全文获取类型
收费全文 | 3431篇 |
免费 | 235篇 |
国内免费 | 250篇 |
专业分类
3916篇 |
出版年
2024年 | 7篇 |
2023年 | 42篇 |
2022年 | 108篇 |
2021年 | 192篇 |
2020年 | 126篇 |
2019年 | 153篇 |
2018年 | 159篇 |
2017年 | 101篇 |
2016年 | 131篇 |
2015年 | 188篇 |
2014年 | 256篇 |
2013年 | 254篇 |
2012年 | 328篇 |
2011年 | 282篇 |
2010年 | 160篇 |
2009年 | 139篇 |
2008年 | 178篇 |
2007年 | 128篇 |
2006年 | 121篇 |
2005年 | 100篇 |
2004年 | 78篇 |
2003年 | 92篇 |
2002年 | 77篇 |
2001年 | 40篇 |
2000年 | 56篇 |
1999年 | 60篇 |
1998年 | 34篇 |
1997年 | 30篇 |
1996年 | 23篇 |
1995年 | 30篇 |
1994年 | 26篇 |
1993年 | 22篇 |
1992年 | 32篇 |
1991年 | 24篇 |
1990年 | 23篇 |
1989年 | 19篇 |
1988年 | 15篇 |
1987年 | 14篇 |
1986年 | 9篇 |
1985年 | 9篇 |
1984年 | 7篇 |
1983年 | 3篇 |
1982年 | 4篇 |
1981年 | 4篇 |
1980年 | 5篇 |
1979年 | 3篇 |
1976年 | 3篇 |
1969年 | 3篇 |
1966年 | 2篇 |
1951年 | 2篇 |
排序方式: 共有3916条查询结果,搜索用时 15 毫秒
191.
Yu?Ni Zhengyuan?Sun Xianzhi?Huang Chuanshu?Huang Yanjun?GuoEmail author 《Acta Physiologiae Plantarum》2015,37(6):112
Though mulberry (Morus alba) tree shows great adaptations to various climate conditions, their leaf water status and photosynthesis are sensitive to climate changes. In the current study, seven widely planted mulberry cultivars in Chongqing, Southwest China, were selected to analyze leaf cuticular wax characteristics, gas exchange index, post-harvest leaf water status and their relationships, aiming to provide new theory in screening high resistant mulberry cultivars. Mulberry trees formed rounded cap-type idioblasts on the adaxial leaf surface. Film-like waxes and granule-type wax crystals covered leaf surfaces, varying in crystal density among cultivars. The stomatal aperture on the abaxial surface of cultivars with high wax amount was smaller than that of cultivars with low wax amount. The amount of total wax was negatively correlated with the net photosynthetic rate (P N), transpiration rate (E) and stomatal conductance (g s) and positively correlated with the moisture retention capacity. It suggested that both cuticular wax and stomatal factor might be involved in regulating water loss in mulberry leaves under field conditions. The variability in moisture retention capacity and cuticular wax characteristics might be important in evaluating and screening mulberry cultivars for increasing silk quality and silkworm productivity. 相似文献
192.
Xiaodan Ni Joseph H. Davis Nikhil Jain Aida Razi Samir Benlekbir Andrew G. McArthur John L. Rubinstein Robert A. Britton James R. Williamson Joaquin Ortega 《Nucleic acids research》2016,44(17):8442-8455
YphC and YsxC are GTPases in Bacillus subtilis that facilitate the assembly of the 50S ribosomal subunit, however their roles in this process are still uncharacterized. To explore their function, we used strains in which the only copy of the yphC or ysxC genes were under the control of an inducible promoter. Under depletion conditions, they accumulated incomplete ribosomal subunits that we named 45SYphC and 44.5SYsxC particles. Quantitative mass spectrometry analysis and the 5–6 Å resolution cryo-EM maps of the 45SYphC and 44.5SYsxC particles revealed that the two GTPases participate in the maturation of the central protuberance, GTPase associated region and key RNA helices in the A, P and E functional sites of the 50S subunit. We observed that YphC and YsxC bind specifically to the two immature particles, suggesting that they represent either on-pathway intermediates or that their structure has not significantly diverged from that of the actual substrate. These results describe the nature of these immature particles, a widely used tool to study the assembly process of the ribosome. They also provide the first insights into the function of YphC and YsxC in 50S subunit assembly and are consistent with this process occurring through multiple parallel pathways, as it has been described for the 30S subunit. 相似文献
193.
