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排序方式: 共有183条查询结果,搜索用时 15 毫秒
1.
Lalita K. Shekhawat 《Preparative biochemistry & biotechnology》2013,43(6):623-638
AbstractLiquid chromatography is considered to be the bottleneck for purification of therapeutic proteins. Development and optimization of chromatography process is a cumbersome activity due to the increasing complexities in the types and content of impurities present in the high product titer cell culture harvest obtained from the upstream processing. Further, regulatory expectations are continuously rising with the recent initiatives of quality by design and process analytical technology expecting the manufacturer to have a deeper understanding of the process and the product. Mechanistic modeling is one approach to gain this deeper understanding of a process step. It involves modeling of the underlying physicochemical processes. A well calibrated model with acceptable predictability can be very effective in both process optimization and process characterization activities. In this paper we provide an overview of mechanistic modeling of liquid chromatography. We discuss the various components that such a model entails and also presents the status quo of this area. 相似文献
2.
Keith W.T.Goulding 《中国科学:生命科学英文版》2005,48(Z2)
The nitrogen (N) cycle is essentially 'leaky'. The losses of small amounts of nitrate to waters and of ammonia and nitrous oxide to the atmosphere are a part of the global biogeo-chemical N cycle. However, intensive agricultural production, industry and vehicle use have more than doubled the amount of 'reactive' N in the environment, resulting in eutrophication, ecosystem change and health concerns. Research has identified agricultural practices that cause large losses of N and, in some cases, developed solutions. This paper discusses the problems of maintaining productivity while reducing N losses, compares conventional with low input (integrated) and organic farming systems, and discusses wider options. It also looks at the need to integrate studies on N with other environmental impacts, set in the context of the whole farm system, to provide truly sustainable agricultural systems. 相似文献
3.
Differential survival and reproduction in colour forms of Philaenus spumarius give new insights to the study of its balanced polymorphism 总被引:1,自引:0,他引:1 下载免费PDF全文
EDUARDO MARABUTO SELÇUK YURTSEVER PAULO A. V. BORGES JOSÉ A. QUARTAU OCTÁVIO S. PAULO SOFIA G. SEABRA 《Ecological Entomology》2015,40(6):759-766
1. Colour polymorphisms are common across animals and are often the result of complex selection regimes. Philaenus spumarius (Linnaeus) (Hemiptera, Aphrophoridae) shows a widely studied dorsal colour polymorphism with several described phenotypes whose variation in their occurrence and frequency, as well as their maintenance across time, have been reported. Several selective influences have been suggested to play a role, but the mechanisms underlying the maintenance of this polymorphism are still poorly understood. 2. To explore the adaptive significance of the colour polymorphism of P. spumarius, an experiment was conducted in captivity under semi‐natural conditions to measure survival, reproductive success, and duration of egg maturation. 3. It was found that there was higher longevity, a higher number of oviposition events, and a higher number of eggs laid by trilineatus phenotype females than by typicus and marginellus, supporting previous reports of an increase in trilineatus frequency during the season. The duration of egg maturation did not differ among phenotypes. 4. The higher longevity and fertility of the trilineatus phenotype may compensate, for example, the higher rate of attack by parasitoids and/or higher solar radiation reflectance in this phenotype, which have already been reported in previous studies, constituting a possible mechanism for the maintenance of this polymorphism. 相似文献
4.
There are major concerns over both the security of energy supplies (declining supplies and political control) and the environmental costs associated with energy generation and use.The global consumption of carbon-containing fossil fuels for 相似文献
5.
Angela Karp Steve J.Hanley Sviatlana O.Trybush William Macalpine Ian Shield 《Acta Botanica Sinica》2011,(2)
Willows (Salix spp.) are a very diverse group of catkin-bearing trees and shrubs that are widely distributed across temperate regions of the globe.Some species respond well to being grown in short rotation coppice (SRC) cycles,which are much shorter than conventional forestry.Coppicing reinvigorates growth and the biomass rapidly accumulated can be used as a source of renewable carbon for bioenergy and biofuels.As SRC willows re-distribute nutrients during the perennial cycle they require only minimal nitro... 相似文献
6.
Kannan N. Manokari M. Shekhawat Mahipal S. 《Plant Cell, Tissue and Organ Culture》2021,145(2):457-460
Plant Cell, Tissue and Organ Culture (PCTOC) - The present communication reports, induction of adventitious roots (AR) from the in vitro raised leaves of Morinda coreia as affected by auxins and... 相似文献
7.
