全文获取类型
收费全文 | 2564篇 |
免费 | 169篇 |
国内免费 | 1篇 |
专业分类
2734篇 |
出版年
2022年 | 11篇 |
2021年 | 23篇 |
2020年 | 12篇 |
2019年 | 17篇 |
2018年 | 23篇 |
2017年 | 23篇 |
2016年 | 42篇 |
2015年 | 63篇 |
2014年 | 79篇 |
2013年 | 153篇 |
2012年 | 140篇 |
2011年 | 127篇 |
2010年 | 85篇 |
2009年 | 106篇 |
2008年 | 129篇 |
2007年 | 140篇 |
2006年 | 146篇 |
2005年 | 189篇 |
2004年 | 184篇 |
2003年 | 175篇 |
2002年 | 185篇 |
2001年 | 61篇 |
2000年 | 49篇 |
1999年 | 40篇 |
1998年 | 44篇 |
1997年 | 21篇 |
1996年 | 24篇 |
1995年 | 38篇 |
1994年 | 35篇 |
1993年 | 23篇 |
1992年 | 31篇 |
1991年 | 30篇 |
1990年 | 19篇 |
1989年 | 27篇 |
1988年 | 25篇 |
1987年 | 20篇 |
1986年 | 19篇 |
1985年 | 20篇 |
1984年 | 10篇 |
1983年 | 19篇 |
1982年 | 18篇 |
1981年 | 18篇 |
1980年 | 11篇 |
1979年 | 8篇 |
1978年 | 12篇 |
1975年 | 7篇 |
1974年 | 6篇 |
1973年 | 8篇 |
1972年 | 4篇 |
1971年 | 6篇 |
排序方式: 共有2734条查询结果,搜索用时 15 毫秒
81.
Koshi Nakamura Masaru Sakurai Katsuyuki Miura Yuko Morikawa Shin-ya Nagasawa Masao Ishizaki Teruhiko Kido Yuchi Naruse Yasushi Suwazono Hideaki Nakagawa 《PloS one》2013,8(1)
Given the lack of economic studies evaluating the outcomes of smoking cessation programs from the viewpoint of program sponsors, we conducted a case study to provide relevant information for worksites. The present study was carried out between 2006 and 2008 at a manufacturing factory in the Toyama Prefecture of Japan and included subjects who voluntarily entered a smoking cessation program. The program included face-to-face counselling followed by weekly contact to provide encouragement over six months using e-mail or inter-office mail. Nicotine patches were available if required. All 151 participants stopped smoking immediately. Over the 24-month study period, self-report showed 49.7% abstained continuously from smoking. The rate of 24-month consecutive abstinence was higher in participants with lower Fagerström Test scores for Nicotine Dependence at baseline than in those with higher scores (63.6% for 0–2 points vs. 46.5% for 3–6 points vs. 43.8% for 7–10 points; chi-square test p = 0.19). A logistic regression model showed a significant linear trend for the association between the score and abstinence status after adjustment for possible confounding factors (p = 0.03). The crude incremental cost for one individual to successfully quit smoking due to the support program was ¥46,379 (i.e., ¥100 = $1.28, £0.83, or €1.03 at foreign exchange rates). The corresponding costs for the three categories of the Fagerström Test score for Nicotine Dependence were ¥31,953, ¥47,450 and ¥64,956, respectively. When a sensitivity analysis was conducted based on the 95% confidence interval of the success rate, the variance in the corresponding costs was ¥25,514–45,034 for 0–2 points, ¥38,344–61,824 for 3–6 points, and ¥45,698–108,260 for 7–10 points. The degree of nicotine dependence may therefore be an important determinant of the cost-effectiveness of smoking cessation programs. 相似文献
82.
King-Wah Chiu Toshiaki Nakano Kuang-Den Chen Chia-Yun Lai Li-Wen Hsu Ho-Ching Chiu Ching-Yin Huang Yu-Fan Cheng Shigeru Goto Chao-Long Chen 《PloS one》2013,8(8)
This study used pyrosequencing to determine the proportional distribution of CYP3A5*3 genotypes to further confirm the homogeneous phenomenon that is observed when recipients and donors in living donor liver transplantation (LDLT) have a different single nucleotide polymorphism (SNP) genotype. We enrolled 42 recipient/living donor pairs and the SNPs of CYP3A5*3 were identified by polymerase chain reaction-restriction fragment length polymorphism. We performed 120 liver graft biopsies as part of clinical investigations after LDLT. Pyrosequencing of the CYP3A5*3 SNPs revealed that among the 16 recipients with the G/G genotype, 94.68% had the G and 5.32% the A allele. Among the 14 recipients with the A/G genotype, 78.08% had the G and 21.92% the A allele, and among the 12 recipients with the A/A genotype, 18.45% had the G and 81.55% the A allele. Among the 12 donors with the G/G genotype, 93.85% had the G and 6.14% the A allele. Among the 26 donors with the A/G genotype, 75.73% had the G and 24.27% the A allele, and among the 4 donors with the A/A genotype, 11.09% had the G and 88.91% the A allele. There were a total of 120 liver graft biopsy samples; among the 37 recipients with the G/G genotype, 89.74% had the G and 10.26% the A allele, among the 70 recipients with the A/G genotype, 71.57% had the G and 28.43% the A allele, and among the 13 recipients with the A/A genotype, 48.25% had the G and 51.75% the A allele. The proportional distribution of G and A alleles of the CYP3A5*3 SNP between recipients/donors and liver grafts after LDLT was significantly different (p<0.001). Pyrosequencing was useful in identifying detailed proportional changes of the CYP3A5*3 SNP allele distribution, and to confirm the homogeneous phenomenon when recipients and donors in LDLT have a different genotype. 相似文献
83.
