全文获取类型
收费全文 | 3316篇 |
免费 | 243篇 |
专业分类
3559篇 |
出版年
2022年 | 16篇 |
2021年 | 35篇 |
2020年 | 14篇 |
2019年 | 18篇 |
2018年 | 27篇 |
2017年 | 23篇 |
2016年 | 45篇 |
2015年 | 80篇 |
2014年 | 85篇 |
2013年 | 167篇 |
2012年 | 136篇 |
2011年 | 150篇 |
2010年 | 104篇 |
2009年 | 109篇 |
2008年 | 166篇 |
2007年 | 157篇 |
2006年 | 173篇 |
2005年 | 163篇 |
2004年 | 178篇 |
2003年 | 188篇 |
2002年 | 167篇 |
2001年 | 135篇 |
2000年 | 146篇 |
1999年 | 111篇 |
1998年 | 36篇 |
1997年 | 33篇 |
1996年 | 36篇 |
1995年 | 41篇 |
1994年 | 44篇 |
1993年 | 32篇 |
1992年 | 67篇 |
1991年 | 66篇 |
1990年 | 48篇 |
1989年 | 46篇 |
1988年 | 53篇 |
1987年 | 45篇 |
1986年 | 55篇 |
1985年 | 37篇 |
1984年 | 22篇 |
1983年 | 32篇 |
1982年 | 28篇 |
1981年 | 15篇 |
1980年 | 20篇 |
1979年 | 26篇 |
1978年 | 18篇 |
1977年 | 18篇 |
1975年 | 19篇 |
1974年 | 12篇 |
1971年 | 12篇 |
1969年 | 20篇 |
排序方式: 共有3559条查询结果,搜索用时 15 毫秒
41.
Natalia J. Martinez Ganesha Rai Adam Yasgar Wendy A. Lea Hongmao Sun Yuhong Wang Diane K. Luci Shyh-Ming Yang Kana Nishihara Shunichi Takeda Mohiuddin Irina Earnshaw Tetsuya Okada Kazutoshi Mori Kelli Wilson Gregory J. Riggins Menghang Xia Maurizio Grimaldi Ajit Jadhav David J. Maloney Anton Simeonov 《PloS one》2016,11(11)
42.
We studied the effect of GroEL on the kinetic refolding of-lactalbumin by stopped-flow fluorescence techniques. We usedwild-type GroEL and its ATPase-defficient mutant D398A, and studied thebinding constants between GroEL and the molten globule foldingintermediate at various concentrations of ADP and ATP. The results arecompared with titration of GroEL with the nucleotides, ADP, ATP-analogs(ATP-S and AMP-PNP) and ATP, which have shown that bothADP and the ATP analogs are bound to GroEL in a non-cooperativemanner but that ATP shows a cooperative effect. Similarly, the bindingconstant between GroEL and the folding intermediate decreased in acooperative manner with an increase in ATP concentration although itshowed non-cooperative decrease with respect to ADP concentration. Itis shown that the allosteric control of GroEL by the nucleotides isresponsible for the above behavior of GroEL and that the observeddifference between the ATP- and ADP-induced transitions of GroEL isbrought about by a small difference in an allosteric parameter (the ratio ofthe nucleotide affinities of GroEL in the high-affinity and the low-affinitystates), i.e., 4.1 for ATP and 2.6 for ADP. 相似文献
43.
Sesquiterpenoids from Ferula kuhistanica 总被引:1,自引:0,他引:1
Chen B Teranishi R Kawazoe K Takaishi Y Honda G Itoh M Takeda Y Kodzhimatov OK 《Phytochemistry》2000,54(7):717-722
Methanol extracts of the air-dried roots and stems of Ferula kuhistanica afforded seven daucane-type sesquiterpenes, called kuhistanicaol A-G, together with 13 known daucane esters. Their structures were established on the basis of spectroscopic evidence and the results of chemical reactions. 相似文献
44.
There are synaptic vesicles that are labeled by Timm's sulfide-silver staining method in the brain, suggesting that synaptic vesicles contain metals such as zinc and copper. Zinc is co-released with glutamate and the importance of zinc signaling in the intracellular compartment, in addition to extracellular compartment, is becoming recognized. Zinc can pass through calcium channels, while blocking them. Calcium signaling plays a critical role for synaptic activity and crosstalk between zinc signaling with calcium signaling through calcium channels may participate in synaptic neurotransmission including synaptic plasticity such as long-term potentiation. Copper released into the synaptic cleft during synaptic excitation may also participate in synaptic neurotransmission. Other metals including copper potentially serve as calcium channel blockers and also influence calcium signaling and zinc signaling via the interaction with metal-binding proteins such as metallothioneins. Homeostasis of metals needs to be controlled spatiotemporally for proper brain function, and their dyshomeostasis is associated with neurological diseases. However, the data on the dynamic action of metals at synapses is limited and their significance poorly understood. This paper summarizes the action of metals in synaptic neurotransmission focused on calcium signaling at glutamatergic synapses. 相似文献
45.
