全文获取类型
收费全文 | 92124篇 |
免费 | 8966篇 |
国内免费 | 171篇 |
专业分类
耳鼻咽喉 | 1317篇 |
儿科学 | 2819篇 |
妇产科学 | 2034篇 |
基础医学 | 13000篇 |
口腔科学 | 2144篇 |
临床医学 | 11358篇 |
内科学 | 16157篇 |
皮肤病学 | 1519篇 |
神经病学 | 7973篇 |
特种医学 | 2937篇 |
外国民族医学 | 10篇 |
外科学 | 12396篇 |
综合类 | 1709篇 |
一般理论 | 81篇 |
预防医学 | 10871篇 |
眼科学 | 1953篇 |
药学 | 7246篇 |
2篇 | |
中国医学 | 82篇 |
肿瘤学 | 5653篇 |
出版年
2022年 | 852篇 |
2021年 | 1722篇 |
2020年 | 1137篇 |
2019年 | 1696篇 |
2018年 | 2028篇 |
2017年 | 1408篇 |
2016年 | 1522篇 |
2015年 | 1644篇 |
2014年 | 2144篇 |
2013年 | 3241篇 |
2012年 | 4350篇 |
2011年 | 4568篇 |
2010年 | 2405篇 |
2009年 | 2229篇 |
2008年 | 3690篇 |
2007年 | 3949篇 |
2006年 | 3815篇 |
2005年 | 3808篇 |
2004年 | 3499篇 |
2003年 | 3236篇 |
2002年 | 3169篇 |
2001年 | 2738篇 |
2000年 | 2837篇 |
1999年 | 2527篇 |
1998年 | 1094篇 |
1997年 | 894篇 |
1996年 | 887篇 |
1995年 | 792篇 |
1994年 | 817篇 |
1993年 | 752篇 |
1992年 | 2102篇 |
1991年 | 2027篇 |
1990年 | 1902篇 |
1989年 | 1862篇 |
1988年 | 1767篇 |
1987年 | 1777篇 |
1986年 | 1684篇 |
1985年 | 1666篇 |
1984年 | 1387篇 |
1983年 | 1259篇 |
1982年 | 843篇 |
1981年 | 717篇 |
1979年 | 1219篇 |
1978年 | 873篇 |
1977年 | 762篇 |
1976年 | 718篇 |
1975年 | 716篇 |
1974年 | 860篇 |
1973年 | 753篇 |
1972年 | 735篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
An alloantiserum, termed R2, specifically agglutinates red blood cells (RBC) from line 100B chickens that are susceptible to avian leukosis viruses (ALV) belonging to subgroups B and E, but does not agglutinate RBC from congenic inbred line 7(2 )chickens that are resistant to ALV B and E. The R2 antigen was also detected on lymphocytes and thrombocytes. Using chickens from a special cross, it was found that R2 reactivity requires that the chickens must: (1) be susceptible to infection by ALV-E; and (2) express a viral envelope gene with subgroup E specificity. With R2 antiserum, a nearly perfect association was observed between agglutination and susceptibility to ALV-B in F(2) chickens containing endogenous viral genes ev2 and/or ev3. These results support earlier evidence that ALV-B and ALV-E share receptors. Moreover, the R2 antiserum was shown to neutralize ALV-E. The R2 antigen showed Mendelian segregation in chickens of a commercial White Leghorn strain-cross containing ev3, ev6 and ev9. However, commercial chickens with or without the R2 antigen did not differ in susceptibility to lymphoid leukosis induction or immune response on infection with ALV of subgroup A for complex reasons we discuss. 相似文献
82.
83.
Four groups of piglets were used to test the use of pericardium and periosteum as free grafts in the repair of full thickness cervical tracheal defects. Pericardium provided an airtight, rapidly healing graft, but did not give sufficient structural rigidity to prevent narrowing and growth failure at the graft site. Composite grafts of pericardium and periosteum were also unsatisfactory, in that the periosteum failed to produce enough bone to prevent collapse of the graft. Since previous studies have shown that periosteal grafts result in good bone formation when applied alone or as an extramucosal support, it is concluded that the osteogenic potential is dependent on the available blood supply and speed of revascularization. It appears that the presence of pericardium in the composite grafts may have inhibited this property. 相似文献
84.
V Raptopoulos A Davidoff A Karellas M A Davis B L Coolbaugh E H Smith 《AJR. American journal of roentgenology》1988,150(6):1303-1306
Visualization of the head of the pancreas by CT was prospectively evaluated in two groups of 100 patients who did not have pancreatic disease. Patients were given either a fat-density oral contrast material (12.5% corn-oil emulsion and metoclopramide) or a conventional high-density oral contrast material (barium suspension or iodinated solution). There was no statistically significant difference in the subjects' tolerance to the two regimens. There was, however, a significant improvement in ability to distinguish the head of the pancreas from the duodenal C-loop when the fat-density contrast material was given. When pancreaticoduodenal discrimination was graded, patients given corn-oil emulsion and metoclopramide received an average score of 0.94, whereas those given the high-density agent received an average score of 0.74, with 1.00 being the highest possible score (p less than .005). These data suggest that for routine CT evaluation of the head of the pancreas, a combination of corn-oil emulsion and metoclopramide may be superior to the conventional high-density oral contrast agents given without metoclopramide. 相似文献
85.
