇 |
内科学 | 7755篇 |
皮肤病学 | 156篇 |
神经病学 | 4870篇 |
特种医学 | 1825篇 |
外国民族医学 | 2篇 |
外科学 | 5811篇 |
综合类 | 9268篇 |
预防医学 | 1545篇 |
眼科学 | 1284篇 |
药学 | 4488篇 |
44篇 | |
中国医学 | 3939篇 |
肿瘤学 | 361篇 |
出版年
2024年 | 137篇 |
2023年 | 583篇 |
2022年 | 1248篇 |
2021年 | 1704篇 |
2020年 | 1490篇 |
2019年 | 1203篇 |
2018年 | 1199篇 |
2017年 | 1305篇 |
2016年 | 1441篇 |
2015年 | 1502篇 |
2014年 | 3024篇 |
2013年 | 3012篇 |
2012年 | 2931篇 |
2011年 | 3186篇 |
2010年 | 2577篇 |
2009年 | 2400篇 |
2008年 | 2573篇 |
2007年 | 2480篇 |
2006年 | 2260篇 |
2005年 | 1988篇 |
2004年 | 1752篇 |
2003年 | 1618篇 |
2002年 | 1327篇 |
2001年 | 1235篇 |
2000年 | 1004篇 |
1999年 | 824篇 |
1998年 | 663篇 |
1997年 | 659篇 |
1996年 | 479篇 |
1995年 | 469篇 |
1994年 | 382篇 |
1993年 | 331篇 |
1992年 | 330篇 |
1991年 | 267篇 |
1990年 | 233篇 |
1989年 | 166篇 |
1988年 | 193篇 |
1987年 | 125篇 |
1986年 | 139篇 |
1985年 | 156篇 |
1984年 | 127篇 |
1983年 | 66篇 |
1982年 | 89篇 |
1981年 | 78篇 |
1980年 | 69篇 |
1979年 | 56篇 |
1978年 | 47篇 |
1977年 | 39篇 |
1976年 | 23篇 |
1973年 | 13篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
Extrapontine and central pontine myelinolysis (EPM/CPM) are rare events in pediatric neurology but can have devastating consequences. They are most commonly associated with rapid correction of hyponatremia but have been reported in other situations as well. This condition is relatively more common in adult neurology, not surprisingly, as alcoholism and associated malnutrition are often predisposing conditions. There have been few case reports in children with regards to this. We describe a 4-year old who presented with focal neurological deficits in the setting of diabetic ketoacidosis and the ensuing underlying osmotic imbalances. The patient made a remarkable recovery with no deficits of note-cognitive or motor. To our knowledge this is the youngest case reported so far of EPM in a child with diabetic ketoacidosis. The history of the condition, early animal experiments, clinicopathologic correlates, previous case reports and other scenarios in which this unusual event can occur are discussed--though the exact pathogenesis of this condition still remains unclear. We hope to bring to the attention of clinicians caring for children in the acute care setting, the importance of gradual correction of serum osmolality to reduce morbidity and mortality. 相似文献
42.
D. Le Elizabeth Eric R. Powers Jian-Ping Bin Howard Leong-Poi N. Craig Goodman Sanjiv Kaul 《Journal of nuclear cardiology》2007,14(2):207-214
Background The mechanism by which transmyocardial revascularization (TMR) offers clinical benefit is controversial. We hypothesized that
TMR ameliorates ischemia by reversing paradoxical catecholamine-induced vasoconstriction.
Methods and Results Chronic ischemic cardiomyopathy was created in 11 dogs by placing ameroid constrictors on the proximal coronary arteries and
their major branches. Six weeks later, 35 channels were created percutaneously in the left circumflex artery region, with
the left anterior descending artery region serving as control. At rest, wall thickening and myocardial blood flow did not
change in the treated region, whereas they deteriorated in the control bed. Contractile and myocardial blood flow reserve
increased in the treated region but deteriorated in the control region. There was diminished iodine 123 metaiodobenzylguanidine
uptake and a significant reduction in noradrenergic nerves in the treated region compared with the control region, with a
corresponding reduction in tissue tyrosine hydroxylase activity.
