全文获取类型
收费全文 | 1158篇 |
免费 | 44篇 |
出版年
2023年 | 3篇 |
2022年 | 9篇 |
2021年 | 11篇 |
2020年 | 6篇 |
2019年 | 14篇 |
2018年 | 16篇 |
2017年 | 21篇 |
2016年 | 28篇 |
2015年 | 40篇 |
2014年 | 69篇 |
2013年 | 61篇 |
2012年 | 100篇 |
2011年 | 97篇 |
2010年 | 54篇 |
2009年 | 39篇 |
2008年 | 79篇 |
2007年 | 88篇 |
2006年 | 104篇 |
2005年 | 56篇 |
2004年 | 72篇 |
2003年 | 62篇 |
2002年 | 59篇 |
2001年 | 15篇 |
2000年 | 7篇 |
1999年 | 8篇 |
1998年 | 7篇 |
1997年 | 8篇 |
1996年 | 4篇 |
1995年 | 6篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1992年 | 6篇 |
1990年 | 3篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 4篇 |
1985年 | 5篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 5篇 |
1981年 | 4篇 |
1980年 | 1篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1977年 | 4篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1973年 | 2篇 |
1969年 | 1篇 |
排序方式: 共有1202条查询结果,搜索用时 15 毫秒
961.
Schmull M Miadlikowska J Pelzer M Stocker-Wörgötter E Hofstetter V Fraker E Hodkinson BP Reeb V Kukwa M Lumbsch HT Kauff F Lutzoni F 《Mycologia》2011,103(5):983-1003
The genus Lecidea Ach. sensu lato (sensu Zahlbruckner) includes almost 1200 species, out of which only 100 species represent Lecidea sensu stricto (sensu Hertel). The systematic position of the remaining species is mostly unsettled but anticipated to represent several unrelated lineages within Lecanoromycetes. This study attempts to elucidate the phylogenetic placement of members of this heterogeneous group of lichen-forming fungi and to improve the classification and phylogeny of Lecanoromycetes. Twenty-five taxa of Lecidea sensu lato and 22 putatively allied species were studied in a broad selection of 268 taxa, representing 48 families of Lecanoromycetes. Six loci, including four ribosomal and two protein-coding genes for 315- and 209-OTU datasets were subjected to maximum likelihood and Bayesian analyses. The resulting well supported phylogenetic relationships within Lecanoromycetes are in agreement with published phylogenies, but the addition of new taxa revealed putative rearrangements of several families (e.g. Catillariaceae, Lecanoraceae, Lecideaceae, Megalariaceae, Pilocarpaceae and Ramalinaceae). As expected, species of Lecidea sensu lato and putatively related taxa are scattered within Lecanoromycetidae and beyond, with several species nested in Lecanoraceae and Pilocarpaceae and others placed outside currently recognized families in Lecanorales and orders in Lecanoromycetidae. The phylogenetic affiliations of Schaereria and Strangospora are outside Lecanoromycetidae, probably with Ostropomycetidae. All species referred to as Lecidea sensu stricto based on morphology (including the type species, Lecidea fuscoatra [L.] Ach.) form, with Porpidia species, a monophyletic group with high posterior probability outside Lecanorales, Peltigerales and Teloschistales, in Lecanoromycetidae, supporting the recognition of order Lecideales Vain. in this subclass. The genus name Lecidea must be redefined to apply only to Lecidea sensu stricto and to include at least some members of the genus Porpidia. Based on morphological and chemical similarities, as well as the phylogenetic relationship of Lecidea pullata sister to Frutidella caesioatra, the new combination Frutidella pullata is proposed here. 相似文献
962.
