全文获取类型
收费全文 | 251篇 |
免费 | 19篇 |
专业分类
270篇 |
出版年
2022年 | 3篇 |
2021年 | 4篇 |
2020年 | 2篇 |
2019年 | 6篇 |
2018年 | 4篇 |
2017年 | 4篇 |
2016年 | 3篇 |
2015年 | 6篇 |
2014年 | 14篇 |
2013年 | 20篇 |
2012年 | 20篇 |
2011年 | 27篇 |
2010年 | 7篇 |
2009年 | 10篇 |
2008年 | 20篇 |
2007年 | 17篇 |
2006年 | 15篇 |
2005年 | 15篇 |
2004年 | 8篇 |
2003年 | 10篇 |
2002年 | 9篇 |
2001年 | 1篇 |
2000年 | 1篇 |
1999年 | 3篇 |
1998年 | 3篇 |
1997年 | 4篇 |
1996年 | 1篇 |
1995年 | 3篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1985年 | 2篇 |
1984年 | 4篇 |
1982年 | 2篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1967年 | 2篇 |
1966年 | 1篇 |
1965年 | 1篇 |
1962年 | 1篇 |
1961年 | 1篇 |
1960年 | 2篇 |
1959年 | 1篇 |
1958年 | 1篇 |
排序方式: 共有270条查询结果,搜索用时 15 毫秒
61.
OBJECTIVE: To evaluate the efficacy of immunocytochemistry (ICC) performed on smears processed by thin-layer cytology (TLC). STUDY DESIGN: During the period January 2001-September 2003, 3,573 consecutive fine needle aspiration biopsies were processed with both conventional smears (CSs) and TLC diagnosed by a single pathologist; 113 required immunocytochemical study. CSs were fixed in ethanol whereas TLC slides were processed with the ThinPrep 2000 method (Cytyc Co., Marlborough, Massachusetts, U.S.A); both were stained with Papanicolaou stain. ICC staining was carried out on only TLC slides. RESULTS: The 113 cytologic cases were grouped as follows: 32 thyroid nodules with 16 histologic controls (HCs), 24 lymph nodes (regardless of location) with 15 HCs, 18 liver and pancreatic lesions (3 HCs), 11 lung nodules (6 HCs), 5 kidney and adrenal gland lesions (1 HC), 6 abdominal (2 HCs) and 4 mediastinal masses (1 HC), 6 salivary gland tumors (3 HCs), 4 bone masses (2 HCs) and 3 subcutaneous lesions (1 HC). ICC contributed to the diagnosis in 104 cases (92%), whereas it was inconclusive in 9. The cytologic diagnoses were histologically confirmed in 46 of 50 cases (92%). CONCLUSION: ICC can be successfully applied on TLC slides with better results than on CSs, and its yield can be useful in making the correct diagnosis on fine needle aspiration biopsy. 相似文献
62.
Alvaro Foieri Eduardo Gabriel Virla Arnaldo Maciá Ana Maria Marino de Remes Lenicov 《Entomologia Experimentalis et Applicata》2020,168(8):618-625
Among the species belonging to 11 genera of Neotropical spittlebugs attacking graminaceous plants, Notozulia entreriana (Berg) (Hemiptera: Cercopidae) is one of the most important pests of grasses in several countries of South America. In this study, we evaluate the influence of three economically relevant species of host plants (Poaceae) on life-cycle traits of N. entreriana. We tested for differences in fitness responses (survival and fecundity) of insects on forage species which are frequent hosts for wild populations of spittlebugs. Comparison of life cycles on three host plants showed that only 2.5% of nymphs completed their development on Zea mays L., 22.5% on Chloris gayana Kunth, and 95% on Brachiaria decumbens Stapf. All the above suggests that C. gayana and B. decumbens are able to sustain complete development, behaving like natural hosts; the latter species is superior for artificial colonies because a shorter developmental period, higher survivorship in nymphs, and longer lifespan of adults were observed. Zea mays did not allow proper development, causing high mortality instead. We also developed a new approach for small-scale breeding of N. entreriana, which will enable subsequent biological and behavioral studies on this important pest species. 相似文献
63.
