全文获取类型
收费全文 | 1754篇 |
免费 | 80篇 |
出版年
2021年 | 11篇 |
2020年 | 16篇 |
2019年 | 11篇 |
2018年 | 23篇 |
2017年 | 13篇 |
2016年 | 27篇 |
2015年 | 41篇 |
2014年 | 45篇 |
2013年 | 103篇 |
2012年 | 82篇 |
2011年 | 71篇 |
2010年 | 40篇 |
2009年 | 52篇 |
2008年 | 85篇 |
2007年 | 82篇 |
2006年 | 83篇 |
2005年 | 77篇 |
2004年 | 67篇 |
2003年 | 61篇 |
2002年 | 66篇 |
2001年 | 47篇 |
2000年 | 59篇 |
1999年 | 55篇 |
1998年 | 23篇 |
1997年 | 11篇 |
1996年 | 13篇 |
1995年 | 17篇 |
1994年 | 19篇 |
1993年 | 12篇 |
1992年 | 60篇 |
1991年 | 40篇 |
1990年 | 24篇 |
1989年 | 33篇 |
1988年 | 45篇 |
1987年 | 40篇 |
1986年 | 23篇 |
1985年 | 25篇 |
1984年 | 20篇 |
1983年 | 24篇 |
1981年 | 13篇 |
1980年 | 9篇 |
1979年 | 24篇 |
1976年 | 11篇 |
1975年 | 10篇 |
1974年 | 13篇 |
1973年 | 11篇 |
1972年 | 12篇 |
1971年 | 10篇 |
1970年 | 13篇 |
1968年 | 13篇 |
排序方式: 共有1834条查询结果,搜索用时 531 毫秒
151.
Synthesis of a core heptasaccharide asparagine N4-[alpha-D-mannopyranosyl-(1 --> 6)-[(alpha-D-mannopyranosyl)-(1 --> 3)]-[(2-acetamido-2-deoxy-beta-D-glucopyranosyl)-(1 --> 2)]-(beta-D-mannopyranosyl)-(1 --> 4)-(2-acetamido-2-deoxy-beta-D-glucopyranosyl)-(1 --> 4)-[(alpha-L-fucopyranosyl)-(1 --> 6)]-2-acetamido-2-deoxy-beta-D-glucopyranosyl]-L-asparagine (1a) found from CHO glycosylation mutant cell LEC 14 is described. The structure of 1a is highly novel in terms of the presence of an extra GlcNAc residue linked to the 2-position of beta-linked mannose. The synthesis was performed using p-methoxybenzyl-assisted intramolecular aglycon delivery as the key transformation. 4,6-O-TIDPS-protected thiomannoside methyl 2-O-p-methoxybenzyl-4,6-O-(1,1,3,3-tetraisopropyl)disiloxanylid ene-3-O-trimethylsilyl-1-thio-alpha-D-mannopyranoside was adopted for this particular purpose, which afforded beta-mannoside p-methoxyphenyl 2,3-O-(p-methoxybenzylidene)-4,6-O-(1,1,3,3-tetraisopropyl)+ ++disiloxanylidene-beta-D-mannopyranosyl-(1 --> 4)-3,6-di-O-benzyl-2-deoxy-2-phthalimido-beta-D-glucopyranoside stereoselectively in 75% yield. 相似文献
152.
Ando T Tatsuzawa F Saito N Takahashi M Tsunashima Y Numajir H Watanabe H Kokubun H Hara R Seki H Hashimoto G 《Phytochemistry》2000,54(5):495-501
In order to resolve a conflict between previous papers regarding the floral anthocyanins of red flowers of Petunia exserta, a naturally occurring species, the HPLC profile of this species was compared with that of commercial red garden petunias. Both HPLC profiles extremely superficially resemble each other in terms of relative amounts and retention times of the major anthocyanins. However, co-elution on HPLC of the mixed sample resulted in clear separation of the components. Three major anthocyanins in red petunias were determined to be cyanidin 3-sophoroside, cyanidin 3-glucoside and peonidin 3-glucoside, which exhibited similar behaviors on HPLC to delphinidin 3-glucoside. delphinidin-3-rutinoside and petunidin 3-rutinoside, respectively, the major floral anthocyanins of P. exserta. 相似文献
153.
