全文获取类型
收费全文 | 7700篇 |
免费 | 749篇 |
国内免费 | 28篇 |
专业分类
耳鼻咽喉 | 88篇 |
儿科学 | 237篇 |
妇产科学 | 142篇 |
基础医学 | 1064篇 |
口腔科学 | 201篇 |
临床医学 | 829篇 |
内科学 | 1789篇 |
皮肤病学 | 159篇 |
神经病学 | 745篇 |
特种医学 | 205篇 |
外国民族医学 | 2篇 |
外科学 | 1065篇 |
综合类 | 72篇 |
一般理论 | 1篇 |
预防医学 | 704篇 |
眼科学 | 137篇 |
药学 | 434篇 |
中国医学 | 16篇 |
肿瘤学 | 587篇 |
出版年
2023年 | 48篇 |
2022年 | 87篇 |
2021年 | 234篇 |
2020年 | 102篇 |
2019年 | 268篇 |
2018年 | 302篇 |
2017年 | 217篇 |
2016年 | 204篇 |
2015年 | 227篇 |
2014年 | 264篇 |
2013年 | 377篇 |
2012年 | 447篇 |
2011年 | 470篇 |
2010年 | 280篇 |
2009年 | 228篇 |
2008年 | 353篇 |
2007年 | 390篇 |
2006年 | 389篇 |
2005年 | 332篇 |
2004年 | 277篇 |
2003年 | 274篇 |
2002年 | 282篇 |
2001年 | 173篇 |
2000年 | 200篇 |
1999年 | 177篇 |
1998年 | 73篇 |
1997年 | 72篇 |
1996年 | 59篇 |
1995年 | 56篇 |
1994年 | 50篇 |
1993年 | 41篇 |
1992年 | 143篇 |
1991年 | 157篇 |
1990年 | 128篇 |
1989年 | 131篇 |
1988年 | 119篇 |
1987年 | 100篇 |
1986年 | 111篇 |
1985年 | 74篇 |
1984年 | 67篇 |
1983年 | 54篇 |
1981年 | 27篇 |
1980年 | 25篇 |
1979年 | 50篇 |
1977年 | 28篇 |
1976年 | 29篇 |
1974年 | 23篇 |
1973年 | 35篇 |
1970年 | 23篇 |
1969年 | 24篇 |
排序方式: 共有8477条查询结果,搜索用时 15 毫秒
21.
The etiological diagnosis of obstruction is difficult during pregnancy. The authors report 3 cases of this rare association: obstruction due to adhesions [1], volvulus of the transverse colon on a common mesentery [1] and obstruction due to an appendix abscess [1]. Complementary investigations, obviously limited under these circumstances, were based on plain abdominal X-rays, repeated if necessary. The diagnosis must be made early and appropriate treatment given in order to ensure a good materno-fetal prognosis as was obtained in these 3 cases. 相似文献
22.
Regulation of Neutrophil Apoptosis by Tumor Necrosis Factor-alpha : Requirement for TNFR55 and TNFR75 for Induction of Apoptosis In Vitro 总被引:7,自引:2,他引:5
23.
The brain is isolated behind a blood-tissue barrier that restricts the access of circulating proteins to neural cells. There is evidence that some of these proteins are synthesized within the central nervous system. The present study examines the synthesis and secretion of such proteins by cultured macroglial cells. Primary glial cultures were derived from cortical and subcortical regions of neonatal rat brains, and subsequent secondary cultures were enriched in type-1 astrocytes, type-2 astrocytes, or oligodendrocytes. Newly synthesized proteins were immunoprecipitated from the culture media using antisera directed against whole rat serum. All three types of glial cells secreted a range of plasma proteins. In general, type-1 astrocytes secreted more of these proteins than did type-2 astrocytes or oligodendrocytes, although the one-dimensional polyacrylamide gel electrophoresis (PAGE) profiles were specific for each cell type. Antisera directed against specific plasma proteins identified three of the most abundant proteins secreted by type-1 astrocytes as transferrin, α-2-macroglobulin, and ceruloplasmin. Northern blot analysis of cellular RNA confirmed that type-1 astrocytes contained transferrin mRNA, and that it was more abundant in cultures derived from subcortical regions than from cortical regions. In situ hybridization studies revealed that virtually all type-1 and type-2 astrocytes contained transferrin mRNA. Since the proteins identified in this study have been proposed to have a variety of neurotrophic roles in the central nervous system, these data further extend the range of possible functions that glial cells may serve in the CNS. 相似文献
24.
25.
Walter G. Sannita Luisa Lopez Lino Maggi Guido Rosadini 《Documenta ophthalmologica. Advances in ophthalmology》1988,70(1):89-96
L-acetylcarnitine is a compound with cholinergic properties and putative action on the visual system and the glucose metabolism. Ten healthy, emmertropic volunteers (age range: 21 to 28 years) were studied. Each subject was administered 5, 10, and 30 mg/kg acute intravenous doses of L-acetylcarnitine and matching placebo. Retinal oscillatory potentials to full-field flash stimulation were recorded before and 30, 60, and 120 min after administration. A systematic reduction of the implicit time of the P2 and N2 oscillatory potential components was observed after administration of the 10 and 30 mg/kg doses: significant changes were not evident at the 5 mg dose or after placebo. The latency reduction was significantly correlated with the postdrug increment of the L-acetylcarnitine plasma concentration. No other systematic modification in latency of amplitude was observed.The results were presented in part at the XXV I.S.C.E.V. Symposium, Sarasota (Florida), April 26–30, 1987. 相似文献
26.
