全文获取类型
收费全文 | 7753篇 |
免费 | 508篇 |
国内免费 | 12篇 |
专业分类
耳鼻咽喉 | 160篇 |
儿科学 | 347篇 |
妇产科学 | 198篇 |
基础医学 | 1045篇 |
口腔科学 | 380篇 |
临床医学 | 546篇 |
内科学 | 1789篇 |
皮肤病学 | 192篇 |
神经病学 | 562篇 |
特种医学 | 311篇 |
外科学 | 1044篇 |
综合类 | 49篇 |
预防医学 | 730篇 |
眼科学 | 94篇 |
药学 | 449篇 |
中国医学 | 44篇 |
肿瘤学 | 333篇 |
出版年
2023年 | 61篇 |
2022年 | 113篇 |
2021年 | 239篇 |
2020年 | 122篇 |
2019年 | 209篇 |
2018年 | 279篇 |
2017年 | 196篇 |
2016年 | 181篇 |
2015年 | 206篇 |
2014年 | 268篇 |
2013年 | 351篇 |
2012年 | 460篇 |
2011年 | 505篇 |
2010年 | 361篇 |
2009年 | 264篇 |
2008年 | 405篇 |
2007年 | 386篇 |
2006年 | 360篇 |
2005年 | 369篇 |
2004年 | 337篇 |
2003年 | 291篇 |
2002年 | 259篇 |
2001年 | 193篇 |
2000年 | 223篇 |
1999年 | 194篇 |
1998年 | 89篇 |
1997年 | 73篇 |
1996年 | 63篇 |
1995年 | 73篇 |
1994年 | 65篇 |
1993年 | 76篇 |
1992年 | 96篇 |
1991年 | 69篇 |
1990年 | 86篇 |
1989年 | 88篇 |
1988年 | 74篇 |
1987年 | 66篇 |
1986年 | 55篇 |
1985年 | 55篇 |
1984年 | 35篇 |
1983年 | 29篇 |
1979年 | 24篇 |
1978年 | 22篇 |
1977年 | 19篇 |
1976年 | 33篇 |
1975年 | 25篇 |
1974年 | 23篇 |
1973年 | 23篇 |
1971年 | 21篇 |
1970年 | 19篇 |
排序方式: 共有8273条查询结果,搜索用时 15 毫秒
71.
IMPLICATIONS: Laparoscopic cholecystectomy is a very common surgical procedure, and vascular injuries account for one third of major complications during this surgery. We describe an unusual presentation of an abdominal aorta injury. 相似文献
72.
García-Yuste M Matilla JM Alvarez-Gago T Duque JL Heras F Cerezal LJ Ramos G 《The Annals of thoracic surgery》2000,70(1):258-263
BACKGROUND: This study examines the experience of the Spanish Multicenter Study of Neuroendocrine Tumors of the Lung through the clinical data and behavior of patients treated for this pathologic process. METHODS: From 1980 to 1997, 361 cases of neuroendocrine carcinomas (NEC) were treated surgically. Patients were enrolled in a protocol using the pathologic and follow-up reports. According to Dreslers' criteria, the cases were segregated into grade 1 (typical carcinoid), grade 2 (atypical carcinoid), grade 3 large cell type, and grade 3 small cell type. Several variables were reviewed in all patients. Statistical analysis was performed to determine whether clinical characteristics and differentiation were associated with significant differences in the prognosis. RESULTS: A total of 261 cases of NEC were identified with grade 1, 43 with grade 2, and with grade 3: 22 of large and 35 of small cells. Five-year survival for different grades was as follows: grade 1, 96%; 2, 72%; 3 large cell type, 21%; and 3 small cell type, 14%. When a comparative analysis between typical and atypical carcinoids was performed a significant difference for mean age, tumor size, nodal metastases, and recurrence was observed. However, female sex, nodal metastases, and recurrence rate differed between atypical carcinoids and grade 3 NEC of large cells. A difference in recurrence rate was found between patients with both types of grade 3 NEC. CONCLUSIONS: The progressive deterioration of tumor organization highlights that neuroendocrine tumors constitute a continuous spectrum. A careful observation of pathologic findings is necessary to individualize their prognostic factors. 相似文献
73.
