全文获取类型
收费全文 | 426篇 |
免费 | 16篇 |
国内免费 | 18篇 |
专业分类
耳鼻咽喉 | 6篇 |
儿科学 | 21篇 |
妇产科学 | 6篇 |
基础医学 | 37篇 |
口腔科学 | 10篇 |
临床医学 | 48篇 |
内科学 | 88篇 |
皮肤病学 | 3篇 |
神经病学 | 8篇 |
特种医学 | 131篇 |
外科学 | 20篇 |
综合类 | 8篇 |
预防医学 | 14篇 |
眼科学 | 18篇 |
药学 | 22篇 |
肿瘤学 | 20篇 |
出版年
2022年 | 1篇 |
2021年 | 3篇 |
2020年 | 1篇 |
2019年 | 1篇 |
2018年 | 4篇 |
2017年 | 6篇 |
2016年 | 7篇 |
2015年 | 2篇 |
2014年 | 6篇 |
2013年 | 10篇 |
2012年 | 7篇 |
2011年 | 9篇 |
2010年 | 8篇 |
2009年 | 15篇 |
2008年 | 3篇 |
2007年 | 16篇 |
2006年 | 8篇 |
2005年 | 9篇 |
2004年 | 2篇 |
2003年 | 2篇 |
2002年 | 7篇 |
2001年 | 8篇 |
2000年 | 10篇 |
1999年 | 10篇 |
1998年 | 33篇 |
1997年 | 18篇 |
1996年 | 24篇 |
1995年 | 17篇 |
1994年 | 21篇 |
1993年 | 13篇 |
1992年 | 5篇 |
1991年 | 6篇 |
1990年 | 11篇 |
1989年 | 21篇 |
1988年 | 32篇 |
1987年 | 12篇 |
1986年 | 15篇 |
1985年 | 14篇 |
1984年 | 11篇 |
1983年 | 7篇 |
1982年 | 9篇 |
1981年 | 4篇 |
1980年 | 11篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1977年 | 8篇 |
1976年 | 6篇 |
1973年 | 1篇 |
1947年 | 1篇 |
排序方式: 共有460条查询结果,搜索用时 15 毫秒
31.
羽叶三七叶中甙类成分的研究 总被引:3,自引:0,他引:3
从羽叶三七叶中分离到十三种甙类成分,经FAB-MS,13CNMR谱,双照射1HN-MR谱,1H-1H COSY谱及与标准品直接对照,证明十一种为已知化合物,分别为人参皂甙F1(Ⅰ),F2(Ⅱ),F3(Ⅲ),Rg2(Ⅳ),Ra(Ⅴ),Rd(Ⅵ),Rb1(Ⅷ),Rb3(Ⅷ),24(S)-假人参甙F11(Ⅸ),人参黄酮(Ⅹ)和珠子参甙F1(Ⅺ);另外两种为新的达玛烷型皂甙,命名为羽叶三七甙F1(Ⅻ)和F2(ⅫⅠ),并确定其化学结构。同时修正珠子参甙F3的结构。进一步阐明人参黄酮甙结构中的两个糖的连接方式。 相似文献
32.
Benedict CR; Ryan J; Todd J; Kuwabara K; Tijburg P; Cartwright J Jr; Stern D 《Blood》1993,81(8):2059-2066
Factor Xa is a central procoagulant enzyme, linking the intrinsic and extrinsic activation mechanisms to the final common pathway of coagulation. To assess its contribution to pathologic thrombosis, studies were performed in a canine coronary thrombosis model. Thrombus formation was initiated by the application of electric current via a needle electrode placed in the lumen of the left circumflex coronary artery. When 50% occlusion of the vessel developed, the current was stopped and animals received an intravenous bolus of either saline, bovine glutamyl-glycinyl-arginyl-factor Xa (Xai), a competitive inhibitor of factor Xa assembly into the prothrombinase complex, Factor X, or heparin. Animals infused with saline or factor X (300 micrograms/kg) developed total occlusion of the vessel due to a fibrin/platelet thrombus in 70 +/- 11 minutes (36 of 36 animals) and 74 +/- 13 minutes (8 of 8 animals), respectively. In contrast, infusion of Xai prevented thrombus formation completely at a dose of 300 micrograms/kg (8 of 8 animals). As the dose of Xai was decreased, its antithrombotic effect was diminished, with a patency rate of only 2 of 6 animals at a dose of 90 micrograms/kg. Xai at 300 micrograms/kg prevented the accumulation of 125I-fibrinogen/fibrin at the site of the coronary thrombus by approximately 63% and decreased deposition of 111In-labeled platelets by approximately 57%. Hemostatic parameters of animals infused with Xai demonstrated prolongation of the PT and dose- dependent increased extravascular bleeding tendency. These data indicate that factor Xa has a comparably important role in thrombus formation and extravascular hemostasis, and contrast with previous results in this same animal model in which IXai selectively prevented clotting in the coronary vasculature. 相似文献
33.
The palpation and enucleation of occult insulinomas (less than 15 mm) can be a difficult surgical problem even with good arteriographic localization. In the authors' limited experience, confirmation of arteriographic findings by pancreatic venous sampling provided little additional localizing information. However, if arteriography is negative or equivocal, venous sampling can indicate the segment of pancreas to be "blindly" resected if the adenoma is not palpable. Venous sampling may be misleading in polyendocrine syndromes because of the frequency of multiple adenomas and variable hormone production. 相似文献
34.
