全文获取类型
收费全文 | 1877篇 |
免费 | 154篇 |
国内免费 | 2篇 |
出版年
2023年 | 10篇 |
2022年 | 12篇 |
2021年 | 48篇 |
2020年 | 28篇 |
2019年 | 44篇 |
2018年 | 43篇 |
2017年 | 44篇 |
2016年 | 70篇 |
2015年 | 97篇 |
2014年 | 105篇 |
2013年 | 145篇 |
2012年 | 176篇 |
2011年 | 144篇 |
2010年 | 106篇 |
2009年 | 103篇 |
2008年 | 110篇 |
2007年 | 118篇 |
2006年 | 104篇 |
2005年 | 100篇 |
2004年 | 79篇 |
2003年 | 69篇 |
2002年 | 69篇 |
2001年 | 16篇 |
2000年 | 11篇 |
1999年 | 15篇 |
1998年 | 14篇 |
1997年 | 9篇 |
1996年 | 8篇 |
1995年 | 10篇 |
1994年 | 5篇 |
1993年 | 6篇 |
1991年 | 3篇 |
1990年 | 5篇 |
1989年 | 5篇 |
1988年 | 4篇 |
1987年 | 8篇 |
1986年 | 4篇 |
1985年 | 4篇 |
1984年 | 8篇 |
1983年 | 8篇 |
1980年 | 3篇 |
1979年 | 4篇 |
1978年 | 9篇 |
1977年 | 4篇 |
1976年 | 3篇 |
1975年 | 6篇 |
1973年 | 6篇 |
1972年 | 4篇 |
1969年 | 5篇 |
1966年 | 4篇 |
排序方式: 共有2033条查询结果,搜索用时 482 毫秒
71.
Andy Amphlett 《Plant Ecology & Diversity》2013,6(1):135-148
Summary Native pinewoods are fragmentary in extent and floristic integrity. In maintaining and extending these remnants, managers should recognise the diversity of potential communities and the unique mix of species in their flora. At the RSPB Abernethy Forest Reserve management aims to develop a self sustaining forest of natural character over the potential woodland area. A present-natural forest provides one model for the attributes and processes, which this forest should contain. Habitat management experiments have recently commenced investigating ways of increasing blaeberry Vaccinium myrtillus in forest areas, and increasing tree regeneration at the forest edge. The possible wider role of management intervention in pinewoods is discussed. 相似文献
72.
Heather Mchaffie Colin J. Legg Rick Worrell Neil Cowie Andy Amphlett 《Plant Ecology & Diversity》2013,6(2):209-219
Summary A substantial proportion of the Abernethy Forest Reserve has Scots pine (Pinus sylvestris) growing on the surfaces of a variety of mires. The hydrology of the mires has been affected by drainage and peat cutting but this area is unusual in having had a long period of protection from grazing by domestic stock. There are three main types of pine populations found on these mires. Woodland bog comprises predominantly bog vegetation with abundant pine seedlings due to the heavy seed rain from the surrounding woodland. Only a few very small trees survive, which are stunted, heavily diseased and have very low seed production. Wooded bog also comprises predominately bog vegetation but there are scattered mature trees of a moderate height with an open canopy. The trees are fertile and can form uneven aged stands with regeneration. Bog woodland is a predominantly woodland vegetation with tall, dense tree cover on deep peat. The trees are well grown with a dense canopy. A few remnants of bog vegetation remain in the ground flora although most have been replaced by woodland bryophytes and shrubs. Each of these three types is described and their development is discussed. 相似文献
73.
