全文获取类型
收费全文 | 5931篇 |
免费 | 443篇 |
国内免费 | 51篇 |
专业分类
耳鼻咽喉 | 52篇 |
儿科学 | 132篇 |
妇产科学 | 134篇 |
基础医学 | 1099篇 |
口腔科学 | 97篇 |
临床医学 | 513篇 |
内科学 | 1512篇 |
皮肤病学 | 178篇 |
神经病学 | 595篇 |
特种医学 | 83篇 |
外科学 | 568篇 |
综合类 | 26篇 |
一般理论 | 3篇 |
预防医学 | 443篇 |
眼科学 | 82篇 |
药学 | 460篇 |
中国医学 | 21篇 |
肿瘤学 | 427篇 |
出版年
2024年 | 5篇 |
2023年 | 91篇 |
2022年 | 219篇 |
2021年 | 405篇 |
2020年 | 192篇 |
2019年 | 265篇 |
2018年 | 286篇 |
2017年 | 183篇 |
2016年 | 224篇 |
2015年 | 225篇 |
2014年 | 307篇 |
2013年 | 347篇 |
2012年 | 492篇 |
2011年 | 520篇 |
2010年 | 271篇 |
2009年 | 231篇 |
2008年 | 362篇 |
2007年 | 353篇 |
2006年 | 313篇 |
2005年 | 298篇 |
2004年 | 237篇 |
2003年 | 212篇 |
2002年 | 198篇 |
2001年 | 23篇 |
2000年 | 12篇 |
1999年 | 34篇 |
1998年 | 29篇 |
1997年 | 22篇 |
1996年 | 13篇 |
1995年 | 10篇 |
1994年 | 2篇 |
1993年 | 4篇 |
1992年 | 7篇 |
1991年 | 4篇 |
1990年 | 5篇 |
1988年 | 1篇 |
1987年 | 4篇 |
1983年 | 1篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1975年 | 2篇 |
1974年 | 1篇 |
1973年 | 3篇 |
1969年 | 1篇 |
1968年 | 1篇 |
1963年 | 1篇 |
1931年 | 1篇 |
1928年 | 1篇 |
排序方式: 共有6425条查询结果,搜索用时 31 毫秒
71.
Natalia S. Kozhevnikova Tatyana I. Gorbunova Andrey S. Vorokh Marina G. Pervova Alexsander Ya. Zapevalov Victor I. Saloutin Oleg N. Chupakhin 《Sustainable Chemistry and Pharmacy》2019
The chemical stability and hydrophobic nature of chloroarenes make them a persistent environmental hazard. Modeling of 1,2,4-trichlorobenzene (1,2,4-TCB) degradation in alcohol-water solution under UV irradiation was carried out with the aim of probing how the 1,2,4-TCB might behave in the environment. The photocatalytic activity of both bare TiO2 and TiO2 doped by colloidal CdS nanoparticles synthesized by the sol-gel method has been investigated in the processes of 1,2,4-TCB photodegradation in the aqueous protic solvent. Non-sensitized TiO2 cannot be regarded as catalyst for the 1,2,4-TCB photodecomposition. On the contrary, the CdS/TiO2 composite accelerated the 1,2,4-TCB photodegradation process. The concentration of CdS/TiO2 was shown to effect on the 1,2,4-TCB photolysis mechanisms, which resulted in the quantitative ratios of the 1,2,4-TCB photolysis products. 相似文献
72.
