全文获取类型
收费全文 | 29460篇 |
免费 | 1353篇 |
国内免费 | 200篇 |
专业分类
耳鼻咽喉 | 323篇 |
儿科学 | 550篇 |
妇产科学 | 705篇 |
基础医学 | 3403篇 |
口腔科学 | 1523篇 |
临床医学 | 2234篇 |
内科学 | 7940篇 |
皮肤病学 | 443篇 |
神经病学 | 2760篇 |
特种医学 | 1111篇 |
外科学 | 4237篇 |
综合类 | 112篇 |
一般理论 | 7篇 |
预防医学 | 1558篇 |
眼科学 | 433篇 |
药学 | 1618篇 |
中国医学 | 119篇 |
肿瘤学 | 1937篇 |
出版年
2023年 | 175篇 |
2022年 | 419篇 |
2021年 | 806篇 |
2020年 | 457篇 |
2019年 | 632篇 |
2018年 | 821篇 |
2017年 | 575篇 |
2016年 | 697篇 |
2015年 | 804篇 |
2014年 | 1106篇 |
2013年 | 1494篇 |
2012年 | 2284篇 |
2011年 | 2448篇 |
2010年 | 1411篇 |
2009年 | 1250篇 |
2008年 | 2131篇 |
2007年 | 2183篇 |
2006年 | 2011篇 |
2005年 | 2020篇 |
2004年 | 1796篇 |
2003年 | 1556篇 |
2002年 | 1443篇 |
2001年 | 185篇 |
2000年 | 118篇 |
1999年 | 165篇 |
1998年 | 239篇 |
1997年 | 189篇 |
1996年 | 184篇 |
1995年 | 144篇 |
1994年 | 133篇 |
1993年 | 91篇 |
1992年 | 92篇 |
1991年 | 84篇 |
1990年 | 71篇 |
1989年 | 69篇 |
1988年 | 68篇 |
1987年 | 50篇 |
1986年 | 50篇 |
1985年 | 41篇 |
1984年 | 84篇 |
1983年 | 54篇 |
1982年 | 72篇 |
1981年 | 45篇 |
1980年 | 27篇 |
1979年 | 24篇 |
1978年 | 26篇 |
1977年 | 30篇 |
1976年 | 21篇 |
1974年 | 16篇 |
1973年 | 22篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Carla Santos Araújo Roberto Roncon Albuquerque Mónica Moreira Rodrigues Benedita Sampaio Maia Adelino F Leite Moreira Manuel Pestana 《Revista portuguesa de cardiologia》2006,25(4):419-427
INTRODUCTION: The biological activity of the natriuretic peptide (NP) system is dependent on the balance between NP tissue levels and the local expression of their receptors. In the kidney, the natriuretic peptide receptor type A (NPR-A) is the principal receptor mediating NP activity and is mainly expressed in the renal medulla. An increase in circulating NP levels is well documented in chronic renal failure (CRF); however, the renal expression of NPR-A has not been evaluated in this condition. METHODS: Wistar-Han rats were submitted to right nephrectomy plus ablation of both poles of the left kidney (3/4nx; n=27) or were sham operated (Sham; n=22) and followed for up to 26 weeks post surgery. Blood pressure measurements were performed weekly. Two, 10 and 26 weeks after surgery, renal sodium and creatinine excretion were evaluated and the kidneys removed for NPR-A mRNA quantification by real-time PCR. The results of mRNA quantification are expressed in arbitrary units (AU) set as the mean value of the Sham group (Sham=1 AU), after normalization for GAPDH (p<0.05). weeks after surgery) and in elevated fractional sodium excretion (+270%, 26 weeks after surgery). Although sodium intake was similar in 3/4nx and Sham rats, blood pressure was higher in 3/4nx rats and increased progressively throughout the study. This was accompanied by a marked decrease in NPR-A mRNA levels in the renal medulla from 3/4nx animals at 2, 10 and 26 weeks post surgery. Conclusion: In 3/4nx rats, the expression of NPR-A in the renal medulla of the remnant kidney is markedly reduced from 2 weeks up to 26 weeks post surgery. It is suggested that this may contribute to the progressive increase in blood pressure, as well as to the renal fibrosis observed in 3/4nx rats. 相似文献
22.
