全文获取类型
收费全文 | 1866篇 |
免费 | 119篇 |
出版年
2022年 | 13篇 |
2021年 | 23篇 |
2020年 | 16篇 |
2019年 | 17篇 |
2018年 | 31篇 |
2017年 | 34篇 |
2016年 | 51篇 |
2015年 | 72篇 |
2014年 | 69篇 |
2013年 | 119篇 |
2012年 | 126篇 |
2011年 | 141篇 |
2010年 | 74篇 |
2009年 | 60篇 |
2008年 | 108篇 |
2007年 | 106篇 |
2006年 | 92篇 |
2005年 | 113篇 |
2004年 | 93篇 |
2003年 | 81篇 |
2002年 | 70篇 |
2001年 | 48篇 |
2000年 | 43篇 |
1999年 | 37篇 |
1998年 | 21篇 |
1997年 | 16篇 |
1996年 | 14篇 |
1995年 | 9篇 |
1994年 | 10篇 |
1993年 | 8篇 |
1992年 | 27篇 |
1991年 | 18篇 |
1990年 | 20篇 |
1989年 | 23篇 |
1988年 | 21篇 |
1987年 | 11篇 |
1986年 | 23篇 |
1985年 | 14篇 |
1984年 | 10篇 |
1983年 | 9篇 |
1982年 | 8篇 |
1981年 | 5篇 |
1980年 | 6篇 |
1979年 | 10篇 |
1978年 | 6篇 |
1977年 | 6篇 |
1975年 | 6篇 |
1973年 | 7篇 |
1971年 | 6篇 |
1968年 | 6篇 |
排序方式: 共有1985条查询结果,搜索用时 46 毫秒
61.
62.
63.
64.
65.
Jie Zhang Satoshi Yamada Eri Ogihara Masahiro Kurita Norihiro Banno Wei Qu Feng Feng Toshihiro Akihisa 《化学与生物多样性》2016,13(11):1601-1609
Seven triterpenoids, 1 – 7 , two diarylheptanoids, 8 and 9 , four phenolic compounds, 10 – 13 , and three other compounds, 14 – 16 , were isolated from the hexane and MeOH extracts of the bark of Myrica cerifera L. (Myricaceae). Among these compounds, betulin ( 1 ), ursolic acid ( 3 ), and myricanol ( 8 ) exhibited cytotoxic activities against HL60 (leukemia), A549 (lung), and SK‐BR‐3 (breast) human cancer cell lines (IC50 3.1 – 24.2 μm ). Compound 8 induced apoptotic cell death in HL60 cells (IC50 5.3 μm ) upon evaluation of the apoptosis‐inducing activity by flow cytometric analysis and by Hoechst 33342 staining method. Western blot analysis on HL60 cells revealed that 8 activated caspases‐3, ‐8, and ‐9 suggesting that 8 induced apoptosis via both mitochondrial and death receptor pathways in HL60. Upon evaluation of the melanogenesis‐inhibitory activity in B16 melanoma cells induced with α‐melanocyte‐stimulating hormone (α‐MSH), erythrodiol ( 7 ), 4‐hydroxy‐2‐methoxyphenyl β‐d ‐glucopyranoside ( 13 ), and butyl quinate ( 15 ) exhibited inhibitory effects (65.4 – 86.0% melanin content) with no, or almost no, toxicity to the cells (85.9 – 107.4% cell viability) at 100 μm concentration. In addition, 8 , myricanone ( 9 ), myricitrin ( 10 ), protocatechuic acid ( 11 ), and gallic acid ( 12 ) revealed potent DPPH radical‐scavenging activities (IC50 6.9 – 20.5 μm ). 相似文献
66.
Issei Ueda Shingo Kakeda Keita Watanabe Reiji Yoshimura Taro Kishi Osamu Abe Satoru Ide Junji Moriya Asuka Katsuki Hikaru Hori Nakao Iwata Jun Nakamura Yukunori Korogi 《PloS one》2016,11(3)
Background
Earlier studies implicated norepinephrine transporter (NET) gene (SLC6A2) polymorphisms in the etiology of major depressive disorder (MDD). Recently, two single nucleotide SLC6A2 polymorphisms, G1287A in exon 9 and T-182C in the promoter region, were found to be associated with MDD in different populations. We investigated the relationship between the brain volume and these two polymorphisms of the SLC6A2 in MDD patients.Methods
We obtained 3D high-resolution T1-weighted images of 30 first-episode MDD patients and 48 age- and sex-matched healthy subjects (HS). All were divided into 4 groups based on polymorphism of either the G1287A or the T-182C genotype. VBM analysis examined the effects of diagnosis, genotype, and genotype-diagnosis interactions.Results
Diagnosis effects on the brain morphology were found in the left superior temporal cortex. No significant genotype effects were found in the T-182C and the G1287A. A significant genotype (G1287A)–diagnosis interaction was found in the left dorsolateral prefrontal cortex. No significant genotype (T-182C)–diagnosis interaction effects were observed in any brain region.Conclusions
In MDD patients there seems to be a relationship between the volume of the dorsolateral prefrontal cortex and polymorphism of the SLC6A2 G1287A gene. 相似文献67.
