全文获取类型
收费全文 | 26609篇 |
免费 | 1300篇 |
国内免费 | 85篇 |
专业分类
耳鼻咽喉 | 321篇 |
儿科学 | 680篇 |
妇产科学 | 638篇 |
基础医学 | 3438篇 |
口腔科学 | 1637篇 |
临床医学 | 2122篇 |
内科学 | 6454篇 |
皮肤病学 | 530篇 |
神经病学 | 1969篇 |
特种医学 | 532篇 |
外科学 | 3081篇 |
综合类 | 132篇 |
一般理论 | 13篇 |
预防医学 | 3089篇 |
眼科学 | 392篇 |
药学 | 1788篇 |
中国医学 | 150篇 |
肿瘤学 | 1028篇 |
出版年
2023年 | 235篇 |
2022年 | 153篇 |
2021年 | 562篇 |
2020年 | 346篇 |
2019年 | 610篇 |
2018年 | 1086篇 |
2017年 | 652篇 |
2016年 | 669篇 |
2015年 | 816篇 |
2014年 | 861篇 |
2013年 | 1167篇 |
2012年 | 2133篇 |
2011年 | 2371篇 |
2010年 | 1078篇 |
2009年 | 733篇 |
2008年 | 1815篇 |
2007年 | 1905篇 |
2006年 | 1704篇 |
2005年 | 1640篇 |
2004年 | 1427篇 |
2003年 | 1325篇 |
2002年 | 1215篇 |
2001年 | 480篇 |
2000年 | 547篇 |
1999年 | 392篇 |
1998年 | 98篇 |
1997年 | 49篇 |
1996年 | 48篇 |
1995年 | 46篇 |
1994年 | 29篇 |
1993年 | 37篇 |
1992年 | 239篇 |
1991年 | 168篇 |
1990年 | 146篇 |
1989年 | 124篇 |
1988年 | 113篇 |
1987年 | 108篇 |
1986年 | 101篇 |
1985年 | 90篇 |
1984年 | 61篇 |
1983年 | 58篇 |
1979年 | 35篇 |
1975年 | 40篇 |
1974年 | 50篇 |
1973年 | 30篇 |
1971年 | 37篇 |
1970年 | 38篇 |
1969年 | 36篇 |
1968年 | 41篇 |
1967年 | 28篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
Luciana Dias de Oliveira Elsa Regina Justo Giugliani Lílian Córdova do Espírito Santo Maristela Cavalheiro Tamborindeguy Fran?a Enilda Maria Lara Weigert Celina Valderez Feijó Kohler Ana Lúcia de Lourenzi Bonilha 《Journal of human lactation》2006,22(3):315-321
This randomized clinical trial compared frequencies of exclusive breastfeeding and lactation-related problems during the first 30 days among 74 mothers who received a 30-minute counseling session on breastfeeding technique in the maternity ward, and 137 controls. The frequency of exclusive breastfeeding among mothers who had received intervention was similar to controls by 7 days (79.7% vs 82.5%, respectively) and 30 days (60.8% vs 53.3%). There was no difference between groups in the frequency of sore nipples at 7 and 30 days, in breast engorgement and mastitis, and in the quality of breastfeeding technique at 30 days. Therefore, a single intervention at maternity was not sufficient to improve breastfeeding technique, increase exclusive breastfeeding rates, and reduce the incidence of breastfeeding problems during the first month. 相似文献
72.