Yoshisada Fujiwara Toshiaki Higashikawa Mariko Tatsumi 《Journal of cellular physiology》1977,92(3):365-374
We investigated the cloning efficiency, DNA repair, and the rate of DNA replication in the skin fibroblasts from patients with Werner's syndrome (WS) of an autosomal recessive premature aging disease. Five WS strains exhibited normal levels of sensitivity toward X-ray and UV killings and repair of X-ray induced single strand breaks of DNA (rejoining) and UV damage to DNA (unscheduled DNA synthesis). The sedimentation of newly synthesizing DNA in alkaline sucrose gradients demonstrated a characteristic feature that only the elongation rate of DNA chains, estimated by the molecular weight increase, was significantly slower during early passages in WS cells than in normal Hayflick Phase II fibroblasts. In addition, plating efficiencies as well as the replicative potentials of five WS strains were more limited than those of normal cells under the identical culture conditions. It seems therefore that at least in the WS cells tested, the slow rate of DNA replication may be more related to the shortened lifespan and enhanced cell death, as manifestation of premature senescence at the cellular level, than be the DNA repair ability. 相似文献
84.
Ohtake Y Sato T Matsuoka H Nishimoto M Taka N Takano K Yamamoto K Ohmori M Higuchi T Murakata M Kobayashi T Morikawa K Shimma N Suzuki M Hagita H Ozawa K Yamaguchi K Kato M Ikeda S 《Bioorganic & medicinal chemistry》2011,19(18):5334-5341
5a-Carba-β-D-glucopyranose derivatives were synthesized and identified as novel SGLT2-selective inhibitors. These inhibitors exhibited potent SGLT2 inhibition with high selectivity over SGLT1. Among the tested compounds, 6f indicated the most potent hSGLT2 inhibition and the highest selectivity over hSGLT1. Moreover, the pharmacokinetics data also showed that 6h, which had the same aglycon structure as sergliflozin-active (3-active), had a threefold longer half-life time (T(1/2)) than sergliflozin (3) with a high distribution volume in db/db mice. Subsequently, 6h lowered blood glucose levels as much as 3 and showed longer hypoglycemic action than 3 in db/db mice. 相似文献
85.
Nakazawa H Okada K Kobayashi R Kubota T Onodera T Ochiai N Omata N Ogasawara W Okada H Morikawa Y 《Applied microbiology and biotechnology》2008,81(4):681-689
The genes encoding the catalytic domains (CD) of the three endoglucanases (EG I; Cel7B, EG II; Cel5A, and EG III; Cel12A)
from Trichoderma reesei QM9414 were expressed in Escherichia coli strains Rosetta-gami B (DE3) pLacI or Origami B (DE3) pLacI and were found to produce functional intracellular proteins.
Protein production by the three endoglucanase transformants was evaluated as a function of growth temperature. Maximal productivity
of EG I-CD at 15°C, EG II-CD at 20°C and EG III at 37°C resulted in yields of 6.9, 72, and 50 mg/l, respectively. The endoglucanases
were purified using a simple purification method based on removing E. coli proteins by isoelectric point precipitation. Specific activity toward carboxymethyl cellulose was found to be 65, 49, and
15 U/mg for EG I-CD, EG II-CD, and EG III, respectively. EG II-CD was able to cleave 1,3–1,4-β-d-glucan and soluble cellulose derivatives. EG III was found to be active against cellulose, 1,3–1,4-β-d-glucan and xyloglucan, while EG I-CD was active against cellulose, 1,3–1,4-β-d-glucan, xyloglucan, xylan, and mannan. 相似文献
86.
Ueki Atsuko Takehara Toshiaki Ishioka Gen Kaku Nobuo Ueki Katsuji 《Applied microbiology and biotechnology》2017,101(22):8267-8277
Applied Microbiology and Biotechnology - Biological soil disinfestation (BSD) involves elimination of soil-borne plant pathogens in an environmentally friendly manner. Two anaerobic bacterial... 相似文献
87.