Ren Matsuba Minako Imamura Yasushi Tanaka Minoru Iwata Hiroshi Hirose Kohei Kaku Hiroshi Maegawa Hirotaka Watada Kazuyuki Tobe Atsunori Kashiwagi Ryuzo Kawamori Shiro Maeda 《PloS one》2016,11(4)
AimWe performed a replication study in a Japanese population to evaluate the association between type 2 diabetes and six susceptibility loci (TMEM154, SSR1, FAF1, POU5F1, ARL15, and MPHOSPH9) originally identified by a transethnic meta-analysis of genome-wide association studies (GWAS) in 2014.MethodsWe genotyped 7,620 Japanese participants (5,817 type 2 diabetes patients and 1,803 controls) for each of the single nucleotide polymorphisms (SNPs) using a multiplex polymerase chain reaction invader assay. The association of each SNP locus with the disease was evaluated using logistic regression analysis.ResultsOf the six SNPs examined in this study, four (rs6813195 near TMEM154, rs17106184 in FAF1, rs3130501 in POU5F1 and rs4275659 near MPHOSPH9) had the same direction of effect as in the original reports, but two (rs9505118 in SSR1 and rs702634 in ARL15) had the opposite direction of effect. Among these loci, rs3130501 and rs4275659 were nominally associated with type 2 diabetes (rs3130501; p = 0.017, odds ratio [OR] = 1.113, 95% confidence interval [CI] 1.019–1.215, rs4275659; p = 0.012, OR = 1.127, 95% CI 1.026–1.238, adjusted for sex, age and body mass index), but we did not observe a significant association with type 2 diabetes for any of the six evaluated SNP loci in our Japanese population.ConclusionsOur results indicate that effects of the six SNP loci identified in the transethnic GWAS meta-analysis are not major among the Japanese, although SNPs in POU5F1 and MPHOSPH9 loci may have some effect on susceptibility to type 2 diabetes in this population. 相似文献
68.
Acceleration of genetic improvement of autogamous crops such as wheat and rice is necessary to increase cereal production in response to the global food crisis. Population and pedigree methods of breeding, which are based on inbred line selection, are used commonly in the genetic improvement of autogamous crops. These methods, however, produce a few novel combinations of genes in a breeding population. Recurrent selection promotes recombination among genes and produces novel combinations of genes in a breeding population, but it requires inaccurate single-plant evaluation for selection. Genomic selection (GS), which can predict genetic potential of individuals based on their marker genotype, might have high reliability of single-plant evaluation and might be effective in recurrent selection. To evaluate the efficiency of recurrent selection with GS, we conducted simulations using real marker genotype data of rice cultivars. Additionally, we introduced the concept of an “island model” inspired by evolutionary algorithms that might be useful to maintain genetic variation through the breeding process. We conducted GS simulations using real marker genotype data of rice cultivars to evaluate the efficiency of recurrent selection and the island model in an autogamous species. Results demonstrated the importance of producing novel combinations of genes through recurrent selection. An initial population derived from admixture of multiple bi-parental crosses showed larger genetic gains than a population derived from a single bi-parental cross in whole cycles, suggesting the importance of genetic variation in an initial population. The island-model GS better maintained genetic improvement in later generations than the other GS methods, suggesting that the island-model GS can utilize genetic variation in breeding and can retain alleles with small effects in the breeding population. The island-model GS will become a new breeding method that enhances the potential of genomic selection in autogamous crops, especially bringing long-term improvement. 相似文献
69.
Akiko Shibui Ayako Takamori Mohammed E.M. Tolba Aya Nambu Eri Shimura Sachiko Yamaguchi Chizu Sanjoba Hajime Suto Katsuko Sudo Ko Okumura Sumio Sugano Hideaki Morita Hirohisa Saito Kenji Matsumoto Susumu Nakae 《Biochemistry and Biophysics Reports》2016
IL-25, IL-33 and TSLP, which are produced predominantly by epithelial cells, can induce production of Th2-type cytokines such as IL-4, IL-5 and/or IL-13 by various types of cells, suggesting their involvement in induction of Th2-type cytokine-associated immune responses. It is known that Th2-type cytokines contribute to host defense against malaria parasite infection in mice. However, the roles of IL-25, IL-33 and TSLP in malaria parasite infection remain unclear. Thus, to elucidate this, we infected wild-type, IL-25?/?, IL-33?/? and TSLP receptor (TSLPR)?/? mice with Plasmodium berghei (P. berghei) ANKA, a murine malaria strain. The expression levels of IL-25, IL-33 and TSLP mRNA were changed in the brain, liver, lung and spleen of wild-type mice after infection, suggesting that these cytokines are involved in host defense against P. berghei ANKA. However, the incidence of parasitemia and survival in the mutant mice were comparable to in the wild-type mice. These findings indicate that IL-25, IL-33 and TSLP are not critical for host defense against P. berghei ANKA. 相似文献
70.