全文获取类型
收费全文 | 1762篇 |
免费 | 92篇 |
出版年
2023年 | 35篇 |
2022年 | 20篇 |
2021年 | 34篇 |
2020年 | 38篇 |
2019年 | 24篇 |
2018年 | 72篇 |
2017年 | 66篇 |
2016年 | 80篇 |
2015年 | 53篇 |
2014年 | 56篇 |
2013年 | 126篇 |
2012年 | 131篇 |
2011年 | 137篇 |
2010年 | 77篇 |
2009年 | 53篇 |
2008年 | 91篇 |
2007年 | 111篇 |
2006年 | 93篇 |
2005年 | 82篇 |
2004年 | 85篇 |
2003年 | 98篇 |
2002年 | 89篇 |
2001年 | 35篇 |
2000年 | 44篇 |
1999年 | 19篇 |
1998年 | 8篇 |
1997年 | 6篇 |
1996年 | 5篇 |
1995年 | 3篇 |
1994年 | 5篇 |
1992年 | 6篇 |
1991年 | 4篇 |
1989年 | 2篇 |
1988年 | 5篇 |
1986年 | 2篇 |
1984年 | 4篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 4篇 |
1980年 | 3篇 |
1978年 | 2篇 |
1975年 | 7篇 |
1974年 | 4篇 |
1973年 | 4篇 |
1972年 | 2篇 |
1971年 | 3篇 |
1969年 | 2篇 |
1967年 | 2篇 |
1966年 | 2篇 |
1964年 | 2篇 |
排序方式: 共有1854条查询结果,搜索用时 15 毫秒
991.
Caksen H Tuncer O Ataş B Demirok A Unal O Ikbal M Odabaş D 《Genetic counseling (Geneva, Switzerland)》2003,14(3):343-348
The patient is a 12-year-old boy with a history of learning disability, growth retardation, and strabismus. Weight, height and head circumference were below the 3rd percentile. A café-au-lait spot, 1x1 cm a diameter, on the back region and pectus excavatum deformity were diagnosed. He had facial asymmetry, a broad nose, sparse eyebrows and eyelashes, a rudimentary frontal sinus, deviation of the nasal septum, and bilateral small maxillary bones. The left orbital fossa was also mildly rudimentary. On eye examination the movements of the left globe to the upward and lateral side were limited and internal strabismus was noted at this side. Visual acuity was 1/10, bilaterally. Bilateral choroid coloboma, glaucoma, vertical and horizontal nystagmus were diagnosed. Fundoscopic examination revealed bilateral optic atrophy and macular and paramacular granulation tissues on the left side. Intelligence quotient was 46. Electroencephalography revealed bilateral frontal slow-wave activity. Visual evoked potential revealed prolonged p100 wave latencies bilaterally. Magnetic resonance imaging of the brain demonstrated corpus callosum dysgenesis, bilateral subcortical heterotopia in the frontal lobes and subependymal heterotopia in the posterior horn of the left ventricle. Chromosomal analysis revealed a normal male karyotype, 46, XY. Although several cases of heterotopia in association with mental retardation, craniofacial dysmorphism, cerebral, and eye abnormalities have been described the combination of abnormalities diagnosed in our case has not previously been reported. We hypothesize that the combination of subcortical/subependymal heterotopia, corpus callosum dysgenesis, craniofacial dysmorphism, severe eye abnormalities, and growth-mental retardation may be a new syndrome. 相似文献
992.
Işman CA Gülpinar MA Kurtel H Alican I Yeğen BC 《Advances in physiology education》2003,27(1-4):53-61
The aim of the present study was to evaluate the strong or weak aspects of an interactive study module introduced during the "Cardiovascular and Respiratory Systems Subject Committee" in the second year of the medical program. Five study groups consisting of 25 students attended two-hour module sessions for six weeks with the same tutor. According to the module assessment questionnaire, the majority of the students assessed the module as excellent or good. The students reported that they had gained not only in knowledge but also in skills development. The general opinion of the students was that both the organization and the implementation of the module met their expectations. Nearly one-half of the students reported that their expectations with regard to the educational environment and the participation of students were fully met. The major weakness in this new educational trial appears to be assessment of the module. 相似文献
993.
