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991.
Huet J Wyckmans J Wintjens R Boussard P Raussens V Vandenbussche G Ruysschaert JM Azarkan M Looze Y 《Cellular and molecular life sciences : CMLS》2006,63(24):3042-3054
Two chitinases, able to use tetra-N-acetylglucosamine, chitin and chitosan as substrates, were characterized after purification from Carica papaya latex. The complete amino acid sequence of the major form and about 40% of the minor one were determined through proteolytic
digestions and mass spectroscopy analysis. Sequencing demonstrated that both papaya chitinases are members of the family 19
of glycosyl hydrolases (GH19). Based on the known 3-D structures of other members of family GH19, it was expected that papaya
chitinases would adopt all-alpha structures. However, circular dichroism and infrared spectroscopy indicated, for the papaya
chitinases, a content of 15–20% of extended structures besides the expected 40% of alpha helices. Since the fully sequenced
papaya chitinase contains a large number of proline residues the possibility that papaya chitinase contains polyproline II
stretches was examined in the context of their resistance against proteolytic degradation.
Received 11 July 2006; received after revision 13 October 2006; accepted 25 October 2006 相似文献
992.
The use of anti-5-methylcytosine antibodies in affinity columns allowed the identification of methylated sequences in the
genome of Drosophila melanogaster adults. In view of the presence of transposable elements amongst the identified sequences, it has been suggested that DNA
methylation is involved in transposon control in the fly genome. On the contrary, a reanalysis of these data furnishes several
intriguing elements that could raise new questions about the role that DNA methylation plays in the fly genome. The aim of
the present paper is to discuss some features that emerge from the analysis of the identified methylated sequences.
Received 26 January 2006; received after revision 8 May 2006; accepted 2 June 2006 相似文献
993.
Myelin basic protein: a multifunctional protein 总被引:1,自引:1,他引:0
Boggs JM 《Cellular and molecular life sciences : CMLS》2006,63(17):1945-1961
Myelin basic protein (MBP), the second most abundant protein in central nervous system myelin, is responsible for adhesion
of the cytosolic surfaces of multilayered compact myelin. A member of the ‘intrinsically disordered’ or conformationally adaptable
protein family, it also appears to have several other functions. It can interact with a number of polyanionic proteins including
actin, tubulin, Ca2+-calmodulin, and clathrin, and negatively charged lipids, and acquires structure on binding to them. It may act as a membrane
actin-binding protein, which might allow it to participate in transmission of extracellular signals to the cytoskeleton in
oligodendrocytes and tight junctions in myelin. Some size isoforms of MBP are transported into the nucleus and thus they may
also bind polynucleotides. Extracellular signals received by myelin or cultured oligodendrocytes cause changes in phosphorylation
of MBP, suggesting that MBP is also involved in signaling. Further study of this very abundant protein will reveal how it
is utilized by the oligodendrocyte and myelin for different purposes.
Received 2 March 2006; received after revision 12 April 2006; accepted 16 May 2006 相似文献
994.
Phytanic acid is a branched-chain fatty acid that accumulates in a variety of metabolic disorders. High levels of phytanic
acid found in patients can exceed the millimolar range and lead to severe symptoms. Degradation of phytanic acid takes place
by α-oxidation inside the peroxisome. A deficiency of its breakdown, leading to elevated levels, can result from either a
general peroxisomal dysfunction or from a defect in one of the enzymes involved in α-oxidation. Research on Refsum disease,
belonging to the latter group of disorders and characterized by a deficiency of the first enzyme of α-oxidation, has extended
our knowledge of phytanic acid metabolism and pathology of the disease greatly over the past few decades. This review will
centre on this research on phytanic acid: its origin, the mechanism by which its α-oxidation takes place, its role in human
disease and the way it is produced from phytol.
Received 4 October 2005; received after revision 24 February 2006; accepted 26 April 2006 相似文献
995.
