全文获取类型
收费全文 | 6220篇 |
免费 | 360篇 |
国内免费 | 2篇 |
专业分类
6582篇 |
出版年
2023年 | 14篇 |
2022年 | 36篇 |
2021年 | 95篇 |
2020年 | 64篇 |
2019年 | 65篇 |
2018年 | 112篇 |
2017年 | 81篇 |
2016年 | 153篇 |
2015年 | 207篇 |
2014年 | 267篇 |
2013年 | 444篇 |
2012年 | 425篇 |
2011年 | 418篇 |
2010年 | 275篇 |
2009年 | 283篇 |
2008年 | 464篇 |
2007年 | 421篇 |
2006年 | 419篇 |
2005年 | 425篇 |
2004年 | 444篇 |
2003年 | 393篇 |
2002年 | 335篇 |
2001年 | 50篇 |
2000年 | 40篇 |
1999年 | 50篇 |
1998年 | 75篇 |
1997年 | 62篇 |
1996年 | 39篇 |
1995年 | 53篇 |
1994年 | 46篇 |
1993年 | 36篇 |
1992年 | 36篇 |
1991年 | 15篇 |
1990年 | 19篇 |
1989年 | 22篇 |
1988年 | 14篇 |
1987年 | 18篇 |
1986年 | 15篇 |
1985年 | 14篇 |
1984年 | 15篇 |
1983年 | 13篇 |
1982年 | 21篇 |
1981年 | 21篇 |
1980年 | 12篇 |
1979年 | 12篇 |
1978年 | 6篇 |
1977年 | 11篇 |
1976年 | 6篇 |
1974年 | 5篇 |
1969年 | 4篇 |
排序方式: 共有6582条查询结果,搜索用时 15 毫秒
171.
Soluble Methane Monooxygenase Gene Clusters from Trichloroethylene-Degrading Methylomonas sp. Strains and Detection of Methanotrophs during In Situ Bioremediation 下载免费PDF全文
Toru Shigematsu Satoshi Hanada Masahiro Eguchi Yoichi Kamagata Takahiro Kanagawa Ryuichiro Kurane 《Applied microbiology》1999,65(12):5198-5206
The soluble MMO (sMMO) gene clusters from group I methanotrophs were characterized. An 8.1-kb KpnI fragment from Methylomonas sp. strain KSWIII and a 7.5-kb SalI fragment from Methylomonas sp. strain KSPIII which contained the sMMO gene clusters were cloned and sequenced. The sequences of these two fragments were almost identical. The sMMO gene clusters in the fragment consisted of six open reading frames which were 52 to 79% similar to the corresponding genes of previously described sMMO gene clusters of the group II and group X methanotrophs. The phylogenetic analysis of the predicted amino acid sequences of sMMO demonstrated that the sMMOs from these strains were closer to that from M. capsulatus Bath in the group X methanotrophs than to those from Methylosinus trichosporium OB3b and Methylocystis sp. strain M in the group II methanotrophs. Based on the sequence data of sMMO genes of our strains and other methanotrophs, we designed a new PCR primer to amplify sMMO gene fragments of all the known methanotrophs harboring the mmoX gene. The primer set was successfully used for detecting methanotrophs in the groundwater of trichloroethylene-contaminated sites during in situ-biostimulation treatments. 相似文献
172.
Daichi Kita Satoshi Shibata Yuichiro Kikuchi Eitoyo Kokubu Koji Nakayama Atsushi Saito Kazuyuki Ishihara 《Applied and environmental microbiology》2016,82(6):1756-1766
Capnocytophaga ochracea is a Gram-negative, rod-shaped bacterium that demonstrates gliding motility when cultured on solid agar surfaces. C. ochracea possesses the ability to form biofilms; however, factors involved in biofilm formation by this bacterium are unclear. A type IX secretion system (T9SS) in Flavobacterium johnsoniae was shown to be involved in the transport of proteins (e.g., several adhesins) to the cell surface. Genes orthologous to those encoding T9SS proteins in F. johnsoniae have been identified in the genome of C. ochracea; therefore, the T9SS may be involved in biofilm formation by C. ochracea. Here we constructed three ortholog-deficient C. ochracea mutants lacking sprB (which encodes a gliding motility adhesin) or gldK or sprT (which encode T9SS proteins in F. johnsoniae). Gliding motility was lost in each mutant, suggesting that, in C. ochracea, the proteins encoded by sprB, gldK, and sprT are necessary for gliding motility, and SprB is transported to the cell surface by the T9SS. For the ΔgldK, ΔsprT, and ΔsprB strains, the amounts of crystal violet-associated biofilm, relative to wild-type values, were 49%, 34%, and 65%, respectively, at 48 h. Confocal laser scanning and scanning electron microscopy revealed that the biofilms formed by wild-type C. ochracea were denser and bacterial cells were closer together than in those formed by the mutant strains. Together, these results indicate that proteins exported by the T9SS are key elements of the gliding motility and biofilm formation of C. ochracea. 相似文献
173.
