全文获取类型
收费全文 | 1115篇 |
免费 | 101篇 |
出版年
2023年 | 4篇 |
2022年 | 8篇 |
2021年 | 21篇 |
2020年 | 6篇 |
2019年 | 10篇 |
2018年 | 19篇 |
2017年 | 16篇 |
2016年 | 27篇 |
2015年 | 42篇 |
2014年 | 53篇 |
2013年 | 69篇 |
2012年 | 115篇 |
2011年 | 74篇 |
2010年 | 56篇 |
2009年 | 63篇 |
2008年 | 83篇 |
2007年 | 69篇 |
2006年 | 91篇 |
2005年 | 71篇 |
2004年 | 64篇 |
2003年 | 62篇 |
2002年 | 60篇 |
2001年 | 14篇 |
2000年 | 7篇 |
1999年 | 15篇 |
1998年 | 21篇 |
1997年 | 17篇 |
1996年 | 7篇 |
1995年 | 9篇 |
1994年 | 4篇 |
1993年 | 5篇 |
1992年 | 4篇 |
1991年 | 4篇 |
1990年 | 8篇 |
1989年 | 3篇 |
1988年 | 1篇 |
1986年 | 2篇 |
1985年 | 4篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1980年 | 2篇 |
1978年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有1216条查询结果,搜索用时 359 毫秒
951.
Arabinoxylans (AX) and (1→3),(1→4)-β-glucans are major components of wheat endosperm cell walls. Their chemical heterogeneity has been described but little is known about the sequence of their deposition in cell walls during endosperm development. The time course and pattern of deposition of the (1→3) and (1→3),(1→4)-β-glucans and AX in the endosperm cell walls of wheat (Triticum aestivum L. cv. Recital) during grain development was studied using specific antibodies. At approximately 45°D (degree-days) after anthesis the developing walls contained (1→3)-β-glucans but not (1→3),(1→4)-β-glucans. In contrast, (1→3),(1→4)-β-glucans occurred widely in the walls of maternal tissues. At the end of the cellularization stage (72°D), (1→3)-β-glucan epitopes disappeared and (1→3),(1→4)-β-glucans were found equally distributed in all thin walls of wheat endosperm. The AX were detected at the beginning of differentiation (245°D) in wheat endosperm, but were missing in previous stages. However, epitopes related to AX were present in nucellar epidermis and cross cells surrounding endosperm at all stages but not detected in the maternal outer tissues. As soon as the differentiation was apparent, the cell walls exhibited a strong heterogeneity in the distribution of polysaccharides within the endosperm. 相似文献
952.
Pannetier M Tilly G Kocer A Hudrisier M Renault L Chesnais N Costa J Le Provost F Vaiman D Vilotte JL Pailhoux E 《FEBS letters》2006,580(15):3715-3720
The testis-determining gene SRY is not well-conserved among mammals, particularly between mouse and other mammals, both in terms of protein structure and of expression regulation. To evaluate SRY phylogenic conservation in regards to its function, we expressed the goat gene (gSRY) in XX transgenic mouse gonads. Here, we show that gSRY induces testis formation, despite a goat expression profile. Our results demonstrate that sex-reversal can be induced in XX-mice by a non-mouse SRY thus suggesting a conserved molecular mechanism of action of this testis-determining gene across mammalian species. 相似文献
953.
Expression and chromosomal localization of the Requiem gene 总被引:2,自引:0,他引:2
Theodore G. Gabig Colin D. Crean Alison Klenk Haiyan Long Neal G. Copeland Debra J. Gilbert Nancy A. Jenkins Danielle Quincey Fabienne Parente Françoise Lespinasse Georges F. Carle Patrick Gaudray Chang X. Zhang Alain Calender Jo Hoeppener Koen Kas Rajesh V. Thakker Filip Farnebo Bin T. Teh Catharina Larsson Fredrik Piehl Jacob Lagercrantz Shideh Khodaei Emma Carson Günther Weber 《Mammalian genome》1998,9(8):660-665
954.
Brad A. Seibel Fabienne Chausson Francois H. Lallier Franck Zal James J. Childress 《Experimental Biology Online》1999,4(1):1-10
The functional properties of the haemocyanin ofVampyroteuthis infernalis (Cephalopoda: Vampyromorpha), measured at 5 °C, are reported and discussed in relation to hypoxia. The oxygen affinity of this haemocyanin (P50=0.47−0.55 kPa) is higher than any previously measured for a cephalopod. The high cooperativity (n50=2.20−2.23) and Bohr coefficient (−0.22) suggest a true transport function for this haemocyanin. This high-affinity haemocyanin, in conjunction with moderate gill diffusion capacity, provides a sufficient oxygen gradient from the environment to the blood to support the low routine oxygen consumption rate of V. infernalis 相似文献
955.
