全文获取类型
收费全文 | 1159篇 |
免费 | 112篇 |
出版年
2023年 | 22篇 |
2022年 | 10篇 |
2021年 | 51篇 |
2020年 | 42篇 |
2019年 | 46篇 |
2018年 | 43篇 |
2017年 | 32篇 |
2016年 | 56篇 |
2015年 | 92篇 |
2014年 | 83篇 |
2013年 | 84篇 |
2012年 | 113篇 |
2011年 | 105篇 |
2010年 | 55篇 |
2009年 | 34篇 |
2008年 | 63篇 |
2007年 | 47篇 |
2006年 | 46篇 |
2005年 | 23篇 |
2004年 | 29篇 |
2003年 | 35篇 |
2002年 | 21篇 |
2001年 | 6篇 |
2000年 | 4篇 |
1999年 | 9篇 |
1998年 | 7篇 |
1997年 | 6篇 |
1996年 | 6篇 |
1994年 | 5篇 |
1993年 | 6篇 |
1992年 | 8篇 |
1991年 | 12篇 |
1990年 | 7篇 |
1989年 | 10篇 |
1988年 | 5篇 |
1987年 | 4篇 |
1986年 | 7篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1980年 | 5篇 |
1979年 | 3篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1974年 | 4篇 |
1973年 | 4篇 |
1970年 | 1篇 |
1967年 | 1篇 |
1962年 | 1篇 |
1938年 | 1篇 |
1928年 | 1篇 |
排序方式: 共有1271条查询结果,搜索用时 236 毫秒
1.
Nathalie Jeanray Rapha?l Marée Benoist Pruvot Olivier Stern Pierre Geurts Louis Wehenkel Marc Muller 《PloS one》2015,10(1)
Zebrafish is increasingly used to assess biological properties of chemical substances and thus is becoming a specific tool for toxicological and pharmacological studies. The effects of chemical substances on embryo survival and development are generally evaluated manually through microscopic observation by an expert and documented by several typical photographs. Here, we present a methodology to automatically classify brightfield images of wildtype zebrafish embryos according to their defects by using an image analysis approach based on supervised machine learning. We show that, compared to manual classification, automatic classification results in 90 to 100% agreement with consensus voting of biological experts in nine out of eleven considered defects in 3 days old zebrafish larvae. Automation of the analysis and classification of zebrafish embryo pictures reduces the workload and time required for the biological expert and increases the reproducibility and objectivity of this classification. 相似文献
2.
B?rbel Maus Camille Jung Jestinah M. Mahachie John Jean-Pierre Hugot Emmanuelle Génin Kristel Van Steen 《PloS one》2013,8(10)
Complex human diseases commonly differ in their phenotypic characteristics, e.g., Crohn’s disease (CD) patients are heterogeneous with regard to disease location and disease extent. The genetic susceptibility to Crohn’s disease is widely acknowledged and has been demonstrated by identification of over 100 CD associated genetic loci. However, relating CD subphenotypes to disease susceptible loci has proven to be a difficult task. In this paper we discuss the use of cluster analysis on genetic markers to identify genetic-based subgroups while taking into account possible confounding by population stratification. We show that it is highly relevant to consider the confounding nature of population stratification in order to avoid that detected clusters are strongly related to population groups instead of disease-specific groups. Therefore, we explain the use of principal components to correct for population stratification while clustering affected individuals into genetic-based subgroups. The principal components are obtained using 30 ancestry informative markers (AIM), and the first two PCs are determined to discriminate between continental origins of the affected individuals. Genotypes on 51 CD associated single nucleotide polymorphisms (SNPs) are used to perform latent class analysis, hierarchical and Partitioning Around Medoids (PAM) cluster analysis within a sample of affected individuals with and without the use of principal components to adjust for population stratification. It is seen that without correction for population stratification clusters seem to be influenced by population stratification while with correction clusters are unrelated to continental origin of individuals. 相似文献
3.
4.
