全文获取类型
收费全文 | 3636篇 |
免费 | 241篇 |
国内免费 | 1篇 |
出版年
2023年 | 8篇 |
2022年 | 16篇 |
2021年 | 44篇 |
2020年 | 20篇 |
2019年 | 43篇 |
2018年 | 58篇 |
2017年 | 44篇 |
2016年 | 68篇 |
2015年 | 113篇 |
2014年 | 148篇 |
2013年 | 231篇 |
2012年 | 214篇 |
2011年 | 245篇 |
2010年 | 141篇 |
2009年 | 139篇 |
2008年 | 236篇 |
2007年 | 237篇 |
2006年 | 219篇 |
2005年 | 218篇 |
2004年 | 222篇 |
2003年 | 223篇 |
2002年 | 203篇 |
2001年 | 70篇 |
2000年 | 93篇 |
1999年 | 76篇 |
1998年 | 48篇 |
1997年 | 36篇 |
1996年 | 23篇 |
1995年 | 27篇 |
1994年 | 32篇 |
1993年 | 26篇 |
1992年 | 40篇 |
1991年 | 49篇 |
1990年 | 33篇 |
1989年 | 33篇 |
1988年 | 37篇 |
1987年 | 31篇 |
1986年 | 12篇 |
1985年 | 21篇 |
1984年 | 8篇 |
1983年 | 12篇 |
1982年 | 14篇 |
1981年 | 12篇 |
1980年 | 8篇 |
1979年 | 7篇 |
1975年 | 4篇 |
1974年 | 5篇 |
1973年 | 3篇 |
1972年 | 5篇 |
1966年 | 3篇 |
排序方式: 共有3878条查询结果,搜索用时 875 毫秒
1.
Kenji Tsuji Shinji KitamuraHirofumi Makino 《Biochemical and biophysical research communications》2014
The kidneys are exposed to hypoxic conditions during development. Hypoxia-inducible factor (HIF), an important mediator of the response to hypoxia, is believed to have an important role in development. However, the relationship between HIF and branching morphogenesis has not been elucidated clearly. 相似文献
2.
S Ikei M Ogawa T Beppu C Ohara K Sakamoto H Sameshima H Arakawa Y Yamaguchi T Yamanaka S Kudo 《Cytokine》1992,4(6):581-584
In an attempt to investigate the interaction between the changes of cytokines and acute phase reactants after transcatheter arterial chemoembolization therapy (TACE), the levels of interleukin 6 (IL-6), interleukin 8 (IL-8), C-reactive protein (CRP) and pancreatic secretory trypsin inhibitor (PSTI) in the blood of patients with unresectable hepatocellular carcinoma (HCC) were measured. Before the therapy, serum IL-6 and plasma IL-8 levels were detectable in 77.8% and 28.5%, respectively, of patients with HCC. Levels of serum IL-6 and plasma IL-8 increased after TACE and reached a peak on day 3 in all patients (18/18) and in 87.5% of patients (12/14), respectively. Both blood levels of IL-6 and IL-8 reached a peak earlier than those of CRP and PSTI did after the therapy. When the maximal values of IL-6 were compared with those of CRP and PSTI, there were significant positive correlations (r = 0.63, P < 0.01 and r = 0.81, P < 0.01, respectively). Similarly, comparisons of the maximal values of IL-8 with those of CRP and PSTI gave a significant correlation (r = 0.68, P < 0.01 and r = 0.67, P < 0.05, respectively). However, no significant correlation was found between the elevation of IL-6 and IL-8. 相似文献
3.
Hideaki Naoe Tatsuyuki Chiyoda Jo Ishizawa Kenta Masuda Hideyuki Saya Shinji Kuninaka 《Biochemical and biophysical research communications》2013,430(2):757-762
Differentiation of placental trophoblast stem (TS) cells to trophoblast giant (TG) cells is accompanied by transition from a mitotic cell cycle to an endocycle. Here, we report that Cdh1, a regulator of the anaphase-promoting complex/cyclosome (APC/C), negatively regulates mitotic entry upon the mitotic/endocycle transition. TS cells derived from homozygous Cdh1 gene-trapped (Cdh1GT/GT) murine embryos accumulated mitotic cyclins and precociously entered mitosis after induction of TS cell differentiation, indicating that Cdh1 is required for the switch from mitosis to the endocycle. Furthermore, the Cdh1GT/GT TS cells and placenta showed aberrant expression of placental differentiation markers. These data highlight an important role of Cdh1 in the G2/M transition during placental differentiation. 相似文献
4.
