全文获取类型
收费全文 | 105225篇 |
免费 | 9082篇 |
国内免费 | 7023篇 |
出版年
2024年 | 158篇 |
2023年 | 1084篇 |
2022年 | 2405篇 |
2021年 | 4545篇 |
2020年 | 3031篇 |
2019年 | 3713篇 |
2018年 | 3725篇 |
2017年 | 2670篇 |
2016年 | 3796篇 |
2015年 | 6037篇 |
2014年 | 6962篇 |
2013年 | 7815篇 |
2012年 | 9167篇 |
2011年 | 8527篇 |
2010年 | 5196篇 |
2009年 | 4585篇 |
2008年 | 5606篇 |
2007年 | 4997篇 |
2006年 | 4394篇 |
2005年 | 3717篇 |
2004年 | 3249篇 |
2003年 | 2834篇 |
2002年 | 2512篇 |
2001年 | 2196篇 |
2000年 | 2139篇 |
1999年 | 1965篇 |
1998年 | 1132篇 |
1997年 | 1063篇 |
1996年 | 1073篇 |
1995年 | 943篇 |
1994年 | 926篇 |
1993年 | 692篇 |
1992年 | 1115篇 |
1991年 | 932篇 |
1990年 | 833篇 |
1989年 | 750篇 |
1988年 | 599篇 |
1987年 | 507篇 |
1986年 | 476篇 |
1985年 | 443篇 |
1984年 | 354篇 |
1983年 | 293篇 |
1982年 | 197篇 |
1981年 | 172篇 |
1979年 | 222篇 |
1978年 | 154篇 |
1977年 | 148篇 |
1976年 | 146篇 |
1975年 | 168篇 |
1974年 | 185篇 |
排序方式: 共有10000条查询结果,搜索用时 203 毫秒
171.
Ralstonia solanacearum (RS) race 1 biovar 4 (R1bv4), causal agent of bacterial wilt in vegetable sweet potato (VSP), is often latent in VSP vines and is important in introduction of the pathogen to newly planted fields. In this study, the effects of biological and environmental factors on the distribution and multiplication of R1bv4 in VSP tissues were examined. Based on stem-injection inoculation, the R1bv4strain of NC01 could cause 49.0% and 33.0% wilting on VSP cultivars TN71 and WS, respectively. The populations of NC01 in diseased TN71 and WS were 108–109 cfu/g tissue at 28th day after inoculation. On the other hand, the R1bv4 could not cause symptom in cultivars of TN57 and VSPSL-1 vine and the NC01 was confined to near the injection sites. Temperature tests indicated that NC01 could cause 28.0% and 14.0% wilting on cultivar TN71 at 28 and 20°C, respectively. Moreover, the populations of NC01in diseased plants were 1.6 × 109 and 7.9 × 108 cfu/g tissue at 28 and 20°C, respectively. The distribution of NC01 in VSP stem indicated that the isolation frequency of NC01 was lower than 31.0% in terminal shoots or erect stems and 45.0 to 100.0% in creeping stem after 8 wks planted in infested soil (106 cfu/g soil). The results demonstrated that terminal shoots or erect stems were not common carrier for transmitting R1bv4. Furthermore, two R1bv4 strains, NC01 and HsinT01, were examined the ability for latent infection on cv. TN71. The results revealed that NC01 and HsinT01 showed different ability of latent infection on cultivar TN71. NC01 had lower percentage (46.8% and 45.1%) than HsinT01 (93.4% and 75.3%) at 20 and 28°C. 相似文献
172.
Heqiao Zhang Dong-Hua Chen Rayees U.H. Mattoo David A. Bushnell Yannan Wang Chao Yuan Lin Wang Chunnian Wang Ralph E. Davis Yan Nie Roger D. Kornberg 《Molecular cell》2021,81(8):1781-1788.e4
- Download : Download high-res image (174KB)
- Download : Download full-size image
173.
174.
Lin Xiang Lin Shuang Liu Yuanlan Zhao Haiyan Wang Li Hasi Wuliji 《Plasmonics (Norwell, Mass.)》2018,13(5):1749-1758
Plasmonics - Large-scale ordered two-dimensional (2D) superlattices at oil/water interface were fabricated using single-crystal Au nanospheres (NSs) with different diameters as building blocks. A... 相似文献
175.
Shi Fenghua Tan Muxiu Mo Qiaocheng Chen Xiaoying Zhao Yimin Guo Xiaoyun Jiang Ni 《Journal of plant biochemistry and biotechnology.》2020,29(3):528-538
Journal of Plant Biochemistry and Biotechnology - The dried buds of Lonicera hypoglauca Miq. have antipyretic, antidotal and anti-inflammatory properties and as Flos lonicerae are widely used in... 相似文献
176.
177.
178.
179.
Antibodies against the chondroitin sulfate proteoglycan NG2 label a subpopulation of glial cells within the CNS, which have a small cell body and thin radiating processes. Physiological recordings from these small cells in acute brain slices have revealed that they possess unique properties, suggesting that they may comprise a class of glial cells distinct from astrocytes, oligodendrocytes, or microglia. NG2-expressing glial cells (abbreviated as “NG2 cells” here) have a moderate input resistance and are not dye- or tracer-coupled to adjacent cells. They express voltage-gated Na+, K+and Ca2+conductances, though they do not exhibit regenerative Na+or Ca2+action potentials due to the much larger K+conductances present. In addition to voltage-gated conductances, they express receptors for various neurotransmitters. In the hippocampus, AMPA and GABAAreceptors on these cells are activated by release of transmitter from neurons at defined synaptic junctions that are formed with CA3 pyramidal neurons and GABAergic interneurons. These rapid forms of neuron-glial communication may regulate the proliferation rate of NG2 cells or their development into mature oligodendrocytes. These depolarizing inputs may also trigger the release of neuroactive substances from NG2 cells, providing feedback regulation of signaling at neuronal synapses. Although the presence of Ca2+permeable AMPA receptors provides a pathway to link neuronal activity to Ca2+dependent processes within the NG2 cells, these receptors also put these cells at risk for glutamate-associated excitotoxicity. This vulnerability to the sustained elevation of glutamate may underlie ischemic induced damage to white matter tracts and contribute to cerebral palsy in premature infants. 相似文献
180.