全文获取类型
收费全文 | 1261篇 |
免费 | 83篇 |
专业分类
1344篇 |
出版年
2023年 | 2篇 |
2022年 | 8篇 |
2021年 | 14篇 |
2020年 | 6篇 |
2019年 | 10篇 |
2018年 | 19篇 |
2017年 | 17篇 |
2016年 | 26篇 |
2015年 | 34篇 |
2014年 | 50篇 |
2013年 | 92篇 |
2012年 | 69篇 |
2011年 | 85篇 |
2010年 | 49篇 |
2009年 | 54篇 |
2008年 | 86篇 |
2007年 | 101篇 |
2006年 | 76篇 |
2005年 | 75篇 |
2004年 | 90篇 |
2003年 | 78篇 |
2002年 | 88篇 |
2001年 | 6篇 |
2000年 | 14篇 |
1999年 | 22篇 |
1998年 | 22篇 |
1997年 | 16篇 |
1996年 | 6篇 |
1995年 | 12篇 |
1994年 | 8篇 |
1993年 | 12篇 |
1992年 | 10篇 |
1991年 | 14篇 |
1990年 | 8篇 |
1989年 | 10篇 |
1988年 | 5篇 |
1987年 | 5篇 |
1986年 | 3篇 |
1985年 | 5篇 |
1984年 | 4篇 |
1983年 | 4篇 |
1982年 | 9篇 |
1981年 | 5篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1974年 | 2篇 |
1963年 | 1篇 |
1962年 | 1篇 |
1961年 | 1篇 |
排序方式: 共有1344条查询结果,搜索用时 15 毫秒
31.
The monogenean Pseudodactylogyrus kamegaii sp. n. is described, based on specimens collected from the gills of wild Japanese eel Anguilla japonica caught in Chiba Prefecture, Japan. This species is the most similar to P. anguillae (Yin and Sproston, 1948), but different in the shape and measurements of the male copulatory organ, vagina and marginal hook. This new species was collected from the eel in brackish waters, while P. anguillae and P. bini, the other known pseudodactylogyrids of Japanese eel, have been recorded only in fresh waters. 相似文献
32.
Komoike Y Kawamura A Shindo N Sato C Satoh J Shiurba R Higashinakagawa T 《Biochemical and biophysical research communications》2005,328(4):858-866
We analyzed Polycomb group gene ph2alpha functionally in zebrafish embryos by a gene knock-down procedure using morpholino antisense oligos. Inhibition of ph2alpha message translation resulted in abnormal epibolic movements as well as a thick tailbud or incomplete covering of the yolk plug. At the 24hpf stage, morphants had short trunks and tails, phenotypes similar to those with disturbances in FGF signaling. Accordingly, we looked at the effects of ph2alpha expression upstream and downstream of the FGF pathway. Treatment with SU5402, an inhibitor of Fgfrs, or injection of dominant-negative Fgfr1 DNA markedly reduced ph2alpha expression in the tailbud. In addition, cells expressing mRNAs for no tail, spadetail, myoD, and papc, which are involved in FGF-related development of posterior mesoderm, were distributed abnormally. Collectively, the data argue that ph2alpha is required for epiboly and tailbud formation, acting downstream of the FGF signaling pathway. 相似文献
33.
Effects of Cl2MDP-encapsulating liposomes in a murine model of Pseudomonas aeruginosa-induced sepsis
Pseudomonas aeruginosa is a pathogen that frequently causes acute lung injury, bacteremia and sepsis in critically ill patients. As tissue macrophages are a major producer of inflammatory mediators that contribute to septic physiology, and are essential for eliminating bacteria from the circulation, we investigated the role of tissue macrophages in the generation of both inflammatory and anti-inflammatory cytokines in septic shock by using our mouse model of P. aeruginosa pneumonia. To see the effects of tissue macrophage depletion, we intravenously injected dichloromethylene-diphosphonate (Cl2MDP)-encapsulating liposomes in mice. Two days after the liposome injection, we instilled cytotoxic P. aeruginosa (PA103) into the lung that disseminates and causes septic shock. After the infection, we collected blood and bronchoalveolar lavage fluids. The samples were then analyzed for TNF-alpha, MIP-2, and IL-10 concentration. We compared these results to control mice that received either liposomes without Cl2MDP or phosphate buffered saline alone. Plasma TNF-alpha, MIP-2, and IL-10 levels were significantly decreased in the tissue macrophage-depleted mice compared to the control groups of mice. Although depletion of tissue macrophages by Cl2MDP-liposome administration did not affect the severity of bacteremia or the survival of infected mice, these results imply that tissue macrophages have a major role in the production of both proinflammatory and anti-inflammatory cytokines in the circulation and in the causing septic physiology associated with P. aeruginosa pneumonia. 相似文献
34.