Deep sequencing reveals a novel closterovirus associated with wild rose leaf rosette disease 总被引:1,自引:0,他引:1 下载免费PDF全文
Yan He Zuokun Yang Ni Hong Guoping Wang Guogui Ning Wenxing Xu 《Molecular Plant Pathology》2015,16(5):449-458
A bizarre virus‐like symptom of a leaf rosette formed by dense small leaves on branches of wild roses (Rosa multiflora Thunb.), designated as ‘wild rose leaf rosette disease’ (WRLRD), was observed in China. To investigate the presumed causal virus, a wild rose sample affected by WRLRD was subjected to deep sequencing of small interfering RNAs (siRNAs) for a complete survey of the infecting viruses and viroids. The assembly of siRNAs led to the reconstruction of the complete genomes of three known viruses, namely Apple stem grooving virus (ASGV), Blackberry chlorotic ringspot virus (BCRV) and Prunus necrotic ringspot virus (PNRSV), and of a novel virus provisionally named ‘rose leaf rosette‐associated virus’ (RLRaV). Phylogenetic analysis clearly placed RLRaV alongside members of the genus Closterovirus, family Closteroviridae. Genome organization of RLRaV RNA (17 653 nucleotides) showed 13 open reading frames (ORFs), except ORF1 and the quintuple gene block, most of which showed no significant similarities with known viral proteins, but, instead, had detectable identities to fungal or bacterial proteins. Additional novel molecular features indicated that RLRaV seems to be the most complex virus among the known genus members. To our knowledge, this is the first report of WRLRD and its associated closterovirus, as well as two ilarviruses and one capilovirus, infecting wild roses. Our findings present novel information about the closterovirus and the aetiology of this rose disease which should facilitate its control. More importantly, the novel features of RLRaV help to clarify the molecular and evolutionary features of the closterovirus. 相似文献
194.
195.
196.
Protoplasts were isolated from mesophyll of axenic cultures of grape, Vitis rotundifolia cv. Summit and V. vinifera cv. Cabernet Sauvignon. Enzymes effective for protoplast isolation were Macerozyme R-10 (0.5% and 0.1%) and Cellulase Onozuka R-10 (1.0% and 0.5%) for V. rotundifolia and V. vinifera, respectively. Polyvinylpyrrolidone and 2-(N-morpholino)ethanesulfonic acid were essential in the isolation media. Protoplasts were purified using flotation/centrifugation. The protoplasts of V. rotundifolia cultured in Gamborg's B5 basal medium with 2.2 M 6-benzyladenine, 4.5 M 2,4-dichlorophenoxyacetic acid and 0.4% agarose gave the best plating efficiency of conditions tried in this study. Cell division occurred within 5 to 6 days and visible microcalli developed within one month. After 6 weeks in culture, microcalli transferred to liquid medium exhibited active callus growth. Protoplasts of V. vinifera cultured under these conditions had similar results.Abbreviations MES
2-(N-morpholino)ethanesulfonic acid monohydrate
- PVP
polyvinylpyrrolidone
- PDS
potassium dextran sulfate
- BA
6-benzyladenine
- 2,4-D
2,4-dichlorophenoxyacetic acid
- FDA
fluorescein diacetate 相似文献
197.
