全文获取类型
收费全文 | 2646篇 |
免费 | 116篇 |
国内免费 | 1篇 |
出版年
2023年 | 8篇 |
2022年 | 37篇 |
2021年 | 66篇 |
2020年 | 40篇 |
2019年 | 41篇 |
2018年 | 58篇 |
2017年 | 57篇 |
2016年 | 81篇 |
2015年 | 99篇 |
2014年 | 142篇 |
2013年 | 189篇 |
2012年 | 227篇 |
2011年 | 211篇 |
2010年 | 120篇 |
2009年 | 102篇 |
2008年 | 140篇 |
2007年 | 144篇 |
2006年 | 151篇 |
2005年 | 115篇 |
2004年 | 104篇 |
2003年 | 113篇 |
2002年 | 95篇 |
2001年 | 23篇 |
2000年 | 26篇 |
1999年 | 20篇 |
1998年 | 32篇 |
1997年 | 16篇 |
1996年 | 9篇 |
1995年 | 19篇 |
1994年 | 14篇 |
1993年 | 17篇 |
1992年 | 16篇 |
1991年 | 17篇 |
1990年 | 9篇 |
1989年 | 10篇 |
1988年 | 16篇 |
1987年 | 15篇 |
1986年 | 7篇 |
1985年 | 11篇 |
1984年 | 17篇 |
1983年 | 9篇 |
1982年 | 14篇 |
1981年 | 9篇 |
1980年 | 10篇 |
1979年 | 8篇 |
1978年 | 8篇 |
1976年 | 7篇 |
1973年 | 7篇 |
1972年 | 6篇 |
1970年 | 6篇 |
排序方式: 共有2763条查询结果,搜索用时 218 毫秒
81.
82.
Gitanjali Tandon Sarika Jaiswal M.A. Iquebal Sunil Kumar Sukhdeep Kaur Anil Rai 《Journal of biomolecular structure & dynamics》2013,31(10):2180-2191
Biotic stress is a major cause of heavy loss in grape productivity. In order to develop biotic stress-resistant grape varieties, the key defense genes along with its pathway have to be deciphered. In angiosperm plants, lipase-like protein phytoalexin deficient 4 (PAD4) is well known to be essential for systemic resistance against biotic stress. PAD4 functions together with its interacting partner protein enhanced disease susceptibility 1 (EDS1) to promote salicylic acid (SA)-dependent and SA-independent defense pathway. Existence and structure of key protein of systemic resistance EDS1 and PAD4 are not known in grapes. Before SA pathway studies are taken in grape, molecular evidence of EDS1: PAD4 complex is to be established. To establish this, EDS1 protein sequence was retrieved from NCBI and homologous PAD4 protein was generated using Arabidopsis thaliana as template and conserved domains were confirmed. In this study, computational methods were used to model EDS1 and PAD4 and simulated the interactions of EDS1 and PAD4. Since no structural details of the proteins were available, homology modeling was employed to construct three-dimensional structures. Further, molecular dynamic simulations were performed to study the dynamic behavior of the EDS1 and PAD4. The modeled proteins were validated and subjected to molecular docking analysis. Molecular evidence of stable complex of EDS1:PAD4 in grape supporting SA defense pathway in response to biotic stress is reported in this study. If SA defense pathway genes are explored, then markers of genes involved can play pivotal role in grape variety development especially against biotic stress leading to higher productivity. 相似文献
83.
Sini Thomas Anjali Anand Viswanthan Chinnusamy Anil Dahuja Sudipta Basu 《Acta Physiologiae Plantarum》2013,35(12):3401-3411
Chickpea seeds of Pusa 1053 (Mediterranean) and Pusa 256 (native) were magnetoprimed with 100 mT static magnetic field for 1 h to evaluate the effect of magnetopriming on germination of seeds under saline conditions. Enhanced rate of germination and seedling growth parameters (root and shoot length, and vigour indices) under different salinity levels indicated that magnetopriming was more effective in alleviating salinity stress at early seedling stage in Pusa 1053 as compared to Pusa 256. Dynamics of seed water absorption in magnetoprimed seeds showed increased water uptake in Pusa 1053 under non-saline as compared to saline conditions. This could have resulted in faster hydration of enzymes in primed seeds leading to higher rate of germination. Total amylase, protease and dehydrogenase activities were higher in primed seeds as compared to unprimed seeds under both non-saline and saline conditions. Production of superoxide radicals was enhanced in germinating seeds of both the genotypes under salinity irrespective of priming. Increased levels of hydrogen peroxide in germinating magnetoprimed seeds, under both the growing conditions, suggested its role in promotion of germination. Our results showed that magnetopriming of dry seeds of chickpea can be effectively used as a pre-sowing treatment for mitigating adverse effects of salinity at seed germination and early seedling growth. 相似文献
84.
