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41.
Clonal origin of haematopoietic colonies in the postnatal mouse liver   总被引:3,自引:0,他引:3  
J Rossant  K M Vijh  C E Grossi  M D Cooper 《Nature》1986,319(6053):507-511
The liver of the neonatal mouse continues to show haematopoietic activity for up to 2 weeks after birth and morphological analysis has shown that this activity becomes focused in discrete haematopoietic colonies by the end of the first week postnatal. Furthermore, each colony contains cells of one haematopoietic lineage only, that is, erythroid, myeloid or pre-B-lymphoid cells. This pattern of differentiation suggests that each colony is derived from a single committed precursor cell, which, if true, would represent the first demonstration of non-mixed haematopoietic colonies in normal development and would provide a useful system for studying the factors affecting the clonal diversity of haematopoietic stem cells and their lineage-committed progeny. Here we have analysed the haematopoietic foci in the liver of neonatal mouse chimaeras, using a newly developed ubiquitous in situ cell marker system which clearly demonstrates the clonal origin of these colonies.  相似文献   
42.
This article considers policy making in practice focussing on case studies drawn from ethnographic research on prostitution in Indonesia carried out between 2012 and 2013 (this article is based on field research undertaken in Java, Indonesia, between November 2012 and 28 February 2013). Its theoretical underpinnings is that of ‘critical systemic heuristics’ which contends that policy making with respect to prostitution needs to take into account a range of factors and diverse views based on a process of ‘unfolding values’ and ‘sweeping in’ many variables before a decision is made. Applying ‘critical systemic approach’ or ‘critical heuristics’provides a means to test out the policy making ideas, as opposed to merely implementing the ideas of the powerful. The paper applies critical heuristic thinking to argue that the policy response ought to take into account the voices of those with a lived experience of poverty and prostitution, in order to protect their rights when making policy decisions.  相似文献   
43.
Type Three Secretion Systems (T3SSs) are essential virulence determinants of many Gram-negative bacteria. The T3SS is an injection device that can transfer bacterial virulence proteins directly into host cells. The apparatus is made up of a basal body that spans both bacterial membranes and an extracellular needle that possesses a channel that is thought to act as a conduit for protein secretion. Contact with a host-cell membrane triggers the insertion of a pore into the target membrane, and effectors are translocated through this pore into the host cell. To assemble a functional T3SS, specific substrates must be targeted to the apparatus in the correct order. Recently, there have been many developments in our structural and functional understanding of the proteins involved in the regulation of secretion. Here we review the current understanding of protein components of the system thought to be involved in switching between different stages of secretion.  相似文献   
44.
The challenge is (a) to balance both centralised control to preserve the global commons and (b) to involve people in policy making so that they feel culturally engaged and committed to the policy. Dictatorships and forms of World government from above to support the global commons are no more of an answer than forms of liberal democracy that do not engage people in between national elections. Passive voting does not help people in diverse democracies to engage in thinking through ‘if then scenarios’ about their social, economic and environmental future.  相似文献   
45.
R Kothary  S Clapoff  A Brown  R Campbell  A Peterson  J Rossant 《Nature》1988,335(6189):435-437
The site of integration of transgenes in the host genome can affect levels of expression and occasionally confer ectopic patterns of expression on otherwise tissue-specific genes. We describe here a line of mice in which an hsp68-lacZ transgene is expressed in unstressed developing neural tissue and where the transgene insertion has caused a mutation of a neural tissue-specific gene, dystonia musculorum (dt). This coincidence suggests that expression of the hsp68-lacZ construct may be controlled directly by cis-acting regulatory sequences that normally control the developmental expression of the dt gene. Such constructs may serve as useful tools for identifying new tissue-specific enhancers and their associated genes.  相似文献   
46.
Sustainability is not simply about changing practices but more centrally about agreeing to change practices together. To achieve such an end, groups need to improve processes for making complex decisions together. An online course was designed and tested linking students in the United States and in Australia. Students engaged in a re-enactment of deliberations based on Hasan Ozbekhan’s “Predicament of Mankind,” which was constructed originally under assignment from the founders of the Club of Rome in 1970. This re-enactment included contemporary research for examples of a set of 49 continuous critical problems of mankind, asynchronous clarification of these problems using a wiki, pair-wise construction of a systems view of problems assessed to be of highest priority by the class, narrative analysis of the structure, and creative suggestions for resolving the systems problem based on resources available today. This report comments on the strengths and challenges identified in an initial application of an approach for building collaborative and systems thinking skills through an online course in a general education curriculum. Findings are particularly meaningful for contemporary policy makers as well as online educators.  相似文献   
47.
