全文获取类型
收费全文 | 1901篇 |
免费 | 128篇 |
出版年
2023年 | 14篇 |
2022年 | 20篇 |
2021年 | 52篇 |
2020年 | 22篇 |
2019年 | 34篇 |
2018年 | 48篇 |
2017年 | 28篇 |
2016年 | 52篇 |
2015年 | 99篇 |
2014年 | 102篇 |
2013年 | 144篇 |
2012年 | 162篇 |
2011年 | 135篇 |
2010年 | 78篇 |
2009年 | 61篇 |
2008年 | 75篇 |
2007年 | 88篇 |
2006年 | 81篇 |
2005年 | 77篇 |
2004年 | 74篇 |
2003年 | 75篇 |
2002年 | 59篇 |
2001年 | 33篇 |
2000年 | 27篇 |
1999年 | 22篇 |
1998年 | 12篇 |
1996年 | 11篇 |
1995年 | 14篇 |
1994年 | 12篇 |
1993年 | 15篇 |
1992年 | 12篇 |
1991年 | 19篇 |
1990年 | 14篇 |
1989年 | 15篇 |
1988年 | 22篇 |
1987年 | 26篇 |
1986年 | 17篇 |
1985年 | 18篇 |
1984年 | 15篇 |
1982年 | 10篇 |
1981年 | 9篇 |
1980年 | 8篇 |
1979年 | 12篇 |
1978年 | 14篇 |
1977年 | 7篇 |
1976年 | 10篇 |
1975年 | 13篇 |
1973年 | 6篇 |
1972年 | 6篇 |
1971年 | 6篇 |
排序方式: 共有2029条查询结果,搜索用时 46 毫秒
121.
122.
123.
Jadhao SJ Kataria JM Deepak JN Verma KC Kataria RS Tiwari AK 《Indian journal of experimental biology》2000,38(2):186-188
A rapid method of ultracentrifugation pelleting of avian adenovirus (AAV) from small volume of chloroform treated infected cell culture fluid or allantoic fluid was adapted for isolation of adenoviral DNA. The viral DNA extracted from semipurified viruses was found to be intact on agarose gel and pure enough (A260/280 = 1.85-1.92) for restriction enzyme analysis. Restriction endonuclease analysis of Indian strain of AAV serotype 1, AAV serotype 4 (group I AAVs) and egg drop syndrome-76 (EDS-76) virus genomes (group III AAV) with Hind III enzyme differentiated these viruses. The AAV serotype 1 and serotype 4 strain exhibited identical Hind III profile to European viral strains belonging to same serotypes however, the EDS-76 virus gave similar but not identical profile. The calculated genomic lengths for AAV serotype 1 and EDS-76 virus were approximately found to be 33.9 and 44.4 Kb, respectively. 相似文献
124.
Transformation of Nicotiana tabacum with a native cry1Ia5 gene confers complete protection against Heliothis armigera 总被引:2,自引:0,他引:2
Selvapandiyan Angamuthu Reddy Vanga S. Kumar P. Anand Tewari Krishna K. Bhatnagar Raj K. 《Molecular breeding : new strategies in plant improvement》1998,4(6):473-478
A cry1Ia5 insecticidal toxin coding gene has been cloned from an Indian isolate of Bacillus thuringiensis. Sequence analyses of the cry1Ia5 gene revealed the absence of potential polyadenylation signal sequences thus making it a suitable candidate for expression in plants without extensive modification. This possibility was examined by subcloning the cry1Ia5 gene into a plant expression vector and then transferring it to Nicotiana tabacum through Agrobacterium-mediated transformation. Our results demonstrate that N. tabacum with a stably integrated native cry1Ia5 gene afforded complete protection against predation by Heliothis armigera. Forty three percent of the transgenic plants displayed a high level of protection against insect predation. The protection obtained in transgenic plants with the cry1Ia5 gene was comparable to that obtained with the synthetically modified cry1A(b) or cry1A(c) genes. The results demonstrate that novel insecticidal genes already exist in nature that do not require extensive modifications for efficient expression in plants. 相似文献
125.