Geoffrey Brioude Fabienne Brégeon Delphine Trousse Christophe Flaudrops Véronique Secq Florence De Dominicis Eric Chabrières Xavier-Benoit D’journo Didier Raoult Pascal-Alexandre Thomas 《PloS one》2016,11(5)
ObjectiveDespite recent advances in imaging and core or endoscopic biopsies, a percentage of patients have a major lung resection without diagnosis. We aimed to assess the feasibility of a rapid tissue preparation/analysis to discriminate cancerous from non-cancerous lung tissue.MethodsFresh sample preparations were analyzed with the Microflex LTTM MALDI-TOF analyzer. Each main reference spectra (MSP) was consecutively included in a database. After definitive pathological diagnosis, each MSP was labeled as either cancerous or non-cancerous (normal, inflammatory, infectious nodules). A strategy was constructed based on the number of concordant responses of a mass spectrometry scoring algorithm. A 3-step evaluation included an internal and blind validation of a preliminary database (n = 182 reference spectra from the 100 first patients), followed by validation on a whole cohort database (n = 300 reference spectra from 159 patients). Diagnostic performance indicators were calculated.Results127 cancerous and 173 non-cancerous samples (144 peripheral biopsies and 29 inflammatory or infectious lesions) were processed within 30 minutes after biopsy sampling. At the most discriminatory level, the samples were correctly classified with a sensitivity, specificity and global accuracy of 92.1%, 97.1% and 95%, respectively.ConclusionsThe feasibility of rapid MALDI-TOF analysis, coupled with a very simple lung preparation procedure, appears promising and should be tested in several surgical settings where rapid on-site evaluation of abnormal tissue is required. In the operating room, it appears promising in case of tumors with an uncertain preoperative diagnosis and should be tested as a complementary approach to frozen-biopsy analysis. 相似文献
956.
Blood leukocytes can exhibit extensive morphological changes during their passage through small capillary vessels. The human monocytic THP-1 cell line was used to explore the metabolic dependence of these changes in shape. Cells were aspirated into micropipettes for determination of the rate of protrusion formation. They were then released and the kinetics of morphological recovery was studied. Results were consistent with Evans’ model (Blood 64:1028, 1984) of a viscous liquid droplet surrounded by a tensile membrane. The estimated values of cytoplasmic viscosity and membrane tension were 162 Pa.s and 0.0142 mN/m respectively. The influence of metabolic inhibitors on cell mechanical behavior was then studied: results strongly suggested that deformation involved two sequential phases. The cell elongation rate measured during the first 30 s following the onset of aspiration was unaffected by azide, an inhibitor of energy production, and it was about doubled by cytochalasin D, a microfilament inhibitor, and colchicine, a microtubule inhibitor. However, during the following 2 min, deformation was almost abolished in cells treated with azide and cytochalasin D, whereas the protrusion of control cells exhibited an approximately threefold increase in length. It is concluded that, although cells seemed to deform as passive objects, active metabolic processes were required to allow extensive morphological changes triggered by external forces. 相似文献
957.
958.
959.
Guillon F Bouchet B Jamme F Robert P Quéméner B Barron C Larré C Dumas P Saulnier L 《Journal of experimental botany》2011,62(3):1001-1015
The wild grass Brachypodium distachyon has been proposed as an alternative model species for temperate cereals. The present paper reports on the characterization of B. distachyon grain, placing emphasis on endosperm cell walls. Brachypodium distachyon is notable for its high cell wall polysaccharide content that accounts for ~52% (w/w) of the endosperm in comparison with 2-7% (w/w) in other cereals. Starch, the typical storage polysaccharide, is low [<10% (w/w)] in the endosperm where the main polysaccharide is (1-3) (1-4)-β-glucan [40% (w/w) of the endosperm], which in all likelihood plays a role as a storage compound. In addition to (1-3) (1-4)-β-glucan, endosperm cells contain cellulose and xylan in significant amounts. Interestingly, the ratio of ferulic acid to arabinoxylan is higher in B. distachyon grain than in other investigated cereals. Feruloylated arabinoxylan is mainly found in the middle lamella and cell junction zones of the storage endosperm, suggesting a potential role in cell-cell adhesion. The present results indicate that B. distachyon grains contain all the cell wall polysaccharides encountered in other cereal grains. Thus, due to its fully sequenced genome, its short life cycle, and the genetic tools available for mutagenesis/transformation, B. distachyon is a good model to investigate cell wall polysaccharide synthesis and function in cereal grains. 相似文献
960.
Capotosti F Guernier S Lammers F Waridel P Cai Y Jin J Conaway JW Conaway RC Herr W 《Cell》2011,144(3):376-388
The human epigenetic cell-cycle regulator HCF-1 undergoes an unusual proteolytic maturation process resulting in stably associated HCF-1(N) and HCF-1(C) subunits that regulate different aspects of the cell cycle. Proteolysis occurs at six centrally located HCF-1(PRO)-repeat sequences and is important for activation of HCF-1(C)-subunit functions in M phase progression. We show here that the HCF-1(PRO) repeat is recognized by O-linked β-N-acetylglucosamine transferase (OGT), which both O-GlcNAcylates the HCF-1(N) subunit and directly cleaves the HCF-1(PRO) repeat. Replacement of the HCF-1(PRO) repeats by a heterologous proteolytic cleavage signal promotes HCF-1 proteolysis but fails to activate HCF-1(C)-subunit M phase functions. These results reveal an unexpected role of OGT in HCF-1 proteolytic maturation and an unforeseen nexus between OGT-directed O-GlcNAcylation and proteolytic maturation in HCF-1 cell-cycle regulation. 相似文献