全文获取类型
收费全文 | 2810篇 |
免费 | 120篇 |
国内免费 | 1篇 |
专业分类
2931篇 |
出版年
2023年 | 30篇 |
2022年 | 51篇 |
2021年 | 72篇 |
2020年 | 52篇 |
2019年 | 53篇 |
2018年 | 91篇 |
2017年 | 64篇 |
2016年 | 112篇 |
2015年 | 122篇 |
2014年 | 134篇 |
2013年 | 217篇 |
2012年 | 240篇 |
2011年 | 209篇 |
2010年 | 136篇 |
2009年 | 127篇 |
2008年 | 137篇 |
2007年 | 133篇 |
2006年 | 111篇 |
2005年 | 86篇 |
2004年 | 75篇 |
2003年 | 74篇 |
2002年 | 43篇 |
2001年 | 48篇 |
2000年 | 35篇 |
1999年 | 27篇 |
1998年 | 17篇 |
1997年 | 16篇 |
1996年 | 18篇 |
1995年 | 13篇 |
1994年 | 9篇 |
1992年 | 25篇 |
1991年 | 19篇 |
1990年 | 22篇 |
1989年 | 17篇 |
1988年 | 24篇 |
1987年 | 18篇 |
1986年 | 22篇 |
1985年 | 23篇 |
1984年 | 19篇 |
1983年 | 24篇 |
1982年 | 12篇 |
1981年 | 13篇 |
1979年 | 18篇 |
1978年 | 9篇 |
1977年 | 12篇 |
1974年 | 12篇 |
1973年 | 7篇 |
1972年 | 18篇 |
1971年 | 12篇 |
1969年 | 10篇 |
排序方式: 共有2931条查询结果,搜索用时 15 毫秒
971.
Effect of Allium sativum on the immunity and survival of Labeo rohita infected with Aeromonas hydrophila 总被引:1,自引:0,他引:1
S. Sahu B. K. Das B. K. Mishra J. Pradhan N. Sarangi 《Zeitschrift fur angewandte Ichthyologie》2007,23(1):80-86
The aim of this study was to evaluate dietary dosages of garlic on the immune response and disease resistance against infections due to the opportunistic pathogen Aeromonas hydrophila in Labeo rohita fingerlings. Garlic, Allium sativum, was incorporated into the diets (0%, 0.1%, 0.5% and 1.0%) of rohu, L. rohita fingerlings (10 ± 2 g). Every 20 days, different biochemical (serum total protein, albumin, globulin, albumin : globulin ratio, blood glucose), haematological (WBC, RBC and haemoglobin content) and immunological (superoxide anion production, lysozyme activity and serum bactericidal activity) parameters were evaluated. Superoxide anion production, lysozyme, serum bactericidal, serum protein and albumin were enhanced in garlic treated groups compared with the control group. After 60 days, fish were challenged with A. hydrophila and mortality (%) was recorded up to day 10 post‐challenge. Survival decreased in control group (57%) up to day 10 after infection. However, this was increased in the garlic treatment group, i.e. 85% survivability in the 1 g garlic kg?1 (B group) and 5 g garlic kg?1 (C group), and 71% survivability in the 10 g garlic kg?1 (D group), respectively. These results indicate that Allium sativum stimulates the immunity and makes L. rohita more resistant to infection by A. hydrophila. 相似文献
972.
973.
The earlier works on the vibrational dynamics of polyglycine II (PG II) suffer from several infirmities, which not only suppress the dynamical nature of normal modes, but also lead to several incorrect assignments and interactive constants of the potential field. In this study, we have re-examined the phonon dispersion profiles of PG II using Higgs method for evaluation of phase-related normal modes and have attempted to remove the infirmities, as far as possible. The Wilson's GF matrix method combined with the Urey-Bradley force field has been used for normal mode analysis. This potential field leads to correct assignments of Raman, infrared and inelastic neutron scattering frequencies. Characteristic features of the dispersion curve (v versus delta/pi plot), such as repulsion and regions of high density-of-states have been interpreted. In addition, the heat capacity as a function of temperature has been obtained via density-of-states. It agrees well with the experimental data and is being reported for the first time. 相似文献
974.
Ria Biswas P.K. Dutta B. Achari Durba Bandyopadhyay Moumita Mishra K.C. Pramanik T.K. Chatterjee 《Phytomedicine》2007,14(7-8):534-537
The plant Pluchea indica is known for its anti-inflammatory, anti-ulcer, anti-pyretic, hypoglycemic, diuretic and anti-microbial activities besides many other pharmacological activities. We have isolated and purified seven compounds from the methanolic root extract of this plant by column chromatography. The compounds were identified by spectroscopic analyses. The anti-amoebic activities of the pure compound R/J/3 was investigated against the HM1 strain of Entamoeba histolytica. The compound, R/J/3 showed the most pronounced anti-proliferative activity at a dose of 50 microg/ml. It also showed a marked activity on cell lysis of trophozoites, 4h after administration. The cell lytic activity was compared with metronidazole (5 microg/ml) as positive control. 相似文献
975.
Tiwari AK Mishra AK Bajpai A Mishra P Singh S Sinha D Singh VK 《Bioorganic & medicinal chemistry letters》2007,17(10):2749-2755
Two different benzimidazole analogues act as multimodal agent, first one as novel non-peptidic CCK-B receptor antagonist and similarly as potent anti-fungal agent, designated as [Bz-Im]. These compounds were synthesized and characterized by spectroscopic techniques such as FT-IR, NMR, EI-MS and also evaluated for specific radiopharmaceuticals. Preliminary radiolabeling results with (99m)Tc and biological evaluation studies showed promising results for further evaluation in vivo. The efficiency of labeling was more than 97% and complex was stable for about 12h at 30 degrees C in the presence of serum. Both ligands showed binding to most of the organs, known to express CCK receptors in biodistribution studies. Cholecystokinin (CCK(1) andCCK(2)) receptor binding affinities of these analogues are, IC(50), 0.942+/-0.107 for compound C and 0.665+/-0.211 for compound D in rat pancreatic acini. The anti-fungal activity has shown inhibitory activity against Aspergillus flavus and Aspergillus niger. These studies have provided a new template for further development of non-peptidic ligands for diagnostic and therapeutic purposes of diseases related with CCK receptors as well as anti-microbes. 相似文献
976.
