全文获取类型
收费全文 | 9809篇 |
免费 | 928篇 |
国内免费 | 3篇 |
出版年
2023年 | 79篇 |
2022年 | 159篇 |
2021年 | 340篇 |
2020年 | 198篇 |
2019年 | 267篇 |
2018年 | 229篇 |
2017年 | 229篇 |
2016年 | 376篇 |
2015年 | 668篇 |
2014年 | 737篇 |
2013年 | 774篇 |
2012年 | 994篇 |
2011年 | 869篇 |
2010年 | 528篇 |
2009年 | 451篇 |
2008年 | 565篇 |
2007年 | 536篇 |
2006年 | 469篇 |
2005年 | 399篇 |
2004年 | 370篇 |
2003年 | 284篇 |
2002年 | 266篇 |
2001年 | 59篇 |
2000年 | 39篇 |
1999年 | 57篇 |
1998年 | 52篇 |
1997年 | 40篇 |
1996年 | 33篇 |
1995年 | 28篇 |
1994年 | 30篇 |
1993年 | 25篇 |
1992年 | 27篇 |
1991年 | 25篇 |
1990年 | 23篇 |
1989年 | 33篇 |
1988年 | 21篇 |
1987年 | 17篇 |
1986年 | 15篇 |
1985年 | 25篇 |
1984年 | 30篇 |
1983年 | 21篇 |
1982年 | 19篇 |
1981年 | 23篇 |
1980年 | 21篇 |
1979年 | 16篇 |
1978年 | 17篇 |
1977年 | 15篇 |
1976年 | 22篇 |
1974年 | 15篇 |
1971年 | 13篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
71.
David Julian Arias-Chávez Patrick Mailloux-Salinas Jessica Ledesma Aparicio Elihu Campos-Pérez Omar Noel Medina-Campos José Pedraza-Chaverri Guadalupe Bravo 《Journal of cellular and molecular medicine》2023,27(20):3147-3156
Benign prostatic hyperplasia (BPH) is the most common adenoma in old men. Tomatoes are a rich source of bioactive compounds that, as well as selenium (Se), possess antioxidant and antiproliferative activity. The aim was to evaluate the therapeutic effect of Se in combination with a tomato extract in aged rats with BPH. Aged male Wistar rats were divided in the following groups (n = 10 rats/group): Control (C), BPH, BPH + Finasteride (BPH + F), BPH + Tomato Lipidic Extract (BPH + E), BPH + Selenium (BPH + S) and BPH plus E plus S (BPH + E + S). After 4 weeks of treatment, prostate weight, diuresis, antioxidants enzymes, prooxidants and inflammatory markers, growth factors and androgens were determined. BPH + E + S reduced prostate weight by 59.29% and inhibited growth by 99.35% compared to BPH + F which only decreased weight and inhibited growth by 15.31% and 57.54%, respectively. Prooxidant markers were higher with BPH + F (49.4% higher vs. BPH), but BPH + E + S decreased these markers (94.27% vs. BPH) and increased antioxidant activity. Finally, diuresis was higher with the BPH + E + S combination and markers of inflammation and growth factors were significantly lower with respect to BPH + F. Our findings provide a beneficial and protective therapeutic option of E + S directed against androgens, oxidative stress and inflammation that regulates cell proliferation in the prostate gland. 相似文献
72.
Francesca Vittoria Sbrana Benedetta Fiordi Jessica Bordini Daniela Belloni Federica Barbaglio Luca Russo Lydia Scarfò Paolo Ghia Cristina Scielzo 《Journal of cellular and molecular medicine》2023,27(4):576-586
Chronic Lymphocytic Leukaemia (CLL) is the most common adult B-cell leukaemia and despite improvement in patients' outcome, following the use of targeted therapies, it remains incurable. CLL supportive microenvironment plays a key role in both CLL progression and drug resistance through signals that can be sensed by the main components of the focal adhesion complex, such as FAK and PYK2 kinases. Dysregulations of both kinases have been observed in several metastatic cancers, but their role in haematological malignancies is still poorly defined. We characterized FAK and PYK2 expression and observed that PYK2 expression is higher in leukaemic B cells and its overexpression significantly correlates with their malignant transformation. When targeting both FAK and PYK2 with the specific inhibitor defactinib, we observed a dose–response effect on CLL cells viability and survival. In vivo treatment of a CLL mouse model showed a decrease of the leukaemic clone in all the lymphoid organs along with a significant reduction of macrophages and of the spleen weight and size. Our results first define a possible prognostic value for PYK2 in CLL, and show that both FAK and PYK2 might become putative targets for both CLL and its microenvironment (e.g. macrophages), thus paving the way to an innovative therapeutic strategy. 相似文献
73.
