全文获取类型
收费全文 | 799篇 |
免费 | 126篇 |
国内免费 | 349篇 |
出版年
2023年 | 16篇 |
2022年 | 21篇 |
2021年 | 25篇 |
2020年 | 66篇 |
2019年 | 51篇 |
2018年 | 15篇 |
2017年 | 16篇 |
2016年 | 41篇 |
2015年 | 70篇 |
2014年 | 37篇 |
2013年 | 89篇 |
2012年 | 64篇 |
2011年 | 43篇 |
2010年 | 63篇 |
2009年 | 60篇 |
2008年 | 58篇 |
2007年 | 55篇 |
2006年 | 45篇 |
2005年 | 45篇 |
2004年 | 42篇 |
2003年 | 40篇 |
2002年 | 32篇 |
2001年 | 30篇 |
2000年 | 27篇 |
1999年 | 27篇 |
1998年 | 27篇 |
1997年 | 6篇 |
1996年 | 16篇 |
1995年 | 15篇 |
1994年 | 10篇 |
1993年 | 12篇 |
1992年 | 19篇 |
1991年 | 10篇 |
1990年 | 7篇 |
1989年 | 8篇 |
1988年 | 12篇 |
1987年 | 7篇 |
1986年 | 7篇 |
1985年 | 8篇 |
1984年 | 3篇 |
1983年 | 6篇 |
1982年 | 15篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有1274条查询结果,搜索用时 15 毫秒
91.
92.
Atul S. THAKARE Umesh P. BARKHADE Vrushali N. PAWADE Shivcharan M. THAKARE 《Entomological Research》2010,40(3):177-181
The present study was undertaken to determine the genetics of Cry1C resistance in Spodoptera litura. Selection of S. litura (Fab.) with Cry1C was done for eight generations to develop resistance. Reciprocal crosses between resistant and susceptible populations were made to understand the population genetics of Cry1C resistance in S. litura. Generation wise selection with Cry1C was evaluated for resistance development in S. litura. The LC50 of Cry1C was 0.14 µg/cm2 for the first selected generation and it increased to 23.98 µg/cm2 after eight selected generations, which is a 285.47-fold increase in resistance compared with the susceptible strain. The estimated realized heritability (h2) after eight generations of selection with Cry1C insecticidal protein was 0.44. The number of generations required for the tenfold increase in LC50 (1/R) was estimated to be 3.33. Response to Cry1C selection in S. litura was 0.30, the estimated selection differential was 0.69 and the pheonotypic standard deviation (dP) was 0.24. Reciprocal crosses between Cry1C resistant and susceptible strain of S. litura showed autosomal resistance. 相似文献
93.
Aminopeptidase N (APN) isoforms were identified as candidate receptors for Bacillus thuringiensis Cry toxins from the midgut of several insect species. In this study a partial cDNA encoding aminopeptidase (slfbAPN) was
cloned from fat body of the moth Spodoptera litura. In the deduced amino acid sequence the characteristic metallopeptidase sequences, HEXXHX18E and GAMENWG were conserved but the sequence showed only 33–39% identity to other insect APNs, which were also reported to
be Cry toxin receptors. The presence of a putative GPI anchor signal sequence at the C-terminus indicated that it is a membrane-anchored protein. The slfbAPN expression was restricted to the fat body as suggested
by northern blot analysis of different tissues. Biochemical analyses including immunoblotting, ligand blotting and lectin
blotting, demonstrated that slfbAPN is a membrane-anchored glycoprotein in the fat body and it binds to Cry toxins.
The nucleotide sequence shown here has been submitted to the GenBank sequence data bank and is available under accession number
EF372603. 相似文献
94.
Phagocytosis is a hemocytic behavior against bacterial infection. An entomopathogenic bacterium, Xenorhabdus nematophila, inhibits immune responses of target insects and causes hemolymph septicemia. This study analyzed how X. nematophila could inhibit phagocytosis to increase its pathogenicity. Granular cells and plasmatocytes were the main phagocytic hemocytes of Spodoptera exigua determined by observing fluorescence-labeled bacteria in the cytosol. X. nematophila significantly inhibited phagocytosis of both hemocytes, while heat-killed X. nematophila lost its inhibitory potency. However, co-injection of X. nematophila with arachidonic acid did not show any significant inhibition of hemocyte phagocytosis. In fact, hemocytes of S. exigua infected with X. nematophila showed significant reduction in phospholipase A(2) (PLA(2)) activity. Dexamethasone, a specific PLA(2) inhibitor, significantly inhibited phagocytosis of both cell types. However, the inhibitory effect of dexamethasone was recovered by addition of arachidonic acid. Incubation of hemocytes with benzylideneacetone, a metabolite of X. nematophila, inhibited phagocytosis in a dose-dependent manner. These results suggest that X. nematophila produces and secretes PLA(2) inhibitor(s), which in turn inhibit the phagocytic response of hemocytes. 相似文献
95.
