全文获取类型
收费全文 | 2002篇 |
免费 | 169篇 |
国内免费 | 2篇 |
专业分类
2173篇 |
出版年
2022年 | 18篇 |
2021年 | 27篇 |
2020年 | 18篇 |
2019年 | 21篇 |
2018年 | 21篇 |
2017年 | 28篇 |
2016年 | 57篇 |
2015年 | 98篇 |
2014年 | 102篇 |
2013年 | 146篇 |
2012年 | 164篇 |
2011年 | 145篇 |
2010年 | 100篇 |
2009年 | 80篇 |
2008年 | 112篇 |
2007年 | 88篇 |
2006年 | 82篇 |
2005年 | 76篇 |
2004年 | 78篇 |
2003年 | 66篇 |
2002年 | 56篇 |
2001年 | 55篇 |
2000年 | 49篇 |
1999年 | 37篇 |
1998年 | 21篇 |
1997年 | 21篇 |
1996年 | 26篇 |
1995年 | 11篇 |
1994年 | 24篇 |
1993年 | 12篇 |
1992年 | 24篇 |
1991年 | 28篇 |
1990年 | 19篇 |
1989年 | 12篇 |
1988年 | 18篇 |
1987年 | 17篇 |
1986年 | 17篇 |
1985年 | 15篇 |
1984年 | 9篇 |
1983年 | 16篇 |
1982年 | 13篇 |
1981年 | 11篇 |
1980年 | 11篇 |
1979年 | 20篇 |
1978年 | 10篇 |
1976年 | 19篇 |
1975年 | 12篇 |
1974年 | 6篇 |
1973年 | 8篇 |
1970年 | 8篇 |
排序方式: 共有2173条查询结果,搜索用时 0 毫秒
1.
Summary The sensory receptor responsive to pressure applied internally to the ventral abdominal body wall of the blood-feeding insects, Rhodnius prolixus, is a single sense cell containing, at its distal end, a cilium enclosed within a scolopale, a densely staining structure characteristic of insect scolopidial sensilla. A small spherical structure lies within a dilation near the midregion of the cilium, and contains nine heavily staining bodies, the position of each corresponding to a pair of microtubules in the cilium. Proximal to the dilation, the microtubules are organized in a ring of nine pairs with one microtubule of each pair associated with dyneinlike arms. Dastal to the dilation a central pair of microtubules is present, but dyneinlike arms are absent. The scolopale cell, which gives risc to the scolopale, has cytoplasmic invaginations that form an elaborate array of extracellular compartments surrounding the body wall of the sense cell. These compartments may serve to dampen high frequency vibrations permitting the receptor to respond to pressure exerted by touch, an attribute in keeping with the receptor's proposed function of detecting abdominal distension related to the size and movement of the stomach. 相似文献
2.
3.
The two-state recurrent stochastic model with time-independent transition rates is generalized to a model with time-dependent transition rates. The rates can be any general function of external time, that is, any general function of the calendar time in which the process unfolds. Formulas for the state transition probabilities, the proportion of individuals in a particular state at time t, the distribution function, and the expectation of the number of individuals in a particular state at time t are derived. 相似文献
4.
5.
A tryptic resistant heme peptide has been prepared and purified from cardiac cytochrome c1. This purified peptide is not further hydrolyzed by reactions of other proteolytic enzymes, such as pronase. The peptide contains 2 residues each of serine, cysteine and valine, and 1 residue each of alanine, methionine, tyrosine, histidine, arginine, proline, glutamic acid (glutamine) and aspartic acid. The intensity of the absorption spectrum of the peptide has been found to be dependent upon, but the positions of the absorption maxima do not vary with, concentration. The heme peptide does not show multiple splitting of absorption peaks at liquid N2 temperatures as does the intact cytochrome C1. However, cyanide rapidly reacts with the peptide and causes significant spectral changes. CD spectra of the peptide exhibit a typical profile of a non-structured heme peptide with positive CD bands in the Soret region and around 250 nm, and a broad negative extreme of 320-360 nm. The similarities and differences between the tryptic resistant heme peptides from cytochromes c1 and c have been compared. 相似文献
6.
7.
Dar-Shong Lin Tzu-Po Chuang Ming-Fu Chiang Che-Sheng Ho Chung-Der Hsiao Yu-Wen Huang Tsu-Yen Wu Jer-Yuarn Wu Yuan-Tsong Chen Tsai-Chuan Chen Ling-Hui Li 《Gene》2014
Xq28 duplications encompassing the methyl CpG binding protein 2 (MECP2) in males exhibit a distinct phenotype, including developmental delay, facial dysmorphism, muscular hypotonia, intellectual disability, poor or absent speech, recurrent infections and early death. The vast majority of affected males inherit the MECP2 duplication from their usually asymptomatic carrier mothers. Only a few cases with Xq28 duplication originating from de novo unbalanced X/Y translocation have been reported and the paternal origin of the aberration has only been validated in three males in the related literature. Here we present a karyotypically normal male with features characteristic of the MECP2 duplication syndrome. The genome-wide SNP genotyping shows a de novo 2.26-Mb duplication from Xq28 to the terminus. The genotypes of the SNPs within the duplicated region indicated a paternal origin. Furthermore, the results of fluorescence in situ hybridization (FISH) indicated a novel Xq:Yp translocation, characterized as der(Y)t(Y;X)(p11.32;q28), which suggests an aberrant that occurred during spermatogenesis. The phenotype is compared to the previously reported cases with Xq28 duplication originated from an unbalanced X/Y translocation, and there was no specific part of the phenotype that could be contributed to the origin of parental imbalances. This report further highlights the capacity of high-molecular cytogenetic methods, such as SNP array and FISH, in the identification of submicroscopic rearrangement, structural configuration and parental origin of aberrant while in the evaluation of children with idiopathic developmental delay and intellectual disability. 相似文献
8.
Hsin-Hou Chang Ya-Wen Chiang Ting-Kai Lin Guan-Ling Lin You-Yen Lin Jyh-Hwa Kau Hsin-Hsien Huang Hui-Ling Hsu Jen-Hung Wang Der-Shan Sun 《PloS one》2014,9(11)
Anthrax lethal toxin (LT), one of the primary virulence factors of Bacillus anthracis, causes anthrax-like symptoms and death in animals. Experiments have indicated that levels of erythrocytopenia and hypoxic stress are associated with disease severity after administering LT. In this study, the granulocyte colony-stimulating factor (G-CSF) was used as a therapeutic agent to ameliorate anthrax-LT- and spore-induced mortality in C57BL/6J mice. We demonstrated that G-CSF promoted the mobilization of mature erythrocytes to peripheral blood, resulting in a significantly faster recovery from erythrocytopenia. In addition, combined treatment using G-CSF and erythropoietin tended to ameliorate B. anthracis-spore-elicited mortality in mice. Although specific treatments against LT-mediated pathogenesis remain elusive, these results may be useful in developing feasible strategies to treat anthrax. 相似文献
9.
10.