全文获取类型
收费全文 | 705764篇 |
免费 | 48871篇 |
国内免费 | 1304篇 |
专业分类
耳鼻咽喉 | 9166篇 |
儿科学 | 23269篇 |
妇产科学 | 17603篇 |
基础医学 | 110391篇 |
口腔科学 | 19955篇 |
临床医学 | 63748篇 |
内科学 | 134292篇 |
皮肤病学 | 16159篇 |
神经病学 | 49430篇 |
特种医学 | 25738篇 |
外国民族医学 | 76篇 |
外科学 | 104462篇 |
综合类 | 14818篇 |
现状与发展 | 2篇 |
一般理论 | 160篇 |
预防医学 | 51385篇 |
眼科学 | 16318篇 |
药学 | 53942篇 |
3篇 | |
中国医学 | 2359篇 |
肿瘤学 | 42663篇 |
出版年
2019年 | 5430篇 |
2018年 | 7857篇 |
2017年 | 6105篇 |
2016年 | 6819篇 |
2015年 | 7550篇 |
2014年 | 10261篇 |
2013年 | 15377篇 |
2012年 | 20488篇 |
2011年 | 21482篇 |
2010年 | 12715篇 |
2009年 | 11930篇 |
2008年 | 19986篇 |
2007年 | 21504篇 |
2006年 | 21896篇 |
2005年 | 20433篇 |
2004年 | 19984篇 |
2003年 | 18938篇 |
2002年 | 18448篇 |
2001年 | 36325篇 |
2000年 | 36894篇 |
1999年 | 30377篇 |
1998年 | 7875篇 |
1997年 | 6662篇 |
1996年 | 6970篇 |
1995年 | 6627篇 |
1994年 | 6097篇 |
1993年 | 5589篇 |
1992年 | 22967篇 |
1991年 | 22924篇 |
1990年 | 22309篇 |
1989年 | 22076篇 |
1988年 | 20035篇 |
1987年 | 19417篇 |
1986年 | 18467篇 |
1985年 | 17305篇 |
1984年 | 12698篇 |
1983年 | 10741篇 |
1982年 | 5921篇 |
1979年 | 11518篇 |
1978年 | 8128篇 |
1977年 | 6832篇 |
1976年 | 6594篇 |
1975年 | 7268篇 |
1974年 | 8498篇 |
1973年 | 8141篇 |
1972年 | 7658篇 |
1971年 | 7127篇 |
1970年 | 6877篇 |
1969年 | 6306篇 |
1968年 | 5780篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
181.
Intraventricular hemorrhage (IVH) in preterm infants is well known to be associated with the high morbidity and mortality of this group. Previous studies have suggested altered cerebral blood flow (CBF) as an important pathologic factor. We measured the CBF in nearterm rabbit fetuses using the hydrogen clearance technique. The local CBF of the rabbit fetuses was significantly low compared with that of the maternal rabbits. The response of CBF to changes in PaCO2 was observed in rabbit fetuses. The CO2 reactivity index of the fetal rabbit was lower than that of the maternal rabbit. This low CO2 reactivity might reflect the immaturity of the fetal brain and its low CBF. We were unable to monitor the fetal blood pressure, but the fetal CBF remained stable when the maternal blood pressure was altered. It is well known that IVH in preterm infants originates from the subependymal germinal matrix and that this has many fragile vessels. Our observation suggests that even a small increase of CBF during hypercapnia might have a large effect towards producing hemorrhage. 相似文献
182.
M. D. Taylor M. L. de Ceballos S. Rose P. N. Chong P. Jenner C. D. Marsden 《Journal of neural transmission (Vienna, Austria : 1996)》1991,3(2):99-108
Summary Aged common marmosets were treated with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP; 0.5–2.0 mg/kg/week i.p.) for 16 or 24 weeks, observed for a total of 30 weeks and then killed for measurement of biochemical pramaters in basal ganglia. The MPTP treatment induced a marked depletion in dopamine, 3,4-dihydroxyphenylacetic acid and homovanillic acid levels in the caudate nucleus and putamen. In contrast, the concentrations of five neuropeptides: [Met5]-enkephalin, [Leu5]-enkephalin, cholecystokinin, substance P and neurotensin as measured by a combined HPLC/RIA method, remained unaltered in all basal ganglia regions examined. Enkephalin precursor levels, as reflected by cryptic [Met5]-enkephalin content, were increased in the putamen, but not in the caudate nucleus, as a consequence of MPTP administration. Cryptic [Leu5]-enkephalin content remained unchanged in the striatum of MPTP treated marmosets. Overall, these results suggest an increase in striatal [Met5]-enkephalin release following chronic MPTP treatment of aged marmosets. However, the chronic treatment of aged marmosets with MPTP does not reproduce the neuropeptide alterations characteristic of Parkinson's disease. 相似文献
183.
