全文获取类型
收费全文 | 1232篇 |
免费 | 55篇 |
国内免费 | 68篇 |
出版年
2023年 | 4篇 |
2022年 | 11篇 |
2021年 | 16篇 |
2020年 | 13篇 |
2019年 | 18篇 |
2018年 | 19篇 |
2017年 | 19篇 |
2016年 | 26篇 |
2015年 | 30篇 |
2014年 | 35篇 |
2013年 | 87篇 |
2012年 | 27篇 |
2011年 | 52篇 |
2010年 | 34篇 |
2009年 | 53篇 |
2008年 | 53篇 |
2007年 | 64篇 |
2006年 | 56篇 |
2005年 | 57篇 |
2004年 | 52篇 |
2003年 | 69篇 |
2002年 | 33篇 |
2001年 | 40篇 |
2000年 | 26篇 |
1999年 | 32篇 |
1998年 | 30篇 |
1997年 | 39篇 |
1996年 | 34篇 |
1995年 | 49篇 |
1994年 | 46篇 |
1993年 | 21篇 |
1992年 | 23篇 |
1991年 | 19篇 |
1990年 | 13篇 |
1989年 | 11篇 |
1988年 | 23篇 |
1987年 | 15篇 |
1986年 | 14篇 |
1985年 | 20篇 |
1984年 | 12篇 |
1983年 | 10篇 |
1982年 | 16篇 |
1981年 | 8篇 |
1980年 | 12篇 |
1979年 | 3篇 |
1978年 | 7篇 |
1977年 | 3篇 |
1976年 | 1篇 |
排序方式: 共有1355条查询结果,搜索用时 15 毫秒
281.
Ron R. van Eijsden Clara L. Díaz B. Sylvia de Pater Jan W. Kijne 《Plant molecular biology》1995,29(3):431-439
Legume lectin stimulates infection of roots in the symbiosis between leguminous plants and bacteria of the genus Rhizobium. Introduction of the Pisum sativum lectin gene (psl) into white clover hairy roots enables heterologous infection and nodulation by the pea symbiont R. leguminosarum biovar viciae (R.l. viciae). Legume lectins contain a specific sugar-binding site. Here, we show that inoculation of white clover hairy roots co-transformed with a psl mutant encoding a non-sugar-binding lectin (PSL N125D) with R.l. viciae yielded only background pseudo-nodule formation, in contrast to the situation after transformation with wild type psl or with a psl mutant encoding sugar-binding PSL (PSL A126V). For every construct tested, nodulation by the homologous symbiont R.l. trifolii was normal. These results strongly suggest that (1) sugar-binding activity of PSL is necessary for infection of white clover hairy roots by R.l. viciae, and (2) the rhizobial ligand of host lectin is a sugar residue rather than a lipid. 相似文献
282.
The seed lectins of black locust (robinia pseudoacacia) are encoded by two genes which differ from the bark lectin genes 总被引:2,自引:0,他引:2
Els J. M. Van Damme Annick Barre Pierre Rougé Fred Van Leuven Willy J. Peumans 《Plant molecular biology》1995,29(6):1197-1210
Two lectins were isolated from Robinia pseudoacacia (black locust) seeds using affinity chromatography on fetuin-agarose, and ion exchange chromatography on a Neobar CS column. The first lectin, R. pseudoacacia seed agglutinin I, referred to as RPsAI, is a homotetramer of four 34 kDa subunits whereas the second lectin, referred to as RPsAII, is composed of four 29 kDa polypeptides. cDNA clones encoding the polypeptides of RPsAI and RPsAII were isolated and their sequences were determined. Both polypeptides are translated from mRNAs of ca. 1.2 kb encoding a precursor carrying a signal peptide. Alignment of the deduced amino acid sequences of the different clones indicates that the 34 and 29 kDa seed lectin polypeptides show 95% sequence identity. In spite of this striking homology, the 29 kDa polypeptide has only one putative glycosylation site whereas the 34 kDa subunit has four of these sites. Carbohydrate analysis revealed that the 34 kDa possesses three carbohydrate chains whereas the 29 kDa polypeptide is only partially glycosylated at one site. A comparison of the deduced amino acid sequences of the two seed and three bark lectin polypeptides demonstrated unambiguously that they are encoded by different genes. This implies that five different genes are involved in the control of the expression of the lectins in black locust.Abbreviations LECRPAs
cDNA clone encoding Robinia pseudoacacia seed lectin
- LoLI
Lathyrus ochrus isolectin I
- PsA
Pisum sativum agglutinin
- RPbAI
Robinia pseudoacacia bark agglutinin I
- RPbAII
Robinia pseudoacacia bark agglutinin II
- RPsAI
Robinia pseudoacacia seed agglutinin I
- RPsAII
Robinia pseudoacacia seed agglutinin II 相似文献
283.
