全文获取类型
收费全文 | 2146篇 |
免费 | 128篇 |
出版年
2023年 | 14篇 |
2022年 | 28篇 |
2021年 | 39篇 |
2020年 | 34篇 |
2019年 | 28篇 |
2018年 | 66篇 |
2017年 | 38篇 |
2016年 | 59篇 |
2015年 | 101篇 |
2014年 | 99篇 |
2013年 | 142篇 |
2012年 | 174篇 |
2011年 | 130篇 |
2010年 | 75篇 |
2009年 | 74篇 |
2008年 | 97篇 |
2007年 | 115篇 |
2006年 | 104篇 |
2005年 | 88篇 |
2004年 | 79篇 |
2003年 | 59篇 |
2002年 | 58篇 |
2001年 | 50篇 |
2000年 | 40篇 |
1999年 | 26篇 |
1998年 | 26篇 |
1997年 | 19篇 |
1996年 | 10篇 |
1995年 | 19篇 |
1994年 | 10篇 |
1992年 | 25篇 |
1991年 | 35篇 |
1990年 | 20篇 |
1989年 | 10篇 |
1988年 | 20篇 |
1987年 | 26篇 |
1986年 | 21篇 |
1985年 | 21篇 |
1984年 | 21篇 |
1983年 | 11篇 |
1982年 | 13篇 |
1981年 | 11篇 |
1979年 | 18篇 |
1978年 | 9篇 |
1977年 | 9篇 |
1976年 | 10篇 |
1975年 | 17篇 |
1974年 | 11篇 |
1973年 | 10篇 |
1968年 | 7篇 |
排序方式: 共有2274条查询结果,搜索用时 15 毫秒
81.
Saikia Snigdha Pal Uttariya Kalita Deep Jyoti Rai Avdhesh Kumar Sarma Anupam Kataki Amal Chandra Limaye Anil Mukund 《Molecular biology reports》2021,48(7):5399-5409
Molecular Biology Reports - RUNX1T1 is extensively studied in the context of AML1-RUNX1T1 fusion protein in acute myeloid leukemia. Little is known about the function of RUNX1T1 itself, although... 相似文献
82.
83.
Ajantaa Pal Swasti S. Swain Anath B. Das Arup K. Mukherjee Pradeep K. Chand 《In vitro cellular & developmental biology. Plant》2013,49(2):114-128
We have optimized a procedure for genetic transformation of a major leafy vegetable crop, Amaranthus tricolor L., using epicotyl explant co-cultivation with Agrobacterium tumefaciens. Two disarmed A. tumefaciens strains EHA 105 and LBA 4404, both carrying the binary plasmid p35SGUSINT harboring the neomycin phosphotransferase II gene (nptII) and the β-glucuronidase gene (gus), were evaluated as vector systems. The former displayed a higher transforming efficiency. Several key factors influencing the transformation events were optimized. The highest percentage of transformed shoots (24.24%) was achieved using hand-pricked epicotyl explants, a 10-min infection period, with 100 μM acetosyringone-pretreated Agrobacterium culture corresponding to OD600???0.6 and diluted to 109 cells ml?1, followed by 4 d co-cultivation in the regeneration medium. Putative transformed explants capable of forming shoots were selected on medium supplemented with 75 μg?ml?1 kanamycin, and transient as well as stable glucuronidase expression was determined by histochemical analysis. From a total of 48 selected shoot lines derived from independent transformation events with epicotyl explants co-cultivated with EHA 105, 32 showed positive PCR amplification for both the nptII and gus genes. Germ line transformation and transgene stability were evident in progeny of primary transformed plants (T0). Among T1 seedlings of 12 selected transgenic plant lines, kanamycin-resistant and kanamycin-sensitive seedlings segregated in a ratio typical of the Mendelian monohybrid pattern (3:1) as verified by the chi-square (χ 2) test. Southern hybridization of genomic DNA from kanamycin-resistant T1 transgenic segregants to an nptII probe substantiated stable integration of the transgene. Neomycin phosphotransferase (NPTII) activity was detected in leaf protein extracts of selected T1 transgenic plants, thereby confirming stable expression of the nptII gene. 相似文献
84.
