全文获取类型
收费全文 | 216篇 |
免费 | 22篇 |
出版年
2023年 | 1篇 |
2022年 | 1篇 |
2021年 | 4篇 |
2020年 | 7篇 |
2019年 | 4篇 |
2018年 | 3篇 |
2017年 | 6篇 |
2016年 | 7篇 |
2015年 | 6篇 |
2014年 | 10篇 |
2013年 | 17篇 |
2012年 | 18篇 |
2011年 | 10篇 |
2010年 | 7篇 |
2009年 | 13篇 |
2008年 | 5篇 |
2007年 | 15篇 |
2006年 | 9篇 |
2005年 | 10篇 |
2004年 | 10篇 |
2003年 | 6篇 |
2002年 | 6篇 |
2001年 | 4篇 |
2000年 | 3篇 |
1999年 | 3篇 |
1998年 | 6篇 |
1997年 | 1篇 |
1996年 | 4篇 |
1995年 | 3篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1992年 | 3篇 |
1991年 | 4篇 |
1989年 | 4篇 |
1987年 | 1篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1983年 | 6篇 |
1982年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1975年 | 1篇 |
1974年 | 2篇 |
1971年 | 1篇 |
1969年 | 1篇 |
1917年 | 1篇 |
排序方式: 共有238条查询结果,搜索用时 31 毫秒
101.
BACKGROUND: Pulmonary tumorlets are usually an incidental pathologic curiosity of no clinical importance, but may be mistaken for epithelial and nonepithelial neoplasms. Fine needle aspiration (FNA) of this cell proliferation has rarely been reported. We describe a pulmonary tumorlet associated with bronchocentric granulomatosis presenting as a tumorous consolidation on chest radiograph. CASE: In a hitherto healthy 70-year-old man admitted for acute respiratory infection, a solid consolidation was found on chest radiograph. Medical history was uneventful except right-sided pleurisy in 1949. Computed tomography-guided FNA sample was composed of loose clusters of small columnar cells with cyanophilic cytoplasm and centrally located round to oval nuclei. With a tentative diagnosis of well-differentiated adenocarcinoma, lumpectomy was performed. Intraoperative cytology demonstrated lymphocytes, epithelioid cells, giant cells of Langerhans type and clusters of columnar cells. Definitive histologic examination confirmed the intraoperative diagnosis of necrotizing granulomatosis and tumorlet. Neuroendocrine origin of the cells was confirmed by immunocytochemical and immunohistochemical studies resulting in strong reactivity of the cells to synaptophysin, NSE, chromogranin A and N-Cam. CONCLUSION: Knowledge of the cytomorphologic presentation of tumorlets in FNA and consideration of the appropriate differential diagnoses combined with ancillary studies might have prevented lung resection. 相似文献
102.
Six novel polymorphic microsatellite loci are presented for the grass snake (Natrix natrix), a species with declining populations in many regions. The number of alleles per locus ranged from two to seven. Four dice snake (Natrix tessellata) microsatellites were polymorphic in the grass snake with three to four alleles. At two loci, the expected heterozygosity differed significantly from observed heterozygosity. Cross-amplification of the grass snake markers in the dice snake showed two polymorphic microsatellites with two and four alleles. 相似文献
103.
This study presents data on over 350,000 insured Swedish dogs up to 10 years of age contributing to over one million dog-years
at risk (DYAR) during 1995–2000. A total of 43,172 dogs died or were euthanised and of these 72% had a claim with a diagnosis
for the cause of death. The overall total mortality was 393 deaths per 10,000 DYAR. Mortality rates are calculated for the
10 most common breeds, 10 breeds with high mortality and a group including all other breeds, crudely and for general causes
of death. Proportional mortality is presented for several classifications. Five general causes accounted for 62% of the deaths
with a diagnosis (i.e. tumour (18%), trauma (17%), locomotor (13%), heart (8%) and neurological (6%)). Mortality rates for
the five most common diagnoses within the general causes of death are presented. These detailed statistics on mortality can
be used in breed-specific strategies as well as for general health promotion programs. Further details on survival and relative
risk by breed and age are presented in the companion paper [14]. 相似文献
104.
