全文获取类型
收费全文 | 2319648篇 |
免费 | 178000篇 |
国内免费 | 3675篇 |
专业分类
耳鼻咽喉 | 32018篇 |
儿科学 | 71613篇 |
妇产科学 | 64111篇 |
基础医学 | 329563篇 |
口腔科学 | 70086篇 |
临床医学 | 203798篇 |
内科学 | 451668篇 |
皮肤病学 | 49253篇 |
神经病学 | 184885篇 |
特种医学 | 92300篇 |
外国民族医学 | 541篇 |
外科学 | 360451篇 |
综合类 | 53785篇 |
现状与发展 | 3篇 |
一般理论 | 754篇 |
预防医学 | 171352篇 |
眼科学 | 53502篇 |
药学 | 177282篇 |
6篇 | |
中国医学 | 4705篇 |
肿瘤学 | 129647篇 |
出版年
2018年 | 21537篇 |
2016年 | 18746篇 |
2015年 | 21649篇 |
2014年 | 29794篇 |
2013年 | 44924篇 |
2012年 | 61052篇 |
2011年 | 64180篇 |
2010年 | 37915篇 |
2009年 | 36309篇 |
2008年 | 61915篇 |
2007年 | 65266篇 |
2006年 | 66504篇 |
2005年 | 64552篇 |
2004年 | 63251篇 |
2003年 | 60594篇 |
2002年 | 59392篇 |
2001年 | 115775篇 |
2000年 | 120012篇 |
1999年 | 101309篇 |
1998年 | 26079篇 |
1997年 | 23546篇 |
1996年 | 23522篇 |
1995年 | 22635篇 |
1994年 | 21130篇 |
1993年 | 19798篇 |
1992年 | 81808篇 |
1991年 | 79131篇 |
1990年 | 77079篇 |
1989年 | 74802篇 |
1988年 | 69025篇 |
1987年 | 67844篇 |
1986年 | 64157篇 |
1985年 | 61982篇 |
1984年 | 45493篇 |
1983年 | 39048篇 |
1982年 | 22079篇 |
1981年 | 19602篇 |
1980年 | 18250篇 |
1979年 | 42571篇 |
1978年 | 29158篇 |
1977年 | 24799篇 |
1976年 | 22779篇 |
1975年 | 24453篇 |
1974年 | 29753篇 |
1973年 | 28524篇 |
1972年 | 26480篇 |
1971年 | 24956篇 |
1970年 | 23275篇 |
1969年 | 21864篇 |
1968年 | 19930篇 |
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
21.
Katja T. Turunen Vasiliki Pletsa Panagiotis Georgiadis John K. Triantafillidis Dimitrios Karamanolis 《Nutrition and cancer》2016,68(4):560-567
The aim of the study was to determine the effect of β-glucan on the cytotoxicity and genotoxicity of polypectomized patient's fecal water (FW). Polypectomized volunteers (n = 69) were randomly assigned to consume bread with or without β-glucan, for 3 months. FW was collected at the beginning (t = 0), the 30th and 90th day and 2 wk after the intervention. Cytotoxicity and genotoxicity were estimated on Caco-2 cells, using trypan blue exclusion test and comet assay, respectively. Gastrointestinal symptoms were recorded and subjects kept a 3-day food diary at baseline and after completion. Trypan blue exclusion test revealed cell survival of approximately 87% after incubation with FW. The FW samples showed 49% genotoxicity at the baseline. Genotoxicity in the intervention group decreased during the trial reaching statistical significance on the 90th day compared to control. An increase was noticed 2 wk after the trial, but it still remained significantly lower compared to control. Group-specific analysis for β-glucan also revealed significant decrease in the genotoxicity on the 90th day compared to baseline. β-glucan ingestion in polypectomized patients significantly decreased the genotoxicity of their FW. Our findings suggest that β-glucan consumption could possibly provide protection against colon cancer development. 相似文献
22.
23.
Rishad R. Jivani Gaurang J. Lakhtaria Dhaval D. Patadiya Laxman D. Patel Nurrudin P. Jivani Bhagyesh P. Jhala 《Saudi Pharmaceutical Journal》2016,24(1):1-20
Advancement in microelectromechanical system has facilitated the microfabrication of polymeric substrates and the development of the novel class of controlled drug delivery devices. These vehicles have specifically tailored three dimensional physical and chemical features which together, provide the capacity to target cell, stimulate unidirectional controlled release of therapeutics and augment permeation across the barriers. Apart from drug delivery devices microfabrication technology’s offer exciting prospects to generate biomimetic gastrointestinal tract models. BioMEMS are capable of analysing biochemical liquid sample like solution of metabolites, macromolecules, proteins, nucleic acid, cells and viruses. This review summarized multidisciplinary application of biomedical microelectromechanical systems in drug delivery and its potential in analytical procedures. 相似文献
24.
