全文获取类型
收费全文 | 17095篇 |
免费 | 949篇 |
国内免费 | 952篇 |
出版年
2024年 | 48篇 |
2023年 | 225篇 |
2022年 | 276篇 |
2021年 | 378篇 |
2020年 | 387篇 |
2019年 | 452篇 |
2018年 | 508篇 |
2017年 | 362篇 |
2016年 | 379篇 |
2015年 | 431篇 |
2014年 | 772篇 |
2013年 | 1101篇 |
2012年 | 625篇 |
2011年 | 778篇 |
2010年 | 621篇 |
2009年 | 790篇 |
2008年 | 972篇 |
2007年 | 932篇 |
2006年 | 899篇 |
2005年 | 799篇 |
2004年 | 721篇 |
2003年 | 679篇 |
2002年 | 624篇 |
2001年 | 445篇 |
2000年 | 395篇 |
1999年 | 402篇 |
1998年 | 359篇 |
1997年 | 307篇 |
1996年 | 289篇 |
1995年 | 296篇 |
1994年 | 279篇 |
1993年 | 275篇 |
1992年 | 234篇 |
1991年 | 213篇 |
1990年 | 213篇 |
1989年 | 179篇 |
1988年 | 159篇 |
1987年 | 136篇 |
1986年 | 115篇 |
1985年 | 120篇 |
1984年 | 169篇 |
1983年 | 103篇 |
1982年 | 108篇 |
1981年 | 102篇 |
1980年 | 89篇 |
1979年 | 72篇 |
1978年 | 55篇 |
1977年 | 35篇 |
1976年 | 32篇 |
1973年 | 17篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
111.
Stefan Jansson Eran Pichersky Roberto Bassi Beverley R. Green Masahiko Ikeuchi Anastasios Melis David J. Simpson Michael Spangfort L. Andrew Staehelin J. Philip Thornber 《Plant Molecular Biology Reporter》1992,10(3):242-253
We propose a nomenclature for the genes encoding the chlorophylla/b-binding proteins of the light-harvesting complexes of photosystem I and II. The genes encoding LHC I and LHC II polypeptides
are namedLhca1 throughLhca4 andLhcb1 throughLhcb6, respectively. The proposal follows the general format recommended by the Commision on Plant Gene Nomenclature. We also present
a table for the conversion of old gene names to the new nomenclature. 相似文献
112.
Summary The regulatory sequences leading to the ovarian and fat body expression of yolk proteins 1 and 2 (YP1 and 2) of Drosophila melanogaster have been characterised in some detail. These genes (yp1 and yp2) share many enhancer elements, and some important regulatory sequences lie within the coding regions. We have begun to investigate the cis-regulation of the gene encoding yolk protein 3 (yp3). We describe a system for P element transformation using the complete and unaltered yp3 gene rather than reporter genes and describe sequences conferring correct expression in the ovary and carcass. 相似文献
113.
P. R. Warman 《Plant and Soil》1991,134(1):115-119
A field-size experiment was initiated in 1982 on an acid, low fertility Springhill silt loam to determine the effect of five
unfertilized green manure crops (alsike clover, sweet clover, single- and double-cut red clover, and buckwheat) on subsequent
oat production and soil fertility. The field was limed in 1982 and green manures were seeded (without fertilizer) in spring,
1983 in 1400 m2 strips randomly assigned within three treatment blocks. Plant tissue samples were taken from different locations in each
plot in the fall of 1983 and all crops were incorporated. In 1984 the field was separated into an upper and lower section
and each section received three rates of NPK fertilizer (0; 30-36-36; 60-72-72 kg ha-1) spread across the previous strips. Gary oats were seeded and at harvest were divided into grain and straw. The results indicated
significant effects of field sample location, green manure type and fertilizer level on oat yields. Buckwheat significantly
reduced oat production compared to the four clovers, while the highest fertilizer rate improved oat yields compared with the
other levels of fertilizers. Elemental analysis of the green manure crops and soil fertility was compared with data of the
same crops grown in more fertile, neutral soils. 相似文献
114.