Heme-Dependent Rubber Oxygenase RoxA of Xanthomonas sp. Cleaves the Carbon Backbone of Poly(cis-1,4-Isoprene) by a Dioxygenase Mechanism
下载免费PDF全文
![点击此处可从《Applied microbiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Oxidative cleavage of poly(cis-1,4-isoprene) by rubber oxygenase RoxA purified from Xanthomonas sp. was investigated in the presence of different combinations of 16O2, 18O2, H216O, and H218O. 12-Oxo-4,8-dimethyl-trideca-4,8-diene-1-al (ODTD; m/z 236) was the main cleavage product in the absence of 18O-compounds. Incorporation of one 18O atom in ODTD was found if the cleavage reaction was performed in the presence of 18O2 and H216O. Incubation of poly(cis-1,4-isoprene) (with RoxA) or of isolated unlabeled ODTD (without RoxA) with H218O in the presence of 16O2 indicated that the carbonyl oxygen atoms of ODTD significantly exchanged with oxygen atoms derived from water. The isotope exchange was avoided by simultaneous enzymatic reduction of both carbonyl functions of ODTD to the corresponding dialcohol (12-hydroxy-4,8-dimethyl-trideca-4,8-diene-1-ol (HDTD; m/z 240) during RoxA-mediated in vitro cleavage of poly(cis-1,4-isoprene). In the presence of 18O2, H216O, and alcohol dehydrogenase/NADH, incorporation of two atoms of 18O into the reduced metabolite HDTD was found (m/z 244), revealing that RoxA cleaves rubber by a dioxygenase mechanism. Based on the labeling results and the presence of two hemes in RoxA, a model of the enzymatic cleavage mechanism of poly(cis-1,4-isoprene) is proposed. 相似文献
105.
Novel microsatellite markers for Dalechampia scandens (Euphorbiaceae) and closely related taxa: application to studying a species complex
下载免费PDF全文
![点击此处可从《Plant Species Biology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Mohsen Falahati‐Anbaran Hans K. Stenøien Geir H. Bolstad Thomas F. Hansen Rocío Pérez‐Barrales W Scott Armbruster Christophe Pélabon 《Plant Species Biology》2017,32(2):179-186
We developed novel microsatellite markers for D alechampia scandens L. (Euphorbiaceae). The target plants belong to a distinct, but undescribed, species in the D . scandens species complex, characterized by small resin‐producing glands. In total, 110 alleles over 36 novel markers were identified across 39 individuals from three populations. The number of alleles varied from one to seven, with an average of 3.06 ± 0.26 alleles per locus. The developed markers, along with previously developed ones for a large‐glanded D . scandens species, were tested for amplification in 11 additional species of the genus D alechampia. Four markers did not produce any detectable allele in 37 individuals from two populations of the large‐glanded species. Average expected heterozygosity across all small‐ and large‐glanded specific loci was 0.36 and 0.15, for the small and large glanded populations, respectively. Cross‐species amplification showed that 89% of all markers were successfully amplified in at least one of the 11 other D alechampia species. These microsatellite markers may be useful for detecting undescribed species in the D . scandens species complex, and can be used for comparative analyses of genetic structure, mating system and phylogeography of other D alechampia species. 相似文献
106.
Isolation and identification of N-mercapto-4-formylcarbostyril, an antibiotic produced by Pseudomonas fluorescens. 总被引:2,自引:0,他引:2
Pseudomonas fluorescens strain G308 isolated from barley leaves produces a novel antibiotic substance that was purified by preparative TLC and HPLC and identified as N-mercapto-4-formylcarbostyril (Cbs) by LC/DAD, IR, LC-ES(+)/MS, LC-ES(-)/MS, GC-EI/MS, LC-HRES(+)/MS, mass isotope ratios analysis, 1H NMR and 13C NMR analysis. The purified new antibiotic compound is effective against many phytopathogenic fungi in vitro. The compound inhibited at 25 ppm spore germination and germ tube growth of the following fungi; Fusarium oxysporum f. sp. lycopersici, Fusarium culmorum, Cladosporium cucumerinum and Colletotrichum lagenarium. At concentrations up to 125 ppm, the compound did not interfere with release of zoospores from sporangia and germination of encysted zoospores of Phytophthora infestans. 相似文献
107.
