首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   552篇
  免费   21篇
  国内免费   96篇
耳鼻咽喉   2篇
儿科学   37篇
基础医学   43篇
口腔科学   19篇
临床医学   106篇
内科学   150篇
皮肤病学   7篇
神经病学   7篇
特种医学   108篇
外科学   23篇
综合类   35篇
预防医学   21篇
眼科学   4篇
药学   80篇
肿瘤学   27篇
  2023年   3篇
  2022年   1篇
  2021年   7篇
  2020年   2篇
  2019年   5篇
  2018年   4篇
  2017年   4篇
  2016年   5篇
  2015年   4篇
  2014年   8篇
  2013年   19篇
  2012年   7篇
  2011年   6篇
  2010年   26篇
  2009年   25篇
  2008年   15篇
  2007年   60篇
  2006年   17篇
  2005年   24篇
  2004年   6篇
  2003年   8篇
  2002年   8篇
  2001年   16篇
  2000年   10篇
  1999年   10篇
  1998年   41篇
  1997年   38篇
  1996年   29篇
  1995年   29篇
  1994年   27篇
  1993年   38篇
  1992年   6篇
  1991年   7篇
  1990年   12篇
  1989年   26篇
  1988年   24篇
  1987年   15篇
  1986年   16篇
  1985年   14篇
  1984年   9篇
  1983年   3篇
  1982年   7篇
  1981年   4篇
  1980年   10篇
  1979年   2篇
  1978年   3篇
  1977年   7篇
  1976年   1篇
  1975年   1篇
排序方式: 共有669条查询结果,搜索用时 15 毫秒
91.
The COVID-19 pandemic had a notable impact on the psychological well-being of a large part of the population, putting them at risk of developing depressive symptoms, different levels of anxiety disorders, and posttraumatic stress disorder (PTSD). One group considered to be at high risk are Nursing students; they were affected as learning strategies changed and clinical practices were cancelled. This study attempts to assess the psychological impact COVID-19 pandemic had on Nursing students and to explore the sociodemographic differences that can be risk factors for mental health disturbance. The psychological impact was evaluated using the Impact of Event Scale-Revised (IES-R) and Hospital Anxiety and Depression Scale (HADS). The study took place 4 months after the state of alarm was declared over in Spain. From a total sample of 304 Nursing students, 26.7%, 39.8%, and 15.5% showed PTSD, anxiety, and depression symptoms, respectively. Severe levels of psychological impact have been associated with being a female, a smoker, and feeling fear and stress. Having a relative test positive has been linked to lower anxiety levels while being afraid or stressed to higher anxiety levels. Being a female, co-habit with friends and feeling stress have been associated with higher depression levels.  相似文献   
92.
猪脑钠素及其类似物的合成   总被引:1,自引:0,他引:1  
以固相多肽合成方法合成了猪的二十六肽脑钠素(BNP)和它的一个类似物(Mpr4,D-Ala6,13)-BNP(4-24)-NH2,保护肽用HF裂解除去保护基、在碱性条件下空气氧化形成二硫桥后,粗产物经凝胶过滤和高效液相色谱分离纯化,均有与天然脑钠素相同的活性。合成肽相对于树脂初始取代量的产率分别为9.56%和11.03%。  相似文献   
93.
顺铂聚乳酸微球的药物释放特性及肝动脉栓塞研究   总被引:5,自引:0,他引:5  
对顺铂聚乳酸微球进行了体外药物释放和家犬肝动脉栓塞研究。该微球粒径范围为50~200μm,平均粒径为115.76±35.94μm,顺铂含量为37.16%(W/W);体外药物释放机制符合Higuchi方程;肝动脉栓塞后8h,肝组织顺铂浓度高达21.55±12.18μg/g,明显高于肝动脉灌注顺铂组:3.16±0.09μg/g(P<0.05);肝动脉栓塞组的顺铂血浓峰值、各取血点浓度及曲线下面积AUC皆低于肝动脉灌注顺铂组。可望达到提高栓塞部位的药物疗效,降低全身毒副反应的作用。  相似文献   
94.
BACKGROUND: Growing interest is nowadays focused on the quality of life of elderly people who survive with chronic diseases. Coronary heart disease (CHD) is one of the most common diseases among the elderly and may have an unfavourable impact on the patient's emotional well-being. OBJECTIVES: We aimed to describe the prevalence of depression and the occurrence of depressive symptoms among elderly CHD patients, with a special emphasis on the relations between depression and the severity of CHD, and to find out the possible association between CHD and depression. METHODS: The study was carried out at the health centre of the municipality of Lieto, in south-west Finland. The study population consisted of 488 community-dwelling men and 708 women, over 64 years old, from among whom the participants with CHD (89 men and 73 women) were selected, and for whom 178 male and 146 female sex- and age- matched controls (free of CHD) were drawn from the population. CHD patients were selected on the basis of the presence of angina pectoris or a past myocardial infarction. Depressive symptoms were measured with the Zung Self-rating Depression Scale. Depression was described in relation to the severity of dyspnoea and chest pain among patients. The associations between depression and age, health, health behaviour, drugs, functional ability and social, psychosocial and environmental factors were analysed by logistic regression analyses. RESULTS: The prevalence of depression was 29% among male patients and 20% among female patients. Depression was significantly more common among male CHD patients than among male controls (P = 0.011). Among women, depression was not associated with CHD. Earlier, depression had gone undiagnosed among many CHD patients and controls, especially male patients. Among male CHD patients, depression was associated with more severe dyspnoea, but no similar association was found among female CHD patients. Among men the occurrence of CHD, physical disability, widowhood or divorce, and among women previous clinical depression, physical disability and the use of angiotensin-converting enzyme (ACE) inhibitors, were associated with depression. CONCLUSION: Depression is common among patients with CHD. It seems that CHD is not an independent factor in the aetiology of depression among the elderly. The association of CHD with depression among men is explained by the acute or chronic psychic stress caused by CHD. It may be that the more complicated the patient's CHD, the more probable is the presence of depression.   相似文献   
95.