Guilherme Santoro-Lopes Erika Ferraz de Gouvêa Rodrigo Carreira M Monteiro Rodrigo Castelo Branco José Rodolfo Rocco Márcia Halpern Adriana Lúcia Pires Ferreira Elaine Gama Pessoa de Araújo Samanta T Basto Vinicius Gomes Silveira Joaquim Ribeiro-Filho 《Liver transplantation》2005,11(2):203-209
Methicillin-resistant Staphylococcus aureus (MRSA) is a frequent cause of infection after orthotopic liver transplantation (OLT). Colonization with MRSA is associated with a higher risk of infection. Previous studies have shown a high prevalence of MRSA colonization among OLT candidates. However, the risk of colonization with MRSA after OLT is still unclear. The objective of this study was to estimate the incidence and the factors associated with colonization with MRSA after OLT. This was a prospective cohort study including patients submitted to OLT between the years 2000 and 2002. Surveillance cultures of nasal swab specimens were performed within the 1st 72 hours of hospital admission and, subsequently, on weeks 2, 6, 13, and 26. Patients whose baseline cultures revealed nasal carriage of MRSA were excluded. A total of 60 patients were included in the study. The median follow-up was 72 days. A total of 9 patients (15%) became colonized. In multiple logistic regression analyses, the use of a urinary catheter for > or =5 days (P = .006), postoperative bleeding at the surgical site (P = .009), and preoperative use of fluoroquinolones (P = .08) were associated with a higher risk of colonization. Patients without any of these risk factors did not become colonized. In conclusion, nasal carriage of MRSA is frequently acquired after OLT. Periodic postoperative screening for MRSA carriage should be an integral component in programs designed to reduce nosocomial MRSA transmission in these patients. Further studies are needed to set up and validate a predictive model that could allow targeting postoperative screening to high-risk OLT recipients. 相似文献
73.
74.
Ana María Fortuna Marco Balleza Núria Calaf Mercedes González Teresa Feixas Pere Casan 《Archivos de bronconeumologia》2009,45(3):143-147
Nitric oxide (NO) production has been described using a 2-compartment model for the synthesis and movement of NO in both the alveoli and the airways. The alveolar concentration of NO (CaNO), an indirect marker of the inflammatory state of the distal portions of the lung, can be deduced through exhalation at multiple flow rates. Our objective was to determine reference values for CaNO. The fraction of exhaled NO (FeNO) was measured in 33 healthy individuals at a rate of 50 mL/s; the subjects then exhaled at 10, 30, 100, and 200 mL/s to calculate CaNO. A chemiluminescence analyzer (NIOX Aerocrine) was used to perform the measurements. The mean (SD) FeNO was 15 (6) ppb. The mean CaNO was 3.04 (1.30) ppb. These values of CaNO measured in healthy individuals will allow us to analyze alveolar inflammatory behavior in respiratory and systemic processes. 相似文献
75.
76.
Marcos Barbosa-Ferreira Maria Lúcia Zaidan Dagli Paulo César Maiorka Silvana Lima Górniak 《Food and chemical toxicology》2005,43(4):497-503
Senna occidentalis (So) is a weed that grows in pastures along fences and in fields cultivated with cereals such as corn and soybean, and many reports have been showing intoxication with this plant in different animal species. It is also used in many medicinal purposes. The objective of the present study was to better evaluate the toxic effects of prolonged administration of So seeds to rats. Forty male Wistar rats were divided into four groups of 10 animals each, three of them respectively fed rations containing 1%, 2% and 4% So seeds, and the last one (control) fed commercial ration for a period of 2 weeks. Fourteen rats were also used in a pair-feeding (PF) experiment. The rats of the experimental groups showed lethargy, weakness, recumbency, depression and emaciation. Two rats of the 4% group and two of the PF group died during the experiment. Histopathological study showed fiber degenerations in the skeletal (Tibial, pectoral and diaphragm) and cardiac muscles. In the liver parenchyma, was observed vacuolar degeneration and, in the kidney, mild nefrosis in the proximal convoluted tubules. All of these alterations occurred in a dose-dependent fashion. Moderate to severe degeneration and spongiosis in the central nervous system, especially in cerebellum. Electron microscopy revealed mitochondrial lesions in all analyzed tissues. 相似文献
77.
78.
79.
This study compared the frequency of factors and diseases that contribute to the risks of oral contraceptive use among current users and non-users of oral contraception in order to evaluate the users' awareness of factors associated with complications during oral contraceptive use. Data from 5317 current users and 8863 non-users in the state of São Paulo, Brazil, were collected using questionnaires requesting information on the following variables: use of oral contraceptives, age, weight, smoking status, and the presence or history of hypertension, diabetes, cardiopathies, painful varicose veins, and epilepsy. Half of the users had some risk factors, and 17.4% were at high risk of complications from oral contraceptive use. Risk factors and diseases which appeared to be poorly known by the population as increasing the risk of oral contraceptive use were smoking, hypertension and painful varicose veins. Only a small percentage of the population appeared to know that these diseases and factors could increase the risk of health problems during oral contraceptive use. The results suggest a lack of information among users and providers on factors which are associated with an increased risk of health problems during use of oral contraceptives.