Plasma levels and cardiovascular gene expression of urotensin-II in human heart failure 总被引:3,自引:0,他引:3
Dschietzig T Bartsch C Pregla R Zurbrügg HR Armbruster FP Richter C Laule M Romeyke E Neubert C Voelter W Baumann G Stangl K 《Regulatory peptides》2002,110(1):33-38
The peptide urotensin-II (U-II) has been described as most potent vasoconstrictor identified so far, but plasma values in humans and its role in cardiovascular pathophysiology are unknown. We investigated circulating urotensin-II and its potential role in human congestive heart failure (CHF). We enrolled control individuals (n=13; cardiac index [CI], 3.5+/-0.1 l/min/m2; pulmonary wedge pressure [PCWP], 10+/-1 mm Hg), patients with moderate (n=10; CI, 2.9+/-0.3 l/min/m2; PCWP, 14+/-2 mm Hg) and severe CHF (n=11; CI, 1.8+/-0.2 l/min/m2; PCWP, 33+/-2 mm Hg). Plasma levels of urotensin-II differed neither between controls, patients with moderate and severe CHF nor between different sites of measurement (pulmonary artery, left ventricle, coronary sinus, antecubital vein) within the single groups. Hemodynamic improvement by vasodilator therapy in severe CHF (CI, +78+/-3%; PCWP, -55+/-3%) did not affect circulating U-II over 24 h. Preprourotensin-II mRNA expression in right atria, left ventricles, mammary arteries and saphenous veins did not differ between controls with normal heart function and patients with end-stage CHF. In conclusion, urotensin-II plasma levels and its myocardial and vascular gene expression are unchanged in human CHF. Circulating urotensin-II does not respond to acute hemodynamic improvement. These findings suggest that urotensin-II does not play a major role in human CHF. 相似文献
108.
Sexual antagonism in the pistil varies among populations of a hermaphroditic mixed‐mating plant
下载免费PDF全文
![点击此处可从《Journal of evolutionary biology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
E. Hersh J. A. Madjidian S. Andersson M. Strandh W. S. Armbruster Å. Lankinen 《Journal of evolutionary biology》2015,28(7):1321-1334
Sexual conflicts and their evolutionary outcomes may be influenced by population‐specific features such as mating system and ecological context; however, very few studies have investigated the link between sexual conflict and mating system. The self‐compatible, mixed‐mating hermaphrodite Collinsia heterophylla (Plantaginaceae) is thought to exhibit a sexual conflict over timing of stigma receptivity. This conflict involves (i) delayed stigma receptivity, which intensifies pollen competition, and (ii) early fertilization forced by pollen, which reduces seed set. We investigated the potential for the conflict to occur under field conditions and performed glasshouse crosses within eight populations to assess its consistency across populations. Flowers were visited, and produced seeds after pollination, at all developmental stages, suggesting that the conflict can be of significance under natural conditions. In the glasshouse, early pollination imposed costs in all populations. Overall, the timing of first seed set was most strongly affected by the maternal parent, denoting stronger female than male ability to influence the onset of stigma receptivity. Crosses also revealed a negative relationship between donor‐ and recipient‐related onset of receptivity within individuals, a novel result hinting at trade‐offs in sex allocation or a history of antagonistic selection. Neither timing of stigma receptivity, timing of first seed set, nor pollen competitive ability covaried with population outcrossing rate. In conclusion, these results indicate that sexually antagonistic selection may be present in varying degrees in different populations of C. heterophylla, but this variation does not appear to be directly related to mating system variation. 相似文献
109.
Recent nuclear transfer of organellar DNA is thought to result mainly in nonfunctional nuclear sequences or in genetic dysfunction. Here we show that nuclear exons encoding novel protein sequences can be generated by insertions of organellar DNA. Most of the protein sequences do not correspond to preexisting organellar coding sequences or they represent markedly reshaped protein domains, reflecting the recruitment and adaptation of encoded proteins to new functions. Organelle-derived DNA insertions might be responsible for many more ancient functional exon acquisitions that are not directly detectable. 相似文献
110.
The production of β-glucuronidase (GUS) driven by the Arabidopsis small heat shock protein 18.2 promoter in liquid cultures of transgenic tobacco (Nicotiana tabacum) hairy roots is reported. Clone GD-3, showing high GUS heat induction and a moderate growth rate, was selected from 436 clones
for study. Treatment of GD-3 with heat shock at 36–42°C for 2 h then recovery at 27°C resulted in an increase in GUS specific
activity, while higher heat-shock temperatures led to a decline. These results were in accordance with the change in esterase
activity, a measure of tissue viability. Using 2 h of 42°C heat shock and a recovery phase at 27°C, GUS specific activity
increased rapidly and reached a maximum of 267.6 nmol 4-methylumbelliferyl β-D-glucuronic acid (MU) min−1 mg−1 protein at 24 h of recovery. When tissues were continuously heated at 42°C and tested without a recovery period, GUS mRNA
was detectable at 2 h and peaked at 5 h, but GUS activity was not seen until 10 h and did not peak until 28 h; in addition,
the maximum activity was lower than that seen after heat shock for only 30 min or 2 h, followed by recovery. This shows that
recovery at normal temperature is crucial for the heat-inducible heterogeneous expression system of transgenic hairy roots.
Multiple heat-shock treatments showed that this system was heat reinducible, although a gradual decline in GUS specific activity
was seen in the second and third cycles. 相似文献