全文获取类型
收费全文 | 737篇 |
免费 | 46篇 |
专业分类
783篇 |
出版年
2021年 | 12篇 |
2018年 | 12篇 |
2017年 | 8篇 |
2016年 | 10篇 |
2015年 | 14篇 |
2014年 | 31篇 |
2013年 | 46篇 |
2012年 | 37篇 |
2011年 | 31篇 |
2010年 | 28篇 |
2009年 | 21篇 |
2008年 | 33篇 |
2007年 | 43篇 |
2006年 | 30篇 |
2005年 | 30篇 |
2004年 | 32篇 |
2003年 | 34篇 |
2002年 | 37篇 |
2001年 | 25篇 |
2000年 | 24篇 |
1999年 | 21篇 |
1998年 | 13篇 |
1997年 | 10篇 |
1996年 | 11篇 |
1995年 | 7篇 |
1994年 | 10篇 |
1993年 | 12篇 |
1992年 | 9篇 |
1991年 | 11篇 |
1990年 | 9篇 |
1989年 | 12篇 |
1988年 | 10篇 |
1987年 | 9篇 |
1986年 | 8篇 |
1985年 | 7篇 |
1984年 | 7篇 |
1983年 | 5篇 |
1982年 | 6篇 |
1981年 | 7篇 |
1980年 | 9篇 |
1978年 | 5篇 |
1977年 | 3篇 |
1974年 | 4篇 |
1973年 | 4篇 |
1972年 | 3篇 |
1971年 | 5篇 |
1970年 | 3篇 |
1968年 | 4篇 |
1967年 | 4篇 |
1966年 | 4篇 |
排序方式: 共有783条查询结果,搜索用时 0 毫秒
41.
Takahiro Shiga Yoshifumi Kimira Hiroshi Mano Tetsunori Kawata Tadahiro Tadokoro Tsukasa Suzuki 《Bioscience, biotechnology, and biochemistry》2016,80(3):510-513
Vitamin B12 deficiency is a risk factor for bone disorders via mechanisms not fully understood. In this study, an increase in serum inorganic phosphorus (Pi) concentrations was associated with a vitamin B12 deficiency. Napi2a, a renal cotransporter for Pi reabsorption, accumulated on plasma membranes in a vitamin B12 deficiency suggests that vitamin B12 plays an important role in Pi homeostasis. 相似文献
42.
In the present study, we examined the effects of four kinds of cysteine protease inhibitors (E64, E64d, leupeptin, and ALLN) on the in vitro asexual growth of Babesia bovis. Of these, only the lipophilic inhibitors, E64d and ALLN, were found to effectively inhibit the growth of B. bovis. In further experiments, E64d, but not ALLN, significantly suppressed the parasite’s invasion of host erythrocytes, while both chemicals, especially ALLN, inhibited the parasite’s replication within the infected erythrocytes. These data suggested the presence of cysteine protease(s) derived from B. bovis, in which the protease(s) would play important roles in the erythrocyte invasion and/or replication processes of the parasite. 相似文献
43.
Enamel matrix derivative is a potent inhibitor of breast cancer cell attachment to bone 总被引:2,自引:0,他引:2
This study examined whether enamel matrix derivative (EMD) inhibits the adhesion of cancer cells to bone. A typical breast cancer cell line, MCF-7, was used. Conditioned human osteosarcoma cell (Saos-2) medium was used as extracellular bone matrix (ECBM) to measure cell attachment. MCF-7 cells were incubated on ECBM-coated culture plates with or without soluble EMD, Arg-Gly-Asp (RGD) sequence blocking peptides, recombinant bone sialoprotein (rBSP), or specific integrin antibodies, and the attached cells were quantified using toluidine blue staining. EMD markedly reduced the attachment of MCF-7 cells to ECBM in a dose-dependent manner. An RGD peptide (GRGDSP) and recombinant BSP inhibited cell attachment to the same degree as EMD. Similarly, anti-alphavbeta3 integrin antibody strongly reduced cell attachment, whereas anti-alphavbeta5 and anti-beta1 integrin antibodies had less marked effects on cell attachment. These results show that EMD inhibits MCF-7 cell attachment to a bone matrix and that it might be useful as an anti-adhesive agent for breast cancer cells to bone in vivo. 相似文献
44.
Murai T Mohamed M Bernard H Mahedi PA Saburi R Higashi S 《Primates; journal of primatology》2007,48(2):117-121
Successful or unsuccessful female transfers were observed seven times during a 32-month field study of proboscis monkeys (Nasalis larvatus) inhabiting a riverine forest along a tributary of the Kinabatangan River, Sabah, Malaysia. In all cases, the females voluntarily
left their own groups and immediately joined with another one. When adult females tried to shift to other groups, adult males
called them back to their own groups, but appeared to be indifferent to subadult females. When the adult females returned,
the males never attacked the females physically, but instead often emitted herding sounds to them. One subadult female was
repelled by a resident adult female. When one adult female transferred into a new one-male group, she left her behind son
in an all-male group. The number of females often fluctuated in most study groups, with this fluctuation being more prominent
among subadult females than adult females. It is likely that female transfer in proboscis monkeys is not a rare occurrence
and that it is especially common among sub-adult females. 相似文献
45.