Roberto Rivera-Luna Marta Zapata-Tarrés Aurora Medina-Sansón Enrique López-Aguilar Ana Niembro-Zúñiga J. Amador Zarco Alfonso Marhx-Bracho Fernando Rueda-Franco Leticia Bornstein-Quevedo 《Child's nervous system》2007,23(5):543-547
Objective The purpose of this study is to analyze clinical aspects and disease-free survival (DFS) in children less than 3 years of
age diagnosed with low-grade astrocytoma.
Methods In a period of 24 years (1980–2004), a total of 43 (5.4%) children were registered with these characteristics. Twenty-three
patients had pilocytic astrocytoma, 18 diffused, and 2 mixed. Thirty-one (72.1%) children had incomplete surgical tumor resection
and 12 (27.9%) had a complete tumor resection. Twelve (27.9%) patients had cranial radiotherapy and 17 (39.5%) received chemotherapy.
Overall survival was recorded in 23 (53%). DFS was 50% at 250 months of follow-up for the whole group. DFS for the supratentorial
group was 60% at 250 months, whereas, for the infratentorial, it was 22% at 120 months (p = 0.008).
Conclusion The only favorable prognostic pattern was the supratentorial presentation. Radiotherapy and chemotherapy did not alter the
outcome. 相似文献
23.
Linda Wang D.D.S. M.S. Ph.D. Lawrence Gonzaga Lopes D.D.S. M.S. Ph.D. Eduardo Bresciani D.D.S. M.S. José Roberto Pereira Lauris D.D.S. M.S. Ph.D. Rafael Francisco Lia Mondelli D.D.S. M.S. Ph.D. Maria Fidela de Lima Navarro D.D.S. Ph.D. 《Special care in dentistry》2004,24(1):28-33
Atraumetic Restorative Treatment (ART) has been adopted around the world to avoid unnecessary extractions, especially in non-industrialized countries The development of specific glass ionomer cements marketed for the ART technique has contributed to the technical success rate. In this study. Ketac-Molara (3M ESPE. Dental Medzn Germany) was used to restore 150 Class I cavities in 118 Brazilian public school children, aged from 7–12 years. At baseline and at subsequent recalls. CPI probes with a ball-end of 0.5 millimeters (mm) were used to assess loss of restorative material, and photographic color transparencies of restorations were made. After six months. 83 patients returned for follow-up examinations, with 71.8% of their restorations designated as acceptable. After three years. 49 patients with 57 ART-restorations were evaluated, with 21.0% of these restorations graded as acceptable Another 29.8% of their restorations had been replaced by more permanent materials. The main objective of the ART technique is tooth retention; this was achieved for 94.7% of the restored teeth in a high caries risk population who returned for recalls. 相似文献
24.
25.
Claude Clément MD Roberto Ruiz MD Bogdan Costa-Foru MD Hubert Nicaise MD 《Annals of vascular surgery》1990,4(3):305-308
Extrinsic compression of the renal artery due to a fibromuscular band originating from the diaphragm was encountered in a 26-year-old patient who had systemic hypertension associated with stenosis and kinking of one of her renal arteries. After surgical decompression, the renal artery assumed a normal expansion with disappearance of hypertension. Six other cases of extrinsic compression of the renal artery have been found in the literature. Surgical treatment is mandatory in all cases because the mechanism that causes the lesion makes percutaneous transluminal angioplasty illusory. 相似文献
26.
Mono- and bi-allelic expression of insulin-like growth factor II gene in human muscle tumors 总被引:4,自引:1,他引:3
Pedone Paolo V.; Tirabosco Roberto; Cavazzana Andrea O.; Ungaro Paola; Basso Giuseppe; Luksch Roberto; Carli Modesto; Bruni Carmelo B.; Frunzio Rodolfo; Riccio Andrea 《Human molecular genetics》1994,3(7):1117-1121
Insulin-like growth factor II (IGF-II) is a mitogen for manycell types and an important modulator of muscle growth and differentiation.IGF-II gene is prevalently expressed during prenatal developmentand its gene activity is regulated by genomic imprinting, inthat the allele inherited from the father is active and theallele inherited from the mother is inactive in most normaltissues. IGF-II expression is activated in several types ofhuman neoplasms and an alteration of IGF-II imprinting has beendescribed in BeckwithWiedemann syndrome and Wilms' tumour.Here we show that monoallelic expression of IGF-II gene is conservedin normal adult muscle tissue whereas two or more copies ofactive IGF-II alleles, arising by either relaxation of imprintingor duplication of the active allele, are found in 9 out of 11(82%) rhabdomyo-sarcomas retaining heterozygosity at 11p15,regardless of the histological subtype. Since IGF-II has beenindicated as an autocrine growth factor for rhabdomyosarcomacells, these findings strongly suggest that acquisition of adouble dosage of active IGF-II gene is an important step forthe initiation or progression of rhabdomyosarcoma tumorigenesis.Among different types of muscle tumors, relaxation of imprintingseems to arise prevalently in rhabdomyosarcomas, since we havedetected only one case of partial reactivation of the maternalIGF-II allele out of 7 lelomyosarcomas tested. 相似文献
27.
