全文获取类型
收费全文 | 2717篇 |
免费 | 147篇 |
国内免费 | 2篇 |
专业分类
2866篇 |
出版年
2023年 | 37篇 |
2022年 | 85篇 |
2021年 | 137篇 |
2020年 | 60篇 |
2019年 | 67篇 |
2018年 | 105篇 |
2017年 | 66篇 |
2016年 | 119篇 |
2015年 | 129篇 |
2014年 | 145篇 |
2013年 | 200篇 |
2012年 | 193篇 |
2011年 | 181篇 |
2010年 | 114篇 |
2009年 | 98篇 |
2008年 | 123篇 |
2007年 | 114篇 |
2006年 | 108篇 |
2005年 | 89篇 |
2004年 | 98篇 |
2003年 | 75篇 |
2002年 | 70篇 |
2001年 | 42篇 |
2000年 | 30篇 |
1999年 | 21篇 |
1998年 | 21篇 |
1997年 | 18篇 |
1996年 | 10篇 |
1995年 | 15篇 |
1994年 | 11篇 |
1993年 | 13篇 |
1992年 | 15篇 |
1991年 | 17篇 |
1990年 | 11篇 |
1989年 | 11篇 |
1988年 | 15篇 |
1986年 | 12篇 |
1985年 | 18篇 |
1984年 | 9篇 |
1982年 | 7篇 |
1981年 | 10篇 |
1980年 | 9篇 |
1979年 | 9篇 |
1978年 | 14篇 |
1977年 | 10篇 |
1976年 | 9篇 |
1974年 | 9篇 |
1973年 | 11篇 |
1972年 | 7篇 |
1969年 | 9篇 |
排序方式: 共有2866条查询结果,搜索用时 15 毫秒
101.
Huseyin Tombuloglu Ertugrul Filiz Mehtap Aydın Ibrahim Koc 《Journal of plant biochemistry and biotechnology.》2017,26(3):263-273
Sulphur is an important mineral element for plant growth and development. It involves in a number of metabolic processes with crucial functions. This study has performed a genome-wide analysis of sulfate transporter (SULTR) genes in Brachypodium distachyon. Ten putative SULTR genes were identified in Brachypodium genome. BdSULTR genes included 6–17 exons encoding a protein of 647–693 residues with basic nature. BdSULTR proteins included both sulfate_transp (PF00916) and STAS (PF01740) domains. BdSULTRs were classified into 4 groups based on the phylogenetic distribution. Promoter regions of all BdSULTR genes, except for BdSULTR3;3 and 3;5 included the SURECOREATSULTR11 elements. A considerable structural overlap was identified between superimposed SULTR1;3 and 3;1 proteins, indicating that SULTR1 members may also involve in plant stress response/tolerance like SULTR3 members. Microarray and RNA-Seq analyses also revealed the differential expression of SULTR 1 and 3 genes under different biotic/abiotic stresses. Protein–protein interaction partners of BdSULTRs were mainly related with adenylyl-sulfate kinases, 5′-adenylylsulfate reductases, ATP sulfurylases, and acyl carrier proteins. Moreover, expression profiles of identified BdSULTR genes under S-deficiency were analyzed using RT-qPCR. It was revealed that BdSULTR1;1 and 3;1 are highly expressed in plant roots as ~tenfold and ~fivefold, respectively, while BdSULTR2 (~15-fold) and 3;1 (~twofold) are abundantly expressed in leaf tissues. 相似文献
102.
In this paper, we propose a Bayesian design framework for a biosimilars clinical program that entails conducting concurrent trials in multiple therapeutic indications to establish equivalent efficacy for a proposed biologic compared to a reference biologic in each indication to support approval of the proposed biologic as a biosimilar. Our method facilitates information borrowing across indications through the use of a multivariate normal correlated parameter prior (CPP), which is constructed from easily interpretable hyperparameters that represent direct statements about the equivalence hypotheses to be tested. The CPP accommodates different endpoints and data types across indications (eg, binary and continuous) and can, therefore, be used in a wide context of models without having to modify the data (eg, rescaling) to provide reasonable information-borrowing properties. We illustrate how one can evaluate the design using Bayesian versions of the type I error rate and power with the objective of determining the sample size required for each indication such that the design has high power to demonstrate equivalent efficacy in each indication, reasonably high power to demonstrate equivalent efficacy simultaneously in all indications (ie, globally), and reasonable type I error control from a Bayesian perspective. We illustrate the method with several examples, including designing biosimilars trials for follicular lymphoma and rheumatoid arthritis using binary and continuous endpoints, respectively. 相似文献
103.