The discovery of separate 5' and 3' halves of transfer RNA (tRNA) molecules-so-called split tRNA-in the archaeal parasite Nanoarchaeum equitans made us wonder whether ancestral tRNA was encoded on 1 or 2 genes. We performed a comprehensive phylogenetic analysis of tRNAs in 45 archaeal species to explore the relationship between the three types of tRNAs (nonintronic, intronic and split). We classified 1953 mature tRNA sequences into 22 clusters. All split tRNAs have shown phylogenetic relationships with other tRNAs possessing the same anticodon. We also mimicked split tRNA by artificially separating the tRNA sequences of 7 primitive archaeal species at the anticodon and analyzed the sequence similarity and diversity of the 5' and 3' tRNA halves. Network analysis revealed specific characteristics of and topological differences between the 5' and 3' tRNA halves: the 5' half sequences were categorized into 6 distinct groups with a sequence similarity of >80%, while the 3' half sequences were categorized into 9 groups with a higher sequence similarity of >88%, suggesting different evolutionary backgrounds of the 2 halves. Furthermore, the combinations of 5' and 3' halves corresponded with the variation of amino acids in the codon table. We found not only universally conserved combinations of 5'-3' tRNA halves in tRNA(iMet), tRNA(Thr), tRNA(Ile), tRNA(Gly), tRNA(Gln), tRNA(Glu), tRNA(Asp), tRNA(Lys), tRNA(Arg) and tRNA(Leu) but also phylum-specific combinations in tRNA(Pro), tRNA(Ala), and tRNA(Trp). Our results support the idea that tRNA emerged through the combination of separate genes and explain the sequence diversity that arose during archaeal tRNA evolution. 相似文献
35.
Wada K Maeda YY Watanabe K Oshio T Ueda T Takahashi G Yokohama M Saito J Seki Y Takahama S Ishii R Shitara H Taya C Yonekawa H Kikkawa Y 《Mammalian genome》2011,22(11-12):693-702
The Rinshoken cataract (rct) mutation, which causes congenital cataracts, is a recessive mutation found in SJL/J mice. All mutants present with opacity in the lens by 2?months of age. The rct locus was mapped to a 1.6-Mb region in Chr 4 that contains the Foxe3 gene. This gene is responsible for cataracts in humans and mice, and it plays a crucial role in the development of the lens. Furthermore, mutation of Foxe3 causes various ocular defects. We sequenced the genomic region of Foxe3, including the coding exons and UTRs; however, no mutations were discovered in these regions. Because there were no differences in Foxe3 sequences between the rct/rct and wild-type mice, we inferred that a mutation was located in the regulatory regions of the Foxe3 gene. To test this possibility, we sequenced a 5' noncoding region that is highly conserved among vertebrates and is predicted to be the major enhancer of Foxe3. This analysis revealed a deletion of 22-bp located approximately 3.2-kb upstream of the start codon of Foxe3 in rct mice. Moreover, we demonstrated by RT-PCR and in situ hybridization that the rct mutant has reduced expression of Foxe3 in the lens during development. We therefore suggest that cataracts in rct mice are caused by reduced Foxe3 expression in the lens and that this decreased expression is a result of a deletion in a cis-acting regulatory element. 相似文献
36.
