全文获取类型
收费全文 | 1324篇 |
免费 | 108篇 |
专业分类
1432篇 |
出版年
2023年 | 10篇 |
2022年 | 18篇 |
2021年 | 36篇 |
2020年 | 19篇 |
2019年 | 25篇 |
2018年 | 30篇 |
2017年 | 25篇 |
2016年 | 46篇 |
2015年 | 55篇 |
2014年 | 86篇 |
2013年 | 97篇 |
2012年 | 98篇 |
2011年 | 97篇 |
2010年 | 43篇 |
2009年 | 45篇 |
2008年 | 79篇 |
2007年 | 54篇 |
2006年 | 64篇 |
2005年 | 59篇 |
2004年 | 52篇 |
2003年 | 59篇 |
2002年 | 57篇 |
2001年 | 22篇 |
2000年 | 20篇 |
1999年 | 22篇 |
1998年 | 8篇 |
1997年 | 11篇 |
1996年 | 8篇 |
1995年 | 11篇 |
1994年 | 5篇 |
1992年 | 12篇 |
1991年 | 12篇 |
1990年 | 11篇 |
1989年 | 8篇 |
1988年 | 5篇 |
1987年 | 15篇 |
1986年 | 13篇 |
1985年 | 7篇 |
1984年 | 9篇 |
1983年 | 7篇 |
1981年 | 10篇 |
1980年 | 4篇 |
1979年 | 9篇 |
1978年 | 3篇 |
1975年 | 4篇 |
1974年 | 3篇 |
1973年 | 3篇 |
1968年 | 8篇 |
1967年 | 4篇 |
1965年 | 3篇 |
排序方式: 共有1432条查询结果,搜索用时 15 毫秒
1.
Emma Bricchi Marco Fornaciari Claudia Giannoni Francesca Greco Daniela Fascini Giuseppe Frenguelli Gianfranco Mincigrucci Bruno Romano 《Aerobiologia》1992,8(3):401-406
Summary Gramineae pollination from a pollen monitoring station located in the eastern suburb of Perugia and meteorological correlations are reported. The data refers to the year 1989. Grass pollen peak pollination was from May to July; in this period the influence of relative humidity and of temperature on pollen concentration was very high. Phenological observations, to identify the time of maximum stamen extension in the most common genera in the area, are also reported. During the period of investigation the counts of pollen grains over four-hour periods showed a regular diurnal rhythm with peaks of concentration in the four-hour period 16.00–20.00. Aerosporological data and meteorological data related to four-hour periods were correlated following different criteria. 相似文献
2.
A Bobba I Munno B Greco N M Pellegrino P Riccio E Jirillo E Quagliariello 《Biochemical and biophysical research communications》1991,180(2):1125-1129
We have applied a double tagging system in order to study whether purified myelin basic protein is able to adhere to normal human peripheral T lymphocytes without the need to purify cells. Evaluation of myelin basic protein adherence to peripheral blood mononuclear cells was determined with biotinylated myelin basic protein and fluoresceinated avidin, and lymphocyte population was identified by the corresponding phycoerythrinated monoclonal antibody. The observed adherence of myelin basic protein to T lymphocytes was found to depend on protein conformation. 相似文献
3.
4.
5.
