全文获取类型
收费全文 | 606篇 |
免费 | 49篇 |
出版年
2023年 | 5篇 |
2022年 | 12篇 |
2021年 | 30篇 |
2020年 | 12篇 |
2019年 | 17篇 |
2018年 | 32篇 |
2017年 | 21篇 |
2016年 | 23篇 |
2015年 | 38篇 |
2014年 | 33篇 |
2013年 | 47篇 |
2012年 | 42篇 |
2011年 | 35篇 |
2010年 | 28篇 |
2009年 | 28篇 |
2008年 | 21篇 |
2007年 | 29篇 |
2006年 | 29篇 |
2005年 | 18篇 |
2004年 | 21篇 |
2003年 | 14篇 |
2002年 | 19篇 |
2001年 | 9篇 |
2000年 | 7篇 |
1999年 | 7篇 |
1998年 | 4篇 |
1997年 | 3篇 |
1996年 | 2篇 |
1995年 | 3篇 |
1994年 | 4篇 |
1993年 | 3篇 |
1992年 | 4篇 |
1991年 | 4篇 |
1990年 | 4篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1986年 | 4篇 |
1983年 | 4篇 |
1980年 | 6篇 |
1979年 | 8篇 |
1977年 | 2篇 |
1976年 | 3篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1969年 | 1篇 |
1968年 | 1篇 |
1966年 | 2篇 |
1965年 | 2篇 |
1963年 | 1篇 |
排序方式: 共有655条查询结果,搜索用时 31 毫秒
81.
Improving vanadium stress tolerance of watermelon by grafting onto bottle gourd and pumpkin rootstock 总被引:1,自引:0,他引:1
Muhammad Azher Nawaz Chen Chen Fareeha Shireen Zhuhua Zheng Yanyan Jiao Hamza Sohail Muhammad Afzal Muhammad Imtiaz Muhammad Amjad Ali Yuan Huang Zhilong Bie 《Plant Growth Regulation》2018,85(1):41-56
Vanadium (V) is a transition metal found in the Earth crust. V adversely affects plant growth and development. Besides several other management practices, grafting of scion cultivars onto appropriate rootstock provides a suitable solution. Grafting is an important agro-technical procedure utilized to enhance the capacity of plants to tolerate biotic and abiotic stresses. In this study, watermelon was grafted onto bottle gourd and pumpkin rootstock, and self-grafted watermelon plants were utilized as a control. V was applied at the rate of 50 mg/L under hydroponic conditions. The result showed that V application substantially reduces the growth of watermelon plants, however, grafting of watermelon onto bottle gourd and pumpkin rootstock improves V stress tolerance of watermelon by reducing the V concentration in leaf tissues, improving the relative chlorophyll content (SPAD index) and photosynthetic assimilation, up-regulating the expression of SOD (Cla008698, Cla0012125, Cla009820 and Cla001158), glutathione S-transferase (Cla013224) and glutathione peroxidase (Cla021039) genes in the leaves, and enhancing the activities of antioxidant enzymes (SOD, CAT). The scanning electron microscopy (SEM) of the root tips showed that minimal damage of roots was observed for pumpkin roots compared with the roots of watermelon and bottle gourd under V stress conditions. So far as we know, these results are the first evidence that grafting mitigates V stress in plants. 相似文献
82.
Ali Noman Qasim Ali Jazia Naseem M. Tariq Javed Hina Kanwal Waqar Islam Muhammad Aqeel Noreen Khalid Sara Zafar Muhammad Tayyeb Naeem Iqbal Mahmooda Buriro Junaid Maqsood Samreena Shahid 《Acta Physiologiae Plantarum》2018,40(6):110
The present study investigated the role of sugar beet extract (SBE) as a bio-stimulant to ameliorate the adverse effects of drought on seed germination and growth of wheat (Triticum aestivum L.). Different concentrations of SBE (0, 10, 20, 30, 40 and 50%) were used for priming the wheat seeds. The experiment was conducted in laboratory (PEG-8000 was used to create water stress) as well as under natural environmental conditions (using soil with 100 and 60% field capacity). Significant ameliorating effects of seed priming with SBE were recorded on different germination attributes, i.e., time to 50% emergence (E50), germination index (GI), mean emergence time (MET), germination percentage (G%), coefficient of uniformity of emergence (CUE) and germination energy (GE) under water stress. Without priming, the plants exhibited symptoms of water stress like decreased biomass, reduction in photosynthetic pigments, e.g., chlorophyll, carotenoids. Seed pre-conditioning with SBE improved the plant growth, photosynthetic pigments, antioxidants’ activities and nutrient homeostasis of plants facing water deficit and grown under well-watered conditions. The maximum increase in biomass, content of chlorophyll, carotenoids and activities of superoxide dismutase (SOD) and peroxidase (POD) was 13.4, 8.5, 11.9, 7.6, 13.6, 42.0, 19.8%, respectively, with SBE seed priming under water stress. In conclusion, SBE seed priming effectively reduced the negativities of water stress on seed germination which resulted in better plant growth in terms of enhanced biomass, photosynthetic pigments, antioxidant defense mechanism and better nutrient homeostasis. Overall, the findings suggest that seed pre-conditioning with SBE as a bio-stimulant will be helpful for better crop stand establishment under low field capacity, especially in semi-arid and arid agricultural fields. 相似文献
83.
