首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   460篇
  免费   38篇
  国内免费   1篇
  2022年   3篇
  2021年   3篇
  2020年   4篇
  2019年   1篇
  2018年   5篇
  2017年   3篇
  2016年   6篇
  2015年   15篇
  2014年   12篇
  2013年   20篇
  2012年   33篇
  2011年   28篇
  2010年   18篇
  2009年   12篇
  2008年   26篇
  2007年   33篇
  2006年   33篇
  2005年   28篇
  2004年   38篇
  2003年   41篇
  2002年   38篇
  2001年   14篇
  2000年   12篇
  1999年   2篇
  1998年   4篇
  1997年   7篇
  1996年   4篇
  1995年   2篇
  1994年   1篇
  1993年   1篇
  1992年   7篇
  1991年   5篇
  1990年   6篇
  1989年   7篇
  1988年   7篇
  1987年   3篇
  1986年   1篇
  1985年   3篇
  1984年   4篇
  1983年   3篇
  1982年   1篇
  1980年   1篇
  1977年   1篇
  1974年   2篇
  1973年   1篇
排序方式: 共有499条查询结果,搜索用时 603 毫秒
381.
382.
Obesity is a complex trait reflecting numerous genetic and environmental factors. Recently, a common genetic polymorphism (rs7566605) associated with a higher BMI was found in proximity to the insulin induced protein 2 (INSIG2 ) gene, with replication in four unrelated populations living in Western countries. We investigated the susceptibility to the polymorphism amongst the general Japanese population (n = 1976). The frequency of appearance of the single-nucleotide polymorphism (SNP) in the Japanese (G allele; 0.652, C allele; 0.348) was not different from that found in subjects of European origin as reported previously. However, the BMI levels in each of these genotypes did not differ significantly (GG; 23 +/- 3, GC; 24 +/- 3, CC; 24 +/- 3 kg/m(2), P = 0.906). In a separate analysis according to sex (male; P = 0.462, female; P = 0.879), age decade (40s; P = 0.057, 50s; P = 0.998, 60s; P = 0.622, 70s; 0.425, respectively), and tertiles of the BMI (1st; P = 0.409, 2nd; P = 0.088, 3rd; P = 0.780), the differences did not achieve statistical significance. The frequency of obesity did not differ among the genotypes (25 kg/m(2); 30.3, 30.8, 28.2%, P = 0.729, 30 kg/m(2); 2.9, 3.8, 2.8%, P = 0.549). No associations were also observed for related plasma markers; high-molecular weight (HMW) adiponectin (P = 0.510), high-sensitive C-reactive protein (P = 0.788), resistin (P = 0.937) and homeostasis of minimal assessment of insulin resistance (P = 0.634). These results indicate a lack of association between SNP rs7566605 and being overweight among the Japanese (in the middle-aged and elderly population).  相似文献   
383.
384.
385.
Benzo[a]pyrene (BaP), an environmental carcinogen, shows genotoxicity after metabolic transformation into the bay-region diol epoxide, BaP-7,8-diol 9,10-epoxide. 10-Azabenzo[a]pyrene (10-azaBaP), in which a ring nitrogen is located in the bay-region, is also a carcinogen and shows mutagenicity in the Ames test in the presence of the rat liver microsomal enzymes. In order to evaluate the effect of aza-substitution on in vivo genotoxicity, BaP and 10-azaBaP were assayed for their in vivo mutagenicity using the lacZ-transgenic mouse (Muta™Mouse). BaP was potently mutagenic in all of the organs examined (liver, lung, kidney, spleen, forestomach, stomach, colon, and bone marrow), as described in our previous report, whereas, 10-azaBaP was slightly mutagenic only in the liver and colon. The in vitro mutagenicities of BaP and 10-azaBaP were evaluated by the Ames test using liver homogenates prepared from several sources, i.e. CYP1A-inducer-treated rats, CYP1A-inducer-treated and non-treated mice, and humans. BaP showed greater mutagenicities than 10-azaBaP in the presence of a liver homogenate prepared from CYP1A-inducer-treated rodents. However, 10-azaBaP showed mutagenicities similar to or more potent than BaP in the presence of a liver homogenate or S9 from non-treated mice and humans. These results indicate that 10-aza-substitution markedly modifies the nature of mutagenicity of benzo[a]pyrene in both in vivo and in vitro mutagenesis assays.  相似文献   
386.
