全文获取类型
收费全文 | 48161篇 |
免费 | 2810篇 |
国内免费 | 300篇 |
专业分类
耳鼻咽喉 | 705篇 |
儿科学 | 1708篇 |
妇产科学 | 1459篇 |
基础医学 | 4493篇 |
口腔科学 | 1567篇 |
临床医学 | 4134篇 |
内科学 | 10819篇 |
皮肤病学 | 834篇 |
神经病学 | 2890篇 |
特种医学 | 1817篇 |
外国民族医学 | 4篇 |
外科学 | 9439篇 |
综合类 | 1017篇 |
现状与发展 | 3篇 |
一般理论 | 28篇 |
预防医学 | 2770篇 |
眼科学 | 1780篇 |
药学 | 3270篇 |
1篇 | |
中国医学 | 287篇 |
肿瘤学 | 2246篇 |
出版年
2024年 | 49篇 |
2023年 | 505篇 |
2022年 | 1227篇 |
2021年 | 1991篇 |
2020年 | 1192篇 |
2019年 | 1535篇 |
2018年 | 1899篇 |
2017年 | 1416篇 |
2016年 | 1695篇 |
2015年 | 1849篇 |
2014年 | 2247篇 |
2013年 | 2713篇 |
2012年 | 3967篇 |
2011年 | 3819篇 |
2010年 | 2200篇 |
2009年 | 1906篇 |
2008年 | 2958篇 |
2007年 | 3163篇 |
2006年 | 2819篇 |
2005年 | 2586篇 |
2004年 | 2322篇 |
2003年 | 1884篇 |
2002年 | 1648篇 |
2001年 | 429篇 |
2000年 | 342篇 |
1999年 | 324篇 |
1998年 | 250篇 |
1997年 | 172篇 |
1996年 | 166篇 |
1995年 | 127篇 |
1994年 | 106篇 |
1993年 | 84篇 |
1992年 | 155篇 |
1991年 | 170篇 |
1990年 | 135篇 |
1989年 | 128篇 |
1988年 | 106篇 |
1987年 | 97篇 |
1986年 | 90篇 |
1985年 | 119篇 |
1984年 | 78篇 |
1983年 | 52篇 |
1982年 | 53篇 |
1981年 | 55篇 |
1980年 | 41篇 |
1979年 | 52篇 |
1978年 | 41篇 |
1975年 | 36篇 |
1974年 | 36篇 |
1973年 | 37篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
71.
BACKGROUND: Optimal feeding practice in the first year of life is crucial for the survival and health of infants, and has long-term consequences in later life. However, non-optimal feeding practices exist widely. The present study aims to explore various constraints to optimal feeding practices in the first year of life of infants in urban areas of Beijing, China. METHODS: A cross-sectional study was conducted in urban areas of Beijing from 4 July to 20 August, 1998. Two hundred and fifty-one mothers of infants aged 6-12 months were chosen from six child health centers in three different urban districts in Beijing. A self-administered structured questionnaire was used to collect data regarding feeding practices and potentially related factors. RESULTS: Feeding practice for most of the infants was in accordance with the national and international recommendations. However, the rate of incidence of exclusive breast-feeding at 3 months of age was lower than that recommended by the World Health Organisation (WHO) (55.8%), and the introduction of solid/semisolid food before 4 months of age was found in approximately 19.3% of the infants. Cow's milk was given to 21.2% of infants from 6 months of age as the sole source of milk or as a supplement. Maternal education level (OR = 2.44, 95% CI: 1.42-4.19, P < 0.05), employment (OR = 2.05, 95% CI: 1.13-3.74, P < 0.05) and antenatal nonexclusive breast-feeding plans (OR = 4.10, 95% CI: 2.24-7.50, P < 0.001) were found to be correlated to inappropriate feeding practices. CONCLUSIONS: The feeding practices for most of the urban infants was found to be in accordance with the Chinese government and WHO recommendations; however, non-optimal feeding practices presenting as the early cessation of breast-feeding and the introduction of solid/semisolid foods existed. Information regarding optimal feeding practices should be disseminated to mothers and medical professionals in China, to ensure optimal infant health. 相似文献
72.
Feza Karakayali Nihan Haberal Hale Tufan Nesrin Hasirci Ozgur Basaran Sinasi Sevmis Aydin Akdur Aysel Kiziltay Mehmet Haberal 《Journal of investigative surgery》2007,20(3):167-173
Tranilast is an antiallergic drug that interferes with proliferation and migration of vascular smooth muscle cell induced by platelet-derived growth factor (PDGF) and transforming growth factor-beta1 (TGF-beta1). We investigated the local effect of tranilast on neointimal hyperplasia using tranilast-coated prosthetic grafts. The inner sides of the thin-walled polytetrafluoroethylene (PTFE) grafts were coated with chitosan and tranilast containing chitosan solution. Wistar albino rats (32) were used in the study. Patches (1 x 2 mm) for vascular grafts were prepared. Three groups were tested: group 1 (n = 12; tranilast coated), group 2 (n = 10; adhesive-only film-layer-coated), and group 3 (n = 10; normal ePTFE patch grafts sutured to the carotid arteries of the rats). Recipient sites of the carotid arteries were excised 4 weeks after surgery. All sections were examined histologically for graft patency, thrombus formation, and neointimal thickness. Expression of PDGF, fibroblast growth factor, and TGF-beta1 on cross-sections of the neointima were evaluated by immunohistochemistry. No significant differences were found regarding mean neointimal thicknesses. PDGF and TGF-beta-1 expressions were significantly lower in group 1. Although a decrease in local effect of tranilast was observed for growth factor expressions at a drug concentration of 0.05 mg/cm(2), a significant reduction in neointimal hyperplasia was not achieved. The coating concentration of 0.05 mg/cm(2) may have been too low to produce an antiproliferative effect. Given our promising results, further studies are recommended and planned using different drug concentrations and time intervals. 相似文献
73.
