全文获取类型
收费全文 | 652篇 |
免费 | 33篇 |
国内免费 | 234篇 |
出版年
2023年 | 1篇 |
2022年 | 1篇 |
2021年 | 5篇 |
2020年 | 30篇 |
2019年 | 24篇 |
2018年 | 5篇 |
2017年 | 6篇 |
2016年 | 25篇 |
2015年 | 47篇 |
2014年 | 20篇 |
2013年 | 53篇 |
2012年 | 26篇 |
2011年 | 14篇 |
2010年 | 30篇 |
2009年 | 20篇 |
2008年 | 22篇 |
2007年 | 27篇 |
2006年 | 25篇 |
2005年 | 26篇 |
2004年 | 22篇 |
2003年 | 29篇 |
2002年 | 28篇 |
2001年 | 28篇 |
2000年 | 33篇 |
1999年 | 25篇 |
1998年 | 32篇 |
1997年 | 26篇 |
1996年 | 18篇 |
1995年 | 23篇 |
1994年 | 29篇 |
1993年 | 22篇 |
1992年 | 24篇 |
1991年 | 18篇 |
1990年 | 22篇 |
1989年 | 18篇 |
1988年 | 17篇 |
1987年 | 12篇 |
1986年 | 21篇 |
1985年 | 15篇 |
1984年 | 13篇 |
1983年 | 3篇 |
1982年 | 10篇 |
1981年 | 7篇 |
1980年 | 6篇 |
1979年 | 4篇 |
1978年 | 1篇 |
1977年 | 3篇 |
1974年 | 1篇 |
1972年 | 2篇 |
排序方式: 共有919条查询结果,搜索用时 154 毫秒
1.
Summary Between 3 Nov. 1983 and 9 Apr. 1984, six applications of fertiliser N (ammonium, nitrate or urea) were given to four autumn
sown (26 Oct. 1983)Vicia faba L cultivars, Banner Winter (BW) and Maris Beagle (MBg), cold tolerant cultivars normally sown in the autumn, and Herz Freya
(HF) and Maris Bead (MBd), cold sensitive cultivars more commonly sown in the spring. The effects of additional N were determined
by comparison with plants given zero-N (controls).
Application of N, regardless of form, had no effect on % emergence at the first sampling (15 Dec. 1983); >90% for BW, MBg
and HF, but only 40–60% for MBd. At this time the dry weight, carbon content and nitrogen content of all cultivars was approximately
20% less than that of the seed on planting. No more plants emerged after 15 Dec. 1983. Between 15 Dec. 1983 and 20 Feb. 1984,
all cultivars, regardless of N treatment, showed little change in dry weight, carbon content and nitrogen content but the
proportion of total plant dry weight, carbon content and nitrogen content in the cotyledons decreased while the proportions
in root, stem and leaf tissue increased. On 20 Feb. 1984 there were no N effects. All cultivars but especially BW and MBg,
showed progressive increases in dry weight, carbon content and nitrogen content during the period 20 Feb. 1984 to 8 May 1984.
Pooled results for all four cultivars indicated that on 8 May 1984, plants given ammonium and urea had a greater dry weight,
carbon content and nitrogen content than controls.
At harvest (1–3 Sep. 1984), BW and MBg outyielded (g dw seed m−2) HF and MBd. Pooled results for all cultivars indicated that application of N regardless of form gave increased yield and
an increased N concentration (mg N g−1 dw) in the seed. 相似文献
2.
3.
D. L. Zhang K. Q. Li W. Gu L. F. Hao 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1987,75(1):132-137
Summary Different phytohormone concentrations induced different fequencies of various chromosome aberrations in calli of Vicia faba. NAA 10 ppm plus KT 2.5 ppm produced more haploids and NAA 30 ppm plus NAA 7.5 ppm produced more tetraploids and breakage. The relationship among the aberrations was analyzed. The hypothesis of ploidy equilibrium was established. The chromosome doubling rate and reduction rate of each treated group were calculated in relation to the observed data and the hypothesis. The frequency of tetraploids and breakage are correlated with each other. The frequency of total aberrations is linearly correlated with that of micronucleus formation. The regression equation is x=31.92+ 10.67 y. 相似文献
4.
