全文获取类型
收费全文 | 14261篇 |
免费 | 847篇 |
国内免费 | 3篇 |
出版年
2022年 | 34篇 |
2021年 | 159篇 |
2020年 | 96篇 |
2019年 | 125篇 |
2018年 | 178篇 |
2017年 | 175篇 |
2016年 | 276篇 |
2015年 | 433篇 |
2014年 | 525篇 |
2013年 | 982篇 |
2012年 | 897篇 |
2011年 | 898篇 |
2010年 | 606篇 |
2009年 | 556篇 |
2008年 | 907篇 |
2007年 | 956篇 |
2006年 | 865篇 |
2005年 | 889篇 |
2004年 | 873篇 |
2003年 | 787篇 |
2002年 | 759篇 |
2001年 | 184篇 |
2000年 | 181篇 |
1999年 | 242篇 |
1998年 | 209篇 |
1997年 | 152篇 |
1996年 | 137篇 |
1995年 | 124篇 |
1994年 | 125篇 |
1993年 | 113篇 |
1992年 | 149篇 |
1991年 | 114篇 |
1990年 | 127篇 |
1989年 | 122篇 |
1988年 | 87篇 |
1987年 | 98篇 |
1986年 | 90篇 |
1985年 | 79篇 |
1984年 | 76篇 |
1983年 | 63篇 |
1982年 | 87篇 |
1981年 | 66篇 |
1980年 | 68篇 |
1979年 | 47篇 |
1978年 | 48篇 |
1977年 | 44篇 |
1976年 | 45篇 |
1975年 | 52篇 |
1974年 | 33篇 |
1973年 | 33篇 |
排序方式: 共有10000条查询结果,搜索用时 621 毫秒
991.
992.
993.
Okada Anzu Okada Takashi Ide Takeshi Itoh Mituaki Tanaka Kunisuke Takaiwa Fumio Toriyama Kinya 《Molecular breeding : new strategies in plant improvement》2003,12(1):61-70
Recombinant Cry j 1, a Japanese cedar pollen allergen, was produced in rice seeds for potential use for oral immunotherapy. Cry j 1 cDNA was divided into two parts, an N-terminal half and a C-terminal half, and each was fused downstream to glutelin GluB-1 gene containing sequences of the promoter, 5 untranslated region and signal peptide. A gene for green fluorescent protein was also fused to the 3 end of the Cry j 1 fragment. Recombinant Cry j 1 of up to 16.6 g per mg total protein of the seeds was expressed in transgenic rice seeds. Although the recombinant Cry j 1 was expected to be accumulated in protein body II because of the employment of glutelin signal peptide, it was demonstrated to be accumulated exclusively in protein body I. The recombinant Cry j 1 was not shown to react with IgE of allergic patients, indicating the reduction of the risk of anaphylactic reaction. These results demonstrate that the transgenic rice seeds with the recombinant Cry j 1 would be useful for the study of oral immunotherapy. 相似文献
994.
Novel 16S rRNA introns were detected in four new strains within the family Thermoproteaceae. Pyrobaculum oguniense TE7(T) and Thermoproteus sp. IC-062 housed introns of 32 and 665-668 bp after positions 1205 and 1213 ( Escherichia coli numbering system), respectively. Caldivirga maquilingensis IC-167(T) had two introns of 37 and 140 bp after positions 901 and 908, respectively. Vulcanisaeta distributa IC-065 had a 691-bp intron after position 1391. All the introns larger than 650 bp encoded the LAGLI-DADG type proteins. The intron-encoded proteins of P. oguniense TE7(T) and Thermoproteus sp. IC-062 are cognate with the proteins encoded by introns inserted at the same position in other Pyrobaculum/ Thermoproteus strains and phylotypes. The intron-encoded protein of V. distributa IC-065 is partially related to that of a Pyrobaculum phylotype. A large-scale deletion in the second intron of Caldivirga maquilingensis IC-167(T) is suspected. Based on these newly found introns and hitherto known 16S rRNA introns, the evolutionary movements of the 16S rRNA introns and the encoded LAGLI-DADG type proteins are discussed. 相似文献
995.
