全文获取类型
收费全文 | 2911篇 |
免费 | 251篇 |
国内免费 | 1篇 |
出版年
2023年 | 12篇 |
2022年 | 38篇 |
2021年 | 77篇 |
2020年 | 50篇 |
2019年 | 51篇 |
2018年 | 88篇 |
2017年 | 72篇 |
2016年 | 89篇 |
2015年 | 120篇 |
2014年 | 157篇 |
2013年 | 189篇 |
2012年 | 214篇 |
2011年 | 224篇 |
2010年 | 132篇 |
2009年 | 117篇 |
2008年 | 134篇 |
2007年 | 130篇 |
2006年 | 142篇 |
2005年 | 105篇 |
2004年 | 106篇 |
2003年 | 73篇 |
2002年 | 66篇 |
2001年 | 58篇 |
2000年 | 44篇 |
1999年 | 46篇 |
1998年 | 21篇 |
1997年 | 33篇 |
1996年 | 22篇 |
1995年 | 26篇 |
1994年 | 12篇 |
1992年 | 32篇 |
1991年 | 37篇 |
1990年 | 29篇 |
1989年 | 24篇 |
1988年 | 25篇 |
1987年 | 20篇 |
1986年 | 19篇 |
1985年 | 26篇 |
1984年 | 22篇 |
1983年 | 19篇 |
1982年 | 27篇 |
1981年 | 13篇 |
1980年 | 21篇 |
1979年 | 17篇 |
1977年 | 22篇 |
1974年 | 17篇 |
1973年 | 18篇 |
1972年 | 17篇 |
1970年 | 16篇 |
1967年 | 12篇 |
排序方式: 共有3163条查询结果,搜索用时 15 毫秒
11.
Jyotsana Prakash Rakesh Sharma Subhasree Ray Shikha Koul Vipin Chandra Kalia 《Indian journal of microbiology》2018,58(2):127-137
Wastewaters are a rich source of nutrients for microorganisms. However, if left unattended the biodegradation may lead to severe environmental hazards. The wastewaters can thus be utilized for the production of various value added products including bioenergy (H2 and CH4). A number of studies have reported utilization of various wastewaters for energy production. Depending on the nature of the wastewater, different reactor configurations, wastewater and inoculum pretreatments, co-substrate utilizations along with other process parameters have been studied for efficient product formation. Only a few studies have reported sequential utilization of wastewaters for H2 and CH4 production despite its huge potential for complete waste degradation. 相似文献
12.
Zinc Deficiency and Anther Development in Maize 总被引:1,自引:0,他引:1
Sharma Parma Nand; Chatterjee Chitralekha; Sharma Chandra Prakash; Agarwala Shirish Chandra 《Plant & cell physiology》1987,28(1):11-18
With the onset of male reproductive phase at 28 days, zinc waswithdrawn from fifty percent of maize (Zea mays L. cv. Ganga2) plants grown in refined sand at 0.13 mg Zn liter1.Plants from which zinc was withdrawn developed zinc deficiencysymptoms in young leaves after 38 days and were low in tissuezinc. Their tassel formation and pollen development was retarded.Anthers failed to develop beyond freshly liberated young pollengrain stage and vessels were formed in place of sporogenoustissue in sixty percent anthers of the younger of the two florets.Anthers from these plants showed low zinc concentration andstimulated specific activities of catalase, peroxidase, ribonucleaseand acid phosphatase. On resuming normal zinc (0.13 mg Zn liter1) through rootsto the plants from which it was withdrawn for 17 days, vegetativegrowth was partially renewed and short axillary buds were formedbut the development of anthers remained retarded. (Received April 11, 1986; Accepted October 15, 1986) 相似文献
13.
14.