Alison M. Strack Ester Carballo-Jane Sheng-ping Wang Jiyan Xue Xiaoli Ping Lesley Ann McNamara Anil Thankappan Olga Price Michael Wolff T. J. Wu Douglas Kawka Michele Mariano Charlotte Burton Ching H. Chang Jing Chen John Menke Silvi Luell Emanuel I. Zycband Xinchun Tong Richard Raubertas Carl P. Sparrow Brian Hubbard John Woods Gary O'Neill M. Gerard Waters Ayesha Sitlani 《Journal of lipid research》2013,54(1):177-188
The use of nicotinic acid to treat dyslipidemia is limited by induction of a “flushing” response, mediated in part by the interaction of prostaglandin D2 (PGD2) with its G-protein coupled receptor, DP1 (Ptgdr). The impact of DP1 blockade (genetic or pharmacologic) was assessed in experimental murine models of atherosclerosis. In Ptgdr−/−ApoE−/− mice versus ApoE−/− mice, both fed a high-fat diet, aortic cholesterol content was modestly higher (1.3- to 1.5-fold, P < 0.05) in Ptgdr−/−ApoE−/− mice at 16 and 24 weeks of age, but not at 32 weeks. In multiple ApoE−/− mouse studies, a DP1-specific antagonist, L-655, generally had a neutral to beneficial effect on aortic lipids in the presence or absence of nicotinic acid treatment. In a separate study, a modest increase in some atherosclerotic measures was observed with L-655 treatment in Ldlr−/− mice fed a high-fat diet for 8 weeks; however, this effect was not sustained for 16 or 24 weeks. In the same study, treatment with nicotinic acid alone generally decreased plasma and/or aortic lipids, and addition of L-655 did not negate those beneficial effects. These studies demonstrate that inhibition of DP1, with or without nicotinic acid treatment, does not lead to consistent or sustained effects on plaque burden in mouse atherosclerotic models. 相似文献
85.
Nupur Bhumika Vaidya Naga Radha Srinivas Tanuku Anil Kumar Pinnaka 《Antonie van Leeuwenhoek》2013,103(2):347-355
A novel marine, Gram-negative, rod-shaped bacterium, designated strain N9T, was isolated from a water sample of the sea shore at Visakhapatnam, Andhra Pradesh (India). Strain N9T was found to be positive for oxidase and catalase activities. The fatty acids were found to be dominated by C16:0, C18:1 ω7c and summed in feature 3 (C16:1 ω7c and/or C16:1 ω6c). Strain N9T was determined to contain Q-10 as the major respiratory quinone and phosphatidylethanolamine, phosphatidylglycerol, two aminophospholipids, two phospholipids and four unidentified lipids as polar lipids. The DNA G+C content of the strain N9T was found to be 63 mol%. 16S rRNA gene sequence analysis indicated that Rhodobacter sphaeroides, Rhodobacter johrii, Pseudorhodobacter ferrugineus, Rhodobacter azotoformans, Rhodobacter ovatus and Pseudorhodobacter aquimaris were the nearest phylogenetic neighbours, with pair-wise sequence similarities of 95.43, 95.36, 94.24, 95.31, 95.60 and 94.74 %, respectively. Phylogenetic analysis showed that strain N9T formed a distinct branch within the family Rhodobacteraceae and clustered with the clade comprising species of the genus Pseudorhodobacter, together with species of the genera Roseicitreum, Roseinatronobacter, Roseibaca and Rhodobaca. Species of the genus Pseudorhodobacter are phylogenetically close with a 16S rRNA gene sequence dissimilarity of 5.9–7.3 % (92.7–94.1 % similarity). Based on the above-mentioned phenotypic characteristics and on phylogenetic inference, strain N9T is proposed as a representative of a new genus and a novel species of the family Rhodobacteraceae as Albirhodobacter marinus gen. nov., sp. nov. The type strain of Albirhodobacter marinus is N9 (= MTCC 11277T = JCM 17680T). 相似文献
86.
87.
Chiranjeevi Tikka Hari Prasad Osuru Navya Atluri Praveen Chakravarthi Veera Raghavulu Nanda Kumar yellapu Ismail Shaik Mannur Uppu Venkateswara Prasad Sudheer Aluru Narasimha Varma K Matcha Bhaskar 《Bioinformation》2013,9(8):421-425
Yeast strains are commonly associated with sugar rich environments. Various fruit samples were selected as source for isolating
yeast cells. The isolated cultures were identified at Genus level by colony morphology, biochemical characteristics and cell
morphological characters. An attempt has been made to check the viability of yeast cells under different concentrations of ethanol.