P Sharma SK Tuteja V Bhalla G Shekhawat VP Dravid CR Suri 《Biosensors & bioelectronics》2013,39(1):99-105
We report a novel in-situ electrochemical synthesis approach for the formation of functionalized graphene-graphene oxide (fG-GO) nanocomposite on screen-printed electrodes (SPE). Electrochemically controlled nanocomposite film formation was studied by transmission electron microscopy (TEM) and Raman spectroscopy. Further insight into the nanocomposite has been accomplished by the Fourier transformed infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA) and X-ray diffraction (XRD) spectroscopy. Configured as a highly responsive screen-printed immunosensor, the fG-GO nanocomposite on SPE exhibits electrical and chemical synergies of the nano-hybrid functional construct by combining good electronic properties of functionalized graphene (fG) and the facile chemical functionality of graphene oxide (GO) for compatible bio-interface development using specific anti-diuron antibody. The enhanced electrical properties of nanocomposite biofilm demonstrated a significant increase in electrochemical signal response in a competitive inhibition immunoassay format for diuron detection, promising its potential applicability for ultra-sensitive detection of range of target analytes. 相似文献
8.
Nitika Singh Rathore Nisha Rathore N. S. Shekhawat 《Acta Physiologiae Plantarum》2013,35(9):2691-2698
We developed a micropropagation protocol for Cleome gynandra, a C4 model plant with medicinal importance. Surface-sterilized nodal segments obtained from 1 to 2-month-old field grown plant were used as explants for culture establishment and plant regeneration. Multiple shoots differentiated through bud breaking on Murashige and Skoog (MS) medium with different concentrations of benzyladenine (BA) and kinetin (Kin). The optimum shoot differentiation occurred on medium with 1.5 mg l?1 BA. Out of various concentrations and combinations of cytokinins and auxins, MS medium containing 0.5 mg l?1 BA and 0.1 mg l?1 IAA (indole-3-acetic acid) was found best for shoot multiplication. However, the differentiated shoots exhibited hyperhydration, leaf curling and early leaf fall during subculturing. To overcome these problems, regenerated shoots were transferred to the modified MS medium with reduced nitrates (825 mg l?1 NH4NO3 and 950 mg l?1 KNO3) and 100 mg l?1 (NH4)2SO4. The micropropagated shoots were rooted (i) in vitro on one-fourth strength of MS salts with 0.25 mg l?1 each of IBA (indole-3 butyric acid) and NOA (2-naphthoxyacetic acid) + 100 mg l?1 activated charcoal, and (ii) ex vitro, by treating the shoot base(s) with 200 mg l?1 of IBA for 3 min and transferred to soilrite moistened with one-fourth strength of MS macro salts in culture bottles. The plants were hardened in the greenhouse with 85 % survival rate. Micromorphological studies of the plants were conducted during hardening with reference to development and changes in vein spacing, glandular trichome and stomata. In comparison to leaves under in vitro condition, higher density of veins and glandular trichomes was observed in the leaves of hardened plants. In addition, stomata became functional during hardening which were non-functional under in vitro condition. 相似文献
9.
Sucrose-inducible expression of hepatitis B surface antigen using potato granule-bound starch synthase promoter 总被引:2,自引:0,他引:2
U. K. S. Shekhawat T. R. Ganapathi G. B. Sunil Kumar L. Srinivas 《Plant biotechnology reports》2007,1(4):199-206
NT-1 cells of tobacco (Nicotiana tabacum L.) were transformed with pGBSSHBS and pGBSSHER expression cassettes wherein expression of hepatitis B surface antigen (HBsAg)
was driven by potato granule-bound starch synthase (GBSS) promoter. The transformed nature of the cells was confirmed by PCR
analysis. Expression of HBsAg was confirmed by RT-PCR and Western blotting and levels of expression were assayed by ELISA.
Transformed cell lines exhibited a sucrose-inducible pattern of HBsAg expression. NT-1 medium supplemented with 175 mmol L−1 sucrose gave the highest HBsAg expression of 198 ng g−1 FW after 8 days of induction. Different sugars, for example glucose, fructose, and palatinose, were also tested to study
the inducible nature of GBSS promoter. The results demonstrate that potato GBSS promoter can be used in heterologous host
systems like tobacco NT-1 cell suspension cultures for sucrose-inducible expression of recombinant proteins. 相似文献