全文获取类型
收费全文 | 7847篇 |
免费 | 852篇 |
国内免费 | 2篇 |
出版年
2023年 | 46篇 |
2022年 | 75篇 |
2021年 | 187篇 |
2020年 | 110篇 |
2019年 | 132篇 |
2018年 | 162篇 |
2017年 | 156篇 |
2016年 | 230篇 |
2015年 | 362篇 |
2014年 | 406篇 |
2013年 | 454篇 |
2012年 | 617篇 |
2011年 | 615篇 |
2010年 | 383篇 |
2009年 | 314篇 |
2008年 | 462篇 |
2007年 | 452篇 |
2006年 | 385篇 |
2005年 | 371篇 |
2004年 | 397篇 |
2003年 | 338篇 |
2002年 | 312篇 |
2001年 | 119篇 |
2000年 | 84篇 |
1999年 | 108篇 |
1998年 | 79篇 |
1997年 | 66篇 |
1996年 | 49篇 |
1995年 | 49篇 |
1994年 | 40篇 |
1993年 | 31篇 |
1992年 | 70篇 |
1991年 | 70篇 |
1990年 | 47篇 |
1989年 | 55篇 |
1988年 | 37篇 |
1987年 | 40篇 |
1986年 | 43篇 |
1985年 | 51篇 |
1984年 | 55篇 |
1983年 | 41篇 |
1982年 | 27篇 |
1981年 | 28篇 |
1980年 | 30篇 |
1979年 | 32篇 |
1978年 | 32篇 |
1977年 | 35篇 |
1976年 | 28篇 |
1974年 | 29篇 |
1972年 | 29篇 |
排序方式: 共有8701条查询结果,搜索用时 15 毫秒
121.
Sebastian Voigt Reinhart Gossrau Oliver Baum Klemens L?ster Werner Hofmann Werner Reutter 《The Histochemical journal》1995,27(2):123-132
Summary The 11-integrin is known to be a receptor for collagen and laminin mediating cell-matrix interactions. A monoclonal antibody, 33.4, which specifically inhibits the 1-integrin-mediated in vitro cell-collagen binding of rat hepatocytes and hepatoma-derived A-cells (Löster et al., 1994), was used to purify by immunoaffinity chromatography the 1-integrin subunit from rat liver in large quantities for inducing a polyclonal antiserum. In immunoblot analysis on membrane extracts of several rat organs this polyclonal antiserum recognized only a 190 kDa-band, suggesting that it is highly specific for the 1-integrin subunit. A sandwich-ELISA with monoclonal antibody 33.4 and the polyclonal antiserum against the 1-integrin subunit, respectively, enabled the quantitative expression pattern of the 1-integrin subunit to be studied in different rat organs. With the exceptions of brain (not detectable) and muscle (low concentration), the 1-integrin subunit was detectable in almost all organs of the digestive, respiratory and urogenital system as well as in lymphatic organs. The highest relative concentrations of 1-integrin subunit were found in uterus, lung and spleen, whereas in seminal vesicle, stomach, parotid gland, epididymis, kidney and liver only modest concentrations were evident. The organ distribution and localization of 1-integrin subunit were studied by immunohistochemistry with monoclonal and polyclonal antibodies. Immunoreactivity was present in the plasma membranes of all smooth muscle cells, vascular endothelial cells of many organs and fibrocyte-fibroblast sheaths in the heart and kidney. Since these cells are in close contact with collagen-containing basal membranes as well as reticular fibrils, strong evidence exists that in rat tissues the 1-integrin subunit is expressed at sites where collagen is present and might be involved in vivo in cell—ollagen binding.Dedicated to Professor Peter Sitte on the occasion of his 65th birthday 相似文献
122.
Dianne C. Glayzer Ian N. Roberts David B. Archer Richard P. Oliver 《Molecular & general genetics : MGG》1995,249(4):432-438
A transposable element has been isolated from the industrially important fungus Aspergillus niger (strain N402). The element was identified as an insertion sequence within the coding region of the nitrate reductase gene. It had inserted at a TA site and appeared to have duplicated the target site upon insertion. The isolated element was found to be 4798 by in length and contained 37-bp inverted, imperfect, terminal repeats (ITRs). The sequence of the central region of the element revealed an open reading frame (designated ORF1) which showed similarity, at the amino acid level, to the transposase of the Tc1/mariner class of DNA transposons. Another sequence within the central region of the element showed similarity to the 3 coding and downstream untranslated region of the amyA gene of A. niger. Sequence homology and structural features indicate that this element, which has been named Ant1 (A. niger transposon 1), is related to the Tc1/mariner group of DNA transposons. Ant1 is apparently present as a single copy in strain N402 of A. niger. 相似文献
123.