Matteo Zurlo Francesco Nicoli Davide Proietto Beatrice Dallan Cristina Zuccato Lucia Carmela Cosenza Jessica Gasparello Chiara Papi Elisabetta d'Aversa Monica Borgatti Chiara Scapoli Alessia Finotti Roberto Gambari 《Journal of cellular and molecular medicine》2023,27(3):353-364
Inhibitors of the mammalian target of rapamycin (mTOR) have been proposed to improve vaccine responses, especially in the elderly. Accordingly, testing mTOR inhibitors (such as Sirolimus) and other geroprotective drugs might be considered a key strategy to improve overall health resilience of aged populations. In this respect, Sirolimus (also known as rapamycin) is of great interest, in consideration of the fact that it is extensively used in routine therapy and in clinical studies for the treatment of several diseases. Recently, Sirolimus has been considered in laboratory and clinical studies aimed to find novel protocols for the therapy of hemoglobinopathies (e.g. β-Thalassemia). The objective of the present study was to analyse the activity of CD4+ and CD8+ T cells in β-Thalassemia patients treated with Sirolimus, taking advantages from the availability of cellular samples of the NCT03877809 clinical trial. The approach was to verify IFN-γ releases following stimulation of peripheral blood mononuclear cells (PBMCs) to stimulatory CEF and CEFTA peptide pools, stimulatory for CD4+ and CD8+ T cells, respectively. The main results of the present study are that treatment of β-Thalassemia patients with Sirolimus has a positive impact on the biological activity and number of memory CD4+ and CD8+ T cells releasing IFN-γ following stimulation with antigenic stimuli present in immunological memory. These data are to our knowledge novel and in our opinion of interest, in consideration of the fact that β-Thalassemia patients are considered prone to immune deficiency. 相似文献
74.
Differential expression of two related amino acid transporters with differing substrate specificity in Arabidopsis thaliana 总被引:8,自引:3,他引:5
Marion Kwart Brigitte Hirner Sabine Hummel Wolf B. Frommer 《The Plant journal : for cell and molecular biology》1993,4(6):993-1002
A general amino acid permease cDNA ( AAP2 ) was isolated from Arabidopsis by complementation of a yeast mutant defective in citrulline uptake. Direct transport measurements in yeast show that the protein mediates uptake of l -[14 C]-citrulline and l -[14 C]-proline. Detailed analyses of the substrate specificity by competition studies demonstrate that all proteogenic amino acids are recognized by the carrier, including those that represent the major transport forms of reduced nitrogen in many species, i.e. glutamine, glutamate and asparagine. Thus, AAP2 is less selective as compared with AAP1 and transports basic amino acids such as histidine as shown by expression in a histidine transport-deficient yeast strain. The predicted polypeptide of 53 kDa is highly hydrophobic with 12 putative membrane-spanning regions and shows significant homologies to the Arabidopsis broad specificity permease AAP1, and a limited homology to bacterial branched chain amino acid transporters, but not to any other known proteins. Alterations in the charged residues as compared with AAP1 in four regions might be involved in the difference in selectivity towards basic amino acids. Both genes are highly expressed in developing pods indicating a role in supplying the developing seeds with reduced nitrogen. AAP2 is selectively expressed in the stem and might therefore play a role in xylem-to-phloem transfer of amino acids during seed filling. Furthermore in situ hybridization shows that both genes are expressed in the vascular system of cotyledons in developing seedlings. 相似文献
75.
Many tropical animals inhabit mosaic landscapes including human-modified habitat. In such landscapes, animals commonly adjust feeding behavior, and may incorporate non-natural foods. These behavioral shifts can influence consumers' nutritional states, with implications for population persistence. However, few studies have addressed the nutritional role of non-natural food. We examined nutritional ecology of wild blue monkeys to understand how dietary habits related to non-natural foods might support population persistence in a mosaic landscape. We documented prevalence and nutritional composition of non-natural foods in monkey diets to assess how habitat use influenced their consumption, and their contribution to nutritional strategies. While most energy and macronutrients came from natural foods, subjects focused non-natural feeding activity on five exotic plants, and averaged about a third of daily calories from non-natural foods. Most non-natural food calories came from non-structural carbohydrates and least from protein. Consumption of non-natural foods related to time in human-modified habitats, which two groups used non-randomly. Non-natural and natural foods were similar in nutrients, and the amount of non-natural food consumed drove variation in nutritional strategy. When more daily calories came from non-natural foods, females consumed a higher ratio of non-protein energy to protein (NPE:P). Females also prioritized protein while allowing NPE:P to vary, increasing NPE while capitalizing on non-natural foods. Overall, these tropical mammals achieved a similar nutrient balance regardless of their intake of non-natural foods. Forest and forest-adjacent areas with non-natural vegetation may provide adequate nutrient access for consumers, and thus contribute to wildlife conservation in mosaic tropical landscapes. 相似文献
76.
