全文获取类型
收费全文 | 205631篇 |
免费 | 4820篇 |
国内免费 | 1005篇 |
专业分类
耳鼻咽喉 | 2916篇 |
儿科学 | 7825篇 |
妇产科学 | 6078篇 |
基础医学 | 26320篇 |
口腔科学 | 6101篇 |
临床医学 | 16374篇 |
内科学 | 36491篇 |
皮肤病学 | 4818篇 |
神经病学 | 12450篇 |
特种医学 | 11007篇 |
外国民族医学 | 105篇 |
外科学 | 30596篇 |
综合类 | 2371篇 |
现状与发展 | 5篇 |
一般理论 | 2篇 |
预防医学 | 17107篇 |
眼科学 | 4700篇 |
药学 | 14624篇 |
3篇 | |
中国医学 | 509篇 |
肿瘤学 | 11054篇 |
出版年
2021年 | 593篇 |
2018年 | 3899篇 |
2017年 | 4213篇 |
2016年 | 3559篇 |
2015年 | 5269篇 |
2014年 | 4870篇 |
2013年 | 4038篇 |
2012年 | 10595篇 |
2011年 | 5604篇 |
2010年 | 2723篇 |
2009年 | 4255篇 |
2008年 | 2500篇 |
2007年 | 3291篇 |
2006年 | 3434篇 |
2005年 | 11573篇 |
2004年 | 12974篇 |
2003年 | 8619篇 |
2002年 | 3762篇 |
2001年 | 4674篇 |
2000年 | 2114篇 |
1999年 | 6160篇 |
1998年 | 673篇 |
1992年 | 6937篇 |
1991年 | 7143篇 |
1990年 | 7387篇 |
1989年 | 7006篇 |
1988年 | 6515篇 |
1987年 | 6274篇 |
1986年 | 5981篇 |
1985年 | 5277篇 |
1984年 | 3612篇 |
1983年 | 2939篇 |
1982年 | 1024篇 |
1981年 | 788篇 |
1980年 | 856篇 |
1979年 | 3846篇 |
1978年 | 2390篇 |
1977年 | 1805篇 |
1976年 | 1578篇 |
1975年 | 2494篇 |
1974年 | 3122篇 |
1973年 | 2753篇 |
1972年 | 2776篇 |
1971年 | 2757篇 |
1970年 | 2581篇 |
1969年 | 2479篇 |
1968年 | 2243篇 |
1967年 | 2167篇 |
1966年 | 1907篇 |
1965年 | 1136篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
141.
Chromosomentranslokationen in Tumoren führen nicht selten zur Ausbildung von Fusionsgenen, die für Proteine mit onkogenen Eigenschaften codieren können. Mukoepidermoidkarzinome sind charakterisiert durch eine Translokation t(11;19), die in 60% der untersuchten Tumoren vorkommt. Diese chromosomale Umlagerung führt zu einem Fusionsgen, das aus dem Exon 1 des MECT 1-Gens und den Exons 2–5 des MAML 2-Gens zusammengesetzt ist. In der Folge bildet sich ein Fusionstranskript, wodurch unabhängig von Notch-Liganden eine Aktivierung der Transkription von HES 1, einem Notch-Zielgen, erfolgt. Durch die veränderte Funktion von MAML 2 kommt es zur Unterbrechung des NOTCH-Signaltransduktionsweges, was einen neuen Mechanismus in der Tumorgenese vermuten lässt. Der Nachweis der Translokation mittels FISH und/oder RT-PCR könnte von erheblichem diagnostischem und möglicherweise auch prognostischem Interesse sein. Zuvor müssen allerdings die molekularen Ereignisse, die einem scheinbar identischen chromosomalen Rearrangement in Warthin-Tumoren zugrunde liegen, geklärt werden. Warthin-Tumoren sind gutartige Speicheldrüsentumoren mit einer vom Mukoepidermoidkarzinom abweichenden Histomorphologie und Histogenese. 相似文献
142.