Yao Z Li P Zhang Q Schwarz EM Keng P Arbini A Boyce BF Xing L 《The Journal of biological chemistry》2006,281(17):11846-11855
Osteoclasts are essential cells for bone erosion in inflammatory arthritis and are derived from cells in the myeloid lineage. Recently, we reported that tumor necrosis factor-alpha (TNFalpha) increases the blood osteoclast precursor (OCP) numbers in arthritic patients and animals, which are reduced by anti-TNF therapy, implying that circulating OCPs may have an important role in the pathogenesis of erosive arthritis. The aim of this study is to investigate the mechanism by which TNFalpha induces this increase in OCP frequency. We found that TNFalpha stimulated cell division and conversion of CD11b+/Gr-1-/lo/c-Fms- to CD11b+/Gr-1-/lo/c-Fms+ cells, which was not blocked by neutralizing macrophage colony-stimulating factor (M-CSF) antibody. Ex vivo analysis of monocytes demonstrated the following: (i) blood CD11b+/Gr-1-/lo but not CD11b-/Gr-1- cells give rise to osteoclasts when they were cultured with receptor activator NF-kappaB ligand and M-CSF; and (ii) TNF-transgenic mice have a significant increase in blood CD11b+/Gr-1-/lo cells and bone marrow proliferating CD11b+/Gr-1-/lo cells. Administration of TNFalpha to wild type mice induced bone marrow CD11b+/Gr-1-/lo cell proliferation, which was associated with an increase in CD11b+/Gr-1-/lo OCPs in the circulation. Thus, TNFalpha directly stimulates bone marrow OCP genesis by enhancing c-Fms expression. This results in progenitor cell proliferation and differentiation in response to M-CSF, leading to an enlargement of the marrow OCP pool. Increased marrow OCPs subsequently egress to the circulation, forming a basis for elevated OCP frequency. Therefore, the first step of TNF-induced osteoclastogenesis is at the level of OCP genesis in the bone marrow, which represents another layer of regulation to control erosive disease. 相似文献
64.
Godoy P Tiraboschi IN Severo LC Bustamante B Calvo B Almeida LP da Matta DA Colombo AL 《Memórias do Instituto Oswaldo Cruz》2003,98(3):401-405
From March 1999 to March 2000, we conducted a prospective multicenter study of candidemia involving five tertiary care hospitals from four countries in Latin America. Yeast isolates were identified by classical methods and the antifungal susceptibility profile was determined according to the National Committee for Clinical Laboratory Standards microbroth assay method. During a 12 month-period we were able to collect a total of 103 bloodstream isolates of Candida spp. C. albicans was the most frequently isolated species accounting for 42% of all isolates. Non-albicans Candida species strains accounted for 58% of all episodes of candidemia and were mostly represented by C. tropicalis (24.2%) and C. parapsilosis (21.3%). It is noteworthy that we were able to identify two cases of C. lusitaniae from different institutions. In our casuistic, non-albicans Candida species isolates related to candidemic episodes were susceptible to fluconazole. Continuously surveillance programs are needed in order to identify possible changes in the species distribution and antifungal susceptibility patterns of yeasts that may occurs after increasing the use of azoles in Latin American hospitals. 相似文献
65.
Volatile constituents of Aristolochia argentina 总被引:1,自引:0,他引:1
The essential oils from leaves, aerial stems and underground organs of Aristolochia argentina Gris., a medicinal plant popularly known as "charrúa", were obtained by hydrodistillation and analyzed by GC and GC/MS. Forty-three components were identified in the oils. All parts of the plant afforded volatile oils characterized by high levels of argentilactone (57-89%) and the presence of undecatriene isomers (0.3-4.0%), these latter compounds providing the essential oils and extracts with an intense particular odor. Terpenes account for the remaining portion of the essential oils (5-29%). Bicyclogermacrene predominates in the aerial parts of the plant, whereas ishwarane is the main terpene of the subterranean organs. Argentilactone, a suspected carcinogenic compound, was also identified in a medicinal commercial tincture of A. argentina. 相似文献
66.
Lung cancer identification by the analysis of breath by means of an array of non-selective gas sensors 总被引:5,自引:0,他引:5
Di Natale C Macagnano A Martinelli E Paolesse R D'Arcangelo G Roscioni C Finazzi-Agrò A D'Amico A 《Biosensors & bioelectronics》2003,18(10):1209-1218
Previous finding shown that the composition of the breath of patients with lung cancer contains information that could be used to detect the disease. These volatiles are mainly alkanes and aromatic compounds. Sensor arrays technology (electronic nose) proved to be useful to screen samples characterised by different headspace composition. Here we investigated the possibility of using an electronic nose to check whether volatile compounds present in expired air may diagnose lung cancer. Breath samples were collected and immediately analysed by an electronic nose. A total of 60 individuals were involved in the experiment. 35 of them were affected by lung cancer, 18 individuals were measured as reference and nine were measured after the surgical therapy. Two individuals were measured twice, before and after the surgical therapy, for a total of 62 measurements. An electronic nose, composed by eight quartz microbalance (QMB) gas sensors, coated with different metalloporphyrins, was used. These sensors show a good sensitivity towards those compounds previously indicated as possible lung cancer markers in breath. The application of a 'partial least squares-discriminant analysis' (PLS-DA) found out a 100% of classification of lung cancer affected patients, 94% of reference was correctly classified. The class of post-surgery patients were correctly individuated in 44% of the cases, while the other samples were classified as healthy references. The alteration of breath composition induced by the presence of lung cancer was enough to allow a complete identification of the sample of diseased individuals. Extended studies are necessary to evaluate the resolution of the method, namely the stage at which the disease may be identified in order to use this instrument for early diagnosis. 相似文献
67.
