全文获取类型
收费全文 | 4186篇 |
免费 | 444篇 |
国内免费 | 269篇 |
出版年
2024年 | 13篇 |
2023年 | 123篇 |
2022年 | 169篇 |
2021年 | 207篇 |
2020年 | 195篇 |
2019年 | 266篇 |
2018年 | 180篇 |
2017年 | 165篇 |
2016年 | 172篇 |
2015年 | 192篇 |
2014年 | 225篇 |
2013年 | 378篇 |
2012年 | 203篇 |
2011年 | 201篇 |
2010年 | 162篇 |
2009年 | 221篇 |
2008年 | 211篇 |
2007年 | 254篇 |
2006年 | 183篇 |
2005年 | 143篇 |
2004年 | 142篇 |
2003年 | 95篇 |
2002年 | 85篇 |
2001年 | 78篇 |
2000年 | 75篇 |
1999年 | 57篇 |
1998年 | 54篇 |
1997年 | 34篇 |
1996年 | 31篇 |
1995年 | 34篇 |
1994年 | 30篇 |
1993年 | 28篇 |
1992年 | 24篇 |
1991年 | 31篇 |
1990年 | 17篇 |
1989年 | 23篇 |
1988年 | 16篇 |
1987年 | 21篇 |
1986年 | 13篇 |
1985年 | 16篇 |
1984年 | 17篇 |
1983年 | 15篇 |
1982年 | 17篇 |
1981年 | 15篇 |
1980年 | 14篇 |
1979年 | 16篇 |
1978年 | 11篇 |
1976年 | 6篇 |
1975年 | 5篇 |
1973年 | 6篇 |
排序方式: 共有4899条查询结果,搜索用时 140 毫秒
1.
Xiao‐Juan Yu Xiao‐Ren Peng Tong‐Huan Li 《Journal of cellular and molecular medicine》2014,18(12):2530-2535
Many studies have examined the association between the FABP2 (rs1799883) Ala54Thr gene polymorphism and type 2 diabetes mellitus risk (T2DM) in various populations, but their results have been inconsistent. To assess this relationship more precisely, A HuGE review and meta‐analysis were performed. The PubMed and CNKI database was searched for case‐control studies published up to April 2014. Data were extracted and pooled odds ratios (OR) with 95% confidence intervals (CI) were calculated. Ultimately, 13 studies, comprising 2020 T2DM cases and 2910 controls were included. Overall, for the Thr carriers (Ala/Thr and Thr/Thr) versus the wild‐type homozygotes (Ala/Ala), the pooled OR was 1.18 (95% CI = 1.04–1.34, P = 0.062 for heterogeneity), for Thr/Thr versus Ala/Ala the pooled OR was 1.17 (95% CI = 1.05–1.41 P = 0.087 for heterogeneity). In the stratified analysis by ethnicity, the significantly risks were found among Asians but not Caucasians. This meta‐analysis suggests that the FABP2 (rs1799883) Ala54Thr polymorphisms are associated with increased susceptibility to T2DM risk among Asians but not Caucasians. 相似文献
2.
《Cell reports》2020,30(1):61-68.e4
- Download : Download high-res image (250KB)
- Download : Download full-size image
3.
4.
Pascal Griesmar Clément Sanchez Germain Puccetti Isabelle Ledoux Joseph Zyss 《Molecular Engineering》1991,1(3):205-220
Orientation of optically nonlinear organic molecules inside sol-gel matrices upon application of an external D.C. electrical field is demonstrated for the first time. The quadratic nonlinear response of silicon oxide or transition metal oxide based gels containing organic molecules has been determined from Electric Field Induced Second Harmonic (EFISH) measurements. Large concentrations of Optically Nonlinear Organic Molecules (ONOM) have been either incorporated inside the macromolecular network or chemically bonded to the oxide backbone of the gels. These results demonstrate the feasibility of permanently poled doped sol-gel matrices. Moreover, EFISH measurements performed on organic molecules appear to be a useful tool for monitoring the changes occurring during sol-gel transformations. 相似文献
5.
6.
A robust method for selection of variables with the greatest discriminatory power is presented in the paper. The method deals with the two groups of data problem. An application of the method to some respiratory disease data and comparisons with classical procedures are given, also. 相似文献
7.
8.
9.
The advantage of using terrestrial isopods in toxicity studies is that a battery of parameters can be tested at different levels of biological complexity. Feeding parameters for example link organism level response to potential ecological consequences but a problem with using feeding parameters in toxicity tests with terrestrial isopods is their high variability. The aim of our study was to set benchmark values for feeding parameters for isopod Porcellio
scaber (Isopoda, Crustacea) in laboratory-controlled experiments. In the work presented here, the daily feeding rate of the central 50% of the control population of Porcellio
scaber and a correlation between feeding rate and isopod weight were set. Values outside these ranges need additional evaluation to increase the relevance of test outcomes. We suggest using benchmark values for feeding parameters as well as the coefficient of variation (a) to identify animals with altered feeding parameters with respect to controls, and (b) to assess the data quality in each experiment. 相似文献
10.
Post-mortem human subjects (PMHS) are frequently used to characterize biomechanical response and injury tolerance of humans to various types of loading by means of instrumentation installed directly on the skeleton. Data extracted from such tests are often used to develop and validate anthropomorphic test devices (ATDs), which function as human surrogates in tests for injury assessment. Given that the location and orientation of installed instrumentation differs between subjects, nominally similar measurements made on different PMHS must be transformed to standardized, skeletal-based local coordinate systems (LCS) before appropriate data comparisons can be made. Standardized PMHS LCS that correspond to ATD instrumentation locations and orientations have not previously been published. This paper introduces anatomically-defined PMHS LCS for body regions in which kinematic measurements are made using ATDs. These LCS include the head, sternum, single vertebrae, pelvis, femurs (distal and proximal), and tibiae (distal and proximal) based upon skeletal landmarks extracted from whole body CT scans. The proposed LCS provide a means to standardize the reporting of PMHS data, and facilitate both the comparison of PMHS impact data across institutions and the application of PMHS data to the development and validation of ATDs. 相似文献