全文获取类型
收费全文 | 934843篇 |
免费 | 66587篇 |
国内免费 | 1345篇 |
专业分类
耳鼻咽喉 | 13083篇 |
儿科学 | 24430篇 |
妇产科学 | 23324篇 |
基础医学 | 133290篇 |
口腔科学 | 28291篇 |
临床医学 | 80730篇 |
内科学 | 183733篇 |
皮肤病学 | 19391篇 |
神经病学 | 72489篇 |
特种医学 | 36932篇 |
外国民族医学 | 79篇 |
外科学 | 152632篇 |
综合类 | 18090篇 |
现状与发展 | 1篇 |
一般理论 | 238篇 |
预防医学 | 61965篇 |
眼科学 | 21379篇 |
药学 | 72749篇 |
3篇 | |
中国医学 | 2168篇 |
肿瘤学 | 57778篇 |
出版年
2018年 | 9021篇 |
2017年 | 7062篇 |
2016年 | 7814篇 |
2015年 | 8900篇 |
2014年 | 12058篇 |
2013年 | 17596篇 |
2012年 | 24232篇 |
2011年 | 25180篇 |
2010年 | 14893篇 |
2009年 | 14354篇 |
2008年 | 24704篇 |
2007年 | 25823篇 |
2006年 | 26575篇 |
2005年 | 25527篇 |
2004年 | 24670篇 |
2003年 | 23719篇 |
2002年 | 23251篇 |
2001年 | 54814篇 |
2000年 | 56637篇 |
1999年 | 47024篇 |
1998年 | 10755篇 |
1997年 | 9494篇 |
1996年 | 9618篇 |
1995年 | 8947篇 |
1994年 | 8299篇 |
1993年 | 7609篇 |
1992年 | 35537篇 |
1991年 | 33960篇 |
1990年 | 32789篇 |
1989年 | 31913篇 |
1988年 | 29035篇 |
1987年 | 28293篇 |
1986年 | 26327篇 |
1985年 | 25182篇 |
1984年 | 17858篇 |
1983年 | 15165篇 |
1982年 | 7821篇 |
1981年 | 6793篇 |
1979年 | 15817篇 |
1978年 | 10624篇 |
1977年 | 9076篇 |
1976年 | 7897篇 |
1975年 | 8661篇 |
1974年 | 10486篇 |
1973年 | 9898篇 |
1972年 | 9384篇 |
1971年 | 8877篇 |
1970年 | 8471篇 |
1969年 | 7955篇 |
1968年 | 7222篇 |
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
171.
The authors investigated the effect on the brain of red blood cells that had been modified by contrast media. Rat blood was mixed with an equivolume of contrast media, and up to 200 microL of the mixture was infused to the internal carotid artery of the rat. Evans blue was administered intravenously to assess the integrity of the blood-brain barrier (BBB). Immediately after the death of the animal, or 2.5 hours after the infusion, the brain was removed for evaluation of the degree of BBB destruction and edema. Extensive destruction of the BBB, cerebral edema, and death of the animals were induced by infusion of blood mixed with an ionic contrast medium, such as diatrizoate and iothalamate, which deformed red blood cells. Microscopic observation showed atrophy and necrosis of nerve cells and decomposition of nerve fibers in the affected area of the brain. Cerebral damage was not observed in rats injected with blood mixed with a nonionic contrast medium such as iopamidol, iopromide, or metrizamide, which had less effect on red blood cells. Cerebral damage also was observed in the rats injected with blood mixed with a hyperosmotic solution of mannitol, as well as washed red blood cells mixed with an ionic contrast medium. This study's results indicate that hyperosmotic ionic contrast media affect red blood cells and cause disturbance in cerebral circulation. 相似文献
172.
173.
