全文获取类型
收费全文 | 1418篇 |
免费 | 114篇 |
国内免费 | 2篇 |
出版年
2023年 | 15篇 |
2022年 | 21篇 |
2021年 | 64篇 |
2020年 | 31篇 |
2019年 | 32篇 |
2018年 | 47篇 |
2017年 | 51篇 |
2016年 | 63篇 |
2015年 | 67篇 |
2014年 | 74篇 |
2013年 | 125篇 |
2012年 | 128篇 |
2011年 | 120篇 |
2010年 | 65篇 |
2009年 | 50篇 |
2008年 | 73篇 |
2007年 | 57篇 |
2006年 | 63篇 |
2005年 | 61篇 |
2004年 | 45篇 |
2003年 | 32篇 |
2002年 | 29篇 |
2001年 | 19篇 |
2000年 | 11篇 |
1999年 | 17篇 |
1998年 | 9篇 |
1997年 | 4篇 |
1995年 | 5篇 |
1994年 | 4篇 |
1992年 | 7篇 |
1991年 | 4篇 |
1990年 | 7篇 |
1989年 | 8篇 |
1988年 | 8篇 |
1987年 | 5篇 |
1986年 | 8篇 |
1985年 | 8篇 |
1984年 | 4篇 |
1983年 | 8篇 |
1982年 | 5篇 |
1981年 | 6篇 |
1980年 | 11篇 |
1979年 | 10篇 |
1977年 | 4篇 |
1974年 | 4篇 |
1973年 | 5篇 |
1971年 | 5篇 |
1970年 | 3篇 |
1969年 | 6篇 |
1966年 | 4篇 |
排序方式: 共有1534条查询结果,搜索用时 15 毫秒
81.
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
82.
Mi Ryung Roh Philip Eliades Sameer Gupta Hensin Tsao 《Pigment cell & melanoma research》2015,28(6):661-672
Melanocytic nevi are a benign clonal proliferation of cells expressing the melanocytic phenotype, with heterogeneous clinical and molecular characteristics. In this review, we discuss the genetics of nevi by salient nevi subtypes: congenital melanocytic nevi, acquired melanocytic nevi, blue nevi, and Spitz nevi. While the molecular etiology of nevi has been less thoroughly studied than melanoma, it is clear that nevi and melanoma share common driver mutations. Acquired melanocytic nevi harbor oncogenic mutations in BRAF, which is the predominant oncogene associated with melanoma. Congenital melanocytic nevi and blue nevi frequently harbor NRAS mutations and GNAQ mutations, respectively, while Spitz and atypical Spitz tumors often exhibit HRAS and kinase rearrangements. These initial ‘driver’ mutations are thought to trigger the establishment of benign nevi. After this initial phase of the cell proliferation, a senescence program is executed, causing termination of nevi growth. Only upon the emergence of additional tumorigenic alterations, which may provide an escape from oncogene‐induced senescence, can malignant progression occur. Here, we review the current literature on the pathobiology and genetics of nevi in the hope that additional studies of nevi promise to inform our understanding of the transition from benign neoplasm to malignancy. 相似文献
83.
This paper is about how cortical recurrent interactions in primary visual cortex (V1) together with feedback from extrastriate
cortex can account for spectral peaks in the V1 local field potential (LFP). Recent studies showed that visual stimulation
enhances the γ-band (25–90 Hz) of the LFP power spectrum in macaque V1. The height and location of the γ-band peak in the LFP spectrum were correlated with visual stimulus size. Extensive spatial summation, possibly mediated by
feedback connections from extrastriate cortex and long-range horizontal connections in V1, must play a crucial role in the
size dependence of the LFP. To analyze stimulus-effects on the LFP of V1 cortex, we propose a network model for the visual
cortex that includes two populations of V1 neurons, excitatory and inhibitory, and also includes feedback to V1 from extrastriate
cortex. The neural network model for V1 was a resonant system. The model’s resonance frequency (ResF) was in the γ-band and varied up or down in frequency depending on cortical feedback. The model’s ResF shifted downward with stimulus size,
as in the real cortex, because increased size recruited more activity in extrastriate cortex and V1 thereby causing stronger
feedback. The model needed to have strong local recurrent inhibition within V1 to obtain ResFs that agree with cortical data.
