全文获取类型
收费全文 | 3654篇 |
免费 | 184篇 |
国内免费 | 1篇 |
专业分类
3839篇 |
出版年
2023年 | 36篇 |
2022年 | 67篇 |
2021年 | 102篇 |
2020年 | 63篇 |
2019年 | 69篇 |
2018年 | 111篇 |
2017年 | 89篇 |
2016年 | 142篇 |
2015年 | 159篇 |
2014年 | 178篇 |
2013年 | 290篇 |
2012年 | 329篇 |
2011年 | 282篇 |
2010年 | 165篇 |
2009年 | 167篇 |
2008年 | 184篇 |
2007年 | 179篇 |
2006年 | 137篇 |
2005年 | 134篇 |
2004年 | 117篇 |
2003年 | 106篇 |
2002年 | 69篇 |
2001年 | 58篇 |
2000年 | 37篇 |
1999年 | 35篇 |
1998年 | 20篇 |
1997年 | 17篇 |
1996年 | 20篇 |
1995年 | 14篇 |
1994年 | 11篇 |
1993年 | 11篇 |
1992年 | 30篇 |
1991年 | 21篇 |
1990年 | 29篇 |
1989年 | 21篇 |
1988年 | 29篇 |
1987年 | 22篇 |
1986年 | 24篇 |
1985年 | 26篇 |
1984年 | 21篇 |
1983年 | 25篇 |
1982年 | 14篇 |
1981年 | 17篇 |
1979年 | 20篇 |
1978年 | 10篇 |
1977年 | 14篇 |
1974年 | 16篇 |
1972年 | 19篇 |
1971年 | 14篇 |
1969年 | 12篇 |
排序方式: 共有3839条查询结果,搜索用时 0 毫秒
71.
72.
Dalal Subhamita Adhikary Jayashree Roy Anup Biswas Shampa Sarkar Mukhopadhyay Prabir Kumar Acharya Sagar Ghosh Amlan 《Molecular biology reports》2022,49(9):8369-8380
Molecular Biology Reports - On the background of the epidemiological link between diabetes and oral cancer, the present study aimed to analyze the potential involvement of selected glucose... 相似文献
73.
A new species of the genus Cirrhimuraena (Anguilliformes: Ophichthidae) from the Bay of Bengal,India
Anil Mohapatra Swarup Ranjan Mohanty Dipanjan Ray Subhrendu Sekhar Mishra Jaya Kishor Seth 《Journal of fish biology》2021,98(5):1363-1370
A new species of the genus Cirrhimuraena (Anguilliformes: Ophichthidae), Cirrhimuraena indica sp. nov., is described based on eight specimens collected from the Paradip (Odisha) and Petuaghat harbours (West Bengal) along the Bay of Bengal. The species is distinct in having the upper jaw fringed with 16–17 cirri before posterior nostril and 4–5 in between the anterior and posterior nostrils on the side; dorsal fin originates above the level of gill opening, predorsal length is 9.3–10.9 in total length; the head is relatively large, the length is 9.3–9.8 in total length; no infraorbital pores are observed between the nostrils; teeth are numerous, small, conical and in bands on each jaw; pores are present before the gill opening 10–11 and before anus 47–48; pectoral-fin length is 2.4–2.8 in head length; predorsal vertebrae are 8–10, pre-anal vertebrae 43–47 and total vertebrae 164–169. In the maximum likelihood tree analysis for COI gene, the new species belongs to the same clade as the other congener of Cirrhimuraena chinensis and is separated from the species morphologically and genetically. 相似文献
74.
Lallan Mishra Vishnu ji Ram Saraswati Mishra 《Bioscience, biotechnology, and biochemistry》2013,77(8):2147-2148
A remarkable improvement in the emulsifying properties of proteins was observed in mixtures of serum albumin-dextran sulfate, lysozyme-dextran sulfate, serum albumin-chondroitin sulfate, α-lactalbumin-chondroitin sulfate and lysozyme-chondroitin sulfate. The emulsifying properties of these protein-polysaccharide complexes were affected by the molecular size of the polysaccharide and by such conditions as the presence of salt, acidic or alkaline pH, and heating. On the other hand, the emulsifying properties of ovalbumin-dextran hybrids prepared by covalent attachment were more enhanced in alkaline pH or by heating. The molecular size of the ovalbumin-dextran hybrids greatly affected the emulsifying properties. 相似文献
75.
