全文获取类型
收费全文 | 114412篇 |
免费 | 22754篇 |
国内免费 | 51篇 |
出版年
2023年 | 261篇 |
2022年 | 751篇 |
2021年 | 1994篇 |
2020年 | 3013篇 |
2019年 | 4730篇 |
2018年 | 5183篇 |
2017年 | 5228篇 |
2016年 | 6183篇 |
2015年 | 7633篇 |
2014年 | 7738篇 |
2013年 | 8977篇 |
2012年 | 8503篇 |
2011年 | 8174篇 |
2010年 | 7266篇 |
2009年 | 5701篇 |
2008年 | 6350篇 |
2007年 | 5930篇 |
2006年 | 5754篇 |
2005年 | 5560篇 |
2004年 | 5416篇 |
2003年 | 5157篇 |
2002年 | 4860篇 |
2001年 | 1146篇 |
2000年 | 835篇 |
1999年 | 1137篇 |
1998年 | 1290篇 |
1997年 | 855篇 |
1996年 | 772篇 |
1995年 | 690篇 |
1994年 | 660篇 |
1993年 | 705篇 |
1992年 | 600篇 |
1991年 | 549篇 |
1990年 | 480篇 |
1989年 | 416篇 |
1988年 | 436篇 |
1987年 | 352篇 |
1986年 | 333篇 |
1985年 | 416篇 |
1984年 | 540篇 |
1983年 | 414篇 |
1982年 | 515篇 |
1981年 | 500篇 |
1980年 | 431篇 |
1979年 | 307篇 |
1978年 | 332篇 |
1977年 | 293篇 |
1976年 | 273篇 |
1975年 | 212篇 |
1974年 | 247篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
71.
72.
73.
74.
75.
Late Quaternary climate change,relict populations and present‐day refugia in the northern Atacama Desert: a case study from Quebrada La Higuera (18° S)
下载免费PDF全文
![点击此处可从《Journal of Biogeography》网站下载免费的PDF全文](/ch/ext_images/free.gif)
76.
Hydrobiologia - To observe effects on the phosphorus retention mechanisms of a lake after re-colonisation by macrophytes, Potamogeton crispus L. and Elodea canadensis Michx. were planted in lab... 相似文献
77.
78.
Ruxandra Ion L. Telvi Jean-Louis Chaussain Jacques Patrick Barbet Manoel Nunes Anne Safar Marie-Odile Réthoré Marc Fellous Ken McElreavey 《Human genetics》1998,102(2):151-156
In 46,XY individuals, testes are determined by the activity of the SRY gene (sex-determining region Y), located on the short arm of the Ychromosome. The other genetic components of the cascade
that leads to testis formation are unknown and may be located on the Xchromosome or on the autosomes. Evidence for the existence
of several loci associated with failure of male sexual development is indicated by reports of 46,XY gonadal dysgenesis associated
with structural abnormalities of the Xchromosome or of autosomes (chromosomes9, 10, 11 and 17). In this report, we describe
the investigation of a child presenting with multiple congenital abnormalities, mental retardation and partial testicular
failure. The patient had a homogeneous de novo 46,XY,inv dup(9)(pter→p24.1::p21.1 →p23.3::p24.1→qter) chromosome complement.
No deletion was found by either cytogenetic or molecular analysis. The SRY gene and DSS region showed no abnormalities. Southern blotting dosage analysis with 9p probes and fluorescent in situ hybridisation data
indicated that the distal breakpoint of the duplicated fragment was located at 9p24.1, proximal to the SNF2 gene. We therefore suggest that a gene involved in normal testicular development and/or maintenance is present at this position
on chromosome 9.
Received: 20 January 1997 / Accepted: 5 November 1997 相似文献
79.
80.
N. Rocks C. Estrella G. Paulissen F. Quesada‐Calvo C. Gilles M. M. Guéders C. Crahay J.‐M. Foidart P. Gosset A. Noel D. D. Cataldo 《Cell proliferation》2008,41(6):988-1001
Abstract. Objectives: The ADAMs (a disintegrin and metalloproteinase) enzymes compose a family of membrane‐bound proteins characterized by their multi‐domain structure and ADAM‐12 expression is elevated in human non‐small cell lung cancers. The aim of this study was to investigate the roles played by ADAM‐12 in critical steps of bronchial cell transformation during carcinogenesis. Materials and methods: To assess the role of ADAM‐12 in tumorigenicity, BEAS‐2B cells were transfected with a plasmid encoding human full‐length ADAM‐12 cDNA, and then the effects of ADAM‐12 overexpression on cell behaviour were explored. Treatment of clones with heparin‐binding epidermal growth factor (EGF)‐like growth factor (HB‐EGF) neutralizing antibodies as well as an EGFR inhibitor allowed the dissection of mechanisms regulating cell proliferation and apoptosis. Results: Overexpression of ADAM‐12 in BEAS‐2B cells promoted cell proliferation. ADAM‐12 overexpressing clones produced higher quantities of HB‐EGF in their culture medium which may rely on membrane‐bound HB‐EGF shedding by ADAM‐12. Targeting HB‐EGF activity with a neutralizing antibody abrogated enhanced cell proliferation in the ADAM‐12 overexpressing clones. In sharp contrast, targeting of amphiregulin, EGF or transforming growth factor‐α failed to influence cell proliferation; moreover, ADAM‐12 transfectants were resistant to etoposide‐induced apoptosis and the use of a neutralizing antibody against HB‐EGF activity restored rates of apoptosis to be similar to controls.Conclusions: ADAM‐12 contributes to enhancing HB‐EGF shedding from plasma membranes leading to increased cell proliferation and reduced apoptosis in this bronchial epithelial cell line. 相似文献