全文获取类型
收费全文 | 9680篇 |
免费 | 792篇 |
国内免费 | 9篇 |
专业分类
10481篇 |
出版年
2023年 | 42篇 |
2022年 | 79篇 |
2021年 | 170篇 |
2020年 | 111篇 |
2019年 | 109篇 |
2018年 | 160篇 |
2017年 | 128篇 |
2016年 | 270篇 |
2015年 | 411篇 |
2014年 | 499篇 |
2013年 | 624篇 |
2012年 | 775篇 |
2011年 | 758篇 |
2010年 | 453篇 |
2009年 | 441篇 |
2008年 | 595篇 |
2007年 | 645篇 |
2006年 | 609篇 |
2005年 | 527篇 |
2004年 | 534篇 |
2003年 | 511篇 |
2002年 | 508篇 |
2001年 | 109篇 |
2000年 | 81篇 |
1999年 | 115篇 |
1998年 | 147篇 |
1997年 | 103篇 |
1996年 | 94篇 |
1995年 | 104篇 |
1994年 | 87篇 |
1993年 | 82篇 |
1992年 | 89篇 |
1991年 | 39篇 |
1990年 | 48篇 |
1989年 | 34篇 |
1988年 | 37篇 |
1987年 | 23篇 |
1986年 | 33篇 |
1985年 | 31篇 |
1984年 | 27篇 |
1983年 | 27篇 |
1982年 | 37篇 |
1981年 | 29篇 |
1980年 | 22篇 |
1979年 | 19篇 |
1978年 | 11篇 |
1977年 | 24篇 |
1976年 | 17篇 |
1974年 | 8篇 |
1973年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
21.
Bilateral electrolytic lesions restricted to the lateral, basolateral and basomedial amygdaloid nuclei in mice produced a lack of avoidance responses towards novel stimuli. While controls showed avoidance and burying reactions to a novel object introduced into their familiar environment, lesioned mice displayed a high number of approach responses and a low level of burying reactions. Furthermore, when given the opportunity to move around freely in simultaneously presented novel and familiar places, control mice at first exhibited avoidance reactions to the novel environment before showing novelty preference. There were no avoidance reactions in lesioned mice. These data are consistent with the hypothesis that amygdala plays a specific role in the regulation of defensive reactions. 相似文献
22.
23.
24.
The G antigen is one of the erythrocyte membrane Rh antigens. The amount of Rh antigen present on the red blood cell is about 10(-15) g and radioactive labeling of membrane proteins is a useful method for its identification and characterization. In this paper, we compare 4 labeling techniques. Using a human monoclonal anti-Rh(G) antibody and an immunofixation technique, we located the G antigen on a polypeptide of an average molecular weight of 28,000 Da. 相似文献
25.
Anne Izard Gérard Goma Philippe Soucaille 《Applied microbiology and biotechnology》1989,31(2):179-183
Summary The inhibitory effect of various alkanols, benzyl alcohol and phenethyl alcohol on the growth rate of Clostridium acetobutylicum ATCC 824 was investigated. Inhibition of cell growth was studied by treating cultures with varied concentrations of alcohols. There was a threshold concentration above which growth inhibition occurred. The degree of inhibition was a linear function of the alcohol concentration used. The natural logarithm of the inhibition constant was shown to be: (1) a linear function of the chain length of the alkanols, (2) a linear function of the natural logarithm of the octanol/water partition coefficient for both aliphatic and cyclic alcohols. 相似文献
26.
Philippe Frachet Georges Uzan Dominique Thevenon Eric Denarier Marie Hélène Prandini Gérard Marguerie 《Molecular biology reports》1990,14(1):27-33
Platelet GPIIbIIIa is only synthesized in megakaryocyte or in cell lines with megakaryocytic features. The sequence for GPIIb and GPIIIa have recently been derived from cDNAs obtained from HEL cells. The sequence of these proteins produced by the megakaryocyte, has however, not been determined yet. This study describes full length cDNAs for GPIIb and GPIIIa isolated from megakaryocyte cDNA libraries. The cDNA sequences indicate the presence of nucleotide differences, between the sequence of the GPIIIa cDNAs from HEL cells, endothelial cells and megakaryocytes. One difference was also observed between HEL and megakaryocyte GPIIb at position 633 where a cystein in the megakaryocyte GPIIb, is replaced by a serine in the HEL sequence. The mRNA species for GPIIb (3.4kb) and GPIIIa (6.1 kb) were of the same size in HEL cells and human megakaryocytes. 相似文献
27.
28.
29.
Tuffery Pierre; Dessen Philippe; Mugnier Claude; Hazout Serge 《Bioinformatics (Oxford, England)》1988,4(1):103-110
We have developed a new algorithm Complete sentencescompatibility (CSC) which uses single and double digestionfragments to rapidly determine restriction maps of circularDNA. From possible combinations of fragments of each simpledigestion, which we call sentences of decomposition,we construct a restriction map which combines the sentenceswhile taking into account compatibility rules. The algorithmcan also deal with experimental errors of fragment weight andcan suggest solutions that account for non-readable bands (fragmentsof zero length or multiple bands) on the gel. Because experimentsusing pairs of restrictive enzymes often result in multiplesolutions, a complementary algorithm tries to reduce the numberof proposed solutions by establishing consensus maps. The restrictionmap construction algorithm was tested on real cases, some containingmore than fifteen fragments. Execution times range from 1 10 s on an IBM PC compatible microcomputer.
Received on July 21, 1987; accepted on December 31, 1987 相似文献
30.
Human cyclin E, a new cyclin that interacts with two members of the CDC2 gene family. 总被引:103,自引:0,他引:103
A new human cyclin, named cyclin E, was isolated by complementation of a triple cln deletion in S. cerevisiae. Cyclin E showed genetic interactions with the CDC28 gene, suggesting that it functioned at START by interacting with the CDC28 protein. Two human genes were identified that could interact with cyclin E to perform START in yeast containing a cdc28 mutation. One was CDC2-HS, and the second was the human homolog of Xenopus CDK2. Cyclin E produced in E. coli bound and activated the CDC2 protein in extracts from human G1 cells, and antibodies against cyclin E immunoprecipitated a histone H1 kinase from HeLa cells. The interactions between cyclin E and CDC2, or CDK2, may be important at the G1 to S transition in human cells. 相似文献