全文获取类型
收费全文 | 7108篇 |
免费 | 494篇 |
国内免费 | 25篇 |
专业分类
耳鼻咽喉 | 152篇 |
儿科学 | 222篇 |
妇产科学 | 487篇 |
基础医学 | 924篇 |
口腔科学 | 151篇 |
临床医学 | 590篇 |
内科学 | 1727篇 |
皮肤病学 | 210篇 |
神经病学 | 588篇 |
特种医学 | 163篇 |
外科学 | 978篇 |
综合类 | 25篇 |
一般理论 | 1篇 |
预防医学 | 515篇 |
眼科学 | 97篇 |
药学 | 398篇 |
中国医学 | 22篇 |
肿瘤学 | 377篇 |
出版年
2023年 | 31篇 |
2022年 | 85篇 |
2021年 | 207篇 |
2020年 | 96篇 |
2019年 | 229篇 |
2018年 | 276篇 |
2017年 | 151篇 |
2016年 | 151篇 |
2015年 | 172篇 |
2014年 | 255篇 |
2013年 | 310篇 |
2012年 | 376篇 |
2011年 | 438篇 |
2010年 | 286篇 |
2009年 | 269篇 |
2008年 | 382篇 |
2007年 | 467篇 |
2006年 | 398篇 |
2005年 | 404篇 |
2004年 | 336篇 |
2003年 | 281篇 |
2002年 | 298篇 |
2001年 | 216篇 |
2000年 | 263篇 |
1999年 | 188篇 |
1998年 | 62篇 |
1997年 | 35篇 |
1996年 | 34篇 |
1995年 | 28篇 |
1994年 | 36篇 |
1993年 | 29篇 |
1992年 | 102篇 |
1991年 | 83篇 |
1990年 | 95篇 |
1989年 | 73篇 |
1988年 | 88篇 |
1987年 | 58篇 |
1986年 | 56篇 |
1985年 | 31篇 |
1984年 | 34篇 |
1983年 | 18篇 |
1982年 | 12篇 |
1979年 | 15篇 |
1978年 | 10篇 |
1977年 | 15篇 |
1976年 | 11篇 |
1975年 | 14篇 |
1974年 | 24篇 |
1973年 | 22篇 |
1972年 | 17篇 |
排序方式: 共有7627条查询结果,搜索用时 15 毫秒
61.
To investigate the physiological role of the delta-opioid receptor during the preweanling period, we have studied the effects of chronic (daily injections from birth to postnatal day 19) and acute treatments with the selective delta-antagonist naltrindole (1 mg/kg), on behavioural and nociceptive responses in 20-day old male rats. Behavioural testing was performed using an open field paradigm. Acute naltrindole induced significant decreases in external and total ambulation (horizontal activity) and rearing behaviour (vertical activity), as well as a significant increase in grooming frequency. In animals chronically treated with naltrindole there was an increase in total ambulation one day after the discontinuation of the treatment. In a test of nociception (tail immersion) no significant effect of chronic naltrindole treatment on baseline latencies or of acute naltrindole on latency quotients (post-treatment latency/pre-treatment latency) were found. However, chronic naltrindole administration significantly decreased the latency quotients. The results show that the delta-opioid receptor participates in the tonic regulation of motor activity during the preweanling period and might be involved in certain aspects of stress responsiveness. 相似文献
62.
