全文获取类型
收费全文 | 209篇 |
免费 | 18篇 |
国内免费 | 1篇 |
出版年
2020年 | 3篇 |
2018年 | 2篇 |
2017年 | 2篇 |
2016年 | 4篇 |
2015年 | 10篇 |
2014年 | 9篇 |
2013年 | 14篇 |
2012年 | 15篇 |
2011年 | 16篇 |
2010年 | 10篇 |
2009年 | 11篇 |
2008年 | 4篇 |
2007年 | 9篇 |
2006年 | 6篇 |
2005年 | 4篇 |
2004年 | 3篇 |
2003年 | 7篇 |
2002年 | 5篇 |
2001年 | 1篇 |
2000年 | 3篇 |
1999年 | 6篇 |
1998年 | 9篇 |
1997年 | 5篇 |
1996年 | 5篇 |
1995年 | 1篇 |
1994年 | 6篇 |
1993年 | 3篇 |
1992年 | 5篇 |
1991年 | 6篇 |
1990年 | 2篇 |
1989年 | 4篇 |
1988年 | 4篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1984年 | 1篇 |
1983年 | 4篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1970年 | 1篇 |
1964年 | 1篇 |
1960年 | 1篇 |
1936年 | 2篇 |
1932年 | 1篇 |
1914年 | 2篇 |
1912年 | 4篇 |
排序方式: 共有228条查询结果,搜索用时 15 毫秒
11.
Isidrogalvia longiflora, a new combination based onAsagraea longiflora, is proposed. It is the first record ofIsidrogalvia from Bolivia. 相似文献
12.
Laurence J. Dorr 《Brittonia》1992,44(1):53-13
In 1843 S. B. Buckley (1809–1884) traveled up the St. Johns River, Florida in search of plants, shells, and possibly other
natural history objects. Buckley encountered many difficulties in interior Florida and his trip did not live up to his original
expectations. It was unfortunate that the took years to distribute his plant specimens, since few botanists or naturalists
had preceded him into that poorly explored region. 相似文献
13.
Laurence J. Dorr 《Brittonia》1992,44(1):1-13
In 1843 S. B. Buckley (1809–1884) traveled up the St. Johns River, Florida in search of plants, shells, and possibly other natural history objects. Buckley encountered many difficulties in interior Florida and his trip did not live up to his original expectations. It was unfortunate that the took years to distribute his plant specimens, since few botanists or naturalists had preceded him into that poorly explored region. 相似文献
14.
The K+/H+ antiporter LeNHX2 increases salt tolerance by improving K+ homeostasis in transgenic tomato 总被引:1,自引:0,他引:1
RAÚL HUERTAS LOURDES RUBIO OLIVIER CAGNAC MARÍA JESÚS GARCÍA‐SÁNCHEZ JUAN DE DIOS ALCHÉ KEES VENEMA JOSÉ ANTONIO FERNÁNDEZ MARÍA PILAR RODRÍGUEZ‐ROSALES 《Plant, cell & environment》2013,36(12):2135-2149
The endosomal LeNHX2 ion transporter exchanges H+ with K+ and, to lesser extent, Na+. Here, we investigated the response to NaCl supply and K+ deprivation in transgenic tomato (Solanum lycopersicum L.) overexpressing LeNHX2 and show that transformed tomato plants grew better in saline conditions than untransformed controls, whereas in the absence of K+ the opposite was found. Analysis of mineral composition showed a higher K+ content in roots, shoots and xylem sap of transgenic plants and no differences in Na+ content between transgenic and untransformed plants grown either in the presence or the absence of 120 mm NaCl. Transgenic plants showed higher Na+/H+ and, above all, K+/H+ transport activity in root intracellular membrane vesicles. Under K+ limiting conditions, transgenic plants enhanced root expression of the high‐affinity K+ uptake system HAK5 compared to untransformed controls. Furthermore, tomato overexpressing LeNHX2 showed twofold higher K+ depletion rates and half cytosolic K+ activity than untransformed controls. Under NaCl stress, transgenic plants showed higher uptake velocity for K+ and lower cytosolic K+ activity than untransformed plants. These results indicate the fundamental role of K+ homeostasis in the better performance of LeNHX2 overexpressing tomato under NaCl stress. 相似文献
15.
16.
Germination,Viability and Clearance of Stachybotrys chartarum in the Lungs of Infant Rats 总被引:1,自引:0,他引:1
Observing that the conidia of Stachybotrys chartarum can germinate in the lung of infant rats, it became important to ascertain whether an infection can ensue. Viable conidia of S. chartarum were instilled into the lungs of 4 and 14 day-old rat pups. Germination was observed frequently in the lungs of 4 day-old but rarely in the 14 day-old pups. In the 4 day-old pups, pulmonary inflammation with hemorrhagic exudates was observed and resulted in about 15% mortality rate compared to 0% for the controls instilled with phosphate buffered saline. Acute neutrophilic inflammation and intense interstitial pneumonia with poorly formed granulomas observed three days following exposure were associated with fungal hyphae and conidia. The surviving experimental pups showed significantly slower weight gain for seven days. Dilution plating and quantitative PCR analysis were used to follow total fungal load in the rat pups lung homogenates. In the 4 day-old rat pups viable fungi decreased rapidly and were less than 1% by day seven. Similarly, fungal DNA decreased exponentially and was only 0.03% by fourteen days after exposure. However, 14 day-old rat pups showed neither the lethal effects of exposures to viable conidia of S. chartarum nor the slower weight gain, and the fungal load decreased even more rapidly. We conclude that S. chartarum conidia can initially germinate and form hyphae but even in the immature rat pups do not establish an effective infection, although a very limited persistence cannot be excluded.This revised version was published online in October 2005 with corrections to the Cover Date. 相似文献
17.
