全文获取类型
收费全文 | 1233篇 |
免费 | 100篇 |
国内免费 | 9篇 |
专业分类
耳鼻咽喉 | 9篇 |
儿科学 | 32篇 |
妇产科学 | 47篇 |
基础医学 | 154篇 |
口腔科学 | 34篇 |
临床医学 | 120篇 |
内科学 | 320篇 |
皮肤病学 | 26篇 |
神经病学 | 104篇 |
特种医学 | 29篇 |
外科学 | 150篇 |
综合类 | 26篇 |
预防医学 | 43篇 |
眼科学 | 63篇 |
药学 | 100篇 |
中国医学 | 4篇 |
肿瘤学 | 81篇 |
出版年
2024年 | 3篇 |
2023年 | 22篇 |
2022年 | 49篇 |
2021年 | 69篇 |
2020年 | 40篇 |
2019年 | 55篇 |
2018年 | 54篇 |
2017年 | 44篇 |
2016年 | 37篇 |
2015年 | 42篇 |
2014年 | 61篇 |
2013年 | 61篇 |
2012年 | 98篇 |
2011年 | 113篇 |
2010年 | 59篇 |
2009年 | 41篇 |
2008年 | 69篇 |
2007年 | 68篇 |
2006年 | 50篇 |
2005年 | 61篇 |
2004年 | 46篇 |
2003年 | 45篇 |
2002年 | 37篇 |
2001年 | 16篇 |
2000年 | 10篇 |
1999年 | 15篇 |
1998年 | 7篇 |
1997年 | 7篇 |
1996年 | 3篇 |
1995年 | 3篇 |
1993年 | 4篇 |
1992年 | 4篇 |
1991年 | 5篇 |
1990年 | 6篇 |
1989年 | 6篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1985年 | 4篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1975年 | 1篇 |
1974年 | 3篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1970年 | 1篇 |
1969年 | 2篇 |
1966年 | 1篇 |
排序方式: 共有1342条查询结果,搜索用时 0 毫秒
71.
We investigated whether N1 and P2 auditory-evoked responses are modulated by the spectral complexity of musical sounds in pianists and non-musicians. Study participants were presented with three variants of a C4 piano tone equated for temporal envelope but differing in the number of harmonics contained in the stimulus. A fourth tone was a pure tone matched to the fundamental frequency of the piano tones. A simultaneous electroencephalographic/magnetoencephalographic recording was made. P2 amplitude was larger in musicians and increased with spectral complexity preferentially in this group, but N1 did not. The results suggest that P2 reflects the specific features of acoustic stimuli experienced during musical practice and point to functional differences in P2 and N1 that relate to their underlying mechanisms. 相似文献
72.
73.
p130Rb2 and p27kip1 cooperate to control mobilization of angiogenic progenitors from the bone marrow
Vidal A Zacharoulis S Guo W Shaffer D Giancotti F Bramley AH de la Hoz C Jensen KK Kato D MacDonald DD Knowles J Yeh N Frohman LA Rafii S Lyden D Koff A 《Proceedings of the National Academy of Sciences of the United States of America》2005,102(19):6890-6895
Neoangiogenesis involves both bone marrow-derived myelomonocytic and endothelial progenitor cells as well as endothelial cells coopted from surrounding vessels. Cytokines induce these cells to proliferate, migrate, and exit the cell cycle to establish the vasculature; however, which cell cycle regulators play a role in these processes is largely unknown. Here, we report that mice lacking the cell cycle inhibitors p130 and p27 show defects in tumor neoangiogenesis, both in xenografts and spontaneously arising tumors. This defect is associated with impaired mobilization of endothelial and myelomonocytic angiogenic progenitors from the bone marrow. This article documents the role of these molecules in angiogenesis and further suggests that cell expansion and mobilization from the bone marrow of angiogenic precursors are separable events. 相似文献
74.
Patterns of uveitis in a tertiary eye care center in Iran 总被引:1,自引:0,他引:1
Soheilian M Heidari K Yazdani S Shahsavari M Ahmadieh H Dehghan M 《Ocular immunology and inflammation》2004,12(4):297-310
PURPOSE: To identify the distribution and characteristics of new uveitis referrals to a tertiary eye care center in Tehran. METHODS: A three-year prospective study was carried out to obtain information on 544 new patients referred with uveitis. A complete ophthalmologic examination was performed in all cases; a routine set of tests and an additional battery of directed workup were conducted when indicated. RESULTS: Mean age was 32.3 years. There was no significant sex predominance. The most common forms of uveitis were anterior (38.4%) vs. other anatomical forms, chronic (62.1%) vs. acute (28.3%), nongranulomatous (85.5%) vs. granulomatous (14.5%), and noninfectious (83.5%) vs. infectious (16.5%). With regard to etiology, 45.5% were idiopathic, 19.9% were due to specific ocular disease, and 37.3% were associated with systemic disorders. Behcet's disease was the most common noninfectious disease and toxoplasmosis the most common infectious entity. The most prevalent causes were idiopathic, Fuchs' heterochromic iridocylitis, and seronegative spondyloarthropathies in anterior uveitis; toxoplasmosis, Eales disease, and toxocariasis in posterior uveitis; idiopathic, sarcoidosis, and multiple sclerosis in intermediate uveitis; and, finally, Behcet's disease, idiopathic, and Vogt-Koyanagi-Harada syndrome in panuveitis. The most frequent cause in patients under 16 years of age was pars planitis. Over 80% of the patients belonged to middle-to-upper socioeconomic classes. Uveitis significantly affected patients' lives in 63.1% of the cases. CONCLUSION: Although the current study was performed at a referral center, it may reflect to some extent the different distribution of uveitis in Iran and probably other Middle Eastern countries. Some entities such as presumed ocular histoplasmosis were not found, cytomegalovirus retinitis and birdshot chorioretinopathy were extremely rare, and HLA-B27-associated iridocyclitis was less commonly observed. In contrast, Behcet's disease, Fuchs' heterochromic iridocyclitis, Eales disease, and toxocariasis were among the more prevalent entities. 相似文献
75.
