全文获取类型
收费全文 | 1522篇 |
免费 | 70篇 |
国内免费 | 1篇 |
出版年
2024年 | 5篇 |
2023年 | 20篇 |
2022年 | 50篇 |
2021年 | 77篇 |
2020年 | 52篇 |
2019年 | 67篇 |
2018年 | 60篇 |
2017年 | 65篇 |
2016年 | 91篇 |
2015年 | 123篇 |
2014年 | 119篇 |
2013年 | 173篇 |
2012年 | 152篇 |
2011年 | 125篇 |
2010年 | 66篇 |
2009年 | 47篇 |
2008年 | 38篇 |
2007年 | 37篇 |
2006年 | 39篇 |
2005年 | 28篇 |
2004年 | 24篇 |
2003年 | 20篇 |
2002年 | 12篇 |
2001年 | 8篇 |
2000年 | 7篇 |
1999年 | 5篇 |
1998年 | 6篇 |
1997年 | 3篇 |
1996年 | 10篇 |
1995年 | 3篇 |
1994年 | 5篇 |
1993年 | 7篇 |
1992年 | 4篇 |
1990年 | 1篇 |
1989年 | 3篇 |
1988年 | 4篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1984年 | 6篇 |
1982年 | 4篇 |
1981年 | 3篇 |
1980年 | 4篇 |
1979年 | 1篇 |
1978年 | 3篇 |
1977年 | 1篇 |
1976年 | 3篇 |
1975年 | 1篇 |
1974年 | 2篇 |
1973年 | 4篇 |
排序方式: 共有1593条查询结果,搜索用时 15 毫秒
1.
2.
Isolation and screening of potential actinobacteria for rapid composting of rice straw 总被引:2,自引:0,他引:2
Rice straw is produced as a by-product from rice cultivation, which is composed largely of lignocellulosic materials amenable
to general biodegradation. Lignocellulolytic actinobacteria can be used as a potential agent for rapid composting of bulky
rice straw. Twenty-five actinobacteria isolates were isolated from various in situ and in vitro rice straw compost sources.
Isolates A2, A4, A7, A9 and A24 were selected through enzymatic degradation of starch, cellulose and lignin followed by the
screening for their adaptability on rice straw powder amended media. The best adapted isolate (A7) was identified as Micromonospora
carbonacea. It was able to degrade cellulose, hemicelluloses and carbon significantly (P ≤ 0.05) over the control. C/N ratio was reduced to 18.1 from an initial value of 29.3 in 6 weeks of composting thus having
the potential to be used in large scale composting of rice straw. 相似文献
3.
4.
Salt tolerance ofEchinochloa crusgalli was studied using gravel culture with root medium electrical conductivity between 3 to 25 dS m-1. Salinity depressed germination and shoot yield. A 50 % reduction in shoot yield occurred at 15.9 dS m-1. The plant was able to maintain its tissue water content and K concentration in the tissue water while Na, Ca and Cl increased
and Mg decreased with increasing root zone salinity. 相似文献
5.
Effects of tissue position (viz. outer vs inner mesocarp) and heat treatment (48°C, 20 min) on variations in polygalacturonase (EC 3.2.1.15 and EC 3.2.1.67) activity and ripening of fruits of Carica papaya L. cv. Backcross Solo were investigated. Polygalacturonase activity increased during ripening concomitantly with an increase in tissue softness and soluble polyuronide level. Throughout ripening, inner mesocarp tissue was softer and contained higher polygalacturonase activity than outer mesocarp tissue. Titratable acidity as well as ß-galactosidase (EC 3.2.1.23) activity also increased during ripening; however, unlike polygalacturonase, their level or activity was lower in inner than in outer mesocarp. Ascorbic acid could partially account for the increase in titratable acidity during ripening but contributed very little to the differences in titratable acid levels between outer and inner mesocarp. Heat treatment had no effect on either fruit softness or titratable acidity, but it markedly reduced the increase in ascorbic acid and polygalacturonase activity during ripening. Ripening, as reflected by changes in tissue softness and polygalacturonase activity, progressed outwardly from the interior towards the exterior of the fruit. The effect of heat treatment in suppressing polygalacturonase activity was relatively greater in inner than in outer mesocarp, suggesting that sensitivity of the enzyme to heat treatment may vary with stage of ripeness of the tissue. 相似文献
6.