Replenishment of glutathione levels improves mucosal function in experimental acute colitis 总被引:14,自引:0,他引:14
Ardite E Sans M Panés J Romero FJ Piqué JM Fernández-Checa JC 《Laboratory investigation; a journal of technical methods and pathology》2000,80(5):735-744
Because reactive oxygen species (ROS) have been implicated as mediators of inflammatory bowel disease (IBD), the purpose of the present work was to determine the functional role of mucosal GSH in the trinitrobenzenesulfonic acid in 50% ethanol (TNBS+ethanol)-induced colitis in rats. Mucosal samples were taken to evaluate the temporal relationship between the extent of injury, the levels of glutathione (GSH) during acute colitis induced by TNBS+ethanol, and the effect of N-acetylcysteine (NAC) administration. In vitro assays revealed the interaction of TNBS with GSH leading to the almost instantaneous disappearance of GSH, while the reductive metabolism of TNBS by GSSG reductase generated ROS. Mucosal samples from TNBS+ethanol-treated rats indicated a direct correlation between GSH depletion and injury detected as soon as 30 minutes after TNBS+ethanol administration that persisted 24 hours post treatment. Although, short term depletion of mucosal GSH per se by diethylmaleate did not result in mucosal injury, the oral administration of NAC (40 mM) 4 hours after TNBS+ethanol treatment increased GSH stores (2-fold), decreasing the extent of mucosal injury (60-70%) examined at 24 hours post treatment. However, an equimolar dose of dithiothreitol failed to increase GSH levels and protect mucosa from TNBS+ethanol-induced injury. Interestingly, GSH levels in TNBS+ethanol-treated rats recovered by 1-2 weeks, an effect that was accounted for by an increase of gamma-glutamylcysteine synthetase (gamma-GCS) activity due to an induction of gamma-GCS-heavy subunit chain mRNA. Thus, TNBS promotes two independent mechanisms of injury, GSH depletion and ROS generation, both being required for the manifestation of mucosal injury as GSH limitation renders intestine susceptible to the TNBS-induced ROS overgeneration. Accordingly, in vivo administration of NAC attenuates the acute colitis through increased mucosal GSH levels, suggesting that GSH precursors may be of relevance in the acute relapse of IBD. 相似文献
63.
The identification of tyrosine as a common key residue in unrelated H-2Kd restricted antigenic peptides. 总被引:5,自引:0,他引:5
J L Maryanski P Romero A Van Pel T Boon F R Salemme J C Cerottini G Corradin 《International immunology》1991,3(10):1035-1042
We have compared the activity of several Kd- or Ld-restricted antigenic peptides as competitors in a functional competition assay using cytolytic T lymphocyte (CTL) clones. All of four unrelated Kd-restricted peptides tested could compete with each other but not with the Ld-restricted peptide P91A-. 12-24 (P91A). Moreover, the P91A peptide failed to compete with the four Kd-restricted peptides. In contrast, another Ld-restricted peptide [mouse cytomegalovirus (MCMV) pp89 167-176] could clearly compete with both Kd- and Ld-restricted peptides. The comparison of a series of modified MCMV pp89 peptides suggested that distinct structural features allow the interaction of the peptide with the two different MHC class I molecules. We showed previously that the competitor activity of two different Kd-restricted antigenic peptides was reduced substantially upon Ala substitution of the single Tyr residues present in these peptides. We now show a similar effect for two additional Kd-restricted peptides. Our results thus suggest that Tyr may function as an 'anchor' residue for many antigenic peptides that bind to the Kd molecule. Molecular modeling of the presumed antigen-binding site of the Kd molecule revealed the presence of two deep cavities that may be involved in binding peptide amino acid side chains. A model illustrating one possible interaction of a Tyr-containing peptide with the Kd molecule is presented. 相似文献
64.
Turell MJ O'Guinn ML Navarro R Romero G Estrada-Franco JG 《Journal of medical entomology》2003,40(3):306-310
Experimental studies evaluated the vector competence of Ochlerotatus taeniorhynchus (Wiedemann), Culex cancer Theobald, Culex pseudes (Dyar and Knab), Culex taeniopus Dyar and Knab, and a Culex (Culex) species, probably Culex quinquefasciatus Say, and Culex nigripalpus Theobald from Chiapas, Mexico, and Tocoa, Honduras, for epizootic (IC) and enzootic (IE) strains of Venezuelan equine encephalomyelitis (VEE) virus. Culex pseudes was highly susceptible to infection with both the IC and IE strains of VEE (infection rates >78%). Patterns of susceptibility to VEE were similar for Oc. taeniorhynchus collected in Mexico and Honduras. Although Oc. taeniorhynchus was highly susceptible to the epizootic IC strains (infection rates > or = 95%, n = 190), this species was less susceptible to the enzootic IE strain (infection rates < or = 35%, n = 233). The Culex (Culex) species were refractory to both subtypes of VEE, and none of 166 contained evidence of a disseminated infection. Virus-exposed Cx. pseudes that refed on susceptible hamsters readily transmitted virus, confirming that this species was an efficient vector of VEE. Although Oc. taeniorhynchus that fed on hamsters infected with the epizootic IC strain transmitted VEE efficiently, only one of six of those with a disseminated infection with the enzootic IE virus that fed on hamsters transmitted virus by bite. These data indicate that Cx. pseudes is an efficient laboratory vector of both epizootic and enzootic strains of VEE and that Oc. taeniorhynchus could be an important vector of epizootic subtypes of VEE. 相似文献
65.
