全文获取类型
收费全文 | 15545篇 |
免费 | 984篇 |
国内免费 | 88篇 |
专业分类
耳鼻咽喉 | 100篇 |
儿科学 | 364篇 |
妇产科学 | 368篇 |
基础医学 | 1919篇 |
口腔科学 | 314篇 |
临床医学 | 1519篇 |
内科学 | 3603篇 |
皮肤病学 | 219篇 |
神经病学 | 1724篇 |
特种医学 | 690篇 |
外科学 | 2301篇 |
综合类 | 66篇 |
一般理论 | 6篇 |
预防医学 | 1093篇 |
眼科学 | 297篇 |
药学 | 892篇 |
中国医学 | 33篇 |
肿瘤学 | 1109篇 |
出版年
2024年 | 22篇 |
2023年 | 192篇 |
2022年 | 285篇 |
2021年 | 500篇 |
2020年 | 382篇 |
2019年 | 449篇 |
2018年 | 527篇 |
2017年 | 411篇 |
2016年 | 496篇 |
2015年 | 488篇 |
2014年 | 666篇 |
2013年 | 844篇 |
2012年 | 1392篇 |
2011年 | 1365篇 |
2010年 | 714篇 |
2009年 | 601篇 |
2008年 | 1063篇 |
2007年 | 1028篇 |
2006年 | 895篇 |
2005年 | 918篇 |
2004年 | 796篇 |
2003年 | 681篇 |
2002年 | 621篇 |
2001年 | 96篇 |
2000年 | 75篇 |
1999年 | 103篇 |
1998年 | 134篇 |
1997年 | 75篇 |
1996年 | 89篇 |
1995年 | 63篇 |
1994年 | 50篇 |
1993年 | 56篇 |
1992年 | 54篇 |
1991年 | 44篇 |
1990年 | 31篇 |
1989年 | 38篇 |
1988年 | 35篇 |
1987年 | 23篇 |
1986年 | 23篇 |
1985年 | 34篇 |
1984年 | 20篇 |
1983年 | 31篇 |
1982年 | 14篇 |
1981年 | 21篇 |
1980年 | 11篇 |
1979年 | 11篇 |
1972年 | 14篇 |
1971年 | 19篇 |
1969年 | 10篇 |
1968年 | 20篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
71.
Down-regulation of nitric oxide synthase-2 and cyclooxygenase-2 pathways by p53 in squamous cell carcinoma 总被引:7,自引:0,他引:7
下载免费PDF全文
![点击此处可从《The American journal of pathology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Gallo O Schiavone N Papucci L Sardi I Magnelli L Franchi A Masini E Capaccioli S 《The American journal of pathology》2003,163(2):723-732
The goal of this study was to analyze the correlation between inducible nitric oxide synthase (iNOS) and COX-2 activities and p53 gene status in head and neck squamous cell carcinomas (HNSCCs) in vivo and in vitro. In a series of 43 HNSCCs we observed an up-regulation of both iNOS and COX-2 pathways in tumor tissues and both activities were correlated each other (rs = 0.612 and P = 0.0002). We also found that p53-mutated HNSCCs (25 cases, 58.1%) showed higher levels of iNOS activity and cGMP in comparison with wild-type p53 tumors (18 cases, 41.9%) (P = 0.0005 and P = 0.01), as well as higher iNOS immunohistochemical expression (P = 0.03). Analogously, higher PgE2 levels were documented in p53-mutated HNSCCs when compared with wild-type p53 tumors (P = 0.015) and COX-2 protein expression was higher in p53-mutated HNSCCs (P = 0.007). A431 cancer cells expressing a p53 temperature-sensitive mutant showed an approximately 1.9- and 2.6-fold decrease in spontaneous NO(2-)/NO(3-) and PgE2 synthesis at permissive temperature, respectively, when compared with the same cells at nonpermissive temperature (P 相似文献
72.
73.
Brunetti-Pierri N Andreucci MV Tuzzi R Vega GR Gray G McKeown C Ballabio A Andria G Meroni G Parenti G 《American journal of medical genetics. Part A》2003,(2):164-168
Partial trisomy of the long arm of chromosome 10 is a well-defined but rare syndrome. Clinical features of this chromosomopathy are a distinctive dysmorphic appearance, developmental delay, growth retardation, and in some cases, abnormalities of the extremities and renal, cardiac and ocular anomalies. This report describes a neonate with symmetric growth retardation and multiple dysmorphic features, in whom chromosomal analysis revealed a partial trisomy of chromosome 10q with a monosomy of the 13q34 region. The phenotype shares many common features with previously published cases. In addition to the typical features, our case also shows renal hypoplasia with early renal insufficiency and some genital anomalies. 相似文献
74.
75.
76.
77.