On binding toVicia faba lectin, the fluorescence of 4-methylumbelliferyl-α-D-glucoPyranoside was quantitatively quenched showing that the interaction
of 4-methylumbelliferyl-α-D-glucoPyranoside took Place in a binding environment. The binding of the fluorescent sugar was
saccharide sPecific as evidenced by the reversal of 4-methylumbelliferyl-α-D-glucoPyranoside fluorescence quenching by D-fructose.
The association constant,K
a, values for the 4-methylumbelliferyl-α-D-glucoPyranoside was determined by comPetition study emPloying reversal of fluorescence
quenching of 4-methylumbelliferyl-α-D-glucoPyranoside by D-fructose. TheK
a value obtained for D-fructose was 1.07 ±0.03 X 104 M-1 and for 4-methylumbelliferyl-α-D-glucoPyranoside was 1.60 ±0.05 X 104 M-1 at 15°C. TheK
a values of 2.51 ±0.06 X 104M-1, l.26 ±0.02 X 104 M-1 and 0.56 ±0.01 X 104M-1, resPectively at 10°, 20° and 30°C were obtained from the ChiPman equation. The relative fluorescence quenching, ΔF
a, at infinite concentration of the free saccharide sites ofVicia faba lectin [P′] was 93.5% at 30°C and the binding constant for 4-methylumbelliferyl-α-D-glucoPyranoside lectin interaction as derived by
Yank and Hanaguchi equation was 0.63 ±0.01 X 104M-1. 相似文献
5.
王新宇 《Acta Botanica Sinica》1987,(3)
采用聚丙烯酰胺凝胶电泳技术分析了黑麦、蚕豆和百合花粉母细胞内肌动蛋白的存在与动态,结果表明高等植物的花粉母细胞在细胞融合期内的确存在一定量的肌动蛋白,并且,这种蛋白在早偶线期时出现,到四分体时期后消失。文章讨论了肌动蛋白的存在及其与细胞融合现象的联系。 相似文献
6.
R. Mancini C. De Pace G. T. Scarascia Mugnozza V. Delre D. Vittori 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1989,77(5):657-667
Summary This study was conducted to assess the genetic basis of the variability observed for the glutamate oxaloacetate transaminase (GOT), Superoxide dismutase (SOD), esterase (EST), and malate dehydrogenase (MDH) isozyme systems in different open-pollinated Vicia faba varieties. Individual plants showing contrasting zymogram patterns were simultaneously selfed and cross-combined. Crossing was unsuccessful in producing progeny, and only selfed progenies were suitable for genetical analysis of isozyme variability. Three zones of GOT activity were made visible. The isozyme of GOT-2 and GOT-3 zones were dimeric and under the control of three alleles at the Got-2 locus and two alleles at the Got-3 locus, respectively. The isozymes of the GOT-1 zone did not show any variability. Three zones of SOD isozyme activity were made visible. The isozymes occurring in the SOD-1 (chloroplastic isozyme form) and SOD-2 (cytosol isozyme form) zones were dimeric and under the control of two alleles at the Sod-1 and Sod-2 loci. The isozyme visualized in the SOD-3 zone (mitochondrial isozyme form) were tetrameric and under the control of two alleles at the Sod-3 locus. Apparently the isozymes made visible in the most anodal esterase zones EST-1, EST-2, and EST-3 were monomeric, and the occurrence of two alleles at each of two different loci explained the variability observed in the EST-2 and EST-3 zones. For MDH, only two five-banded zymogram pattern types were found, and every selfed progeny showed only one of the two zymogram type, indicating that each individual possessed fixed alleles at the loci controlling MDH isozyme. Got-2, Got-3, Sod-1, Sod-2, and Sod-3 appear to be five new isozyme gene markers that can be useful in Vicia faba breeding for linkage study, varietal fingerprinting, outcrossing rate estimate, and indirect selection for quantitative characters. 相似文献
7.
