全文获取类型
收费全文 | 3445篇 |
免费 | 347篇 |
国内免费 | 3篇 |
出版年
2022年 | 17篇 |
2021年 | 44篇 |
2020年 | 34篇 |
2019年 | 30篇 |
2018年 | 58篇 |
2017年 | 56篇 |
2016年 | 79篇 |
2015年 | 139篇 |
2014年 | 168篇 |
2013年 | 171篇 |
2012年 | 231篇 |
2011年 | 215篇 |
2010年 | 145篇 |
2009年 | 136篇 |
2008年 | 191篇 |
2007年 | 193篇 |
2006年 | 217篇 |
2005年 | 184篇 |
2004年 | 170篇 |
2003年 | 168篇 |
2002年 | 174篇 |
2001年 | 71篇 |
2000年 | 44篇 |
1999年 | 48篇 |
1998年 | 46篇 |
1997年 | 35篇 |
1996年 | 42篇 |
1995年 | 42篇 |
1994年 | 44篇 |
1993年 | 29篇 |
1992年 | 62篇 |
1991年 | 45篇 |
1990年 | 39篇 |
1989年 | 41篇 |
1988年 | 32篇 |
1987年 | 22篇 |
1986年 | 25篇 |
1985年 | 31篇 |
1984年 | 19篇 |
1983年 | 21篇 |
1982年 | 21篇 |
1980年 | 13篇 |
1979年 | 17篇 |
1978年 | 14篇 |
1977年 | 13篇 |
1976年 | 14篇 |
1974年 | 14篇 |
1973年 | 11篇 |
1972年 | 11篇 |
1971年 | 12篇 |
排序方式: 共有3795条查询结果,搜索用时 15 毫秒
921.
Belowground volatiles facilitate interactions between plant roots and soil organisms 总被引:1,自引:0,他引:1
Many interactions between organisms are based on the emission and perception of volatiles. The principle of using volatile
metabolites as communication signals for chemo-attractant or repellent for species-specific interactions or mediators for
cell-to-cell recognition does not stop at an apparently unsuitable or inappropriate environment. These infochemicals do not
only diffuse through the atmosphere to process their actions aboveground, but belowground volatile interactions are similarly
complex. This review summarizes various eucaryotes (e.g., plant (roots), invertebrates, fungi) and procaryotes (e.g., rhizobacteria)
which are involved in these volatile-mediated interactions. The soil volatiles cannot be neglected anymore, but have to be
considered in the future as valuable infochemicals to understand the entire integrity of the ecosystems. 相似文献
922.
Stefan Mayr Franziska Schwienbacher Barbara Beikircher Birgit Dämon 《Protoplasma》2010,243(1-4):137-143
Chrysomyxa rhododendri is a rust which infects Picea abies growing near the alpine timberline. Attacked needles are normally shed, but few remain on shoots. We hypothesised that these needles increase transpiration of Picea during winter. Partly damaged, completely damaged and healthy needles of an infected tree as well as healthy needles of a resistant tree were compared in a microscopy analysis, and needle conductance of shoots was measured gravimetrically. Despite needle shedding, more than 6% of needles remaining on infected tree shoots were damaged. Partly damaged needles showed local brownish areas in the periphery and completely damaged needles necrotic parenchyma and epidermal tissues. Cuticular conductance of affected shoots was up to 25.23?±?2.75 mmol m?2 s?1 at moderate water potential and thus twofold higher than in the resistant tree. Needle shedding reduces negative effects of Chrysomyxa infections during summer, but remaining damaged needles impair tree water relations in winter. 相似文献
923.
Matías D. Asención Diez Ana Demonte Jorge Giacomelli Sergio Garay Daniel Rodrígues Birgit Hofmann Hans-Juerguen Hecht Sergio A. Guerrero Alberto A. Iglesias 《Archives of microbiology》2010,192(2):103-114
Leptospira interrogans synthesizes a range of mannose-containing glycoconjugates relevant for its virulence. A prerequisite in the synthesis is
the availability of the GDP-mannose, produced from mannose-1-phosphate and GTP in a reaction catalyzed by GDP-mannose pyrophosphorylase.
The gene coding for a putative enzyme in L. interrogans was expressed in Escherichia coli BL21(DE3). The identity of this enzyme was confirmed by electrospray-mass spectroscopy, Edman sequencing and immunological
assays. Gel filtration chromatography showed that the dimeric form of the enzyme is catalytically active and stable. The recombinant
protein was characterized as a mannose-1-phosphate guanylyltransferase. S
0.5 for the substrates were determined both in GDP-mannose pyrophosphorolysis: 0.20 mM (GDP-mannose), 0.089 mM (PPi), and 0.47 mM;
and in GDP-mannose synthesis: 0.24 mM (GTP), 0.063 mM (mannose-1-phosphate), and 0.45 mM (Mg2+). The enzyme was able to produce GDP-mannose, IDP-mannose, UDP-mannose and ADP-glucose. We obtained a structural model of
the enzyme using as a template the crystal structure of mannose-1-phosphate guanylyltransferase from Thermus thermophilus HB8. Binding of substrates and cofactor in the model agree with the pyrophosphorylases reaction mechanism. Our studies provide
insights into the structure of a novel molecular target, which could be useful for detection of leptospirosis and for the
development of anti-leptospiral drugs. 相似文献
924.