Montserrat Plana Odette Vias Oscar de la Calle-Martin Francisco Lozano Julia Ingls-Esteve Matilde Romero Jos Alberola-Ila Jordi Yagüe Ramn Vilella Jordi Vives 《European journal of immunology》1991,21(4):1085-1088
The ability of the 134-2C2 monoclonal antibody (mAb; CD26) to transmit an activation signal and to affect T cell proliferation has been studied. The 134-2C2 mAb, although not being mitogenic by itself, is able to increase the proliferation of purified T cells in the presence of exogenous interleukin 2 (IL2) or phorbol 12-myristate 13-acetate (PMA). No effect of our mAb was observed on the proliferation of T cells induced by other stimuli such as Sepharose-bound CD3 mAb, phytohemagglutinin or calcium ionophore. Since the co-stimulatory effect of 134-2C2 mAb on PMA-induced T cell proliferation was strongly inhibited by an anti-Tac antibody, its involvement on the IL2/IL2 receptor pathway was investigated. An increased IL2 secretion in T cells cultured with PMA plus 134-2C2 mAb was observed and Northern blot analysis showed that the mAb 134-2C2 acts synergistically with PMA favoring the induction of both IL2 and interferon-γ mRNA synthesis, as well as the enhancement of IL2 receptor and transferrin receptor mRNA expression. Studies on mechanisms implicated in signal transduction showed that 134-2C2 mAb modifies neither intracellular calcium levels nor phosphoinositide breakdown. Additionally, no effect was exerted on protein kinase C translocation. These data suggest that the CD26 antigen is involved in T cell activation in an IL2/IL2 receptor-dependent pathway. 相似文献
66.
Mohammad Abumayyaleh Iván J. Núñez Gil Ibrahim El-Battrawy Vicente Estrada Víctor Manuel Becerra-Muñoz Alvaro Aparisi Inmaculada Fernández-Rozas Gisela Feltes Ramón Arroyo-Espliguero Daniela Trabattoni Javier López-País Martino Pepe Rodolfo Romero Diego Raúl Villavicencio García Carloalberto Biole Thamar Capel Astrua Charbel Maroun Eid Emilio Alfonso Ibrahim Akin 《Obesity research & clinical practice》2021,15(3):275-280
BackgroundObesity has been described as a protective factor in cardiovascular and other diseases being expressed as ‘obesity paradox’. However, the impact of obesity on clinical outcomes including mortality in COVID-19 has been poorly systematically investigated until now. We aimed to compare clinical outcomes among COVID-19 patients divided into three groups according to the body mass index (BMI).MethodsWe retrospectively collected data up to May 31st, 2020. 3635 patients were divided into three groups of BMI (<25 kg/m2; n = 1110, 25?30 kg/m2; n = 1464, and >30 kg/m2; n = 1061). Demographic, in-hospital complications, and predictors for mortality, respiratory insufficiency, and sepsis were analyzed.ResultsThe rate of respiratory insufficiency was more recorded in BMI 25?30 kg/m2 as compared to BMI < 25 kg/m2 (22.8% vs. 41.8%; p < 0.001), and in BMI > 30 kg/m2 than BMI < 25 kg/m2, respectively (22.8% vs. 35.4%; p < 0.001). Sepsis was more observed in BMI 25?30 kg/m2 and BMI > 30 kg/m2 as compared to BMI < 25 kg/m2, respectively (25.1% vs. 42.5%; p = 0.02) and (25.1% vs. 32.5%; p = 0.006). The mortality rate was higher in BMI 25?30 kg/m2 and BMI > 30 kg/m2 as compared to BMI < 25 kg/m2, respectively (27.2% vs. 39.2%; p = 0.31) (27.2% vs. 33.5%; p = 0.004). In the Cox multivariate analysis for mortality, BMI < 25 kg/m2 and BMI > 30 kg/m2 did not impact the mortality rate (HR 1.15, 95% CI: 0.889?1.508; p = 0.27) (HR 1.15, 95% CI: 0.893?1.479; p = 0.27). In multivariate logistic regression analyses for respiratory insufficiency and sepsis, BMI < 25 kg/m2 is determined as an independent predictor for reduction of respiratory insufficiency (OR 0.73, 95% CI: 0.538?1.004; p = 0.05).ConclusionsHOPE COVID-19-Registry revealed no evidence of obesity paradox in patients with COVID-19. However, Obesity was associated with a higher rate of respiratory insufficiency and sepsis but was not determined as an independent predictor for a high mortality. 相似文献
67.