Kamila Wojciechowicz Karl Gledhill Carrie A. Ambler Craig B. Manning Colin A. B. Jahoda 《PloS one》2013,8(3)
The laboratory mouse is a key animal model for studies of adipose biology, metabolism and disease, yet the developmental changes that occur in tissues and cells that become the adipose layer in mouse skin have received little attention. Moreover, the terminology around this adipose body is often confusing, as frequently no distinction is made between adipose tissue within the skin, and so called subcutaneous fat. Here adipocyte development in mouse dorsal skin was investigated from before birth to the end of the first hair follicle growth cycle. Using Oil Red O staining, immunohistochemistry, quantitative RT-PCR and TUNEL staining we confirmed previous observations of a close spatio-temporal link between hair follicle development and the process of adipogenesis. However, unlike previous studies, we observed that the skin adipose layer was created from cells within the lower dermis. By day 16 of embryonic development (e16) the lower dermis was demarcated from the upper dermal layer, and commitment to adipogenesis in the lower dermis was signalled by expression of FABP4, a marker of adipocyte differentiation. In mature mice the skin adipose layer is separated from underlying subcutaneous adipose tissue by the panniculus carnosus. We observed that the skin adipose tissue did not combine or intermix with subcutaneous adipose tissue at any developmental time point. By transplanting skin isolated from e14.5 mice (prior to the start of adipogenesis), under the kidney capsule of adult mice, we showed that skin adipose tissue develops independently and without influence from subcutaneous depots. This study has reinforced the developmental link between hair follicles and skin adipocyte biology. We argue that because skin adipocytes develop from cells within the dermis and independently from subcutaneous adipose tissue, that it is accurately termed dermal adipose tissue and that, in laboratory mice at least, it represents a separate adipose depot. 相似文献
74.
75.
Mitchell E. Nuhn Manfred Binder Andy F.S. Taylor Roy E. Halling David S. Hibbett 《Fungal biology》2013,117(7-8):479-511
The generic and sub-generic relationships in the Boletineae (Boletales) were studied using nuclear large subunit (nuc-lsu), translation elongation factor 1-alpha (tef1), and DNA directed RNA polymerase largest subunit (RPB1). The Boletineae, with the exclusion of Hydnomerulius pinastri, was strongly supported and the status of the families Boletaceae and Paxillaceae is discussed. Members of the genus Boletus are found throughout the phylogeny, with the majority not closely related to the type species, Boletus edulis. Many of the traditional, morphologically defined genera are not supported as monophyletic and additional sampling and taxonomic revisions are needed. The majority of the Boletineae are confirmed or putatively ectomycorrhizal (ECM), but two putatively mycoparasitic lineages (one lineage of Buchwaldoboletus lignicola and Chalciporus piperatus and the second Pseudoboletus parasiticus) are strongly supported. 相似文献
76.
77.
78.
79.
Mark Pennington Aleksandra Gentry-Maharaj Chloe Karpinskyj Alec Miners Julie Taylor Ranjit Manchanda Rema Iyer Michelle Griffin Andy Ryan Ian Jacobs Usha Menon Rosa Legood 《PloS one》2016,11(11)
BackgroundThere is limited evidence on the costs of Endometrial Cancer (EC) by stage of disease. We estimated the long-term secondary care costs of EC according to stage at diagnosis in an English population-based cohort.MethodsWomen participating in UKCTOCS and diagnosed with EC following enrolment (2001–2005) and prior to 31st Dec 2009 were identified to have EC through multiple sources. Survival was calculated through data linkage to death registry. Costs estimates were derived from hospital records accessed from Hospital Episode Statistics (HES) with additional patient level covariates derived from case notes and patient questionnaires. Missing and censored data was imputed using Multiple Imputation. Regression analysis of cost and survival was undertaken.Results491 of 641 women with EC were included. Five year total costs were strongly dependent on stage, ranging from £9,475 (diagnosis at stage IA/IB) to £26,080 (diagnosis at stage III). Stage, grade and BMI were the strongest predictors of costs. The majority of costs for stage I/II EC were incurred in the first six months after diagnosis while for stage III / IV considerable costs accrued after the first six months.ConclusionsIn addition to survival advantages, there are significant cost savings if patients with EC are detected earlier. 相似文献
80.
Austin Chin Chwan Ng Dona Adikari David Yuan Jerrett K. Lau Andy Sze Chiang Yong Vincent Chow Leonard Kritharides 《PloS one》2016,11(3)