Mambule C Ando Y Anan I Holmgren G Sandgren O Stigbrandt T Tashima K Suhr OB 《Biochimica et biophysica acta》2000,1474(3):331-336
The mechanism behind amyloid formation is unknown in all types of amyloidosis. Several substances can enhance amyloid formation in animal experiments. To induce secondary systemic amyloid (AA-type amyloid) formation, we injected silver nitrate into mice together with either amyloid fibrils obtained from patients with familial polyneuropathy (FAP) type I or polyethylene glycol (PEG). Mice injected with silver nitrate only served as controls. Amyloid deposits were detectable at day 3 in animals injected with amyloid fibrils and in those injected with PEG, whereas in control mice, deposits were not noted before day 12. Our results indicate that amyloid fibrils from FAP patients and even a non-sulfate containing polysaccharide (PEG) have the potential to act as amyloid-enhancing factors. 相似文献
154.
Characterization of p-chloroamphetamine-induced penile erection and ejaculation in anesthetized rats
Yonezawa A Watanabe C Ando R Furuta S Sakurada S Yoshimura H Iwanaga T Kimura Y 《Life sciences》2000,67(25):3031-3039
Methodological shortcomings present in elicitation of male sexual reflexes in anesthetized animals. The present study has demonstrated, however, that intraperitoneal (i.p.) injection of p-chloroamphetamine (PCA), an indirect serotonin (5-HT) agonist, elicited simultaneously both penile erection and ejaculation in anesthetized rats. PCA (2.5-10.0 mg/kg, i.p.) caused an intermittent cluster of genital responses consisting of penile erection, glans erections, and penile cups, which closely resembles the response observed during the ex copula tests in unanesthetized rats. Measurements of intracavernous penile pressure showed that rhythmic changes in penile pressure were produced by PCA, together with glans erections and penile cups. PCA also caused a frequent ejaculations and the weighing of ejaculate accumulated over 0.5 hr was increased in a bell-shaped pattern, and the maximum effect was observed at 5.0 mg/kg. Pretreatment with p-chlorophenylalanine, a serotonin (5-HT)-synthesis inhibitor, significantly inhibited the expression of PCA-induced penile erection and ejaculation, while acute spinal transection at thoracic level did not affect the sexual responses. These results indicate that PCA-induced penile erection and ejaculation in anesthetized rats are mainly produced by the release of 5-HT, which is limited to the lower spinal cord and/or the peripheral sites. Furthermore, the sexual responses can be easily and reliably elicited by administration of PCA, which may be useful for the study of the mechanisms underlying male sexual functions. 相似文献
155.
The concentrations of cadmium and other metal ions in selected organs, urine, and blood of female rats were measured after
exposure to cadmium chloride through their diet or by oral or intravenous administration. The hematological and urinary variations
were followed for 4 wk.
Body weight gain and the weights of livers and kidneys from all treated groups were not significantly different from the controls.
No gross morphological changes were observed in any of the tissues studied at necropsy.
The accumulation of cadmium occurred in the liver and kidney. The zinc levels in these organs were elevated relative to controls,
in all treated groups regardless of dose and exposure route. Copper was elevated in the liver, kidney, bone, and blood of
animals subject to intravenous administration of cadmium. Hepatic iron was decreased in the dietary and orally treated groups,
but was not affected in the intravenous study group. The level of magnesium in kidney was increased for all exposure routes,
but that of liver was increased only in the intravenously injected groups. The changes in the concentrations of sodium, potassium,
calcium, and phosphorus did not follow a specific pattern and varied from organ to organ, depending on the exposure route.
The discussion includes a relationship between tissue injury and the alteration of tissue essential element concentrations. 相似文献
156.
Using a strain of Candida krusei IA-1 isolated from commercial Japanese sake lees, the effects of carbon on the lag phase and logarithmic growth phase were investigated in repeated batch cultivation. The lag phase was about 1 h shorter with the addition of 2%w/v of activated carbon to fresh medium. The free cell concentration was approximately 108 cells/ml in the presence, but only 105 cells/ml without addition. ©: Rapid Science Ltd. 1998 相似文献
157.
Functional and Physical Interaction between Rad24 and Rfc5 in the Yeast Checkpoint Pathways 总被引:17,自引:8,他引:9
下载免费PDF全文
![点击此处可从《Molecular and cellular biology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Toshiyasu Shimomura Seiko Ando Kunihiro Matsumoto Katsunori Sugimoto 《Molecular and cellular biology》1998,18(9):5485-5491
The RFC5 gene encodes a small subunit of replication factor C (RFC) complex in Saccharomyces cerevisiae and has been shown to be required for the checkpoints which respond to replication block and DNA damage. Here we describe the isolation of RAD24, known to play a role in the DNA damage checkpoint, as a dosage-dependent suppressor of rfc5-1. RAD24 overexpression suppresses the sensitivity of rfc5-1 cells to DNA-damaging agents and the defect in DNA damage-induced Rad53 phosphorylation. Rad24, like Rfc5, is required for the regulation of Rad53 phosphorylation in response to DNA damage. The Rad24 protein, which is structurally related to the RFC subunits, interacts physically with RFC subunits Rfc2 and Rfc5 and cosediments with Rfc5. Although the rad24Δ mutation alone does not cause a defect in the replication block checkpoint, it does enhance the defect in rfc5-1 mutants. Furthermore, overexpression of RAD24 suppresses the rfc5-1 defect in the replication block checkpoint. Taken together, our results demonstrate a physical and functional interaction between Rad24 and Rfc5 in the checkpoint pathways. 相似文献
158.