Michela Colombo Serena Galletti Silvia Garavelli Natalia Platonova Alessandro Paoli Andrea Basile Elisa Taiana Antonino Neri Raffaella Chiaramonte 《Oncotarget》2015,6(29):26826-26840
Despite recent therapeutic advances, multiple myeloma (MM) is still an incurable neoplasia due to intrinsic or acquired resistance to therapy. Myeloma cell localization in the bone marrow milieu allows direct interactions between tumor cells and non-tumor bone marrow cells which promote neoplastic cell growth, survival, bone disease, acquisition of drug resistance and consequent relapse. Twenty percent of MM patients are at high-risk of treatment failure as defined by tumor markers or presentation as plasma cell leukemia. Cumulative evidences indicate a key role of Notch signaling in multiple myeloma onset and progression. Unlike other Notch-related malignancies, where the majority of patients carry gain-of-function mutations in Notch pathway members, in MM cell Notch signaling is aberrantly activated due to an increased expression of Notch receptors and ligands; notably, this also results in the activation of Notch signaling in surrounding stromal cells which contributes to myeloma cell proliferation, survival and migration, as well as to bone disease and intrinsic and acquired pharmacological resistance. Here we review the last findings on the mechanisms and the effects of Notch signaling dysregulation in MM and provide a rationale for a therapeutic strategy aiming at inhibiting Notch signaling, along with a complete overview on the currently available Notch-directed approaches. 相似文献
73.
Acute‐phase response following full‐mouth versus quadrant non‐surgical periodontal treatment: A randomized clinical trial 下载免费PDF全文
74.
Polymorphisms in alcohol and tobacco metabolism genes in head and neck cancer in the Basque Country 下载免费PDF全文
75.
Julia Steinbach Henry Holmstrand Kseniia Shcherbakova Denis Kosmach Volker Brüchert Natalia Shakhova Anatoly Salyuk Clia J. Sapart Denis Chernykh Riko Noormets Igor Semiletov
rjan Gustafsson 《Proceedings of the National Academy of Sciences of the United States of America》2021,118(10)
The East Siberian Arctic Shelf holds large amounts of inundated carbon and methane (CH4). Holocene warming by overlying seawater, recently fortified by anthropogenic warming, has caused thawing of the underlying subsea permafrost. Despite extensive observations of elevated seawater CH4 in the past decades, relative contributions from different subsea compartments such as early diagenesis, subsea permafrost, methane hydrates, and underlying thermogenic/ free gas to these methane releases remain elusive. Dissolved methane concentrations observed in the Laptev Sea ranged from 3 to 1,500 nM (median 151 nM; oversaturation by ∼3,800%). Methane stable isotopic composition showed strong vertical and horizontal gradients with source signatures for two seepage areas of δ13C-CH4 = (−42.6 ± 0.5)/(−55.0 ± 0.5) ‰ and δD-CH4 = (−136.8 ± 8.0)/(−158.1 ± 5.5) ‰, suggesting a thermogenic/natural gas source. Increasingly enriched δ13C-CH4 and δD-CH4 at distance from the seeps indicated methane oxidation. The Δ14C-CH4 signal was strongly depleted (i.e., old) near the seeps (−993 ± 19/−1050 ± 89‰). Hence, all three isotope systems are consistent with methane release from an old, deep, and likely thermogenic pool to the outer Laptev Sea. This knowledge of what subsea sources are contributing to the observed methane release is a prerequisite to predictions on how these emissions will increase over coming decades and centuries.The East Siberian Arctic Shelf (ESAS) is the world’s largest and shallowest shelf sea system, formed through inundation of northeast Siberia during sea level transgression in the early Holocene. The ESAS holds substantial but poorly constrained amounts of organic carbon and methane (CH4). These carbon/methane stores are contained in unknown partitions as gas hydrates, unfrozen sediment, subsea permafrost, gas pockets within and below the subsea permafrost, and as underlying thermogenic gas (1–3). Methane release to the atmosphere from these compartments could potentially have significant effects on the global climate (4, 5), yet there are large uncertainties regarding the size and the vulnerability toward remobilization of these inaccessible and elusive subsea carbon/methane pools. Conceptual development and modeling have predicted that warming of the ESAS system by a combination of geothermal heat and climate-driven Holocene heat flux from overlying