Nestin expression in rat adrenal gland 总被引:2,自引:1,他引:1
Bertelli E Regoli M Lucattelli M Bastianini A Fonzi L 《Histochemistry and cell biology》2002,117(4):371-377
The constituents of the intermediate filament network of adrenal gland cells have not been deeply investigated in vivo. Adrenocortical cells have been reported to express cytokeratins and vimentin, but the intermediate filament components of the adrenomedullary cells are still unknown. Nestin is an intermediate filament protein that is mainly expressed in the developing nervous and muscle systems. It has been reported to be unable to form filaments by itself and it co-assembles with vimentin. Using immunocytochemical and biochemical approaches, the present study demonstrates that nestin is expressed in situ either in the cortex or in the medulla of adult rat adrenal glands. Nestin-negative cells prevalently form the zona glomerulosa whereas the zona fasciculata and the zona reticularis are mainly nestin-immunoreactive. Nestin-positive cells always express vimentin-like immunoreactivity but several cells apparently expressing only vimentin are detectable too. Nestin is also expressed by adrenomedullary cells that also display a faint vimentin-like immunoreactivity. We hypothesise that the inconstant detection of nestin in adrenocortical cells depends on their different functional moments. Moreover, even though our data do not allow to confirm vimentin in adrenomedullary cells, in situ detection of nestin in the adrenal medulla indirectly supports in vivo expression of vimentin in chromaffin cells. 相似文献
68.
Nucci Marcio Silveira Maria Isabel Spector Nelson Silveira Fernanda Velasco Eduardo Martins Carlos Alberto Derossi Andrea Colombo Arnaldo L. Pulcheri Wolmar 《Mycopathologia》1998,141(2):65-68
The objective of this study was to characterize the epidemiology of candidemia in cancer patients in the city of Rio de Janeiro,
Brazil. An 18-month survey of fungemia in patients with cancer was undertaken in three Hospitals in Rio de Janeiro. Forty-three
episodes of candidemia were identified in 43 patients, 43 of which were episodes of candidemia; in ten cases the strains were
not available for further identification of species and were excluded from this analysis. The overall distribution of fungi
causing fungemia was: Candida albicans (5), Candida tropicalis (16), Candida parapsilosis (6), Candida guilliermondii (4),
Candida lusitaniae (1) and Candida stellatoidea (1). Antifungal prophylaxis had been administered before the episode of fungemia
in only six patients (18.2%): oral itraconazole in three patients and oral nistatin, low dose intravenous amphotericin B and
oral fluconazole in one patient each. There was no difference in the presence of risk factors, clinical characteristics or
in the outcome between albicans and non-albicans species, nor between Candida tropicalis and other non-albicans species. There
was a clear predominance of non-albicans species, regardless of the underlying disease, antifungal prophylaxis or the presence
of neutropenia.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
69.
70.
Random amplified polymorphic DNA (RAPD) is based on DNA amplification by polymerase chain reaction (PCR) of random DNA segments using single arbitrary nucleotide sequences. We have adapted the assay to soybeans by using Stoffel Fragment DNA polymerase and by optimizing the reaction conditions. To increase the percentage of RAPD polymorphisms, the DNA template was digested with restriction enzymes before amplification. The combination of twenty-four primers and five DNA template treatments (Undigested, DraI, EcoRI, HindIII, and TaqI digested) revealed 94 polymorphic DNA fragments differing between soybean lines PI437654 and BSR101. Many polymorphic DNA bands were found unreliable or non-scoreable after re-screening of primers and verification of marker-allele segregation with 20 recombinant inbred lines (RILs). However, 28 RAPD markers were consistently polymorphic between the parental lines and followed Mendelian expectations. The use of DNA templates digested with DraI, EcoRI, HindIII or TaqI increased three times the number of RAPD markers compared to undigested DNA template alone. The 28 RAPD markers obtained were further screened with 72 RILs and placed on an existing RFLP map. 相似文献