Non-canonical Wnt signals similar to planar cell polarity (PCP) signaling in the fly control convergent extension (CE) of the dorsal mesoderm during gastrulation in vertebrates. Using the Ciona complete genome sequence and EST sequence data, we present here an initial and exhaustive search in non-vertebrate chordates, Ciona intestinalis for the family members as well as homologs or orthologs that are involved in PCP/CE signaling cascades. We clarified 7 cardinal gene families, including the MAPK, STE20 group kinase, Rho small GTPase, STAT, Glypican, Fz and Wnt gene families, as well as gene homologs or orthologs for known PCP/CE signaling components with their phylogenetic nature. As a result, we characterized 62 Ciona component genes. Among them, 59 genes were novel and functional genes which were supported by EST expressions and 15 genes belonged to PCP/CE component orthologs of other organisms or common ancestor genes. Moreover, from the phylogenetic point of view, we compared these components genome-widely with the PCP signaling components of fly and the CE signaling components of vertebrates. We then discovered not only that ascidians contain the basic ancestral signaling pathway components in chordates but also that several signaling components have not found in ascidian, indicating that ascidian CE pathway might have several gaps from vertebrate CE pathway. The present study provides an initial step for the subsequent analysis of CE in the non-vertebrate chordates, ascidians. In addition, this phylogenetic approach will help to facilitate understanding of the relationship between fly PCP signaling and the vertebrate CE pathway. 相似文献
996.
Hohdatsu T Yamazaki A Yamada M Kusuhara H Kaneshima T Koyama H 《Microbiology and immunology》2003,47(10):765-773
In the host defense mechanism against feline immunodeficiency virus (FIV) infection, CD8(+) T cells specifically attack virus-infected cells and suppress the replication of the virus in a non-cytolytic manner by secreting soluble factors. In this study, we measured CD8(+) T cell anti-FIV activity in 30 FIV-infected cats. We investigated its relationship with the number of peripheral blood lymphocytes, particularly the CD4(+) T cell and CD8(+) T cell counts, and the relationship between anti-FIV activity and the number of T cells of CD8alpha(+)beta(lo) and CD8alpha(+)beta(-) phenotypes. A clearly significant correlation was observed between anti-FIV activity and the number of CD4(+) T cells. A weaker anti-FIV activity was associated with a greater decrease in the number of CD4(+) T cells. However, there was no significant correlation between anti-FIV activity and the number of B or CD8(+) T cells. Compared with SPF cats, FIV-infected cats had significantly higher CD8alpha(+)beta(lo) T cell and CD8alpha(+)beta(-) T cell counts, but, no significant correlation was observed between these cell counts and anti-FIV activity. This anti-FIV activity significantly correlated with plasma viremia, which was detected in cats with a weak anti-FIV activity. These results suggest that the anti-FIV activity of CD8(+) T cells plays an important role in plasma viremia and the maintenance of CD4(+) T cells in the body. It is unlikely that CD8alpha(+)beta(lo) or CD8alpha(+)beta(-) T cells appearing after FIV infection represent a phenotype of CD8(+) cells with anti-FIV activity. 相似文献
997.
