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981.
982.
983.
This article describes the first results from the recent revision to The ONS classification of local and health authorities of Great Britain to allow for boundary changes. For each local and health authority of Great Britain as at April 1999 it presents 'most similar' authorities as measured by a selection of 37 socioeconomic and demographic variables from the 1991 Census. These results will assist local and health authorities in identifying other appropriate authorities for comparative studies. A second article, to be published in Population Trends 99, will present the results of the analysis to identify groups of authorities in a hierarchy of new Clusters, Groups and Families for the revised classification. 相似文献
984.
Hyaluronan synthases: fascinating glycosyltransferases from vertebrates, bacterial pathogens, and algal viruses 总被引:14,自引:0,他引:14
DeAngelis PL 《Cellular and molecular life sciences : CMLS》1999,56(7-8):670-682
Hyaluronan (or hyaluronic acid or hyaluronate; HA) is a polysaccharide found in the extracellular matrix of vertebrate tissues and in the surface coating of certain Streptococcus and Pasteurella bacterial pathogens. At least one algal virus directs its host to produce HA on the cell surface early in infection. HA synthases (HASs) are the enzymes that polymerize HA using uridine diphospho-sugar precursors. In all known cases, HA is secreted out of the cell; therefore, HASs are normally found in the outer membranes of the organism. In the last 6 years, the HASs have been molecularly cloned from all the above sources. They were the first class of glycosyltransferases identified in which a single polypeptide species catalyzes the transfer of two different monosaccharides; this finding is in contrast to the usual 'single enzyme, single sugar' dogma of glycobiology. There appear to be two distinct classes of HASs based on differences in amino acid sequence, topology in the membrane, and reaction mechanism. This review discusses the current state of knowledge surrounding the molecular details of HA biosynthesis and summarizes the possible evolutionary history of the HASs. 相似文献
985.
Integrin antagonists 总被引:4,自引:0,他引:4
Integrins are a family of cell surface glycoproteins that mediate numerous cell-cell and cell-matrix interactions and are
involved in biological processes such as tissue morphogenesis, leukocyte recirculation and migration, wound healing, blood
clotting and immune response. Aberrant cell adhesion has been implicated in the pathogenesis of several diseases, including
a number of inflammatory disorders such as rheumatoid arthritis, inflammatory bowel disease and asthma, as well as cancer
and coronary heart disease. As such integrins are seen as excellent targets for the development of therapeutic agents. This
report begins with an examination of the structure of integrin molecules and their ligands and then goes on to review the
current state of development of antiintegrin antagonists.
Received 13 April 1999; received after revision 28 May 1999; accepted 28 May 1999 相似文献
986.
The one-to-four rule and paralogues of sex-determining genes 总被引:5,自引:0,他引:5
S. Ohno 《Cellular and molecular life sciences : CMLS》1999,55(6-7):824-830
987.
Alberti S 《Cellular and molecular life sciences : CMLS》1999,56(1-2):85-93
A better definition of the structural and thermodynamic determinants of the interaction of nucleic acids with proteins is shedding light on the origin of the genetic code, protein synthesis, and nucleic acid replication. This is also allowing to show a consistent biochemical framework for the appearance of these fundamental synthetic mechanisms. This article reviews recent significant developments in the field, and discusses an integrated model for a biochemically plausible evolution of these fundamental mechanisms of synthesis. This model is based on sequence-specific interactions between abiotically synthesized polynucleotides and polypeptides, and can account for a coordinate evolution of the genetic code, protein synthesis, and nucleic acid replication in living cells. 相似文献
988.
Amin AR Attur MG Pillinger M Abramson SB 《Cellular and molecular life sciences : CMLS》1999,56(3-4):305-312
Recent studies have suggested that aspirin and aspirin-like compounds have a variety of actions in addition to their well-studied
ability to inhibit cyclooxygenases. These actions include inhibition of the uncoupling of oxidative phosphorylation, decreases
in adenosine triphosphate stores, increases in extracellular adenosine, downregulation of the expression and activity of inducible
nitric oxide synthetase, inhibition and/or stimulation of various mitogen-activated protein kinase activities and inhibition
of nuclear factor binding κB site (NF-κB) activation. Moreover, aspirin-like compounds have recently been shown to have previously
unappreciated clinical and biological effects, some apparently independent of cyclooxygenase. In this review we discuss the
various mechanisms of action of aspirin-like compounds and their relevance to clinical disease and therapy.
Received 1 February 1999; received after revision 1 April 1999; accepted 7 May 1999 相似文献
989.
A population of ventral neural tube cells has recently been shown to migrate out of the hind brain neural tube via the vagus
nerve and contribute to the developing gastrointestinal tract. Since liver is also innervated by the vagus nerve, we sought
to determine if these cells also migrate into the liver. Ventral neural tube cells in the caudal hindbrain of chick embryos
were tagged with a replication-deficient retroviral vector containing the LacZ gene on embryonic day 2. Embryos were processed
for detection of labeled cells on embryonic day 5 and 11. Labeled cells were seen in the liver on both days and identified
as hepatocytes. Previously, it was believed that all hepatocytes develop from the gut endoderm. Results of the present study
show an additional source for the formation of liver cells.
Received 25 August 1998; received after revision 5 November 1998; accepted 5 November 1998 相似文献
990.
T. P. O’Connor 《Cellular and molecular life sciences : CMLS》1999,55(11):1358-1364
Neurons must often extend axons over fairly long distances, making multiple changes in their trajectory of growth before
arriving at their final target. It has become clear that as growth cones navigate these complex projections, they typically
extend toward a number of intermediate targets before they contact their final target. Recent work from a variety of systems
has identified intermediate targets that seem to play similar roles in vertebrate and invertebrate nervous system development.
From these examples it appears that a general model of axon guidance can be proposed whereby neurons are guided to their targets
segmentally. Within each segment, an intermediate target appears to be the primary target for growth cone recognition and
thus the completion of the journey to the final target is determined by a series of successful segmental pathfinding decisions. 相似文献