全文获取类型
收费全文 | 2009篇 |
免费 | 107篇 |
出版年
2023年 | 3篇 |
2022年 | 14篇 |
2021年 | 51篇 |
2020年 | 16篇 |
2019年 | 33篇 |
2018年 | 46篇 |
2017年 | 49篇 |
2016年 | 55篇 |
2015年 | 88篇 |
2014年 | 92篇 |
2013年 | 130篇 |
2012年 | 124篇 |
2011年 | 134篇 |
2010年 | 87篇 |
2009年 | 96篇 |
2008年 | 126篇 |
2007年 | 119篇 |
2006年 | 113篇 |
2005年 | 83篇 |
2004年 | 87篇 |
2003年 | 105篇 |
2002年 | 88篇 |
2001年 | 28篇 |
2000年 | 36篇 |
1999年 | 50篇 |
1998年 | 15篇 |
1997年 | 16篇 |
1996年 | 19篇 |
1995年 | 8篇 |
1994年 | 12篇 |
1993年 | 10篇 |
1992年 | 29篇 |
1991年 | 17篇 |
1990年 | 26篇 |
1989年 | 14篇 |
1988年 | 13篇 |
1987年 | 9篇 |
1986年 | 9篇 |
1985年 | 12篇 |
1984年 | 11篇 |
1983年 | 10篇 |
1982年 | 5篇 |
1981年 | 4篇 |
1980年 | 5篇 |
1979年 | 2篇 |
1977年 | 2篇 |
1976年 | 3篇 |
1975年 | 2篇 |
1974年 | 3篇 |
1973年 | 2篇 |
排序方式: 共有2116条查询结果,搜索用时 15 毫秒
81.
Kazuki Yamamoto Akira Katsuyama Satoshi Ichikawa 《Bioorganic & medicinal chemistry》2019,27(8):1714-1719
Elucidating a structure-activity relationship study by evaluating a series of truncated analogues is a simple but important and effective tactic in medicinal chemistry based on natural products with a large and complex chemical structure. In this study, a series of truncated analogues of tunicamycin V were designed and synthesized and their MraY inhibitory activity was investigated in order to gain insight into the effect of these moieties on MraY inhibition. 相似文献
82.
Takefumi Yamashita Eiichi Mizohata Satoru Nagatoishi Takahiro Watanabe Makoto Nakakido Hiroko Iwanari Yasuhiro Mochizuki Taisuke Nakayama Yuji Kado Yuki Yokota Hiroyoshi Matsumura Takeshi Kawamura Tatsuhiko Kodama Takao Hamakubo Tsuyoshi Inoue Hideaki Fujitani Kouhei Tsumoto 《Structure (London, England : 1993)》2019,27(3):519-527.e5
83.
Yukie Sato Yoshiaki Tsuda Hironori Sakamoto Martijn Egas Tetsuo Gotoh Yutaka Saito Yan‐Xuan Zhang Jian‐Zhen Lin Jung‐Tai Chao Atsushi Mochizuki 《Ecology and evolution》2019,9(4):1590-1602
When males fight for access to females, such conflict rarely escalates into lethal fight because the risks and costs involved, that is, severe injury or death, are too high. The social spider mite, Stigmaeopsis miscanthi, does exhibit lethal male fights, and this male–male aggressiveness varies among populations. To understand the evolution of lethal fighting, we investigated aggressiveness in 42 populations and phylogenetic relationships in 47 populations along the Japanese archipelago. By analysis of the male weapon morph, a proxy for aggressiveness, we confirmed the existence of a mildly aggressive (ML) form, besides the low aggression (LW) and high aggression (HG) forms reported earlier. To evaluate demographic history of these three forms, we employed the approximate Bayesian computation approach using mtCOI sequences and taking into consideration the postlast glacial expansion history of the host plant, Miscanthus sinensis. As results, hierarchical split models are more likely to explain the observed genetic pattern than admixture models, and the ML form in the subtropical region was considered the ancestral group. The inferred demographic history was consistent with the one reconstructed for the host plant in a previous study. The LW form was split from the ML form during the last glacial period (20,000–40,000 years BP), and subsequently, the HG form was split from the ML form at the end of or after the last glacial period (5,494–10,988 years BP). The results also suggest that the mite invaded Japan more than once, resulting in the present parapatric distribution of LW and HG forms in eastern Japan. 相似文献
84.
Kazuki Yoshida Sachiyo Sanada‐Morimura Shou‐Horng Huang Makoto Tokuda 《Ecology and evolution》2019,9(14):8214-8224
The small brown planthopper Laodelphax striatellus (Hemiptera: Delphacidae) is reported to have the endosymbiont Wolbachia, which shows a strong cytoplasmic incompatibility (CI) between infected males and uninfected females. In the 2000s, female‐biased L. striatellus populations were found in Taiwan, and this sex ratio distortion was the result of male‐killing induced by the infection of another endosymbiont, Spiroplasma. Spiroplasma infection is considered to negatively affect both L. striatellus and Wolbachia because the male‐killing halves the offspring of L. striatellus and hinders the spread of Wolbachia infection via CI. Spiroplasma could have traits that increase the fitness of infected L. striatellus and/or coexisting organisms because the coinfection rates of Wolbachia and Spiroplasma were rather high in some areas. In this study, we investigated the influences of the infection of these two endosymbionts on the development, reproduction, and insecticide resistance of L. striatellus in the laboratory. Our results show that the single‐infection state of Spiroplasma had a negative influence on the fertility of L. striatellus, while the double‐infection state had no significant influence. At late nymphal and adult stages, the abundance of Spiroplasma was lower in the double‐infection state than in the single‐infection state. In the double‐infection state, the reduction of Spiroplasma density may be caused by competition between the two endosymbionts, and the negative influence of Spiroplasma on the fertility of host may be relieved. The resistance of L. striatellus to four insecticides was compared among different infection states of endosymbionts, but Spiroplasma infection did not contribute to increase insecticide resistance. Because positive influences of Spiroplasma infection were not found in terms of the development, reproduction, and insecticide resistance of L. striatellus, other factors improving the fitness of Spiroplasma‐infected L. striatellus may be related to the high frequency of double infection in some L. striatellus populations. 相似文献
85.