In this research, acid phosphatase was purified and characterized from approximately 3000-year-old human bones from archeological excavations. Using anion exchange chromatography, two isoenzymes, TrACP and TsACP, were isolated from the bone. TrACP and TsACP were eluted separately, with a concentration gradient, from a CM-sepharose column. The resulting TrACP was further purified on a cellulose phosphate column. The activity was determined by using pNPP as substrate. Additionally, protein was determined by the Bradford and Coomassie Brilliant Blue method. The optimum pHs of TsACP and TrACP were 6 and 5, respectively. The optimum temperatures were 0 and 10 degrees C, respectively. Molecular weights were measured by gel filtration chromatography. The isoenzyme purity was checked with SDS-PAGE. Finally, the effects of sodium molybdate and tartrate on isoenzyme activity were determined. 相似文献
994.
The shape parameter of liposomes and DNA-lipid complexes determined by viscometry utilizing small sample volumes
下载免费PDF全文
![点击此处可从《Biophysical journal》网站下载免费的PDF全文](/ch/ext_images/free.gif)
A minicapillary viscometer utilizing <0.5 ml of sample at a volume fraction of <0.1% is described. The calculated a/b of DPPC/DPPG multilamellar liposome was 1.14 as prolate ellipsoids and a/b of dioleoylpropyltrimethyl ammonium methylsulfate-DNA complex at a charge ratio of 4:1 (+/-) was 3.7 as prolate ellipsoids or 4.9 as oblate ellipsoids. The deviation of shape from perfect sphere is thus expressed quantitatively in more than two significant figures. In these measurement, the necessary amount of DNA is <0.5 mg. 相似文献
995.
Membrane-bound aminopeptidase P (mAPP) is a highly specific exopeptidase that removes the N-terminal amino acid only from a peptide (three amino acids or longer) that has a prolyl residue in the second position. mAPP can inactivate bradykinin, a potent vasodilating and cardioprotective peptide hormone, by hydrolyzing the Arg(1)-Pro(2) bond. Studies on the rat have shown that the metabolism of bradykinin is an important physiological role of this enzyme. We report here the complete coding sequences for rat and mouse mAPP determined from mRNA isolated from lung tissue. Key structural features that determine post-translational processing and substrate recognition and catalysis were identified based on sequence homologies and the crystal structure of Escherichia coli aminopeptidase P complexed with Pro-Leu. The tissue-specific expression of mAPP was studied using the polymerase chain reaction. The mAPP gene is widely, but variably, expressed in adult tissues of the rat and mouse and in mouse embryos. 相似文献
996.
Gümüş F Pamuk I Ozden T Yildiz S Diril N Oksüzoglu E Gür S Ozkul A 《Journal of inorganic biochemistry》2003,94(3):255-262
In this study, six Pt(II) complexes bearing 5(6)-H or -CH(3)-2-phenyl or -(2'-pyridyl) or -mercaptomethylbenzimidazole ligands as 'carrier groups' were synthesized and characterized by elemental analysis, IR and (1)H-NMR spectra and evaluated for their preliminary in vitro cytotoxic activity to the human RD Rhabdomyosarcoma cell line and mutagenic properties in Salmonella typhimurium strains TA 98 and TA 100 in the absence of the S9 rat liver fraction. The preliminary test results showed that the complexes had slightly greater cytotoxic activity on the RD cell line at 1 microM concentration than cisplatin. Among the compounds tested for their mutagenicity, Pt(II) complexes of 2-(2'-pyridyl)- and 5(6)-methyl-2-(2'-pyridyl)benzimidazoles were found to be mutagenic. A comparative study of the MIC (minimum inhibitory concentration) values indicated that, in general, there were no differences between the poor antimicrobial activity values of the ligands and their Pt(II) complexes with respect to the tested microorganisms. These results suggest that the synthesized Pt(II) complexes should be considered for further antitumor activity studies. 相似文献
997.
Glucosides from Vitex agnus-castus 总被引:2,自引:0,他引:2
The methanolic extract of the flowering stems of Vitex agnus-castus yielded three new iridoids: 6'-O-foliamenthoylmussaenosidic acid (agnucastoside A), 6'-O-(6,7-dihydrofoliamenthoyl)mussaenosidic acid (agnucastoside B) and 7-O-trans-p-coumaroyl-6'-O-trans-caffeoyl-8-epiloganic acid (agnucastoside C) in addition to four known iridoids (aucubin, agnuside, mussaenosidic acid and 6'-O-p-hydroxybenzoylmussaenosidic acid) and one known phenylbutanone glucoside (myzodendrone). The structure elucidations were mainly done by spectroscopic methods (1D and 2D NMR spectra) and MS data interpretation. The purified compounds were tested for biological activities against various microorganisms and cancer cell lines. 相似文献
998.