seawater, recently further enhanced by Anthropocene warming, may lead to thawing of subsea permafrost (6, 7). Subsea permafrost drilling in the Laptev Sea, in part at the same sites as 30 y ago, has recently confirmed that the subsea permafrost has indeed come near the point of thawing (8). In addition to mobilization of the carbon/methane stored within the subsea permafrost, its degradation can also lead to the formation of pathways for gaseous methane from underlying reservoirs, allowing further methane release to the overlying water column (3, 9).Near-annual ship-based expeditions to the ESAS over the past two decades have documented widespread seep locations with extensive methane releases to the water column (3, 10). Methane levels are often found to be 10 to 100 times higher than the atmospheric equilibrium and are particularly elevated in areas of strong ebullition from subsea gas seeps (“methane hotspots”). Similarly, elevated dissolved methane concentrations in bottom waters appear to be spatially related to the thermal state of subsea permafrost as deduced from modeling results and/or geophysical surveys (7, 9). Currently, we lack critical knowledge on the quantitative or even relative contributions of the different subsea pools to the observed methane release, a prerequisite for robust predictions on how these releases will develop. An important distinction needs to be made between pools that release methane gradually, such as methane produced microbially in shallow sediments during early diagenesis or in thawing subsea permafrost, versus pools with preformed methane that may release more abruptly once pathways are available, such as from disintegrating methane hydrates and pools of thermogenic (natural) gas below the subsea permafrost. Multidimensional isotope analysis offers a useful means to disentangle the relative importance of these different subsea sources of methane to the ESAS: Stable isotope data (δ13C-CH4 and δD-CH4) provide useful information on methane formation and removal pathways, and the radiocarbon content of methane (Δ14C-CH4) helps to determine the age and methane source reservoir (see SI Appendix, text S1 for details on these isotope systematics and typical isotopic signatures for the ESAS subsea system).Here, we present triple-isotope–based source apportionment of methane conducted as part of the Swedish–Russian–US investigation of carbon–climate–cryosphere interactions in the East Siberian Arctic Ocean (SWERUS-C3) program. To this end, the distribution of dissolved methane, its stable carbon and hydrogen isotope composition, as well as natural radiocarbon abundance signature, were investigated with a focus on the isotopic fingerprint of methane escaping the seabed to pinpoint the subsea sources of elevated methane in the outer Laptev Sea. 相似文献
76.
Desirée Gutiérrez-Marín Joaquin Escribano Ricardo Closa-Monasterolo Natalia Ferré Michelle Venables Priya Singh Jonathan C.K. Wells Judit Muñoz-Hernando Marta Zaragoza-Jordana Mariona Gispert-Llauradó Carmen Rubio-Torrents Mireia Alcázar Mercè Núñez-Roig Raquel Monné-Gelonch Albert Feliu Josep Basora Ana M. Alejos Veronica Luque 《Clinical nutrition (Edinburgh, Scotland)》2021,40(3):1102-1107
77.
78.
What Ancestry Can Tell Us About the Genetic Origins of Inter-Ethnic Differences in Asthma Expression
Natalia Hernandez-Pacheco Carlos Flores Sam S. Oh Esteban G. Burchard Maria Pino-Yanes 《Current allergy and asthma reports》2016,16(8):53
Differences in asthma prevalence have been described across different populations, suggesting that genetic ancestry can play an important role in this disease. In fact, several studies have demonstrated an association between African ancestry with increased asthma susceptibility and severity, higher immunoglobulin E levels, and lower lung function. In contrast, Native American ancestry has been shown to have a protective role for this disease. Genome-wide association studies have allowed the identification of population-specific genetic variants with varying allele frequency among populations. Additionally, the correlation of genetic ancestry at the chromosomal level with asthma and related traits by means of admixture mapping has revealed regions of the genome where ancestry is correlated with the disease. In this review, we discuss the evidence supporting the association of genetic ancestry with asthma susceptibility and asthma-related traits, and highlight the regions of the genome harboring ancestry-specific genetic risk factors. 相似文献
79.