84.
85.
Chemical and isotopic changes in plant biochemicals that were transformed into organic geochemicals have been measured in
anaerobic, freshwater marsh environments. In two litter bag studies, plant biochemicals decayed extensively in the first year,
as recorded by dry weight, C:N ratios, δ15N of bulk tissue and amino acids, and δ13C of individual amino acids. Molecular analyses of Rubisco revealed that the high-molecular-weight enzyme subunit could be
recognized antigenically for at least 12 months, but concentrations and amounts declined. Geochemical compounds, advanced
glycation endproducts, were not found in fresh plants, but formed gradually with first indications documented at 3 months.
The organic remains of plants were reworked or replaced by microbial products from decomposition, as indicated by a shift
in the isotopic composition of individual amino acids in total plant protein. In experiments with Rubisco, isotopic changes
over time in the individual amino acids in the 50–60 kDa molecular weight range were substantial. These high-molecular-weight
substances were no longer pristine molecules. Biochemical and isotopic tools for studying living processes have been demonstrated
to be effective and novel approaches to identify and quantify altered geochemical remnants.
Received: 1 July 1998 / Accepted: 15 March 1999 相似文献
86.
Neurovirulence tests in Macaca fascicularis using commercial preparations of different vaccine bulks and a wild-type strain revealed that the test was unable to distinguish mixed from pure populations or a suitable vaccine from a related strain which has been shown to be associated with clinical meningitis. However, the test was able to distinguish a wild-type strain from the vaccine strains successfully. The ability of the test to discriminate between acceptable and unacceptable seeds requires further examination. 相似文献
87.
Noreen Sheehya Bryan Markeya P.Joseph Quinna 《FEMS immunology and medical microbiology》1997,17(4):201-205
Partial 16S nucleotide sequences of Chlamydia psittaci isolates S26/3 (abortion), P94/1 (pigeon) and Chlamydia pecorum isolates W73 (enteric) and E58 (encephalomyelitis) were determined. Analysis of these data indicates very high levels of interspecies sequence conservation, with C. psittaci being more closely related to C. pecorum than to C. pneumoniae or C. trachomatis. Restriction enzyme analysis of nucleotide sequences indicated that BslI can be used to clearly distinguish C. psittaci and C. pecorum isolates. Psittacine and non-psittacine (pigeon) avian isolates of C. psittaci were distinguished using MaeI. 相似文献
88.
Small molecule drugs have readily been developed against many proteins in the human proteome, but RNA has remained an elusive target for drug discovery. Increasingly, we see that RNA, and to a lesser extent DNA elements, show a persistent tertiary structure responsible for many diverse and complex cellular functions. In this digest, we have summarized recent advances in screening approaches for RNA targets and outlined the discovery of novel, drug-like small molecules against RNA targets from various classes and therapeutic areas. The link of structure, function, and small-molecule Druggability validates now for the first time that RNA can be the targets of therapeutic agents. 相似文献
89.
Dodonaea viscosa, a wild and perennial shrub that can tolerate harsh environmental conditions, was used for the isolation of its endophytic bacteria and their potential was explored for the promotion of Canola growth. The bacteria identified through 16S rRNA gene sequencing, belonged to ten different genera namely Inquilinus, Xanthomonas, Pseudomonas, Rhizobium, Brevundimonas, Microbacterium, Bacillus, Streptomyces, Agrococcus and Stenotrophomonas. All the strains produced small amount of IAA (indole acetic acid) in the absence of tryptophan and comparatively more in the presence of tryptophan. All the bacterial strains were positive for ammonia production, cellulase and pectinase activity, but few of them showed phosphate solubilization, siderophore and hydrogen cyanide production. Only three strains showed ACC (1-aminocyclopropane-1-carboxylate) deaminase activity when tested using in-vitro enzyme assay. Members of genera Bacillus, Pseudomonas and Streptomyces showed positive chitinase, protease and antifungal activity against two phytopathogenic fungi Aspergillus niger and Fusarium oxysoprum, while members of Xanthomonas, Pseudomonas and Bacillus showed significant root elongation of Canola which could be related with their positive plant-growth-promoting (PGP) traits. Among the three plant growth promoting Bacillus strains, B. idriensis is never reported before for its PGP activities. These results showed the potential of Dodonaea viscosa endophytic bacteria as PGPBs, which in future can be further explored for their host range/molecular mechanisms. 相似文献
90.