WL Craig CR Ramsay S Fielding ZH Krukowski 《Annals of the Royal College of Surgeons of England》2014,96(6):466-474
Introduction
This study describes variability of treatment for differentiated thyroid cancer among thyroid surgeons, in the context of changing patterns of thyroid surgery in the UK.Methods
Hospital Episodes Statistics on thyroid operations between 1997 and 2012 were obtained for England. A survey comprising six scenarios of varying ‘risk’ was developed. Patient/tumour information was provided, with five risk stratified or non-risk stratified treatment options. The survey was distributed to UK surgical associations. Respondent demographics were categorised and responses analysed by assigned risk stratified preference.Results
From 1997 to 2012, the Hospital Episode Statistics data indicated there was a 55% increase in the annual number of thyroidectomies with a fivefold increase in otolaryngology procedures and a tripling of cancer operations. Of the surgical association members surveyed, 264 respondents reported a thyroid surgery practice. Management varied across and within the six scenarios, and was not related consistently to the level of risk. Associations were demonstrated between overall risk stratified preference and higher volume practice (>25 thyroidectomies per year) (p=0.011), fewer years of consultant practice (p=0.017) and multidisciplinary team participation (p=0.037). Logistic regression revealed fewer years of consultant practice (odds ratio [OR]: 0.96/year in practice, 95% confidence interval [CI]: 0.922–0.997, p=0.036) and caseload of >25/year (OR 1.92, 95% CI: 1.044–3.522, p=0.036) as independent predictors of risk stratified preference.Conclusions
There is a substantial contribution to thyroid surgery in the UK by otolaryngology surgeons. Adjusting management according to established case-based risk stratification is not widely applied. Higher caseload was associated with a preference for management tailored to individual risk. 相似文献35.
1) By the action of thiouracil the follicular cell is not brought into the state of physiological inactivity and it shows signs of apparent secretion which differ however in details remarkably from the effective secretion stage. 2.) The quantity of follicular cells in mitosis is temporarily increased to the multiple. This disturbance is the result of the inhibition of caryokinesis in the stage of metaphase. 3) The absolute quantities of ribonucleic and of desoxyribonu-cleic acid are considerably reduced. 4) The ratio KNA/DNA shows a decrease to a fractional part of the normal value, according to the increase of the cell mass. 相似文献
36.
Left ventricular volumes measured by MR imaging 总被引:9,自引:0,他引:9
We assessed the potential of proton magnetic resonance (MR) imaging for accurately measuring left ventricular volumes using 15 latex casts of excised human left ventricles. The casts were submerged in water to stimulate the endocardial left ventricular cavity interface in in vivo imaging conditions. Tomographic image sections perpendicular to the long axis of the cast were obtained, spanning each cast from apex to base. Simpson's rule was used to calculate the cast volumes. Correlation between the actual cast volumes (as measured by the displacement method) and the calculated volumes using MR imaging for the 15 casts was excellent. Our data demonstrate that MR imaging accurately measures cardiac chamber volumes in this in vitro model. 相似文献
37.
38.
40年前创立的青少年糖尿病研究基金会((JDRF)是一个致力于通过支持研究来探寻1型糖尿病(TIDM)及其并发症治疗方法的组织.20世纪70年代有学者提出,TIDM和2型糖尿病(T2DM)的发病机制有根本的不同,T1DM与主要组织相容性复合体的人白细胞抗原(HLA)有独特相关性,有胰岛细胞自身抗体. 相似文献
39.
Strangulation in child abuse: CT diagnosis 总被引:2,自引:0,他引:2
The central nervous system is commonly affected in child abuse. Between April 1985 and July 1986 three infants were identified in whom the primary mode of injury had been strangulation. In each case computed tomography (CT) demonstrated a large cerebral infarction confined to vascular territories associated with small subdural hematomas. There was no history or visible evidence of significant head trauma. Autopsy of one infant confirmed the presence of a hemispheric infarct, thin subdural hematoma, and an area of subintimal hemorrhage in the carotid artery ipsilateral to the infarct. The remaining two patients survived with residual hemiparesis. CT findings of a large cerebral infarction with an associated subdural hematoma in an infant without a history of a significant trauma should suggest the possibility of child abuse and may be the primary manifestation of abuse in some patients. 相似文献
40.
Intracranial abnormalities in infants treated with extracorporeal membrane oxygenation: imaging with US and CT 总被引:1,自引:0,他引:1
Findings at neuroimaging in 100 consecutive infants treated with extracorporeal membrane oxygenation (ECMO) are presented. Imaging in these infants consisted of pretreatment cranial ultrasonography (US), daily US studies while on ECMO, and follow-up cranial computed tomography (CT) after treatment. There were findings of abnormalities in 43 patients. Thirty had intracranial bleeding, often of unusual extent and distribution. Thirteen additional infants had nonhemorrhagic abnormalities alone. Bleeding considered to be major was seen in 12% of infants. Large parenchymal hemorrhages and infarcts, cerebellar hemorrhages, and diffuse edema were the most significant abnormalities, with a 50% mortality (eight of 16 patients). No lateralization was noted with respect to distribution of bleeding sites or areas of nonhemorrhagic abnormalities. US was a sensitive but imperfect screening tool for intracranial abnormalities. Abnormalities missed with US included peripheral and small parenchymal lesions, subarachnoid hemorrhage, cerebral atrophy, and sagittal sinus thrombosis. 相似文献