Selenium is an essential trace element. In cattle, selenium deficiency causes dysfunction of various organs, including skeletal
and cardiac muscles. In humans as well, lack of selenium is associated with many disorders, but despite accumulation of clinical
reports, muscle diseases are not generally considered on the list. The goal of this review is to establish the connection
between clinical observations and the most recent advances obtained in selenium biology. Recent results about a possible role
of selenium-containing proteins in muscle formation and repair have been collected. Selenoprotein N is the first selenoprotein
linked to genetic disorders consisting of different forms of congenital muscular dystrophies. Understanding the muscle disorders
associated with selenium deficiency or selenoprotein N dysfunction is an essential step in defining the causes of the disease
and obtaining a better comprehension of the mechanisms involved in muscle formation and maintenance.
Received 13 July 2005; received after revision 9 September 2005; accepted 4 October 2005 相似文献
996.
Memories become stabilized through a time-dependent process that requires gene expression and is commonly known as consolidation. During this time, memories are labile and can be disrupted by a number of interfering events, including electroconvulsive shock, trauma and other learning or the transient effect of drugs such as protein synthesis inhibitors. Once consolidated, memories are insensitive to these disruptions. However, they can again become fragile if recalled or reactivated. Reactivation creates another time-dependent process, known as reconsolidation, during which the memory is restabilized. Here we discuss some of the questions currently debated in the field of memory consolidation and reconsolidation, the molecular and anatomical requirements for both processes and, finally, their functional relationship. 相似文献
997.
998.
Galectin-7 总被引:4,自引:0,他引:4
Galectins are a family of animal lectins with an affinity for β-galactosides. They are differentially expressed by various
tissues and appear to be functionally multivalent, exerting a wide range of biological activities both during development
and in adult tissue. Galectin-7, a member of this family, contributes to different events associated with the differentiation
and development of pluristratified epithelia. It is also associated with epithelial cell migration, which plays a crucial
role in the re-epithelialization process of corneal or epidermal wounds. In addition, recent evidence indicates that galectin-7,
designated as the product of the p53-induced gene 1 (PIG1), is a regulator of apoptosis through JNK activation and mitochondrial
cytochrome c release. Defects in apoptosis constitute one of the major hallmarks of human cancers, and galectin-7 can act
as either a positive or a negative regulatory factor in tumour development, depending on the histological type of the tumour.
Received 30 October 2005; received after revision 15 November 2005; accepted 25 November 2005 相似文献
999.
Amundadottir LT Sulem P Gudmundsson J Helgason A Baker A Agnarsson BA Sigurdsson A Benediktsdottir KR Cazier JB Sainz J Jakobsdottir M Kostic J Magnusdottir DN Ghosh S Agnarsson K Birgisdottir B Le Roux L Olafsdottir A Blondal T Andresdottir M Gretarsdottir OS Bergthorsson JT Gudbjartsson D Gylfason A Thorleifsson G Manolescu A Kristjansson K Geirsson G Isaksson H Douglas J Johansson JE Bälter K Wiklund F Montie JE Yu X Suarez BK Ober C Cooney KA Gronberg H Catalona WJ Einarsson GV 《Nature genetics》2006,38(6):652-658
With the increasing incidence of prostate cancer, identifying common genetic variants that confer risk of the disease is important. Here we report such a variant on chromosome 8q24, a region initially identified through a study of Icelandic families. Allele -8 of the microsatellite DG8S737 was associated with prostate cancer in three case-control series of European ancestry from Iceland, Sweden and the US. The estimated odds ratio (OR) of the allele is 1.62 (P = 2.7 x 10(-11)). About 19% of affected men and 13% of the general population carry at least one copy, yielding a population attributable risk (PAR) of approximately 8%. The association was also replicated in an African American case-control group with a similar OR, in which 41% of affected individuals and 30% of the population are carriers. This leads to a greater estimated PAR (16%) that may contribute to higher incidence of prostate cancer in African American men than in men of European ancestry. 相似文献
1000.