The high incidence of trauma among young men has been observed in many countries. To better understand this risk, we analyzed male injuries and their causes in Finland. The incidence peak of medically attended trauma in men aged 15-24 years was caused by occupational and sports injuries, whereas that of hospitalizations was due to motor vehicle injuries. Age patterns of nonfatal trauma resembled those recorded in the U.S.A. However, patterns and causes of fatal trauma were very different in the two countries: early adulthood in the U.S.A. and late middle-age in Finland were the ages of highest injury mortality. The majority of deaths in young men were caused by motor vehicle injuries in the U.S.A., whereas suicides and the extremely high rate of fatal non-motor vehicle accidents, largely due to alcohol poisoning and drownings, formed the main bulk of injury mortality in Finland. Similarities in early adulthood suggest general biological factors, whereas the deviance of the middle-aged male Finns from the general pattern may indicate more specific psychosocial factors. 相似文献
86.
The portrayal of alcohol was examined in a systematic sampleof 50 programmes broadcast on British television. Four out offive programmes contained visual or verbal references to alcohol.On average, there was a reference to alcohol in every 6 minutesof programming. The programmes showed more alcohol being consumedthan soft drinks or beverages, but there were few referencesto the hazards of alcohol consumption. The main recommendationis that television companies should accept a responsibilityfor presenting a more realistic and healthier approach to theuse of alcohol in Britain 相似文献
87.
J Q Koenig D S Covert M S Smith G van Belle W E Pierson 《Toxicology and industrial health》1988,4(4):521-532
Separate exposures to 0.12 ppm ozone (O3) or 0.18 ppm nitrogen dioxide (NO2) have not demonstrated consistent changes in pulmonary function in adolescent subjects. However, in polluted urban air, O3 and NO2 occur in combination. Therefore, this project was designed to investigate the pulmonary effects of combined O3 and NO2 exposures during intermittent exercise in adolescent subjects. Twelve healthy and twelve well-characterized asthmatic adolescent subjects were exposed randomly to clean air or 0.12 ppm O3 and 0.30 ppm NO2 alone or in combination during 60 minutes of intermittent moderate exercise (32.5 1/min). The inhalation exposures were carried out while the subjects breathed on a rubber mouthpiece with nose clips in place. The following pulmonary functional values were measured before and after exposure: peak flow, total respiratory resistance, maximal flow at 50 and 75 percent of expired vital capacity, forced expiratory volume in one second and forced vital capacity (FVC). Statistical significance of pulmonary function changes was tested by analysis of covariance for repeated measures. After exposure to 0.12 ppm O3 a significant decrease was seen in maximal flow at 50% of FVC in asthmatic subjects. After exposure to 0.30 ppm NO2 a significant decrease was seen in FVC also in the asthmatic subjects. One possible explanation for these changes is the multiple comparison effect. No significant changes in any parameters were seen in the asthmatic subjects after the combined O3-NO2 exposure or in the healthy subjects after any of the exposures. 相似文献
88.
B A Derfus M E Csuka G F Carrera G A Hanson R E Smith 《The Journal of rheumatology》1991,18(5):738-742
We describe a patient with viral induced aplastic anemia who developed severe bone pain after treatment with multiple courses of antithymocyte globulin, cyclosporine A, recombinant human granulocyte macrophage colony stimulating factor and deferoxamine. Radiographs and bone biopsy revealed extensive new trabecular bone formation in long bone diaphyses and adjacent periosteal reaction. The effects of hematopoietic growth factors, cyclosporine A and deferoxamine on bone metabolism are reviewed. 相似文献
89.
P C Martin J L Smith D R Pulitzer R J Reed 《The American journal of surgical pathology》1992,16(4):417-425
A distinctive systematized epithelial nevus and associated multifocal carcinomas of the microcystic and sclerosing sweat duct type affected the lower extremities of a 9-year-old girl. The carcinomas were well differentiated and were both adenosyringomatous and microcystic. They qualify as microcystic and compound. In both the epithelial nevi and the carcinoma, primordial potentials are recapitulated. 相似文献
90.
Alex Y. Chang Z. Nora Tu Julia L. Smith Philip Bonomi Thomas J. Smith Peter H. Wiernik Ronald Blum 《Investigational new drugs》1995,13(2):137-141
Summary Fifty-five patients with metastatic non-small cell lung cancer (NSCLC) were entered into this phase II randomized study for evaluating three new agents: gallium nitrate, amonafide and teniposide. The patients had to have ECOG performance status 0 or 1, no prior chemotherapy, and adequate hematological, hepatic and renal functions. Forty-seven patients were eligible and evaluable. Fourteen were randomized to receive gallium nitrate, 18 to amonafide and 15 to teniposide. Seventy-four percent of eligible patients were male. The majority of patients (89%) had an ECOG performance status 1. ECOG grade 4 toxicity occurred twice in patients on gallium nitrate, seven times on amonafide and 18 times on teniposide. The cause of death was attributed to amonafide in one patient (from sepsis) and to teniposide in two patients (due to infection and leukopenia). There was no objective response in all the patients entered. The overall survival times ranged from 2 weeks to 156 weeks with a median of 23 weeks. There were no survival differences among the three treatment arms. We conclude that gallium nitrate, amonafide and teniposide are inactive in metastatic NSCLC and do not warrant any further testing in this disease.The contents of this study is solely the responsibility of the authors and does not necessarily represent the official views of the National Cancer Institute. 相似文献