全文获取类型
收费全文 | 2017篇 |
免费 | 189篇 |
国内免费 | 1篇 |
专业分类
2207篇 |
出版年
2023年 | 7篇 |
2022年 | 15篇 |
2021年 | 23篇 |
2020年 | 23篇 |
2019年 | 25篇 |
2018年 | 19篇 |
2017年 | 27篇 |
2016年 | 55篇 |
2015年 | 82篇 |
2014年 | 83篇 |
2013年 | 134篇 |
2012年 | 143篇 |
2011年 | 146篇 |
2010年 | 95篇 |
2009年 | 76篇 |
2008年 | 99篇 |
2007年 | 103篇 |
2006年 | 98篇 |
2005年 | 125篇 |
2004年 | 87篇 |
2003年 | 87篇 |
2002年 | 127篇 |
2001年 | 47篇 |
2000年 | 27篇 |
1999年 | 28篇 |
1998年 | 43篇 |
1997年 | 32篇 |
1996年 | 32篇 |
1995年 | 30篇 |
1994年 | 27篇 |
1993年 | 34篇 |
1992年 | 18篇 |
1991年 | 14篇 |
1990年 | 17篇 |
1989年 | 19篇 |
1988年 | 13篇 |
1987年 | 9篇 |
1986年 | 10篇 |
1985年 | 7篇 |
1984年 | 13篇 |
1983年 | 15篇 |
1982年 | 14篇 |
1981年 | 10篇 |
1980年 | 8篇 |
1978年 | 7篇 |
1975年 | 6篇 |
1974年 | 4篇 |
1973年 | 4篇 |
1972年 | 6篇 |
1960年 | 4篇 |
排序方式: 共有2207条查询结果,搜索用时 15 毫秒
61.
62.
Willem Bintig Judith Baumgart Wilhelm J. Walter Alexander Heisterkamp Holger Lubatschowski Anaclet Ngezahayo 《Journal of bioenergetics and biomembranes》2009,41(1):85-94
Purinergic signalling in rat GFSHR-17 granulosa cells was characterised by Ca2+-imaging and perforated patch-clamp. We observed a resting intracellular Ca2+-concentration ([Ca2+]i) of 100 nM and a membrane potential of −40 mV. This was consistent with high K+− and Cl− permeability and a high intracellular Cl− concentration of 40 mM. Application of ATP for 5–15 s every 3 min induced repeated [Ca2+]i increases and a 30 mV hyperpolarization. The phospholipase C inhibitor U73122 or the IP3-receptor antagonist 2-aminoethoethyl diphenyl borate suppressed ATP responses. Further biochemical and pharmacological experiments
revealed that ATP responses were related to stimulation of P2Y2 and P2Y4 receptors and that the [Ca2+]i increase was a prerequisite for hyperpolarization. Inhibitors of Ca2+-activated channels or K+ channels did not affect the ATP-evoked responses. Conversely, inhibitors of Cl− channels hyperpolarized cells to −70 mV and suppressed further ATP-evoked hyperpolarization. We propose that P2Y2 and P2Y4 receptors in granulosa cells modulate Cl− permeability by regulating Ca2+-release. 相似文献
63.
Sander A. Peters Erwin Datema Dóra Szinay Marjo J. van Staveren Elio G.W.M. Schijlen Jan C. van Haarst Thamara Hesselink Marleen H.C. Abma-Henkens Yuling Bai Hans de Jong Willem J. Stiekema René M. Klein Lankhorst Roeland C.H.J. van Ham 《The Plant journal : for cell and molecular biology》2009,58(5):857-869
64.
Zoetendal EG Heilig HG Klaassens ES Booijink CC Kleerebezem M Smidt H de Vos WM 《Nature protocols》2006,1(2):870-873
The human gastrointestinal (GI) tract contains a complex microbial community that develops in time and space. The most widely used approaches to study microbial diversity and activity are all based on the analysis of nucleic acids, DNA, rRNA and mRNA. Here, we present a DNA isolation protocol that is suitable for a wide variety of GI tract samples, including biopsies with minute amounts of material. The protocol is set up in such a way that sampling can be performed outside the laboratory, which offers possibilities for implementation in large intervention studies. The DNA isolation is based on mechanical disruption, followed by isolation of nucleic acids using phenol:chloroform:isoamylalcohol extraction. In addition, it includes an alternative DNA isolation protocol that is based on a commercial kit. These protocols have all been successfully used in our laboratory, resulting in isolation of DNA of sufficient quality for microbial diversity studies. Depending on the number of samples and sample type, the whole procedure will take approximately 2.5-4 hours. 相似文献
65.