The circadian rhythm of the N-terminus and C-terminus of the atrial natriuretic factor prohormone 总被引:1,自引:0,他引:1
D L Vesely E L Kanabrocki R B Sothern L E Scheving T H Tsai J Greco D L Bushell E Kaplan J Rumbyrt R P Sturtevant 《Chronobiology international》1990,7(1):51-57
Circadian variation in the circulating concentrations of the N-terminal and C-terminal portions of the atrial natriuretic factor prohormone (pro ANF) was evaluated in 8 men, ages 41-47, who have been followed for 19 years with respect to circadian variation in physiological variables including blood pressure and clinical chemistries. The N-terminus of the ANF prohormone contains two peptides consisting of amino acids 1-30 and 31-67 while the C-terminus contains 1 peptide (amino acids 99-126) of this 126 amino acid prohormone which lower blood pressure and have natriuretic properties. To determine if either the N-terminus and/or the C-terminus of the prohormone have a circadian variation in their circulating plasma concentrations these 8 men had blood samples obtained for radiommunoassay every 3 hr during a 24-hr period. Three radiommunoassays which immunologically recognize (1) the whole N-terminus (i.e. amino acids 1-98), (2) the midportion of the N-terminus (amino acids 31-67) and (3) the C-terminus (amino acids 99-126) of the ANF prohormone were utilized. The whole N-terminus, the midportion of the N-terminus which circulates after being proteolytically cleaved from the rest of the N-terminus, and the C-terminus each had a peak circulating concentration between 0400 and 0700 which were significantly (P less than 0.001) higher than their concentrations at any other time throughout the 24-hr period.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
6.
Anna Maria Greco Pasquale Gambardella Raffaella Sticchi Diego D'aponte Pietro De Franciscis 《Chronobiology international》1988,5(3):217-225
Circadian rhythms of serotonin (5HT), its precursors tryptophan (TP) and 5-hydroxy-tryptophan (5HTP) and its acid catabolite 5-hydroxy-indoleacetic acid (5HIAA), were determined in the hypothalamus of control rats and rats which had been treated continuously with subcutaneous imipramine (10 mg/kg/day) for 2 weeks.
Rats were individually housed and entrained to LD12:12. Controls showed the 5HT and TP peaks in the light and dark periods respectively, as reported in the literature, but no inverted correlation (antiphase) between SHT and 5HIAA rhythms.
Imipramine significantly modified circadian rhythm characteristics: the 5HT acrophase was advanced, that of TP and 5HIAA was delayed. Imipramine also significantly increased hypothalamic SHT and TP concentrations. 相似文献
Rats were individually housed and entrained to LD12:12. Controls showed the 5HT and TP peaks in the light and dark periods respectively, as reported in the literature, but no inverted correlation (antiphase) between SHT and 5HIAA rhythms.
Imipramine significantly modified circadian rhythm characteristics: the 5HT acrophase was advanced, that of TP and 5HIAA was delayed. Imipramine also significantly increased hypothalamic SHT and TP concentrations. 相似文献
7.
M H Carstens R J Greco D J Hurwitz D E Tolhurst 《Plastic and reconstructive surgery》1991,87(4):615-626
The anatomic boundaries and vascular supply of the subgaleal fascia have been described previously. The thin and malleable subgaleal fascia was selected for difficult reconstructive problems in seven patients. This flap has been based on either the supraorbital or the superficial temporal vascular leash. The subgaleal fascia is readily dissected from superficial galea and deep periosteum, leaving behind a well-vascularized scalp and a skin-graftable calvarium. The flap conforms to a cartilage framework for ear reconstruction. It takes a skin graft well. The subgaleal fascia can patch dural defects and fill sinus dead space. It has been used to augment facial contour. Free vascularized transfer of the subgaleal fascia has included the temporoparietal fascia, which was partially split from the subgaleal fascia for bilobed flap resurfacing of the hand. The subgaleal fascial flap should be considered when ultrathin, vascularized coverage is needed. 相似文献
8.