Steven N Singh X Charlene Tang Bramah N Singh Paul Dorian Domenic J Reda Crystal L Harris Ross D Fletcher Satish C Sharma J Edwin Atwood Alan K Jacobson H Daniel Lewis Becky Lopez Dennis W Raisch Michael D Ezekowitz 《Journal of the American College of Cardiology》2006,48(4):721-730
OBJECTIVES: The purpose of this study was to determine quality of life (QOL) and exercise performance (EP) in patients with persistent atrial fibrillation (AF) converted to sinus rhythm (SR) compared with those remaining in or reverting to AF. BACKGROUND: Restoration of SR in patients with AF improving QOL and EP remains controversial. METHODS: Patients with persistent AF were randomized double-blind to amiodarone, sotalol, or placebo. Those not achieving SR at day 28 were cardioverted and classified into SR or AF groups at 8 weeks (n = 624) and 1 year (n = 556). The QOL (SF-36), symptom checklist (SCL), specific activity scale (SAS), AF severity scale (AFSS), and EP were assessed. RESULTS: Favorable changes were seen in SR patients at 8 weeks in physical functioning (p < 0.001), physical role limitations (p = 0.03), general health (p = 0.002), and vitality (p < 0.001), and at 1 year in general health (p = 0.007) and social functioning (p = 0.02). Changes in the scores for SCL severity (p = 0.01), functional capacity (p = 0.003), and AFSS symptom burden (p < 0.001) at 8 weeks and in SCL severity (p < 0.01) and AF symptom burden (p < 0.001) at 1 year showed significant improvements in SR versus AF. Symptomatic patients were more likely to have improvement. The EP in SR versus AF was greater from baseline to 8 weeks (p = 0.01) and to 1 year (p = 0.02). The EP correlated with physical functioning and functional capacity except in the AF group at 1 year. CONCLUSIONS: In patients with persistent AF, restoration and maintenance of SR was associated with improvements in QOL measures and EP. There was a strong correlation between QOL measures and EP. 相似文献
27.
Hypertension in developing countries 总被引:2,自引:0,他引:2
A Nissinen S B?thig H Granroth A D Lopez 《Rapport trimestriel de statistiques sanitaires mondiales》1988,41(3-4):141-154
Population surveys carried out since the 1970s in 15 developing countries including 23 population groups show that the prevalence of hypertension ranges from as low as 1% in some African countries to over 30% in Brazil. A trend analysis of the mortality statistics for 35-74 year-olds from 16 countries in which data are available shows a downward trend in mortality from hypertension and cerebrovascular diseases in most of these countries. In spite of the current low prevalence in some countries, the total number of hypertensives in the developing world is high, and a cost assessment of possible antihypertensive drug treatment indicates that developing countries cannot afford the same drug treatment levels as developed countries. 相似文献
28.
Stuart Gherini Andre Lopez Lysiane Juberthie Jean Clatude Olivier 《Indian journal of otolaryngology and head and neck surgery》1994,46(2):50-62
The aim of surgical treatment of a fixed stapes is to restore an as effective as possible impedance transfer of the ossicular chain and acoustic impedance of the annular ligament of the footplate, when it has lost elasticity, and this in order to achieve the best possible physiological vibration of the inner ear fluids. 相似文献
29.
30.
The role of endogenous opiates and cholecystokinin (CCK) in the control of postprandial pyloric myoelectric activity was investigated in conscious dogs with chronically implanted intraparietal electrodes at the gastroduodenal junction. Meals consisted of either 20 g/kg of canned food (standard meal) or the same food supplemented with 0.5 mL/kg of arachis oil (fat meal). During the 6 hours after standard and fat meals, the number of pyloric spike bursts, 2-4 seconds in duration, was 61.8 +/- 15.8 and 49.9 +/- 12.7/15 minutes, respectively. Administered 15 minutes before a fat meal, naloxone (50 micrograms/kg IV) decreased the number of spike bursts by 31.4%, whereas methyl-levallorphan, a peripheral opiate antagonist, increased postprandial spike activity by 22.2% when administered IV (0.5 mg/kg) and decreased it when administered intracerobroventricularly at a dose of 10 micrograms/kg. These two antagonists administered in the same conditions before a standard meal had no effect on the postprandial spike activity. A 1-hour infusion of cholecystokinin octapeptide (CCK-8), 500 ng.kg-1.h-1 IV and 50 ng.kg-1.h-1 intracerebroventricularly, performed 1 hour after a standard meal induced a 19.6% and 15.8% decrease in the number of pyloric spike bursts, respectively. Both naloxone IV (50 micrograms/kg) and methyl-levallorphan intracerebroventricularly (10 micrograms/kg) administered before the infusion of CCK-8 reinforced this pyloric inhibition, which was antagonized by methyl-levallorphan IV (0.5 mg/kg). The CCK antagonist asperlicin, 200 micrograms/kg IV and 20 micrograms/kg intracerebroventricularly, administered before a fat meal increased pyloric spike bursts by 22.0% and 31.5%, respectively. These results indicate that after a fat meal, endogenous opiates exert a peripheral inhibitory and central stimulatory control of pyloric motility; they suggest the involvement of both peripheral and central release of CCK. 相似文献