Armando Perrotta MD PhD Natalia Arce‐Leal MD PhD Cristina Tassorelli MD PhD Valeria Gasperi PhD Grazia Sances MD Fabio Blandini MD PhD Mariano Serrao MD PhD Monica Bolla MD Francesco Pierelli MD DrMSc Giuseppe Nappi MD DrMSc Mauro Maccarrone DrMSc Giorgio Sandrini MD DrMSc 《Headache》2012,52(9):1350-1361
Objectives.— We investigated (1) a possible relationship between the functional activity of the endocannabinoid system and the facilitation of pain processing in migraineurs with medication‐overuse headache, and (2) the effect of withdrawal treatment on both. Background.— The endocannabinoid system antinociception effect includes prevention of nociceptive pathways sensitization. The sensitization of the pain pathways has been demonstrated to be pivotal in the development and maintenance of chronic form of migraine, including medication‐overuse headache. Methods.— We used the temporal summation threshold of the nociceptive withdrawal reflex to explore the spinal cord pain processing, and the platelet activity of the enzyme fatty acid amide hydrolase to detect the functional state of the endocannabinoid system in 27 medication‐overuse headache subjects before and 10 and 60 days after a standard withdrawal treatment and compared results with those of 14 controls. Results.— A significantly reduced temporal summation threshold and increased related pain sensation was found in subjects before withdrawal treatment when compared with controls. A significant fatty acid amide hydrolase activity reduction coupled with a significant improvement (reduction) in facilitation of spinal cord pain processing (increase in temporal summation threshold and reduction in related pain sensation) was found in medication‐overuse headache subjects at both 10 and 60 days after withdrawal treatment when compared with medication‐overuse headache subjects before withdrawal treatment. Conclusions.— We demonstrated a marked facilitation in spinal cord pain processing in medication‐overuse headache before withdrawal treatment when compared with controls. Furthermore, the acute reduction of the fatty acid amide hydrolase activity coupled with a reduction of the facilitation in pain processing immediately (10 days) after withdrawal treatment and its persistence 60 days after withdrawal treatment could represent the consequence of a mechanism devoted to acutely reduce the degradation of endocannabinoids and aimed to increase the activity of the endocannabinoid system that results in an antinociceptive effect. 相似文献
80.
Han Chung Chong Jeremy Soon Kiat Chan Chi Qin Goh Natalia V Gounko Baiwen Luo Xiaoling Wang Selin Foo Marcus Thien Chong Wong Cleo Choong Sander Kersten Nguan Soon Tan 《Molecular therapy》2014,22(9):1593-1604
Impaired wound healing is a major source of morbidity in diabetic patients. Poor outcome has, in part, been related to increased inflammation, poor angiogenesis, and deficiencies in extracellular matrix components. Despite the enormous impact of these chronic wounds, effective therapies are lacking. Here, we showed that the topical application of recombinant matricellular protein angiopoietin-like 4 (ANGPTL4) accelerated wound reepithelialization in diabetic mice, in part, by improving angiogenesis. ANGPTL4 expression is markedly elevated upon normal wound injury. In contrast, ANGPTL4 expression remains low throughout the healing period in diabetic wounds. Exogenous ANGPTL4 modulated several regulatory networks involved in cell migration, angiogenesis, and inflammation, as evidenced by an altered gene expression signature. ANGPTL4 influenced the expression profile of endothelial-specific CD31 in diabetic wounds, returning its profile to that observed in wild-type wounds. We showed ANGPTL4-induced nitric oxide production through an integrin/JAK/STAT3-mediated upregulation of inducible nitric oxide synthase (iNOS) expression in wound epithelia, thus revealing a hitherto unknown mechanism by which ANGPTL4 regulated angiogenesis via keratinocyte-to-endothelial-cell communication. These data show that the replacement of ANGPTL4 may be an effective adjunctive or new therapeutic avenue for treating poor healing wounds. The present finding also confirms that therapeutic angiogenesis remains an attractive treatment modality for diabetic wound healing. 相似文献