全文获取类型
收费全文 | 315831篇 |
免费 | 18113篇 |
国内免费 | 573篇 |
专业分类
耳鼻咽喉 | 4324篇 |
儿科学 | 10851篇 |
妇产科学 | 10675篇 |
基础医学 | 48312篇 |
口腔科学 | 7771篇 |
临床医学 | 26139篇 |
内科学 | 59138篇 |
皮肤病学 | 6599篇 |
神经病学 | 22911篇 |
特种医学 | 12215篇 |
外国民族医学 | 45篇 |
外科学 | 49130篇 |
综合类 | 8096篇 |
现状与发展 | 1篇 |
一般理论 | 180篇 |
预防医学 | 21694篇 |
眼科学 | 7168篇 |
药学 | 22414篇 |
28篇 | |
中国医学 | 857篇 |
肿瘤学 | 15969篇 |
出版年
2021年 | 3160篇 |
2019年 | 3116篇 |
2018年 | 4793篇 |
2017年 | 3450篇 |
2016年 | 4087篇 |
2015年 | 4592篇 |
2014年 | 5845篇 |
2013年 | 8779篇 |
2012年 | 10702篇 |
2011年 | 10655篇 |
2010年 | 7155篇 |
2009年 | 6417篇 |
2008年 | 9568篇 |
2007年 | 10488篇 |
2006年 | 10186篇 |
2005年 | 9678篇 |
2004年 | 9281篇 |
2003年 | 8588篇 |
2002年 | 8094篇 |
2001年 | 13390篇 |
2000年 | 13765篇 |
1999年 | 11517篇 |
1998年 | 3167篇 |
1997年 | 2871篇 |
1996年 | 2685篇 |
1995年 | 2579篇 |
1994年 | 2378篇 |
1992年 | 8331篇 |
1991年 | 8472篇 |
1990年 | 8275篇 |
1989年 | 8096篇 |
1988年 | 7322篇 |
1987年 | 7082篇 |
1986年 | 6730篇 |
1985年 | 6527篇 |
1984年 | 4772篇 |
1983年 | 4128篇 |
1982年 | 2481篇 |
1979年 | 4435篇 |
1978年 | 3231篇 |
1977年 | 2736篇 |
1976年 | 2506篇 |
1975年 | 2838篇 |
1974年 | 3355篇 |
1973年 | 3364篇 |
1972年 | 3120篇 |
1971年 | 2952篇 |
1970年 | 2839篇 |
1969年 | 2582篇 |
1968年 | 2539篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
M. SILBERSTEIN O. HENNESSY L. LAU 《Journal of Medical Imaging and Radiation Oncology》1992,36(4):334-338
The radiological findings in five patients with pelvic sort tissue neo plasms directly involving the sacroiliac joint, are described. All patients had Computed Tomography (CT) examinations, two of the patients also having Magnetic Resonance Imaging (MRI). The role of imaging in this uncommon entity is discussed as well as the importance of making this diagnosis, thereby excluding unilateral sacroiliitis. The therapeutic implications of this diagnosis relate to local neural involvement, especially the sciatic nerve, and the fact that involvement of the sacroiliac joint by tumors significantly compromises chances of a successful surgical outcome. The role of MR in this condition is not yet certain, but it may prove to be the method of choice in view of its excellent depiction of skeletal neo plasms. 相似文献
992.
ELISA for quantitation of L-selectin shed from leukocytes in vivo. 总被引:13,自引:0,他引:13
O Spertini B Schleiffenbaum C White-Owen P Ruiz T F Tedder 《Journal of immunological methods》1992,156(1):115-123
L-selectin is a cell surface receptor on granulocytes, lymphocytes and monocytes that is responsible for the initial attachment of leukocytes to endothelium. The extracellular domain of L-selectin is proteolytically shed from leukocytes following cellular activation in vitro. The shed form of L-selectin (SL-selectin) is functionally active and at high concentrations can inhibit leukocyte attachment to endothelium. Therefore, an ELISA was developed to quantitate the levels of SL-selectin in biological fluids, biopsy specimens and during recombinant protein production. This simple, quantitative sandwich ELISA uses two monoclonal antibodies directed against the extracellular domain of SL-selectin. The assay has a detection range of 5-1300 ng/ml, is precise and sensitive. The ability of this assay to detect SL-selectin in serum, plasma, and culture supernatant fluid was demonstrated and it was used to quantitate circulating SL-selectin in normal and patient sera. Patients with sepsis and HIV infection showed markedly elevated SL-selectin levels in serum. Thus, the ELISA should prove useful both for laboratory purposes as well as in the diagnostic evaluation of patients with inflammatory diseases. 相似文献
993.
