全文获取类型
收费全文 | 2392篇 |
免费 | 181篇 |
国内免费 | 21篇 |
专业分类
耳鼻咽喉 | 49篇 |
儿科学 | 70篇 |
妇产科学 | 35篇 |
基础医学 | 320篇 |
口腔科学 | 287篇 |
临床医学 | 213篇 |
内科学 | 488篇 |
皮肤病学 | 62篇 |
神经病学 | 139篇 |
特种医学 | 145篇 |
外国民族医学 | 1篇 |
外科学 | 181篇 |
综合类 | 50篇 |
预防医学 | 242篇 |
眼科学 | 47篇 |
药学 | 187篇 |
中国医学 | 15篇 |
肿瘤学 | 63篇 |
出版年
2023年 | 17篇 |
2022年 | 35篇 |
2021年 | 77篇 |
2020年 | 59篇 |
2019年 | 86篇 |
2018年 | 103篇 |
2017年 | 68篇 |
2016年 | 79篇 |
2015年 | 98篇 |
2014年 | 117篇 |
2013年 | 129篇 |
2012年 | 158篇 |
2011年 | 142篇 |
2010年 | 117篇 |
2009年 | 83篇 |
2008年 | 98篇 |
2007年 | 110篇 |
2006年 | 78篇 |
2005年 | 65篇 |
2004年 | 55篇 |
2003年 | 43篇 |
2002年 | 53篇 |
2001年 | 32篇 |
2000年 | 44篇 |
1999年 | 43篇 |
1998年 | 58篇 |
1997年 | 46篇 |
1996年 | 44篇 |
1995年 | 28篇 |
1994年 | 44篇 |
1993年 | 34篇 |
1992年 | 23篇 |
1991年 | 13篇 |
1990年 | 16篇 |
1989年 | 28篇 |
1988年 | 26篇 |
1987年 | 25篇 |
1986年 | 18篇 |
1985年 | 19篇 |
1984年 | 17篇 |
1983年 | 16篇 |
1982年 | 19篇 |
1981年 | 12篇 |
1980年 | 19篇 |
1979年 | 9篇 |
1978年 | 8篇 |
1977年 | 18篇 |
1976年 | 11篇 |
1975年 | 10篇 |
1971年 | 5篇 |
排序方式: 共有2594条查询结果,搜索用时 15 毫秒
31.
Pertussis is a globally distributed infectious disease that is a significant cause of morbidity and mortality, especially in infants who are too young to be immunized. This disease is common in childhood, and when it occurs during the first few months of life, it leads to hospitalization and, sometimes, death. Brazil has adopted the strategy of maternal immunization against pertussis in late 2014. This study aims to analyze public data on the disease to determine whether there was an impact on the disease burden following the introduction of the vaccine Tdap in pregnant women and its magnitude. We performed a time-series analysis of the incidence of pertussis between October 2010 and January 2019. We stratified the population of interest into three groups: infants aged less than two months old, infants aged two to six months, and infants aged six months to one year, according to Brazil's vaccination schedule. We found a protective effect of maternal vaccination in all age groups, more prominent on the first group. Before the intervention, infants under two months had a higher risk of getting pertussis in comparison with infants two to six months old (HR 1.15, CI 95%: 1.11–1.19). After the intervention, age under two months is a protective factor compared with two to six months (HR 0.90, CI 95%: 0.82–0.98). The pertussis incidence reduced in all age groups and all Brazil's Regions. 相似文献
32.
Castro DJ Saxton RE Soudant J Calcaterra T Lufkin R Nyerges A Aldinger J Paiva M Anzai Y Chung PS 《Journal of clinical laser medicine & surgery》1994,12(2):65-73
Imaging-guided palliative therapy of recurrent and/or inaccessible head and neck tumors may soon become clinically practical since sensitive and noninvasive monitoring techniques of energy deposition in tissues are now available. Interstitial tumor therapy (ITT) is a technique whereby a source of energy (laser, radiofrequency, ultrasonic, cryoenergy, etc.) is directly applied into tumors at various depths. Recent studies have demonstrated the efficiency of ultrasound (UTZ) and magnetic resonance imaging (MRI) for real and/or "near" real time tumor and vessel identification as well as monitoring and quantifying energy-induced tissue damage. We now report our initial clinical experience with patients in which UTZ and/or MRI-guided ITT techniques were successfully applied for the treatment of recurrent, nonresectable, local, and/or metastatic head and neck carcinomas. Patients were treated on an outpatient basis either in the operating room or in an upgraded specially equipped SIGNA 1.5T MR suite. Most patients tolerated these procedures well and were successfully palliated for periods ranging from 3 months to 5 years posttreatment. The upgrades introduced in a standard MRI suite, the clinical experience, and future perspectives will be reviewed. 相似文献
33.