46.
Umezawa M Sakata C Tanaka N Kudo S Tabata M Takeda K Ihara T Sugamata M 《Cytokine》2008,43(2):105-109
The pathogenesis of endometriosis, a gynecologic disorder associated with infertility, appears to involve immune responses. However, the details involved have not been clarified. In this study, we analyzed expression levels of interleukin (IL)-6, IL-10, monocyte chemoattractant protein-1, eosinophil chemotactic protein, macrophage inflammatory protein-1α, and regulated on activation normal T cell expressed and secreted (RANTES) and CC chemokine receptor 1 in endometriotic lesions in a rat model in which endometrium is autotransplanted onto peritoneal tissue and found that they were remarkably increased, while those of IL-2, IL-4, and interferon-γ were not. These results were obtained in a rat model induced by autologous, not allogeneic, transplantation of endometrial epithelium to the peritoneum. Expression of these factors is consistent with that of endometriosis in humans. Therefore, this model may be useful in the investigation of the pathogenesis and treatment of endometriosis. 相似文献
47.
M Yoshiyama H Sakai M Teragaki K Takeuchi T Takeda M Ikata M Ishikawa I Miura 《Biochemical and biophysical research communications》1988,151(3):1408-1415
Perfused guinea-pig hearts, which were analyzed by 31P-MRS, were subjected to 30 and 60 minute ischemia and reperfused using two perfusates, one containing 200 microM inosine, and the other without inosine. After 4 hour reperfusion with inosine, ATP levels increased to 95.5% of preischemic value (30 minute ischemia) and 76.2% (60 minute ischemia). However, after 4 hour reperfusion without inosine, ATP levels increased only to 72.2% (30 minute ischemia) and to 48.2% (60 minute ischemia). In 60 minute ischemic hearts reperfused with inosine, left ventricular maximal positive dp/dt (LV dp/dt) was improved significantly to 82.4% after 6 hour reperfusion in contrast to hearts reperfused without inosine (43.1%). Administration of inosine was very useful for increasing myocardial gross energy product and improving cardiac performance. 相似文献
48.
Takeda M Chang CK Ikeya T Güntert P Chang YH Hsu YL Huang TH Kainosho M 《Journal of molecular biology》2008,380(4):608-622
The C-terminal domain (CTD) of the severe acute respiratory syndrome coronavirus (SARS-CoV) nucleocapsid protein (NP) contains a potential RNA-binding region in its N-terminal portion and also serves as a dimerization domain by forming a homodimer with a molecular mass of 28 kDa. So far, the structure determination of the SARS-CoV NP CTD in solution has been impeded by the poor quality of NMR spectra, especially for aromatic resonances. We have recently developed the stereo-array isotope labeling (SAIL) method to overcome the size problem of NMR structure determination by utilizing a protein exclusively composed of stereo- and regio-specifically isotope-labeled amino acids. Here, we employed the SAIL method to determine the high-quality solution structure of the SARS-CoV NP CTD by NMR. The SAIL protein yielded less crowded and better resolved spectra than uniform 13C and 15N labeling, and enabled the homodimeric solution structure of this protein to be determined. The NMR structure is almost identical with the previously solved crystal structure, except for a disordered putative RNA-binding domain at the N-terminus. Studies of the chemical shift perturbations caused by the binding of single-stranded DNA and mutational analyses have identified the disordered region at the N-termini as the prime site for nucleic acid binding. In addition, residues in the β-sheet region also showed significant perturbations. Mapping of the locations of these residues onto the helical model observed in the crystal revealed that these two regions are parts of the interior lining of the positively charged helical groove, supporting the hypothesis that the helical oligomer may form in solution. 相似文献
49.
Purification and properties of a lytic enzyme from the cell wall of Chlorella ellipsoidea C-87 总被引:1,自引:0,他引:1
Cell wall lytic activity was detected in the culture medium and cell wall of 1AM Chlorella ellipsoidea C-87. The enzymes of both fractions had their highest activity at pH 5. The lytic activity bound to the cell wall consisted of a polysaccharide releasing enzyme, an exo-type enzyme releasing disaccharide, and glucosidase; but only the polysaccharide releasing enzyme was solubilized by lithium chloride. A polysaccharide releasing enzyme with a molecular weight around 40 kDa was isolated from the culture medium. Hemicellulose is degraded by the polysaccharide releasing enzyme, and the rigid wall by the exo-type enzyme. 相似文献
50.
Youki Ueda Midori Takeda Kyoko Mori Hiromichi Dansako Takaji Wakita Hye-Sook Kim Akira Sato Yusuke Wataya Masanori Ikeda Nobuyuki Kato 《PloS one》2013,8(8)