Mika Baba Takuro Shimbo Masaru Horio Masahiko Ando Yoshinari Yasuda Yasuhiro Komatsu Katsunori Masuda Seiichi Matsuo Shoichi Maruyama 《PloS one》2015,10(6)
Background
Chronic kidney disease is an important concern in preventive medicine, but the rate of decline in renal function in healthy population is not well defined. The purpose of this study was to determine reference values for the estimated glomerular filtration rate (eGFR) and rate of decline of eGFR in healthy subjects and to evaluate factors associated with this decline using a large cohort in Japan.Methods
Retrospective cross-sectional and longitudinal studies were performed with healthy subjects aged ≥18 years old who received a medical checkup. Reference values for eGFR were obtained using a nonparametric method and those for decline of eGFR were calculated by mixed model analysis. Relationships of eGFR decline rate with baseline variables were examined using a linear least-squares method.Results
In the cross-sectional study, reference values for eGFR were obtained by gender and age in 72,521 healthy subjects. The mean (±SD) eGFR was 83.7±14.7ml/min/1.73m2. In the longitudinal study, reference values for eGFR decline rate were obtained by gender, age, and renal stage in 45,586 healthy subjects. In the same renal stage, there was little difference in the rate of decline regardless of age. The decline in eGFR depended on the renal stage and was strongly related to baseline eGFR, with a faster decline with a higher baseline eGFR and a slower decline with a lower baseline eGFR. The mean (±SD) eGFR decline rate was ‒1.07±0.42ml/min/1.73m2/year (‒1.29±0.41%/year) in subjects with a mean eGFR of 81.5±11.6ml/min/1.73m2.Conclusions
The present study clarified for the first time the reference values for the rate of eGFR decline stratified by gender, age, and renal stage in healthy subjects. The rate of eGFR decline depended mainly on baseline eGFR, but not on age, with a slower decline with a lower baseline eGFR. 相似文献159.
Masao Takahashi Susumu Miyazaki Masahiro Myojo Daigo Sawaki Hiroshi Iwata Arihiro Kiyosue Yasutomi Higashikuni Tomofumi Tanaka Daishi Fujita Jiro Ando Hideo Fujita Yasunobu Hirata Issei Komuro 《PloS one》2015,10(3)
Objectives
This study aimed to assess the relation between stent edge restenosis (SER) and the distance from the stent edge to the residual plaque using quantitative intravascular ultrasound.Background
Although percutaneous coronary intervention with drug-eluting stents has improved SER rates, determining an appropriate stent edge landing zone can be challenging in cases of diffuse plaque lesions. It is known that edge vascular response can occur within 2 mm from the edge of a bare metal stent, but the distance to the adjacent plaque has not been evaluated for drug-eluting stents.Methods
A total of 97 proximal residual plaque lesions (plaque burden [PB] >40%) treated with everolimus-eluting stents were retrospectively evaluated to determine the distance from the stent edge to the residual plaque.Results
The SER group had significantly higher PB (59.1 ± 6.1% vs. 51.9 ± 9.1% for non-SER; P = 0.04). Higher PB was associated with SER, with the cutoff value of 54.74% determined using receiver operating characteristic (ROC) curve analysis. At this cutoff value of PB, the distance from the stent edge to the lesion was significantly associated with SER (odds ratio = 2.05, P = 0.035). The corresponding area under the ROC curve was 0.725, and the cutoff distance value for predicting SER was 1.0 mm.Conclusion
An interval less than 1 mm from the proximal stent edge to the nearest point with the determined PB cutoff value of 54.74% was significantly associated with SER in patients with residual plaque lesions. 相似文献160.
Takanobu Nagata Yoshinari Yasuda Masahiko Ando Tomoko Abe Takayuki Katsuno Sawako Kato Naotake Tsuboi Seiichi Matsuo Shoichi Maruyama 《PloS one》2015,10(6)