全文获取类型
收费全文 | 10248篇 |
免费 | 1184篇 |
国内免费 | 1075篇 |
出版年
2024年 | 18篇 |
2023年 | 115篇 |
2022年 | 297篇 |
2021年 | 514篇 |
2020年 | 458篇 |
2019年 | 493篇 |
2018年 | 517篇 |
2017年 | 393篇 |
2016年 | 484篇 |
2015年 | 677篇 |
2014年 | 773篇 |
2013年 | 772篇 |
2012年 | 901篇 |
2011年 | 807篇 |
2010年 | 554篇 |
2009年 | 454篇 |
2008年 | 546篇 |
2007年 | 474篇 |
2006年 | 436篇 |
2005年 | 340篇 |
2004年 | 353篇 |
2003年 | 363篇 |
2002年 | 352篇 |
2001年 | 241篇 |
2000年 | 158篇 |
1999年 | 180篇 |
1998年 | 105篇 |
1997年 | 94篇 |
1996年 | 89篇 |
1995年 | 92篇 |
1994年 | 68篇 |
1993年 | 55篇 |
1992年 | 54篇 |
1991年 | 46篇 |
1990年 | 40篇 |
1989年 | 42篇 |
1988年 | 26篇 |
1987年 | 20篇 |
1986年 | 18篇 |
1985年 | 8篇 |
1984年 | 12篇 |
1983年 | 14篇 |
1982年 | 13篇 |
1981年 | 11篇 |
1980年 | 6篇 |
1979年 | 7篇 |
1978年 | 3篇 |
1977年 | 4篇 |
1974年 | 2篇 |
1972年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
Fertile rice plants have been regenerated from protoplasts of two japonica rice varieties (Radon and Baldo) using a protocol
initially developed for plant regeneration from protoplasts of an indica rice. Embryogenic calli were developed from immature
embryos of Radon and Baldo rice on a callus induction medium, and then used to establish cell suspensions. Protoplasts were
isolated from the cell suspensions, and cultured on a Millipore filter placed on a Kao/agarose medium that contained cell
clusters from suspensions of IR52 or IR45. The protoplasts grew vigorously on Kao medium and developed into embryogenic calli
within two to three weeks. Somatic embryo development occurred during a subsequent transfer of the calli to an LS medium for
two to three weeks. The calli were then transferred to MS or N6 plant regeneration medium, and within one to three weeks,
plants regenerated from 21 to 32% of the Radon calli, and 33 to 35% of the Baldo calli. Based upon these results and the previous
success in regenerating an indica variety from protoplasts, this procedure has great promise for regenerating a range of rice
varieties, and probably for regeneration of other monocotyledonous plants from protoplasts 相似文献
132.
Ching-San Chen Tuan-Nan Wen Hsiao-Mei Tuan 《Biochimica et Biophysica Acta (BBA) - Gene Structure and Expression》1982,699(2):92-97
It has been previously shown that Clostridium sticklandii specifically synthesized three readily separable 75Se-labeled tRNAs, designated seleno-tRNAs I, II and III, and the partially purified seleno-tRNA II cochromatographed with l-prolyl-tRNA on DEAE-Sephadex A-50 (Chen, C.S. and Stadtman, T.C. (1980) Proc. Natl. Acad. Sci. U.S.A. 77, 1403–1407). In the present study a highly purified 75Se-labeled tRNA I was obtained by chromatography on benzoylated DEAE-cellulose, DEAE-Sephadex A-50 and Sepharose 4B. The 75Se-labeled tRNA I cochromatographed with an l-valine-accepting species on DEAE-Sephadex A-50 and Sepharose 4B. Addition of a 285-fold molar excess of unlabeled l-valine to the l-valine acceptor activity assay mixture markedly decreased the amount of l-[14C]valine bound to seleno-tRNA I. 相似文献
133.
134.
ZAKβ antagonizes and ameliorates the cardiac hypertrophic and apoptotic effects induced by ZAKα 下载免费PDF全文
Chien‐Yao Fu Wei‐Wen Kuo Tsung‐Jung Ho Su‐Ying Wen Ling‐Chun Lin Yan‐Shen Tseng Hui‐Chuan Hung Vijaya Padma Viswanadha Chih‐Yang Huang 《Cell biochemistry and function》2016,34(8):606-612
ZAK (sterile alpha motif and leucine zipper containing kinase AZK), a serine/threonine kinase with multiple biochemical functions, has been associated with various cell processes, including cell proliferation, cell differentiation, and cardiac hypertrophy. In our previous reports, we found that the activation of ZAKα signaling was critical for cardiac hypertrophy. In this study, we show that the expression of ZAKα activated apoptosis through both a FAS‐dependent pathway and a mitochondria‐dependent pathway by subsequently inducing caspase‐3. ZAKβ, an isoform of ZAKα, is dramatically expressed during cardiac hypertrophy and apoptosis. The interaction between ZAKα and ZAKβ was demonstrated here using immunoprecipitation. The results show that ZAKβ has the ability to diminish the expression level of ZAKα. These findings reveal an inherent regulatory role of ZAKβ to antagonize ZAKα and to subsequently downregulate the cardiac hypertrophy and apoptosis induced by ZAKα. 相似文献
135.
