全文获取类型
收费全文 | 504篇 |
免费 | 22篇 |
国内免费 | 1篇 |
出版年
2014年 | 5篇 |
2013年 | 10篇 |
2012年 | 7篇 |
2011年 | 15篇 |
2010年 | 37篇 |
2009年 | 24篇 |
2008年 | 19篇 |
2007年 | 28篇 |
2006年 | 22篇 |
2005年 | 13篇 |
2004年 | 5篇 |
2002年 | 5篇 |
1999年 | 6篇 |
1998年 | 7篇 |
1997年 | 14篇 |
1996年 | 7篇 |
1995年 | 7篇 |
1993年 | 9篇 |
1992年 | 7篇 |
1991年 | 10篇 |
1990年 | 4篇 |
1989年 | 10篇 |
1987年 | 7篇 |
1985年 | 8篇 |
1984年 | 4篇 |
1983年 | 4篇 |
1982年 | 5篇 |
1980年 | 8篇 |
1978年 | 5篇 |
1977年 | 6篇 |
1976年 | 8篇 |
1975年 | 4篇 |
1974年 | 8篇 |
1972年 | 14篇 |
1971年 | 9篇 |
1968年 | 6篇 |
1966年 | 4篇 |
1959年 | 9篇 |
1958年 | 6篇 |
1957年 | 7篇 |
1956年 | 9篇 |
1955年 | 8篇 |
1954年 | 8篇 |
1953年 | 10篇 |
1952年 | 6篇 |
1951年 | 4篇 |
1950年 | 9篇 |
1949年 | 4篇 |
1948年 | 6篇 |
1941年 | 5篇 |
排序方式: 共有527条查询结果,搜索用时 265 毫秒
51.
In 1995, slug damage and numbers of slugs were estimated intwo grass strips and adjacent rape fields. Investigations beganas soon as rape seedlings emerged and lasted for five weeks.Slug damage to rape plants 1 m from the grass strips was significantlyhigher than at greater distances from the strips. Derocerasreticulatum was the most abundant slug species recorded in bothgrass strips and adjacent rape fields. Arion lusitanicus andArion fasciatus were much less abundant than D. reticulatum.In one field, D. reticulatum declined steadily with increasingdistance from the grass strips and therefore appeared to havecaused the majority of severe damage to rape plants close tothe strips. This finding was surprising because until now severeslug damage in oilseed rape beside semi-natural habitats hasbeen observed only where A. lusitanicus was abundant. (Received 12 November 1997; accepted 26 January 1998) 相似文献
52.
53.
R. L. CONNER J. R. LANDREY J. R. LANDREY C. H. BURNS FRANK B. MALLORY 《The Journal of eukaryotic microbiology》1968,15(3):600-605
SYNOPSIS. Tetrahymena pyriformis synthesizes tetrahymanol and “diplopterol” from acetate, mevalonate or squalene. The formation of these pentacyclic triterpenoid alcohols is inhibited by the addition of cholesterol to the culture fluid of the ciliates. Cholesterol also inhibits the biosynthesis of squalene from acetate or mevalonic acid. The synthesis of other terpene derivatives from acetate and mevalonate continues in the presence of cholesterol, thus suggesting that a major block occurs after “isoprene” formation and before squalene formation. Further, inhibition of squalene conversion to the pentacyclic alcohols by cholesterol has been established. 相似文献
54.
55.
56.
57.
S. A. FRANK 《Journal of evolutionary biology》2009,22(8):1563-1585
We typically observe large‐scale outcomes that arise from the interactions of many hidden, small‐scale processes. Examples include age of disease onset, rates of amino acid substitutions and composition of ecological communities. The macroscopic patterns in each problem often vary around a characteristic shape that can be generated by neutral processes. A neutral generative model assumes that each microscopic process follows unbiased or random stochastic fluctuations: random connections of network nodes; amino acid substitutions with no effect on fitness; species that arise or disappear from communities randomly. These neutral generative models often match common patterns of nature. In this paper, I present the theoretical background by which we can understand why these neutral generative models are so successful. I show where the classic patterns come from, such as the Poisson pattern, the normal or Gaussian pattern and many others. Each classic pattern was often discovered by a simple neutral generative model. The neutral patterns share a special characteristic: they describe the patterns of nature that follow from simple constraints on information. For example, any aggregation of processes that preserves information only about the mean and variance attracts to the Gaussian pattern; any aggregation that preserves information only about the mean attracts to the exponential pattern; any aggregation that preserves information only about the geometric mean attracts to the power law pattern. I present a simple and consistent informational framework of the common patterns of nature based on the method of maximum entropy. This framework shows that each neutral generative model is a special case that helps to discover a particular set of informational constraints; those informational constraints define a much wider domain of non‐neutral generative processes that attract to the same neutral pattern. 相似文献
58.
59.
60.
This article will contextualize ethnographic and clinicalfeatures that distinguish one particular alternativehealing method (Self-Acceptance Training) frommainstreampsychotherapeutic procedures. Factors common to manypsychotherapies are listed and a series of contrasts andcomparisons made by examining definitions of: (1) presentingproblems, (2) inciting events, (3) phasic development, (4)taxonomic classifications, (5) therapeutic interventions,and (6) prognostic formulations. The alternative method oftreatment described in a companion publication(SAT) is used to makesome specific comparisons (Zatzick and Johnson 1997).Baschs (1980) concise recording of a dynamic therapy isborrowed for purposes of a comparative hypothetical treatmentof his patient through a Self-Acceptance Training session.Some directions for future work are suggested. 相似文献