Gelation Phenomena Induced by Alkali-alcohol Treatment of 7S and 11S Components in Soybean Globulins
Transparent gels containing about 2% protein were obtained by mixing alkaline dope solution of 7S or 11S soybean proteins with alcohol. The 7S component showed the ability to form a stronger gel than the 11S. This phenomenon depended on pH and alcohol concentration. In 66 % ethanol, the viscosity of the 7S and 11S reached maxima at pH 11.4 and 11.2, respectively. Above these pH levels where further unfolding and dissociation into subunits of the protein molecules occur, the viscosity decreased rather. The effectiveness of alcohol to increase viscosity increased in the order; n-butanol < tert-butanol < n-propanol < iso-propanol < ethanol < methanol. Alcohols having minor hydrophobicity were more effective for increasing viscosity, but ethylene glycol was ineffective. The addition of NaCl or 2-mercaptoethanol to ethanol-mixed alkaline dope solutions resulted in the remarkable increment of the viscosity, especially for the 7S. 相似文献
5.
Mikihiko Naito Ichiro Kudo Yukiko Mukai-Sato Susumu Tsushima Hiroaki Nomura Shoshichi Nojima Keizo Inoue 《Cancer immunology, immunotherapy : CII》1987,24(2):158-164
Summary Liposomes composed of chemically synthesized glyceroglycolipids, such as 1,2-dipalmityl-[-cellobiosyl-(1 3)]-glycerol (Cel-DAG), 1,2-dipalmityl-[-lactosyl-(1 3)]-glycerol, or 1,2-dipalmityl-[-maltosyl-(1 3)]-glycerol, were found to enhance protective immunity against transplantable tumor cells (sarcoma 180) in ICR mice. Peritoneal exudate cells prepared from mice treated in vivo with Cel-DAG showed cytostatic activity in vitro against the mouse leukemia cell line, EL-4. Adherent cells separated from this preparation showed similar activity. Peritoneal cells from polypeptone-injected mice acquired appreciable cytostatic activity when incubated in vitro in the presence of glyceroglycolipid liposomes. The adherent cell fraction alone showed rather weak cytostatic activity when pretreated with the glyceroglycolipids, and full activity was restored by supplementing with the nonadherent cell fraction. The ability of glycolipids to induce tumoricidal effects was affected by cholesterol content: with increasing cholesterol content, the activities decreased. Cholesterol-free glycolipid liposomes were taken more efficiently by macrophages than cholesterol-containing liposomes. Cholersterol modifies the surface property of glyceroglycolipid liposomes. Activation of macrophages is responsible for enhancement of protective immunity against tumor cells by injection of these glycolipids in vivo.This work was supported in part by Grants-in-Aid (Nos. 58010010, and 59870076) for Scientific Research from the Ministry of Education, Science and Culture of Japan 相似文献
6.
The medium of 12-day-old culturs of tobacco cells (Nicotianatabacum L., var Xanthi; line XD-6S) contain c.a. 160mg/literof protein, of which 14% of the constituent ami no acids werefound to be hydroxyproline. By sequential column chromatographiesand CsCl density-gradient centrifugation, a basic hydroxyproline-richglycoprotein was purified from the medium and found to havean amino acid composition typical of extensin; with a high levelof hydroxyproline (33mole%), tyrosine (13%), and lysine (14%).The glycoprotein contained 42% (w/w) of sugars, among whicharabinose was the major component (85%). The proportion of thisextensin in the proteins in the culture medium was estimatedto be much higher than that of arabino-galactan protein (about5 times higher) on a protein basis, with extensin comprisingbetween 25% and 41%, and probably about 37% of the proteinsin the medium. (Received September 19, 1988; Accepted December 26, 1988) 相似文献
7.
M Naito H Utsumi M Umeda I Kudo K Takeshita A Hamada S Nojima K Inoue 《Biochimica et biophysica acta》1989,985(2):147-152
We previously reported that glyceroglycolipid liposomes without cholesterol activated mouse peritoneal macrophages in vivo and in vitro, whereas glyceroglycolipid liposomes containing equimolar cholesterol did not. In order to characterize the properties of the glyceroglycolipid membranes, ESR spectroscopic studies were carried out with an acyl spin-labeled galactosyl ceramide (SL-GC) or a headgroup spin-labeled phospholipid (SL-6-DPPA) in 1,2-dipalmitoyl[beta-cellobiosyl-(1'---3)]glycerol (Cel-DAG) liposomal membranes. The ESR spectrum of the SL-GC in the Cel-DAG liposomes at 37 degrees C was a single broad line, indicating that the SL-GC molecules were excluded almost completely from Cel-DAG domains and formed clusters in the membranes. The spectrum of SL-6-DPPA in the Cel-DAG liposomes at 37 degrees C showed broad resonance lines with the central peak being the highest, while that at 60 degrees gave narrow lines with the low-field peak being the highest. This observation and rotational correlation time analysis showed that the molecular motions of spin-label moiety of the SL-6-DPPA were extremely restricted at 37 degrees C but not above Tc. These results suggest that below Tc the Cel-DAG molecules are packed tightly and restricted in motion in the membrane. Incorporation of cholesterol into the Cel-DAG liposomal membranes gave (1) the spectra of the SL-GC triplet, and (2) the spectra of the SL-6-DPPA narrow resonance with the low-field peak being the highest. These results suggest that cholesterol disturbs the rigid-packed structure of the Cel-DAG membrane and increases the molecular motions of the Cel-DAG. The DSC analysis of Cel-DAG with and without cholesterol agreed well to the results of the ESR technique. Thus we assume that peritoneal macrophages recognize the rigid-packed carbohydrate residues which are restricted in motion on the Cel-DAG membranes. 相似文献
8.
