全文获取类型
收费全文 | 20015篇 |
免费 | 1671篇 |
国内免费 | 35篇 |
专业分类
耳鼻咽喉 | 265篇 |
儿科学 | 698篇 |
妇产科学 | 521篇 |
基础医学 | 2950篇 |
口腔科学 | 406篇 |
临床医学 | 2268篇 |
内科学 | 3896篇 |
皮肤病学 | 222篇 |
神经病学 | 1522篇 |
特种医学 | 830篇 |
外国民族医学 | 3篇 |
外科学 | 2477篇 |
综合类 | 527篇 |
一般理论 | 25篇 |
预防医学 | 2082篇 |
眼科学 | 268篇 |
药学 | 1586篇 |
2篇 | |
中国医学 | 7篇 |
肿瘤学 | 1166篇 |
出版年
2021年 | 284篇 |
2020年 | 175篇 |
2019年 | 291篇 |
2018年 | 301篇 |
2017年 | 214篇 |
2016年 | 249篇 |
2015年 | 297篇 |
2014年 | 423篇 |
2013年 | 618篇 |
2012年 | 842篇 |
2011年 | 919篇 |
2010年 | 491篇 |
2009年 | 434篇 |
2008年 | 762篇 |
2007年 | 814篇 |
2006年 | 790篇 |
2005年 | 799篇 |
2004年 | 733篇 |
2003年 | 671篇 |
2002年 | 679篇 |
2001年 | 602篇 |
2000年 | 647篇 |
1999年 | 532篇 |
1998年 | 261篇 |
1997年 | 226篇 |
1996年 | 249篇 |
1995年 | 228篇 |
1994年 | 199篇 |
1993年 | 192篇 |
1992年 | 491篇 |
1991年 | 493篇 |
1990年 | 457篇 |
1989年 | 427篇 |
1988年 | 411篇 |
1987年 | 418篇 |
1986年 | 422篇 |
1985年 | 424篇 |
1984年 | 317篇 |
1983年 | 275篇 |
1982年 | 207篇 |
1981年 | 173篇 |
1979年 | 305篇 |
1978年 | 228篇 |
1977年 | 202篇 |
1976年 | 168篇 |
1975年 | 177篇 |
1974年 | 180篇 |
1973年 | 189篇 |
1972年 | 167篇 |
1971年 | 163篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Integrins are a complex family of non-covalently linked heterodimeric glycoproteins which function as cell adhesion molecules, interacting with extracellular matrix molecules such as laminin, fibronectin, vitronectin, and collagen, and also having a role in intercellular adhesion. Each integrin subfamily is characterized by a common beta chain associated with variable alpha chains. We have examined, using immunohistological methods, the expression of the VLA (very late activation) family comprising beta 1 in association with alpha 1-6, and also alpha 6 in association with beta 4, the LFA beta chain beta 2, and the vitronectin receptor, in association with beta 1 or beta 5 and as the complex alpha v beta 3. Cryostat sections of normal pancreas, pancreatic adenocarcinomas, and ampullary tumours were studied together with six pancreatic carcinoma cell lines. Normal pancreas showed expression of beta 1 in all parenchyma. alpha 2 and alpha 6 had a similar distribution whereas alpha 3 expression was confined to ducts, including the very smallest radicles. Staining along the basement membranes of ducts was seen with beta 4 and the anti-vitronectin alpha v chain receptor antibody 13C2. Islet cells failed to stain with any antibody. No staining of epithelial components was seen with antibodies to alpha 1, alpha 4, alpha 5, or to the alpha v beta 3 form of the vitronectin receptor (beta 3 and alpha v beta 3 using the antibody 23C6). Pancreatic adenocarcinomas and ampullary tumours showed expression of alpha 2, alpha 3, alpha 6, beta 1, beta 4, and the vitronectin receptor (alpha v associated with beta 1 or beta 5).(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
102.
The distribution of somatomedins in the nervous system of the cat and their release following neural stimulation 总被引:3,自引:0,他引:3
V R Sara K Uvn?s-Moberg B Uvn?s K Hall L Wetterberg B Posloncec M Goiny 《Acta physiologica Scandinavica》1982,115(4):467-470
Recent evidence suggests a regulatory role in the nervous system for somatomedins. The present study, using a somatomedin radioreceptorassay which primarily detects insulin-like growth factors 1 and 2, shows that somatomedins are widely distributed throughout the nervous system of the cat. Whilst somatomedins were present in all CNS regions, the highest concentration occurred in the hypothalamus followed by cerebral cortex. In the spinal cord, the dorsal roots contained twice the concentration found in the ventral roots. Activity was also present in the sympathetic ganglia, vagus nerve and sciatic nerves. Following electrical stimulation of the brachial and sciatic nerves somatomedins were released into perfusates from extirpated cut limbs. These findings suggest that somatomedins may be neuroregulatory hormones. 相似文献
103.