Cytoplasmic Poly(ADP-Ribose) Polymerase Associated with Free Messenger Ribonucleoprotein Particles in Rat Brain 总被引:1,自引:0,他引:1
Poly(ADP-ribose) polymerase associated with free cytoplasmic messenger ribonucleoprotein particles (free mRNP particles) carrying messenger RNA has been characterized in rat brain. There were first-order kinetics for NAD with an apparent Km for NAD of 90.5 +/- 0.70 microM and Vmax of 19.7 +/- 2.8 pmol ADP-ribose incorporated min-1 mg protein-1. Five poly(ADP-ribose) protein acceptors were identified in the Mr 37,000-120,000 range. It is hypothesized that ADP-ribosylation of specific free mRNP proteins might play a role in the derepression and translation of the silent mRNAs of free mRNP particles. 相似文献
5.
M Ayane L Mengle-Gaw H O McDevitt C Benoist D Mathis 《Journal of immunology (Baltimore, Md. : 1950)》1986,137(3):948-951
H-2u haplotype mice are unique among all E alpha+ strains because they do not provide in heterozygotes an E alpha chain that interacts with E betak,s,etc. sufficiently well to allow certain E-restricted immune responses. As a first step in understanding this peculiarity, we have sequenced E alpha u and E beta u cDNA and compared the derived amino acid sequences with those of previously analyzed alleles. Although no glaring structural abnormalities were found, we have identified some u-specific residues and suggest which are the most likely to provoke a pairing anomaly. 相似文献
6.
The murine E alpha immune response gene 总被引:26,自引:0,他引:26
7.
1. The separation of the alpha-components of codfish-skin and calf-skin collagen from the higher-molecular-weight components was accomplished by gel filtration with Bio-Gel P-300 resin in 5m-lithium chloride and at pH7.4. 2. From this fraction three distinct alpha-components, corresponding to the alpha1-, alpha2- and alpha3- chains of collagen, were isolated by free-flow electrophoresis in 6m-urea at 4 degrees . At the temperatures and pH values used there was no detectable degradation of the alpha-chains. 相似文献
8.
Superantigens, including the staphylococcal enterotoxins and the minor lymphocyte stimulatory antigens, are highly potent immunostimulatory molecules, capable of activating virtually all T cells that express particular T cell receptor (TCR) variable regions. Superantigen stimulation of T lymphocytes depends on major histocompatibility complex (MHC) class II molecules, so there has been some debate as to whether superantigens interact with the antigen binding "groove" on class II complexes, just like conventional peptide antigens, or whether they bind elsewhere and serve as TCR coligands. We compared the presentation of peptide antigens and superantigens by a panel of mutant-presenting cell lines, each displaying an A kappa alpha chain with a single alanine replacement along the alpha helix proposed to form one face of the groove. The negligible effect of these 30 mutations on superantigen presentation, versus their drastic consequences for peptide presentation, prompts us to conclude that superantigens interact with MHC class II molecules outside the groove. 相似文献
9.
Jan Klein Christophe Benoist Chella S. David Peter Demant Kirsten Fischer Lindahl Lorraine Flaherty Richard A. Flavell Ulrich Hämmerling Leroy E. Hood Stephen W. Hunt III Patricia P. Jones Philippe Kourilsky Hugh O. McDevitt Daniel Meruelo Donal B. Murphy Stanley G. Nathenson David H. Sachs Michael Steinmetz Susumu Tonegawa Edward K. Wakeland Elizabeth H. Weiss 《Immunogenetics》1990,32(3):147-149
10.
Martina Ferraguti Sergio Magallanes Jéssica Jiménez-Peñuela Josué Martínez-de la Puente Luz Garcia-Longoria Jordi Figuerola Jaime Muriel Tamer Albayrak Staffan Bensch Camille Bonneaud Rohan H. Clarke Gábor Á. Czirják Dimitar Dimitrov Kathya Espinoza John G. Ewen Farah Ishtiaq Wendy Flores-Saavedra László Zsolt Garamszegi Olof Hellgren Dita Horakova Kathryn P. Huyvaert Henrik Jensen Asta Križanauskienė Marcos R. Lima Charlene Lujan-Vega Eyðfinn Magnussen Lynn B. Martin Kevin D. Matson Anders Pape Møller Pavel Munclinger Vaidas Palinauskas Péter L. Pap Javier Pérez-Tris Swen C. Renner Robert Ricklefs Sergio Scebba Ravinder N. M. Sehgal Manuel Soler Eszter Szöllősi Gediminas Valkiūnas Helena Westerdahl Pavel Zehtindjiev Alfonso Marzal 《Global Ecology and Biogeography》2023,32(5):809-823