Sodhi M Mukesh M Prakash B Mishra BP Sobti RC Singh KP Singh S Ahlawat SP 《Biochemical genetics》2007,45(1-2):145-153
The MspI allelic variation in intron III of the bovine growth hormone (bGH) gene was explored using PCR-RFLP in 750 animals
belonging to 17 well-recognized breeds of Indian zebu cattle (Bos indicus) reared in different geographic locations of the
country. Restriction digestion analysis of a 329-bp PCR fragment of the bGH intron III region with MspI restriction enzyme
revealed two alleles (MspI− and MspI+) and two genotypes (−/− and +/−) across the 17 cattle breeds studied. The allelic frequency
varied from 0.67 to 0.94 for MspI (−) and from 0.06 to 0.33 for MspI (+) across the 17 breeds, with a combined average frequency
of 0.87 and 0.13, respectively. No animal with +/+ genotype was detected across the samples analyzed. The chi-square test
showed that the difference in MspI allelic frequency was not significant (p > 0.05), regardless of the geographic origin,
coat color, or utility of the cattle breed. The high MspI (−) allele frequencies obtained for Indian zebu cattle in this study
are in sharp contrast to those reported for taurine breeds from northern Europe, Mediterranean countries, and America. Findings
of this study further substantiate the hypothesis that the MspI (−) allele has an Indian origin. 相似文献
977.
978.
Ruchika Dadhich Abhishek Singh Anjana P. Menon Manjari Mishra Shobhna Kapoor 《生物化学与生物物理学报:生物膜》2019,1861(6):1213-1227
Lipid structure critically dictates the molecular interactions of drugs with membranes influencing passive diffusion, drug partitioning and accumulation, thereby underpinning a lipid-composition specific interplay. Spurring selective passive drug diffusion and uptake through membranes is an obvious solution to combat growing antibiotic resistance with minimized toxicities. However, the spectrum of complex mycobacterial lipids and lack thereof of suitable membrane platforms limits the understanding of mechanisms underlying drug-membrane interactions in tuberculosis. Herein, we developed membrane scaffolds specific to mycobacterial outer membrane and demonstrate them as improvised research platforms for investigating anti-tubercular drug interactions. Combined spectroscopy and microscopy results reveal an enhanced partitioning of model drug Rifabutin in trehalose dimycolate-containing mycobacterial membrane systems. These effects are apportioned to specific changes in membrane structure, order and fluidity leading to enhanced drug interaction. These findings on the membrane biophysical consequences of drug interactions will offer valuable insights for guiding the design of more effective antibiotic drugs coupled with tuned toxicity profiles. 相似文献
979.
Rajan K. Pandey Rupal Ojha Nina Chatterjee Nitesh Upadhyay Amit Mishra Vijay K. Prajapati 《Journal of cellular physiology》2019,234(6):8717-8726
Human T-lymphotropic virus (HTLV), the first human retrovirus has been discovered which is known to cause the age-old assassinating disease HTLV-1 associated myelopathy. Cancer caused by this virus is adult T cell leukemia/lymphoma which targets 10–20 million throughout the world. The effect of this virus extends to the fact that it causes chronic disease to the spinal cord resulting in loss of sensation and further causes blood cancer. So, to overcome the complications, we designed a subunit vaccine by the assimilation of B-cell, cytotoxic T-lymphocyte , and helper T-lymphocyte epitopes. The epitopes were joined together along with adjuvant and linkers and a vaccine was fabricated which was further subjected to 3D modeling. The physiochemical properties, allergenicity, and antigenicity were evaluated. Molecular docking and dynamics were performed with the obtained 3D model against toll like receptor (TLR-3) immune receptor. Lastly, in silico cloning was performed to ensure the expression of the designed vaccine in pET28a(+) expression vector. The future prospects of the study entailed the in vitro and in vivo experimental analysis for evaluating the immune response of the designed vaccine construct. 相似文献
980.
In Anabaena sp. PCC 7120, iron is an essential trace element and its availability determines proper functioning of several kinds of metabolisms. Iron deficiency leads to several unavoidable consequences including membrane damage. In the present study, we dealt with the impact of iron deficiency on NtcA (global nitrogen regulator)‐dependent regulation of two important processes, i.e. fatty acid desaturation and heterocyte envelop formation in cyanobacterium Anabaena sp. PCC 7120. In Anabaena sp. PCC 7120, NtcA regulates fatty acid desaturation by regulating enzyme fatty acid desaturases. The NtcA‐based regulation of fatty acid desaturation may be direct or indirect. Furthermore, the expression of genes involved in the heterocyte envelope polysaccharide (HEP) layer formation (hepABCK) and heterocyte‐specific glycolipids (HGLs) synthesis (devH, hglEA, prpJ and devB) were also under the control of NtcA and reduced under iron deficiency background. The enhanced expression of furA and early downregulation of ntcA under iron deficiency is responsible for reduction in fatty acid desaturation as well as decrease in the expression of genes involved in HEP layer formation and HGL synthesis. Overall results confirmed that iron deficiency influences the NtcA‐based regulation of fatty acid desaturation and heterocyte envelop formation in Anabaena sp. PCC 7120. 相似文献