Infection by Macrophonina phaseolina was substantially reduced following treatment of sunflower and mungbean seeds with Trichoderma harzianum, Gliocladium virens, Paecilomyces lilacinus or Streptomyces sp. which gave promising control of charcoal rot disease. Treatment of mungbean seeds with Rhizobium meliloti also gave good disease control. 相似文献
7.
This study reports the effect of salinity and inoculation on growth, ion uptake and nitrogen fixation byVigna radiata. A soil ECe level of 7.5 dS m−1 was quite detrimental causing about 60% decline in dry matter and grain yield of mungbean plants whereas a soil ECe level of 10.0 dS m−1 was almost toxic. In contrast most of the studied strains of Rhizobium were salt tolerant. Nevertheless, nodulation, nitrogen
fixation and total nitrogen concentration in the plant was drastically affected at high salt concentration. A noticeable decline
in acetylene reduction activity occurred when salinity level increased to 7.5 dS m−1. 相似文献
8.
Ravigadevi Sambanthamurthi Siti Hasnah Parman Mohd. Roslan Md. Noor 《Plant Cell, Tissue and Organ Culture》1996,46(1):35-41
Procedures are deseribed for the efficient isolation of protoplasts from a variety of oil palm (Elaeis guineensis Jacq.) tissues. Various factors including donor source, composition of enzyme mixture and culture medium affected the yield and viability of the protoplasts Polyembryogenic cultures of oil palm were the most suitable starting material in terms of yield, viability and metabolic competence. Pectolyase Y-23 in association with cellulase and hemicellulase was required for the efficient release of protoplasts from the oil palm tissues. Limited cell division to form microcallus was observed at very low frequency (<0.01%) when glutathione and catalase were incorporated in the culture medium.Abbreviations 2,4-d
dichlorophenoxyacetic acid
- DTT
dithiothreitol
- MES
2[N-morpholino] ethanesulphonic acid
- NAA
1-naphthalene acetic acid
- PVP
polyvinylpyrrolidone 相似文献
9.
The effect of NH
4
+
on the regulation of NO
3
–
and NO
2
–
transport systems in roots of intact barley (Hordeum vulgareL.) seedlings grown in NO
3
–
or NO
2
–
was studied. Ammonium partially inhibited induction of both transport systems. The inhibition was less severe in NO
2
–
-fed than in NO
3
–
-fed seedlings, presumably due to lower uptake of NH
4
+
in the presence of NO
2
–
. In seedlings pretreated with NH
4
+
subsequent induction was inhibited only when NH
4
+
was also present during induction, even though pretreated roots accumulated high levels of NH
4
+
. This indicates that inhibition may be regulated by NH
4
+
concentration in the cytoplasm rather than its total accumulation in roots. L-Methionine sulfoximine did not relieve the inhibition by NH
4
+
, suggesting that inhibition is caused by NH
4
+
itself rather than by its assimilation product(s). Ammonium inhibited subsequent expression of NO
3
–
transport activity similarly in roots grown in 0.1, 1.0, or 10 mM NO
3
–
for 24 h (steady-state phase) or 4 d (decline phase), indicating that it has a direct, rather than general feedback effect. Induction of the NO
3
–
transport system was about twice as sensitive to NH
4
+
as compared to the NO
2
–
transport system. This may relate to higher turnover rates of membraneassociated NO
3
–
-transport proteins.Abbreviations Mes
2(N-morpholino)ethanesulfonic acid
- MSO
L-methionine sulfoximine 相似文献
10.
The endoplasmic reticulum (ER) membrane protein complex (EMC) is essential for the insertion of a wide variety of transmembrane proteins into the plasma membrane across cell types. Each EMC is composed of Emc1-7, Emc10, and either Emc8 or Emc9. Recent human genetics studies have implicated variants in EMC genes as the basis for a group of human congenital diseases. The patient phenotypes are varied but appear to affect a subset of tissues more prominently than others. Namely, craniofacial development seems to be commonly affected. We previously developed an array of assays in Xenopus tropicalis to assess the effects of emc1 depletion on the neural crest, craniofacial cartilage, and neuromuscular function. We sought to extend this approach to additional EMC components identified in patients with congenital malformations. Through this approach, we determine that EMC9 and EMC10 are important for neural crest development and the development of craniofacial structures. The phenotypes observed in patients and our Xenopus model phenotypes similar to EMC1 loss of function likely due to a similar mechanism of dysfunction in transmembrane protein topogenesis. 相似文献