28.
Increased incidence of gap junctional coupling between spinal motoneurones following transient blockade of NMDA receptors in neonatal rats 总被引:3,自引:0,他引:3
George Z. Mentis Eugenia Díaz Linda B. Moran Roberto Navarrete 《The Journal of physiology》2002,544(3):757-764
Neonatal rat motoneurones are electrically coupled via gap junctions and the incidence of this coupling declines during postnatal development. The mechanisms involved in this developmental regulation of gap junctional communication are largely unknown. Here we have studied the role of NMDA receptor-mediated glutamatergic synaptic activity in the regulation of motoneurone coupling. Gap junctional coupling was demonstrated by the presence of graded, short latency depolarising potentials following ventral root stimulation, and by the transfer of the low molecular weight tracer Neurobiotin to neighbouring motoneurones. Sites of close apposition between the somata and/or dendrites of the dye-coupled motoneurones were identified as potential sites of gap junctional coupling. Early postnatal blockade of the NMDA subtype of glutamate receptors using the non-competitive antagonist dizocilpine maleate (MK801) arrested the developmental decrease in electrotonic and dye coupling during the first postnatal week. These results suggest that the postnatal increase in glutamatergic synaptic activity associated with the onset of locomotion promote the loss of gap junctional connections between developing motoneurones. 相似文献
29.
G. Bassotti F. Sietchiping Nzepa G. de Roberto M. J. Fischer A. Morelli 《Digestive and liver disease》2004,36(1):78-81
Selective serotonin reuptake inhibitors are frequently employed to treat depression. However, although rarely, coagulation abnormalities have been described following the use of these compounds, and these effects appear to be enhanced by simultaneous use of nonsteroidal anti-inflammatory drugs. We describe a case of reversible symptomatic duodenal compression caused by a retroperitoneal hematoma after ingestion of sertraline and nimesulide. 相似文献
30.
Juan Carlos Gómez-Esteban Juan Jose Zarranz Elena Lezcano Fernando Velasco Roberto Ciordia Idoia Rouco Jose Losada Iker Bilbao 《Movement disorders》2006,21(7):983-988
The aim of this research was to quantify sleep problems in patients suffering from Parkinson's disease by means of the new Parkinson's Disease Sleep Scale (PDSS) and to correlate such problems with the possible influence of current drug treatment. A total of 70 patients (36 men and 34 women) with a diagnosis of Parkinson's disease were enrolled. Their mean age was 69.7 +/- 8.2 years, and duration of disease was 7.4 +/- 4.8 years. All patients completed the PDSS and the Unified Parkinson's Disease Rating Scale (UPDRS Parts I-IV). Drug consumption and doses were registered. The mean score on the PDSS scale was 109.23 +/- 19.75 and on the UPDRS III scale was 25.24 +/- 11.35. The lowest scores were obtained in Item 3 (sleep fragmentation): 5.53 (2.46); and in Item 8 (nocturia): 5.75 (2.91). There was a weak correlation between the PDSS and UPDRS III (cc = -0.355, P = 0.003), PDSS and UPDRS I (cc = -0.272, P = 0.02), and PDSS and UPDRS IV (cc = -0.416, P < 0.001). Motor conditions, mental state, and drug complications influence sleep quality. Although this effect was significant, it was not of a great magnitude. Dopaminergic drugs did not increase daytime sleepiness. As a whole, sleep quality in patients who took dopaminergic agonists did not differ from that of patients who took levodopa in monotherapy. 相似文献