全文获取类型
收费全文 | 10868篇 |
免费 | 673篇 |
国内免费 | 48篇 |
专业分类
耳鼻咽喉 | 77篇 |
儿科学 | 292篇 |
妇产科学 | 257篇 |
基础医学 | 1814篇 |
口腔科学 | 324篇 |
临床医学 | 865篇 |
内科学 | 2615篇 |
皮肤病学 | 196篇 |
神经病学 | 973篇 |
特种医学 | 227篇 |
外科学 | 1270篇 |
综合类 | 49篇 |
一般理论 | 10篇 |
预防医学 | 810篇 |
眼科学 | 154篇 |
药学 | 785篇 |
中国医学 | 23篇 |
肿瘤学 | 848篇 |
出版年
2023年 | 98篇 |
2022年 | 71篇 |
2021年 | 356篇 |
2020年 | 203篇 |
2019年 | 303篇 |
2018年 | 349篇 |
2017年 | 237篇 |
2016年 | 265篇 |
2015年 | 340篇 |
2014年 | 376篇 |
2013年 | 466篇 |
2012年 | 744篇 |
2011年 | 756篇 |
2010年 | 425篇 |
2009年 | 336篇 |
2008年 | 625篇 |
2007年 | 533篇 |
2006年 | 612篇 |
2005年 | 545篇 |
2004年 | 486篇 |
2003年 | 434篇 |
2002年 | 401篇 |
2001年 | 210篇 |
2000年 | 191篇 |
1999年 | 190篇 |
1998年 | 86篇 |
1997年 | 54篇 |
1996年 | 69篇 |
1995年 | 64篇 |
1994年 | 40篇 |
1993年 | 40篇 |
1992年 | 154篇 |
1991年 | 141篇 |
1990年 | 119篇 |
1989年 | 129篇 |
1988年 | 110篇 |
1987年 | 100篇 |
1986年 | 98篇 |
1985年 | 92篇 |
1984年 | 71篇 |
1983年 | 59篇 |
1982年 | 37篇 |
1980年 | 33篇 |
1979年 | 73篇 |
1978年 | 40篇 |
1977年 | 39篇 |
1976年 | 33篇 |
1975年 | 33篇 |
1973年 | 33篇 |
1970年 | 31篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
11.
Intraductal papillary mucinous tumor (IPMT) of the pancreas is characterized by slow growth and a relatively favorable prognosis, however, invasive cancer originating in an IPMT is associated with a poor prognosis. Although various parameters in imaging modalities have been advocated to differentiate between benign IPMN and malignant ones, it is not easy to obtain definite diagnosis based on these parameters. Peroral pancreatoscopy (POPS) allows a clear and direct visualization of the pancreatic duct, providing useful information regarding tumor nature in IPMT. The authors have studied the usefulness of POPS in the diagnosis of IPMT. Nevertheless, its usefulness is not necessarily widely accepted and the significance of POPS is still controversial. In this review, the authors intended to address the diagnostic value of POPS and to clarify its role in the diagnosis of IPMT. The authors think treatment of IPMT can be improved by introducing POPS because the determination of surgical procedure as well as the area of resection based on the preoperative diagnosis of the involvement of the main pancreatic duct and branch duct is inevitable. 相似文献
12.
Erika E Forbes Douglas E Williamson Neal D Ryan Boris Birmaher David A Axelson Ronald E Dahl 《Neuropsychopharmacology》2006,59(1):24-30
BACKGROUND: Changes in the hypothalamic-pituitary-adrenal (HPA) axis, as evidenced by patterns of cortisol secretion, have been of interest in understanding depression and anxiety disorders across the life span. Previous studies of pediatric depression have pointed to the period around sleep onset as a key time point for observing alterations in cortisol secretion associated with affective disorders. Evidence also indicates that pubertal development may influence the expression of HPA dysregulation. We hypothesized that adolescents with depression and youth with anxiety disorders exhibit elevated peri-sleep-onset cortisol. METHODS: Plasma cortisol was sampled every 20 min around sleep onset from children and adolescents with major depressive disorder (n = 116), anxiety disorders (n = 32), or no history of psychiatric disorder (control; n = 76). Sleep onset was determined by polysomnography. Classification of participants as children or adolescents was based on Tanner staging of pubertal maturation. RESULTS: Children with anxiety disorders had higher peri-sleep-onset cortisol than children with depression or control children. Adolescents with depression had marginally higher peri-sleep-onset cortisol than control adolescents and significantly higher peri-sleep-onset cortisol than children with depression. CONCLUSIONS: Depression and anxiety are associated with altered cortisol secretion around sleep onset, and these changes appear to be influenced by pubertal maturation. 相似文献
13.