猪精子凝集素在精卵结合中的作用机制 总被引:3,自引:0,他引:3
猪精子凝集素(BSL)位于精子头部,既与精子蛋白结合,亦与透明带糖蛋白ZP3结合。并且BSL自身分子间亦会聚合。与ZP3结合的片段亦结合于岩藻素-Sepharose亲和柱,但不与胎球蛋白-Sepharose柱结合。该片段具有较强的抑制精卵结合的活性。BSL经NBS修饰后,血凝活力大大下降,同时推动与精子结合的活性,但不影响它与ZP3的结合。修饰后的BSL亦显著抑制精卵结合。表明BSL以两个不同的部 相似文献
284.
经肼解、Bio-Gel P-2柱层析、NaB^3H4和NaBH4还原,制备各种来源的、氚标记在还原末端的、还原末端为N-乙酰氨基葡萄糖醇的混合寡糖,经Bio-Gel P-4凝胶柱分离,以及用糖苷酶酶解,制备了各种不同类型的氚标记的寡糖。这些寡糖在固定化的PCL-Sepharose柱上亲和层析,根据各种类型寡糖在PCL-Sepharose柱上的层析行为,确定红花菜豆(矮生红花变种)凝集素(PCL)的 相似文献
285.
纯化的红花菜豆凝集素经肼解,Bio-GelP-2柱分离,得到的寡糖部份用硼氢化钠还原,再红Bio-Gel P-4柱层析,获得两条寡糖链。通过甲醇解,乙酰化反应,最后制成三甲基硅醚衍生物。气相色谱分析表面两个寡糖的组成为;Man8Xy1GlcNAc2和Man6XylGlcNa2Fuc。 相似文献
286.
A detailed study was made of the bark lectins of the legume tree Maackia amurensis using a combination of protein purification
and cDNA cloning. The lectins, which are the most abundant bark proteins, are a complex mixture of isoforms composed of two
types of subunits of 32 and 37 kDa, respectively. Isolation and characterization of the homotetrameric isoforms indicated
that the 32 kDa subunit exhibits a 100-fold stronger haemagglutinating activity than the 37 kDa subunit. Molecular cloning
confirmed that the two lectin subunits are encoded by different genes. The 32 kDa subunit is apparently encoded by a single
gene, whereas two highly homologous genes encode the 37 kDa subunit. A comparison of the deduced amino acid sequences of the
bark lectin cDNAs and the previously described cDNA encoding the seed haemagglutinin demonstrated that they are encoded by
different genes. Abbreviations: LECMAHb, cDNA clone encoding Maackia amurensis bark haemagglutinin; LECMALb, cDNA clone encoding
Maackia amurensis bark leucoagglutinin; MALb, Maackia amurensis bark leucoagglutinin; MAHb, Maackia amurensis bark haemagglutinin
This revised version was published online in November 2006 with corrections to the Cover Date. 相似文献
287.
Cultured chondrocytes derived from the caudal and cephalic ends of embryonic chick sterna have been compared with each other
and with whole sternum, by using a panel of 21 lectins to probe the distribution of oligosaccharides in glycoconjugates of
cells and matrix at various times of culture or development. On culture in collagen gels, the cells changed their morphology
with time, degrading glycan in the surrounding culture medium and depositing new matrix, the glycan content of which reflected
the site of origin of the cells, indicating that the glycan phenotype of both cells and matrix (‘glycotype’) was predetermined
and persistent. Sterna of embryonic chicks showed unexpected complexity in their distribution pattern of glycan, containing
at least six distinct regions. Major regional temporal differences were evident among saccharides terminating in α-N-acetyl
galactosamine and β-galactose, while changes in glycans terminating in fucose, sialic acid and α-mannose were somewhat less
marked. Subsets of complex N-glycans changed little.
This revised version was published online in November 2006 with corrections to the Cover Date. 相似文献
288.
