全文获取类型
收费全文 | 1698篇 |
免费 | 67篇 |
国内免费 | 3篇 |
出版年
2023年 | 21篇 |
2022年 | 46篇 |
2021年 | 77篇 |
2020年 | 56篇 |
2019年 | 50篇 |
2018年 | 73篇 |
2017年 | 58篇 |
2016年 | 92篇 |
2015年 | 89篇 |
2014年 | 108篇 |
2013年 | 133篇 |
2012年 | 165篇 |
2011年 | 143篇 |
2010年 | 89篇 |
2009年 | 69篇 |
2008年 | 65篇 |
2007年 | 49篇 |
2006年 | 40篇 |
2005年 | 47篇 |
2004年 | 34篇 |
2003年 | 37篇 |
2002年 | 26篇 |
2001年 | 24篇 |
2000年 | 21篇 |
1999年 | 13篇 |
1998年 | 7篇 |
1997年 | 6篇 |
1996年 | 5篇 |
1995年 | 4篇 |
1994年 | 10篇 |
1993年 | 7篇 |
1992年 | 14篇 |
1991年 | 11篇 |
1990年 | 8篇 |
1989年 | 5篇 |
1988年 | 4篇 |
1986年 | 6篇 |
1985年 | 6篇 |
1984年 | 3篇 |
1983年 | 3篇 |
1982年 | 5篇 |
1981年 | 3篇 |
1980年 | 4篇 |
1978年 | 5篇 |
1977年 | 3篇 |
1976年 | 4篇 |
1975年 | 4篇 |
1973年 | 2篇 |
1972年 | 6篇 |
1971年 | 2篇 |
排序方式: 共有1768条查询结果,搜索用时 31 毫秒
991.
Chemical screening of some profusely growing wild leguminous seeds of Acacia, Albizzia and Leucaena species, for their nutritional constituents suggested the possibility of their inclusion in animal nutrition. However, since the whole seeds proved to be unpalatable as well as toxic in some cases, it was thought of utility to employ their isolated proteins instead. Accordingly, with a view to explore newer and effective sources of dietary proteins, simple and effective solubility method was employed for their extraction, precipitation, fractionation and isolation from the undesirable wild seed constituents to obtain the protein fractions in the pure form which could be incorporated in animal nutrition. Distribution of total nitrogen and dispersion of nitrogenous constituents in the seeds have also been studied. Extraction of proteins of considerable purity is best effected with sodium chloride solution (5%, w/v) and subsequent dialysis of the extract. Proteins were isolated from seven varieties of leguminous seeds by acid-alkali extraction method and their protein efficiency ratio and the biological value have been evaluated by animal experiments with and without supplementing the isolated protein diets with the missing essential amino acids. 相似文献
992.
993.
P. Gopinath R.K. Yadav P.K. Shukla K. Srivastava S.K. Puri K.M. Muraleedharan 《Bioorganic & medicinal chemistry letters》2017,27(5):1291-1295
Various mono- and bis-benzisothiazolone derivatives were synthesized and screened against different strains of bacteria and fungi in order to understand the effect of multiple electrophilic sulfur atoms and substitution pattern in the immediate vicinity of reactive sulfur. Staphyllococcus aureus-ATCC 7000699, MRSA and S. aureus-ATCC 29213 (Quality Control strain) were more susceptible to this class of compounds, and the most potent derivative 1.15 had MIC50 of 0.4 μg/mL (cf. Gentamicin = 0.78 μg/mL). CLogP value, optimally in the range of 2.5–3.5, appeared to contribute more to the activity than the steric and electronic effects of groups attached at nitrogen. By and large, their anti-fungal activities also followed a similar trend with respect to the structure and CLogP values. The best potency of IC50 = 0.1 μg/mL was shown by N-benzyl derivative (1.7) against Aspergillus fumigatus; it was also potent against Candida albicans, Cryptococcus neoformans, Sporothrix schenckii, and Candida parapsilosis with IC50 values ranging from 0.4 to 1.3 μg/mL. Preliminary studies also showed that this class of compounds have the ability to target malaria parasite with IC50 values in low micromolar range, and improvement of selectivity is possible through structure optimization. 相似文献
994.