Aya Ibrahim Danielle Kirkpatrick Laura J. Nixon Dalton C. Ludwick Gianfranco Anfora Tracy C. Leskey 《Journal of Applied Entomology》2020,144(7):589-597
The brown marmorated stink bug, Halyomorpha halys Stål (Hemiptera: Pentatomidae), is an invasive pest that attacks specialty and row crops in North America and Europe. There has been a concerted effort to reduce frequent broad-spectrum insecticide applications made on vulnerable crops. One tool that has emerged recently is the use of long-lasting insecticide-treated nets (LLINs) as a killing agent. Here, we conducted bioassays to evaluate the effect of direct contact on deltamethrin-impregnated LLINs on the behaviour and survivorship of H. halys nymphs and adults in the laboratory. Following exposure at three different durations (1.25, 4.25 or 7.25 min), vertical and horizontal mobility of adults and nymphs and the flight capacity of adults were recorded and compared with individuals that were not exposed (control). Exposure to LLINs reduced the horizontal distance and velocity and increased the angular velocity of adults only but reduced vertical mobility of adults and nymphs. Adult flights were not significantly affected by LLIN exposure. Mortality of adults and nymphs at 7-day post-exposure ranged from 73% to 77% regardless of exposure time. We discuss our findings within the context of the potential for and limitations of deploying LLINs in vulnerable crops to manage H. halys populations. 相似文献
104.
105.
T J McMahon J S Hood B D Nossaman I N Ibrahim C J Feng P J Kadowitz 《Journal of applied physiology》1991,71(5):2012-2018
The effects of SQ 30741, a thromboxane A2 (TxA2) receptor blocking agent, on responses to the TxA2 mimic, U-46619, were investigated in the pulmonary vascular bed of the intact-chest cat under constant-flow conditions. The administration of SQ 30741 in doses of 1-2 mg/kg iv markedly reduced vasoconstrictor responses to U-46619 without altering responses to prostaglandin (PG) F2 alpha or PGD2 and serotonin. SQ 30741 had no significant effect on mean vascular pressures in the cat, and the dose-response curve for U-46619 was shifted to the right in a parallel manner with a similar apparent maximal response. In addition to not altering responses to PGF2 alpha, PGD2 alpha, or serotonin, SQ 30741 (2 mg/kg iv) was without significant effect on pulmonary vasoconstrictor responses to the PGD2 metabolite 9 alpha, 11 beta-PGF2, norepinephrine, angiotensin II, BAY K 8644, endothelin 1, or endothelin 2. Although responses to vasoconstrictor agents, which act through a variety of mechanisms, were not altered, responses to the PG and TxA2 precursor, arachidonic acid, were reduced significantly. The duration of the TxA2 receptor blockade was approximately 30 and 75 min at the 1- and 2-mg/kg iv doses of the antagonist, respectively. The present data show that SQ 30741 selectively blocks TxA2 receptor-mediated responses in a competitive and reversible manner in the pulmonary vascular bed. These data suggest that responses to arachidonic acid are due in large part to the formation of TxA2 and that discrete TxA2 receptors unrelated to receptors activated by PGD2 or PGF2 alpha are most likely located in resistance vessel elements in the feline pulmonary vascular bed. 相似文献
106.
Alessia Ranciaro Michael?C. Campbell Jibril?B. Hirbo Wen-Ya Ko Alain Froment Paolo Anagnostou Maritha?J. Kotze Muntaser Ibrahim Thomas Nyambo Sabah?A. Omar Sarah?A. Tishkoff 《American journal of human genetics》2014,94(4):496-510
In humans, the ability to digest lactose, the sugar in milk, declines after weaning because of decreasing levels of the enzyme lactase-phlorizin hydrolase, encoded by LCT. However, some individuals maintain high enzyme amounts and are able to digest lactose into adulthood (i.e., they have the lactase-persistence [LP] trait). It is thought that selection has played a major role in maintaining this genetically determined phenotypic trait in different human populations that practice pastoralism. To identify variants associated with the LP trait and to study its evolutionary history in Africa, we sequenced MCM6 introns 9 and 13 and ∼2 kb of the LCT promoter region in 819 individuals from 63 African populations and in 154 non-Africans from nine populations. We also genotyped four microsatellites in an ∼198 kb region in a subset of 252 individuals to reconstruct the origin and spread of LP-associated variants in Africa. Additionally, we examined the association between LP and genetic variability at candidate regulatory regions in 513 individuals from eastern Africa. Our analyses confirmed the association between the LP trait and three common variants in intron 13 (C-14010, G-13907, and G-13915). Furthermore, we identified two additional LP-associated SNPs in intron 13 and the promoter region (G-12962 and T-956, respectively). Using neutrality tests based on the allele frequency spectrum and long-range linkage disequilibrium, we detected strong signatures of recent positive selection in eastern African populations and the Fulani from central Africa. In addition, haplotype analysis supported an eastern African origin of the C-14010 LP-associated mutation in southern Africa. 相似文献
107.