Els C. M. Brinkman-Van Der Linden Esther C. R. Van Ommen Willem Van Dijk 《Glycoconjugate journal》1996,13(1):27-31
The occurrence of differences in acute-phase response, with respect to concentration and glycosylation of 1-acid glycoprotein (AGP) was studied in the sera of patients surviving or not from septic shock. Crossed affino-immunoelectrophoresis was used with concanavalin A andAleuria aurantia lectin for the detection of the degree of branching and fucosylation, respectively, and the monoclonal CSLEX-1 for the detection of sialyl Lewisx (SLeX) groups on AGP. Septic shock apparently induced an acute-phase response as indicated by the increased serum levels and changed glycosylation of AGP. In the survivor group a transient increase in diantennary glycan content was accompanied by a gradually increasing fucosylation and SLeX expression, comparable to those observed in the early phase of an acute-inflammatory response. Remarkably, in the non-survivor group a modest increase in diantennary glycan content was accompanied by a strong elevation of the fucosylation of AGP and the expression of SLeX groups on AGP, typical for the late phase of an acute-phase response. Our results suggest that these changes in glycosylation of AGP can have a prognostic value for the outcome of septic shock.Abbreviations AAL
Aleuria aurantia lectin
- AGP
1-acid glycoprotein
- CAIE
crossed affinoimmunoelectrophoresis
- Con A
Concanavalin A
- HSPC
human serum protein calibrator
- IL-1
interleukin 1
- IL-6
interleukin 6
- LIF
leukaemia inhibitory factor
- LPS
lipopolysaccharide
- SLeX
sialyl Lewisx
- TNF
tumour necrosis factor 相似文献
289.
Chatchadaporn Krungkasem Kyoko Ueda Hirofumi Tachibana Sanetaka Shirahata 《Cytotechnology》1997,25(1-3):145-154
We found that when the hybridoma cell line HB4C5 was stimulated with wheat germ agglutinin (WGA), loss of production of the
original λ light chain occurred, followed by production of new light chain, which mirrored the reaction when stimulated with
concanavalin A (ConA). We previously reported that the RAG genes are expressed not only in HB4C5 and its ConA-treated variant
subclones, but also in the in the parental Namalwa cells, which are known to be in the plasma state. However, the new λ light
chains were expressed only in the HB4C5 cells and not in the parental Namalwa cells. Here we found that the RAG genes are
expressed in HB4C5 cells after continuous stimulation with WGA. To further investigate the mechanism of this loss of original
λ light chain production by stimulation with lectins in HB4C5 cells, which leads to a sIg-negative subpopulation, we analyzed
the differences between HB4C5 and Namalwa cells. In this present study, we found that a 70 kDa phosphorylated protein in HB4C5
cells became undetectable after stimulation with lectins (WGA and ConA), and was not detected in Namalwa cells before or after
lectin stimulation. It has been believed that the RAG genes and loss of original λ light chain production are required to
induce expression of a new λ light chain in the HB4C5 cells. We suggested that the phosphorylated 70 kDa protein in HB4C5
cells play important roles in regulating the production of new λ light chains which is induced by lectins.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
290.
Lena Suzuki Jeffrey P. Woessner Hidenobu Uchida† Haruko Kuroiwa Yasuhito Yuasa Sabine Waffenschmidt Ursula W. Goodenough Tsuneyoshi Kuroiwa 《Journal of phycology》2000,36(3):571-583
The cell wall of Chlamydomonas reinhardtii zygotes, which forms rapidly after the fusion of wall-free gametes, provides a tractable system for studying the properties and assembly of hydroxyproline-rich glycoproteins, the major proteinaceous components of green algal and plant cell walls. We report the cloning of the zsp2 gene and the analysis of its ZSP-2 product, a 58.9 kDa polypeptide that is synthesized exclusively by zygotes. The protein contains two (SP)x repeats, establishing it as a member of the cell wall hydroxyproline-rich glycoproteins family. It also contains a 4-fold iteration of an amino acid sequence centered around cysteine residues, a configuration found in both plant and animal lectins. Furthermore, we report four observations on pellicle composition and production. First, cell-free preparations of the pellicle matrix are rich in hydroxyproline, arabinose, and galactose and contain bundles of very long fibrils. Second, glutathione blocks pellicle formation and results in the accumulation of long fibrils in the growth medium. Third, antibody to ZSP-2 also blocks pellicle formation. Fourth, ZSP-2 immunolocalizes to the boundary between the outer layers of the wall proper and the pellicle matrix. These observations are consistent with the possibility that the Cys-rich (glutathione-sensitive) lectin-like domains of ZSP-2 may bind to sugar residues on the long fibrils and anchor them to the cell wall, thereby initiating and maintaining pellicle formation. 相似文献