Bernadette Coddeville Antonin Stratil Jean-Michel Wieruszeski Ronald W. A. Oliver Brian N. Green Genevieve Spik 《Glycoconjugate journal》1995,12(5):645-650
The hemopexin phenotype HpxB1 isolated from sheep serum, yields three major bands when subjected to starch gel and/or polyacrylamide gel electrophoresis which are here designated as subcomponents HpxB1-I, HpxB1-II and HpxB1-III. Electrospray mass spectrometric analysis of samples of the isolated subcomponents prepared by ion exchange chromatography showed that each was composed of three glycoproteins and that the major difference between the subcomponents was due to their constituent glycoproteins possessing different numbers of sialic acid residues. Combined analysis of the ESI-MS data and of the overall carbohydrate compositional data obtained by colorimetric procedures, leads to the composition of the glycan of each glycoprotein, and a combined methylation and 400 MHz H-NMR analysis of the alkaline cleaved glycans identified them as being of only the biantennaryN-acetyllactosamine type. Taking into account the molecular mass, the carbohydrate content and structure it may be concluded that each of the constituent glycoproteins contain fiveN-glycosidically linked glycans.Abbreviations HpxB1
hemopexin phenotype B1
- Man
mannose
- Gal
galactose
- GlcNAc
N-acetylglucosamine
- NeuAc
N-acetylneuraminic acid
- GlcNAc-ol
N-acetylglucosaminitol 相似文献
124.
Curtis W. Adams Oliver Nanassy Reid C. Johnson & Kelly T. Hughes 《Molecular microbiology》1997,24(6):1235-1247
The Hin recombinase mediates the site-specific inversion of a segment of the Salmonella chromosome between two flanking 26 bp hix DNA recombination sites. Mutations in two amino acid residues, R43 and R69 of the catalytic domain of the Hin recombinase, were identified that can compensate for loss of binding resulting from elimination of certain major and minor groove contacts within the hix recombination sites. With one exception, the R43 and R69 mutants were also able to bind a hix sequence with an additional 4 bp added to the centre of the site, unlike wild-type Hin. Purified Hin mutants R43H and R69C had both partial cleavage and inversion activities in vitro while mutants R43L, R43C, R69S, and R69P had no detectable cleavage and inversion activities. These data support a model in which the catalytic domain plays a role in DNA-binding specificity, and suggest that the arginine residues at positions 43 and 69 function to position the Hin recombinase on the DNA for a step in the recombination reaction which occurs either at and/or prior to DNA cleavage. 相似文献
125.
126.
Clinical and Molecular Characterization of Patients with Distal 11q Deletions 总被引:10,自引:0,他引:10
下载免费PDF全文
![点击此处可从《American journal of human genetics》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Laura A. Penny Marie Dell'Aquila Marilyn C. Jones JoAnn Bergoffen Christopher Cunniff Jean-Pierre Fryns Elizabeth Grace John M. Graham Boris Kousseff Teresa Mattina James Syme Lucille Voullaire Leopoldo Zelante Julie Zenger-Hain Oliver W. Jones Glen A. Evans 《American journal of human genetics》1995,56(3):676-683
Jacobsen syndrome is caused by segmental aneusomy for the distal end of the long arm of chromosome 11. Typical features include mild to moderate psychomotor retardation, trigonocephaly, facial dysmorphism, cardiac defects, and thrombocytopenia, though none of these features are invariably present. To define the critical regions responsible for these abnormalities, we studied 17 individuals with de novo terminal deletions of 11q. The patients were characterized in a loss-of-heterozygosity analysis using polymorphic dinucleotide repeats. The breakpoints in the complete two-generation families were localized with an average resolution of 3.9 cM. Eight patients with the largest deletions extending from 11q23.3 to 11qter have breakpoints, between D11S924 and D11S1341. This cytogenetic region accounts for the majority of 11q− patients and may be related to the FRA11B fragile site in 11q23.3. One patient with a small terminal deletion distal to D11S1351 had facial dysmorphism, cardiac defects, and thrombocytopenia, suggesting that the genes responsible for these features may lie distal to D11S1351. Twelve of 15 patients with deletion breakpoints as far distal as D11S1345 had trigonocephaly, while patients with deletions distal to D11S912 did not, suggesting that, if hemizygosity for a single gene is responsible for this dysmorphic feature, the gene may lie distal to D11S1345 and proximal to D11S912. 相似文献
127.
Changes in DNA supertwist as a response of Bacillus subtilis towards different kinds of stress 总被引:1,自引:0,他引:1
Abstract The silent parD ( kis/kid ) stability operon of plasmid R1 is normally repressed by the co-ordinated action of the Kis and Kid proteins. In this report it is shown that a mutation in repA , the gene of the plasmid replication protein, that reduces two-fold the copy number of the plasmid, leads to the derepression of the parD system. This derepression can be prevented by a suppressor mutation in copB, a copy number control gene of plasmid R1, that increases the efficiency of replication of the repA mutant. Derepression of the wild-type parD system leads to high plasmid stability. These data show the activation of a plasmid stability operon by a mutation that reduces the efficiency of wild-type plasmid replication. 相似文献
128.
A newZornia species from Cuba, the endemicZornia arenicola sp. nova, is described. It was found on moving sand dunes between the town of Guane and the village of Cortes (Pinar del Rio province). 相似文献
129.
130.
Substrate Degradation and Pressure Tolerance of Free-Living and Attached Bacterial Populations in the Intestines of Shallow-Water Fish
下载免费PDF全文
![点击此处可从《Applied microbiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
This report compares recovery of non-O1 Vibrio cholerae strains from seven California coastal sites during the winter and summer of 1983. A total of 41 identified and 27 presumptive nn-O1 V. cholerae strains were recovered from six of seven coastal sites in the summer. A 5-to 56-fold increase in the numbers of organisms isolated from different sites occurred in the summer months, when water temperatures were 1.9 to 5.1 degrees C higher. At the three sites where the highest levels of non-O1 V. cholerae were found, pollution, as measured by the total number of coliforms, exceeded the legal limit (less than 1,000 coliforms per 100 ml.). 相似文献