Chromosomal localization of human genes required for G1 progression in mammalian cells 总被引:3,自引:0,他引:3
A Greco M Ittmann C Barletta C Basilico C M Croce L A Cannizzaro K Huebner 《Genomics》1989,4(3):240-245
Specific probes derived from the human genes that complement the mutations of two independent temperature-sensitive (ts) mutants of the BHK-21 hamster cell line were used to determine the chromosomal locations of the loci in the human genome. The ts11 gene, which complements a mutation that blocks progression through the G1 phase of the cell cycle and which has now been identified as the structural gene for asparagine synthetase, is a member of a small gene/pseudogene family with four members. In a rodent-human somatic cell hybrid panel, the ts11 genomic locus from which the genomic probe derives segregates with human chromosome region 7cen----7q35, proximal to the TCR beta locus. In situ hybridization maps this locus more precisely to the q21-31 region of chromosome 7. Two other members of the gene family detected by the ts11 probe segregate concordantly with chromosome region 8pter----8q24 and chromosome region 21pter----21q22. Similar experiments using the same rodent-human hybrid panel conducted with a probe identifying the tsBN51 gene, which also encodes a function necessary for G1 progression, mapped this locus to human chromosome 8, proximal to the large amplification unit encompassing the c-myc gene of Colo320 cells. Chromosomal in situ hybridization of the tsBN51 probe confirmed the localization of this gene to chromosome 8, with the most likely location of the gene being 8q21. 相似文献
9.
The DNA rearrangement that generates the TRK-T3 oncogene involves a novel gene on chromosome 3 whose product has a potential coiled-coil domain. 总被引:3,自引:1,他引:2 下载免费PDF全文
A Greco C Mariani C Miranda A Lupas S Pagliardini M Pomati M A Pierotti 《Molecular and cellular biology》1995,15(11):6118-6127
Oncogenic rearrangements of the NTRK1 gene (also designated TRKA), encoding one of the receptors for the nerve growth factor, are frequently detected in thyroid carcinomas. Such rearrangements fuse the NTRK1 tyrosine kinase domain to 5'-end sequences belonging to different genes. In previously reported studies we have demonstrated that NTRK1 oncogenic activation involves two genes, TPM3 and TPR, both localized similarly to the receptor tyrosine kinase, on the q arm of chromosome 1. Here we report the characterization of a novel NTRK1-derived thyroid oncogene, named TRK-T3. A cDNA clone, capable of transforming activity, was isolated from a transformant cell line. Sequence analysis revealed that TRK-T3 contains 1,412 nucleotides of NTRK1 preceded by 598 nucleotides belonging to a novel gene that we have named TFG (TRK-fused gene). The TRK-T3 amino acid sequence displays, within the TFG region, a coiled-coil motif that could endow the oncoprotein with the capability to form complexes. The TRK-T3 oncogene encodes a 68-kDa cytoplasmic protein reacting with NTRK1-specific antibodies. By sedimentation gradient experiments the TRK-T3 oncoprotein was shown to form, in vivo, multimeric complexes, most likely trimers or tetramers. The TFG gene is ubiquitously expressed and is located on chromosome 3. The breakpoint producing the TRK-T3 oncogene occurs within exons of both the TFG gene and the NTRK1 gene and produces a chimeric exon that undergoes alternative splicing. Molecular analysis of the NTRK1 rearranged fragments indicated that the chromosomal rearrangement is reciprocal and balanced and involves loss of a few nucleotides of germ line sequences. 相似文献
10.
Trace gas exchange over terrestrial ecosystems: methods and perspectives in micrometeorology 总被引:1,自引:0,他引:1
Moncrieff John; Valentini Riccardo; Greco Susanna; Guenther Seufert; Ciccioli Paolo 《Journal of experimental botany》1997,48(5):1133-1142
Quantification of the surface-atmosphere exchange of trace gasesis recognized as an essential prerequisite to understandingthe role of the biosphere in the global climate system. Amongthe micrometeorological methods available to measure surface-atmospherefluxes, the aerodynamic gradient, the energy balance/Bowen ratio,the eddy covariance and the eddy accumulation methods are themost widely employed. This brief review describes the theoreticalbackground and the practical applications of these methodologiesand is particularly directed to plant ecophysiologists, ecologistsand botanists who may be interested in scaling biological processesto the canopy level. Key words: Trace gas exchange, biosphere, surface-atmosphere fluxes, aerodynamic gradient, Bowen ratio, eddy covariance, eddy accumulation, micrometeorology 相似文献