A young patient had an auriculo-ventricular block and a distal myopathy with muscle biopsy findings suggestive of inclusion body myositis. What was most unusual was the presence of numerous sarcoplasmic bodies identified as desmin by electron microscopy and immunocytochemistry. The nosological situation of this condition is discussed. 相似文献
143.
144.
145.
146.
The efficiency of the Racal Airstream helmet respirator in improving peak expiratory flow rates (PEFR) and symptoms (dyspnea, wheezing, and cough) in aluminum potroom workers with respiratory complaints was assessed in 19 workers. Peak expiratory flow readings and symptom recording from a 2-week working period with use of the respirator were compared with a period when the 3M 9906 disposable mask was used. The study was designed as a randomized, parallel, cross-over study with five or six daily measurements of PEFR and daily symptom recording. A significant number of workers (15) had a higher mean peak flow in the helmet period than in the nonhelmet period (p less than 0.01); symptoms did not improve significantly in the helmet period. Objective evidence of respiratory protection was observed for the group of workers as a whole, but the effect on symptoms as well as individual effect on peak flow was minor in the majority of the workers. 相似文献
147.
Serum digoxin-like factor was detected in infants of diabetic mothers who were insulin-dependent or diet controlled. No statistical difference was found between the serum digoxin-like factor levels of the infants of diabetic mothers and the controls. 相似文献
148.
The question of the necessity of in-patient facilities of the area of (child and) adolescent neuropsychiatry is to be discussed further. The extremely optimistic views on this question of approximately 20 years ago cannot be maintained for the examined area and the examination time. In the LNKH Valduna/Vorarlberg, an establishment that was intended exclusively for adults until 1987, from 1980-1984 (evaluated in detail) and from 1984-1987 a further 60 minors were admitted. The exact evaluation shows that the conspicuousnesses of behaviour of a main group was so clear each time that it could not be treated elsewhere and certainly not in outpatient facilities. In the examined group the amount of patients with behaviour and socialization disorders outweighed by far the psychoses, also a high percentage of patients was multi morbid and/or had multiple handicaps. The resulting conclusion seems to us to be the necessity of setting-up a specific in-patients treatment unit for this group of patients with sufficient infrastructure. 相似文献
149.
Surgically-obtained tissue specimens from 41 patients with ventricular aneurysm were studied electron microscopically. The tissue from the resected aneurysms showed substantially varied morphological differences. In some, there were extensive regions of scar containing increased fibrotic material and few cells, in others there were also larger contiguous regions of myocardium with an essentially normal appearance. In the preserved myocardial regions, the cardiac cells showed moderate hypertrophy. There was an increase in contractile substance in parallel with an increase in mitochondria and enlargement of the nucleus with frequent waves and invaginations in the cell membrane. The cells at the marginal regions between fibrous tissue and preserved myocardium were frequently isolated from adjacent cells. In particular, when the isolated cells were completely surrounded by fibrous tissue, clear degeneration was apparent. These cells showed mainly a fibrillolysis with dissolution of the cross-bands and loss of the entire contractile apparatus. In compensation, occasionally there was proliferation of other cell structures, especially the free sarcoplasmatic reticulum. The hypertrophy of the still intact myocardial cells is considered compensatory for the infarct-incurred loss of tissue. The degenerative appearance is mainly attributable to fibrous tissue invasion. The diminished oxygen supply, compromised or abolished impulse conduction, loss of function and passive stretch during systole may be regarded as causes of the degeneration. 相似文献
150.
A prospective study was performed on seven male and eight female patients with normal hepatobiliary findings to investigate the effect of 20 mg nifedipine on cholecystokinin-induced gallbladder contraction. Each patient received 1 IDU (Ivy dog unit) cholecystokinin per kg body weight intravenously on two consecutive days, with additional administration of 20 mg nifedipine sublingually on the second day. Gallbladder volumes were assessed by ultrasonography over a period of 25 minutes. Cholecystokinin induced a maximal reduction in the mean initial volume of 56.8 +/- 3.6%. After nifedipine, this volume change was significantly reduced to 30.9 +/- 5.1% (p less than 0.001). Thus our data suggest for the first time that the calcium-channel-blocking agent nifedipine can have an effect on human gallbladder kinetics. 相似文献