Akan M Yildirim S Misirlioğlu A Ulusoy G Aköz T Avci G 《Plastic and reconstructive surgery》2003,111(7):2243-2249
In the art of plastic surgery, the reconstruction of tissue defects to obtain cosmetic and functional recovery is the major concern. Skin grafting is the most frequently used procedure for reconstructing defects of various size and anatomical localizations. On the other hand, donor-site problems associated with this invaluable procedure are inevitable. Various methods are used in the postoperative management of the partial-thickness donor site created during the harvest of a split-thickness skin graft. Each technique has the potential for complications of fluid loss, excessive pain, prolonged period of healing and immobilization, hypertrophic scarring, and undesirable pigmentation. Donor-site pain is probably the most disturbing complication in the early postoperative period. The aim of this article is to point out the significance of donor-site pain, which has not been emphasized thoroughly in the literature, and to introduce flap skin as a potential graft donor site for patients in whom reduction of donor-site morbidity is of primary concern. The principal goal of the technique described in this article is to eliminate donor-site pain by harvesting the graft from the flap that is insensate after the elevation. In 15 patients, the overlying skin of the flap that had been used for reconstructive purposes was used as the donor site (group I). In the remaining 23 patients, the posterolateral thigh was used as the donor site (group II). Donor-site discomfort was recorded during the first 8 days postoperatively using a visual analogue scale. To analyze the data, we used the Friedman test, Dunn's multiple comparison test, and Mann-Whitney U test. It was observed that the visual analogue scale of both of the groups showed a significant decrease within days (group I, p < 0.0001; group II, p < 0.0001). The mean pain scores were significantly lower in group I than in group II (p < 0.0001). When donor-site pain is of primary concern, this procedure provides uneventful and comfortable healing while avoiding postoperative pain in the donor site. For that reason, this technique might be used in appropriate cases to minimize donor-site pain. 相似文献
999.
1000.
Işik S Er E Soysal Y Imirzalioğlu N 《Plastic and reconstructive surgery》2003,111(1):275-82; discussion 283-5
Cyclosporine A, one of the most potent immunosuppressive drugs, mediates some of its immunosuppressive and nephrotoxic effects by enhancing transforming growth factor-beta secretion and receptor expression. In this experimental study, the effect of cyclosporine pretreatment of cultured dermal fibroblasts on xenogeneic tissue rejection after microimplantation beneath skin grafts was investigated. The effects of the site-specific immunosuppressive strategy on skin xenograft survival were tested. Because the skin is an immunological indicator of the rejection of composite tissue allografts, it was considered that this strategy could be used as a supportive therapy for composite tissue allotransplantation in the future. In the first stage of the study, fibroblast cultures obtained from skin biopsy samples from five rats were treated with different single doses of cyclosporine (100 to 3000 ng/ml), and transforming growth factor-beta levels were measured in culture supernatants after 72 hours. In the second stage, 60 Sprague-Dawley rats were divided into six groups, as follows. For group I (sham), only the standard grafting procedure was performed. For group II, after the standard grafting procedure, rats were treated with intraperitoneal injections of 30 mg/kg (n = 5) or 10 mg/kg (n = 5) cyclosporine for 10 days. For group III, cultured fibroblasts obtained from skin biopsy samples from rats were treated with 100 or 500 ng/ml cyclosporine, and the cells were collected by light trypsinization and centrifugation after 72 hours. After the standard skin grafting procedure, modified fibroblasts were implanted between the graft and the recipient bed with a Pasteur pipet. For group IV, the same procedures as for group III were performed and then rats were treated with 10 mg/kg cyclosporine, administered intraperitoneally, for 10 days. For group V, in addition to standard grafting, unmodified fibroblasts (not treated with cyclosporine) were implanted between the graft and the recipient bed. For group VI, the same procedures as for group V were performed and then rats were treated with 10 mg/kg cyclosporine, administered intraperitoneally, for 10 days. The rejection process was observed macroscopically, and statistical significance was determined with the Mann-Whitney test (p < 0.01). Graft survival times were significantly prolonged in groups III and IV, compared with groups I, II, V, and VI (p < 0.001). No difference between groups III and IV was observed. The novel finding of this investigation is that xenogeneic skin graft survival times could be prolonged with microimplantation of cyclosporine-treated cultured fibro-blasts. 相似文献