全文获取类型
收费全文 | 685篇 |
免费 | 30篇 |
专业分类
715篇 |
出版年
2023年 | 2篇 |
2022年 | 13篇 |
2021年 | 19篇 |
2020年 | 14篇 |
2019年 | 12篇 |
2018年 | 12篇 |
2017年 | 8篇 |
2016年 | 18篇 |
2015年 | 30篇 |
2014年 | 32篇 |
2013年 | 49篇 |
2012年 | 40篇 |
2011年 | 47篇 |
2010年 | 44篇 |
2009年 | 33篇 |
2008年 | 36篇 |
2007年 | 29篇 |
2006年 | 29篇 |
2005年 | 42篇 |
2004年 | 37篇 |
2003年 | 34篇 |
2002年 | 35篇 |
2001年 | 4篇 |
2000年 | 3篇 |
1999年 | 10篇 |
1998年 | 6篇 |
1996年 | 5篇 |
1995年 | 3篇 |
1994年 | 4篇 |
1993年 | 3篇 |
1990年 | 2篇 |
1989年 | 4篇 |
1987年 | 4篇 |
1986年 | 3篇 |
1985年 | 3篇 |
1984年 | 4篇 |
1983年 | 4篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1980年 | 13篇 |
1979年 | 2篇 |
1976年 | 2篇 |
1975年 | 3篇 |
1971年 | 1篇 |
1970年 | 1篇 |
1966年 | 2篇 |
1965年 | 1篇 |
1964年 | 1篇 |
1963年 | 1篇 |
1962年 | 3篇 |
排序方式: 共有715条查询结果,搜索用时 0 毫秒
1.
2.
3.
Hypocotyl segments, 5 to 8 mm length from 4 to 7 day old seedlings, callused on B5 medium supplemented with Kn (0.5 ppm) and NAA (0.1 ppm). Even without transfer, shoots were formed in such cultures. About 20% of the cultures produced multiple shoots. In medium with 1 ppm each of Kn and NAA direct shoots were formed at one end of the hypocotyl segment and callusing was initiated at the other end. The plants obtained in either medium formed roots and could be transferred to soil for further growth.Abbreviations BA
benzyladenine
- 2,4-D
2,4-dichlorophenoxy acetic acid
- GA3
gibberellic acid
- Kn
Kinetin
- NAA
naphthalene acetic acid 相似文献
4.
Poonam Kakkar Sudhir Mehrotra P. N. Viswanathan 《Molecular and cellular biochemistry》1992,111(1-2):11-15
Incubation of freshly isolated rat liver mitochondria in the presence of oxygen free radical generating hypoxanthine —xanthine oxidase system led to swelling of mitochondria as measured by the change in optical density, which was reversed by the addition of superoxide dismutase. O2
– in the presence of CaCl2 enhanced the peroxidative decomposition of mitochondrial membrane lipids along with swelling of the organelle. Free radical generation led to enhancement of monoamine oxidase activity while glutathione peroxidase and cytochrome c oxidase were inhibited. Tertbutyl hydroperoxide (t-BHP) caused mitochondrial swelling through oxidative stress. Incorporation of ruthenium red, which is a Ca2+ transport blocker, during assay abolished peroxidative membrane damage and swelling. Dithiothreitol (DTT) accorded protection against t-BHP induced mitochondrial swelling. The above in vitro data suggest a possible interrelationship of active oxygen species, membrane damage and calcium dynamics. 相似文献
5.