To investigate the role of proline in defining β turn conformations within cyclic hexa- and pentapeptides we synthesized and determined the conformations of a series of L - and D -proline-containing peptides by means of 2D NMR spectroscopy and restrained molecular dynamics simulations. Due to cis/trans isomerism the L -proline peptides adopt at least two different conformations that are analyzed and compared to the structures of the corresponding D -proline peptides. The cis conformations of the compounds cyclo(-Pro-Ala-Ala-Pro-Ala-Ala-), cyclo(-Arg-Gly-Asp-Phe-Pro-Gly-), cyclo(-Arg-Gly-Asp-Phe-Pro-Ala-), cyclo(-Pro-Ala-Ala-Ala-Ala--), and cyclo(-Pro-Ala-Pro-Ala-Ala-) form uncommon βVI turns that mimic the turn geometries found in crystallographically refined protein structures at such a detailed level that even preferred side chain orientations are reproduced. The ratios of the cis/trans isomers are analyzed in terms of the steric demand of the proline-following residue. The conformational details derived from this study illustrate the importance of the examination of small model compounds derived from protein loop regions, especially if bioactive recognition sequences, such as RGD (Arg-Gly-Asp), are incorporated. © 1993 Wiley-Liss, Inc. 相似文献
77.
Arpana Agrawal Sarah J. Brislin Kathleen K. Bucholz Danielle Dick Ronald P. Hart Emma C. Johnson Jacquelyn Meyers Jessica Salvatore Paul Slesinger COGA Collaborators Laura Almasy Tatiana Foroud Alison Goate Victor Hesselbrock John Kramer Samuel Kuperman Alison K. Merikangas John I. Nurnberger Jay Tischfield Howard J. Edenberg Bernice Porjesz 《Genes, Brain & Behavior》2023,22(5):e12864
78.
João Ricardo Sato Claudinei Eduardo Biazoli Ana Paula Arantes Bueno Arthur Caye Pedro Mario Pan Marcos Santoro Jessica Honorato-Mauer Giovanni Abrahão Salum Marcelo Queiroz Hoexter Rodrigo Affonseca Bressan Andrea Parolin Jackowski Euripedes Constantino Miguel Sintia Belangero Luis Augusto Rohde 《Genes, Brain & Behavior》2023,22(2):e12838
79.
Dr. Sufi Desrini Julien Ducloux Guillaume Hamion Prof. Charles Bodet Dr. Jérome Labanowski Prof. Mustofa Mustofa Prof. Titik Nuryastuti Prof. Christine Imbert Dr. Marion Girardot 《化学与生物多样性》2023,20(8):e202300130
The extracts of five invasive plants were investigated for antifungal and antibiofilm activities against Candida albicans, C. glabrata, C. krusei, and C. parapsilosis. The antifungal activity was evaluated using the microdilution assay and the antibiofilm effect by measurement of the metabolic activity. Ethanol and ethanol-water extracts of Reynoutria japonica leaves inhibited 50 % of planktonic cells at 250 μg mL−1 and 15.6 μg mL−1, respectively. Ethanol and ethanol-water extracts of Baccharis halimifolia inhibited >75 % of the mature biofilm of C. albicans at 500 μg mL−1. The essential oil (EO) of B. halimifolia leaves was the most active (50 % inhibition (IC50) at 4 and 74 μg mL−1against the maturation phase and 24 h old-biofilms of C. albicans, respectively). Oxygenated sesquiterpenes were the primary contents in this EO (62.02 %), with β-caryophyllene oxide as the major component (37 %). Aromadendrene oxide-(2), β-caryophyllene oxide, and (±)-β-pinene displayed significant activities against the maturation phase (IC50=9–310 μ mol l−1) and preformed 24 h-biofilm (IC50=38–630 μ mol l−1) of C. albicans with very low cytotoxicity for the first two compounds. C. albicans remained the most susceptible species to this EO and its components. This study highlighted for the first time the antibiofilm potential of B. halimifolia, its EO and some of its components. 相似文献
80.
Marion E. Garaï 《Ethology : formerly Zeitschrift fur Tierpsychologie》1992,90(3):187-205
Social relationships between female zoo elephants were analyzed on three different zoo groups. Interactions were defined as either affiliative or agonistic. The most frequent interactions were found to be touching of the partner's mouth, genital sinus, face and trunk. The calf was the individual involved in most social interactions. Placing the trunk tip into the partner's mouth is a well known behaviour, the correlation between this behaviour and aggression was analyzed and a further function is suggested. Aggressive behaviour was analyzed and the hypothesis derived that rank order has to be established and is flexible in a non-kin group. The hypothesis that Asian elephant females may form special relationships was tested and confirmed. The following behaviour patterns were determined as indicators of a special relationship: Spatial proximity, partner-specific reactions to arousal and to vocalizing, and omission of agonistic behaviour. An experiment confirmed the hypothesis that the removal of one member of a special relationship from the enclosure would elicit more arousal behaviour in the respective partner. 相似文献