Dr. Suvendra Nath Bagchi Paramjeet Kaloya Prakash Singh Bisen 《Current microbiology》1987,15(2):61-65
The control operative on the nitrate reductase enzyme system of host cyanobacteriumNostoc muscorum was studied after being infected with the cyanophage N-1. Phage infection lifted the host nitrate reductase activity level via accelerating the enzyme synthesis. It was found that the phage-mediated increase in the molybdenum cofactor synthesis was a major contributing factor for apparent elevated nitrate reductase level of the host. This process was inhibited in the presence of erythromycin and tungsten, the inhibitors of protein synthesis and new nitrate reductase synthesis respectively. While the preformed nitrate reductase of healthy cyanobacterium was inhibited by hydrogen peroxide, an oxidizing photosynthetic product, the same enzyme of infected cells remained virtually insensitive to this inhibitor. These data suggest involvement of new nitrate reductase synthesis and its resistance to oxidative inactivation as joint factors controlling the characteristic high enzyme level of host cyanobacterium. 相似文献
15.
16.
Two eriophyid mites,Acaphylla theae andCalacarus carinatus, have been known for some time as important pests of tea. In recent years a third eriophyid,Acaphyllisa parindiae, has also become abundant. The vertical distribution of these three species on tea is examined. 相似文献
17.
Data on the physico-chemical properties of proteins from soybean, groundnut, sesame seed, sunflower seed, safflower seed,
mustard seed, rapeseed and cotton seed are fairly extensive. An examination of the available data on high molecular weight
proteins suggests that there are similarities in many of their properties. In this report the similarity in amino acid composition,
size and shape, molecular weight, secondary structure, subunit composition, association-dissociation at high and low pH, stability
towards denaturants, hydrolysis by enzymes and quaternary structure of the high molecular weight proteins is discussed. Based
on these similarities a model has been proposed for the associationdissociation, denaturation and reassociation behaviour
of the high molecular weight proteins of oilseeds. 相似文献
18.
Summary Soybean plants were grown in pots with or without vesicular-arbuscular myocorrhizal (VAM) fungi in three soils of low plant-available
P content, different texture and different water-holding capacities. Mineral nutrients, except P, were provided in a complete
nutrient solution. The biomass of non-VAM plants was positively and fungal colonization negatively correlated with increasingly
coarse soil texture. There was no correlation of soil P with host or endophyte growth. Plant growth enhancement was positively
correlated with soil water content at −1.5 MPa. These observations suggest soil water status and the mycorrhizal condition
interact in influencing plant growth. 相似文献
19.
Molecular cloning and expression of Rhizobium fredii USDA 193 nodulation genes: extension of host range for nodulation. 总被引:6,自引:3,他引:3
下载免费PDF全文
![点击此处可从《Journal of bacteriology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
N Ramakrishnan R K Prakash S Shantharam N M Duteau A G Atherly 《Journal of bacteriology》1986,168(3):1087-1095
DNA hybridization with the cloned nodulation region of Rhizobium meliloti as a probe revealed DNA homology with four HindIII fragments, 12.5, 6.8, 5.2, and 0.3 kilobases (kb) in size, of the symbiotic plasmid pRjaUSDA193. Both hybridization and complementation studies suggest that the common nodulation genes nodABC and nodD of R. fredii USDA 193 are present on the 5.2-kb HindIII and 2.8-kb EcoRI fragments, respectively, of the Sym plasmid. Both fragments together could confer nodulation ability on soybeans when present in Sym plasmid-cured (Sym-) and wild-type (Sym+) Rhizobium strains or in a Ti plasmid-cured Agrobacterium tumefaciens strain. Furthermore, the 2.8-kb EcoRI fragment alone was able to form nodulelike structures on Glycine max L. cv. "Peking" (soybean). Microscopic examination of these nodules revealed bacterial invasion of the cells, probably via root hair penetration. Bacterial strains harboring plasmids carrying the 5.2- and 2.8-kb nod fragments elicited root-hair-curling responses on infection. These data suggest that the genes responsible for host range determination and some of the early events of nodulation may be coded for by the 5.2-kb HindIII and 2.8-kb EcoRI fragments. 相似文献
20.