Dalton Luiz Schiessel Ricardo K. Yamazaki Marcelo Kryczyk Isabela Coelho de Castro Adriana A. Yamaguchi Danielle C. T. Pequito 《Nutrition and cancer》2016,68(8):1369-1380
Objective: Polyunsaturated fatty acids n-3 (PUFA n-3) have shown effects in reducing tumor growth, in particular eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) abundantly present in fish oil (FO). When these fatty acids are provided in the diet, they alter the functions of the cells, particularly in tumor and immune cells. However, the effects of α-linolenic fatty acid (ALA), which is the precursor of EPA and DHA, are controversial. Thus, our objective was to test the effect of this parental fatty acid. Methods: Non-tumor-bearing and tumor-bearing Wistar rats (70 days) were supplemented with 1 g/kg body weight of FO or Oro Inca® (OI) oil (rich in ALA). Immune cells function, proliferation, cytokine production, and subpopulation profile were evaluated. Results: We have shown that innate immune cells enhanced phagocytosis capacity, and increased processing and elimination of antigens. Moreover, there was a decrease in production of pro-inflammatory cytokines (tumor necrosis factor-alpha (TNF-α) and interleukin 6 (IL-6)) by macrophages. Lymphocytes showed decreased proliferation capacity, increased cluster of differentiation 8 (CD8+) subpopulation, and increased TNF-α production. Conclusions: Oil rich in ALA caused similar immune modulation in cancer when compared with FO. 相似文献
25.
M. R. D. Maslin S. K. Lloyd S. Rutherford S. Freeman A. King D. R. Moore K. J. Munro 《Journal of the Association for Research in Otolaryngology》2015,16(5):631-640
Individuals with sudden unilateral deafness offer a unique opportunity to study plasticity of the binaural auditory system in adult humans. Stimulation of the intact ear results in increased activity in the auditory cortex. However, there are no reports of changes at sub-cortical levels in humans. Therefore, the aim of the present study was to investigate changes in sub-cortical activity immediately before and after the onset of surgically induced unilateral deafness in adult humans. Click-evoked auditory brainstem responses (ABRs) to stimulation of the healthy ear were recorded from ten adults during the course of translabyrinthine surgery for the removal of a unilateral acoustic neuroma. This surgical technique always results in abrupt deafferentation of the affected ear. The results revealed a rapid (within minutes) reduction in latency of wave V (mean pre = 6.55 ms; mean post = 6.15 ms; p < 0.001). A latency reduction was also observed for wave III (mean pre = 4.40 ms; mean post = 4.13 ms; p < 0.001). These reductions in response latency are consistent with functional changes including disinhibition or/and more rapid intra-cellular signalling affecting binaurally sensitive neurons in the central auditory system. The results are highly relevant for improved understanding of putative physiological mechanisms underlying perceptual disorders such as tinnitus and hyperacusis. 相似文献
26.
Xiaoyan Lu Isabelle R. Miousse Sandra V. Pirela Jodene K. Moore Stepan Melnyk 《Nanotoxicology》2016,10(5):629-639
Evidence continues to grow on potential environmental health hazards associated with engineered nanomaterials (ENMs). While the geno- and cytotoxic effects of ENMs have been investigated, their potential to target the epigenome remains largely unknown. The aim of this study is two-fold: 1) determining whether or not industry relevant ENMs can affect the epigenome in vivo and 2) validating a recently developed in vitro epigenetic screening platform for inhaled ENMs. Laser printer-emitted engineered nanoparticles (PEPs) released from nano-enabled toners during consumer use and copper oxide (CuO) were chosen since these particles induced significant epigenetic changes in a recent in vitro companion study. In this study, the epigenetic alterations in lung tissue, alveolar macrophages and peripheral blood from intratracheally instilled mice were evaluated. The methylation of global DNA and transposable elements (TEs), the expression of the DNA methylation machinery and TEs, in addition to general toxicological effects in the lung were assessed. CuO exhibited higher cell-damaging potential to the lung, while PEPs showed a greater ability to target the epigenome. Alterations in the methylation status of global DNA and TEs, and expression of TEs and DNA machinery in mouse lung were observed after exposure to CuO and PEPs. Additionally, epigenetic changes were detected in the peripheral blood after PEPs exposure. Altogether, CuO and PEPs can induce epigenetic alterations in a mouse experimental model, which in turn confirms that the recently developed in vitro epigenetic platform using macrophage and epithelial cell lines can be successfully utilized in the epigenetic screening of ENMs. 相似文献
27.
28.
29.
F. Fruzzetti G. Palla A. Sbrana T. Simoncini M. R. Sessa 《Gynecological endocrinology》2020,36(10):938-940
AbstractObjective: To understand the origin of extremely high gonadotropin levels in a perimenopausal woman.Methods: A 52-year-old woman with a 2?months of amenorrhea followed spontaneous menstrual cycles recovery was referred to our outpatient clinic with elevated follicle-stimulating hormone (FSH, 483 mUI/ml), luteinizing hormone (LH, 475 mUI/ml) and prolactin (PRL, 173?ng/ml). She was known to take levosulpiride. The gonadotropin levels did not fit with the clinical features.Results: A gonadotroph tumor was ruled out. Further analysis confirmed constantly high FSH, LH and PRL levels. The measurements were repeated using different analytical platforms with different results. After serial dilutions, nonlinearity was present suggesting an immunoassay interference. After post-polyethylene glycol recovery, hormone levels appeared in the normal range. Anti-goat antibodies were recognized in the serum of the patient.Conclusions: This case report shows a case of falsely abnormal high gonadotropin and PRL levels in a woman during menopause transition. In the clinical practice the evaluation of gonadotropin profile is not recommended at this age, but the abnormal levels stimulated further evaluation. An interference in the assay due to anti-goat antibodies resulted in abnormally high level of FSH and LH. A strict collaboration between clinicians and the laboratory is needed, when laboratory findings do not correspond to clinical findings. 相似文献
30.
T. Wu L. G. Trahair M. J. Bound C. F. Deacon M. Horowitz C. K. Rayner K. L. Jones 《Diabetic medicine》2015,32(5):595-600