Network resonance as a consequence of recurrent excitation and inhibition appears to be a likely explanation for γ-band peaks in the LFP power spectrum of the primary visual cortex. 相似文献
84.
B. Santhosh Kumar Santosh K. Tiwari R. Saikant G. Manoj Amit Kunwar G. Sivaram Zakia Abid Adeel Ahmad K. Indira Priyadarsini Aleem A. Khan 《Journal of trace elements in medicine and biology》2010,24(4):263-270
Aim of the present study was to evaluate in vitro toxicity and in vivo antibacterial, anti-inflammatory, antiulcer, and antioxidant activities of two organoselenium compounds, selenocystine (SeCys) and ebselen (Ebs). The study was conducted in experimentally induced ulcers in rodent model infected with Helicobacter pylori (H. pylori). In vitro toxicological studies on normal spleenic lymphocytes revealed that SeCys and Ebs were non-toxic to the cells even at 100 μM concentration. Antibacterial activity was observed at 500 μg/mL concentration of either of the compounds against H. pylori. In vivo studies after treatment with SeCys and Ebs (500 μg/kg/day) resulted in significant reduction in ROS production and inhibition of lipid peroxidation in gastric tissue. The antioxidant and anti-inflammatory activities of both the compounds were also confirmed by their ability to lower GSH reduction, to induce the expression of antioxidant genes such as GPx-4, and MnSOD and to suppress inflammatory genes namely COX-2, TNF-α and TGF-β. In addition, the immunomodulatory activity of both the compounds was evident by enhance of the CD4 levels and maintenance of the IgG, IL-6 and IL-10 levels. Persistent treatment (500 μg/kg, for 28 days) with both the compounds showed considerable (p < 0.05) ulcer healing property supporting its role in gastro protection. In conclusion, the results of our study suggest that both SeCys and Ebs possess broad spectrum of activities without any potential toxicity. 相似文献
85.
Jagesh K. Tiwari Poonam D. Sarkar SK. Pandey Jai Gopal S. Raj Kumar 《Plant Cell, Tissue and Organ Culture》2010,103(2):175-187
Interspecific potato somatic hybrids between Solanum tuberosum L. (di)haploid C-13 and 1 endosperm balance number non-tuberous wild species S. etuberosum Lindl. were produced by protoplasts electrofusion. The objective was to transfer virus resistance from this wild species
into the cultivated potatoes. Post-fusion products were cultured in VKM medium followed by regeneration of calli in MS13 K medium at 20°C under a 16-h photoperiod, and regenerants were multiplied on MS medium. Twenty-one somatic hybrids were
confirmed by RAPD, SSR and cytoplasm (chloroplast/mitochondria) type analysis possessing species-specific diagnostic bands
of corresponding parents. Tetraploid nature of these somatic hybrids was determined through flow cytometry analysis. Somatic
hybrids showed intermediate phenotypes (plant, leaves and floral morphology) to their parents in glass-house grown plants.
All the somatic hybrids were male-fertile. ELISA assay of somatic hybrids after artificial inoculation of Potato virus Y (PVY)
infection reveals high PVY resistance. 相似文献
86.
87.
88.
Sindhuja Sundaram Prabhakar Tiwari Shalini Saini Rajiv Kant Joseph Alex Davis Sudhir Sahdev Kulvinder Singh Saini 《Molecular Biology》2010,44(3):473-478
Protein tyrosine phosphatases (PTPs) play multiple roles in many physiological processes. Over-expression of the PTPs has been shown to be associated with cellular toxicity, which may also lead to the deletion of the respective gene from stable cell clones. We also observed that PTP-1B over-expression in CHO and HEK293 stable cell clones led to cytotoxicity and low revival rates during clone generation and maintenance. To address these issues, bacmid transposition technology was utilized to generate recombinant PTP-1B baculovirus, and Spodoptera frugiperda (Sf9 and Sf21) insect cell lines were infected with the virus. The data obtained on expression and activity of the PTP-1B highlights clear advantage of the recombinant baculovi-rus-insect cell expression system over the mammalian cell line technique due to increase in enzyme activity, strongly inhibited by phosphatase specific inhibitor RK682. Possible application of the expression system for producing active enzymes in bulk quantity for a new drug discovery is also discussed. 相似文献
89.
90.