Surfactant protein B (SP-B) is known to promote surfactant phospholipid film formation and reduce surface tension. Native SP-B is a homodimer in which subunit association is stabilized via covalent linkage through cysteine 48. We hypothesized that loss of the intersubunit bridge would alter SP-B function and lead to increased inflammation in response to challenge by hyperoxia or endotoxin. Transgenic mice in which SP-B cysteine 48 was mutated to serine were generated and crossed into the SP-B(-/-) background. Wild-type mice and transgenic mice carrying a single copy (SP-Bmon(+)) or two copies (SP-Bmon(++)) of the transgene were exposed to 95% O2 for 3 days or intratracheally injected with 10 microg of endotoxin. Interleukin-1beta, major intrinsic protein 2, and interleukin-6 in lung homogenates after 3 days of hyperoxia were significantly higher (P < 0.001) in SP-Bmon(+) mice than SP-Bmon(++) or wild-type mice. At 16 h after endotoxin injection, cytokines in lung tissues were higher in SP-Bmon(+) mice compared with wild-type mice (P < 0.05). Consistent with prolonged recovery in SP-Bmon(+) mice, the percentage of apoptotic cells in alveolar lavage was significantly lower in SP-Bmon(+) mice than in SP-Bmon(++) and wild-type mice. Overall, increased inflammation in SP-Bmon(+) mice was corrected to a large extent by increased gene dosage, indicating that formation of the intersubunit disulfide bridge is not critical for SP-B function.  相似文献   
387.
The nucleotide sequence of the entire genome of a filamentous cyanobacterium, Anabaena sp. strain PCC 7120, was determined. The genome of Anabaena consisted of a single chromosome (6,413,771 bp) and six plasmids, designated pCC7120alpha (408,101 bp), pCC7120beta (186,614 bp), pCC7120gamma (101,965 bp), pCC7120delta (55,414 bp), pCC7120epsilon (40,340 bp), and pCC7120zeta (5,584 bp). The chromosome bears 5368 potential protein-encoding genes, four sets of rRNA genes, 48 tRNA genes representing 42 tRNA species, and 4 genes for small structural RNAs. The predicted products of 45% of the potential protein-encoding genes showed sequence similarity to known and predicted proteins of known function, and 27% to translated products of hypothetical genes. The remaining 28% lacked significant similarity to genes for known and predicted proteins in the public DNA databases. More than 60 genes involved in various processes of heterocyst formation and nitrogen fixation were assigned to the chromosome based on their similarity to the reported genes. One hundred and ninety-five genes coding for components of two-component signal transduction systems, nearly 2.5 times as many as those in Synechocystis sp. PCC 6803, were identified on the chromosome. Only 37% of the Anabaena genes showed significant sequence similarity to those of Synechocystis, indicating a high degree of divergence of the gene information between the two cyanobacterial strains.  相似文献   
388.
Diesel exhaust particles (DEPs) are particulate matter from diesel exhaust that contain many toxic compounds, such as polyaromatic hydrocarbons (PAHs). Some toxicities of PAH are thought to be expressed via aryl hydrocarbon receptors (AhRs). The male reproductive toxicity of DEPs might depend on AhR activation induced by PAHs. We hypothesized that AhR antagonists protect against the male reproductive toxicity of DEPs. Quercetin is a flavonoid and a well-known AhR antagonist, while onion contains many flavonoids, including quercetin. Hence, we examined whether quercetin and onion have alleviative effects against the male reproductive toxicity induced by DEPs. BALB/c male mice were fed quercetin- or onion-containing diets and received 10 injections of DEP suspension or vehicle into the dorsal subcutaneous layer over 5 weeks. The mice were euthanized at 2 weeks, after the last treatment, and their organs were collected. Daily sperm production and total incidence of sperm abnormalities were significantly affected in the DEP groups as compared with the vehicle group, but the total incidence of sperm abnormalities in the quercetin + DEP-treated mice was significantly reduced as compared with the DEP-treated mice. The numbers of Sertoli cells were significantly decreased in DEP-treated mice as compared with the vehicle-treated mice, but, the numbers of Sertoli cells were significantly increased in the quercetin and the onion + DEP-treated mice as compared with the DEP-treated mice. These results clearly indicate alleviative effects of quercetin and onion against the male reproductive toxicity induced by DEP.  相似文献   
389.
390.
A collection of 5006 full-length (FL) cDNA sequences was developed in barley. Fifteen mRNA samples from various organs and treatments were pooled to develop a cDNA library using the CAP trapper method. More than 60% of the clones were confirmed to have complete coding sequences, based on comparison with rice amino acid and UniProt sequences. Blastn homologies (E<1E-5) to rice genes and Arabidopsis genes were 89 and 47%, respectively. Of the 5028 possible amino acid sequences derived from the 5006 FLcDNAs, 4032 (80.2%) were classified into 1678 GreenPhyl multigenic families. There were 555 cDNAs showing low homology to both rice and Arabidopsis. Gene ontology annotation by InterProScan indicated that many of these cDNAs (71%) have no known molecular functions and may be unique to barley. The cDNAs showed high homology to Barley 1 GeneChip oligo probes (81%) and the wheat gene index (84%). The high homology between FLcDNAs (27%) and mapped barley expressed sequence tag enabled assigning linkage map positions to 151–233 FLcDNAs on each of the seven barley chromosomes. These comprehensive barley FLcDNAs provide strong platform to connect pre-existing genomic and genetic resources and accelerate gene identification and genome analysis in barley and related species.Key words: full-length cDNA, Hordeum vulgare, mRNA, gene ontology  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号