全文获取类型
收费全文 | 665790篇 |
免费 | 75058篇 |
国内免费 | 929篇 |
出版年
2018年 | 5890篇 |
2016年 | 8040篇 |
2015年 | 11632篇 |
2014年 | 13385篇 |
2013年 | 18785篇 |
2012年 | 21443篇 |
2011年 | 22073篇 |
2010年 | 14743篇 |
2009年 | 13426篇 |
2008年 | 19643篇 |
2007年 | 20227篇 |
2006年 | 19082篇 |
2005年 | 18314篇 |
2004年 | 18237篇 |
2003年 | 17325篇 |
2002年 | 16784篇 |
2001年 | 27700篇 |
2000年 | 27697篇 |
1999年 | 22103篇 |
1998年 | 8342篇 |
1997年 | 8514篇 |
1996年 | 8142篇 |
1995年 | 7647篇 |
1994年 | 7331篇 |
1993年 | 7344篇 |
1992年 | 18640篇 |
1991年 | 18543篇 |
1990年 | 18077篇 |
1989年 | 17493篇 |
1988年 | 16237篇 |
1987年 | 15392篇 |
1986年 | 14439篇 |
1985年 | 14497篇 |
1984年 | 12048篇 |
1983年 | 10308篇 |
1982年 | 7958篇 |
1981年 | 7250篇 |
1980年 | 6762篇 |
1979年 | 11469篇 |
1978年 | 9122篇 |
1977年 | 8385篇 |
1976年 | 7836篇 |
1975年 | 8889篇 |
1974年 | 9776篇 |
1973年 | 9541篇 |
1972年 | 8528篇 |
1971年 | 7931篇 |
1970年 | 6853篇 |
1969年 | 6699篇 |
1968年 | 6156篇 |
排序方式: 共有10000条查询结果,搜索用时 296 毫秒
941.
The structure of the tightly bound complex of the globular myosin head with F-actin is the key to understanding important details of the mechanism of how the actin-myosin motor functions. The current notion on this complex is based on the docking of known atomic structures of constituent proteins into low-resolution electron-density maps. The atomic structure of the complex was refined by the molecular mechanics method, which consists in minimizing the energy of molecular interaction and which makes it possible to optimize not only the relative position of protein backbones as rigid bodies, but also the position of side chains on the protein interface. The structure calculated using ICM-Pro software, on the one hand, is close to the model obtained using electron microscopy; on the other hand, it ensures the best calculated interaction energy and accounts for the results of mutagenesis experiments. On the basis of the structure obtained, we can suggest the molecular mechanisms underlying the actin-activated release of ATP hydrolysis products from myosin and the decrease in the affinity of myosin for actin upon binding of nucleotides. 相似文献
942.
943.
The morphology of dissociated single cerebellar Purkinje cells obtained from wild-type P1 CD1 mice was assessed in the absence
and in the presence of glia. A dedicated noninvasive technique based on optical microscopy was developed. Image processing
algorithms were implemented to extract metrical features characterizing cell structure and dendritic arborization. The morphological
features were analyzed in order to identify quantitative differences in Purkinje cell morphology due to interactions with
astrocytes. 相似文献
944.
D. Padilla F. Acosta J. A. García F. Real Jose R. Vivas 《Archives of microbiology》2009,191(3):191-198
Hafnia alvei, a Gram negative bacillus related to the Enterobacteriaceae family, is considered an opportunistic pathogen of several animal species and humans. In this communication, we describe
fimbrial-like structures from different strains of H. alvei that cannot be easily ascribed to any of the previously reported fimbrial types in this species (type I or type III). Polymerase
chain reaction (PCR) and immunofluorescence assays were carried out to study fimbriae and flagella in H. alvei strains isolated from different sources. No correlation between the results obtained by PCR and those obtained by phenotypic
methods were found, and the antibodies used gave cross or different recognition patterns of the surface structures present
in these strains. We report as well that strain and growth temperature influence fimbriation and expression of flagella in
human and animal isolates of H. alvei. This study also indicates that the absence of fimbriae have a significant positive influence on the initial adhesion of
H. alvei to human epithelial cells. 相似文献
945.
Ronald J. Roberts H. J. Ball A. L. S. Munro W. M. Shearer 《Journal of fish biology》1971,3(2):221-224
Fourteen fresh run salmon Satmo salar L. with early extant lesions of ulcerative dermal necrosis (UDN) were kept in separate tanks and treated with zinc free malachite green. Ten of the fish were held at 10° C and 4 at 2° C. The treatment precluded infection with Saprolegnia fungus and allowed natural resolution of the lesions. There was a marked difference in rate of healing between warm and cold water conditions.
Histological examination of healing lesions at different stages showed that there was a primary invasion of cuboidal epithelium over the collagen scar followed by a phase of disorganized proliferation which eventually organized itself into normal epithelium. Melanocytes were very obvious in the dermis of healing lesions. 相似文献
Histological examination of healing lesions at different stages showed that there was a primary invasion of cuboidal epithelium over the collagen scar followed by a phase of disorganized proliferation which eventually organized itself into normal epithelium. Melanocytes were very obvious in the dermis of healing lesions. 相似文献
946.
947.
cDNA sequence and predicted primary structure of the gamma subunit from the ATP synthase from Chlamydomonas reinhardtii 总被引:3,自引:0,他引:3
The 1701-base nucleotide sequence (not including the poly(A) tail) of a cDNA for the gamma subunit of the ATP synthase from Chlamydomonas reinhardtii was determined. A start translation sequence, 23 bases in from the 5' end, initiates an 1074-base-long open reading frame. The sequence of the first 21 amino acids at the amino-terminal end of the mature gamma subunit from C. reinhardtii was determined and compared to the deduced amino acid sequence of the open reading frame. From this it was determined that the mature protein contains 323 amino acids, with the first 35 amino acids probably being part of the transit peptide. The length of the mature protein is the same as that for the mature gamma subunit from spinach, for which only a few of the amino acids of the transit peptide are known. The similarity of the two mature proteins at the nucleotide level is 56% while at the amino acid level it is 77%. In addition, the 3 cysteines, which in spinach are involved in the energy-linked catalytic functions of the ATP synthase, are conserved in the predicted amino acid sequence for the gamma subunit from C. reinhardtii. In contrast, the mature C. reinhardtii gamma subunit contains 3 additional cysteine residues not found in the spinach gamma subunit. 相似文献
948.
Jesse L. Steinfeld 《The Western journal of medicine》1984,141(6):878-883
Although cigarette smoking is the number one public health problem in the United States, physicians have failed to take the lead either in convincing youngsters not to begin smoking or in aiding adults to quit smoking. To be most effective and convincing in combating the smoking epidemic, practicing physicians must have the same basic fund of knowledge about the short- and long-term consequences of smoking as they do about other commonly encountered medical problems. By acting on such knowledge and adopting a definite set of attitudes and activities in their offices and with patients, physicians can make a significant contribution to their patients and to the entire community in which they practice. 相似文献
949.
F. Le Dantec 《Molecular & general genetics : MGG》1910,4(1):144-145
Ohne Zusammenfassung 相似文献
950.