Li Y Kawamura Y Fujiwara N Naka T Liu H Huang X Kobayashi K Ezaki T 《Systematic and applied microbiology》2003,26(4):523-528
Classification of strain W3-B1, which was isolated from condensation water in the Russian space laboratory Mir, was investigated by a polyphasic taxonomic approach. Cells of strain W3-B1 were nonmotile, asporogenous, gram-negative slender rods with rounded ends. 16S rRNA gene sequence analysis indicated that organism should be placed in the genus Chryseobacterium. This organism contains menaquinone MK-6 as the predominent isoprenoid quinone and 3-OH iso 17:0 (40%), iso 15:0 (33%) as the major fatty acids. Phylogenetically, the nearest relative of strain W3-B1 is Chryseobacterium meningosepticum with sequence similarity of 98.4%, but DNA-DNA hybridization resulted in similarity values of only 52.3%. The G+C mol% is 34.6 mol%. Based upon results obtained by morphological, biochemical, chemotaxonomic, and molecular methods, strain W3-B1 was clearly distinguishable from other Chryseobacterium species. For these reasons, a novel species of family Flavobacteriaceae is proposed; strain W3-B1(T) (= GTC 862(T) = JCM 11413(T) = DSM 14571(T)) is the type strain. 相似文献
998.
Objectives: This study was designed to determine the factors influencing eating ability of old in‐patients in a rehabilitation hospital. Design: Cross‐sectional investigation. Setting: Forty‐six in‐patients in the rehabilitation ward of Hashimoto Hospital in Kagawa Prefecture in Japan were investigated using a multi‐disciplinary approach. Main outcome measures: Age, gender, state of dentition, muscle activity of lip, cheek and tongue, biting force, salivary flow rate per a minute (SFR), masticatory ability for gummy jelly, swallowing ability, texture of meal, independency of walking (Functional Independence Measure=FIM) and ability to communicate. Results: Bivariate analysis for the relationship between surveyed items and masticatory ability (chi‐square test) identified that better masticatory ability for gummy jelly was associated with age (<85 years), gender (male), state of dentition (dentate), SFR (high), activity of lip (good), biting force (high), swallowing ability (good) and activity of communication (high). Among these items, SFR (p=0.001), gender (p=0.004), ability to communicate (p=0.005) and age (p=0.012) were found having an influence on the masticatory ability (logistic regression analysis). On the other hand, age (<85years), gender (male), SFR (high), activity of lip (good), activity of cheek (good), biting force (high), masticatory ability (good) and swallowing ability (good) had a relationship with normal texture of meal. In regression analysis, only two items, activity of lip (p=0.003) and swallowing ability (p=0.024) emerged as factors on texture of meal. Conclusions: Masticatory ability for gummy jelly was influenced by cognitive function and was excluded from the factors on the state of meal. These results suggested the limitation of evaluation using test food, so dentists should observe eating behaviour of in‐patients. In addition, dentists should pay attention to the activity of the lip and swallowing ability as well as dentition and prostheses in the rehabilitation of eating ability. As SFR was the most significant factor on masticatory ability, this emphasizes the necessity of care for dry mouth caused by side effects of multi‐medication 相似文献
999.
A number of genes have been identified as members of the Argonaute family in various nonhuman organisms and these genes are considered to play important roles in the development and maintenance of germ-line stem cells. In this study, we identified the human Argonaute family, consisting of eight members. Proteins to be produced from these family members retain a common architecture with the PAZ motif in the middle and Piwi motif in the C-terminal region. Based on the sequence comparison, eight members of the Argonaute family were classified into two subfamilies: the PIWI subfamily (PIWIL1/HIWI, PIWIL2/HILI, PIWIL3, and PIWIL4/HIWI2) and the eIF2C/AGO subfamily (EIF2C1/hAGO1, EIF2C2/hAGO2, EIF2C3/hAGO3, and EIF2C4/hAGO4). PCR analysis using human multitissue cDNA panels indicated that all four members of the PIWI subfamily are expressed mainly in the testis, whereas all four members of the eIF2C/AGO subfamily are expressed in a variety of adult tissues. Immunoprecipitation and affinity binding experiments using human HEK293 cells cotransfected with cDNAs for FLAG-tagged DICER, a member of the ribonuclease III family, and the His-tagged members of the Argonaute family suggested that the proteins from members of both subfamilies are associated with DICER. We postulate that at least some members of the human Argonaute family may be involved in the development and maintenance of stem cells through the RNA-mediated gene-quelling mechanisms associated with DICER. 相似文献