Patrícia Gon?alves Pinheiro Gilvandete Maria Pinheiro Santiago Francisco Erivaldo Freitas da Silva Ana Carolina Justino de Araújo Cícera Rejane Tavares de Oliveira Priscilla Ramos Freitas Janaína Esmeraldo Rocha JoséBezerra de Araújo Neto Maria Milene Costa da Silva Saulo Relison Tintino Irwin Rose Alencar de Menezes Henrique Douglas Melo Coutinho JoséGalberto Martins da Costa 《Asian Pacific Journal of Tropical Biomedicine》2021,(9):405-413
Objective: To evaluate the inhibitory activity of ferulic acid and four of its esterified derivatives (methyl, ethyl, propyl, and butyl) against resistance mech... 相似文献
74.
Rita M. R. da Silva Cludio F. G. Farias Ana G. A. Ramos Isabel M. R. Mesquita 《Journal of Sports Science and Medicine》2022,21(2):153
This study aimed to examine how a novice Physical Education teacher unfolded her pedagogical practice as a facilitator of learning during a hybrid Sport Education/Step-Game-Approach volleyball season; and to investigate students’ perceptions about their lived learning experiences and active involvement in building their own learning process. For this purpose, an insider action-research design was implemented throughout one school term (20 lessons of 45 minutes each in total). Twenty-five students (aged between16 and17 years old), enrolled in the 12th grade at a Portuguese high school took part in this investigation. The novice teacher, who held two years of professional experience, assumed the dual role of teacher-researcher, facilitating an in-depth understanding of the complexity featuring of the teaching-learning process. Qualitative data were collected using multiple data sources (i.e., teacher’s lesson plans and field diary, and student’s focus-group interviews), and analyzed using a hybrid approach of inductive and deductive thematic analysis. The results revealed that the use of this hybrid season helped the teacher to act as facilitator of learning, namely by: (i) using two student-centered models with unique internal structures and functionalities, (ii) increasing the level of responsibility taken by students for their own learning experiences, (iii) adapting the lesson plans to students’ individual needs, and (iv) combining a more supportive intervention with the use of more indirect teaching strategies. Together, these strategies seemed to prompt students’ autonomy and sense of active control of the class activities, the development of students’ abilities and volleyball-based knowledge, leading them to be more interested and engaged in Physical Education. In conclusion, the alliance between the student-centered environment (Sport Education) and the specificity of the content subject-knowledge (Step-Game Approach for non-invasion games) seems to have allow the novice teacher to adjust her pedagogical intervention as facilitator of learning to students’ individual learning needs. Key points
- The alliance between the Sport Education and the Step-Game Approach allows the novice teacher to adjust her pedagogical intervention as facilitator of learning to students’ individual learning needs.
- Students perceived that they developed their autonomy and sense of active control of the class activities, their abilities and volleyball-based knowledge, which made them more interested and engaged in PE.
- Future studies should consider longitudinal AR designs and video-audio as a complementary data source data.
- PETE and professional development programs should be more focused on developing teacher’s ability to game design, to use effective questioning and gradually to empower students to assume an active role over their learning experiences. Also, offer school placement training and postgraduate professional practice based on student-centered approaches.
75.
Deoxynivalenol (DON) remains one of the most concerning mycotoxins produced by the Fusarium genus due to the wide occurrence in highly consumed cereal-based food and its associated toxicological effects. Previous studies conducted in Spain and other European countries suggested that some vulnerable groups such as children could be exceeding the tolerable daily intakes. Thus, the aim of this study was to conduct a comprehensive and updated dietary exposure assessment study in Spain, with a specific analysis in the region of Catalonia. Cereal-based food samples collected during 2019 were analysed using liquid chromatography coupled to tandem mass spectrometry for multi-mycotoxin detection including DON and its main metabolites and derivatives. Consumption data were gathered from the nation-wide food surveys ENALIA and ENALIA2 conducted in Spain, and a specific survey conducted in Catalonia. The data were combined using deterministic and semi-parametric probabilistic methods. The results showed that DON was widely present in cereal-based food highly consumed in Spain and the Catalonia region. Exposure to DON among the adult population was globally low; however, among infants aged 3–9 years, it resulted in the median of 192 ng/kg body weight/day and the 95th percentiles of 604 ng/kg body weight/day, that would exceed the most conservative safety threshold for infants. Bread and pasta were the main contributing foodstuffs to the global exposure to DON, even among infants; thus, those foods should be considered a priority for food control or to develop strategies to reduce the exposure. In any case, further toxicological and epidemiological studies are required in order to refine the safety thresholds accounting for the sensitivity of the infant population. 相似文献
76.