C G Watson T Kucala G Angulski P Vassar 《The Journal of nervous and mental disease》1987,175(1):34-40
This project was designed to test two hypotheses drawn from a new formulation explaining the exaggerated winter birthrate among hospitalized schizophrenics. The first is that the supposed exaggerated winter birthrate among process schizophrenics actually represents a reduction in spring-fall births caused by prenatal exposure to infectious diseases during the preceding winter--i.e., a high prenatal death rate in process preschizophrenic fetuses. The second is that the level of negative symptoms in survivors at risk for schizophrenia who were born after winters with high infectious disease rates is exaggerated. The findings provided some tentative support for this formulation. Compared with counterparts born after low-disease winters, schizophrenics born after winters with high disease incidences tended to show lower (more reactive) scores on a measure of the process-reaction dimension but higher anhedonia scores. 相似文献
174.
T Iino N Toyosaki T Katsuki T Noda T Natsume T Yaginuma S Hosoda M Furuse 《Clinical nuclear medicine》1987,12(9):688-693
The perfusion territories in polar representations of stress Tl-201 rotational myocardial imaging in patients with angina pectoris who had one diseased coronary segment were analyzed. The lesions proximal or distal to the first major septal perforator in left anterior descending arteries were detected by the presence or absence of defects at the base of the anterior septum. Right coronary artery lesions were detected by the presence of defects at the basal posterior septum, in contrast to the preservation of myocardial uptake at this portion in lesions of the left circumflex artery. The specific defect patterns were detected in cases with lesions at the first diagonal, obtuse marginal, and posterolateral branches. Recognition of these defects in the polar maps allows detailed detection of diseased coronary arterial branches. 相似文献
175.
We report an 80-year-old Japanese male with four primary malignant tumors: malignant melanoma, prostatic cancer, malignant lymphoma, and renal cell carcinoma, which occurred in that respective order. The combination of malignant melanoma and malignant lymphoma is rare. The patient was treated with BCG after an operation for malignant melanoma. He was also treated with cobalt 60 irradiation after an operation for prostatic cancer. We also discuss other reports of multiple malignant tumors and suggest some possible causes of this patient's primary malignant tumors. 相似文献
176.
A prospective study of 20 normal subjects was undertaken to determine the effect of three ankle positions (active dorsiflexion, active plantar flexion, natural or rest position) on comfort and facilitation of quadriceps contraction in isometric strengthening in a supine position with the hip and knee fully extended. Surface EMG activity was found to be greatest for the vastus lateralis followed by the vastus medialis and least for the rectus femoris. Equal facilitation was apparent with either active ankle dorsiflexion or plantar flexion. Both were superior to the natural (rest) position. In situations where isometric quadriceps exercises are required, the authors recommend either active ankle dorsiflexion or plantar flexion to facilitate quadriceps strengthening. The choice between the two positions should be based on patient comfort. 相似文献
177.
178.
179.
The concentration of microsomal cytochromes P-450, and of protein in the homogenate, cytosol and microsomes were measured in the liver, kidney and duodenal mucosa of healthy well-fed male and female camels, sheep and goats. For comparison, data from the liver of male and female rats were also obtained. The protein concentrations in the tissues of adult animals were broadly similar in the four species. The concentration of cytochromes P-450 was highest in the liver, followed by the kidney, then the duodenal mucosa in all the species. No cytochromes P-450 were detected in the tissues of immature (less than 1 mo) male goats, whereas the female goat had the highest concentrations of these enzymes in the liver and kidney when compared with the respective tissues in the other species studied. Males had higher activity of cytochromes P-450 than females in the three tissues, except in the duodenal mucosa of sheep, where males had lower activity than females. In camel liver and sheep kidney, the amount of cytochromes P-450 were similar in the two sexes. The present results suggest that the mature female goat is the species best equipped to handle xenobiotics which are detoxified by the cytochromes P-450 and other drug metabolizing enzymes in diseased or malnourished animals is suggested as these two conditions are known to modify drug metabolizing enzymes. 相似文献
180.