全文获取类型
收费全文 | 1335640篇 |
免费 | 114688篇 |
国内免费 | 6363篇 |
专业分类
耳鼻咽喉 | 16702篇 |
儿科学 | 42992篇 |
妇产科学 | 36545篇 |
基础医学 | 183580篇 |
口腔科学 | 36293篇 |
临床医学 | 120586篇 |
内科学 | 278276篇 |
皮肤病学 | 31884篇 |
神经病学 | 110454篇 |
特种医学 | 55531篇 |
外国民族医学 | 274篇 |
外科学 | 210299篇 |
综合类 | 31526篇 |
现状与发展 | 2篇 |
一般理论 | 414篇 |
预防医学 | 106528篇 |
眼科学 | 28070篇 |
药学 | 93716篇 |
5篇 | |
中国医学 | 2227篇 |
肿瘤学 | 70787篇 |
出版年
2018年 | 13375篇 |
2017年 | 10631篇 |
2016年 | 12795篇 |
2015年 | 14297篇 |
2014年 | 19946篇 |
2013年 | 29733篇 |
2012年 | 36234篇 |
2011年 | 38885篇 |
2010年 | 24370篇 |
2009年 | 23902篇 |
2008年 | 36365篇 |
2007年 | 38775篇 |
2006年 | 39898篇 |
2005年 | 38491篇 |
2004年 | 36723篇 |
2003年 | 35822篇 |
2002年 | 33832篇 |
2001年 | 66054篇 |
2000年 | 67919篇 |
1999年 | 56593篇 |
1998年 | 16725篇 |
1997年 | 15017篇 |
1996年 | 16016篇 |
1995年 | 16232篇 |
1994年 | 15099篇 |
1993年 | 14153篇 |
1992年 | 47101篇 |
1991年 | 45750篇 |
1990年 | 43972篇 |
1989年 | 41815篇 |
1988年 | 38760篇 |
1987年 | 38082篇 |
1986年 | 35861篇 |
1985年 | 34637篇 |
1984年 | 26358篇 |
1983年 | 22109篇 |
1982年 | 13851篇 |
1981年 | 12447篇 |
1980年 | 11720篇 |
1979年 | 23544篇 |
1978年 | 17072篇 |
1977年 | 14388篇 |
1976年 | 13183篇 |
1975年 | 13722篇 |
1974年 | 16095篇 |
1973年 | 15397篇 |
1972年 | 14173篇 |
1971年 | 13037篇 |
1970年 | 11880篇 |
1969年 | 11102篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
911.
N D Hawass M G el-Badawi J A Fatani A A Meshari F S Abbas Y B Edrees F A Jabbar M Banna 《AJNR. American journal of neuroradiology》1987,8(4):691-695
To assess the length of the spinal cord relative to the vertebral column during fetal development, we performed translumbar myelograms on 340 spontaneously aborted fetuses. Of these, 146 were selected for study. There were 76 males and 70 females, with fetal age ranging from 7 to 33 weeks. Significant variation in the level of spinal cord termination was found in fetuses between 12 and 25 weeks gestational age. In fetuses between 25 and 33 weeks gestational age, the cord ended at or above the third lumbar vertebra. 相似文献
912.
Fine needle aspiration cytology of lesions of the head and neck and factors affecting outcome 总被引:1,自引:0,他引:1
K D Morton 《Scottish medical journal》1989,34(5):523-525
Fine Needle Aspiration Cytology (F.N.A.C.) has been used as a diagnostic tool by the ENT departments in Tayside since the end of 1985. This paper discusses the results of our initial experience with this and outlines some of the diagnostic pitfalls. This is a useful and accurate procedure with many advantages over diagnostic biopsy. 相似文献
913.
914.
