首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   3953篇
  免费   174篇
  国内免费   28篇
耳鼻咽喉   38篇
儿科学   75篇
妇产科学   20篇
基础医学   596篇
口腔科学   94篇
临床医学   221篇
内科学   1119篇
皮肤病学   160篇
神经病学   337篇
特种医学   77篇
外科学   567篇
综合类   17篇
预防医学   90篇
眼科学   71篇
药学   277篇
中国医学   11篇
肿瘤学   385篇
  2023年   31篇
  2022年   48篇
  2021年   72篇
  2020年   32篇
  2019年   60篇
  2018年   74篇
  2017年   56篇
  2016年   68篇
  2015年   57篇
  2014年   82篇
  2013年   123篇
  2012年   190篇
  2011年   257篇
  2010年   106篇
  2009年   123篇
  2008年   205篇
  2007年   214篇
  2006年   231篇
  2005年   196篇
  2004年   228篇
  2003年   212篇
  2002年   200篇
  2001年   85篇
  2000年   102篇
  1999年   83篇
  1998年   70篇
  1997年   58篇
  1996年   43篇
  1995年   35篇
  1994年   41篇
  1993年   34篇
  1992年   84篇
  1991年   57篇
  1990年   68篇
  1989年   59篇
  1988年   48篇
  1987年   54篇
  1986年   43篇
  1985年   60篇
  1984年   29篇
  1983年   36篇
  1982年   22篇
  1981年   17篇
  1980年   17篇
  1979年   29篇
  1978年   24篇
  1977年   16篇
  1976年   10篇
  1975年   12篇
  1969年   9篇
排序方式: 共有4155条查询结果,搜索用时 31 毫秒
91.
Purpose  The effects of reciprocal transplantation of meiosis-II chromosomes between senescent and young mouse oocytes were evaluated based on pre- and post-implantation development ability of resultant embryos. Methods  Karyoplasts including meiosis-II chromosomes of oocytes from senescent Rockefeller mouse/Ms-Rb(6, 15) females (10 to 12 months, age-related infertile mice) were transferred into cytoplasts of oocytes from young F1 females (3 to 5 months). Reconstructed oocytes were fertilized in vitro, and then the resultant embryos were cultured in vitro and transferred to recipient mice. Results  The reconstructed oocytes that consisted of aged-karyoplasts and young-cytoplasts showed significantly improved embryonic development (from 23.2% to 30.0%) and development to term (from 6.3% to 27.1%, P < 0.05) as compared with the oocytes reconstructed from young-karyoplasts and aged-cytoplasts. Conclusions  The present study showed successful rejuvenation for age-related infertility using transplantation of meiosis-II chromosomes in animal experimental models. Capsule Transplantation of meiosis-II chromosomes of senescent mouse oocytes into cytoplasts of young mouse oocytes improves subsequent embryonic and fetal development until birth.  相似文献   
92.
BACKGROUND/AIMS: The anti-cancerous effect on hepatocellular carcinoma of a newly established form of thermotherapy, which uses an implant heating system, was evaluated. As a new material for application in hyperthermia, the authors developed a powder type Mg-ferrite complex that produces heat under a relatively low-power magnetic field. METHODOLOGY: This material suspended in Lipiodol was injected into tumors on the backs of mice that consisted of human hepatocellular carcinoma cells. Hyperthermia was performed by directing a magnetic charge on tumor-bearing mice that contained the Mg-ferrite complex. The temperature of the tumor was kept at 42-43 degrees C, while the magnetic field power ranged from 50 to 80G. RESULTS: A 10-min hyperthermia treatment was insufficiently effective against tumor growth. Systemic injection of doxorubicin (ADM) before hyperthermia appeared to enhance the anti-cancerous effect, but the difference was little and did not reach a statistically significant level (repeated measure analysis of variance). The anticancerous effect of hyperthermia for 15 minutes, in contrast, was marked. The nodules had almost completely disappeared by the end of the experiment. CONCLUSIONS: In conclusion, it is suggested that hyperthermotherapy using this newly developed Mg-ferrite complex might become an option for low-invasive therapy for advanced hepatocellular carcinoma in humans.  相似文献   
93.
94.
95.
