全文获取类型
收费全文 | 731篇 |
免费 | 34篇 |
国内免费 | 1篇 |
专业分类
766篇 |
出版年
2023年 | 4篇 |
2022年 | 5篇 |
2021年 | 12篇 |
2020年 | 4篇 |
2019年 | 6篇 |
2018年 | 14篇 |
2017年 | 8篇 |
2016年 | 13篇 |
2015年 | 20篇 |
2014年 | 20篇 |
2013年 | 36篇 |
2012年 | 50篇 |
2011年 | 46篇 |
2010年 | 27篇 |
2009年 | 27篇 |
2008年 | 32篇 |
2007年 | 40篇 |
2006年 | 29篇 |
2005年 | 44篇 |
2004年 | 52篇 |
2003年 | 46篇 |
2002年 | 36篇 |
2001年 | 19篇 |
2000年 | 15篇 |
1999年 | 13篇 |
1998年 | 7篇 |
1997年 | 9篇 |
1996年 | 6篇 |
1995年 | 6篇 |
1994年 | 3篇 |
1993年 | 4篇 |
1992年 | 15篇 |
1991年 | 10篇 |
1990年 | 16篇 |
1989年 | 4篇 |
1988年 | 8篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1985年 | 5篇 |
1984年 | 7篇 |
1983年 | 5篇 |
1982年 | 3篇 |
1981年 | 7篇 |
1980年 | 2篇 |
1979年 | 8篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1975年 | 2篇 |
1970年 | 3篇 |
1969年 | 3篇 |
排序方式: 共有766条查询结果,搜索用时 0 毫秒
1.
Donald Wong Masao Maekawa Hidekazu Tanaka 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1992,170(4):393-402
1. Echo delay is the primary cue used by echolocating bats to determine target range. During target-directed flight, the repetition rate of pulse emission increases systematically as range decreases. Thus, we examined the delay tuning of 120 neurons in the auditory cortex of the bat, Myotis lucifugus, as repetition rate was varied. 2. Delay sensitivity was exhibited in 77% of the neurons over different ranges of pulse repetition rates (PRRs). Delay tuning typically narrowed and eventually disappeared at higher PRRs. 3. Two major types of delay-sensitive neurons were found: i) delay-tuned neurons (59%) had a single fixed best delay, while ii) tracking neurons (22%) changed their best delay with PRR. 4. PRRs from 1-100/s were represented by the population of delay-sensitive neurons, with the majority of neurons delay-sensitive at PRRs of at least 10-20/s. Thus, delay-dependent neurons in Myotis are most active during the search phase of echolocation. 5. Delay-sensitive neurons that also responded to single sounds were common. At PRRs where delay sensitivity was found, the responses to single sounds were reduced and the responses to pulse-echo pairs at particular delays were greater than the single-sound responses. In facilitated neurons (53%), the maximal delay-dependent response was always larger than the best single-sound responses, whereas in enhanced neurons (47%), these responses were comparable. The presence of neurons that respond maximally to single sounds at one PRR and to pulse-echo pairs with particular echo delays at other PRRs suggests that these neurons perform echo-ranging in conjunction with other biosonar functions during target pursuit. 相似文献
2.
M Suzuki Y Kawaguchi M Momose T Morita K Yokoyama T Miyahara 《Biochemical and biophysical research communications》1988,150(3):1193-1198
We examined the effects of several forms of vitamin D added to renal brush-border membrane suspensions on phosphate and glucose transport and on membrane fluidity. The 1,25-D stimulated and the other vitamin D decreased phosphate uptake. In contrast, glucose uptake was not affected by the treatment of vitamin D. The 1,25-D resulted in a significant shift of the lower transition temperature in Arrhenius plots for phosphate, but not for glucose uptakes, from 15 degrees C to 11.5 degrees C. These data indicate that the 1,25-D may alter membrane fluidity, limited to the phosphate transporter, thus affecting the phosphate uptake. 相似文献
3.
