全文获取类型
收费全文 | 2587篇 |
免费 | 174篇 |
国内免费 | 4篇 |
出版年
2023年 | 23篇 |
2022年 | 36篇 |
2021年 | 77篇 |
2020年 | 47篇 |
2019年 | 48篇 |
2018年 | 66篇 |
2017年 | 63篇 |
2016年 | 86篇 |
2015年 | 114篇 |
2014年 | 168篇 |
2013年 | 208篇 |
2012年 | 200篇 |
2011年 | 243篇 |
2010年 | 151篇 |
2009年 | 131篇 |
2008年 | 160篇 |
2007年 | 161篇 |
2006年 | 140篇 |
2005年 | 104篇 |
2004年 | 96篇 |
2003年 | 73篇 |
2002年 | 92篇 |
2001年 | 18篇 |
2000年 | 10篇 |
1999年 | 23篇 |
1998年 | 18篇 |
1997年 | 13篇 |
1996年 | 6篇 |
1995年 | 7篇 |
1994年 | 13篇 |
1993年 | 5篇 |
1992年 | 13篇 |
1991年 | 11篇 |
1990年 | 6篇 |
1989年 | 6篇 |
1988年 | 7篇 |
1987年 | 6篇 |
1986年 | 5篇 |
1985年 | 10篇 |
1983年 | 6篇 |
1980年 | 7篇 |
1977年 | 7篇 |
1975年 | 5篇 |
1974年 | 6篇 |
1973年 | 9篇 |
1972年 | 5篇 |
1970年 | 13篇 |
1969年 | 5篇 |
1966年 | 4篇 |
1965年 | 8篇 |
排序方式: 共有2765条查询结果,搜索用时 843 毫秒
91.
92.
Ravi Pandiselvam Venkatachalam Thirupathi Striramasarma Mohan Palanisamy Vennila Doraiswamy Uma Sultan Shahir Sugumar Anandakumar 《Journal of Applied Entomology》2019,143(4):451-459
Extending the storage life of legumes by protecting it from the Callosobruchus maculatus infestation is a major concern for the producers, processors and exporters. Legume processing industry requires “greener” alternatives to the conventional fumigants. Gaseous ozone has a great potential as an insect management strategy that is suited for this niche. Nevertheless, the efficacy of ozone against C. maculatus is yet unknown. A laboratory study was conducted to test the insecticidal effect of ozone in controlling the infestation of C. maculatus in green gram. We have determined the concentration of ozone exposure time–mortality relationship for all the stages of C. maculatus that were exposed to 500–1,500 ppmv ozone. The percentages of mortality for different stages of C. maculatus increased with the increase in ozone concentration and exposure time. It was documented that adult stage is least tolerant to ozone (500 ppmv for 274.40 min exposure required to kill 90%), whereas the most tolerant stage is pupa (500 ppmv for 1816.54 min is required to kill 90%). The results indicate that gaseous ozone is the attractive alternative to the synthetic fumigants. 相似文献
93.
Ravi V Mural Marcin Grzybowski Chenyong Miao Alyssa Damke Sirjan Sapkota Richard E Boyles Maria G Salas Fernandez Patrick S Schnable Brandi Sigmon Stephen Kresovich James C Schnable 《Genetics》2021,218(3)
Community association populations are composed of phenotypically and genetically diverse accessions. Once these populations are genotyped, the resulting marker data can be reused by different groups investigating the genetic basis of different traits. Because the same genotypes are observed and scored for a wide range of traits in different environments, these populations represent a unique resource to investigate pleiotropy. Here, we assembled a set of 234 separate trait datasets for the Sorghum Association Panel, a group of 406 sorghum genotypes widely employed by the sorghum genetics community. Comparison of genome-wide association studies (GWAS) conducted with two independently generated marker sets for this population demonstrate that existing genetic marker sets do not saturate the genome and likely capture only 35–43% of potentially detectable loci controlling variation for traits scored in this population. While limited evidence for pleiotropy was apparent in cross-GWAS comparisons, a multivariate adaptive shrinkage approach recovered both known pleiotropic effects of existing loci and new pleiotropic effects, particularly significant impacts of known dwarfing genes on root architecture. In addition, we identified new loci with pleiotropic effects consistent with known trade-offs in sorghum development. These results demonstrate the potential for mining existing trait datasets from widely used community association populations to enable new discoveries from existing trait datasets as new, denser genetic marker datasets are generated for existing community association populations. 相似文献
94.
95.
Luciana de Brito Vargas Marcia H Beltrame Brenda Ho Wesley M Marin Ravi Dandekar Gonzalo Montero-Martín Marcelo A Fernndez-Via A Magdalena Hurtado Kim R Hill Luiza T Tsuneto Mara H Hutz Francisco M Salzano Maria Luiza Petzl-Erler Jill A Hollenbach Danillo G Augusto 《Molecular biology and evolution》2022,39(1)
The killer-cell immunoglobulin-like receptors (KIR) recognize human leukocyte antigen (HLA) molecules to regulate the cytotoxic and inflammatory responses of natural killer cells. KIR genes are encoded by a rapidly evolving gene family on chromosome 19 and present an unusual variation of presence and absence of genes and high allelic diversity. Although many studies have associated KIR polymorphism with susceptibility to several diseases over the last decades, the high-resolution allele-level haplotypes have only recently started to be described in populations. Here, we use a highly innovative custom next-generation sequencing method that provides a state-of-art characterization of KIR and HLA diversity in 706 individuals from eight unique South American populations: five Amerindian populations from Brazil (three Guarani and two Kaingang); one Amerindian population from Paraguay (Aché); and two urban populations from Southern Brazil (European and Japanese descendants from Curitiba). For the first time, we describe complete high-resolution KIR haplotypes in South American populations, exploring copy number, linkage disequilibrium, and KIR–HLA interactions. We show that all Amerindians analyzed to date exhibit the lowest numbers of KIR–HLA interactions among all described worldwide populations, and that 83–97% of their KIR–HLA interactions rely on a few HLA-C molecules. Using multiple approaches, we found signatures of strong purifying selection on the KIR centromeric region, which codes for the strongest NK cell educator receptors, possibly driven by the limited HLA diversity in these populations. Our study expands the current knowledge of KIR genetic diversity in populations to understand KIR–HLA coevolution and its impact on human health and survival. 相似文献
96.