N U Khodzhaeva I V Ovchinnikov A G Bogdanov-Berezovski? Sh A Khuda?bergenov 《Laboratornoe delo》1991,(3):60-61
The duodenal contents were examined in 81 patients with gastroduodenal ulcer. Bile acid concentrations, alkaline phosphatase activity, and sodium ion concentration were measured for the detection of duodenogastric reflux. Measurements of sodium ion concentration permitted estimation of the immediate volume of the duodenogastric reflux in the gastric contents. No methods for duodenogastric reflux detection should be given preference in examinations of peptic ulcer patients. Multiple-modality studies appear to be the most effective. 相似文献
184.
Computer competition analysis of 3H-DHA (3H-dihydroalprenolol, a nonselective beta-adrenergic radioligand) binding in the presence of unlabeled metoprolol (a beta 1-selective antagonist) indicates the existence of both beta 1- and beta 2-adrenergic receptor subtypes in the rat placenta and confirms previous reports that both beta-adrenoceptors are present in adult rat cortex. In the fetal brain (20th day of gestation), however, only beta 1-receptors were detected. Pregnant rats were chronically exposed to methadone from day 7 to day 20 of gestation via implanted osmotic minipumps (6.3-9.0 mg/kg/day). This treatment schedule did not induce a change in the affinity and density of either beta-receptor subtype in the placental, fetal and maternal brain homogenates. The results are discussed in terms of the reported monoaminergic and opiate receptor functional interactions. 相似文献
185.
186.
A patient with Hodgkin’s disease received a fractionated 3, 740 rad dosage over 4 weeks to a portal that included both kidneys. Three months later a computed tomographic scan obtained 2 hours after intravenous contrast injection demonstrated sharply demarcated, dense, persistent nephrograms corresponding to the irradiated areas. These changes are ascribed to acute radiation nephritis, reflecting tubular stasis and ischemia. 相似文献
187.
188.
Prognostic factors in the treatment of hepatocellular carcinoma with transcatheter arterial embolization and arterial infusion. 总被引:8,自引:0,他引:8
Y Yamashita M Takahashi Y Koga R Saito S Nanakawa Y Hatanaka N Sato K Nakashima J Urata K Yoshizumi 《Cancer》1991,67(2):385-391
From January 1986 to December 1988, a prospective trial of transcatheter arterial treatment was carried out for hepatocellular carcinoma (HCC). Two hundred seventy-five patients were included. Okuda's staging system was employed. Patients with Stage I and II HCC were treated by transcatheter arterial embolization (TAE) with a gelatin sponge containing an anti-cancer agent (protocol 1a); a gelatin sponge and iodized oil mixed with an anti-cancer agent (protocol 1b); or iodized oil mixed with an anti-cancer agent (protocol 2). Patients with Stage III HCC were treated with iodized oil with anti-cancer agent (protocol 2). As an exception, patients with an unsuccessful superselective catheterization into the proper hepatic artery by Seldinger technique or obstruction of the main trunk of the portal vein were treated with percutaneous transcatheter arterial infusion into the common hepatic artery regardless of stage (protocol 3). Tumor type and extension, area of tumor involvement, portal vein involvement, method of treatment, and presence of ascites and icterus were found to be the significant factors for an initial response to therapy. Treatment method was the most important factor. Respective survival rates at 1 and 2 years were 70.9% and 55.3% for protocol 1a; 62.3% and 43.8% for protocol 1b; 37.8% and 18.3% for protocol 2; and 16.5% and 0% for protocol 3. Many factors proved to significantly influenced prognosis; however, tumor type had the most important prognostic significance followed by AFP value, ascites, treatment protocol, and area of tumor involvement. 相似文献
189.
The authors report their experience of anterolateral bilateral approach of cervical spine. They underline the advantages and inconvenience of this route and discuss the indications. 相似文献
190.