Conlon JM Mechkarska M Coquet L Jouenne T Leprince J Vaudry H Kolodziejek J Nowotny N King JD 《Peptides》2011,32(4):664-669
Populations of the Chiricahua leopard frog Lithobates chiricahuensis (Ranidae) occupying regions in southern Arizona (southern range) are morphologically distinct from those from the Mogollon Rim of central Arizona (northern range) and a comparison of DNA sequences of mitochondrial genes has suggested that they may represent separate species. Peptidomic analysis of norepinephrine-stimulated skin secretions has led to the identification of six peptides with antimicrobial activity in samples from specimens from both groups. The primary structure of the peptides (esculentin-2CHa, ranatuerin-2CHa, -CHb, and -CHc, and brevinin-1CHa and -CHb) isolated from both southern and northern range frogs are identical consistent with the proposal that the two populations are conspecific. However, palustrin-2CHa and the atypical brevinin-1CHc (FFPTIAG*****LTKLFCA ITKKC), containing a five amino acid residue deletion, were identified only in secretions from southern range specimens. Consequently, there is some support for the proposal that the two populations are closely related but separate species but this support is relatively weak. Esculentin-2CHa (GFSSIFRGVAKFASKGLG KDLAKLGVDLVACKISKQC) displayed the highest antimicrobial potency (MIC ≤ 10 μM) against a variety of microorganisms and was only moderately hemolytic (LC50 = 150 μM). Cladistic analysis based upon the primary structures of brevinin-1 peptides indicates a close phylogenetic relationship between L. chiricahuensis, L. onca, and L. yavapaiensis. 相似文献
963.
Filipiak E Walczak-Jędrzejowska R Krupiński M Oszukowska E Marchlewska K Długoński J Kula K Słowikowska-Hilczer J 《Folia histochemica et cytobiologica / Polish Academy of Sciences, Polish Histochemical and Cytochemical Society》2011,49(4):685-689
The aim of this study was to assess the impact of di(n-butyl) phthalate (DBP) on the rat's prepubertal testis. Male Wistar rats were given daily subcutaneous injections with DBP (20 or 200 μg) or a vehicle from the 5th to the 15th postnatal day (pd). On the 16(th) pd, the rats were euthanized, and the testes were dissected, weighed, and paraffin embedded. The blood was collected to determine the serum levels of testosterone (T), estradiol (E) and FSH. The following parameters were assessed in the testis sections: diameter and length of seminiferous tubules (st), numbers of spermatogonia A + intermediate + B (A/In/B), preleptotene spermatocytes (PL), leptotene + zygotene + pachytene spermatocytes (L/Z/PA) and Sertoli cells per testis, percentage of st containing gonocytes or pachytene spermatocytes or lumen. An estrogenicity in vitro test was performed by means of a transgenic yeast strain expressing human estrogen receptor alpha. At both doses, DBP had no influence on testis and seminal vesicle weight, st diameter and length, number of germ and Sertoli cells per testis, percentage of st containing gonocytes or pachytene spermatocytes or lumen. DBP did not change E, T or FSH serum levels. The in vitro yeast screen showed that DBP was a weak estrogenic compound, approximately six to seven orders of magnitude less potent than 17β-estradiol. In conclusion, exposure of a rat to DBP in doses 100 or 1,000-fold higher than a Tolerable Daily Intake for humans had no effect on its testicular development. 相似文献
964.