Shinji Fukata Toshiaki Fukatsu Tetsuro Nagasaka Noboru Ohiwa Yoshiharu Nara Nobuo Nakashima Mitsuko Sobue Jun Takeuchi 《The Histochemical journal》1989,21(12):707-714
Summary The immunohistochemical localization of large proteoglycan and small proteoglycan was observed, using antibodies 2B1 and 6B6 (Sobueet al., 1988, 1989a), in fetal and adult pancreas and biliary system as well as in tumour tissues, obtained from 11 autopsies and 74 biopsies. The distribution of chondroitin 4- and 6-sulphate side chains, type I and IV collagen and elastin were also studied. In adult pancreas and all the biliary tracts examined, periductal fibrous tissues consisted mainly of dermatan sulphate small proteoglycan with networks of fibrous elements, which were composed of large proteoglycan, elastin, type I collagen and type IV collagen. In the interstitial components of cystadenoma of pancreas and biliary duct carcinoma, similar small proteoglycan-rich components were relatively abundant, although large proteoglycan was present in much larger amounts than that in non-neoplastic adult tissues. In some cholangiomas, the extra-and intracellular hyaline globules formed by the carcinoma cells were found to contain chondroitin sulphate large proteoglycan, laminin and fibronectin.The distribution of proteoglycans was observed to be different in the arterial walls of the interlobular tissues of the adult and the fetal pancreas. The biological significance of large and small proteoglycans in the interstitial connective tissues was discussed. 相似文献
9.
Structure and pre-B lymphocyte restricted expression of the VpreB in humans and conservation of its structure in other mammalian species. 总被引:11,自引:1,他引:10
DNA from several mammals, including humans, was found to contain one or more restriction enzyme digested DNA fragments which hybridized to the mouse VpreB gene under stringencies demonstrating at least 70% nucleotide sequence homologies, indicating that the VpreB locus may be widespread and highly conserved among mammals. A human VpreB genomic clone was isolated and sequenced. Two exons and the intervening intron are spaced almost identically as in the mouse VpreB1 gene, and show 76% sequence homology to the mouse gene. As in the mouse VpreB1 gene, the 5' end of the human VpreB gene contains characteristic features of Ig domains, while the 3' end is Ig non-related. This 3' Ig non-related structure of the VpreB gene(s) may, therefore, have existed before the speciation of humans and mice over 65 million years ago. Sequences encoding the entire putative second framework region and a stretch in the third framework region are identical in human and mouse VpreB. the human VpreB gene appears to be selectively expressed in human pre-B cell lines as an 0.85 kb poly(A)+ RNA. Its expression promises to be a useful marker for the detection of normal and malignant human pre-B lymphocytes. 相似文献
10.
Localization of cytochrome P-450 in the colonic mucosa of 3-methylcholanthrene-pretreated and untreated rats An immunohistochemical study 总被引:1,自引:0,他引:1
Dr. Shinji Tamura Sumio Kawata Mitsuhiro Okamoto Seiichiro Tarui 《Cell and tissue research》1988,252(2):397-401
Summary Immunohistochemical localization of cytochrome P-450 in the colonic mucosa of 3-methylcholanthrene-pretreated and untreated rats was studied by indirect fluorescent antibody staining technique. A polyclonal antibody for cytochrome P-450MC purified from hepatic microsomes of 3-methylcholanthrene-pretreated rats was used for this experiment. A strong immunofluorescence was found to be localized in the cytoplasm of the surface epithelium of the mucosa in the colon of 3-methylcholanthrene-pretreated rats. A faint immunofluorescence was also observed in the epithelium of untreated rats. 7-Ethoxycoumarin O-deethylase activity of colonic microsomes was significantly enhanced by 3-methylcholanthrene-pretreatment in parallel with an increase in the intensity of immunostaining for cytochrome P-450MC in Western blotting analysis. This is the first report on the localization of cytochrome P-450 in the colonic mucosa. 相似文献