Nobuyuki Inoue Kouji Nagaike Shinichi Ishihara Mitsuhiko Nakamura Toshio Kuroshima 《Digestive endoscopy》2006,18(2):134-137
Background: For management of bowel obstruction due to colorectal cancer, endoscopic trans‐anal decompression technique has been first reported by Lelcuk et al. in 1986 using balloon dilatation technique. Since then, various types of trans‐anal decompression tubes have been clinically used for patients suffering from left side obstructing colorectal cancer as an emergent decompressing device. At present, two types of trans‐anal ileus tube (trans‐anal decompression tube) have been available for clinical use, but they have two main problems that are late colon perforations caused by the tip of the tube and tube obstruction by stool. Methods: Analysis on three late colon perforations experienced with the use of conventional devices drew possible improvements to make a trans‐anal ileus tube less harmful. To overcome the pitfalls inherent to conventional tubes, the author has developed an improved trans‐anal ileus tube with a balloon installed at the very end of the tube (‘balloon‐tipped type’) made of silicone, measuring 1200 or 1700 mm in total length and 22 Fr in outer diameter. It has been used for 12 cases with obstructing colorectal cancer etc. and its outcomes were compared with those obtained by the use of conventional trans‐anal ileus tube. Results: No late perforations have been encountered, but tube obstruction did occur in one of 12 cases. Conclusion: The new trans‐anal ileus tube with a balloon installed at the tip of ileus tube is considered to be safer and especially effective in preventing late colon perforation and tube obstruction. 相似文献
14.
H Ishihara M Bjeljac D Straumann Y Kaku P Roth Y Yonekawa 《Minimally invasive neurosurgery》2006,49(3):168-172
OBJECTIVE: A safe entry zone to tegmental lesions was identified based on intraoperative electrophysiological findings, the compound muscle action potentials (CMAP) from the extraocular muscles, and anatomic considerations. This entry zone is bordered caudally by the intramesencephalic path of the trochlear, laterally by the spinothalamic tract, and rostrally by the caudal margin of the brachium of the superior colliculus. METHODS: Four intrinsic midbrain lesions were operated upon via the safe entry zone using the infratentorial paramedian supracerebellar approach. All lesions involved the tegmentum and included an anaplastic astrocytoma, a metastatic brain tumor, a radiation necrosis, and a cavernous angioma. CMAP were bilaterally monitored from the inferior recti (for oculomotor function) and superior oblique (for trochlear nerve function) muscles. RESULTS: In three of four cases, CMAP related to the oculomotor nerve were obtained upon stimulation at the cavity wall after removal of the tumor. Stimulation at the surface of the quadrigeminal plate, however, did not cause any CMAP response. Using this monitoring as an indicator, the lesions were totally removed. CONCLUSIONS: In the surgery of tegmental lesions, CMAP monitoring from extraocular muscles is particularly helpful to prevent damage to crucial neural structures during removal of intrinsic lesions, but less so to select the site of the medullary incision. The approach via the lateral part of the colliculi is considered to be a safe route to approach the tegmental lesions. 相似文献
15.
16.