Chromosomal nonhistone high-mobility-group (HMG) proteins were purified from nuclei of maize (Zea mays L. cv. A619) endosperm and leaf tissue. Tissuespecific differences were observed in their polypeptide patterns, in in-vitro phosphorylation experiments with a casein-kinase type II, and by Western blot analysis with antisera against different HMG proteins. Gelfiltration chromatography demonstrated that maize HMG proteins occur as monomers. By measuring the capacity of the HMG proteins to bind to the 5 flanking region of a zein gene, the sensitivity of the proteins to different temperatures, salt concentrations and pH values was determined.Abbreviations EMSA
electrophoretic-mobility-shift assay
- FPLC
fast protein liquid chromatography
- HMG
high-mobility group
- kDa
kilodaltons
- PVDF
polyvinylidenedifluoride
- SDS-PAGE
sodium dodecyl sulfate-polyacrylamide gel electrophoresis
We would like to thank Mrs. E. Brutzer for excellent technical assistance. We are indebted to Mrs. M. Strecker and Dr. W. Bessler of the Institut für Immunbiologie, Freiburg, FRG, for the preparation of antisera and we gratefully acknowledge helpful discussions with Drs. T. Quayle, R. Grimm and U. Müller of this institute. This work was supported by grants from the Deutsche Forschungsgemeinschaft and the Fond der Chemischen Industrie. 相似文献
115.
C. E. Vallejos C. D. Chase 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1991,82(3):353-357
Summary The linkage relationship of 11 bean (Phaseolus vulgaris) seed proteins (including phaseolin), 9 enzyme loci, and theP locus were analyzed in backcross and F2 progenies by use of the software package Mapmaker. The progenies were obtained by crossing the breeding line XR-235-1 and the cultivar Calima. Allelic differences for seed protein loci were detected with SDS-PAGE and those for enzyme loci with starch gel electrophoresis and activity stains. The seed coat color of Calima is a red/beige mottled pattern and that of XR-235-1 is white. Segregation at theP locus was followed by recording the phenotype of the BC1S1 and F3 seed. A linkage group comprising ca. 90 cM was detected with the following gene order:Est-2 — 11 —Pha — 8 — (Spe/Spg) — 24 — P — 9 — (Spa/Spv) — 16 —Spba — 22 —Mdh-1. In addition, another linkage group was detected: (Spd/Spf/Sph) — 5 -Spca. Therefore, the seed proteins appear to be organized in clusters in the bean genome.Florida Agricultural Experiment Station, Journal Series No. R-01131 相似文献
116.
C. J. HOWARTH 《Plant, cell & environment》1991,14(8):831-841
Abstract. Climatic change as a result of the greenhouse effect is widely predicted to increase mean temperatures globally and, in turn, increase the frequency with which plants are exposed to heat shock conditions, particularly in the semi-arid tropics. The consequences of extreme high-temperature treatments on plants have been considered, particularly in relation to the synthesis of heat shock proteins (HSPs) and the capacity to acquire thermotolerance. The heat shock response is described using results obtained with seedlings of the tropical cereals, sorghum ( Sorghum bicolor ) and pearl millet ( Pennisetum glaucum ). A gradual temperature increase, as would occur in the field, is sufficient to induce thermotolerance. The synthesis of HSPs is a transient phenomenon and ceases once the stress is released. Despite the persistence of the HSPs themselves, de novo synthesis of HSPs is required for the induction of thermotolerance each time high temperatures are encountered. The effect of a repeated, diurnal heat shock was investigated and genotypic differences found in the ability to induce the heat shock response repeatedly. 相似文献
117.
High-affinity binding of3H-folate in Triton X-100 solubilized membranes of human liver displayed characteristics, e.g. apparent positive cooperativity, which are typical of specific folate binding. Ultrogel® AcA 44 chromatography of solubilized membranes saturated with3H-folate revealed a major peak of 100 kDa and a minor peak of 25 kDa. The 100 kDa peak could represent a hydrophobic membrane associated molecular form of the protein. This notion was supported by the fact that the two peaks had identical molecular weights as determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis with immunoblotting. 相似文献
118.