Steroid synthesis and metabolism in the nervous system: Trophic and protective effects 总被引:14,自引:0,他引:14
Michael Schumacher Yvette Akwa Rachida Guennoun Françoise Robert Florencia Labombarda Franck Désarnaud Paul Robel Alejandro F. De Nicola Etienne-Emile Baulieu 《Journal of neurocytology》2000,29(5-6):307-326
Steroids influence the activity and plasticity of neurons and glial cells during early development, and they continue to exert trophic and protective effects in the adult nervous system. Steroids are produced by the gonads and adrenal glands and reach the brain, the spinal cord and the peripheral nerves via the bloodstream. However, some of them, named neurosteroids, can also be synthesized within the nervous system. They include pregnenolone, progesterone, dehydroepiandrosterone and their reduced metabolites and sulfate esters. Little is known concerning the regulation of steroid synthesis in the nervous system, which involves interactions between different cell types. For example, the synthesis of progesterone by Schwann cells in peripheral nerves is regulated by a diffusible neuronal signal. Neurotrophic and neuroprotective effects of steroids have been documented both in cell culture and in vivo. PROG plays an important role in the neurological recovery from traumatic injury of the brain and spinal cord by mechanisms involving protection from excitotoxic cell death, lipid peroxydation and the induction of specific enzymes. After transection of the rat spinal cord, PROG increases the number of nitric oxide synthase expressing astrocytes immediately above and below the lesion. PROG also plays an important role in the formation of new myelin sheaths. This has been shown in the regenerating mouse sciatic nerve after lesion and in cocultures of sensory neurons and Schwann cells. PROG promotes myelination by activating the expression of genes coding for myelin proteins. The modulation of neurostransmitter receptors, in particular the type A -aminobutyric acid, the N-methyl-D-aspartate and the sigma 1 receptors, is involved in the psychopharmacological effects of steroids and allows to explain their anticonvulsant, anxiolytic, antidepressive and sedative effects as well as their influence on memory. Pregnenolone sulfate has been shown to reverse age-related deficits in spatial memory performance and to have protective effects on memory in different models of amnesia. 相似文献
78.
Anna Maria Buccoliero Chiara Francesca Gheri Francesca Castiglione Franco Ammannati Pasquale Gallina Antonio Taddei Francesca Garbini Duccio Rossi Degl'Innocenti Luisa Arganini Nicola Di Lorenzo Pasquale Mennonna Gian Luigi Taddei 《Applied immunohistochemistry & molecular morphology》2007,15(3):353-357
One of the most common chromosomal regions implicated in the meningiomas tumorigenesis is 22q12 where the neurofibromatosis 2 (NF2) gene resides. The NF2 tumor-suppressor gene encodes for the merlin/schwannomin protein, which is responsible for the inherited disease neurofibromatosis 2. NF2 gene mutations predominantly occur in transitional and fibroblastic meningiomas, whereas the meningothelial variant is less affected. Secretory meningioma is an infrequent meningioma subtype. Its most typical morphologic feature is the presence of intracytoplasmic or extracytoplasmic round hyaline, eosinophilic, and periodic acid Shiff-positive bodies in a lesion frequently otherwise classifiable as meningothelial meningioma. This study reviews the immunohistochemical merlin expression in 14 consecutive secretory meningiomas. Our purpose was to investigate if secretory meningiomas, analogous to meningothelial meningiomas, follow a molecular route of pathogenesis independent of the neurorofibromatosis 2 gene-associated pathway. All meningiomas showed positive immunocoloration involving the majority of the hyaline inclusions and secretory cells; in 12 (86%) meningiomas, a positive immunoreaction was also documented in nonsecretory tumoral cells. Our results may indicate a molecular, besides morphologic, similarity between secretory and meningothelial meningiomas: the almost constant merlin immunohistochemical expression in our series gives evidence for a possible NF2 gene-independent pathogenesis in secretory meningiomas. 相似文献
79.
Synergistic effect of interleukin-2 and a vaccine of irradiated melanoma cells transfected to secrete staphylococcal enterotoxin A 总被引:4,自引:0,他引:4
We have previously reported that immunization of mice with melanoma cells transfected to secrete the superantigen, Staphylococcal enterotoxin A (SEA), increased the production of antibodies to the B700 melanoma antigen, stimulated the production of endogenous interleukin 2 (IL-2), activated the expression of CD4, CD8 and CD25 T cell markers and enhanced NK cell activity. Now we show that immunization of mice with a vaccine of irradiated sea-transfected melanoma cells coupled with IL-2 therapy was even more effective in inhibiting the growth of primary melanoma tumors and the development of lung metastases than was the irradiated melanoma cell vaccine alone or IL-2 alone. The morphological and immunological effectiveness of the therapy was dose-dependent on IL-2. 相似文献
80.
Gene therapy is defined as the introduction of a therapeutic gene into a cell, whose expression can lead to a cure of a disease or offer a transient advantage for tissue growth and regeneration. The delivery of genes can be undertaken for a number of purposes, usually it is attempted to enhance or add a function to a cell or a tissue or to delete or reduce another function. In this brief overview we describe various vehicles and techniques that have been developed to deliver therapeutic genes into cells, such as viral vectors and physical/chemical gene delivery methods including naked DNA and particle-mediated gene transfer, the microseeding technique and the application of lipids. Furthermore we review the potential utility of gene therapy from the perspective of a reconstructive surgeon. Several tissues will be discussed, particularly muscle, tendon, nerve, bone, skin and wounds. 相似文献