The biodegradation and toxicity of tetrachloroethylene (C2Cl4) and trichloroethylene (C2HCl3) were studied with different anaerobic enrichment cultures using the following electron donors: acetate, propionate, butyrate,
methanol, formate and hydrogen. All of them sustained dechlorination except propionate, for which C2Cl4 biodegradation rates were not significant. The best results were obtained with butyrate. Hydrogen appeared to be a relevant
electron donor for dechlorination with the present cultures. In the presence of specific inhibitors such as bromoethanesulphonate
or molybdate, a slight inhibition of dechlorination was observed. According to dechlorination kinetics, Monod-type behaviour
was observed up to 120 μM C2Cl4 or 200 μM C2HCl3 with K
s values around 7 μM for both compounds. Dechlorination was partially inhibited at higher concentrations. In contrast, methanogens,
or at least methane production, were more sensitive to the presence of chlorinated ethylenes and inhibition of methanogenesis
was observed to different extents over all the C2Cl4/C2HCl3 concentration range tested, even at the lowest concentrations.
Received: 17 April 1998 / Received revision: 18 June 1998 / Accepted: 19 June 1998 相似文献
126.
CGS 16949A is a potent inhibitor of aromatase in vitro with an IC50 of 0.03 microM for the inhibition of LH-stimulated estrogen biosynthesis in hamster ovaries. In vivo, CGS 16949A leads to sequelae of estrogen deprivation (e.g. regression of DMBA-induced mammary tumors) without causing adrenal hypertrophy in adult rats. To complement these in vitro and in vivo findings, the effect of CGS 16949A on adrenal steroid biosynthesis in rats was investigated in vitro and in vivo. The surprising finding in vitro was that CGS 16949A inhibited aldosterone biosynthesis (IC50 = 1 microM) at concentrations 100 times lower than those for inhibition of corticosterone biosynthesis (IC50 = 100 microM). Moreover, deoxycorticosterone (DOC) concentrations were elevated at all concentrations of CGS 16949A which inhibited aldosterone synthesis. The classical biosynthetic pathway for aldosterone is DOC----corticosterone----18-OH-corticosterone----aldosterone. Thus inhibition of aldosterone biosynthesis, reflected in DOC accumulation, without affecting corticosterone concentrations, indicates that corticosterone is not an obligatory intermediate in the conversion of DOC to aldosterone in the rat. In vivo, CGS 16949A showed a suppression of plasma aldosterone in ACTH-stimulated male rats at doses which did not significantly affect plasma corticosterone. In conclusion, aldosterone measured both in vitro and in vivo must be derived primarily from a biosynthetic pathway in which corticosterone is not obligatory intermediate. 相似文献
127.
Kumaravel Ilangovan Sharath Burugina Nagaraja Ramya Ananthakrishnan Anil G. Jacob Jaya Prasad Tripathy Deepak Tamang 《PloS one》2015,10(4)
Background
In India, the Revised National TB Control Programme (RNTCP) envisages initiation of TB treatment within seven days of diagnosis among smear-positive patients. After nearly two decades of RNTCP implementation, treatment delays are usually not expected.Objectives
To determine the proportion of sputum smear-positive TB patients who were initiated on treatment after seven days and their associated risk factors.Methods
The study was conducted in Cuttack and Rayagada districts of Odisha. It was a retrospective cohort study that involves review of TB treatment registers and laboratory registers for 2013.Results
Among 1,800 pulmonary TB (PTB) patients, 1,074 (60%) had been initiated on treatment within seven days of diagnosis, 721 (40%) had been initiated on treatment more than seven days, and 354 (20%) had delays of more than 15 days. The mean duration between TB diagnosis and treatment initiation was 21 days with a range of 8–207 days (median = 14 days). Odds of treatment delay of more than seven days were 4.9 times (95% confidence interval [CI] 3.3-6.6) among those who had been previously treated, 6.2 times (95% CI 1.3-29.7) among those infected with HIV, and 1.8 times (95% CI 1.1-2.9) among those diagnosed outside district DMC.Conclusion
Delay in initiation of TB treatment occurred in majority of the smear-positive patients. The RNTCP should focus on core areas of providing quality TB services with time-tested strategies. To have real-time monitoring mechanisms for diagnosed smear-positive TB patients is expected to be the way forward. 相似文献128.