人参叶中微量新皂甙-La的分离与鉴定   总被引:4,自引:0,他引:4  
前已报道从人参(Panax ginseng C.A.Meyer)叶中分到三种微量新皂甙。在继续研究的基础上,又得到一个微量新皂甙,命名为人参皂甙-La(ginsenoside-La)。人参皂甙-La,无色针晶(MeOH),[α]D~(20)—18.4(Pyridine-d_5)。负离子FAB-MS  相似文献   
96.
注射用双黄连与几种抗生素联合体外抑菌活性的研究   总被引:11,自引:0,他引:11  
目的:探讨注射用双黄连与抗生素联合使用的临床意义。方法:参考中国药典抗生素微生物检定法,测定注射用双黄连与头孢拉定等6种抗生素配伍使用后对金葡菌及克雷白氏肺炎杆菌的抑菌圈直径的变化。结果:注射用双黄连与氨苄青霉素、普鲁卡因青霉素、头孢唑啉钠及红霉素配伍后对金葡萄的体外抑菌效果明显增强;与头孢拉定、头孢唑啉钠及普鲁卡因青霉素配伍后对克氏肺炎杆菌的体外抑菌效果有不同程度的增强。结论:对于不同的细菌感染  相似文献   
97.
98.
A 54-year-old man was treated with weekly 24-h infusion of high-dose 5-fluorouracil (2600 mg/m2) and leucovorin (100 mg/m2) for metastatic colon cancer. At first, he tolerated the treatment well and no significant toxicity was identified. After a total of eight courses of treatment, a stable disease was observed, but mild shortness of breath was found on occasion. The patient had no previous history of cardiac disease and the heart performance assessed by left ventricular ejection fraction before treatment was normal. Unfortunately, acute pulmonary edema with lethal cardiogenic shock occurred during the ninth course of treatment, in spite of intensive medical treatment. The chest X-ray showed extreme cardiomegaly. Repeated assessment of his heart function by echocardiogram and ventricular ejection fraction revealed a very poor cardiac performance. Toxic cardiogenic shock during weekly 24-h infusion of high-dose 5-fluorouracil and leucovorin is extremely rare. To the best of our knowledge, no case has been reported in the English literature. We report a case and the relevant literature about the incidence, clinical picture and possible pathophysiology on 5-fluorouracil-related cardioxicity is reviewed.   相似文献   
99.
To investigate the influence of asymptomatic bacteriuria inchildhood on subsequent pregnancy, we reviewed the outcome of139 pregnancies in 88 women who were first identified duringa programme of screening schoolgirls for asymptomatic bacteriuriacarried out between 1970–1972 [1]. Data were analysedfor the following groups: 50 pregnancies in 28 women with knownrenal scars (group 1); 16 pregnancies in 14 women with normalkidneys and reflux (group 2); 73 pregnancies in 46 women withnormal urinary tracts (group 3); 139 healthy controls. Women in group 1 had a 3.3-fold increased relative risk of hypertension(p < 0.01) and a 7.6-fold increased risk of pre-eclampsia(p< 0.05) compared to controls, and a higher rate of obstetricinterventions, including emergency caesarean section. Womenin groups 2 and 3 appeared to carry a slightly increased riskof hypertension during the last trimester (RR = 1.8) but therewere no significant differences in this or the incidence ofpre-eclampsia or mode of delivery. Bacteriuria was more prevalentin all index groups compared to controls (37 per cent vs. 8per cent, p < 0.01) and included four cases of acute pyelonephritisin the study group. Fetal outcome was satisfactory in all cases.These results suggest that women with renal scars are at riskof hypertension and pre-eclampsia during pregnancy but thatmodern obstetric care minimizes these risks.  相似文献   
100.
白首乌化学成分的研究   总被引:11,自引:0,他引:11  
自白首乌主要品种耳叶牛皮消(Cynanchum auriculatum Royle ex Wight)根中首次分得三个已知甾体酯型甙元:告达亭(caudatin),开德甙元(kidjolanin),萝藦甙元(Metaplexigenin)和一种新的二苯酮衍生物(Ⅳ),经光谱分析推定其结构为2,6,2′,5′-四羟基,3-乙酰基,6′-甲基二苯酮,命名白首乌二苯酮。  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号