Summary Insulin resistance and a defective insulin activation of the enzyme glycogen synthase in skeletal muscle during euglycaemia may have important pathophysiological implications in Type 2 (non-insulin-dependent) diabetes mellitus. Hyperglycaemia may serve to compensate for these defects in Type 2 diabetes by increasing glucose disposal through a mass action effect. In the present study, rates of whole-body glucose oxidation and glucose storage were measured during fasting hyperglycaemia and isoglycaemic insulin infusion (40 mU·m–2min–1, 3 h) in 12 patients with Type 2 diabetes. Eleven control subjects were studied during euglycaemia. Biopsies were taken from the vastus lateralis muscle. Fasting and insulin-stimulated glucose oxidation, glucose storage and muscle glycogen synthase activation were all fully compensated (normalized) during hyperglycaemia in the diabetic patients. The insulin-stimulated increase in muscle glycogen content was the same in the diabetic patients and in the control subjects. Besides hyperglycaemia, the diabetic patients had elevated muscle free glucose and glucose 6-phosphate concentrations. A positive correlation was demonstrated between intracellular free glucose concentration and muscle glycogen synthase fractional velocity insulin activation (0.1 mmol/l glucose 6-phosphate: r=0.65, p<0.02 and 0.0 mmol/l glucose 6-phosphate: r= 0.91, p<0.0001). In conclusion, this study indicates an important role for hyperglycaemia and elevated muscle free glucose and glucose 6-phosphate concentrations in compensating (normalizing) intracellular glucose metabolism and skeletal muscle glycogen synthase activation in Type 2 diabetes. 相似文献
994.
995.
Y H Neggers G R Cutter J O Alvarez R L Goldenberg R Acton R C Go J M Roseman 《Early human development》1991,25(2):75-85
A retrospective follow-up study to ascertain the relationship between the level of serum zinc and its rate of change during gestation and birthweight was conducted in 476 women of lower socioeconomic status. Serum zinc concentrations measured at approximately 16 (early) and 32 weeks (later) in gestation were both found to be significant predictors of birthweight. Even after controlling for gestational age at birth and other determinants of birthweight, for each microgram/dl increase in serum zinc early and later in pregnancy, birthweight increased by 5.8 and 8.6 g, respectively. Furthermore, after adjustment for initial zinc levels both the total change (beta = -7.0, P = 0.0007) and the rate of change (beta = -60.8, P = 0.007) in serum zinc during pregnancy were inversely associated with birthweight, i.e., the larger the fall in serum zinc during pregnancy, the smaller the infant. Low serum zinc level (less than 60 micrograms/dl) late in pregnancy was associated with greater than a five-fold increase in the odds (OR = 5.8, 95% CI = 1.8, 16.4) of giving birth to a low birthweight infant. The results of this study suggest a threshold for maternal serum zinc below which the prevalence of low birthweight increases rapidly. 相似文献
996.
MICHAEL O. GAYLE C. ANTHONY RYAN SHEMIN NAZARALI 《Acta paediatrica (Oslo, Norway : 1992)》1991,80(4):486-487
ABSTRACT. A child with respiratory distress was found to have been given an antibiotic which was reconstituted with methadone. A delay in standard emergency room management led to a delay in diagnosis and treatment. 相似文献
997.
998.
999.
1000.
S. EINARSSON A. CERNE A. BENGTSSON O. STENQVIST J. P. BENGTSON 《Acta anaesthesiologica Scandinavica》1997,41(10):1285-1291
Background : The appearance of hypoxaemia immediately after anaesthesia with nitrous oxide may be partially explained by diffusion hypoxia. This study was undertaken to evaluate circulatory and respiratory variables during emergence after desflurane/nitrous oxide anaesthesia, and whether there are any differences depending on which gas is discontinued first. Methods : 20 patients were studied after gynaecological laparoscopic surgery. The depth of anaesthesia was reduced 10 min prior to the emergence by stopping the administration of one of the two inhalational agents. Desflurane was discontinued first in Group 1, nitrous oxide in Group 2. Ventilation was controlled with E'C02 maintained at 5% until the administration of the second anaesthetic gas was discontinued. Thereafter, the patients breathed spontaneously. Results : The PaC02 at which the respiratory drive reappeared after controlled normoventilation was similar in both groups, 6.1–6.5 kPa, and extubation was performed after 10–11 min. At extubarion, the end–tidal C02 and total MAC were similar in the groups, about 6.2 vol% and 0.16, respectively. Mean arterial blood pressure was significantly higher in Group 1. The cardiac output increased in both groups from about 6 1/min at the conclusion of anaesthesia to 9.0 and 7.6 1/min at 15 min in the recovery period. End–tidal O2 decreased and CO2 increased in both groups during the first 10 min in the recovery period. pH was reduced at 15 and 30 min in both groups. Conclusion : Irrespective of which agent was discontinued first, there was an increase in cardiac output, decrease in oxygenation and a modest acidosis in the first 30–min recovery period. The only significant difference between the groups was in mean arterial blood pressure in the early emergence phase with a greater MAP when N2O had been used until the conclusion of anaesthesia. 相似文献