Nonhereditary p53 mutations in T-cell acute lymphoblastic leukemia are associated with the relapse phase 总被引:2,自引:0,他引:2
We have previously reported that greater than 60% of human leukemic T- cell lines possess mutations in the p53 tumor suppressor gene. To determine whether T-cell acute lymphoblastic leukemia (T-ALL) patient samples possess p53 mutations, we screened peripheral blood-and bone marrow-derived leukemia samples, taken at diagnosis and at relapse, for p53 mutations. Exons 4 through 9 and selected intron regions of the p53 gene were analyzed using polymerase chain reaction-single-strand conformation polymorphism and direct sequencing. p53 mutations were found in 0 of 15 T-ALL diagnosis samples, as compared with 10 of 36 (28%) T-ALL relapse samples. To determine whether p53 mutations play a role in the recurrence (relapse) of T-ALL, two special groups of T-ALL patients were studied: (1) a group of 8 relapse patients whose disease was refractory to chemotherapeutic treatment, and (2) a group of 6 "paired" T-ALL cell samples from patients for whom we possess both diagnosis and relapse samples. Three of 8 relapsed patients (37.5%) whose disease was refractory to the reinduction of remission by chemotherapy possessed missense mutations of the p53 gene. All 3 cases had mutations in exon 5. Among the paired samples, 3 of 6 patients harbored p53 mutations at disease recurrence, but possessed only wild- type p53 alleles at diagnosis. One case had mutation on exon 4, 1 case in exon 5, and 1 case in exon 8 with loss of heterozygosity. These data clearly indicate that recurrence of T-ALL is associated with missense mutations in p53. Our results indicate that (1) mutations of p53 do occur in T-ALL in vivo, and such mutations are associated with the relapse phase of the disease; and (2) p53 mutation is involved in the progression of T-ALL. This conclusion is supported by our observation that the introduction of T-ALL-derived mutant p53 expression constructs into T-ALL cell lines further increases their growth rate in culture, enhances cell cloning in methylcellulose, and increases tumor formation in nude mice. 相似文献
34.
M. Q. Paiva D. Moura M. J. Vaz-da-Silva S. Guimarães 《Naunyn-Schmiedeberg's archives of pharmacology》1994,350(1):28-33
The present study was undertaken to analyse the relationship between postnatal development of vascular 2-adrenoceptor-mediated responses and the content of adrenaline in the adrenal gland and its concentration in plasma. Dog saphenous vein tissue from newborn, two-weeks old and adult animals were either preloaded with 3H-noradrenaline (or 3H-adrenaline) to study prejunctional -adrenoceptor-mediated effects or mounted in organ baths to determine isoprenaline-induced relaxation of preparations contracted by phenylephrine to about 65010 of the maximum. The adrenal glands and samples of blood from the same animals were taken for estimation of adrenaline and noradrenaline.At birth, there were no -adrenoceptor-mediated effects pre- or postjunctionally. At two weeks, while the results at the prejunctional level were not significantly different from those obtained in newborns, at the postjunctional level there was a relaxant response to isoprenaline, which antagonised about 35010 of the previous contraction to 1.75 mol·l–1 phenylephrine. In adults, isoprenaline (50 nmol·l–1) increased by 24% tritium overflow evoked by electrical stimulation of tissues preloaded with 3H-noradrenaline but not that of tissues preloaded with 3H-adrenaline. On the other hand, propranolol (1 mol·l–1) reduced by 21% the overflow of tritium evoked by electrical stimulation of tissues preloaded with 3H-adrenaline but not that of tissues preloaded with 3H-noradrenaline; postjunctionally, the maximal response to isoprenaline antagonised 70% of the previous contraction to 1.75 mol·l–1 phenylephrine.At birth the catecholamine content of the adrenals was relatively low (2.9 ol·g–1) and the adrenaline/noradrenaline ratio was 0.26; two weeks later, the catecholamine content was 14.5 mol·g-1and the adrenaline/noradrenaline ratio was 0.74; in adults, the catecholamine content was 24.5 mol·g–1 and the adrenaline/noradrenaline ratio was 2.3. In plasma, the highest concentration of adrenaline was observed at birth (11.8 nmol·l–1); two weeks later it was 5.5 nmol·l–1 and in adulthood it fell to 3.1 nmol·l–1.On the basis of these results, it is concluded that some link between the postnatal increase in adrenaline adrenal content and the development of 2-adrenoceptor-mediated pre- and postjunctional effects may exist. Additionally it is suggested that circulating adrenaline may trigger the development of 2-adrenoceptor-mediated responses as well as some hypertensive states occurring as a consequence of an overreactivity of the sympathoadrenal system.
Correspondence to: S. Guimarães at the above address 相似文献
35.
