首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   10137篇
  免费   668篇
  国内免费   2篇
  2023年   57篇
  2022年   131篇
  2021年   268篇
  2020年   141篇
  2019年   201篇
  2018年   232篇
  2017年   223篇
  2016年   355篇
  2015年   522篇
  2014年   585篇
  2013年   732篇
  2012年   790篇
  2011年   767篇
  2010年   544篇
  2009年   413篇
  2008年   572篇
  2007年   534篇
  2006年   558篇
  2005年   475篇
  2004年   489篇
  2003年   421篇
  2002年   402篇
  2001年   135篇
  2000年   86篇
  1999年   107篇
  1998年   93篇
  1997年   94篇
  1996年   67篇
  1995年   41篇
  1994年   52篇
  1993年   46篇
  1992年   49篇
  1991年   44篇
  1990年   38篇
  1989年   38篇
  1988年   34篇
  1987年   31篇
  1986年   29篇
  1985年   35篇
  1984年   35篇
  1983年   32篇
  1982年   38篇
  1981年   32篇
  1980年   31篇
  1979年   21篇
  1977年   16篇
  1976年   15篇
  1975年   15篇
  1974年   13篇
  1973年   20篇
排序方式: 共有10000条查询结果,搜索用时 125 毫秒
951.

Background

IgE recognition of panallergens having highly conserved sequence regions, structure, and function and shared by inhalant and food allergen sources is often observed.

Methods

We evaluated the IgE recognition profile of profilins (Bet v 2, Cyn d 12, Hel a 2, Hev b 8, Mer a 1, Ole e 2, Par j 3, Phl p 12, Pho d 2), PR-10 proteins (Aln g 1, Api g 1, Bet v 1.0101, Bet v 1.0401, Cor a 1, Dau c 1 and Mal d 1.0108) and tropomyosins (Ani s 3, Der p 10, Hel as 1, Pen i 1, Pen m 1, Per a 7) using the Immuno-Solid phase Allergen Chip (ISAC) microarray system. The three panallergen groups were well represented among the allergenic molecules immobilized on the ISAC. Moreover, they are distributed in several taxonomical allergenic sources, either close or distant, and have a route of exposure being either inhalation or ingestion.

Results

3,113 individuals (49.9% female) were selected on the basis of their reactivity to profilins, PR-10 or tropomyosins. 1,521 (48.8%) patients were reactive to profilins (77.6% Mer a 1 IgE+), 1,420 (45.6%) to PR-10 (92.5% Bet v 1 IgE+) and 632 (20.3%) to tropomyosins (68% Der p 10 IgE+). A significant direct relationship between different representative molecules within each group of panallergens was found. 2,688 patients (86.4%) recognized only one out of the three distinct groups of molecules as confirmed also by hierarchical clustering analysis.

Conclusions

Unless exposed to most of the allergens in the same or related allergenic sources, a preferential IgE response to distinct panallergens has been recorded. Allergen microarray IgE testing increases our knowledge of the IgE immune response and related epidemiological features within and between homologous molecules better describing the patients'' immunological phenotypes.  相似文献   
952.
953.
Mathematical models in biology are powerful tools for the study and exploration of complex dynamics. Nevertheless, bringing theoretical results to an agreement with experimental observations involves acknowledging a great deal of uncertainty intrinsic to our theoretical representation of a real system. Proper handling of such uncertainties is key to the successful usage of models to predict experimental or field observations. This problem has been addressed over the years by many tools for model calibration and parameter estimation. In this article we present a general framework for uncertainty analysis and parameter estimation that is designed to handle uncertainties associated with the modeling of dynamic biological systems while remaining agnostic as to the type of model used. We apply the framework to fit an SIR-like influenza transmission model to 7 years of incidence data in three European countries: Belgium, the Netherlands and Portugal.  相似文献   
954.
955.
956.
The electronic structure of H2M3(CO)9S clusters (M = Ru, Os) is discussed on the basis of their He I and He II excited gas-phase photoelectron spectra and on the basis of CNDO quantum mechanical calculations. The PE data clearly demonstrate the cleavage of two direct MM interactions by operation of the bridging hydrides, giving rise to three-center two-electron MHM levels. The μ3-S bonding mode has been described in detail and compared with previous results on related μ3-CY cluster derivatives. The CNDO results on Ru3(CO)9S=, HRu3(CO)9S? and H2Ru3(CO)9S indicate that the μ3-S—cluster interaction is mostly independent of the presence of the bridging hydrides.  相似文献   
957.
By means of immunocytochemical methods, a secretin-like immunoreactivity is demonstrated in the neural complex of the ascidian Styela plicata. Secretinergic neurons are localized in the cortex of the cerebral ganglion and numerous secretin-like immunoreactive cells are detected in some lobules of the neural gland. The possible functions of secretin-like substances in the ascidian neural complex are discussed.  相似文献   
958.
The known 10-acetoxy-8,9-epoxythymolisobutyrate and the new 8,9-dihydroxy-10-acetoxythymolisobutyrate and 8,9,10-trihydroxythymol have been isolated from the thallus of Eupatorium glechonophyllum. The acetonide of the last compound was also obtained. The possibility that the new compounds are artefacts is discussed.  相似文献   
959.
The mechanism of sexualization of the tubular gonad in seawater bivalves is unknown, and no information regarding the genes involved in this process is yet available, except for the identification of esterase (Est)-like "male-associated polypeptide" in the male gonad of Mytilus galloprovincialis. Our present work reveals distinct protein profiles specific for the testicular or ovarian portion of the ovotestis of Pecten maximus. Two proteins exhibiting testis- or ovary-dependent enrichment in the ovotestis have been identified and partially characterized as Est-like and fibronectin (Fn)-like polypeptides, respectively. Immunofluorescence has demonstrated a close association between the localization of these polypeptides and the gonad tubule network and interstitial stroma of the ovotestis of P. maximus. We also present evidence of Est-like and Fn-like protein enrichment, respectively, in testicular and ovarian tissue in hermaphroditic, sex-reversal, and gonochoric species of seawater bivalves. Together, the results (1) strongly suggest that sex-cell-biased expression of Est-like and Fn-like polypeptides in gonad tissue is a widespread phenomenon among bivalve mollusks, despite the high diversification of their sexual patterns, (2) confirm and expand our previous demonstration of sex-biased protein expression in M. galloprovincialis, and (3) indicate a direct link between germ cell differentiation and sexual specialization of the bivalve somatic gonad.  相似文献   
960.
Confocal laser-scanning microscopy was used to carry out a comparative study of the immunostaining for three families of neuropeptides, viz., allatostatin-A (AS-A), allatostatin-C (AS-C) and allatotropin (AT), in adult female mosquitoes of Aedes aegypti and Anopheles albimanus. The specific patterns of immunostaining for each of the three peptides were similar in both species. The antisera raised against AT, AS-A, and AS-C revealed intense immunoreactivity in the cells of each protocerebral lobe of the brain and stained cells in each of the ventral ganglia and neuronal projections innervating various thoracic and abdominal tissues. Only the AS-A antiserum labeled immunoreactive endocrine cells in the midgut. The distribution of the peptides supports the concept that they play multiple regulatory roles in both species.This work was supported by NIH grant AI 45545 to F.G.N. and CONACyT G-37186-M to M.H.R.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号