Endosymbiotic Bacteroidales Bacteria of the Flagellated Protist Pseudotrichonympha grassii in the Gut of the Termite Coptotermes formosanus 下载免费PDF全文
Satoko Noda Toshiya Iida Osamu Kitade Hideaki Nakajima Toshiaki Kudo Moriya Ohkuma 《Applied microbiology》2005,71(12):8811-8817
A unique lineage of bacteria belonging to the order Bacteroidales was identified as an intracellular endosymbiont of the protist Pseudotrichonympha grassii (Parabasalia, Hypermastigea) in the gut of the termite Coptotermes formosanus. We identified the 16S rRNA, gyrB, elongation factor Tu, and groEL gene sequences in the endosymbiont and detected a very low level of sequence divergence (<0.9% of the nucleotides) in the endosymbiont population within and among protist cells. The Bacteroidales endosymbiont sequence was affiliated with a cluster comprising only sequences from termite gut bacteria and was not closely related to sequences identified for members of the Bacteroidales attached to the cell surfaces of other gut protists. Transmission electron microscopy showed that there were numerous rod-shaped bacteria in the cytoplasm of the host protist, and we detected the endosymbiont by fluorescence in situ hybridization (FISH) with an oligonucleotide probe specific for the 16S rRNA gene identified. Quantification of the abundance of the Bacteroidales endosymbiont by sequence-specific cleavage of rRNA with RNase H and FISH cell counting revealed, surprisingly, that the endosymbiont accounted for 82% of the total bacterial rRNA and 71% of the total bacterial cells in the gut community. The genetically nearly homogeneous endosymbionts of Pseudotrichonympha were very abundant in the gut symbiotic community of the termite. 相似文献
88.
Goro?HANYAEmail author Miki?MATSUBARA Hideki?SUGIURA Sachiko?HAYAKAWA Shunji?GOTO Toshiaki?TANAKA Joseph?SOLTIS Naohiko?NOMA 《Ecological Research》2004,19(2):179-188
The mass mortality of wild Japanese macaques (Macaca fuscata Blyth) was observed in a warm temperate forest of Yakushima, southern Japan. Demographic changes of eight troops between August 1998 and August 1999 were studied and 56% of macaques disappeared from the five intensively studied troops. Mortality varied among troops: two troops became extinct, while another troop did not decrease in size. The rate of mortality of the other troops was between 33 and 80%. The variation in mortality among the troops was either the outcome of local concentrations of mortality or of intertroop competition. The rate of mortality decreased with increasing distance from the two extinct troops and with increasing troop size; these two factors could not be separated statistically. The direct cause of death was diagnosed as pneumonia for four out of five fresh carcasses. The fleshy fruit production in autumn 1998 was the lowest in 14years, and macaques had relied on leaves earlier than in usual years. It was exceptionally hot and dry in the summer of 1998. The exceptionally poor fruit production and hot summer of this year, with the resulting shortage of high-quality foods, was consistent with the scenario that mass mortality was due to the poor nutritional conditions. However, the possibility that epidemics caused the mass mortality cannot be ruled out. Our findings proved that primates in a seemingly stable habitat experience fluctuations in demographic parameters under natural conditions. 相似文献
89.
It is known that several naturally occurring substances known as osmolytes increase the conformational stability of proteins. Bolen and co-worker proposed the osmophobic theory, which asserts the osmolyte effect occurs because of an unfavorable interaction of osmolytes mainly with the protein backbone, based on the results on the transfer Gibbs energy of amino acids (Deltag) [Bolen and Baskakov (2001) J. Mol. Biol. 310, 955-963]. In this paper, we report the effect of sarcosine on the conformational stability (DeltaG) of RNase Sa (96 residues and one disulfide bond) and four mutant proteins. The thermal denaturation curves for RNase Sa in sarcosine fitted a two-state model on nonlinear least-squares analysis. All the RNase Sa proteins were stabilized by sarcosine. For example, the increase in stability of the wild-type protein in 4 M sarcosine due to the osmolyte effect (Delta(o)DeltaG) is 3.2 kcal/mol. Mutational analysis of the osmolyte effect indicated that the changed Delta(o)DeltaG values upon mutation (Delta(m)Delta(o)DeltaG), as estimated from the Deltag values, are similar to the experimental values. Structural-based analysis of the osmolyte effect was also performed using model denatured structures: (a) a fully extended model (single chain) with no disulfide bond, (b) two-part, unfolded models (two chains) with a disulfide bond constructed through molecular dynamic (MD) simulation, and (c) a two-part, folded model (two chains). The two-part, unfolded models were expected to be more suitable as denatured structures. The Delta(o)DeltaG values calculated using the two-part, unfolded models were more consistent with experimental values than those calculated using the fully extended and two-part, folded models. This suggests that MD simulation is useful for testing denatured structures. These results indicate that the osmophobic theory can explain the osmolyte effect on protein stability. 相似文献
90.
Odaka K Aoki I Moriya J Tateno K Tadokoro H Kershaw J Minamino T Irie T Fukumura T Komuro I Saga T 《PloS one》2011,6(10):e25487