68.
Carlos Jiménez Romero Laura Alonso Murillo Paula Rioja Conde Alberto Marcacuzco Quinto Óscar Caso Maestro Anisa Nutu Isabel Pérez Moreiras Iago Justo Alonso 《Cirugía espa?ola》2021,99(6):440-449
IntroductionThere is controversy regarding the ideal pancreaticojejunostomy technique after pancreaticoduodenectomy. Many authors consider the external Wirsung stenting technique to be associated with a low incidence of fistula, morbidity and mortality. We analyse our experience with this technique.Patients and methodsA retrospective analysis of the morbidity and mortality of a series of 80 consecutive patients who had been treated surgically over a 6.5-year period for pancreatic head or periampullary tumors, performing pancreaticoduodenectomy and pancreaticojejunostomy with external Wirsung duct stenting.ResultsMean patient age was 68.3 ± 9 years, and the resectability rate was 78%. The texture of the pancreas was soft in 51.2% of patients and hard in 48.8%. Pylorus-preserving resection was performed in 43.8%. Adenocarcinoma was the most frequent tumor (68.8%), and R0 was confirmed in 70% of patients. Biochemical fistula was observed in 11.2%, pancreatic fistula grade B in 12.5% and C in 2.5%, whereas the abdominal reoperation rate was 10%. Median postoperative hospital stay was 16 days, and postoperative and 90-day mortality was 2.5%. Delayed gastric emptying was observed in 36.3% of patients, de novo diabetes in 12.5%, and exocrine insufficiency in 3. Patient survival rates after 1, 3 and 5 years were 80.2, 53.6 and 19.2%, respectively.ConclusionsAlthough our low rates of postoperative complications and mortality using external Wirsung duct stenting coincides with other more numerous recent series, it is necessary to perform a comparative analysis with other techniques, including more cases, to choose the best reconstruction technique after pancreaticoduodenectomy. 相似文献
69.
Francisco A. Ferri Joel S. Frieder David Gutierrez Blanco David Romero Funes Camila Ortiz Gomez Emanuele Lo Menzo Samuel Szomstein Raul J. Rosenthal 《Surgery for obesity and related diseases》2021,17(2):284-291
BackgroundSleeve gastrectomy (SG) has become the most prevalent bariatric-metabolic surgical approach in the United States. Its popularity among surgeons and patients is mainly due to a better safety profile and less overall morbidity, with broad benefits from a systemic and metabolic perspective.ObjectiveComprehensively describe the short-term multiorgan metabolic effects of rapid weight loss after SG.SettingAcademic hospital, United States.MethodsWe retrospectively reviewed the charts of patients that underwent SG at our institution between 2012 and 2016. We analyzed the required variables to calculate multiple risk scores, such as cardiovascular, hypertension, and diabetes risk scores. Furthermore, the renal and hepatic functions and the metabolic and hematologic profiles were assessed at 12 months of follow-up.ResultsA total of 1002 patients were included in the analysis. The percentage of excess body mass index loss was, on average, 65% at 12 months of follow-up. We observed a positive cardio-renal-hepatic improvement, demonstrated by a substantial reduction of the 10-year cardiovascular risk. We noticed an improvement of renal function, which was more significant in chronic kidney disease (stage ≥2), and a significant improvement on liver function tests (measured by decreased aspartate aminotransferase and alanine transaminase) at 12 months of follow-up. Our data also show a positive impact on decreasing the risk of developing hypertension and type 2 diabetes. There was a positive impact on the lipid profile, with the exception of low-density lipoprotein.ConclusionThere are significant short-term benefits on multiorgan metabolic parameters after rapid weight loss in severely obese patients undergoing sleeve gastrectomy. 相似文献