Janusz Kościelniak Agnieszka Ostrowska Jolanta Biesaga-Kościelniak Władysław Filek Anna Janeczko Hazem Mohamed Kalaji Katarzyna Stalmach 《Acta Physiologiae Plantarum》2011,33(6):2329-2338
The effects of mycotoxin zearalenone (ZEN) on the photochemical activity of photosystem II (PSII) in wheat and soybean leaf
discs incubated in ZEN solutions as well as the after-effects of pre-sowing soaking of seeds in solutions containing ZEN on
the photochemical activity of PSII and on the seedlings growth under salt stress (NaCl solutions were investigated). The incubation
of wheat leaf discs in ZEN solutions strongly inhibited the energy flux per cross section (CS) for absorption (ABS/CS), trapping
(TRo/CS) and electron transport (ETo/CS), while the effects of ZEN action on soybean discs were opposite and the values of
those parameters significantly increased with the increase in ZEN concentration. Incubation of seeds in a ZEN solution resulted
in an increase in photochemical efficiency of PSII in soybean seedlings, but did not induce any response of PSII in those
of wheat at medium illuminations. Only at the stronger illumination for both species did ZEN induce an increase in efficiency
of excitation energy capture by open PSII reaction centers, photochemical quenching of chlorophyll a fluorescence and quantum yield of PSII electron transport. Pre-sowing soaking of seeds in a ZEN solution decreased the photoinhibitory
injuries of PSII in wheat and soybean due to safe scattering of the excess excitation energy through an increase in energy-dependent
quenching (qE) and state transition quenching (qT). ZEN when added to NaCl solutions during the period of germination contributed
to reduction in the growth inhibition of wheat seedlings. The incubation of wheat leaf discs in ZEN solutions strongly inhibited
CS, ABS/CS, TRo/CS and ETo/CS. Possible effects of ZEN on some physiological processes in plants have been discussed especially
in the context with photochemical activity of PSII and a salt stress. 相似文献
965.
966.
Wounded Medicago truncatula leaves produce a burst of O(2)(-) (phase I) between 1 and 15 min, then of O(2)(-) and H(2)O(2) (phase II) between 1 and 3 h. Our previous results suggest reactive oxygen species (ROS) may provide signals to mobilise early (6 h), apoplastic, wound-responsive proteins (WRPs). 2DE and MALDI-TOF/TOF were used to analyse how the suppression of ROS production at different time points by diphenyleneiodonium (DPI), affects the expression of WRPs. Rapid (≤3 min) DPI inhibition of phase I O(2)(-) production suppressed the differential regulation of 7 out of 19 WRPs, which were consequently classified as ROS-dependent WRPs. DPI inhibition of only phase II ROS production failed to suppress the wound regulation of 18 out of 19 WRPs, but led to the altered expression of 1 ROS-dependent WRP and 2 non-WRPs (Group B). The data indicates Group B proteins are alternatively targeted via the modulation of phase II ROS production. This reinforces an important role for phase I O(2)(-) signalling in the early wound response, but indicates that this response is partly regulated by phase II of the oxidative burst. This data provides an informed basis for further proteomic studies aimed at identifying early activated O(2)(-) signalling components in wounded Medicago. 相似文献
967.
Gonzalez-Bosquet J Calcei J Wei JS Garcia-Closas M Sherman ME Hewitt S Vockley J Lissowska J Yang HP Khan J Chanock S 《PloS one》2011,6(1):e14522
Identification of somatic mutations in cancer is a major goal for understanding and monitoring the events related to cancer initiation and progression. High resolution melting (HRM) curve analysis represents a fast, post-PCR high-throughput method for scanning somatic sequence alterations in target genes. The aim of this study was to assess the sensitivity and specificity of HRM analysis for tumor mutation screening in a range of tumor samples, which included 216 frozen pediatric small rounded blue-cell tumors as well as 180 paraffin-embedded tumors from breast, endometrial and ovarian cancers (60 of each). HRM analysis was performed in exons of the following candidate genes known to harbor established commonly observed mutations: PIK3CA, ERBB2, KRAS, TP53, EGFR, BRAF, GATA3, and FGFR3. Bi-directional sequencing analysis was used to determine the accuracy of the HRM analysis. For the 39 mutations observed in frozen samples, the sensitivity and specificity of HRM analysis were 97% and 87%, respectively. There were 67 mutation/variants in the paraffin-embedded samples, and the sensitivity and specificity for the HRM analysis were 88% and 80%, respectively. Paraffin-embedded samples require higher quantity of purified DNA for high performance. In summary, HRM analysis is a promising moderate-throughput screening test for mutations among known candidate genomic regions. Although the overall accuracy appears to be better in frozen specimens, somatic alterations were detected in DNA extracted from paraffin-embedded samples. 相似文献
968.