David Ramos Jos Cidrs Borja Plaza Carolina Moravec Antonia de la Torre Malte Richard Karl Frvel David Poyatos 《Materials》2022,15(15)
The tendency over the last decades in the aerospace industry is to substitute classic metallic materials with new composite materials such as carbon fiber composites (CFC), fiber glass, etc., as well as adding electronic devices to ensure the safety and proper platform operation. Due to this, to protect the aircraft against the Electromagnetic Environmental Effects (E3), it is mandatory to develop accurate electromagnetic (EM) characterization measurement systems to analyze the behavior of new materials and electronic components. In this article, several measurement methods are described to assess the EM behavior of the samples under test: microstrip transmission line for a surface current analysis, free space to obtain intrinsic features of the materials and shielding effectiveness (SE) approaches to figure out how well they isolate from EM fields. The results presented in this work show how the different facilities from the National Institute of Aerospace Technology (INTA) are suitable for such purposes, being capable of measuring a wide variety of materials, depending on the type of test to be carried out. 相似文献
77.
Childhood sequelae of infant lung disease: exercise and pulmonary function abnormalities after bronchopulmonary dysplasia 总被引:5,自引:0,他引:5
D Bader A D Ramos C D Lew A C Platzker M W Stabile T G Keens 《The Journal of pediatrics》1987,110(5):693-699
To determine the long-term pulmonary sequelae and effect on exercise tolerance of bronchopulmonary dysplasia (BPD), we studied 10 children at a mean age of 10.4 years, who had been born prematurely, survived respiratory distress syndrome, and subsequently developed BPD, and compared them with eight age-matched normal children born at term. Pulmonary function tests and graded exercise stress tests were performed. Residual volume, the ratio between residual volume and total lung capacity, vital capacity, forced expiratory volume in 1 second, forced expiratory flow between 25% and 75% of vital capacity, and maximal expiratory flows at 80%, 70%, and 60% of total lung capacity were all abnormal (P less than 0.02) in the children with BPD, compared with control values. Pre-exercise transcutaneous CO2 tension was higher (P less than 0.05) in the BPD group than in the control group. At maximal workload, tcPCO2 remained high in patients with BPD compared with control values (P less than 0.05). Arterial oxygen saturation at maximal workload fell below pre-exercise levels in the BPD group (P less than 0.05) but not in control children. There were no differences in maximal oxygen consumption between the BPD group and control children. Exercise-induced bronchospasm occurred in 50% of the BPD group, but not in the control group. We conclude that long-term survivors of BPD have evidence of airway obstruction, hyperinflation, and airway hyperreactivity, compared with a control group. Aerobic fitness was not significantly different in the BPD and control groups, but was achieved in the BPD group at the expense of a fall in SaO2 and a rise in tcPCO2. 相似文献
78.
79.
80.
Background Hereditary pancreatitis is an important cause of chronic pancreatitis, which may result in endocrine and exocrine failure.
This may necessitate simultaneous pancreas and kidney transplant (SPK). Bladder drainage of the exocrine secretions may cause
problems.
Aim To report one such case and its surgical correction.
Methods A 20-year-old male with insulin-dependent diabetes mellitus secondary to idiopathic chronic pancreatitis had a SPK with bladder
drainage. Urological and metabolic complications secondary to the drainage of pancreatic secretions, rich in proteolytic enzymes
required convertion from bladder to enteric drainage.
Results He was able to discontinue his pancreatic enzyme supplements, ceased to have steatorrhoea and gained weight. He was referred
to the €pean Registry of Hereditary Pancreatitis and Familial Pancreatic Cancer (€PAC), hereditary pancreatitis was confirmed
by genetic analysis.
Conclusion Enteric-drained pancreas transplantation is a successful treatment for exocrine as well as endocrine pancreatic failure and
should be considered as a treatment option in patients with chronic pancreatitis. 相似文献