S. Kawano S. Nishibayashi N. Shiraishi M. Miyahara T. Kuroiwa 《Experimental cell research》1983,149(2)
In Physarum polycephalum, microplasmodia differentiated into spherules when cultures were aged for 8–10 days. Respiration rates of the microplasmodia decreased rapidly with ageing to a 90% decrease in oxygen consumption over 9 days. We studied this phenomena by isolating and characterizing mitochondria from microplasmodia and spherules at different stages of spherulation. Oxygen uptake by the isolated mitochondria decreased with spherulation. Morphological and biochemical analyses showed that mitochondrial differentiation to inactive state was characterized by a decrease not only in dimension but also of content (DNA, RNA and protein). Diminutive mitochondria contained small particle-shaped mitochondrial nuclei. The DNA content, measured by microscopic fluorometry, was about 1.15 and 0.58 × 10−10 g, which corresponded to about 16 and 8 genome copies, respectively (e.g., 32 genome copies per mitochondrion at mitochondrial G1). Restriction endonuclease analysis showed that the physical structure and methylation pattern of the mtDNA had not changed although the DNA content per mitochondrion had decreased remarkably with spherulation. This showed that changes in the ploidy level of the mitochondrial nucleus during spherulation were due to reduction in the number of whole mitochondrial genomes. 相似文献
4.
Y Mitsuuchi T Kawamoto Y Naiki K Miyahara K Toda I Kuribayashi T Orii K Yasuda K Miura K Nakao 《Biochemical and biophysical research communications》1992,182(2):974-979
The gene for steroid 18-hydroxylase (P-450C18) has been recently assigned to encode corticosterone methyl oxidases Type I and Type II which were previously postulated to catalyze the final two steps in the biosynthesis of aldosterone in humans. Molecular genetic analysis of the P-450C18 gene is three patients from three different families affected with CMO II deficiency has indicated that a point mutation of CGG----TGG (181Arg----Trp) in exon 3 and one of GTG----GCG (386Val----Ala) in exon 7 occur exclusively in the gene of the patients. Analysis of PCR products by restriction enzymes (HapII and HphI) has indicated that the patients are homozygous and the unaffected parent is heterozygous for both mutations, in accordance with the established concept that CMO II deficiency is inherited in an autosomal recessive manner. These data clearly provide the molecular genetic basis for the characteristic biochemical phenotype of CMO II clinical variants. 相似文献
5.
Hidekazu Sawada Takashi Suzuki Shun-ichi Akiyama Yoshio Nakao 《Applied microbiology and biotechnology》1990,32(5):556-559
Summary Gel-filtration analysis of a mixture of cyclodextrin (CyD) and lankacidin C showed that -CyD had strong, -CyD weak and -CyD no affinity for lankacidin C. Lankacidin C production activity, which was assayed by measuring the incorporation of l-[methyl-14C-]methionine into the lankacidin molecule, was the greatest with cells grown in the presence of -CyD, less with -CyD and the least with -CyD. Lankamycin and T-2636M, which are by-products in lankacidin C fermentation, were not included by -CyD and their production was not stimulated by -CyD. It was apparent that the stimulatory effect of CyD was closely related to the formation of an inclusion complex between CyD and the antibiotic. Lankacidin C biosynthesis was repressed by preincubating cells with lankacidin C, while the repressive effect of lankacidin C was abrogated by the inclusion by -CyD. Thus, abrogation of feed-back repression seems to be a main mechanism of the effect of CyD. However, -CyD, which had no affinity for lankacidin C, stimulated the production to the least extent and exhibited a complementary effect on the stimulation by -CyD or -CyD. -CyD also caused a change in cell morphology and cell-surface hydrophobicity. It was assumed that the modification of the cell surface is a secondary mechanism of the effect of CyD.The second report of the stimulatory effect of cyclodextrins on lankacidin fermentationOffprint requests to: H. Sawada 相似文献
6.
Kazuki Sugawara Hidekazu Suzuki Mitsunobu Kamiya Keigo Osada Andrzej Witkowski 《Phycological Research》2023,71(4):182-192
The canal-bearing diatom genus Nagumoea, described based on only morphological evidence, was tentatively assigned to the order Bacillariales, although its phylogenetic position remained unclear. Because three isolates of Nagumoea (SK002, SK024 and SK053) were successfully established from Japanese coasts, we performed their morphological observations and molecular phylogenetic analyses to discuss the phylogeny and taxonomic position of this genus. Strains SK002 and SK024 were identified as Nagumoea africana, whereas SK053 conformed with Nagumoea serrata. There was high interspecific divergence between N. africana and N. serrata in the rbcL sequences (8.03–8.17%), indicating their distinctness. Furthermore, intraspecific variations were detected within N. africana (2.35%) in the rbcL, implying its cryptic diversity. The maximum likelihood and Bayesian phylogenetic trees inferred from the plastid rbcL, psbC and nuclear 18S rDNA genes recovered Nagumoea as monophyletic with strong statistical support and embedded within an unresolved, poorly supported lineage containing Achnanthes, Craspedostauros, Staurotropis and Undatella in the canal-bearing order Bacillariales (= the family Bacillariaceae). Although the constrained tree based on the monophyly of Nagumoea and the other canal-bearing clade (Surirellales and Rhopalodiales) was statistically rejected by the topology tests, the phylogenetic position of Nagumoea with other Bacillarialean members remains equivocal. The possession of two plastids positioned fore and aft, observed in the present study, and lack of keel, typical of the Bacillariales, indicate the possibility of Nagumoea being part of the ingroup of the Bacillariales or its closely related outgroup. 相似文献
7.
