全文获取类型
收费全文 | 4462篇 |
免费 | 265篇 |
国内免费 | 87篇 |
专业分类
耳鼻咽喉 | 56篇 |
儿科学 | 247篇 |
妇产科学 | 67篇 |
基础医学 | 525篇 |
口腔科学 | 113篇 |
临床医学 | 346篇 |
内科学 | 1041篇 |
皮肤病学 | 129篇 |
神经病学 | 273篇 |
特种医学 | 445篇 |
外科学 | 572篇 |
综合类 | 39篇 |
一般理论 | 1篇 |
预防医学 | 432篇 |
眼科学 | 53篇 |
药学 | 240篇 |
中国医学 | 38篇 |
肿瘤学 | 197篇 |
出版年
2023年 | 23篇 |
2022年 | 42篇 |
2021年 | 97篇 |
2020年 | 63篇 |
2019年 | 106篇 |
2018年 | 133篇 |
2017年 | 89篇 |
2016年 | 75篇 |
2015年 | 95篇 |
2014年 | 128篇 |
2013年 | 163篇 |
2012年 | 243篇 |
2011年 | 237篇 |
2010年 | 161篇 |
2009年 | 162篇 |
2008年 | 197篇 |
2007年 | 217篇 |
2006年 | 207篇 |
2005年 | 175篇 |
2004年 | 174篇 |
2003年 | 178篇 |
2002年 | 169篇 |
2001年 | 155篇 |
2000年 | 157篇 |
1999年 | 132篇 |
1998年 | 108篇 |
1997年 | 104篇 |
1996年 | 84篇 |
1995年 | 70篇 |
1994年 | 57篇 |
1993年 | 61篇 |
1992年 | 62篇 |
1991年 | 51篇 |
1990年 | 67篇 |
1989年 | 67篇 |
1988年 | 70篇 |
1987年 | 59篇 |
1986年 | 48篇 |
1985年 | 45篇 |
1984年 | 34篇 |
1983年 | 23篇 |
1982年 | 22篇 |
1981年 | 13篇 |
1980年 | 18篇 |
1979年 | 24篇 |
1978年 | 12篇 |
1977年 | 25篇 |
1976年 | 24篇 |
1975年 | 21篇 |
1972年 | 10篇 |
排序方式: 共有4814条查询结果,搜索用时 31 毫秒
111.
112.
Stijn JB Van Weyenberg Sietze T Van Turenhout Maarten AJM Jacobs Gerd Bouma Chris JJ Mulder 《Digestive endoscopy》2012,24(4):247-254
Background and Aim: Little is known about the causes of overt obscure gastrointestinal bleeding (OGIB) in patients using anti‐thrombotic therapy. We aimed to describe video capsule endoscopy (VCE) findings and to identify factors associated with positive findings in these patients. Methods: We carried out a retrospective study of 56 patients who underwent VCE for evaluation of previous overt OGIB during anti‐thrombotic therapy. VCE studies were re‐evaluated by a gastroenterologist blinded to clinical details. Clinical data included in the multivariate analysis were sex, age, indication for and type of anti‐thrombotic therapy, hemodynamic instability on admission, type of blood loss, hemoglobin on admission, use of a proton pump inhibitor, NSAID use, time between bleeding episodes and VCE, and whether or not anti‐thrombotic therapy was resumed before the VCE study. Results: A probable cause for gastrointestinal bleeding was identified in 28 (50%) of the 56 studies. Angiodysplasia was found in 19 patients. Twenty‐two studies showed a possible cause in the small bowel. Multivariate logistic regression analysis showed that reinstitution of anti‐thrombotic therapy before VCE was carried out was the only independent predictor of positive VCE findings (OR: 8.61, 95% CI: 1.20–60.42, P = 0.032). Conclusions: Small intestinal angiodysplasia was the most common cause for overt OGIB. Reinstitution of withdrawn anti‐thrombotic drugs before the VCE examination was carried out was associated with positive VCE findings in multivariate analysis. 相似文献
113.
114.