995.
Yadav Birendra Singh Singh Swati Srivastava Sameer Singh Nand Kumar Mani Ashutosh 《Journal of plant biochemistry and biotechnology.》2019,28(3):345-352
Journal of Plant Biochemistry and Biotechnology - Heavy metal stress is a major environmental factor responsible for limiting the production of crops. Whole genome wide expression and functional... 相似文献
996.
John P. Voris Leonid A. Sitailo Heidi R. Rahn Ann Defnet Aaron T. Gerds Robert Sprague Vipin Yadav I. Caroline Le Poole Mitchell F. Denning 《Pigment cell & melanoma research》2010,23(2):216-224
Protein kinase C (PKC) is a heterogeneous family of serine/threonine protein kinases that have different biological effects in normal and neoplastic melanocytes (MCs). To explore the mechanism behind their differential response to PKC activation, we analyzed the expression profile of all nine PKC isoforms in normal human MCs, HPV16 E6/E7 immortalized MCs, and a panel of melanoma cell lines. We found reduced PKCβ and increased PKCζ and PKCι expression at both the protein and mRNA levels in immortalized MCs and melanoma lines. We focused on PKCβ as it has been functionally linked to melanin production and oxidative stress response. Re-expression of PKCβ in melanoma cells inhibited colony formation in soft agar, indicating that PKCβ loss in melanoma is important for melanoma growth. PKCβII, but not PKCβI, was localized to the mitochondria, and inhibition of PKCβ significantly reduced UV-induced reactive oxygen species (ROS) in MCs with high PKCβ expression. Thus alterations in PKCβ expression in melanoma contribute to their neoplastic phenotype, possibly by reducing oxidative stress, and may constitute a selective therapeutic target. 相似文献
997.
P. Anuradha Reddy A. Kumaraguru P. Raghuveer Yadav A. Ramyashree Jyotsna Bhagavatula Sisinthy Shivaji 《European Journal of Wildlife Research》2011,57(3):517-522
A decade back, almost 300,000 km2 of forests in India were estimated to be potential tiger habitat. But consistent degradation and unsustainable anthropogenic
pressures have adversely affected tiger presence in most of the forests outside the better protected tiger reserves. Here
we use Geographic Information System data to analyze the degree of vegetation loss and landscape changes over the last decade
(1998–2006), and ascertain the presence of tigers in a degraded forest like the Kawal Wildlife Sanctuary, Andhra Pradesh,
India, by non-invasive fecal DNA analysis. Vegetation cover maps show a clear degradation of the sanctuary within a decade.
DNA analysis of scat samples reveals tiger presence in areas where closed dense forest canopy has persisted with minimal human
disturbance during the last decade. 相似文献
998.
999.
1000.
Metallic nanoparticles are widely used in cosmetics, food products and textile industry. These particles are known to cause respiratory toxicity and epithelial inflammation. They are eventually released to aquatic environment necessitating toxicity studies in cells from respiratory organs of aquatic organisms. Hence, we have developed and characterized a new cell line, WAG, from gill tissue of Wallago attu for toxicity assessment of TiO2 and ZnO nanoparticles. The efficacy of the cell line as an in vitro system for nanoparticles toxicity studies was established using electron microscopy, cytotoxicity assays, genotoxicity assays and oxidative stress biomarkers. Results obtained with MTT assay, neutral red uptake assay and lactate dehydrogenase assay showed acute toxicity to WAG cells with IC50 values of 25.29±0.12, 34.99±0.09 and 35.06±0.09 mg/l for TiO2 and 5.716±0.1, 3.160±0.1 and 5.57±0.12 mg/l for ZnO treatment respectively. The physicochemical properties and size distribution of nanoparticles were characterized using electron microscopy with integrated energy dispersive X-ray spectroscopy and Zetasizer. Dose dependent increase in DNA damage, lipid peroxidation and protein carbonylation along with a significant decrease in activity of Superoxide Dismutase, Catalase, total Glutathione levels and total antioxidant capacity with increasing concentration of exposed nanoparticles indicated that the cells were under oxidative stress. The study established WAG cell line as an in vitro system to study toxicity mechanisms of nanoparticles on aquatic organisms. 相似文献