全文获取类型
收费全文 | 3394篇 |
免费 | 307篇 |
国内免费 | 2篇 |
出版年
2022年 | 25篇 |
2021年 | 62篇 |
2020年 | 25篇 |
2019年 | 36篇 |
2018年 | 51篇 |
2017年 | 46篇 |
2016年 | 99篇 |
2015年 | 152篇 |
2014年 | 132篇 |
2013年 | 171篇 |
2012年 | 211篇 |
2011年 | 206篇 |
2010年 | 155篇 |
2009年 | 135篇 |
2008年 | 189篇 |
2007年 | 172篇 |
2006年 | 146篇 |
2005年 | 145篇 |
2004年 | 161篇 |
2003年 | 160篇 |
2002年 | 155篇 |
2001年 | 51篇 |
2000年 | 51篇 |
1999年 | 50篇 |
1998年 | 61篇 |
1997年 | 39篇 |
1996年 | 42篇 |
1995年 | 36篇 |
1994年 | 40篇 |
1993年 | 39篇 |
1992年 | 59篇 |
1991年 | 52篇 |
1990年 | 48篇 |
1989年 | 54篇 |
1988年 | 43篇 |
1987年 | 33篇 |
1986年 | 33篇 |
1985年 | 31篇 |
1984年 | 36篇 |
1983年 | 24篇 |
1982年 | 22篇 |
1981年 | 24篇 |
1980年 | 27篇 |
1979年 | 26篇 |
1978年 | 27篇 |
1977年 | 21篇 |
1976年 | 20篇 |
1975年 | 12篇 |
1974年 | 16篇 |
1972年 | 11篇 |
排序方式: 共有3703条查询结果,搜索用时 15 毫秒
111.
Monique Vuillaume 《Journal of insect physiology》1976,22(8):1053-1056
In previous communications we have reported the role of red light on the determinism of the pupal diapause of Pieris brassicae (630 to 670 nm, wavelengths corresponding to the maximum of absorption of pterobilin, the blue bile pigment present in the integument and haemolymph).Red light suppresses the diapausing effect of the 9-hr/24-hr photophase of white light (identical energy in both and similar to the energy under natural conditions). The activity of red light in two experimental conditions: 9-hr white light followed by 15 hr of red lights of different intensities, and 9-hr red lights of different intensities followed by 15 hr darkness is examined. The photoperiodic determinism of pupal diapause is discussed. 相似文献
112.
113.
Ribosomal genes in eukaryotes are highly redundant. Considerable variation in the level of redundancy among species, especially in higher plants, has been reported; but except for deletion and duplication mutants, it is generally accepted that intraspecific variability in redundancy level is small. We have examined the level of redundancy in several lines of maize by DNA-rRNA saturation hybridization. The amount of nuclear DNA which hybridizes with rRNA in the ten lines examined varied from 0.24% to 0.50%. The number of rRNA genes per diploid genome thus ranges from 1.12 x 104 to 2.32 x 104. Results also indicate that the level of redundancy is genetically transmitted. 相似文献
114.
Experimental infection of fertilized pike eggs with 'red-disease' virus produced 100% mortality in the fry. This mortality was associated with a disease that had previously been described as hydrocephalus internus, indicating that 'red-disease' and hydrocephalus are different manifestations of the same disease. The name pike fry rhabdovirus disease (PFRD) is suggested for the disease complex, and the name pike fry rhabdovirus (PFR) for the causative agent. Exposure of PFR to a Wescodyne * solution containing 25 ppm of iodine resulted in an inactivation of at least 99–99% of viral activity within 30 sec. Experimental egg transmission of PFR could be interrupted by disinfecting the eggs in a Wescodyne solution, suggesting that the virus was located on the egg surface. Conclusive evidence of a naturally occurring vertical transmission in pike culture is still lacking because, using FHM cells as a detection system, PFR could not be found in spawners and their sexual products. The susceptibility of pike fry to PFR rapidly decreases at increasing age. 相似文献
115.