Aboveground forest structure, biomass, and primary productivity in a tropical heath forest in Central Kalimantan (Indonesian Borneo) were examined using data from 1-ha plots and stand-level allometric equations developed from harvested tree samples. The study site experienced a severe drought in 1997–1998 associated with the El Niño Southern Oscillation event. The drought effect on heath forest productivity was also assessed by evaluating changes in wood mass increment rates. Allometric relationships suggested that heath forest trees had leaves with smaller specific leaf area (SLA), and large heath forest trees allocate more to leaf mass compared to mixed dipterocarp forest trees. Aboveground biomass (for trees ≥ 4.8 cm DBH) in two 1-ha plots, P1 and P4, totaled 244.8 and 232.0 Mg/ha. Aboveground wood mass increment rate was –0.1 and 4.7 Mg/ha/yr in P1 and P4 during the drought period (from February to August 1998), while it quickly recovered to 8.1 and 8.5 Mg/ha/yr during the post-drought period (from August 1998 to August 1999 for P1 and from August 1998 to November 1999 for P4). This suggests a severe impact of the drought on heath forest productivity. Leaf characteristics of heath forest such as small SLA and long-lived leaves probably play a significant role in effective assimilation and maintenance of heath forest productivity under stressful conditions. 相似文献
86.
87.
Takeshi Kikko Daisuke Ishizaki Taiga Yodo Shizuo Aino Kunihiko Kuwamura Haruo Okamoto Morihito Nemoto Kazuki Yoneda Nobuyuki Oue Akihisa Sakai Yasuhiro Fujioka Yoshiaki Kai Takuya Sato Kouji Nakayama 《Journal of fish biology》2019,95(2):668-672
Otolith growth increments in wild-caught alizarin complex one (ALC)-marked honmoroko Gnathopogon caerulescens were examined to verify the veracity of the age determination method in cyprinids. ALC-marked G. caerulescens recaptured from their natural environment had lapilli increment counts outside the ALC ring mark that had formed on a daily basis during the juvenile stage. This apparently being the first direct evidence of daily periodicity of otolith increment formation in wild-caught cyprinids. 相似文献
88.
Ando Shiori Funato Michinori Ohuchi Kazuki Inagaki Satoshi Sato Arisu Seki Junko Kawase Chizuru Saito Toshio Nishio Hisahide Nakamura Shinsuke Shimazawa Masamitsu Kaneko Hideo Hara Hideaki 《Neurochemical research》2019,44(7):1773-1779
Neurochemical Research - Spinal muscular atrophy (SMA) is an inherited disease characterized by progressive motor neuron death and subsequent muscle weakness and is caused by deletion or mutation... 相似文献
89.
Hiroshi Sato Hiroshi Mochizuki Yuki Tomita Toshio Izako Naofumi Sato Toshinori Kanamori 《Luminescence》1996,11(1):23-29
We have compared three competitive chemiluminescent immunoassays (CLIA) for estradiol (E2) using an N-functionalized acridinium ester (AE). The assays were a standard competitive assay using immobilized antibody and directly labeled antigen (type A), an immobilized antibody and indirectly labeled antigen (type B), and an immobilized antigen and labeled antibody (type C). In an antibody-immobilized system, the assay using both AE- and E2-labeled thyroglobulin as a tracer (type B) was more sensitive than that using AE directly coupled with E2 (type A). Subsequently, a comparison of the antibody-immobilized system (type B) and an antigen-immobilized system (type C) showed that the latter was slightly more sensitive than the former. The sensitivity of the CLIA (type C) was similar or superior to commercially available CLIA or radioimmunoassays for E2. Thus, the N-functionalized AE proved to be a useful labeling reagent for a competitive CLIA with high sensitivity. 相似文献
90.
Ferroptosis is an iron-dependent mode of cell death caused by excessive oxidative damage to lipids. Lipid peroxidation is normally suppressed by glutathione peroxidase 4, which requires reduced glutathione. Cystine is a major resource for glutathione synthesis, especially in cancer cells. Therefore, cystine deprivation or inhibition of cystine uptake promotes ferroptosis in cancer cells. However, the roles of other molecules involved in cysteine deprivation–induced ferroptosis are unexplored. We report here that the expression of gamma-glutamyltransferase 1 (GGT1), an enzyme that cleaves extracellular glutathione, determines the sensitivity of glioblastoma cells to cystine deprivation–induced ferroptosis at high cell density (HD). In glioblastoma cells expressing GGT1, pharmacological inhibition or deletion of GGT1 suppressed the cell density–induced increase in intracellular glutathione levels and cell viability under cystine deprivation, which were restored by the addition of cysteinylglycine, the GGT product of glutathione cleavage. On the other hand, cystine deprivation induced glutathione depletion and ferroptosis in GGT1-deficient glioblastoma cells even at an HD. Exogenous expression of GGT1 in GGT1-deficient glioblastoma cells inhibited cystine deprivation–induced glutathione depletion and ferroptosis at an HD. This suggests that GGT1 plays an important role in glioblastoma cell survival under cystine-limited and HD conditions. We conclude that combining GGT inhibitors with ferroptosis inducers may provide an effective therapeutic approach for treating glioblastoma. 相似文献