A new autosomal recessive syndrome of characteristic facies, joint contractures, skeletal abnormalities, and normal development: second report with further clinical delineation
下载免费PDF全文

Ajay Gupta Christine M Hall Yvonne F Ransley Victoria A Murday 《Journal of medical genetics》1995,32(10):809-812
We describe a girl of Pakistani origin, born to consanguineous parents, with a multiple congenital anomaly (MCA) syndrome. This is the second report confirming an apparently new autosomal recessive syndrome reported earlier by van den Ende et al in 1992. The hallmarks of this MCA syndrome include characteristic facies with blepharophimosis, narrow, beaked nose, hypoplastic maxilla with or without cleft palate and everted lower lip, arachnodactyly, self-limiting congenital joint contractures, peculiar skeletal abnormalities, and normal growth and development. Further clinical and radiological delineation of the syndrome in this report suggests that the term “Marden-Walker-like syndrome without psychomotor retardation”, used in the first report to describe this condition, does not accurately reflect its clinical picture. The overall prognosis in this syndrome seems good. 相似文献
104.
105.
106.
Dynamic imaging of the lungs using x-ray phase contrast 总被引:4,自引:0,他引:4
Lewis RA Yagi N Kitchen MJ Morgan MJ Paganin D Siu KK Pavlov K Williams I Uesugi K Wallace MJ Hall CJ Whitley J Hooper SB 《Physics in medicine and biology》2005,50(21):5031-5040
High quality real-time imaging of lungs in vivo presents considerable challenges. We demonstrate here that phase contrast x-ray imaging is capable of dynamically imaging the lungs. It retains many of the advantages of simple x-ray imaging, whilst also being able to map weakly absorbing soft tissues based on refractive index differences. Preliminary results reported herein show that this novel imaging technique can identify and locate airway liquid and allows lung aeration in newborn rabbit pups to be dynamically visualized. 相似文献
107.
108.
Hall M Buysse DJ Nowell PD Nofzinger EA Houck P Reynolds CF Kupfer DJ 《Psychosomatic medicine》2000,62(2):227-230
OBJECTIVE: Previous studies have not evaluated the clinical correlates of the electroencephalographic spectral profile in patients with insomnia. In the preliminary study described here, we evaluated the extent to which symptoms of stress and depression are associated with subjective sleep complaints and quantitative measures of sleep in individuals with chronic insomnia. METHODS: Subjects were 14 healthy adults who met criteria for primary insomnia as specified in the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders. Measures of stress, depression, and subjective sleep quality were collected before subjects participated in a two-night laboratory sleep series. We hypothesized that elevated symptoms of stress and depression would be associated with subjective sleep complaints and electroencephalographic evidence of hyperarousal during sleep. Hyperarousal during sleep was defined as decreases in delta power and elevations in alpha and beta power throughout non-rapid eye movement sleep, and symptoms of stress were defined as the tendency to experience stress-related intrusive thoughts and the interaction between intrusion tendency and the number of recent stressful events (subjective stress burden). RESULTS: A stronger tendency to experience stress-related intrusive thoughts was associated with greater sleep complaints and a trend toward higher beta power, whereas increases in subjective stress burden were associated with decreases in delta power. In addition, elevations in subclinical symptoms of depression were associated with greater sleep complaints and elevations in alpha power. CONCLUSIONS: Observed relationships among symptoms of stress, depression, subjective sleep complaints, and electroencephalographic power may be relevant to the discrepancy between subjective and objective measures of sleep in patients with insomnia and may be more broadly applicable to sleep complaints in association with stressful life events and major depression. 相似文献
109.
110.
A peptide with a molecular weight of about 5 000 has previously been shown to affect the output of semen in frogs and probably also in mammals. This sperm-releasing substance is not part of any known gonadotropic hormone. The distribution of this substance has been investigated using whole-body autoradiography. Radioactive material is incorporated into the epididymis, the adenohypophysis and probably also into the ovary. 相似文献