Lung cancer is the leading cause of cancer deaths in both men and women in the United States. Treatment depends on the type and stage of lung cancer. For stage I and II cancer, surgery is usually the treatment of choice. Radiation therapy is used in patients who are considered poor risks for surgical resection. Intraoperative brachytherapy is an effective alternative to external irradiation in this group of patients. From 1958 to 1984, 55 patients with non-small-cell lung cancer were explored at Memorial Sloan Kettering Cancer Center and found to have surgical stage I or II tumors, which were considered to be unresectable mainly because of severe obstructive pulmonary disease precluding adequate resection. All these patients were treated with intraoperative brachytherapy at the time of the thoracotomy. Forty-four percent of these patients received in addition external irradiation, mainly to the mediastinum. The overall 5-year survival calculated by the Kaplan-Meier Method was 32%, and the local disease-free survival was 63%. Cox regression multivariant analysis demonstrated that there is a distinct subgroup with a better prognosis based on tumor site and patient's age--ie, patients who were younger than 58 years of age and had right-side lesions. 相似文献
915.
Inhibition by oral N-acetylcysteine of cigarette smoke-induced "bronchitis" in the rat 总被引:1,自引:0,他引:1
Specific pathogen-free rats were exposed to the cigarette smoke (CS) of 25 cigarettes daily for 14 days and concurrently given N-acetylcysteine (Nac) as 1% of their drinking water (average daily dose 973 mg/kg). The thickness of the epithelium was measured at four airway levels and the numbers of mucus-containing secretory cells, stained for neutral or acidic glycoprotein (NGP or AGP respectively), were counted in surface epithelium at eight airway levels. Cigarette smoke increased the thickness of the epithelium at three of the airway levels studied by between 37 and 72%. The number of secretory cells was increased at all airway levels distal to the upper trachea by between 102 and 421%. Secretory cells containing NGP were reduced in number but this was more than offset by a large increase in the number of secretory cells containing AGP at all airway levels. N-acetylcysteine inhibited CS-induced epithelial thickening. Nac also inhibited the CS-induced increase in the number of secretory cells with AGP, but had little effect on the CS-induced reduction in the number of cells with NGP. Thus, prophylactic oral N-acetylcysteine led to an overall inhibition of CS-induced mucous cell hyperplasia and epithelial hypertrophy. The results suggest a novel anti-inflammatory action for a drug with known mucolytic effects. 相似文献
916.
With some, but not all, types and intensities of exercise, lactate accumulates in the blood and in the muscles engaged in the exercise. A great deal of attention has been directed towards attempting to understand the dynamics of lactate production and removal at the onset of exercise, during exercise, and during the recovery process following exercise. It has been hoped that an unravelling of these events would provide a key to understanding cellular metabolism and its regulation during exercise. The purpose of this introductory paper to a symposium on lactate is to present a brief overview of some of the conditions that influence the rate and magnitude of lactate accumulation during exercise. It is pointed out that many conditions influence the rate and magnitude of the accumulation of lactate in blood and muscles. Included are diet, state of physical fitness, and the type and duration of the exercise. We have cautioned against trying to evaluate the state of oxygen delivery to muscle and the state of tissue oxygenation from the appearance of lactate in blood. We have pointed out the positive aspects of lactate production based on how it augments the cellular supply of ATP, thereby allowing for high intensity exercise, and also the negative aspects that develop as a result the reduction in pH which adversely influences many cellular processes essential for muscular activity. 相似文献
917.
Antigen presentation by a B-cell line transfected with cloned immunoglobulin heavy- and light-chain genes specific for a defined hapten. 总被引:5,自引:1,他引:4 下载免费PDF全文
M Watanabe D R Wegmann A Ochi N Hozumi 《Proceedings of the National Academy of Sciences of the United States of America》1986,83(14):5247-5251
The rearranged genes encoding immunoglobulin heavy (mu) and light (kappa) chains specific for the hapten 2,4,6-trinitrophenyl (Tnp) were introduced into a B-lymphoma line that bears surface IgG with an unknown specificity and expresses surface Ia molecules. A transformant expressing surface IgM specific for Tnp was obtained. The transformant was found to present Tnp-proteins to antigen (protein)-specific T cells far more efficiently than the parenteral B-lymphoma line. This artificial system, utilizing recombinant DNA technology and gene transfer, provides several approaches for the study of T-cell-B-cell interactions. 相似文献
918.
919.
920.