Lucas R. Struble Audrey L. Smith William E. Lutz Gabrielle Grubbs Satish Sagar Kenneth W. Bayles Prakash Radhakrishnan Surender Khurana Dalia ElGamal Gloria E. O. Borgstahl 《Protein science : a publication of the Protein Society》2022,31(5)
The COVID‐19 pandemic caused by SARS‐CoV‐2 infection has led to socio‐economic shutdowns and the loss of over 5 million lives worldwide. There is a need for the identification of therapeutic targets to treat COVID‐19. SARS‐CoV‐2 spike is a target of interest for the development of therapeutic targets. We developed a robust SARS‐CoV‐2 S spike expression and purification protocol from insect cells and studied four recombinant SARS‐CoV‐2 spike protein constructs based on the original SARS‐CoV‐2 sequence using a baculovirus expression system: a spike protein receptor‐binding domain that includes the SD1 domain (RBD) coupled to a fluorescent tag (S‐RBD‐eGFP), spike ectodomain coupled to a fluorescent tag (S‐Ecto‐eGFP), spike ectodomain with six proline mutations and a foldon domain (S‐Ecto‐HexaPro(+F)), and spike ectodomain with six proline mutations without the foldon domain (S‐Ecto‐HexaPro(‐F)). We tested the yield of purified protein expressed from the insect cell lines Spodoptera frugiperda (Sf9) and Trichoplusia ni (Tni) and compared it to previous research using mammalian cell lines to determine changes in protein yield. We demonstrated quick and inexpensive production of functional glycosylated spike protein of high purity capable of recognizing and binding to the angiotensin converting enzyme 2 (ACE2) receptor. To further confirm functionality, we demonstrate binding of eGFP fused construct of the spike ectodomain (S‐Ecto‐eGFP) to surface ACE2 receptors on lung epithelial cells by flow cytometry analysis and show that it can be decreased by means of receptor manipulation (blockade or downregulation). 相似文献
97.
98.
Hoti SL Vasuki V Lizotte MW Patra KP Ravi G Vanamail P Manonmani A Sabesan S Krishnamoorthy K Williams SA 《Bulletin of entomological research》2001,91(2):87-92
An Hha 1 based polymerase chain reaction (PCR) assay developed for the detection of Brugia malayi, the causative agent of Brugian lymphatic filariasis, was evaluated for its sensitivity in the laboratory and for its usefulness in measuring changes in transmission of the disease in the field. Laboratory studies showed that the new assay was highly sensitive in comparison with the standard dissection and microscopy technique. The assay can detect as little as 4 pg of parasite DNA or a single microfilaria in pools of up to 100 mosquitoes. The optimum pool size for convenience was found to be 50 mosquitoes per pool. The efficacy of PCR assay was evaluated in filariasis control programmes in operation in endemic areas of Kerala State, South India. The infection rates obtained by the Hha I PCR assay and the conventional dissection and microscopy technique were 1.2% and 1.7% respectively in operational areas and 8.3% and 4.4% respectively, in check areas, which were not significantly different (P < 0.05). Thus, the Hha I PCR assay was found to be as sensitive as the conventional technique and hence it can be used as a new epidemiological tool for assessing parasite infection in field-collected mosquitoes. 相似文献
99.
Ravi RK McMahon M Yangang Z Williams JR Dillehay LE Nelkin BD Mabry M 《Journal of cellular biochemistry》1999,72(4):458-469
Prostate cancer is the most commonly diagnosed neoplasm in men. LNCaP cells continue to possess many of the molecular characteristics of in situ prostate cancer. These cells lack ras mutations, and mitogen-activated protein kinase (MAPK) is not extensively phosphorylated in these cells. To determine the effects of ras/raf/MAPK pathway activation in these cells, we transfected LNCaP cells with an activatable form of c-raf-1(deltaRaf-1:ER). Activation of deltaRaf-1:ER, with resultant MAPK activation, reduced plating efficiency and soft agarose cloning efficiency 30-fold in LNCaP cells. Cell cycle distribution showed an accumulation of cells in G1 and was associated with the induction of CDK inhibitor p21WAF1/CIP1 at the protein and mRNA levels. p21WAF1/CIP1 mRNA stability was increased after deltaRaf-1:ER activation. In addition, activated deltaRaf-1:ER induced the senescence associated-beta-galactosidase in LNCaP cells. These data demonstrate that raf activation can activate growth inhibitory pathways leading to growth suppression in prostate carcinoma cells and also suggest that raf/MEK/MAPK pathway activation, rather than inhibition, may be a therapeutic target for some human prostate cancer cells. 相似文献
100.
Nancy L. Wilczynski R. Brian Haynes John N. Lavis Ravi Ramkissoonsingh Alexandra E. Arnold-Oatley The HSR Hedges Team 《CMAJ》2004,171(10):1179-1185