Resumen Este estudio comparó la frecuencia de factores y enfermedades que contribuyen al riesgo de los anticonceptivos orales (AO) entre usuarias y no usuarias corrientes de anticonceptivos orales a fin de evaluar el grado de conocimiento entre las usuarias de los factores asociados con complicaciones durante el uso de AO. Se recopilaron datos de 5317 usuarias y 8863 no usuarias corrientes del Estado de S@o Paulo, Brasil, utilizando cuestionarios en los que se solicitabe información acerca de las siguientes variables: uso de AO, edad, peso, fumadora/no fumadora y la presencia o historia de hipertensión, diabetes, cardiopatías, várices dolorosas y epilepsia. La mitad de las usuarias tenían algunos factores de riesgo y el 17,4% de ellas corrían un alto riesgo de complicaciones por el uso de anticonceptivos orales. Los factores de riesgo y enfermedades que parecían ser poco conocidos por la población como tendientes a aumentar el riesgo del uso de anticonceptivos orales eran el fumar, la hipertensión y las várices dolorosas. Sólo un pequeño porcentaje de la población parecía saber que estas enfermedades y factores podían aumentar el riesgo de problemas de salud durante el uso de anticonceptivos orales. Los resultados sugieren una falta de información de las usuarias y proveedores con respecto a factores que están asociados con un riesgo mayor de problemas de salud durante el uso de anticonceptivos orales.
Resumé Pour évaluer dans quelle mesure les utilisatrices et non utilisatrices de contraceptifs oraux sont sensibilisées aux facteurs associés à des complications, cette étude a comparé la fréquence des facteurs et des maladies qui contribuent au risque que présente l'utilisation de ces contraceptifs. Dans l'Etat de Sao Paulo (Brésil), des données ont été recueillies auprès de 5317 utilisatrices et 8863 non utilisatrices, au moyen de questionnaires demandant des renseignements concernant les variables suivantes: utilisation de contraceptifs oraux, âge, poids, tabagisme, présence ou antécédents d'hypertension, diabète, cardiopathies, varices douloureuses et épilepsie. La moitié des utilisatrices présentaient certains facteurs de risque et 17,4% des facteurs de risque élevé de complications résultant de l'utilisation de contraceptifs oraux. Les facteurs de risque et les maladies dont la population semblait mal connaître l'effet d'augmentation des risques qu'entrîne l'ingestion de contraceptifs oraux étaient le tabagisme, l'hypertension et les varices douloureuses. Un faible pourcentage seulement de la population paraissait savoir que ces maladies et facteurs pouvaient accroître les risques de problèmes de santé durant l'utilisation des contraceptifs oraux. Les résultats suggèrent que les utilisatrices et les pourvoyeurs des services de contraception ne sont pas suffisamment informés des facteurs associés à un risque accru de problèmes de santé durant l'utilisation des contraceptifs oraux.相似文献
80.
S O'Núnáin N J Linker J F Sneddon N M Debbas A J Camm D E Ward 《British heart journal》1992,67(1):67-71
OBJECTIVE--To assess the effects of low energy ablation of the substrate for atrial flutter. DESIGN--Initial retrospective analysis of patients undergoing low energy ablation of the atrioventricular node for refractory atrial flutter (group 1) was followed by a prospective assessment of low energy ablation in the posterio-inferior right atrium for the same condition (group 2). SETTING--Tertiary referral centre for management of cardiac arrhythmias. PATIENTS--Seven men (aged 50-67 years) with refractory atrial flutter. INTERVENTIONS--Multiple (3-10) low energy DC shocks with a cumulative energy of 100-245 J in the region of the atrioventricular node in group 1 and 12-15 low energy DC shocks (cumulative energy 110-235 J) guided by the anatomical landmarks of the triangle of Koch and applied directly to the atrial wall. MAIN OUTCOME MEASURE--Freedom from recurrence of atrial flutter. RESULTS--In group 1 despite initial complete atrioventricular block in three patients, atrioventricular conduction had resumed in all by one month. All four, however, were in sinus rhythm at follow up six to 13 months later. Two of the three patients in group 2 were free of atrial flutter at follow up three to four months after ablation. CONCLUSION--Ablation of the atrial flutter substrate with low energy DC shocks is feasible. Precise electrophysiological mapping is not necessary. 相似文献