Marwa Said El-Desoky Rino Takeuchi Hidekazu Katayama Naoaki Tsutsui 《Journal of peptide science》2023,29(12):e3529
The insulin superfamily comprises a group of peptides with diverse physiological functions and is conserved across the animal kingdom. Insulin-like peptides (ILPs) of crustaceans are classified into four major types: insulin, relaxin, gonadulin, and androgenic gland hormone (AGH)/insulin-like androgenic gland factor (IAG). Of these, the physiological functions of AGH/IAG have been clarified to be the regulation of male sex differentiation, but those of the other types have not been uncovered. In this study, we chemically synthesized Maj-ILP1, an ILP identified in the ovary of the kuruma prawn Marsupenaeus japonicus, using a combination of solid-phase peptide synthesis and regioselective disulfide bond formation reactions. As the circular dichroism spectral pattern of synthetic Maj-ILP1 is typical of other ILPs reported thus far, the synthetic peptide likely possessed the proper conformation. Functional analysis using ex vivo tissue incubation revealed that Maj-ILP1 significantly increased the expression of the yolk protein genes Maj-Vg1 and Maj-Vg2 in the hepatopancreas and Maj-Vg1 in the ovary of adolescent prawns. This is the first report on the synthesis of a crustacean ILP other than IAGs and also shows the positive relationship between the reproductive process and female-dominant ILP. 相似文献
8.
Hidekazu Nishimura Kanetsu Sugawara Peng Gao Yasushi Muraki Seiji Hongo Fumio Kitame Kiyoto Nakamura 《Microbiology and immunology》1995,39(9):737-740
The HMV-II cells infected with influenza C virus were labeled with inorganic [32P]phosphate to identify phosphorylated proteins. Analysis by radioimmunoprecipitation with antiviral serum or monoclonal antibodies revealed that three major structural proteins of the virus, hemagglutinin-esterase (HE), nucleoprotein (NP), and matrix protein (M1) are all phosphorylated in both infected cells and virions. It was also observed that, in the presence of trypsin (10 μg/ml), the unphosphorylated form of the HE glycoprotein was cleaved efficiently whereas the phosphorylated form was not, raising the possibility that phosphorylation of HE may influence its susceptibility to degradation by proteolytic enzymes. 相似文献
9.
Formation of collagen fibrils in vitro by cleavage of procollagen with procollagen proteinases 总被引:14,自引:0,他引:14
A new system was developed for studying the assembly of collagen fibrils in vitro. A partially purified enzyme preparation containing both procollagen N-proteinase and c-proteinase (EC 3.4.24.00) activities was used to initiate fibril formation by removal of the N- and C-propeptides from type I procollagen in a physiological buffer at 35-37 degrees C. The kinetics of fibril formation were similar to those observed for fibril formation with tissue-extracted collagen in the same buffer system, except that the lag phase was longer. The longer lag phase was in part accounted for by the time required to convert procollagen to collagen. Similar results were obtained when an intermediate containing the C-propeptide but not the N-propeptide was used as a substrate. Therefore, removal of the c-propeptide appeared to be the critical step for fibril formation under the conditions used here. The fibrils formed by enzymic cleavage of procollagen or pCcollagen appeared microscopically to be more tightly packed than fibrils formed directly from collagen under the same conditions. This impression was confirmed by the observation that the fibrils formed by cleavage of procollagen were stable to temperatures 1.5-2 degrees C higher than fibers formed from extracted collagen under the same conditions. When smaller amounts of procollagen proteinase were used, the rate of cleavage of procollagen to collagen was markedly reduced. The fibrils which formed under these conditions were up to 3 micrometers in diameter. Some appeared to contain branch points. 相似文献
10.
Minoru Ishii Shunpei Uemoto Kunimitsu Fujieda Mizuo Nonaka Yukihiro Shoyama Yumi Miyahara Itsuo Nishioka 《Phytochemistry》1979,18(7):1211-1213
A new phenolic, hydroxyeucomic acid, and dopamine were isolated from Cattleya trianaei and their biological activities examined. 相似文献