Sunil Palchaudhuri Ranajit Kumar Dipak Sen Ruma Pal Sajal Ghosh Banwarilal Sarkar Sujit K. Bhattacharya Sudhir C. Pal 《FEMS microbiology letters》1985,30(1-2):187-191
Abstract Multiple antibiotic-resistant Shigella dysenteriae type 1 isolates from a recent epidemic in West Bengal (India) showed identical plasmid patterns. All isolates were resistant to ampicillin (Am), chloramphenicol (Cm), tetracycline (Tc), streptomycin (Sm) and trimethoprim (Tp) and contained 6 plasmids, ranging from 2.5–120 kb. The Am resistance determinant was located on the 120 kb plasmid. This plasmid was unstable when the S. dysenteriae strains were grown above 37°C. The Bangladesh strains of S. dysenteriae type 1 showed identical plasmid patterns, except that many isolates were Am-sensitive and lacked the 120 kb plasmid. In strains from both Bangladesh and West Bengal, predominantly group-B plasmids conferred resistance to Cm and Tc. Comparisons of Eco R1 fragments generated from the total plasmid DNA content of each strain support the view that the plasmids present in the S. dysenteriae type 1 strains isolated from all recent epidemics in India and Bangladesh were identical. 相似文献
6.
Site-related differences in the localization of the monoclonal antibody OX7 in SL2 and SL1 lymphomas
Howard Sands Peter L. Jones William P. Neacy Sudhir A. Shah Brian M. Gallagher 《Cancer immunology, immunotherapy : CII》1986,22(3):169-175
Summary The uptake of a monoclonal antibody (OX7) by murine lymphomas (SL1, SL2) growing in two sites in the mouse were compared. SL2 tumors grown in the subrenal site showed greater specific antibody uptake than did the same tumor grown in the subcutaneous site. Major differences in membrane bound antibody, in vitro antibody binding patterns, and gamma scintillation camera imaging were also observed between the two sites. These differences may be due to the greater blood flow measured in tumors growing in the subrenal capsule than those growing at the subcutaneous site. The differences observed in antibody uptake of the same tumor growing in two different sites raises questions concerning the choice of animal model systems that can be used to predict clinical utility. 相似文献
7.
Evolutionary relationships of eukaryotic kingdoms 总被引:5,自引:0,他引:5
The evolutionary relationships of four eukaryotic kingdoms—Animalia, Plantae, Fungi, and Protista—remain unclear. In particular, statistical support for the closeness of animals to fungi rather than to plants is lacking, and a preferred branching order of these and other eukaryotic lineages is still controversial even though molecular sequences from diverse eukaryotic taxa have been analyzed. We report a statistical analysis of 214 sequences of nuclear small-subunit ribosomal RNA (srRNA) gene undertaken to clarify these evolutionary relationships. We have considered the variability of substitution rates and the nonindependence of nucleotide substitution across sites in the srRNA gene in testing alternative hypotheses regarding the branching patterns of eukaryote phylogeny. We find that the rates of evolution among sites in the srRNA sequences vary substantially and are approximately gamma distributed with size and shape parameter equal to 0.76. Our results suggest that (1) the animals and true fungi are indeed closer to each other than to any other crown group in the eukaryote tree, (2) red algae are the closest relatives of animals, true fungi, and green plants, and (3) the heterokonts and alveolates probably evolved prior to the divergence of red algae and animal-fungus-green-plant lineages. Furthermore, our analyses indicate that the branching order of the eukaryotic lineages that diverged prior to the evolution of alveolates may be generally difficult to resolve with the srRNA sequence data. 相似文献
8.
Enzymatic labeling of nucleic acids is a fundamental tool in molecular biology with virtually every aspect of nucleic acid
hybridization technique involving the use of labeled probes. Different methods for enzymatic labeling of DNA, RNA and oligonucleotide
probes are available today. In this review, we will describe both radioactive and nonradioactive labeling methods, yet the
choice of system for labeling the probe depends on the application under study. 相似文献
9.
Summary Optimisation of reaction conditions for the esterification of geraniol of palmarosa oil with n-butyric acid using immobilized lipase from Mucor miehei in non-aqueous system was carried out. Palmarosa oil could be easily esterified upto 95% w/w at 40°C in 24 h. Effect of moisture content was studied using Na2SO4 and recycling of the immobilized enzyme. 相似文献
10.
A suspension ofPlasmodium berghei obtained by lysis with saponin of red blood cells from an infected rat showed high hemolytic activity, when incubatedin vitro with normal rat red blood cells. The hemolysis was a temperature-dependent process and was dependent on the concentration
of the parasite. Plasma ofPlasmodium berghei infected albino rats also possessed lytic activity. 相似文献