Li Q Nance MR Kulikauskas R Nyberg K Fehon R Karplus PA Bretscher A Tesmer JJ 《Journal of molecular biology》2007,365(5):1446-1459
Ezrin/radixin/moesin (ERM) family members provide a regulated link between the cortical actin cytoskeleton and the plasma membrane to govern membrane structure and organization. Here, we report the crystal structure of intact insect moesin, revealing that its essential yet previously uncharacterized alpha-helical domain forms extensive interactions with conserved surfaces of the band four-point-one/ezrin/radixin/moesin (FERM) domain. These interdomain contacts provide a functional explanation for how PIP(2) binding and tyrosine phosphorylation of ezrin lead to activation, and provide an understanding of previously enigmatic loss-of-function missense mutations in the tumor suppressor merlin. Sequence conservation and biochemical results indicate that this structure represents a complete model for the closed state of all ERM-merlin proteins, wherein the central alpha-helical domain is an active participant in an extensive set of inhibitory interactions that can be unmasked, in a rheostat-like manner, by coincident regulatory factors that help determine cell polarity and membrane structure. 相似文献
96.
97.
98.
The effect of an optical brightener on the insecticidal activity of a Spodoptera littoralis (Boisduval) (Lepidoptera: Noctuidae) nucleopolyhedrovirus (SpliNPV) were examined in three instars of S. littoralis. LD50 values of the SpliNPV were reduced from 33 to <5, 73 to 5.7 and 342 321 to 288 412 occlusion bodies for second, third and fourth instars, respectively, by the addition of 1% Tinopal UNPA-GX. Relative potencies were >66, 12.8, and 1.2 for second-. third- and fourth-instar S. littoralis larvae, respectively. Relative mortality between the treatments with and without the brightener decreased from third- to fourth-stage larvae. In terms of speed of kill, the ST50 values of the baculovirus-infected larva were reduced from 210 to 159, 213 to 147, and 207 to 165 h for second-, third- and fourth-instar larvae, respectively, by the addition of the optical brightener at biologically equivalent doses. 相似文献
99.
Ton J D'Alessandro M Jourdie V Jakab G Karlen D Held M Mauch-Mani B Turlings TC 《The Plant journal : for cell and molecular biology》2007,49(1):16-26
Plants counteract attack by herbivorous insects using a variety of inducible defence mechanisms. The production of toxic proteins and metabolites that instantly affect the herbivore's development are examples of direct induced defence. In addition, plants may release mixtures of volatile organic compounds (VOCs) that indirectly protect the plant by attracting natural enemies of the herbivore. Recent studies suggest that these VOCs can also prime nearby plants for enhanced induction of defence upon future insect attack. However, evidence that this defence priming causes reduced vulnerability to insects is sparse. Here we present molecular, chemical and behavioural evidence that VOC-induced priming leads to improved direct and indirect resistance in maize. A differential hybridization screen for inducible genes upon attack by Spodoptera littoralis caterpillars identified 10 defence-related genes that are responsive to wounding, jasmonic acid (JA), or caterpillar regurgitant. Exposure to VOCs from caterpillar-infested plants did not activate these genes directly, but primed a subset of them for earlier and/or stronger induction upon subsequent defence elicitation. This priming for defence-related gene expression correlated with reduced caterpillar feeding and development. Furthermore, exposure to caterpillar-induced VOCs primed for enhanced emissions of aromatic and terpenoid compounds. At the peak of this VOC emission, primed plants were significantly more attractive to parasitic Cotesia marginiventris waSPS. This study shows that VOC-induced priming targets a specific subset of JA-inducible genes, and links these responses at the molecular level to enhanced levels of direct and indirect resistance against insect attack. 相似文献
100.