Mercedes Hernandez-Asensio Juan M. Ramirez Francisca F. Del Campo 《Archives of microbiology》1975,103(1):155-162
The uptake of methyl α-d-glucopyranoside (α-MG) by Escherichia coli K12 was decreased by the addition of substrates which stimulated the rate of oxygen consumption by the cells. The inhibition, which occurred only at non-saturating concentrations of α-MG, was not the result of a stimulation of the rate of exit of intracellular α-MG, and was abolished by the presence of carbonyl cyanide m-chlorophenylhydrazone or sodium azide. Since those drugs inhibit energy conservation at the respiratory chain and did not alter significantly the rate of oxygen consumption under the conditions for the assay of α-MG uptake, it appears that the inhibition of the transport system by respirable substrates is mediated by some form of energy derived from respiration. 相似文献
116.
117.
Drought‐stress and plant resistance affect herbivore performance and proteome: the case of the green peach aphid Myzus persicae (Hemiptera: Aphididae) 下载免费PDF全文
Jaime A. Verdugo Marie‐Helene Sauge Jean‐Philippe Lacroze Frederic Francis Claudio C. Ramirez 《Physiological Entomology》2015,40(4):265-276
Little is known about the simultaneous effects of drought stress and plant resistance on herbivorous insects. By subjecting the green peach aphid Myzus persicae Sulzer to well‐watered and drought‐stressed plants of both susceptible and resistant peach (Prunus persica), the effects of both stressors on aphid performance and proteomics are tested. Overall, the influence of the water treatment on aphid performance is less pronounced than the effect of host plant genetic resistance. On the susceptible cultivar, aphid survival, host acceptance and ability to colonize the plant do not depend on water treatment. On the resistant cultivar, aphid survival and ability to colonize are higher on drought‐stressed than on well‐watered plants. A study examining the pattern of protein expression aiming to explain the variation in aphid performance finds higher protein expression in aphids on the drought‐stressed susceptible cultivars compared with the well‐watered ones. In the susceptible cultivar, the regulated proteins are related to energy metabolism and exoskeleton functionality, whereas, in the resistant cultivar, the proteins are involved with the cytoskeleton. Comparison of the protein expression ratios for resistant versus susceptible plants reveals that four proteins are down‐regulated in well‐watered plants and 15 proteins are down‐regulated in drought‐stressed plants. Drought stress applied to the susceptible cultivar induces the regulation of proteins in M. persicae that enable physiological adaptation to maintain an almost unaltered aphid performance. By contrast, for aphids on the resistant cultivar subjected to drought stress, the down‐regulation of proteins responds to an induced host susceptibility effect. 相似文献
118.
Rosa Angela Raccuglia Gabriella Bellone Kristina Loziene Franco Piozzi Sergio Rosselli Antonella Maggio Maurizio Bruno Monique S.J. Simmonds 《Phytochemistry》2010,71(17-18):2087-2091
From the aerial parts of Scutellaria hastifolia, family Lamiaceae (Labiatae), seven neo-clerodane diterpenoids (hastifolins A–G) were isolated. The products are similar to the known scuteparvin and are characterized by being trans-cinnamoyl derivatives. Structures and stereochemistry were determined by intensive NMR investigation. Six of the products form three pairs of epimers at C-13. Hastifolins A–C showed significant antifeedant activity. 相似文献
119.
Jessica Voisin Francesca Farina Swati Naphade Morgane Fontaine Kizito‐Tshitoko Tshilenge Carlos Galicia Aguirre Alejandro Lopez‐Ramirez Julia Dancourt Aurélie Ginisty Satish Sasidharan Nair Kuruwitage Lakshika Madushani Ningzhe Zhang Fran?ois‐Xavier Lejeune Marc Verny Judith Campisi Lisa M. Ellerby Christian Neri 《Aging cell》2020,19(11)