Conclusions We conclude that the absence of a catecholamine-induced reduction in MBF reserve and contractile reserve in the TMR-treated
region with associated evidence of neuronal injury indicates that the relief of exercise-induced ischemia after TMR most likely
results from reversal of paradoxical catecholamine-induced vasoconstriction. These findings may have implications in selecting
patients who would benefit from TMR.
Supported in part by grants from the National Institutes of Health (R01-HL66034 and K-08-HL074290-01). Bethesda. Md. The radio-labeled
microspheres were provided by DuPont Pharmaceuticals, North Billerica. Mass, and the ultrasound equipment was supplied by
Philips. Andover, Mass. Dr Leong-Poi was the recipient of a Fellowship Training Grant from the Canadian Institute of Health
Research and the Heart and Stroke Foundation of Canada. 相似文献
43.
目的 探讨经尿道切除技术(TUR)治疗下尿路疾病的适应证、操作方法、术中术后处理及并发症预防的要点。方法 应用经尿道汽化电切术(TURVP)和双极等离子汽化电切术(TUPKVP),分别以5%葡萄糖液和生理盐水作冲洗介质,选择性耻骨上膀胱造瘘,持续低压灌洗,术后气囊导尿管留置5~7天拔管,自行排尿。结果 经尿道前列腺双极等离子汽化电切术7例,经尿道前列腺汽化电切术58例,合计前列腺手术65例;腺性膀胱炎汽化电切术43例;膀胱肿瘤汽化电切术15例;后尿道狭窄等离子汽化电切术3例;精阜腺瘤汽化电切术2例。全部病例均一次手术完成,有效率(126/128)98.4%。无膀胱穿孔、电切综合征、大出血、真性尿失禁发生。前列腺术后尿道狭窄、排尿困难再次手术者2例,占3.08%,排尿疼痛、不适感6例,占9.23%,逆行射精4例,占6.15%。结论 TUR技术是一种微创、安全、迅速、有效、恢复快、并发症较少的腔内泌尿外科治疗方法,特别适用于下尿路疾病的手术;术中持续低压灌注对确保切割视野清晰、预防并发症至关重要。 相似文献
44.
加替沙星序贯治疗下呼吸道细菌感染的药物经济学评价 总被引:3,自引:1,他引:2
目的对加替沙星序贯治疗下呼吸道细菌感染进行药物经济学评价。方法将69例下呼吸道细菌性感染患者,随机分为A组(34例)、B组(35例),其中A组采用加替沙星注射液400mg静脉滴注,每天1次,连用10天;B组先用加替沙星注射液400mg静脉滴注,每天1次,3—4天后改为口服400mg,每天1次,连用6—7天,然后对两种方案进行成本-效果分析。结果两组在临床疗效、不良反应发生率及细菌清除率方面差异无统计学意义(P〉0.05);但A组的医疗费用却高于B组(P〈0.01)。结论加替沙星序贯疗法与单纯静脉滴注相比更安全,更经济合理。 相似文献
45.
46.
Nobuyuki Oka Teruaki Kawasaki Kotaro Mizutani Hiroshi Sugiyama Ichiro Akiguchi 《Neuropathology》2007,27(6):509-515
Neuromuscular biopsy is still an essential method for diagnosing vasculitic neuropathy, although its diagnostic sensitivity is at most 60%. Our objective was to examine the expression of hypoxia‐inducible factor 1α (HIF‐1α) in peripheral nerves and to evaluate its usefulness in diagnosing vasculitic neuropathy, especially for discrimination from other axonal neuropathies. Forty‐one patients with vasculitic neuropathy consisting of 20 definite, 14 probable and seven possible diagnoses, 15 patients with metabolic neuropathy, five with motor neuron disease and six with chronic inflammatory demyelinating polyneuropathy were included. Nerve biopsy specimens were immunohistochemically examined for HIF‐1α and various cell markers. Distinct immunoreactivity (IR) was observed in nuclei of endoneurial cells in 54% (22/41) of vasculitic patients, while specimens from metabolic neuropathies showed less nuclear IR and the difference of mean density of HIF‐1α‐positive nuclei was significant. Two patients with possible vasculitis who showed HIF‐1α‐positive nuclei in endoneurium, were later confirmed to have vasculitis by skin biopsies. Most of the cells expressing HIF were demonstrated to be Schwann cells. There was a trend in the vasculitic patients with early phase nerve damage to display higher endoneurial HIF‐1α‐IR. HIF‐1α may be an immunohistochemical marker for vasculitic neuropathy, especially when the observed section contains no vasculitic lesions. 相似文献
47.