Ethanol tolerance of each strain was studied by allowing the yeast to grow in liquid YEPD (Yeast Extract Peptone Dextrose)
medium having different concentrations of ethanol. A total of fifteen yeast strains isolated from different samples were used for the
study. Seven strains of Saccharomyces cerevisiae obtained from different fruit sources were screened for ethanol tolerance. The
results obtained in this study show a range of tolerance levels between 7%-12% in all the stains. Further, the cluster analysis based
on 22 RAPD (Random Amplified polymorphic DNA) bands revealed polymorphisms in these seven Saccharomyces strains. 相似文献
88.
Anna Nolan Elaine Fajardo Maryann L. Huie Rany Condos Anil Pooran Rodney Dawson Keertan Dheda Eric Bateman William N. Rom Michael D. Weiden 《PloS one》2013,8(3)
Background
Tuberculosis (TB) causes 1.45 million deaths annually world wide, the majority of which occur in the developing world. Active TB disease represents immune failure to control latent infection from airborne spread. Acid-fast bacillus (AFB) seen on sputum smear is a biomarker for contagiousness.Methods
We enrolled 73 tuberculosis patients with extensive infiltrates into a research study using bronchoalveolar lavage (BAL) to sample lung immune cells and assay BAL cell cytokine production. All patients had sputum culture demonstrating Mycobacterium tuberculosis and 59/73 (81%) had AFB identified by microscopy of the sputum. Compared with smear negative patients, smear positive patients at presentation had a higher proportion with smoking history, a higher proportion with temperature >38.50 C, higher BAL cells/ml, lower percent lymphocytes in BAL, higher IL-4 and IL-12p40 in BAL cell supernatants. There was no correlation between AFB smear and other BAL or serum cytokines. Increasing IL-4 was associated with BAL PMN and negatively associated with BAL lymphocytes. Each 10-fold increase in BAL IL-4 and IL-12p40 increased the odds of AFB smear positivity by 7.4 and 2.2-fold, respectively, in a multi-variable logistic model.Conclusion
Increasing IL-4 and IL-12p40 production by BAL cells are biomarkers for AFB in sputum of patients who present with radiographically advanced TB. They likely reflect less effective immune control of pathways for controlling TB, leading to patients with increased infectiousness. 相似文献89.
Rong Jin Shiyong Yu Zifang Song Xiaolei Zhu Cuiping Wang Jinchuan Yan Fusheng Wu Anil Nanda D. Neil Granger Guohong Li 《PloS one》2013,8(6)
Recent work has revealed an essential involvement of soluble CD40L (sCD40L) in inflammation and vascular disease. Activated platelets are the major source of sCD40L, which has been implicated in platelet and leukocyte activation, although its exact functional impact on leukocyte-platelet interactions and the underlying mechanisms remain undefined. We aimed to determine the impact and the mechanisms of sCD40L on neutrophils. We studied neutrophil interactions with activated, surface-adherent platelets as a model for leukocyte recruitment to the sites of injury. Our data show that CD40L contributes to neutrophil firm adhesion to and transmigration across activated surface-adherent platelets, possibly through two potential mechanisms. One involves the direct interaction of ligand-receptor (CD40L-CD40), i.e., platelet surface CD40L interaction with neutrophil CD40; another involves an indirect mechanism, i.e. soluble CD40L stimulates activation of the leukocyte-specific β2 integrin Mac-1 in neutrophils and thereby further promotes neutrophil adhesion and migration. Activation of the integrin Mac-1 is known to be critical for mediating neutrophil adhesion and migration. sCD40L activated Mac-1 in neutrophils and enhanced neutrophil-platelet interactions in wild-type neutrophils, but failed to elicit such responses in CD40-deficient neutrophils. Furthermore, our data show that the protein kinase C zeta (PKCζ) is critically required for sCD40L-induced Mac-1 activation and neutrophil adhesive function. sCD40L strongly stimulated the focal clustering of Mac-1 (CD11b) and the colocalization of Mac-1 with PKCζ in wild-type neutrophils, but had minimal effect in CD40-deficient neutrophils. Blocking PKCζ completely inhibited sCD40L-induced neutrophil firm adhesion. Moreover, sCD40L strongly stimulates neutrophil oxidative burst via CD40-dependent activation of PI3K/NF-KB, but independent of Mac-1 and PKCζ. These findings may contribute to a better understanding of the underlying mechanisms by which sCD40L/CD40 pathway contributes to inflammation and vascular diseases. 相似文献
90.
Epigenetic dysregulation in the developing Down syndrome cortex 总被引:1,自引:0,他引:1
Nady El Hajj Marcus Dittrich Julia Böck Theo F. J. Kraus Indrajit Nanda Tobias Müller 《Epigenetics》2016,11(8):563-578