76.
Selective inhibition of cell-free translation by oligonucleotides targeted to a mRNA hairpin structure. 下载免费PDF全文
Using an in vitro selection approach we have previously isolated oligodeoxy aptamers that can bind to a DNA hairpin structure without disrupting the double-stranded stem. We report here that these oligomers can bind to the RNA version of this hairpin, mostly through pairing with a designed 6 nt anchor. The part of the aptamer selected against the DNA hairpin did not increase stability of the RNA-aptamer complex. However, it contributed to the binding site for Escherichia coli RNase H, leading to very efficient cleavage of the target RNA. In addition, a 2'- O -methyloligoribonucleotide analogue of one selected sequence selectively blocked in vitro translation of luciferase in wheat germ extract by binding to the hairpin region inserted upstream of the initiation codon of the reporter gene. Therefore, non-complementary oligomers can exhibit antisense properties following hybridization with the target RNA. Our study also suggests that in vitro selection might provide a means to extend the repertoire of sequences that can be targetted by antisense oligonucleotides to structured RNA motifs of biological importance. 相似文献
77.
Glycine betaine relieved sodium chloride-mediated inhibition of growth in Azospirillum lipoferum ATCC 29708. 35S-methionine labelling of proteins after salinity up-shock revealed strong induction of a 30 kDa protein which cross-reacted with the anti-glycine betaine binding protein antibody from Escherichia coli. This suggested that A. lipoferum had a salinity-induced ProU-like high-affinity glycine betaine transport system. A genomic library of A. lipoferum ATCC 29708 was screened for the proU-like gene by complementation of a proU mutant of E. coli. Four recombinant cosmids, capable of restoring growth of the proU mutant on plates containing 600 mM NaCl and 1 mM glycine betaine were selected. Selected recombinant cosmids hybridized with a proU gene probe from E. coli. Complementation of E. coli proU mutant with the A. lipoferum genomic DNA was evident by the ability of proU mutant (containing selected recombinant cosmids) to grow on minimal medium supplemented with 600 mM NaCl and 1 mM glycine betaine. 相似文献
78.
79.
80.
Subash Chandra Gupta Hifzur Rahman Siddique Neeraj Mathur Achchhe Lal Vishwakarma Ranjit Kishore Mishra Daya Krishna Saxena Debapratim Kar Chowdhuri 《Biochimica et Biophysica Acta (BBA)/General Subjects》2007
We examined a hypothesis that reactive oxygen species (ROS) generated by organophosphate compound dichlorvos modulates Hsp70 expression and anti-oxidant defense enzymes and acts as a signaling molecule for apoptosis in the exposed organism. Dichlorvos (0.015–15.0 ppb) without or with inhibitors of Hsp70, superoxide dismutase (SOD) and catalase (CAT) were fed to the third instar larvae of Drosophila melanogaster transgenic for hsp70 (hsp70-lacZ) Bg9 to examine Hsp70 expression, oxidative stress and apoptotic markers. A concentration- and time-dependent significant increase in ROS generation accompanied by a significant upregulation of Hsp70 preceded changes in antioxidant defense enzyme activities and contents of glutathione, malondialdehyde and protein carbonyl in the treated organisms. An inhibitory effect on SOD and CAT activities significantly upregulated ROS generation and Hsp70 expression in the exposed organism while inhibition of Hsp70 significantly affected oxidative stress markers induced by the test chemical. A comparison made among ROS generation, Hsp70 expression and apoptotic markers showed that ROS generation is positively correlated with Hsp70 expression and apoptotic cell death end points indicating involvement of ROS in the overall adversity caused by the test chemical to the organism. The study suggests that (a) Hsp70 and anti-oxidant enzymes work together for cellular defense against xenobiotic hazard in D. melanogaster and (b) free radicals may modulate Hsp70 expression and apoptosis in the exposed organism. 相似文献