76.
Background
Attention-deficit hyperactivity disorder is an early-onset, clinically heterogenous disorder of inattention, hyperactivity, and impulsiveness. The diagnosis and treatment of attention-deficit hyperactivity disorder continues to raise controversy, and, there is also an increase in treatment options. In this 6-week double blind, placebo controlled-trial, we assessed the effects of zinc plus methylphenidate in the treatment of children with attention deficit hyperactivity disorder. To the best of our knowledge, this study is the first double blind and placebo controlled clinical trial assessing the adjunctive role of zinc in ADHD. 相似文献77.
A 32-year-old woman presented with an abrupt, localized loss of scalp hair that occurred on the previous day. Her nails, skin, and mucosae were normal. On the vertex of the scalp, there was a circular patch of alopecia; the hairs were broken at approximately equal lengths above the skin surface. Several erythematous macules were seen in the affected area, but scale, twisted hair, and exclamation-mark hairs were not present. Further examination revealed the presence of ants on the scalp. This patient is one of several referred to our department presenting with hair loss associated with hair-cutter ant invasion. 相似文献
78.
Rodrigues S Attoub S Nguyen QD Bruyneel E Rodrigue CM Westley BR May FE Thim L Mareel M Emami S Gespach C 《Oncogene》2003,22(29):4488-4497
Trefoil peptides (TFFs) are now considered as scatter factors, proinvasive and angiogenic agents acting through cyclooxygenase-2 (COX-2)- and thromboxane A2 receptor (TXA2-R)-dependent signaling pathways. As expression and activation levels of the epidermal growth factor receptor (EGFR) predict the metastatic potential of human colorectal cancers, the purpose of this study was to establish whether the EGF receptor tyrosine kinase (EGFR-TK) contributes to cellular invasion induced by TFFs in kidney and colonic cancer cells. Both the dominant negative form of the EGFR (HER-CD533) and the EGFR-TK inhibitor ZD1839 (Iressa) abrogated cellular invasion induced by pS2, spasmolytic polypeptide (SP) and the src oncogene, but not by ITF and the TXA2-R. Similarly, EGFR-TK inhibition by ZD1839 reversed the invasive phenotype promoted by the constitutively activated form of the EGFR (EGFRvIII) and the EGFR agonists transforming growth factor alpha (TGFalpha), amphiregulin and EGF. We also provide evidence that TFFs, EGFRvIII, and TGFalpha trigger common proinvasive pathways using the PI3'-kinase and Rho/Rho- kinase cascades. These findings identify the EGFR-TK as a key signaling element for pS2- and SP-mediated cellular invasion. It is concluded that although pS2, SP and ITF belong to the same family of inflammation- and cancer-associated regulatory peptides, they do not control identical signaling networks. 相似文献
79.
Tumor vasculature address book: identification of stage-specific tumor vessel zip codes by phage display 总被引:4,自引:0,他引:4
Using in vivo phage display technology with murine tumorigenesis models, two reports have identified peptide motifs that selectively home to distinct molecular vascular targets in a tumor type- and stage-specific manner (Hoffman et al., 2003 and Joyce et al., 2003 [this issue of Cancer Cell]). By probing the surface-protein repertoire of these unique vascular beds, a pioneering draft of a molecular roadmap to decipher the heterogeneity of the vascular system in the context of carcinogenic progression has been plotted. Analysis of these phage peptides that differentially home to dysplastic or invasive tumor vasculature will lay the foundation for identifying unique functional tumor vascular-specific motifs that could potentially be applied to targeted therapeutic and imaging modalities. 相似文献
80.
Cooperation of fuzzy segmentation operators for correction aliasing phenomenon in 3D color Doppler imaging 总被引:2,自引:0,他引:2
The study described in this paper concerns natural object modeling in the context of uncertain, imprecise and inconsistent representation. We propose a fuzzy system which offers a global modeling of object properties such as color, shape, velocity, etc. This modeling makes a transition from a low level reasoning (pixel level), which implies a local precise but uncertain representation, to a high level reasoning (region level), inducing a certain assignment. So, we use fuzzy structured partitions characterizing these properties. At this level. each property will have its own global modeling. Then, these different models are merged for decision making. Our approach was tested with several applications. In particular, we show here its performance in the area of blood flow analysis from 3D color Doppler images in order to quantify and study the development of this flow. We present methods that detect and correct aliasing phenomenon, i.e. inconsistent information. At first, the flow space is partitioned into fuzzy sectors where each sector is defined by a center, an angle and a direction. In parallel, the velocity information carried by the pixels is classified into fuzzy classes. Then, by combining these two partitions, we obtain the velocity distribution into sectors. Moreover, for each found path (from the first sector to the last one), we locate and correct inconsistent velocities by applying global rules. After extracting some meaningful sector features, the fuzzy modeling, applied to the aliasing correction, makes it possible to simplify and synthesize the blood flow direction. 相似文献