Sandegren L Groenheit R Koivula T Ghebremichael S Advani A Castro E Pennhag A Hoffner S Mazurek J Pawlowski A Kan B Bruchfeld J Melefors Ö Källenius G 《PloS one》2011,6(1):e16647
In molecular epidemiological studies of drug resistant Mycobacterium tuberculosis (TB) in Sweden a large outbreak of an isoniazid resistant strain was identified, involving 115 patients, mainly from the Horn of Africa. During the outbreak period, the genomic pattern of the outbreak strain has stayed virtually unchanged with regard to drug resistance, IS6110 restriction fragment length polymorphism and spoligotyping patterns. Here we present the complete genome sequence analyses of the index isolate and two isolates sampled nine years after the index case as well as experimental data on the virulence of this outbreak strain. Even though the strain has been present in the community for nine years and passaged between patients at least five times in-between the isolates, we only found four single nucleotide polymorphisms in one of the later isolates and a small (4 amino acids) deletion in the other compared to the index isolate. In contrast to many other evolutionarily successful outbreak lineages (e.g. the Beijing lineage) this outbreak strain appears to be genetically very stable yet evolutionarily successful in a low endemic country such as Sweden. These findings further illustrate that the rate of genomic variation in TB can be highly strain dependent, something that can have important implications for epidemiological studies as well as development of resistance. 相似文献
969.
Lurie G Gaudet MM Spurdle AB Carney ME Wilkens LR Yang HP Weiss NS Webb PM Thompson PJ Terada K Setiawan VW Rebbeck TR Prescott J Orlow I O'Mara T Olson SH Narod SA Matsuno RK Lissowska J Liang X Levine DA Le Marchand L Kolonel LN Henderson BE Garcia-Closas M Doherty JA De Vivo I Chen C Brinton LA Akbari MR;Australian National Endometrial Cancer Study Group;Epidemiology of Endometrial Cancer Consortium 《PloS one》2011,6(2):e16756
Overweight and obesity are strongly associated with endometrial cancer. Several independent genome-wide association studies recently identified two common polymorphisms, FTO rs9939609 and MC4R rs17782313, that are linked to increased body weight and obesity. We examined the association of FTO rs9939609 and MC4R rs17782313 with endometrial cancer risk in a pooled analysis of nine case-control studies within the Epidemiology of Endometrial Cancer Consortium (E2C2). This analysis included 3601 non-Hispanic white women with histologically-confirmed endometrial carcinoma and 5275 frequency-matched controls. Unconditional logistic regression models were used to assess the relation of FTO rs9939609 and MC4R rs17782313 genotypes to the risk of endometrial cancer. Among control women, both the FTO rs9939609 A and MC4R rs17782313 C alleles were associated with a 16% increased risk of being overweight (p = 0.001 and p = 0.004, respectively). In case-control analyses, carriers of the FTO rs9939609 AA genotype were at increased risk of endometrial carcinoma compared to women with the TT genotype [odds ratio (OR) = 1.17; 95% confidence interval (CI): 1.03–1.32, p = 0.01]. However, this association was no longer apparent after adjusting for body mass index (BMI), suggesting mediation of the gene-disease effect through body weight. The MC4R rs17782313 polymorphism was not related to endometrial cancer risk (per allele OR = 0.98; 95% CI: 0.91–1.06; p = 0.68). FTO rs9939609 is a susceptibility marker for white non-Hispanic women at higher risk of endometrial cancer. Although FTO rs9939609 alone might have limited clinical or public health significance for identifying women at high risk for endometrial cancer beyond that of excess body weight, further investigation of obesity-related genetic markers might help to identify the pathways that influence endometrial carcinogenesis. 相似文献
970.
Jolanta Zanelli Kevin Morgan Paola Dazzan Craig Morgan Manuela Russo Izabela Pilecka Paul Fearon Arsime Demjaha Gill A. Doody Peter B. Jones Robin M. Murray Abraham Reichenberg 《PloS one》2013,8(10)