Taylan Sekeroglu H Erdem E Yagmur M Gumral R Ersoz R Ilkit M Harbiyeli II 《Mycopathologia》2012,174(3):233-237
Fungal keratitis is a rare but sight-threatening infection of the cornea that may be caused by several fungal pathogens. A delay in diagnosis and inadequate treatment may even lead to loss of the affected eye. Fungal keratitis is often misdiagnosed as bacterial keratitis because isolation and identification of the fungal pathogen is difficult and requires experience, and fungal growth in culture requires time. In this report, a 14-year-old boy with recalcitrant Fusarium solani keratitis, unresponsive to initial therapy, is presented. CLSI M38-A2 in vitro antifungal susceptibility tests demonstrated that only amphotericin B (0.5 μg/ml) had potent activity against F. solani; however, fluconazole (>64 μg/ml), itraconazole (>16 μg/ml), voriconazole (8 μg/ml), and posaconazole (>16 μg/ml) had high minimum inhibitory concentrations. In addition, caspofungin (>16 μg/ml) and anidulafungin (>16 μg/ml) exhibited high minimum effective concentrations. Repeated intrastromal voriconazole injections, topical voriconazole, and caspofungin combined with systemic antifungal agents improved of the corneal lesion with a significant increase in visual acuity. Intrastromal voriconazole injection may be used as an adjunctive treatment method for recalcitrant fungal keratitis with no prominent complications. The intrastromal route could be an effective route of administration of antifungal agents, especially for F. solani keratitis, as in this case. A combination of various antifungal agents administered by different routes prevented loss of the eye. 相似文献
108.
Ibrahim GM Akiyama T Ochi A Otsubo H Smith ML Taylor MJ Donner E Rutka JT Snead OC Doesburg SM 《PloS one》2012,7(6):e39326
Although children with epilepsy exhibit numerous neurological and cognitive deficits, the mechanisms underlying these impairments remain unclear. Synchronization of oscillatory neural activity in the gamma frequency range (>30 Hz) is purported to be a mechanism mediating functional integration within neuronal networks supporting cognition, perception and action. Here, we tested the hypothesis that seizure-induced alterations in gamma synchronization are associated with functional deficits. By calculating synchrony among electrodes and performing graph theoretical analysis, we assessed functional connectivity and local network structure of the hand motor area of children with focal epilepsy from intracranial electroencephalographic recordings. A local decrease in inter-electrode phase synchrony in the gamma bands during ictal periods, relative to interictal periods, within the motor cortex was strongly associated with clinical motor weakness. Gamma-band ictal desychronization was a stronger predictor of deficits than the presence of the seizure-onset zone or lesion within the motor cortex. There was a positive correlation between the magnitude of ictal desychronization and impairment of motor dexterity in the contralateral, but not ipsilateral hand. There was no association between ictal desynchronization within the hand motor area and non-motor deficits. This study uniquely demonstrates that seizure-induced disturbances in cortical functional connectivity are associated with network-specific neurological deficits. 相似文献
109.
This study was undertaken to investigate the effect of plasma pre-treatment, followed by enzymatic treatment in the absence and presence of bleaching agent on the properties of linen and linen-containing fabrics. Different plasma gases (air, oxygen and nitrogen), enzymes (acid-cellulases, neutral-cellulase and alkaline-pectinase) as well as bleaching agents (peracetic acid and H2O2) were used. The changes in physico-mechanical properties, surface morphology and dyeing properties of the treated substrates have been investigated. The obtained results indicated that plasma pre-treatment followed by subsequent acid-cellulases/peracetic acid or alkaline-pectinase/H2O2 treatment result in: a dramatic improvement in hydrophilicity and wettability as well as in the degree of whiteness of the treated substrates, an improvement in reduction of surface roughness and extent of post-reactive dyeing, along with a weight loss and a drop in the tensile strength. The extent of surface modification as well as the changes in the above-mentioned properties are governed by the characteristics of the substrate, the plasma gas, the nature and dose of the used enzyme, as well as the type of bleaching agent and additive. The optimal treatment sequence for attaining better performance properties was O2-plasma followed by alkaline-pectinase/H2O2 treatment in presence of PEG 400. 相似文献
110.
Mohamed Aly Radwan Shehata Mohamed Ibrahim Kassem Mahmoud Mohamed Abu-Elamayem Entsar Khalil El-Maadawy 《Archives Of Phytopathology And Plant Protection》2013,46(5):345-352
Abstract The aim of the present study was to formulate six different plant seed oils namely canola, cotton, flax, olive, sesame and soybean as emulsifiable concentrates. The composition of the formulation comprises at least one organic solvent, one surfactant and one plant oil. Physico-chemical properties of the formulated oils (emulsion stability test, cold stability and heat stability tests) were measured. The successfully emulsified oils were evaluated for nematicidal activity against Meloidogyne incognita infecting tomato plants under greenhouse conditions. Emulsified canola oil proved to be the most effective oil as a protectant against M. incognita infection to tomatoes followed by soybean, cotton, flax and sesame oil. In addition, employing a high rate of the tested emulsified oils gave higher activity in suppressing nematodes both in the soil and in tomato roots than using a low rate. Moreover, all tested formulated oils at both rates of application had no adverse effect on the growth of tomato plants except sesame oil which significantly decreased the shoot length when compared to the control. The prepared plant oils might be used as potential sources for sustainable eco-friendly botanical nematicides to protect plants from nematode attack. 相似文献