全文获取类型
收费全文 | 75184篇 |
免费 | 6685篇 |
国内免费 | 2669篇 |
专业分类
84538篇 |
出版年
2023年 | 485篇 |
2022年 | 968篇 |
2021年 | 1653篇 |
2020年 | 1244篇 |
2019年 | 1451篇 |
2018年 | 1642篇 |
2017年 | 1269篇 |
2016年 | 1798篇 |
2015年 | 2698篇 |
2014年 | 3124篇 |
2013年 | 3541篇 |
2012年 | 4235篇 |
2011年 | 4063篇 |
2010年 | 2523篇 |
2009年 | 2345篇 |
2008年 | 2992篇 |
2007年 | 2785篇 |
2006年 | 2657篇 |
2005年 | 2230篇 |
2004年 | 2108篇 |
2003年 | 1884篇 |
2002年 | 1768篇 |
2001年 | 3422篇 |
2000年 | 3057篇 |
1999年 | 2351篇 |
1998年 | 929篇 |
1997年 | 831篇 |
1996年 | 764篇 |
1995年 | 646篇 |
1994年 | 649篇 |
1993年 | 518篇 |
1992年 | 1587篇 |
1991年 | 1429篇 |
1990年 | 1324篇 |
1989年 | 1257篇 |
1988年 | 1113篇 |
1987年 | 1071篇 |
1986年 | 939篇 |
1985年 | 938篇 |
1984年 | 703篇 |
1983年 | 611篇 |
1979年 | 703篇 |
1978年 | 520篇 |
1975年 | 557篇 |
1974年 | 650篇 |
1973年 | 606篇 |
1972年 | 627篇 |
1971年 | 584篇 |
1970年 | 546篇 |
1969年 | 553篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
An unusual case of neurofibrosarcoma of the cranio-orbital-maxillary region was resected by a combined neurosurgical and plastic surgical team. The resulting defect was reconstructed in one stage with a free rectus abdominis myocutaneous flap, obviating the need for subsequent prosthetic obturation of the maxillary defect. This reconstructive technique expedited the patient's convalescent period, allowing him to return to work 3 weeks following surgery. Wound healing was uneventful, and the cosmetic result was acceptable to the patient. 相似文献
92.
C. S. Lin M. C. Tseng P. I. Hong W. C. Chang 《In vitro cellular & developmental biology. Plant》2006,42(4):331-335
Summary Inflorescence proliferation is a plant tissue culture technique that, can be used to obtain in vitro inflorescences year-round without the intervening development of vegetative organs. In this study, we used albino mutant
inflorescences of Dendrocalamus latiflorus as the original explant material to investigate, the effect of plant growth regulators on long-term inflorescence proliferation.
The albino inflorescences proliferated on solidified Murashige and Skoog (MS) basal medium supplemented with thidiazuron (TDZ),
and the optimal concentration for successful long-term inflorescence proliferation was 0.45 μM TDZ. A combination of α-naphthaleneacetic acid (NAA) with 0.45 μM TDZ inhibited the inflorescence proliferation. Inflorescences cultured on a TDZ-free medium supplemented with 26.82 μM NAA rooted in 21 d, vegetative shoots formed by 42 d and, in one case, flowering occurred after 63 d. The auxins 2,4-dichlorophenoxyacetic
acid (2,4-D, 4.52 μM) and pieloram (4.14 μM) induced shoot formation. The protocol described can be used to produce large numbers of mutant inflorescences within a relatively
short period of time. 相似文献
93.
G. S. C. BUSO Z. P. S. AMARAL R. P. V. BRONDANI M. E. FERREIRA 《Molecular ecology resources》2006,6(1):252-254
Efforts to develop molecular tools for genetic analysis and breeding of common bean in the tropics are still limited. The number of microsatellite markers available for the crop is small compared to other crops of similar social and economic importance. As part of a project to broaden the use of molecular tools in bean breeding, a genomic library enriched for AG/TC repeat sequences was constructed for Phaseolus vulgaris. Twenty microsatellite markers were initially developed and 10 were characterized using a panel of 85 representative accessions of the bean gene bank. The number of alleles per marker ranged from three to 10. The polymorphism information content (PIC) varied from 0.23 to 0.80. The results indicate that the new markers can be readily used in genetically analysis of common bean. 相似文献
94.
S. M. Pershin E. Sh. Ismailov Z. G. Suleimanova Z. N. Abdulmagomedova D. Z. Zagirova 《Biophysics》2014,59(2):334-338
It has been experimentally established that cultivation of yeast cells in depleted, dietary or normal nutrient aqueous solutions enriched with ortho-H2O spin isomers is accompanied by an increase in the amount of carbon dioxide produced by the cells and an increase in their biomass. It has been revealed that the rate of metabolic processes and biological activity depends on the quality of nutrition and enhances in time in both nutrient solutions. In contrast, the reproductive function and the rate of cell division are insusceptible to the components of nutrition, but intensified in a solution enriched with ortho-H2O similar to retardation of aging. The observed effects are discussed in assumption that an increase of a portion of ortho-H2O molecules occurs in the neighborhood of water channels in the cell membrane that let through only monomers of H2O and determine the rate vicinity of metabolic processes. 相似文献
95.
96.
Z Jesenská I Sajbidorová 《Journal of hygiene, epidemiology, microbiology, and immunology》1991,35(1):41-49
The biodegradation of T-2 toxin was studied by strains of micromycetes which were isolated from the environment. The 26 tested strains were divided into three groups. Group contains strains which degraded T-2 toxin very fast. This toxin could not be chromatographically determined in the medium even after 48 hours of incubation and the antifungal activity of residua against Kluyveromyces fragilis CCY-51-1-2 was low or zero. There were strains of Alternaria sp., Ulocladium sp., Aspergillus candidus, Cladosporium cladosporioides, Rhodotorula sp., Aspergillus flavus and Cladosporium macrocarpum. Group II contains with a low activity and in group III the results were variable and non stable. 相似文献
97.
Abstract cDNA-RNA liquid hybridization analysis was used to compare the RNA sequence homology between two members of the Nudaurelia β virus family, Trichoplusia ni virus ( T.ni V) and Dasychira pudibunda virus ( D.p V). Heterologous hybridization experiments demonstrated that these viruses shared little sequence homology. Using oligo(dT) chromatography and oligo(dT)12–18 as a primer for cDNA synthesis it was shown that neither T.ni V nor D.p V RNA genomes possess a poly(A) tract at the 3' end. 相似文献
98.
In these studies we describe the production of three mAb raised to an idiotype on an IgG anticasein antibody isolated from the serum of one IgA-deficient blood donor. These are IgM kappa and block the binding of casein Ag to anticasein antibody. Sera of unrelated IgA-deficient donors were tested for the presence of the idiotype; 15 of 56 IgA-deficient sera (25%) contain the anticasein idiotype, whereas 1 of 45 normal sera was positive. Anticasein antibodies as a whole were predominantly of the IgG1 and IgG3 subclass; idiotype-positive anticaseins are predominantly of the IgG1 subclass. For IgA-deficient donors, the relative amount of idiotype-positive anticasein antibody was correlated with the level of anticasein present in the serum. Studies were done to investigate the potential inheritance of the idiotype in families; in three of four families the idiotype was inherited in an apparent autosomal dominant pattern. Our data show that a common cross-reactive idiotype can be detected in the sera of IgA-deficient individuals and their family members. This suggests that V region markers may be conserved in this humoral immunodeficiency disease. 相似文献
99.
100.