全文获取类型
收费全文 | 161篇 |
免费 | 16篇 |
国内免费 | 17篇 |
出版年
2023年 | 3篇 |
2022年 | 2篇 |
2021年 | 6篇 |
2020年 | 3篇 |
2019年 | 2篇 |
2017年 | 1篇 |
2016年 | 6篇 |
2015年 | 4篇 |
2014年 | 6篇 |
2013年 | 7篇 |
2012年 | 11篇 |
2011年 | 12篇 |
2010年 | 11篇 |
2009年 | 11篇 |
2008年 | 5篇 |
2007年 | 9篇 |
2006年 | 3篇 |
2005年 | 12篇 |
2004年 | 1篇 |
2003年 | 8篇 |
2002年 | 3篇 |
2001年 | 4篇 |
2000年 | 6篇 |
1999年 | 4篇 |
1998年 | 7篇 |
1997年 | 3篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1989年 | 4篇 |
1988年 | 3篇 |
1987年 | 1篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1978年 | 2篇 |
1977年 | 4篇 |
1976年 | 2篇 |
1972年 | 3篇 |
1971年 | 1篇 |
1969年 | 1篇 |
1968年 | 2篇 |
1967年 | 1篇 |
1966年 | 1篇 |
排序方式: 共有194条查询结果,搜索用时 437 毫秒
161.
In etiolated pea and maize leaves illuminated after incubation at 38 degreesC, a new dark reaction was shown manifested in the bathochromic shift of spectral bands and accompanied by esterification of the product of protochlorophyllide photochemical reduction--Chld 684/676: Chld 684/676 --> Chl 688/680. After completion of the reaction a rapid (20-30 sec) quenching of the fluorescence of the reaction product (Chl 688/680) was observed. The reaction Chld 684/676 --> Chl 688/680 is inhibited under anaerobic conditions and in the presence of cyanide; the reaction accompanied by Chl 688/680 fluorescence quenching is not observed in pea mutants with impaired function of photosystem II reaction centers. The spectral properties of the formed Chl form with the absorption maximum at 680 nm, fluorescence quenching, and simultaneous synthesis of pheophytin suggest that the reaction is connected with the chlorophyll of photosystem II reaction center--P-680. 相似文献
162.
Phosphate Regulation of Nitrate Assimilation in Soybean 总被引:24,自引:1,他引:23
RUFTY THOMAS W. JR; ISRAEL DANIEL W.; VOLK RICHARD J.; QIU JINSHU; SA TONGMIN 《Journal of experimental botany》1993,44(5):879-891
It is known that phosphorus deficiency results in alterationsin the assimilation of nitrogen. An experiment was conductedto investigate mechanisms involved in altered 15NO3 uptake,endogenous 15N translocation, and amino acid accumulation insoybean (Glycine max L. Merrill, cv. Ransom) plants deprivedof an external phosphorus supply for 20 d in solution culture.Phosphorus deprivation led to decreased rates of 15NO3uptake and increased accumulation of absorbed 15N in the root.Both effects became more pronounced with time. Asparagine, theprimary transport amino acid in soybean, accumulated in largeexcess in roots and stems. In roots of phosphorus-deprived plants,concentrations of ATP and inorganic phosphate declined rapidly,but dry weight accumulation was similar to or above that ofthe control even after 20 d of treatment. Arginine accumulationin leaves was greatly enhanced, even though 15N partitioninginto the insoluble reduced-N fraction of leaves was unaffected.The results suggest that decreases in NO3 uptake in lowphosphorus plants could be caused by feedback control factorsand by limited ATP availability. The decline in endogenous Ntransport from the root to the shoot may be associated withchanges in membrane properties, which also result in paralleleffects on hydraulic conductance and the upward flow of waterthrough the plant. Key words: Phosphorus stress, nitrate uptake, nitrate translocation, arginine 相似文献
163.
PCR-based assays of mendelian polymorphisms from anonymous single-copy nuclear DNA: techniques and applications for population genetics 总被引:5,自引:0,他引:5
This paper outlines a PCR-based approach for population genetics that
offers several advantages over conventional Southern blotting methods for
revealing restriction-fragment-length polymorphisms (RFLPs) in nuclear DNA.
Primers are constructed from clones isolated from a nuclear DNA library,
and these primers subsequently are employed in in vitro syntheses of
homologous regions. Amplified products are then screened directly for RFLPs
by using gel-staining procedures. Population applications for this
PCR-based approach, including potential strengths and weaknesses, are
exemplified by two RFLP data sets generated to estimate (a) male-mediated
gene flow in the green turtle (Chelonia mydas) and (b) geographic
population genetic structure in the American oyster (Crassostrea
virginica). Restriction assays of amplified products from 14 or 15
independent primer pairs in each species revealed polymorphisms at several
loci that proved highly informative in the population genetic analyses. In
general, the Mendelian polymorphisms produced by this PCR-based approach
will provide useful genetic markers for population studies, particularly in
situations where simpler and less expensive allozyme methods have failed,
for whatever reason, to provide adequate information.
相似文献
164.
165.
166.
Background
The first microbial genome sequence, Haemophilus influenzae, was published in 1995. Since then, more than 400 microbial genome sequences have been completed or commenced. This massive influx of data provides the opportunity to obtain biological insights through comparative genomics. However few tools are available for this scale of comparative analysis. 相似文献167.
Background
The analysis of biological data is greatly enhanced by existing or emerging databases. Most existing databases, with few exceptions are not designed to easily support large scale computational analysis, but rather offer exclusively a web interface to the resource. We have recognized the growing need for a database which can be used successfully as a backend to computational analysis tools and pipelines. Such database should be sufficiently versatile to allow easy system integration. 相似文献168.
Chumachenko SS Tarasov IuA Pron'ko PS Bardina LP Satanovskaia VI 《Rossi?skii fiziologicheski? zhurnal imeni I.M. Sechenova / Rossi?skaia akademiia nauk》2005,91(8):903-909
The effect of single and chronic ethanol (Eth) administration (25 % solution, 3.5 g/kg) on functional activity of the hypophyseal-adrenal system in rats with different sensitivity to the hypnotic action of ethanol (short-sleep - SS; non-sleep--NS, long-sleep--LS, intermediate group--IG), was studied. It has been shown that, after a single Eth administration, the concentration of corticosterone (K) in LS rat plasma was 1.5-fold higher than that in the NS animals although it did not differ from the K level in SS and Ig those. After repeated ethanol load, the corticosterone contents in the NS rat blood plasma was 3.5-fold and 4.9-fold lower compared to the control and LS groups, respectively. The data obtained indicate that the SS and LS animals had initially different basal blood plasma glucocorticoid level. The SS animals showed a decreased blood plasma K, whereas the LS ones--an increased one. The features of the glucocorticoid status are suggested to be a factor determining the sensitivity of rats to the ethanol hypnotic effect. 相似文献
169.
Tarasov IuA Sheĭbak VM Chumachenko SS Lelevich VV 《Rossi?skii fiziologicheski? zhurnal imeni I.M. Sechenova / Rossi?skaia akademiia nauk》2005,91(8):910-914
The data are presented on the effects of ethanol treatment (3.5 g/kg of a 25 % solution, singly, daily, intraperitoneally for 1, 4, 7, 10 days) on development of tolerance to ethanol as assessed by changes in ethanol-induced sleep, corticosterone level dynamics and free aminoacis content in rat blood plasma. 相似文献
170.