So Kato Yasushi Oshima Hiroyuki Oka Hirotaka Chikuda Yujiro Takeshita Kota Miyoshi Naohiro Kawamura Kazuhiro Masuda Junichi Kunogi Rentaro Okazaki Seiichi Azuma Nobuhiro Hara Sakae Tanaka Katsushi Takeshita 《PloS one》2015,10(4)
Objectives
The Japanese Orthopaedic Association (JOA) score is widely used to assess the severity of clinical symptoms in patients with cervical compressive myelopathy, particularly in East Asian countries. In contrast, modified versions of the JOA score are currently accepted as the standard tool for assessment in Western countries. The objective of the present study is to compare these scales and clarify their differences and interchangeability and verify their validity by comparing them to other outcome measures.Materials and Methods
Five institutions participated in this prospective multicenter observational study. The JOA and modified JOA (mJOA) proposed by Benzel were recorded preoperatively and at three months postoperatively in patients with cervical compressive myelopathy who underwent decompression surgery. Patient reported outcome (PRO) measures, including Japanese Orthopaedic Association Cervical Myelopathy Evaluation Questionnaire (JOACMEQ), the Short Form-12 (SF-12) and the Neck Disability Index (NDI), were also recorded. The preoperative JOA score and mJOA score were compared to each other and the PRO values. A Bland-Altman analysis was performed to investigate their limits of agreement.Results
A total of ninety-two patients were included. The correlation coefficient (Spearman’s rho) between the JOA and mJOA was 0.87. In contrast, the correlations between JOA/mJOA and the other PRO values were moderate (|rho| = 0.03 – 0.51). The correlation coefficient of the recovery rate between the JOA and mJOA was 0.75. The Bland-Altman analyses showed that limits of agreement were 3.6 to -1.2 for the total score, and 55.1% to -68.8% for the recovery rates.Conclusions
In the present study, the JOA score and the mJOA score showed good correlation with each other in terms of their total scores and recovery rates. Previous studies using the JOA can be interpreted based on the mJOA; however it is not ideal to use them interchangeably. The validity of both scores was demonstrated by comparing these values to the PRO values. 相似文献37.
Tokuo Ogawa Junichi Sugenoya Norikazu Ohnishi Keiko Natsume Megumi Ochiai Motohiko Nishida Norihiko Shinoda Kenichi Katoh Ritsuko Imamura 《International journal of biometeorology》1991,35(1):18-23
In an attempt to detect differences in the thermal effect of infrared irradiation of different wavelengths, transient sweating response to infrared irradiation in various spectral regions was examined. In Series 1, the ventral or dorsal surface of the nude subject was irradiated repetitively for a period of 4 min (2 min on, 2 min off) by each of three kinds of infrared heaters with main emissivity in near-infrared (NIR; 0.7–2.8 m), intermediate-infrared (MIR; 1.5–5.8 m), and far-infrared (FIR; 2.8–25 m) regions. The sweating response on a non-irradiated area tended to be the greatest with MIR, while the magnitude of the sweating response on the irradiated area showed no consistent differences among various wavelengths. The results infer that MIR stimulated cutaneous thomoreceptors most effectively, while its direct effect on local sweat gland activity was minimal. In Series 2, the effects of 9–12 min irradiations in more restricted ranges of wavelength were compared by the combination of the three kinds of heaters with filters (translucent to wavelength ranges of 1.3–2.7, 2.7–3.5, 3.6–8.0 m, respectively). The sweating response on a remote area was predominantly greater with the range of 2.7–3.5 m than with the other wavelength ranges, while the local effect on sweating was minimal with this range. The results of Series 2 reinforce those of Series 1, indicating that the degree of stimulation of cutaneous thermoreceptors and of direct thermal effect on sweat gland activity differ with spectral regions incident on the skin, thus affecting local and remote effects on the sweating response. 相似文献
38.