Darwin J. Prockop Malcolm Brenner Willem E. Fibbe Edwin Horwitz Katarina Le Blanc Donald G. Phinney Paul J. Simmons Luc Sensebe Armand Keating 《Cytotherapy》2010,12(5):576-578
We address the issue of the potential for malignant transformation of cultured mesenchymal stromal cells (MSC) commonly used in clinical cell-therapy protocols and describe the culture conditions under which tumorigenesis is likely to be an extremely uncommon event. 相似文献
66.
Influence of BCG vaccine strain on the immune response and protection against tuberculosis 总被引:3,自引:0,他引:3
The Bacille Calmette–Guérin (BCG) vaccine has been used for more than 80 years to protect against tuberculosis. Worldwide, over 90% of children are immunized with BCG, making it the most commonly administered vaccine, with more than 120 million doses used each year. Although new tuberculosis vaccines are under investigation, BCG will remain the cornerstone of the strategy to fight the worsening tuberculosis pandemic for the foreseeable future. The recent delineation of genetic differences between BCG vaccine strains has renewed interest in the influence of the vaccine strain on the protective efficacy against tuberculosis. This review critically examines the data from animal and human studies comparing BCG vaccine strains. Although there is good evidence to support the notion that the induced immune response and protection afforded against tuberculosis differs between BCG vaccine strains, currently, there are insufficient data to favour or recommend one particular strain. Identifying BCG strains with superior protection would have a dramatic effect on tuberculosis control at a population level: a small increment in protection provided by BCG immunization will prevent large numbers of cases of severe tuberculosis and deaths, particularly in children. 相似文献
67.
Sophie Garnier Vinh Truong Jessy Brocheton Tanja Zeller Maxime Rovital Philipp S. Wild Andreas Ziegler The Cardiogenics Consortium Thomas Munzel Laurence Tiret Stefan Blankenberg Panos Deloukas Jeannette Erdmann Christian Hengstenberg Nilesh J. Samani Heribert Schunkert Willem H. Ouwehand Alison H. Goodall Fran?ois Cambien David-Alexandre Trégou?t 《PLoS genetics》2013,9(1)
68.
69.
Wounding of plants by insects is often mimicked in the laboratory by mechanical means such as cutting or crushing, and has not been compared directly with other forms of biotic stress such as virus infection. To compare the response of plants to these types of biotic and abiotic stress, trypsin inhibitor (TI) activity induced locally and systemically in mature tobacco (Nicotiana tabacum L.) and tomato (Lycopersicon esculentum L.) plants was followed for 12 days. In tobacco, cutting, crushing and insect feeding all induced comparable levels of TI activity of approx. 5 nmol·(mg leaf protein)?1 in wounded leaves, while tobacco mosaic virus (TMV) infection of tobacco induced 10-fold lower amounts in the infected leaves. In tomato, feeding by insects also led to the induction of a level of TI activity of 5 nmol·(mg leaf protein)?1. In contrast, both cutting and crushing of tomato leaves induced 10-fold higher amounts. These data show that biotic stress, in the form of insect feeding and TMV infection, and abiotic stress, in the form of wounding, have different effects on local levels of induced TI activity in mature tobacco and tomato plants. Irrespective of the type of wounding, in neither tobacco nor tomato could systemic induction of TI activity be observed in nearby unwounded leaves, which suggests that systemic induction of TI activity in mature tobacco and tomato plants is different from systemic TI induction in seedlings. Wounding of tobacco leaves, however, did increase the responsiveness to wounding elsewhere in the plant, as measured by an increased induction of TI activity. 相似文献
70.
Willem Rensink Amy Hart Jia Liu Shu Ouyang Victoria Zismann C Robin Buell 《Génome》2005,48(4):598-605