Mauricio M. Bustos Fatma A. Kalkan Kathryn A. VandenBosch Timothy C. Hall 《Plant molecular biology》1991,16(3):381-395
An intron-less phaseolin gene [15] was used to express phaseolin polypeptides in transgenic tobacco plants. The corresponding amounts of phaseolin immunoreactive polypeptides and mRNA were similar to those found in plants transformed with a bean genomic DNA sequence that encodes an identical -phaseolin subunit. These results justified the use of the intron-less gene for engineering of the phaseolin protein by oligonucleotide-directed mutagenesis. Each and both of the two Asn residues that serve as glycan acceptors in wild-type phaseolin were modified to prevent N-linked glycosylation. Wild-type (wti–) and mutant phaseolin glycoforms (dgly
1, dgly
2 and dgly
1,2) were localized to the protein body matrix by immunogold microscopy. Although quantitative slot-blot hybridization analysis showed similar levels of phaseolin mRNA in transgenic seed derived from all constructs, seed from the dgly
1 and dgly
2 mutations contained only 41% and 73% of that expressed from the wild-type control; even less (23%) was present in seed of plants transformed with the phaseolin dgly
1,2 gene. Additionally, the profile of 25–29 kDa processed peptides was different for each of the glycoforms, indicating that processing of the full-length phaseolin polypeptides was modified. Thus, although targeting of phaseolin to the protein body was not eliminated by removal of the glycan side-chains, decreased accumulation and stability of the full-length phaseolin protein in transgenic tobacco seed were evident.Abbreviations bp
base pair(s)
- DAF
days after flowering
- GUS
-glucuronidase
- kb
kilobase
- kDa
kilodalton 相似文献
119.
Isolation and characterization of a cDNA clone encoding the anti-viral protein from Phytolacca americana 总被引:6,自引:0,他引:6
Phytolacca anti-viral protein (PAP) was purified from Phytolacca leaves and the N-terminal was sequenced. A cDNA library was made from mRNAs isolated from Phytolacca leaves and cDNA clones for PAP were identified using oligonucleotide probes derived from the N-terminal amino acid sequence. The PAP-cDNA clone was sequenced from both directions. The predicted amino acid sequence of PAP was compared with the amino acid sequences of other ribosome-inactivating proteins. The identities of these proteins to PAP ranged from 29 to 38%, and a region was found in each with a sequence similar to the PAP sequence (AIQMVSEAARFKYI). Southern blot analysis indicates that PAP is encoded by a multi-gene family.Abbreviations MAP
Mirabilis jalapa anti-viral protein
- PAP
Phytolacca anti-viral protein
- SO6
30 kDa ribosome-inactivating protein from the seeds of Saponaria officinalis 相似文献
120.
Identification of the posttranslational modifications of bovine lens alpha B-crystallins by mass spectrometry. 总被引:1,自引:1,他引:0 下载免费PDF全文
J. B. Smith Y. Sun D. L. Smith B. Green 《Protein science : a publication of the Protein Society》1992,1(5):601-608
A combination of mass spectrometric techniques has been used to investigate the amino acid sequence and post-translational modifications of alpha B-crystallin isolated from bovine lenses by gel filtration chromatography and reversed-phase high performance liquid chromatography. Chromatographic fractions were analyzed by electrospray ionization mass spectrometry to determine the homogeneity and molecular weights of proteins in the fractions. The alpha B-crystallin primary gene product, its mono- and diphosphorylated forms, its N- and C-terminal truncated forms, as well as other lens proteins unrelated to the alpha B-crystallins were identified by their molecular weights. Detailed information about the sites of phosphorylation, as well as evidence supporting reassignment of Asn to Asp at position 80, was obtained by analyzing proteolytic digests of these proteins by fast atom bombardment mass spectrometry. Results of this investigation indicate that alpha B-crystallin is phosphorylated in vivo at Ser 45, Ser 59, and either Ser 19 or 21. From the specificity of phosphorylation of alpha-crystallins, it appears that there may be two different kinases responsible for their phosphorylation. 相似文献