Monte Carlo simulations are used to study the effect of spontaneous (intrinsic) twist on the conformation of topologically equilibrated minicircles of dsDNA. The twist, writhe, and radius of gyration distributions and their moments are calculated for different spontaneous twist angles and DNA lengths. The average writhe and twist deviate in an oscillatory fashion (with the period of the double helix) from their spontaneous values, as one spans the range between two neighboring integer values of intrinsic twist. Such deviations vanish in the limit of long DNA plasmids. 相似文献
925.
926.
927.
Sabine M Hölter Caroline Grabbe Vladimir Kirkin Noriyuki Koibuchi Christian Schultz Jan Rozman Daniela Hoeller Chun‐Hong Qiu Marina B Londoño Jun Ikezawa Peter Jedlicka Birgit Stein Stephan W Schwarzacher David P Wolfer Nicole Ehrhardt Rainer Heuchel Ioannis Nezis Andreas Brech Mirko H H Schmidt Helmut Fuchs Valerie Gailus‐Durner Martin Klingenspor Oliver Bogler Wolfgang Wurst Thomas Deller Martin Hrabé de Angelis Ivan Dikic 《The EMBO journal》2010,29(14):2421-2432
Despite extensive investigations of Cbl‐interacting protein of 85 kDa (CIN85) in receptor trafficking and cytoskeletal dynamics, little is known about its functions in vivo. Here, we report the study of a mouse deficient of the two CIN85 isoforms expressed in the central nervous system, exposing a function of CIN85 in dopamine receptor endocytosis. Mice lacking CIN85 exon 2 (CIN85Δex2) show hyperactivity phenotypes, characterized by increased physical activity and exploratory behaviour. Interestingly, CIN85Δex2 animals display abnormally high levels of dopamine and D2 dopamine receptors (D2DRs) in the striatum, an important centre for the coordination of animal behaviour. Importantly, CIN85 localizes to the post‐synaptic compartment of striatal neurons in which it co‐clusters with D2DRs. Moreover, it interacts with endocytic regulators such as dynamin and endophilins in the striatum. Absence of striatal CIN85 causes insufficient complex formation of endophilins with D2DRs in the striatum and ultimately decreased D2DR endocytosis in striatal neurons in response to dopamine stimulation. These findings indicate an important function of CIN85 in the regulation of dopamine receptor functions and provide a molecular explanation for the hyperactive behaviour of CIN85Δex2 mice. 相似文献
928.
Craig R. Yendrek Yi‐Ching Lee Viktoriya Morris Yan Liang Catalina I. Pislariu Graham Burkart Matthew H. Meckfessel Mohammad Salehin Hilary Kessler Heath Wessler Melanie Lloyd Heather Lutton Alice Teillet D. Janine Sherrier Etienne‐Pascal Journet Jeanne M. Harris Rebecca Dickstein 《The Plant journal : for cell and molecular biology》2010,62(1):100-112
Legume root architecture involves not only elaboration of the root system by the formation of lateral roots but also the formation of symbiotic root nodules in association with nitrogen‐fixing soil rhizobia. The Medicago truncatula LATD/NIP gene plays an essential role in the development of both primary and lateral roots as well as nodule development. We have cloned the LATD/NIP gene and show that it encodes a member of the NRT1(PTR) transporter family. LATD/NIP is expressed throughout the plant. pLATD/NIP‐GFP promoter–reporter fusions in transgenic roots establish the spatial expression of LATD/NIP in primary root, lateral root and nodule meristems and the surrounding cells. Expression of LATD/NIP is regulated by hormones, in particular by abscisic acid which has been previously shown to rescue the primary and lateral root meristem arrest of latd mutants. latd mutants respond normally to ammonium but have defects in responses of the root architecture to nitrate. Taken together, these results suggest that LATD/NIP may encode a nitrate transporter or transporter of another compound. 相似文献
929.
Nicolas Pietrancosta Albane Kessler Franck-Cyril Favre-Besse Nicolas Triballeau Thomas Quentin Bruno Giros Salah El Mestikawy Francine C. Acher 《Bioorganic & medicinal chemistry》2010,18(18):6922-6933
Vesicular glutamate transporters (VGLUTs) allow the loading of presynaptic glutamate vesicles and thus play a critical role in glutamatergic synaptic transmission. Rose Bengal (RB) is the most potent known VGLUT inhibitor (Ki 25 nM); therefore we designed, synthesized and tested in brain preparations, a series of analogs based on this scaffold. We showed that among the two tautomers of RB, the carboxylic and not the lactonic form is active against VGLUTs and generated a pharmacophore model to determine the minimal structure requirements. We also tested RB specificity in other neurotransmitter uptake systems. RB proved to potently inhibit VMAT (Ki 64 nM) but weakly VACHT (Ki >9.7 μM) and may be a useful tool in glutamate/acetylcholine co-transmission studies. 相似文献
930.