Hidekazu Tanaka Takahiro Yamaguchi Kae Hachiya Kazuhiro Miwa Jun Shinoda Masahide Hayashi Shinichi Ogawa Hironori Nishibori Satoshi Goshima Masayuki Matsuo 《Reports of Practical Oncology and Radiotherapy》2018,23(3):215-219
Aim
To define the optimal margin on MRI scans in the re-radiation planning of recurrent glioblastoma using methionine positron emission tomography (MET-PET).Background
It would be very useful if the optimal margin on MRI to cover the uptake area on MET-PET is known.Materials and Methods
CT, MRI, and MET-PET were performed separately over the course of 2 weeks. Among the MRI scans, we used the contrast-enhanced T1-weighted images (Gd-MRI) and T2-weighted images (T2-MRI). The Gd-MRI-based clinical target volume (CTV) (CTV-Gd) and the T2-MRI-based CTV (CTV-T2) were defined as the contrast-enhanced area on Gd-MRI and the high intensity area on T2-MRI, respectively. We defined CTV x mm (x = 5, 10, 15, 20) as x mm outside the CTV. MET-PET-based CTV (CTV-MPET) was defined as the area of accumulation of MET-PET. We calculated the sensitivity and specificity of CTV-Gd and CTV-T2 following comparison with CTV-MPET, which served as the gold standard in this study.Results
The sensitivity of CTV-T2 5 mm (98%) was significantly higher than CTV-T2 (87%), and there was no significant difference in the sensitivity between CTV-T2 5 mm and CTV T2 10, 15, or 20 mm. The sensitivity of CTV-Gd 20 mm (97%) was lower than that of CTV-T2 5 mm (98%).Conclusions
A margin of at least 5 mm around the high intensity area on T2-MRI is necessary in the target volume delineation of recurrent glioblastoma for the coverage of MET-PET findings in re-radiation therapy planning. 相似文献174.
Yumi Yamanashi Migaku Teramoto Naruki Morimura Etsuko Nogami Satoshi Hirata 《Primates; journal of primatology》2018,59(2):145-152
Understanding how social relationships affect long-term stress is important because stress has a profound impact on the welfare of animals and social relationships often exert a strong influence on their stress responses. The purpose of this study was to investigate the relationship between social behaviors and long-term stress levels as assessed by hair cortisol (HC) concentration. The subjects were 11 chimpanzees living in an all-male group (divided into two sub-groups) in Kumamoto Sanctuary, Kyoto University, Japan. Behavioral data were collected between December 2014 and March 2015. The total observation time was 129 h. Hair samples were collected in late March and early April 2015, and cortisol was extracted from the hair and measured with enzyme immunoassay. The hair growth rate was estimated to be 1.33 ± 0.06 cm/month. The results revealed that there was a positive correlation between the rate of receiving aggression and HC levels. We also found a significant negative correlation between the balance between giving and receiving grooming (grooming balance index: GBI), which was calculated by subtracting the rate with which grooming is given from that with which it is received, and the rate of receiving aggression and between the GBI and HC levels. Thus, individuals receiving higher levels of aggression also tended to give grooming for relatively long periods compared to the time they were being groomed. In contrast, the rate of initiating aggression did not have a relationship with either HC levels or any measure of social grooming. We did not find social buffering effects, as there was no correlation between mutual social grooming and HC levels. These results show that not only aggressive interactions but also overall social situations in which animals do not have balanced relationships with others might result in the long-term elevation of cortisol levels in captive male chimpanzees. 相似文献
175.
Vonoprazan‐ vs proton‐pump inhibitor‐based first‐line 7‐day triple therapy for clarithromycin‐susceptible Helicobacter pylori: A multicenter,prospective, randomized trial 下载免费PDF全文
176.
Shen-Ying Zhang Nathaniel E. Clark Catherine A. Freije Elodie Pauwels Allison J. Taggart Satoshi Okada Hanna Mandel Paula Garcia Michael J. Ciancanelli Anat Biran Fabien G. Lafaille Miyuki Tsumura Aurélie Cobat Jingchuan Luo Stefano Volpi Bastian Zimmer Sonoko Sakata Alexandra Dinis Jean-Laurent Casanova 《Cell》2018,172(5):952-965.e18
177.
178.
179.
Teruyoshi Nagamitsu Kato Shuri Satoshi Kikuchi Shinsuke Koike Shoji Naoe Takashi Masaki 《Ecology and evolution》2019,9(19):11266-11276
Spatial genetic structure (SGS) of plants mainly depends on the effective population size and gene dispersal. Maternally inherited loci are expected to have higher genetic differentiation between populations and more intensive SGS within populations than biparentally inherited loci because of smaller effective population sizes and fewer opportunities of gene dispersal in the maternally inherited loci. We investigated biparentally inherited nuclear genotypes and maternally inherited chloroplast haplotypes of microsatellites in 17 tree populations of three wild cherry species under different conditions of tree distribution and seed dispersal. As expected, interpopulation genetic differentiation was 6–9 times higher in chloroplast haplotypes than in nuclear genotypes. This difference indicated that pollen flow 4–7 times exceeded seed flow between populations. However, no difference between nuclear and chloroplast loci was detected in within‐population SGS intensity due to their substantial variation among the populations. The SGS intensity tended to increase as trees became more aggregated, suggesting that tree aggregation biased pollen and seed dispersal distances toward shorter. The loss of effective seed dispersers, Asian black bears, did not affect the SGS intensity probably because of mitigation of the bear loss by other vertebrate dispersers and too few tree generations after the bear loss to alter SGS. The findings suggest that SGS is more variable in smaller spatial scales due to various ecological factors in local populations. 相似文献
180.
Zheng Wang Akira Sato Daiki Akiyama Taizo Kimura Kazuko Tajiri Tomoya Hoshi Satoshi Sakai Akira Koike Takashi Miyauchi Kazutaka Aonuma 《Life sciences》2014