The involvement of the renin-angiotensin system gene polymorphisms in coronary heart disease 总被引:1,自引:0,他引:1
Hernández Ortega E Medina Fernández-Aceituno A Rodríguez Esparragón FJ Hernández Perera O Melián Nuez F Delgado Espinosa A Fíuza Pérez D Anabitarte Prieto A Rodríguez Pérez JC 《Revista espa?ola de cardiología》2002,55(2):92-99
INTRODUCTION AND OBJECTIVES: Previous studies angiotensin-converting enzyme gene insertion/deletion polymorphism ACE (I/D), angiotensinogen gene polymorphism, and angiotensin II AT1 receptor polymorphism in relation to coronary heart disease controversial results. This study was designed to analyze the association between these gene polymorphisms and the first coronary event in individuals residing on Grand Canary Island, Spain. PATIENTS AND METHOD: Case-control study. Case subjects (n = 304) were recruited at the first coronary event; age-matched controls (n = 315) were randomly selected from the Grand Canary population. Participants were examined for the usual risk factors. Blood samples were obtained for biochemical analyses and DNA extraction. Genotyping was performed by PCR and restriction analysis. RESULTS: Neither ACE (I/D) nor AT1 receptor polymorphism was associated with coronary heart disease, whereas the frequency distribution of AGT M235T genotypes among patients and control subjects (TT: 29% and 19%; MT: 48% and 50%; MM: 22% and 31%, respectively) was statistically different (p = 0.003). Multiple logistic regression analysis identified the TT genotype of the angiotensinogen gene (OR = 1.9; 95% CI 1.1-3.4), diabetes (OR = 4.4; 95% CI 2.0-9.4) and hypertension (OR = 2.1; 95% CI 1.3-3.3) as risk factors predicting the coronary event. CONCLUSIONS: Our results provide no evidence of an association between ACE (I/D) or AT1 receptor polymorphism and coronary heart disease. However, homozygosity for the T allele of the angiotensinogen gene, diabetes and hypertension independently place individuals at higher risk of experiencing a coronary event on Grand Canary Island. 相似文献
115.
Santamaría R Espinosa M Ortega R López Rubio F Sánchez J Torres A Aljama P 《Nefrología : publicación oficial de la Sociedad Espa?ola Nefrologia》2004,24(Z3):56-60
Hemoglobin and myoglobin heme pigments and iron have acute and chronic nephrotoxic effects, which are often associated with massive hemolysis and rhabdomyolysis. We report a patient with a myelodysplastic syndrome and paroxysmal nocturnal hemoglobinuria phenotype who developed an acute renal failure after a severe haemolytic crisis. There was not evidence of renal vascular pathology, urinary tract obstruction or prerenal factors. Renal biopsy showed features of acute tubular necrosis, with extended iron deposits in tubule cell cytoplasm and tubulo-interstitial fibrosis and atrophy. The patient was oliguric requiring hemodialisys during three weeks, recovering renal function on the fourth week after admission. This case underlines the nephrotoxic role of heme pigment and iron, and possible pathophysiologic mechanisms involved in acute and chronic toxicity of both agents are reviewed. 相似文献
116.
Restriction of cell lysis by homologous complement: II. Protection of erythrocytes against lysis by newly activated complement 总被引:1,自引:0,他引:1
Our previous work revealed that homologous complement (C) was ineffective in lysing antibody-sensitized erythrocytes (EA) even at high concentrations. It was also shown that activation of complement on homologous EA resulted in the binding of C9 and the formation of EA bearing complement proteins C1 through C9 (EAC1-9), yet few hemolytic sites were formed. Instead, as shown here, the formation of homologous EAC1-9 caused the cells to become resistant to lysis even by heterologous complement during a second incubation. In contrast, when homologous EAC1-8 were produced by incubating EA with C9-depleted serum, such intermediates were not protected against lysis by heterologous complement during a second incubation. Furthermore, homologous C9 on EAC1-9 was able to reduce the hemolytic efficiency of heterologous complement without blocking C activation and the formation of new C5b-9 complexes. Protection was not modified when homologous EAC1-9 were produced in one step, by incubation of EA with serum, or sequentially by adding C9 to EAC1-8. The minimum number of 9-sites required to confer a protective effect on EAC1-9 was less than 200 per cell. Thus, in addition to its known effect in heterologous cell killing, homologous C9 is capable of protecting homologous cells against inadvertent complement lysis. 相似文献
117.
Callén E Casado JA Tischkowitz MD Bueren JA Creus A Marcos R Dasí A Estella JM Muñoz A Ortega JJ de Winter J Joenje H Schindler D Hanenberg H Hodgson SV Mathew CG Surrallés J 《Blood》2005,105(5):1946-1949
Fanconi anemia (FA) is a genetic disease characterized by bone marrow failure and cancer predisposition. Here we have identified Spanish Gypsies as the ethnic group with the world's highest prevalence of FA (carrier frequency of 1/64-1/70). DNA sequencing of the FANCA gene in 8 unrelated Spanish Gypsy FA families after retroviral subtyping revealed a homozygous FANCA mutation (295C>T) leading to FANCA truncation and FA pathway disruption. This mutation appeared specific for Spanish Gypsies as it is not found in other Gypsy patients with FA from Hungary, Germany, Slovakia, and Ireland. Haplotype analysis showed that Spanish Gypsy patients all share the same haplotype. Our data thus suggest that the high incidence of FA among Spanish Gypsies is due to an ancestral founder mutation in FANCA that originated in Spain less than 600 years ago. The high carrier frequency makes the Spanish Gypsies a population model to study FA heterozygote mutations in cancer. 相似文献
118.