Deepak P. Edward Hind Alkatan Qundeel Rafiq Charles Eberhart Saleh Al Mesfer Nicola Ghazi Leen Al Safieh Altaf A. Kondkar Khaled K. Abu Amero 《PloS one》2015,10(3)
Purpose
To study the differential expression of microRNA (miRNA) profiles between intraocular medulloepithelioma (ME) and normal control tissue (CT).Material and Methods
Total RNA was extracted from formalin fixed paraffin embedded (FFPE) intraocular ME (n=7) and from age matched ciliary body controls (n=8). The clinical history and phenotype was recorded. MiRNA profiles were determined using the Affymetrix GeneChip miRNA Arrays analyzed using expression console 1.3 software. Validation of significantly dysregulated miRNA was confimed by quantitaive real-time PCR. The web-based DNA Intelligent Analysis (DIANA)-miRPath v2.0 was used to perform enrichment analysis of differentially expressed (DE) miRNA gene targets in Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway.Results
The pathologic evaluation revealed one benign (benign non-teratoid, n=1) and six malignant tumors (malignant teratoid, n=2; malignant non-teratoid, n = 4). A total of 88 miRNAs were upregulated and 43 miRNAs were downregulated significantly (P<0.05) in the tumor specimens. Many of these significantly dysregulated miRNAs were known to play various roles in carcinogenesis and tumor behavior. RT-PCR validated three significantly upregulated miRNAs and three significantly downregulated miRNAs namely miR-217, miR-216a, miR-216b, miR-146a, miR-509-3p and miR-211. Many DE miRNAs that were significant in ME tumors showed dysregulation in retinoblastoma, glioblastoma, and precursor, normal and reactive human cartilage. Enriched pathway analysis suggested a significant association of upregulated miRNAs with 15 pathways involved in prion disease and several types of cancer. The pathways involving significantly downregulated miRNAs included the toll-like receptor (TLR) (p<4.36E-16) and Nuclear Factor kappa B (NF-κB) signaling pathways (p<9.00E-06).Conclusions
We report significantly dysregulated miRNAs in intraocular ME tumors, which exhibited abnormal profiles in other cancers as well such as retinoblastoma and glioblastoma. Pathway analysis of all dysregulated miRNAs shared commonalities with other cancer pathways. 相似文献129.
130.
Biswajit Brahma Sushil Kumar Bidhan Chandra De Purusottam Mishra Mahesh Chandra Patra Deepak Gaur Meenu Chopra Devika Gautam Sourav Mahanty Hrudananda Malik Dhruba Malakar Tirtha Kumar Datta Sachinandan De 《PloS one》2015,10(3)
Nucleotide binding and oligomerization domain (NOD)-like receptors (NLRs) are innate immune receptors that recognize bacterial cell wall components and initiate host immune response. Structure and function of NLRs have been well studied in human and mice, but little information exists on genetic composition and role of these receptors in innate immune system of water buffalo—a species known for its exceptional disease resistance. Here, a comparative study on the functional domains of NOD1 and NOD2 was performed across different species. The NOD mediated in-vitro cellular responses were studied in buffalo peripheral blood mononuclear cells, resident macrophages, mammary epithelial, and fibroblast cells. Buffalo NOD1 (buNOD1) and buNOD2 showed conserved domain architectures as found in other mammals. The domains of buNOD1 and buNOD2 showed analogy in secondary and tertiary conformations. Constitutive expressions of NODs were ubiquitous in different tissues. Following treatment with NOD agonists, peripheral lymphocytes showed an IFN-γ response along-with production of pro-inflammatory cytokines. Alveolar macrophages and mammary epithelial cells showed NOD mediated in-vitro immune response through NF-κB dependent pathway. Fibroblasts showed pro-inflammatory cytokine response following agonist treatment. Our study demonstrates that both immune and non-immune cells could generate NOD-mediated responses to pathogens though the type and magnitude of response depend on the cell types. The structural basis of ligand recognition by buffalo NODs and knowledge of immune response by different cell types could be useful for development of non-infective innate immune modulators and next generation anti-inflammatory compounds. 相似文献