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961.
Ant fauna on Mallotus japonicus, a shrub with extrafloral nectaries, was investigated in two types of habitat (the villages and the forest‐edges) on subtropical Okinawa Island, Japan. Twenty and 16 ant species were found, including 11 and 6 tramp species in the villages and in the forest‐edges, respectively. Occurrence of tramp species was higher in the villages than in the forest edges, supporting the idea that tramp species tend to dominate in disturbed habitats. Nevertheless, the richness of native ants was almost the same across the two habitat types. Consequently, the ant species diversity on M. japonicus appeared higher in the villages. However, monitoring has to be continued to determine whether the above findings represent a stable phenomenon of the community or just a temporary state. 相似文献
962.
Hiroko Tokunaga Shoko Saito Kazuki Sakai Rui Yamaguchi Iwao Katsuyama Tomohiro Arakawa Kikuo Onozaki Tsutomu Arakawa Masao Tokunaga 《Applied microbiology and biotechnology》2010,86(2):649-658
The amino acid composition of halophilic enzymes is characterized by an abundant content of acidic amino acid, which confers
to the halophilic enzymes extensive negative charges at neutral pH and high aqueous solubility. This negative charge prevents
protein aggregation when denatured and thereby leads to highly efficient protein refolding. β-Lactamase from periplasmic space
of moderate halophile (BLA), a typical halophilic enzyme, can be readily expressed as a native, active form in Escherichia coli cytoplasm. Similar to other halophilic enzymes, BLA is soluble upon denaturation by heat or urea treatments and, hence, can
be efficiently refolded. Such high solubility and refolding efficiency make BLA a potential fusion partner for expression
of aggregation-prone heterologous proteins to be expressed in E. coli. Here, we succeeded in the soluble expression of several “difficult-to-express” proteins as a BLA fusion protein and verified
biological activities of human interleukin 1α and human neutrophil α-defensin, HNP-1. 相似文献
963.
964.
Kazuki Takeda Kouji Kusumoto Yu Hirano Kunio Miki 《Journal of structural biology》2010,169(2):135-144
The positions of hydrogen atoms significantly define protein functions. However, such information from protein crystals is easily disturbed by X-rays. The damage can not be prevented completely even in the data collection at cryogenic temperatures. Therefore, the influence of X-rays should be precisely estimated in order to derive meaningful information from the crystallographic results. Diffraction data from a single crystal of the high-potential iron-sulfur protein (HiPIP) from Thermochromatium tepidum were collected at an undulator beamline of a third generation synchrotron facility, and were merged into three data sets according to X-ray dose. A series of structures analyzed at 0.70 Å shows detailed views of the X-ray induced perturbation, such as the positional changes of hydrogen atoms of a water molecule. Based on the results, we successfully collected a low perturbation data set using attenuated X-rays. There was no influence on the crystallographic statistics, such as the relative B factors, during the course of data collection. The electron densities for hydrogen atoms were more clear despite the slightly lower resolution. 相似文献
965.
Misako Taichi Tohimasa Yamazaki Kazuki Kawahara Daisuke Motooka Shota Nakamura Shusaku Harada Tadashi Teshima Tadayasu Ohkubo Yuji Kobayashi Yuji Nishiuchi 《Journal of peptide science》2010,16(7):329-336
A 12‐residue MST isolated from a marine organism is a potent serine protease inhibitor that has a double cyclic structure composed of two ester linkages formed between the β‐hydroxyl and β‐carboxyl groups, Thr3‐Asp9 and Ser8‐Asp11. MST was synthesized by a regioselective esterification procedure employing two sets of orthogonally removable side‐chain protecting groups for the Asp and Ser/Thr residues. In the MST molecule, there were no significant changes observed in yield by changing the order of esterification. SAR study of MST revealed that the minimum required structure for expressing the inhibitory activity is the sequence (1–9) in a monocyclic structure where Pro7 located in the ring plays a crucial role in keeping the structural rigidity. By applying the structural motif of MST, we rationally designed protease inhibitory specificities that differ from those of the natural product. Copyright © 2010 European Peptide Society and John Wiley & Sons, Ltd. 相似文献
966.