Maria Angeles Ortega Maria Isabel Torres Maria Isabel Fernandez Antonio Rios Antonio Sanchez-Pozo Angel Gil 《Digestive diseases and sciences》1997,42(8):1715-1723
We have assessed the effect of the oral ingestion of thioacetamide on small intestine structure and function. Thioacetamide-treated rats showed diminished mucosa weight; protein, DNA, and RNA content; and leucine aminopeptidase activity as compared to controls in both jejunum and ileum. In the jejunum, there was a reduction in the activities of alkaline phosphatase, ATPase, glucose-6-phosphatase, and myeloperoxidase, whereas in the ileum, maltase, lactase, and -glutamyltranspeptidase were reduced. In both jejunum and ileum we found enlarged intercellular spaces, dark epithelial enterocytes, and lymphocyte infiltration. Enterocytes showed lobulated nuclei, deranged mitochondria with loss of their cristae, dilated rough endoplasmic reticulum containing dense material, and vesiculation of the smooth endoplasmic reticulum and the Golgi apparatus. Smooth muscle cells of the intestine exhibited ultrastructural alterations. These findings indicate that chronic oral intake of thioacetamide mimics not only hepatic alterations but also small intestine alterations normally associated with human cirrhosis. 相似文献
119.
Toral Marín J Ortega F Cejudo P Elías T Sánchez H Montemayor T 《Archivos de bronconeumología》1999,35(3):117-121
The aim of this study was to assess peripheral muscle strength in patients with chronic obstructive pulmonary disease (COPD) using a simple test and to look for correlation with function variables, physiological strength variables and quality of life parameters. Twenty-three COPD patients with moderate to severe air-flow limitation (FEV1 = 39 +/- 12%) in stable phase but displaying inability to carry out daily tasks were enrolled. Peripheral muscle strength was assessed in all patients by measuring the maximum load in a single repetition of five simple upper and lower extremity exercises performed at a multi-gymnastics station. Results were compared to respiratory function variables (FVC, FEV1, FEV1/FVC and gasometry), to results of an exercise test on a cycle ergometer with monitoring of respiratory gases (VEmax, VO2max and Wmax), to endurance (minutes) to dyspnea (Mahler's scale) and to quality of life (Chronic Respiratory Disease Questionnaire-CRDQ). No relation between functional parameters and endurance in minutes was found. Minute ventilation (VE) proved to be significantly related to oxygen intake (VO) and maximum work in the stress test. Dyspnea on Mahler's scale was unrelated, but fatigue variables and emotional function variables on the CRDQ were related. We conclude that peripheral muscle strength is unrelated to level of flow limitation or exercise tolerance in COPD patients. Peripheral muscle strength is related, however, to maximum work load and some aspects of quality of life. 相似文献
120.
Mario Juarez‐Ortega Víctor G. Hernandez Patricia Arce‐Paredes Enrique B. Villanueva Miguel Aguilar‐Santelises Oscar Rojas‐Espinosa 《International journal of experimental pathology》2015,96(1):31-41
Leprosy is a disease consisting of a spectrum of clinical, bacteriological, histopathological and immunological manifestations. Tuberculoid leprosy is frequently recognized as the benign polar form of the disease, while lepromatous leprosy is regarded as the malignant form. The different forms of leprosy depend on the genetic and immunological characteristics of the patient and on the characteristics of the leprosy bacillus. The malignant manifestations of lepromatous leprosy result from the mycobacterial‐specific anergy that develops in this form of the disease. Using murine leprosy as a model of anergy in this study, we first induced the development of anergy to Mycobacterium lepraemurium (MLM) in mice and then attempted to reverse it by the administration of dialysable leucocyte extracts (DLE) prepared from healthy (HLT), BCG‐inoculated and MLM‐inoculated mice. Mice inoculated with either MLM or BCG developed a robust cell‐mediated immune response (CMI) that was temporary in the MLM‐inoculated group and long‐lasting in the BCG‐inoculated group. DLE were prepared from the spleens of MLM‐ and BCG‐inoculated mice at the peak of CMI. Independent MLM intradermally‐inoculated groups were treated every other day with HLT‐DLE, BCG‐DLE or MLM‐DLE, and the effect was documented for 98 days. DLE administered at a dose of 1.0 U (1 × 106 splenocytes) did not affect the evolution of leprosy, while DLE given at a dose of 0.1 U showed beneficial effects regardless of the DLE source. The dose but not the specificity of DLE was the determining factor for reversing anergy. 相似文献