全文获取类型
收费全文 | 1235篇 |
免费 | 35篇 |
国内免费 | 37篇 |
出版年
2023年 | 8篇 |
2022年 | 7篇 |
2021年 | 18篇 |
2020年 | 20篇 |
2019年 | 14篇 |
2018年 | 21篇 |
2017年 | 10篇 |
2016年 | 9篇 |
2015年 | 18篇 |
2014年 | 19篇 |
2013年 | 53篇 |
2012年 | 20篇 |
2011年 | 18篇 |
2010年 | 14篇 |
2009年 | 30篇 |
2008年 | 28篇 |
2007年 | 33篇 |
2006年 | 37篇 |
2005年 | 43篇 |
2004年 | 51篇 |
2003年 | 55篇 |
2002年 | 47篇 |
2001年 | 47篇 |
2000年 | 40篇 |
1999年 | 33篇 |
1998年 | 34篇 |
1997年 | 45篇 |
1996年 | 41篇 |
1995年 | 32篇 |
1994年 | 44篇 |
1993年 | 53篇 |
1992年 | 42篇 |
1991年 | 35篇 |
1990年 | 21篇 |
1989年 | 19篇 |
1988年 | 35篇 |
1987年 | 28篇 |
1986年 | 23篇 |
1985年 | 20篇 |
1984年 | 15篇 |
1983年 | 11篇 |
1982年 | 17篇 |
1981年 | 17篇 |
1980年 | 12篇 |
1978年 | 8篇 |
1977年 | 10篇 |
1976年 | 11篇 |
1975年 | 9篇 |
1974年 | 10篇 |
1973年 | 13篇 |
排序方式: 共有1307条查询结果,搜索用时 15 毫秒
1.
Activity, control and primer requirements of starch phosphorylase in developing barley endosperm were investigated. Phosphorylase was detected in endosperm extracts from 3 days after anthesis. Unprimed activity was predominant between 2 and 10 days after anthesis, when it constituted 70–80% of total activity, but this proportion declined rapidly as the grain developed. The existence of at least 2 isoenzymes was indicated by studies of pH dependence and phosphate inhibition, and was further supported by acrylamide gel electrophoresis and column chromatography using DEAE-cellulose. The two isoenzymes which ere possibly both glyco proteins, appear in barley endosperm soon after anthesis. One appears capable of unprimed activity, and may be associated with the initiation of a-1,2 glucans, which then serve as primers for starch synthetase. This disappears by 13–15 days after anthesis. The other isoenzyme is capable of some unprimed activity but undergoes modification between 15 and 20 days after anthesis, resulting in the loss of unprimed activity. The relevance of the results to initiation of starch synthesis and to starch synthetase in amyloplasts is discussed. 相似文献
2.
Jerry W. McClure 《Phytochemistry》1974,13(7):1065-1069
Five-day-old etiolated barley shoots respond to brief illumination with red light by increasing their level of PAL ca 50% within 5 hr. When assayed s 相似文献
3.
N. Tofangsazi S. Shahrokhi A. A. Talebi 《Archives Of Phytopathology And Plant Protection》2013,46(5):484-492
The greenbugs, Schizaphis graminum (Rondani) were collected from the barley fields in Isfahan region of Iran. The aphid colonies were maintained on each of six barley cultivars including Karoon, Kavir, Zarjoo, Nosrat, Afzal and Rihane. All the experiments were done on the mentioned barley varieties at 26 ± 1°C, 60 ± 5% relative humidity (RH) and at a photoperiod of 16:8 (L:D) h. The shortest and longest developmental times were obtained on Nosrat 6.35 ± 0.11 and Rihane 6.75 ± 0.07 days, respectively. The survivorship of immature stages varied from 71.95% on Nosrat to 82.14% on Zarjoo. The total number of offsprings were 71.05 and 63.22 nymphs per female on Kavir and Karoon. The highest and lowest r m values were observed on Kavir (0.336 ± 0.005) and Rihane (0.299 ± 0.008), respectively. The statistical analysis of jackknife did not show a significant influence of the tested barley varieties for the mean generation time and a similar procedure of difference for λ and r m was estimated. 相似文献
4.
Ryohei Yamaoka Hiroshi Fukami Shoziro Ishii 《Bioscience, biotechnology, and biochemistry》2013,77(10):1971-1977
The sex pheromone produced by adult females of the potato tuberworm moth was isolated from unmated female moths reared in the laboratory. The gas Chromatographic and mass spectrometric data suggested the pheromone to be a tridecatrienyl acetate. The isolated pheromone was subjected to partial hydrogenation with hydrazine and hydrogen peroxide and subsequent ozonolysis to produce a mixture of ω-acetoxy-alkanals. They were identified by mass Chromatographic technique as 4-acetoxy-butanal, 7-acetoxy-heptanal, and 10-acetoxy-decanal respectively. Consequently, the pheromone was identified as 4,7,10-tridecatrienyl acetate except the geometric configuration. 相似文献
5.
Greenhouse tests were conducted to determine the effects of soil temperature and texture on development of Pratylenchus scribneri and the pathogenicity and reproductive rates of this nematode on selected crop plants. In a sandy loam soil, greatest numbers of P. scribneri were found at 30 and 35 C on sudangrass and sugarbeet, respectively. In a silty clay loam, the nematode reproduced best at 35 C on sugarbeet. Higher populations of P. scribneri were found in the sandy loam than silty clay loam soil at corresponding temperatures. In a pathogenicity test, top and root growth of sudangrass and barley were suppressed by the nematode, whereas no significant growth inhibition was found on wheat and alfalfa. Tests with other vegetable and field crops indicated wide variance in nematode reproduction. 相似文献
6.
Phosphate influx and extracellular phosphatase activity in barley roots and rose cells 总被引:4,自引:0,他引:4
R. B. LEE 《The New phytologist》1988,109(2):141-148
7.
《Bioscience, biotechnology, and biochemistry》2013,77(12):2762-2765
Comparative two-dimensional electrophoresis showed six proteins, which were significantly produced in the root of salt-tolerant barley. These proteins were identified as stress/defense-related proteins that do not scavenge reactive oxygen species directly, suggesting that salt-tolerant barley develops not only an antioxidative system, but also physical and biochemical changes to cope with salt stress. 相似文献
8.
J. K. SCHJOERRING A. KYLLINGSBAEK J. V. MORTENSEN S. BYSKOV-NIELSEN 《Plant, cell & environment》1993,16(2):169-178
The activities of glutamine synthetase (GS) and glutamate synthase (GOGAT) in different leaves of field-grown spring barley were measured during the reproductive growth phase in 2 consecutive years. Concurrently, the contents of soluble ammonium ions and free amides in the leaves were determined. The studies were carried out to investigate the relationship between variations in these parameters and emission of NH3 from the plant foliage. GS and GOGAT activities declined very rapidly with leafage. The decline in enzyme activities was followed by an increase in soluble ammonium ions and amides in the leaf tissues. During the same period, about 75% of leaf and stem nitrogen was reallocated to the developing ear. The amount of NH3 volatilized from the foliage during the reproductive growth phase amounted to about 1% of the reallocated nitrogen. The experimental years were characterized by very favourable conditions for grain dry matter formation and for re-utilization of nitrogen mobilized from leaves and stems. Ammonia volatilization occurring under conditions with declining GS and GOGAT activities and increasing tissue concentrations of NH4+ may be useful in protecting the plant from accumulation of toxic NH3 and NH4+ concentrations in the tissues. 相似文献
9.
10.