Identification of Tau and MAP2 as novel substrates of Rho-kinase and myosin phosphatase 总被引:2,自引:0,他引:2
Amano M Kaneko T Maeda A Nakayama M Ito M Yamauchi T Goto H Fukata Y Oshiro N Shinohara A Iwamatsu A Kaibuchi K 《Journal of neurochemistry》2003,87(3):780-790
Rho-kinase and myosin phosphatase are implicated in the phosphorylation-state of myosin light chain downstream of Rho, which is thought to induce smooth muscle contraction and stress fibre formation in non-muscle cells. Here, we found that microtubule-associated proteins, Tau and MAP2, interacted with the myosin-binding subunit (MBS) of myosin phosphatase, and were the possible substrates of both Rho-kinase and myosin phosphatase. We determined the phosphorylation sites of Tau (Thr245, Thr377, Ser409) and MAP2 (Ser1796) by Rho-kinase. We also found that Rho-kinase phosphorylated Tau at Ser262 to some extent. Phosphorylation by Rho-kinase decreased the activity of Tau to promote microtubule assembly in vitro. Substitutions of Ala for Ser/Thr at the phosphorylation sites of Tau (Tau-AAA) did not affect the activity to promote microtubule assembly, while substitutions of Asp for Ser/Thr (Tau-DDD), which are expected to mimic the phosphorylation-state of Tau, slightly reduced the activity. When Tau, or mutated forms of Tau, were expressed in PC12 cells, followed by treatment with cytochalasin D, they promoted extension of the cell process in a cytochalasin-dependent manner. However, Tau-DDD showed the weaker activity in this capacity than wild-type Tau or Tau-AAA. These results suggest that the phosphorylation-state of these residues of Tau affects its activity both in vitro and in vivo. Thus, it is likely that the Rho-kinase/MBS pathway regulates not only the actin-myosin system but also microtubule dynamics. 相似文献
39.
Structures of the alpha L I domain and its complex with ICAM-1 reveal a shape-shifting pathway for integrin regulation 总被引:7,自引:0,他引:7
Shimaoka M Xiao T Liu JH Yang Y Dong Y Jun CD McCormack A Zhang R Joachimiak A Takagi J Wang JH Springer TA 《Cell》2003,112(1):99-111
The structure of the I domain of integrin alpha L beta 2 bound to the Ig superfamily ligand ICAM-1 reveals the open ligand binding conformation and the first example of an integrin-IgSF interface. The I domain Mg2+ directly coordinates Glu-34 of ICAM-1, and a dramatic swing of I domain residue Glu-241 enables a critical salt bridge. Liganded and unliganded structures for both high- and intermediate-affinity mutant I domains reveal that ligand binding can induce conformational change in the alpha L I domain and that allosteric signals can convert the closed conformation to intermediate or open conformations without ligand binding. Pulling down on the C-terminal alpha 7 helix with introduced disulfide bonds ratchets the beta 6-alpha 7 loop into three different positions in the closed, intermediate, and open conformations, with a progressive increase in affinity. 相似文献
40.
Light regulation of photosystem I (PSI) biogenesis was studied in a unicellular green alga, Chlamydomonas reinhardtii. When Chlamydomonas cells were transferred from darkness to the light, mRNAs for both nuclear- and chloroplast-encoded PSI subunits were induced in concert. This light induction was inhibited by photosynthetic electron transport (PET) inhibitors, 3-(3,4 dichlorophenyl)-1,1-dimethylurea and 2,5-dibromo-3-methyl-6 isopropyl-p-benzoquinone, but not by an uncoupler, carbonyl cyanide m-chlorophenylhydrazone. This indicated that PET plays a pivotal role in the light induction of PSI subunit mRNAs, but that photophosphorylation is not necessary. When we irradiated the Chlamydomonas cells with PSI-light (695 nm) or PSII-light (644 nm), which makes the plastoquinone pool oxidative and reductive, respectively, PSII-light caused the accumulation of PSI proteins more abundantly than did PSI-light. However, there was no difference for the PSI subunit mRNA levels between these light sources. From these results, we conclude that PET plays dual roles in the regulation of PSI biogenesis in Chlamydomonas: when cells are illuminated, PET first induces the PSI subunit mRNAs irrespective of the redox state of the intersystem electron carriers, and then their redox state fine-tunes PSI biogenesis at translational and/or post-translational steps to fulfil the chromatic adaptation. 相似文献