Accumulation of amyloid fibrils in the viscera and connective tissues causes systemic amyloidosis, which is responsible for about one in a thousand deaths in developed countries. Localized amyloid can also have serious consequences; for example, cerebral amyloid angiopathy is an important cause of haemorrhagic stroke. The clinical presentations of amyloidosis are extremely diverse and the diagnosis is rarely made before significant organ damage is present. There is therefore a major unmet need for therapy that safely promotes the clearance of established amyloid deposits. Over 20 different amyloid fibril proteins are responsible for different forms of clinically significant amyloidosis and treatments that substantially reduce the abundance of the respective amyloid fibril precursor proteins can arrest amyloid accumulation. Unfortunately, control of fibril-protein production is not possible in some forms of amyloidosis and in others it is often slow and hazardous. There is no therapy that directly targets amyloid deposits for enhanced clearance. However, all amyloid deposits contain the normal, non-fibrillar plasma glycoprotein, serum amyloid P component (SAP). Here we show that administration of anti-human-SAP antibodies to mice with amyloid deposits containing human SAP triggers a potent, complement-dependent, macrophage-derived giant cell reaction that swiftly removes massive visceral amyloid deposits without adverse effects. Anti-SAP-antibody treatment is clinically feasible because circulating human SAP can be depleted in patients by the bis-d-proline compound CPHPC, thereby enabling injected anti-SAP antibodies to reach residual SAP in the amyloid deposits. The unprecedented capacity of this novel combined therapy to eliminate amyloid deposits should be applicable to all forms of systemic and local amyloidosis.  相似文献   
48.
Using DNA extracted from a finger bone found in Denisova Cave in southern Siberia, we have sequenced the genome of an archaic hominin to about 1.9-fold coverage. This individual is from a group that shares a common origin with Neanderthals. This population was not involved in the putative gene flow from Neanderthals into Eurasians; however, the data suggest that it contributed 4-6% of its genetic material to the genomes of present-day Melanesians. We designate this hominin population 'Denisovans' and suggest that it may have been widespread in Asia during the Late Pleistocene epoch. A tooth found in Denisova Cave carries a mitochondrial genome highly similar to that of the finger bone. This tooth shares no derived morphological features with Neanderthals or modern humans, further indicating that Denisovans have an evolutionary history distinct from Neanderthals and modern humans.  相似文献   
49.
This study applies critical systems thinking as a process to respond to and offer recommendations to address prostitution policy in Indonesia. The article addresses social, economic and environmental aspects of prostitution. The analysis centres on the way in which prostitution is framed by the different interest groups in Indonesia, and highlights the current crisis in policy-making praxis in Indonesia. The article develops a case for systemic policy praxis, and aims to: (1) Make a case for re-framing the issue of prostitution in the sense that it addresses the ‘capabilities’ prostituted women and children ought to have (see Sen in Development as freedom, Oxford University Press, Oxford, 1999 and Nussbaum in Women and human development: the capabilities approach, Cambridge University Press, Cambridge 2000). (2) Re-frame the policy response to prostitution to address life chances and human dignity. (3) Assert that the lack of attention to a just and fair human rights for all is due to a policy-making gap where ‘systemic intervention’ is required to restore human dignity.  相似文献   
50.
Diversity, stability and resilience of the human gut microbiota   总被引:4,自引:0,他引:4  
Trillions of microbes inhabit the human intestine, forming a complex ecological community that influences normal physiology and susceptibility to disease through its collective metabolic activities and host interactions. Understanding the factors that underlie changes in the composition and function of the gut microbiota will aid in the design of therapies that target it. This goal is formidable. The gut microbiota is immensely diverse, varies between individuals and can fluctuate over time - especially during disease and early development. Viewing the microbiota from an ecological perspective could provide insight into how to promote health by targeting this microbial community in clinical treatments.  相似文献   
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