Volume changes were studied in Beta vulgaris storage root vacuoles, using video microscopy, when exposed to hypotonic conditions. The osmotic gradient was either step-applied or progressively imposed in perfusion experiments. Preincubation at low pH (6.6) or with HgCl2 strongly reduced the vacuoles' water permeability, measured in step experiments. Furthermore, the volumetric response depended on the rate with which the aniso-osmotic condition was established. In perfusion experiments a "plateau value" (osmotic equilibrium or steady-state volume value) was observed, which was significantly lower than the theoretically expected one. Furthermore, if vacuoles were preincubated in presence of HgCl2 or at low pH and then the hypo-osmotic challenge was applied in perfusion experiments, a still lower "plateau value" was observed. This reduction was concentration-dependent and completely reversible. In these conditions, when HgCl2 concentration was 300 mM or medium pH was 6.6, the volume change was abolished. In other experiments, when urea iso-osmotically replaced mannitol, a reversible, pH-dependent volumetric response was observed. These results can be interpreted accepting that 1) mercury-sensitive water channels, present in the studied structure, were blocked by low pH during the hypo-osmotic challenge; 2) modification of water permeability prevents excessive swelling during the osmotic shock; 3) the effectiveness of this last mechanism depended on the osmotic challenge rate; and 4) additionally, urea reflection coefficients were also modified by reduced medium pH. 相似文献
18.
19.
Yike I Miller MJ Sorenson WG Walenga R Tomashefski JF Dearborn DG 《Mycopathologia》2002,154(3):139-152
In recent years cases of often fatal pulmonary hemorrhage in infants have been associated with water damaged homes and the
toxigenic fungusStachybotrys chartarum. The fungal spores contain mycotoxins which could be injurious to the rapidly developing lung. In order to understand the
developmental pathophysiology of this disease we developed an infant rat model of stachybotrytoxicosis describing the effects
of fungal spores on survival, growth, histopathology of the lung and respiration. Conidia ofS. chartarum were instilled intratracheally (1.0–8.0 × 105/gm wt.) in 4-dold Sprague-Dawley rat pups. Two control groups received either sterile PBS or a suspension of spores extensively
extracted with ethanol to remove toxins. Lethal dose response was determined (LD50 = 2.7 × 105 spores/gm wt.). All dead pups had extensively hemorrhagic lungs. Growth of surviving animals was impaired in a dose-dependent
manner. Changes of pulmonary function parameters in rats treated with 1.1 × 105 spores/g were consistent with an increased respiratory resistance. Histology of lungs revealed fresh hemorrhage, sparse hemosiderin-laden
macrophages, and evidence of inflammation including thickened alveolar septa infiltrated by lymphocytes and mononuclear cells
and intra-alveolar macrophages. Significant increases (p = 0.001) in numbers of macrophages (2-fold), lymphocytes (5-fold)
and neutrophils (7-fold) were found in BAL fluid. Hemoglobin was elevated 2-fold (p = 0.004). Proinflammatory mediator IL-1β
increased more than 6-fold and TNF-α30-fold (p = 0.001). Extracted spores had a minimal effect on all examined parameters
in BAL fluid indicating that mycotoxins are primarily responsible for the hemorrhagic and inflammatory response.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
20.
Phylogenetic utility of the nuclear gene arginine decarboxylase: an example from Brassicaceae 总被引:10,自引:2,他引:8
Arginine decarboxylase (ADC) is an important enzyme in the production of
putrescine and polyamines in plants. It is encoded by a single or low-copy
nuclear gene that lacks introns in sequences studied to date. The rate of
Adc amino acid sequence evolution is similar to that of ndhF for the
angiosperm family studied. Highly conserved regions provide several target
sites for PCR priming and sequencing and aid in nucleotide and amino acid
sequence alignment across a range of taxonomic levels, while a variable
region provides an increased number of potentially informative characters
relative to ndhF for the taxa surveyed. The utility of the Adc gene in
plant molecular systematic studies is demonstrated by analysis of its
partial nucleotide sequences obtained from 13 representatives of
Brassicaceae and 3 outgroup taxa, 2 from the mustard oil clade (order
Capparales) and 1 from the related order Malvales. Two copies of the Adc
gene, Adc1 and Adc2, are found in all members of the Brassicaceae studied
to data except the basal genus Aethionema. The resulting Adc gene tree
provides robust phylogenetic data regarding relationships within the
complex mustard family, as well as independent support for proposed tribal
realignments based on other molecular data sets such as those from
chloroplast DNA.
相似文献