尿激酶溶栓对大鼠局灶性脑缺血基质金属蛋白酶-9表达的影响 总被引:1,自引:1,他引:0
目的研究大鼠局灶性脑缺血后应用尿激酶(urokinase,UK)溶栓对基质金属蛋白酶-9(Matrix metalloproteinase-9,MMP-9)表达的影响,探讨MMP-9在UK溶栓引起的再灌注损伤及出血性转化中的作用。方法将实验动物随机分成3组进行研究(1)UK溶栓组;(2)缺血对照组;(3)假手术组。分别用免疫组织化学方法分析3组缺血后24hMMP-9的表达,对比研究两组MMP-9表达的差异性。结果缺血后24h前两组均有MMP-9的表达,但是UK溶栓组表达的程度明显高于缺血对照组;假手术组无MMP-9的表达。结论(1)缺血能导致MMP- 9的表达。(2)UK溶栓引起MMP-9表达的上调。 相似文献
48.
Previously reported attenuation of skin postural vasoconstriction in women during the luteal menstrual cycle phase may be
due to a progesterone-mediated decrease in myogenic or veno-arteriolar (VAR) mechanisms. Skin perfusion was measured in the
shin and foot dorsum by Laser Doppler Fluxometry during leg dependency that increased vascular transmural pressure below (myogenic
constriction only) and above (myogenic and VAR) the 25 mmHg threshold for activation of the VAR, and during venous distension
to activate the VAR alone (cuff inflation to 50 mmHg). In six young women with normal menstrual cycles, vasoconstrictor responses
to all interventions did not differ between days 7–13 (follicular) and 18–23 (luteal) of the normal menstrual cycle when progesterone
levels were low and at their peak respectively. In eight women taking combined oral contraceptives (OC) and tested during
pill consumption days, reductions in foot skin perfusion were smaller (P = 0.05) than in the luteal phase of the normal cycle for leg dependency below (−36.9 ± 5.2% OC vs. −52.5 ± 7.8% luteal, mean ± S.E.M.)
and above (−43.7 ± 3.4% OC vs. −55.1 ± 4.8% luteal) the VAR threshold, and for venous distension (−53.1 ± 2.6% OC vs. 66.4 ± 5.5%
luteal). In women with normal menstrual cycles, impaired postural vasoconstriction may be confined to those who experience
pre-menstrual symptoms rather than a direct effect of endogenous hormones. Reduced vasoconstriction in the dependent foot
during OC use is consistent with the known vasodilator action of exogenous hormones and its long-term effects 相似文献
49.
50.
头皮针对脑缺血模型大鼠血浆内皮素-1的影响 总被引:4,自引:0,他引:4
目的 :研究头皮针对脑缺血模型大鼠内皮素 - 1 ( ET- 1 )的影响 ,并与电针组比较。方法 :Wistar大鼠 5 0只 ,随机分正常、假手术、模型、电针、头皮针五组 ,每组 1 0只 ,后四组均于造模后 72小时、1 0天、1 5天取血测 ET- 1 ,并与手术后 6小时测定值进行比较 ;前三组不治疗 ,后两组造模后分别用电针与头皮针治疗。观察治疗前后 ET- 1测定值。结果 :神经功能评分 ,术后 1 0天与 1 5天 ,治疗组与模型组有显著性差异 ( P<0 .0 5~ 0 .0 1 ) ,电针组与头皮针组 ET- 1测定值无明显差异。对ET- 1的影响 ,术后 72小时及 1 0天时 ,治疗组 ET- 1明显低于模型组 ( P<0 .0 5 ) ,头皮针组明显低于电针组 ( P<0 .0 5 )。结论 :头皮针可在脑缺血早期就明显降低血浆 ET- 1含量 ,这可能是头皮针减轻脑缺血损伤并促进肢体功能恢复的机制之一。 相似文献