967.
Kanazawa K Uehara M Yanagitani H Hashimoto T 《Archives of biochemistry and biophysics》2006,455(2):197-203
Antioxidative flavonoids, ubiquitously included in vegetables, fruits and teas, are expected to prevent degenerative diseases. It is unclear, however, whether flavonoids can enter the cellular nuclei and suppress the oxidative damage of DNA. Here, several flavonoids at the physiological concentration of 10 microM were dosed to 2.5x10(7) HepG2 cells. The nuclei were isolated and determined in the incorporated flavonoid levels, and simultaneously exposed to reactive oxygen generated from 25 mM of 2,2'-azobis(2-amidinopropane) dihydrochloride. Most of the tested flavonoids were incorporated into the cells in the range between 1000 and 1600 pmol/10(7) cells, and were in the nuclei at 250-450 pmol/10(7) cells at the maximum incorporation after 30min of cell incubation. In the cells, 23% of quercetin (3,5,7,3',4'-OH) and 8% of luteolin (5,7,3',4'-OH) were the original aglycone forms and the others were the methylated and gulucuronide/sulfate conjugates, while 72% of kaempferol (3,5,7,4'-OH) and 85% of apigenin (5,7,4'-OH) were aglycones and located in the nuclei at the similar ratio of metabolites. Quercetin and luteolin significantly suppressed the formation of 8-oxo-7,8-dihydrodeoxyguanosine by 25% and 15%, respectively, compared to those in 0-time incubated cells with the flavonoids. Under such conditions of low level and hydroxyl-masked in the nuclei, the limited flavonoids were bioavailable antioxidants to prevent genetic damage and they were B-ring catechols such as quercetin and luteolin. 相似文献
968.
Priming-Boosting Vaccination with Recombinant Mycobacterium bovis Bacillus Calmette-Guérin and a Nonreplicating Vaccinia Virus Recombinant Leads to Long-Lasting and Effective Immunity
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969.
We propose an analog integrated circuit that implements a resonate-and-fire neuron (RFN) model based on the Lotka-Volterra (LV) system. The RFN model is a spiking neuron model that has second-order membrane dynamics, and thus exhibits fast damped subthreshold oscillation, resulting in the coincidence detection, frequency preference, and post-inhibitory rebound. The RFN circuit has been derived from the LV system to mimic such dynamical behavior of the RFN model. Through circuit simulations, we demonstrate that the RFN circuit can act as a coincidence detector and a band-pass filter at circuit level even in the presence of additive white noise and background random activity. These results show that our circuit is expected to be useful for very large-scale integration (VLSI) implementation of functional spiking neural networks. 相似文献
970.
Transgenic Arabidopsis plants expressing the rice dehydroascorbate reductase gene are resistant to salt stress 总被引:3,自引:0,他引:3
Ushimaru T Nakagawa T Fujioka Y Daicho K Naito M Yamauchi Y Nonaka H Amako K Yamawaki K Murata N 《Journal of plant physiology》2006,163(11):1179-1184
Vitamin C (l-ascorbate) is important for antioxidative and metabolic functions in both plants and humans. Ascorbate itself is oxidized to dehydroascorbate during the process of antioxidation, and dehydroascorbate reductase (DHAR, EC 1.8.5.1) re-reduces the oxidized ascorbate. Therefore, this enzyme is assumed to be critical for ascorbate recycling. Here we show that the expression of rice DHAR in transgenic Arabidopsis thaliana enhanced resistance to salt stress. Salt tolerance was remarkably improved despite slight increases in DHAR activity and total ascorbate. This study provides direct evidence for the importance of DHAR in salt tolerance. 相似文献