H Saito J Ozaki J Yasuda M Kurokawa T Tomita Y Okubo M Tanaka S Nakagawa 《Japanese journal of medical science & biology》1984,37(2):83-95
The utility of the Groupamatic MG50 system for quantitative expression of agglutination in terms of continuous response was studied. By use of the characteristics of the design of this system, in which the change in voltage reflects the degree of agglutination, a linear regression relationship between the log ratio of light flux obtained by transformation of the voltage and the log dilution factor of the serum was demonstrated. The availability of the parallel line assay method to the standardization of the blood grouping antisera was also described. 相似文献
46.
Mating pheromone-induced alteration of cell surface proteins in the heterobasidiomycetous yeast Tremella mesenterica. 下载免费PDF全文
T Miyakawa T Kadota Y Okubo T Hatano E Tsuchiya S Fukui 《Journal of bacteriology》1984,158(3):814-819
Mating pheromone-induced alteration of the cell surface proteins of haploid cells, presumed to play crucial roles in the specific cell-cell interactions during sexual conjugation of Tremella mesenterica , was investigated. Exposed surface proteins were revealed by lactoperoxidase-catalyzed iodination in combination with polyacrylamide gel electrophoresis and autoradiography. From comparison of the molecular species of 125I-labeled surface proteins of the vegetative and the gamete (mating pheromone-treated) cells of the two compatible mating types (ab and AB), it was suggested that a striking change in cell surface structure occurs during the differentiation; although labeled protein species of the vegetative cells of the two mating types were indistinguishable, several new species, both mating type specific and nonspecific, appeared in the gamete cells. Turnover of the labeled proteins of the vegetative cells was negligible, whereas that of the gamete cells was rapid with release of low-molecular-weight labeled proteins in the medium. A role for the labeled surface proteins of the gamete cells in the cell-cell interactions during sexual conjugation was suggested by the following: the surface changes were induced by mating pheromone; the labeled proteins were preferentially localized on the surface of the mating tube; the labeled species appeared sequentially during the differentiation; and mating type-specific species were present in both mating types. 相似文献
47.
Double antenna structure of chicken prolactin receptor deduced from the cDNA sequence. 总被引:14,自引:0,他引:14
M Tanaka K Maeda T Okubo K Nakashima 《Biochemical and biophysical research communications》1992,188(2):490-496
Chicken prolactin receptor (cPRLR) deciphered from the cDNA sequence showed a unique double antenna structure in its extracellular domain. The predicted cPRLR preprotein was composed of 831 amino acids and contained a signal peptide and a transmembrane region. The extracellular domain comprised 438 residues, and was divided into two tandemly repeated, highly homologous units, each of which corresponded to the extracellular domains of mammalian prolactin receptors. Both extracellular units of cPRLR possessed two structural features characteristic of the ligand binding units of cytokine/prolactin receptor family, namely two pairs of cysteine residues and a WSXWS motif. These findings strongly suggest that cPRLR contains two repeated ligand binding units, that is a double antenna structure. The cPRLR gene is expressed in a wide range of tissues of laying hen. 相似文献
48.
Karin Lindström Albert E. G. Kr. Von Dem Borne Michael E. Breimer Bertil Cedergren Yasuto Okubo Lennart Rydberg Susann Teneberg Bo E. Samuelsson 《Glycoconjugate journal》1992,9(6):325-329
A 12-week-old fetus and one 17-week-old fetus + placenta were obtained after spontaneous abortions from two women of blood group p. The 17-week-old fetus was dissected into intestine, liver, brain and residual tissue. Nonacid glycosphingolipid fractions were prepared from the tissues. Glycolipid characterization was carried out using thin layer chromatography immunostained with monoclonal antibodies and bacteria and by1H NMR spectroscopy and mass spectrometry. In the placental fraction substantial amounts of globotetraosylceramide (P-antigen) and globotriaosylceramide (Pk-antigen) were identified. In contrast, the fetuses contained only trace amounts of these structures, as revealed by immunostaining. These results indicate that the primary target for the antibodies of the anti-Tja serum is the placenta tissue, resulting in termination of the pregnancy. 相似文献
49.
50.
We examined whether short-term ascorbic acid deficiency induces oxidative stress in the retinas of young guinea pigs. Four-week-old guinea pigs were given a scorbutic diet (20 g/animal/day) with and without adequate ascorbic acid (400 mg/animal/day) in drinking water for 3 weeks. The serum concentrations of the reduced form of ascorbic acid and the oxidized form of ascorbic acid in the deficient group were 14.1 and 4.1%, respectively, of those in the adequate group. The retinal contents of the reduced form of ascorbic acid and the oxidized form of ascorbic acid in the deficient group were 6.4 and 27.3%, respectively, of those in the adequate group. The retinal content of thiobarbituric acid-reactive substances, an index of lipid peroxidation, was 1.9-fold higher in the deficient group than in the adequate group. Retinal reduced glutathione and vitamin E contents in the deficient group were 70.1 and 69.4%, respectively, of those in the adequate group. This ascorbic acid deficiency did not affect serum thiobarbituric acid-reactive substances and reduced glutathione concentrations but increased serum vitamin E concentration. These results indicate that short-term ascorbic acid deficiency induces oxidative stress in the retinas of young guinea pigs without disrupting systemic antioxidant status. 相似文献