François Béïque Mohamed Ali Scott MacKenzie Mark Hynes 《Journal canadien d'anesthésie》2007,54(2):158-159
74.
75.
Hasan Yüksel Ali Riza Odaba?i Selda Demircan Aslihan Karul Leyla Didem Kozaci Kutsi K?seo?lu Kadir Kizilkaya Okay Ba?ak 《Gynecological endocrinology》2006,22(7):381-387
AIM: To evaluate the effects of oral continuous 17beta-estradiol plus norethisterone acetate (E2/NETA) replacement therapy on abdominal subcutaneous fat, serum leptin level (SLL) and body composition in postmenopausal women. MATERIALS AND METHODS: A 6-month, prospective, randomized, double-blind and placebo-controlled study was conducted. Forty-three healthy naturally postmenopausal women aged 43-65 years were randomly assigned to receive E2/NETA (2 mg E2 plus 1 mg NETA, n = 22) or placebo (n = 21). Fasting SLL by enzyme-linked immunosorbent assay, subcutaneous abdominal fat thickness (STh) by ultrasound and the anthropometric indices of body weight (BW), body mass index (BMI), waist and hip circumference (WC, HC) and waist-to-hip ratio (WHR) were recorded at the beginning and the end of the study. RESULTS: After 6 months of therapy, BW and SLL increased in the placebo group (p = 0.043 and 0.033, respectively). WC, HC and STh decreased significantly in the E2/NETA group (p = 0.002, 0.006 and 0.000, respectively) and they were also significantly lower in women receiving E2/NETA than in women taking placebo (p = 0.000, 0.034 and 0.000, respectively). At baseline, SLL and STh were positively correlated with all anthropometric indices except WHR. CONCLUSION: Oral continuous combined regimen of E2/NETA significantly reduced central fat accumulation as assessed by WC and STh, and attenuated the increase in SLL. The observed changes in SLL were highly and positively related to changes in STh. The oral continuous combined E2/NETA regimen appears to have protective effects on cardiovascular function and probably on metabolic diseases by its slimming effect upon WC in postmenopausal women. 相似文献
76.
77.
78.
79.
Prevention of ethanol-induced gastric lesions in rats by natural honey, and its possible mechanism of action. 总被引:1,自引:0,他引:1
A T Ali 《Scandinavian journal of gastroenterology》1991,26(3):281-288
The effects and the mechanism of natural honey on absolute ethanol-induced gastric lesions were studied in rats. Drugs and/or honey were administered subcutaneously or orally to 48-h fasted animals at different time intervals before oral administration of ethanol (0.5 ml/100 g). Mucosal damage and pH were measured 1 h later. Honey afforded protection against gastric damage and reversed the changes in pH induced by ethanol. The effects of honey were dose- and time-dependent. Thus, pretreatment with honey (1.25 g/kg) 30 min before ethanol provided more than 80% protection. On the other hand, administration of honey simultaneously with or 5 min after ethanol failed to offer protection. The cyclooxygenase inhibitor indomethacin (IND) did not alter the protective effects when given before or after honey. The protective effects of honey could be reversed by treatment with the sulfhydryl (SH) blocker N-ethylmaleimide (NEM). Combined IND and NEM treatment caused greater reduction of the protective effects, but the values were not significantly different from those obtained with NEM alone. Thus, the gastroprotective effects of honey appeared to be mediated through SH-sensitive processes. Furthermore, the protective effects were supported by both macroscopic and microscopic findings. It is suggested that honey may be used clinically in preventing/reducing ethanol-induced gastric lesions in humans. 相似文献
80.
Perinatal hypoxia-ischaemia induces a biphasic cerebral injury: the depletion in high energy phosphates during the insult returns to normal soon after resuscitation. However, some 8–15 h later a second phase of impaired energy metabolism begins, which is related to the severity of later neurodevelopmental impairment. Delayed injury differs from acute hypoxia-ischaemia because intracellular acidosis does not occur. Apoptosis may be a mechanism of delayed cellular injury. Apoptotic cells and typical DNA fragmentation have been found after perinatal hypoxia-ischaemia. In newborn piglets, fraction of apoptotic cells was directly related to the degree of high energy phosphate depletion during hypoxia-ischaemia. Apoptosis may be interrupted: in piglets, brain cooling for 12 h following resuscitation reduced the fraction of apoptotic but not necrotic cells. These results have implications for both the understanding of cerebral injury and the use of hypothermia as a neural rescue strategy in the developing brain. 相似文献