A L Guerra A Rossi L M Paiva H K Sato V A Souza P T Sakane E R Baldacci 《Revista de saúde pública》1999,33(4):374-378
OBJECTIVE: A measles outbreak occurred in S. Paulo state, during 1996 and 1997, resulting in 20,921 cases. Forty seven percent of the cases occurred in people between 20 and 29 years of age, and one of the control strategies of the Department of Health was the vaccination of health care workers. The prevalence of antibodies against measles among the hospital pediatricians was investigated. METHODS: One hundred and fifty samples were taken from volunteer pediatricians to test for measles antibodies using ELISA. A questionnaire about their having had measles and the vaccine was filled out. RESULTS: Of the 150 doctors, 122 (81.4%) were female and 28 (18.6%) male, of between 23 and 46 years of age (mean and median 27 years). The majority (98%-147/150) had protective levels of antibodies against measles (>100 UI/ml); 118 (80.3%-118/147) without and 29 (19.7%-29/147) with a history of measles. Only 3 pediatricians (2%-3/150), had negative serology, 2 without and 1 with a history of measles. Out of the 118 without history of measles, 79 (67%-39/118) in spite of the protective level of antibodies against measles, did not know if they, had been vaccinated. Out of the 79 vaccinated pediatricians, 64 (81%-64/79), had been vaccinated 25 years before, and still maintained protective levels of antibodies. Of the 3 doctors with negative serologies only one declared that he had been vaccinated. CONCLUSIONS: Measles seroprevalence among pediatricians of this hospital is high, especially due to preceding vaccination. On the other hand, the 2% of pediatricians with negative serology, in an epidemic situation could constitute a significant population for the acquisition and dissemination of the disease. 相似文献
36.
37.
碱离子水饮用后血小板聚集率的的变化(附30例报告) 总被引:1,自引:0,他引:1
目的:报告30例饮用豪斯牌碱离子水前、后血小板聚集率的变化。方法:饮用碱离子水前、后(2~3月,>3~6月)作比浊法血小板聚集试验,以1分钟、5分钟及5分钟内最大聚集率(Max%)为指标,同时检测部分血粘度指标及凝血因子,并用自动生化仪检测血糖、血脂、主要电解质及部分肝、肾功能。结果:饮碱离子水后,血小板聚集率明显下降,而以疾病组(Max>80%)下降尤为明显,P均<0.001。饮碱离子水后血小板聚集率的下降,部分可能与损伤的血管内皮得到修复有关。主要电解质及部分肝、肾功能无明显异常改变。结论:由于心、脑血管血栓性疾病患者血小板聚集率多明显升高,饮碱离子水后血小板聚集率明显下降,且长期饮用对主要电解质及部分肝、肾功能无明显异常改变,作者认为碱离子水使用方例、安全、有效、价廉,因而对心、脑血管血栓性疾病防治方面可能是一种积极的辅助方法,值得临床进一步探索。 相似文献
38.
1. Angiotensin and bradykinin facilitate the release of noradrenaline from sympathetic nerve terminals and cause positive inotropy in rat isolated atria and ventricles. The effect of bradykinin was enhanced by the ACE inhibitor, ramiprilat. 2. The facilitated release of noradrenaline in rat ventricle by bradykinin was blocked by the beta2-receptor antagonist HOE-140. This response is also reduced by removing the endocardium, suggesting the release of a mediator from the endocardium. 3. The facilitated noradrenaline release by angiotensin II and bradykinin was blocked by the angiotensin receptor antagonist saralasin to the same extent. In contrast, losartan caused only minor blockade in a range of vascular and cardiac tissues. This suggests that angiotensin and bradykinin exert these responses by interacting with a prejunctional receptor different from the established AT1 subtype. 4. These results suggest that bradykinin mediates facilitation of noradrenaline release via the local release of angiotensin onto an atypical AT1 receptor. 相似文献
39.
João Luis Callegari Lopes Izabel Cristina Casanova Myrian C. Garcia de Figueireido Francisco Carlos Nather Wagner E. Paiva Avelar 《Archives of environmental contamination and toxicology》1992,23(3):351-354
The mussel Anodontites trapesialis (Lam, 1819) was used as an indicator of organochlorine pollutants in the Pardo River, located in the municipality of Ribeirão Preto (21° 07S and 47° 45W), State of São Paulo, Brazil.Biological monitoring was performed for one year at the site of a sugar cane grove on the left bank of the river. Forty-three animals were placed in two aluminum enclosures on the river bottom at this site and 4 animals of each enclosure were sacrificed for pesticide analysis at 3-month intervals, each collection corresponding to one season of the year.The animals were found to have been exposed to DDT, lindane, heptachlor, aldrin and dieldrin. Endrin was not detected in any of the analyses.Research supported by Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) and by Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP). 相似文献
40.
Bradykinin potentiating and sensitizing activities of new synthetic analogues of snake venom peptides 总被引:3,自引:0,他引:3
The structural requirements for prolonged residual ("sensitizing") activity in bradykinin-potentiating peptides (BPP's) were investigated through a study of seven synthetic BPP's including three not previously described: [Lys6]-BPP9a, [Gly6]potentiator B, and [Lys6,Gln8]potentiator B. The quantitation of the sensitizing activities in the isolated guinea pig ileum indicated that the structural requirements for bradykinin potentiation and for sensitization were not the same. The most potent sensitizers were potentiator B and [Lys6]-BPP9a. 相似文献