Abscission probability varies among floral positions within inflorescences of Vicia faba L. Flowers from proximal positions have a greater chance to develop into mature pods than flowers from more distal positions which normally abscise either as older flowers or as young pods. In three field experiments with the indeterminate single stem variety Herz-Freya, changes in the contents of extractable auxins, abscisic acid (ABA) and gibberellins in flowers and pods during their development, and their possible influence on abscission were investigated.Inflorescences at different positions along the stem were divided into the two proximal and the remaining fruits. The content of all three hormones was at a low level during flower development, increased greatly in parallel with dry matter accumulation in the young pods, and then decreased to maturity. The first hormone to increase in the fruits was auxin and this took place when abscission from the distal positions began. ABA and gibberellins at this time were still at a low level. This ontogenic course of hormone production was very similar in fruits of both positions within an inflorescence, but in flowers and young pods from proximal positions, auxin content in most inflorescences was greater than in those from the abscising distal positions. No such positional differences were observed with ABA and gibberellins. Decapitation of the plants reduced flower and pod drop from the remaining reproductive nodes. Although decapitation resulted in less abscission among distal flowers and young pods from these nodes, it did not affect the ontogenic course of auxin and ABA production in these fruits. 相似文献
8.
Plasmalemma-rich microsomal vesicles were prepared from whole leaf and acid-washed epidermal tissue of Vicia faba L. cv. Osnabrücker Markt by aqueous two-phase partitioning in dextran T-500 and polyethylenglycol 1350 aqueous phases. These vesicles were tightly sealed and predominantly right-side out, and contained a K+ -stimulated, mg2+-dependent and vanadate-sensitive ATPase. The enzyme from both tissues exhibited nearly identical properties: pH optimum 6.4, Km for ATP 0.60 mM(whole leaf) and 0.67 mM (epidermis). Vmax -480 nmol (mg protein)1 min1 (whole leaf) and 510 nmol (mg protein)1 min1 (epidermis), I50 (Na3,VO4) 7.5 μM (whole leaf) and 15 μM (epidermis). The enzyme was not inhibited by NO3(50 mM)or sodium azide (I mM). DCCD (20 μM) reduced enzyme activity to 50% (whole leaf) and 58% (epidermis), gramicidin S (20 μM) to 36% (whole leaf) and 41%(epidermis). Ca2+ inhibited the ATPase [I50, C2+: 0.5 mM(whole leaf) and 0.8 mM(epidermis)]. Ca2+ inhibited the ATPase [I50, C2+ 0.5 mM(whole leaf) und 0.8 (epidermis)]. The vanadate-sensitive ATPase from whole leaf and epidermal tissue was slightly but significantly stimulated by fusicoccin (FC) at a concentration (0.13 μM) promoting stomatal opening. The stimulation was not seen in the solubilized ATPase. Stomata of the cultivar used here were insensitive lo (±)ABA up to 2 μM level which is effective in most other cultivars and species. Likewise, at this concentration no effect of ABA on the activity of the epidermal ATPase was observed. The data are discussed with respect to the interaction of FC and ABA with the ATPase. 相似文献
9.
Before starting a breeding program aimed at improving the nitrogen nutrition ofVicia faba, the authors tried an alternative technique to the acetylene reduction assay, to measure some genetic variability in the
plant material. The quantity of dinitrogen fixed by several cultivars ofVicia faba was estimated using a low enrichment15N tracer method and high precision15N mass spectrometry. The fababeans were cultivated for two years in two different soils.
The percentage of fixed dinitrogen in the seed varied between genotypes from 40 to 83% of the total nitrogen and was positively
correlated with the total seed nitrogen (r=0.64 to 0.86). A highly significant positive correlation was also found between
the total seed nitrogen and the quantity of fixed dinitrogen in the seed (r=0.95 to 0.99).
The technique used to measure dinitrogen fixation proved to be useful and reliable enough to discriminate between various
genotypes, grown over a period of two years in two different soils. However, several non-fixing control plants showed significant
differences in their15N enrichment and the problem of choosing a good reference plant was raised and discussed. 相似文献
10.