Terrestrial origin of bacterial communities in complex boreal freshwater networks 总被引:1,自引:0,他引:1 下载免费PDF全文
Clara Ruiz‐González Juan Pablo Niño‐García Paul A. del Giorgio 《Ecology letters》2015,18(11):1198-1206
Bacteria inhabiting boreal freshwaters are part of metacommunities where local assemblages are often linked by the flow of water in the landscape, yet the resulting spatial structure and the boundaries of the network metacommunity have never been explored. Here, we reconstruct the spatial structure of the bacterial metacommunity in a complex boreal aquatic network by determining the taxonomic composition of bacterial communities along the entire terrestrial/aquatic continuum, including soil and soilwaters, headwater streams, large rivers and lakes. We show that the network metacommunity has a directional spatial structure driven by a common terrestrial origin of aquatic communities, which are numerically dominated by taxa recruited from soils. Local community assembly is driven by variations along the hydrological continuum in the balance between mass effects and species sorting of terrestrial taxa, and seems further influenced by priority effects related to the spatial sequence of entry of soil bacteria into the network. 相似文献
198.
Background
the bone marrow and the intestine are the major sites of ionizing radiation (IR)-induced injury. Our previous study demonstrated that CpG-oligodeoxynucleotide (ODN) treatment mitigated IR-induced bone marrow injury, but its effect on the intestine is not known. In this study, we sought to determine if CpG-ODN have protective effect on IR-induced intestine injury, and if so, to determine the mechanism of its effect.Methods and Findings
Mice were treated with CpG-ODN after IR. The body weight and survival were daily monitored for 30 days consecutively after exposure. The number of surviving intestinal crypt was assessed by the microcolony survival assay. The number and the distribution of proliferating cell in crypt were evaluated by TUNEL assay and BrdU assay. The expression of Bcl-2, Bax and caspase-3 in crypt were analyzed by Immunohistochemistry assay. The findings showed that the treatment for irradiated mice with CpG-ODN diminished body weight loss, improved 30 days survival, enhanced intestinal crypts survival and maintained proliferating cell population and regeneration in crypt. The reason might involve that CpG-ODN up-regulated the expression of Bcl-2 protein and down-regulated the expression of Bax protein and caspase-3 protein.Conclusion
CpG-ODN was effective in protection of IR-induced intestine injury by enhancing intestinal crypts survival and maintaining proliferating cell population and regeneration in crypt. The mechanism might be that CpG-ODN inhibits proliferating cell apoptosis through regulating the expression of apoptosis-related protein, such as Bax, Bcl-2 and caspase-3. 相似文献199.
A vascular bundles specific expressing vector pBAL1 with a promoter AQ630 from rice phenylalanine ammonialyase gene and a gene encoding indoleacetic-lysine synthytase from Pseudomonas syringae subsp. savastanoi was constructed. Affirmed by Southern blotting and RTPCR analysis, the AQ630-iaaL transgenic plants show increasing shoots-regeneration frequency of young stem explants on hormone-free 1/2 MS medium and lower sensibility to IAA when roots were induced from the root explants on the media containing different concentrations of IAA compared to untransformed plants. 相似文献
200.
Xuebing Xu Tong Wu Renjie Lin Shengze Zhu Jie Ji Dandan Jin Mengxiang Huang Wenjie Zheng Wenkai Ni Feng Jiang Shihai Xuan Mingbing Xiao 《Journal of cellular and molecular medicine》2023,27(23):3672-3680
The migrasome is a new organelle discovered by Professor Yu Li in 2015. When cells migrate, the membranous organelles that appear at the end of the retraction fibres are migrasomes. With the migration of cells, the retraction fibres which connect migrasomes and cells finally break. The migrasomes detach from the cell and are released into the extracellular space or directly absorbed by the recipient cell. The cytoplasmic contents are first transported to the migrasome and then released from the cell through the migrasome. This release mechanism, which depends on cell migration, is named ‘migracytosis’. The main components of the migrasome are extracellular vesicles after they leave the cell, which are easy to remind people of the current hot topic of exosomes. Exosomes are extracellular vesicles wrapped by the lipid bimolecular layer. With extensive research, exosomes have solved many disease problems. This review summarizes the differences between migrasomes and exosomes in size, composition, property and function, extraction method and regulation mechanism for generation and release. At the same time, it also prospects for the current hotspot of migrasomes, hoping to provide literature support for further research on the generation and release mechanism of migrasomes and their clinical application in the future. 相似文献