136.
ZHENG LianBin LI YongLan XI HuanJiu YU KeLi LU ShunHua SHI Rui WEN YouFeng BAO JingPing ZHANG XingHua LI YuLing REN Fu XU GuoChang 《中国科学:生命科学英文版》2015,58(2):215-217,1,3
<正>Dear Editor,Shortly after initiating the"Physical Anthropological Research on Han Chinese"research project,we applied uniform sampling methods as well as methods and instruments of measurement to obtain a complete set of measurements of physical anthropological indicators among Han populations across China.Among these measurements,body stature was a key indicator.Currently,there should be reliable 相似文献
137.
H. B. Li W. Yan G. R. Liu S. M. Wen C. J. Liu 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2011,122(2):395-403
Tan spot, caused by Pyrenophora tritici-repentis, is a foliar disease of wheat, and it can inflict serious reduction in grain yield and quality. The bread wheat variety Ernie
was found to be immune to this disease in Australia, and its genetic control was investigated by quantitative trait loci (QTL)
analysis using a doubled haploid population. Eight QTL were identified in this population from three independent trials, and
four of them were derived from the parent Ernie. The most significant QTL was located on chromosome arm 2BS, explaining 38.2,
29.8 and 36.2% of the phenotypic variance, respectively, in these trials. The effects of the 2BS QTL were further validated
in four additional populations. The presence of this single QTL reduced disease severity by between 29.2 and 67.1% with an
average of 50.5%. The significant effects of this QTL and its consistent detection across all the trials with different genetic
backgrounds make it an ideal target for breeding programmes as well as for its further characterization. Data from this study
also showed that neither plant height nor heading date significantly affects tan spot resistance. 相似文献
138.
The NLR (nucleotide-binding domain leucine-rich repeat containing) proteins serve as regulators of inflammatory signaling pathways. NLRX1, a mitochondria-localized NLR protein, has been previously shown to negatively regulate inflammatory cytokine production activated via the MAVS-DDX58 (RIG-I) pathway. The literature also indicates that DDX58 has a negative impact upon autophagy. Consistent with the inhibitory role of NLRX1 on DDX58, our recent study indicates a role of NLRX1 in augmenting virus-induced autophagy. This effect is through its interaction with another mitochondrial protein TUFM (Tu translation elongation factor, mitochondrial, also known as EF-TuMT, COXPD4, and P43). TUFM also reduces DDX58-activated cytokines but augments autophagy. Additionally it interacts with ATG12–ATG5-ATG16L1 to form a molecular complex that modulates autophagy. The work shows that both NLRX1 and TUFM work in concert to reduce cytokine response and augment autophagy. 相似文献
139.
Tuberculosis (TB) disease can be caused by either recent transmission from infectious patients or reactivation of remote latent infection. Spatial dependency (correlation between nearby geographic areas) in tuberculosis incidence is a signature for chains of recent transmission with geographic diffusion. To understand the contribution of recent transmission in the TB endemic in Taiwan, where reactivation has been assumed to be the predominant mode of pathogenesis, we used spatial regression analysis to examine whether there was spatial dependency between the TB incidence in each township and in its neighbors. A total of 90,661 TB cases from 349 townships in 2003–2008 were included in this analysis. After adjusting for the effects of confounding socioeconomic variables, including the percentages of aboriginals and average household income, the results show that the spatial lag parameter remains positively significant (0.43, p<0.001), which indicates that the TB incidences of neighboring townships had an effect on the TB incidence in each township. Townships with substantial spatial spillover effects were mainly located in the northern, western and eastern parts of Taiwan. Spatial dependency implies that recent transmission plays a significant role in the pathogenesis of TB in Taiwan. Therefore, in addition to the current focus on improving the cure rate under directly observed therapy programs, more resource need to be allocated to active case finding in order to break the chain of transmission. 相似文献
140.
Organisms used as model genomics systems are maintained as isogenic strains, yet evidence of sequence differences between independently maintained wild-type stocks has been substantiated by whole-genome resequencing data and strain-specific phenotypes. Sequence differences may arise from replication errors, transposon mobilization, meiotic gene conversion, or environmental or chemical assault on the genome. Low frequency alleles or mutations with modest effects on phenotypes can contribute to natural variation, and it has proven possible for such sequences to become fixed by adapted evolutionary enrichment and identified by resequencing. Our objective was to identify and analyze single locus genetic defects leading to RNAi resistance in isogenic strains of Caenorhabditis elegans. In so doing, we uncovered a mutation that arose de novo in an existing strain, which initially frustrated our phenotypic analysis. We also report experimental, environmental, and genetic conditions that can complicate phenotypic analysis of RNAi pathway defects. These observations highlight the potential for unanticipated mutations, coupled with genetic and environmental phenomena, to enhance or suppress the effects of known mutations and cause variation between wild-type strains. 相似文献