全文获取类型
收费全文 | 3439篇 |
免费 | 290篇 |
出版年
2023年 | 16篇 |
2021年 | 48篇 |
2020年 | 51篇 |
2019年 | 49篇 |
2018年 | 65篇 |
2017年 | 60篇 |
2016年 | 106篇 |
2015年 | 183篇 |
2014年 | 188篇 |
2013年 | 245篇 |
2012年 | 262篇 |
2011年 | 268篇 |
2010年 | 178篇 |
2009年 | 140篇 |
2008年 | 217篇 |
2007年 | 210篇 |
2006年 | 181篇 |
2005年 | 186篇 |
2004年 | 168篇 |
2003年 | 135篇 |
2002年 | 140篇 |
2001年 | 39篇 |
2000年 | 43篇 |
1999年 | 37篇 |
1998年 | 35篇 |
1997年 | 29篇 |
1996年 | 20篇 |
1995年 | 23篇 |
1994年 | 24篇 |
1993年 | 25篇 |
1992年 | 27篇 |
1991年 | 30篇 |
1990年 | 16篇 |
1989年 | 11篇 |
1988年 | 17篇 |
1987年 | 13篇 |
1985年 | 18篇 |
1984年 | 14篇 |
1983年 | 15篇 |
1982年 | 16篇 |
1981年 | 17篇 |
1980年 | 13篇 |
1979年 | 14篇 |
1977年 | 16篇 |
1976年 | 19篇 |
1974年 | 9篇 |
1971年 | 8篇 |
1968年 | 9篇 |
1967年 | 8篇 |
1964年 | 8篇 |
排序方式: 共有3729条查询结果,搜索用时 497 毫秒
1.
Sonia Coni Silvia Maria Serrao Zuleyha Nihan Yurtsever Laura Di Magno Rosa Bordone Camilla Bertani Valerio Licursi Zaira Ianniello Paola Infante Marta Moretti Marialaura Petroni Francesca Guerrieri Alessandro Fatica Alberto Macone Enrico De Smaele Lucia Di Marcotullio Giuseppe Giannini Marella Maroder Enzo Agostinelli Gianluca Canettieri 《Cell death & disease》2020,11(12)
2.
In the frog intestine, both in vitro and in vivo, experiments were carried out in order to increase knowledge of the mechanism of sugar exit across the basolateral membrane of the enterocyte. The frog intestine was chosen because it lacks crypt cells and, consequently, any external fluid circuit mechanism during sugar transport can be avoided. Therefore, the sugar concentration in the absorbate collected on the serosal side is likely to be similar to that present underneath the basolateral membrane of the enterocyte. Under this condition, cell and absorbate sugar concentrations are similar; yet there is a concomitant net transintestinal sugar transport. Moreover, in in vivo experiments a net transintestinal sugar transport takes place even against a concentration difference. These results suggest that sugar exit across the basolateral membrane is not simply due to a chemically facilitated diffusion. 相似文献
3.
4.
Rosemary Carpenter Cathie Martin Enrico S. Coen 《Molecular & general genetics : MGG》1987,207(1):82-89
Summary In Antirrhinum majus the transposable element Tam3 has been described at two unlinked loci pallida and nivea, both of which are required for the production of anthocyanin pigment in flowers. In each case the element is inserted in the promoter region and gives a variegated phenotype. We show that the rate of Tam3 excision at both loci is greatly affected by temperature, being approximately 1000-fold higher at 15°C compared with 25°C. Tam3 is also controlled by an unlinked gene Stabiliser, which considerably reduces excision rate. We show that the high degree of sensitivity to temperature and Stabiliser is an intrinsic property of Tam3 which is not shared by an unrelated element, Tam1. The Tam3 insertion at nivea gives rise to a series of alleles which confer reduced pigmentation, novel spatial patterns and changed instability. These are probably a result of imprecise excision and rearrangements of the Tam3 element. 相似文献
5.
A 1H NMR study of the peptide alamethicin, which forms voltage-gated ion channels in membranes, is described. The molecule was studied in methanol as a function of temperature and pH. A complete assignment of the spectra is given, including several stereospecific assignments. Alamethicin was found to have a structure substantially similar to the crystal although, in solution, the C-terminal dipeptide adopts a somewhat extended conformation. The overall conformation was insensitive to the ionization of the side chain of the only ionizable group, Glu-18. 相似文献
6.
Enrico Garaci Antonio Mastino Francesca Pica Cartesio Favalli 《Cancer immunology, immunotherapy : CII》1990,32(3):154-160
Summary A combination treatment with thymosin 1 (200 µg/kg) for 4 days, followed by a single injection of murine interferon / (3 × 104 international units/mouse), starting 2 days after cyclophosphamide treatment (200 mg/kg, single injection) demonstrated a dramatic and rapid disappearance of tumor burden in mice bearing Lewis lung carcinoma (3LL) tumor. The effectiveness of this new chemoimmunotherapy protocol was evident even on the long-term survival in a high percentage of animals, and was statistically significant when compared to treatment with the single agents in conjunction with chemotherapy or to chemotherapy itself. The same combination immunotherapy treatment strongly stimulated natural killer activity and cytotoxicity against autologus 3LL tumor cells in 3LL-tumor-bearing mice treated with cyclophosphamide, whereas treatments with each agent singly did not alter or only slightly modified the cytotoxic activity towards Yac-1 or 3LL target cells. Selective depletion with antibodies showed that killer cells stimulated by combination chemoimmunotherapy treatment bear phenotypic characteristics of asialo-GM1-positive cells. A histological study has shown a high number of infiltrating lymphoid cells in the tumors obtained from mice treated with combination chemoimmunotherapy. 相似文献
7.
This minireview makes an initial assessment of the progress made using anisotropy decay measurements for investigating the conformational changes and molecular dynamics in soluble systems. A critical analysis of available data is presented. The anisotropy decays of the tryptophan fluorescence of staphylococcal nuclease, adrenocorticotropin, melittin and of labeled transfer RNA were studied for investigating the functional conformational changes of these systems. The emissions of variously labeled immunoglobulins have been used to elucidate the conformations of these proteins before and after the binding of specific antibodies. Labeled myosin and its fragments have given information on the functional motions of the protein domains. The anisotropy decays of labeled and natural hemoglobin systems have been utilized for exploring the allosteric behavior of these molecules. The data suggest a wide applicability of this technique to the study of protein dynamics and conformational changes of macromolecules. 相似文献
8.
9.
M Fekadu J H Shaddock J W Sumner D W Sanderlin J C Knight J J Esposito G M Baer 《Journal of wildlife diseases》1991,27(4):681-684
Twenty nine skunks (Mephitis mephitis) were vaccinated orally with raccoon poxvirus (RCN) recombinants: 10 with a recombinant expressing the rabies virus glycoprotein (RCNRG), 10 with RCNRG mixed with a recombinant expressing the rabies virus nucleoprotein (RCNRN) and nine with RCN alone. Rabies virus neutralizing antibodies were detected in six of the 20 skunks; five skunks (three given RCNRG, two given a mixture of recombinants) survived a rabies challenge that was lethal for nine skunks vaccinated with RCN alone. 相似文献
10.