I. N. Bolotov A. A. Makhrov Yu. V. Bespalaya I. V. Vikhrev O. V. Aksenova P. E. Aspholm M. Yu. Gofarov A. N. Ostrovskii I. Yu. Popov I. S. Pal’tser M. Rudzite M. Rudzitis I. S. Voroshilova S. E. Sokolova 《Biology Bulletin》2013,40(2):221-231
This paper continues a discussion on the number of pearl mussel species of the genus Margaritifera in northern Europe. A biometric study of 1711 pearl mussel Margaritifera margaritifera shells from 15 rivers in Russia and Latvia (basins of the White and Baltic seas) has been conducted. All the examined samples fall into two groups: the northern group (with the shells more flattened on average, f. margaritifera) and the southern one (with more convex shells, f. elongata); the boundary between these groups is at 63° N. Analysis of intrapopulation variation has shown that the samples contain individuals that correspond to f. margaritifera, f. elongata, and f. borealis. However, any hiatus between these forms is absent in all the samples, and individuals belonging to two intermediate forms are rather frequent. The hypothesis on the species specificity of the shell valve frontal section has not been confirmed based on examination of large shell samples. The pearl mussels inhabiting rivers of Northern Europe belong to a single species, M. margaritifera. 相似文献
85.
86.
87.
88.
Harish Chandra Pal Samriti Sharma Leah Ray Strickland Jyoti Agarwal Mohammad Athar Craig A. Elmets Farrukh Afaq 《PloS one》2013,8(10)
Epidermal growth factor receptor (EGFR) and vascular endothelial growth factor receptor 2 (VEGFR2) have emerged as two effective clinical targets for non-small-cell lung cancer (NSCLC). In the present study, we found that delphinidin, an anthocyanidin, present in pigmented fruits and vegetables, is a potent inhibitor of both EGFR and VEGFR2 in NSCLC cells that overexpress EGFR/VEGFR2. Using these cells, we next determined the effects of delphinidin on cell growth and apoptosis in vitro and on tumor growth and angiogenesis in vivo. Delphinidin (5-60 µM) treatment of NSCLC cells inhibited the activation of PI3K, and phosphorylation of AKT and MAPKs. Additionally, treatment of NSCLC cells with delphinidin resulted in inhibition of cell growth without having significant toxic effects on normal human bronchial epithelial cells. Specifically, treatment of NCI-H441 and SK-MES-1 cells with delphindin (5-60 µM) resulted in (i) cleavage of PARP protein, (ii) activation of caspase-3 and -9, (iii) downregulation of anti-apoptotic proteins (Bcl2, Bcl-xL and Mcl-1), (iv) upregulation of pro-apoptotic proteins (Bax and Bak), and (v) decreased expression of PCNA and cyclin D1. Furthermore, in athymic nude mice subcutaneously implanted with human NSCLC cells, delphinidin treatment caused a (i) significant inhibition of tumor growth, (ii) decrease in the expression of markers for cell proliferation (Ki67 and PCNA) and angiogenesis (CD31 and VEGF), and (iii) induction of apoptosis, when compared with control mice. Based on these observations, we suggest that delphinidin, alone or as an adjuvant to current therapies, could be used for the management of NSCLC, especially those that overexpress EGFR and VEGFR2. 相似文献
89.
90.
Many attempts on optimization of sorghum [Sorghum bicolor (L.)
Moench] tissue culture induction media have been made, but the culture system
remains with some bottlenecks compared to that of other crops. This study aimed
at assessing the suitability of various induction media to produce embryogenic
callus (yellow and friable) with high induction rates and reduced phenolic
exudation. The six culture medium modifications: 3 based on Murashige and
Skoog (MS) medium and one each based on Chu N6, Gamborg B5 and 190-2
media respectively were applied in the culture of mature embryos from 10
sorghum genotypes. Although there was a genotype influence on the attainment
of a yellow callus, friability of the callus was determined to be dependent on the
culture medium and not the genotype. Half strength MS medium with 0.2 mg/l
2,4-D with 2.8 g/l Gelrite® as the gelling agent modified with 1.0 g/l KH2PO4,
1.0 g/l L-proline, 1.0 g/l L-asparagine and 0.16 mg/l CuSO4·5H2O (type E) was
found to be the most effective resulting in about 60% yellow coloured callus
induction with 25% friability. Addition of CuSO4·5H2O, KH2PO4, L-proline and
L-asparagine significantly reduced the phenolic production. Half strength MS
medium was observed to contribute to quality callus production when compared
to full strength MS media modified with the compounds. The half strength MS
medium was also observed to suppress phenolic production. Medium 190-2
produced the highest regeneration frequency (40%) among the 3-regeneration
media tested. The results provide information on a suitable sorghum callus
induction medium necessary for embryogenesis. 相似文献