Isabella Sch?ll George Boltz-Nitulescu Erika Jensen-Jarolim 《Journal of controlled release》2005,104(1):1-27
For the treatment of infectious diseases, cancer and allergy, the directed induction of an appropriate immune response is the ultimate goal. Therefore, with the development of pure, often very small proteins, peptides or DNA by molecular biology techniques, the research for suitable adjuvants or delivery systems became increasingly important. Particle formulations are made of a variety of materials, including lipids, proteins or amino acids, polysaccharides, polyacrylic substances or organic acids. Microparticles serve as vehicles and provide a depot for the entrapped or coupled antigen. The release occurs in a pulsatile or continuous manner, a feature, which is well controllable for many particulate systems. Particles attract antigen presenting cells to the administration site, thereby guaranteeing the efficient presentation of the antigen to the immune system. Importantly, particles also protect the entrapped substance. This is especially necessary after oral application to avoid gastric or tryptic breakdown. In this article, the design and construction of different antigen delivery systems and their immune effects, with special focus on the suitability for allergy treatment, are discussed. 相似文献
17.
Immunohistochemical and immunoelectron microscopical characterization of cerebrovascular and senile plaque amyloid in aged dogs'' brains 总被引:2,自引:0,他引:2
Tokuhiro Ishihara Toshikazu Gondo Mutsuo Takahashi Fumiya Uchino Shu-Ichi Ikeda David Allsop Kohzoh Imai 《Brain research》1991,548(1-2):196-205
Immunohistochemical and immunoelectron microscopical studies were carried out on 28 aged dogs' brains. Amyloid deposits were seen in the arteries and capillaries in the leptomeninges and in superficial areas of the cortices in 19 (67.9%) of the 28 dogs (10-22 years of age). Immunohistochemically, these amyloid deposits were reactive for anti-beta/A4 antibody. Additionally, a variable number of parenchymal deposits with diffuse beta/A4-immunoreactivity (diffuse plaques) was also noted throughout the cerebral cortex in 24/28 dogs (85.7%). However, these plaque lesions were undetectable in Congo red staining. Electron microscopically, amyloid fibrils, measuring 10 nm in width, were located mainly in the tunica media of the arteries, and in less involved vessels they tended to be present among collagen fibres in the adventitia and smooth muscle cells in the outer layer of the media. The plaque lesions appeared to contain sparse aggregations of amyloid fibrils. In immunoelectron microscopical examinations, all amyloid fibrils in both blood vessels and plaques were selectively labelled by gold particles. These findings indicate that aged dogs can provide a useful experimental model for research into the beta/A4-type of cerebral amyloidosis commonly seen in Alzheimer's disease. 相似文献
18.
19.
20.
Activation of AMPK in rat hypothalamus participates in cold-induced resistance to nutrient-dependent anorexigenic signals 总被引:3,自引:0,他引:3
Erika A. Roman Maristela Cesquini Graziela R. Stoppa José B. Carvalheira Márcio A. Torsoni Lício A. Velloso 《The Journal of physiology》2005,568(3):993-1001
The exposure of homeothermic animals to a cold environment leads to a powerful activation of orexigenic signalling which is accompanied by molecular and functional resistance to insulin-induced inhibition of feeding. Recent evidence suggests that AMPK participates in nutrient-dependent control of satiety and adiposity. The objective of the present study was to evaluate the effect of cold exposure upon the molecular activation of AMPK signalling in the hypothalamus of rats. Immunoblotting demonstrated that cold exposure per se is sufficient for inducing, on a time-dependent basis, the molecular activation of the serine/threonine kinase AMP-activated protein kinase (AMPK) and inactivation of the acetyl-CoA carboxylase (ACC). These molecular phenomena were accompanied by resistance to nutrient-induced inactivation of AMPK and activation of ACC. Moreover, cold-exposure led to a partial inhibition of a feeding-induced anorexigenic response, which was paralleled by resistance to insulin-induced suppression of feeding. Finally, cold exposure significantly impaired insulin-induced inhibition of AMPK through a mechanism dependent on the molecular cross-talk between phosphatidylinositol-3(PI3 )-kinase/Akt and AMPK. In conclusion, increased feeding during cold exposure results, at least in part, from resistance to insulin- and nutrient-dependent anorexigenic signalling in the hypothalamus. 相似文献