Li Y  Azuma A  Takahashi S  Usuki J  Matsuda K  Aoyama A  Kudoh S 《Chest》2002,122(6):2137-2145
BACKGROUND AND OBJECTIVE: Although the pathogenesis of interstitial pneumonia and pulmonary fibrosis are not well understood, it has been reported that inflammatory cells, especially neutrophils, and the injurious substances produced by them play important roles in the progression of interstitial pneumonia and subsequent fibrosis. Erythromycin and other 14-membered ring macrolides (14-MRMLs) have been reported to improve the survival of patients with diffuse panbronchiolitis by antineutrophil and several other anti-inflammatory mechanisms. The present study was undertaken to investigate the effects of 14-MRMLs on an experimental model of bleomycin-induced acute lung injury and subsequent fibrosis in mice. METHODS: Bleomycin was administered IV to ICR mice. At 28 days after bleomycin injection, fibrotic foci were histologically observed in left lung tissues, and hydroxyproline content in right lung tissues was chemically analyzed. The inhibitory effects of 14-MRMLs were assessed by overall comparison between control (normal saline solution [NS] alone), untreated (bleomycin alone), and treated (bleomycin plus 14-MRMLs) groups. For evaluation of early-phase inflammation, cell populations in BAL fluid and induction of messenger RNA (mRNA) of adhesion molecules (E-selectin, P-selectin, intercellular adhesion molecule 1 [ICAM-1], and vascular cell adhesion molecule 1 [VCAM-1]) in lung tissues were examined at 0 to 13 days after bleomycin treatment. These parameters were also compared with those for the control (NS alone), 14-MRML untreated (bleomycin alone), and 14-MRML pretreated (bleomycin plus 14-MRML pretreated) groups. RESULTS: Bleomycin-induced pulmonary fibrosis was inhibited by erythromycin and other 14-MRMLs on day 28 after bleomycin injection in ICR mice, especially those pretreated with 14-MRMLs. Hydroxyproline content in lung tissues was also decreased in the 14-MRML-pretreated groups. The number of neutrophils in BAL fluid significantly increased, with two peaks at 1 day and 9 days (from 6 to 11 days) after bleomycin administration. 14-MRMLs significantly inhibited both peaks of neutrophil infiltration into the airspace. Changes in mRNA expression of adhesion molecules (E-selectin, P-selectin, ICAM-1, VCAM-1) were associated with leukocyte migration into the airspace. 14-MRMLs clearly inhibited the induction of VCAM-1 mRNA, and tended to attenuate that of ICAM-1 mRNA, but inhibited the induction of neither E-selectin mRNA nor P-selectin mRNA. CONCLUSION: These findings indicate that attenuation of inflammatory cell migration into the airspace by 14-MRMLs, especially of neutrophils and macrophages, resulted in inhibition of lung injury and subsequent fibrosis. 14-MRMLs clearly attenuated the expression of VCAM-1 mRNA during the early phase of bleomycin-induced lung injury, and this might be one mechanism of inhibition of neutrophil and macrophage migration into the airspace by 14-MRMLs. This may be one mechanism of the anti-inflammatory and antifibrotic effects of 14-MRMLs. These findings suggest that prophylactic administration of 14-MRMLs may be clinically efficacious in preventing acute exacerbation of interstitial pneumonia and acute lung injury.  相似文献   
96.
Background:In recent years, the functional movement screen (FMS) and FMS training have attracted attention as a means of preventing injury, but no studies have examined the effect of such training in high-school baseball players. The aim of this study was to clarify the effect of FMS training on FMS score, physical function and baseball performance in high-school baseball players.Methods:Subjects in this randomized controlled clinical trial were high-school male baseball players assigned to either an FMS training group (intervention group) or a control group. The intervention group performed FMS training 4 times per week for 12 weeks. FMS ability, physical function, and baseball performance were measured prior to the intervention, 8, 12, and 24 weeks after the intervention in the subjects’ school environment.Results:A total of 71 baseball players aged 15 to 17 years were recruited and assigned to either an intervention group (n = 37) or control group (n = 34). There was no significant difference in the characteristics of participants between the 2 groups. Most FMS scores improved to 12 weeks after continued training. In the intervention group compared with the control group, deep squat, hurdle step, inline lunge, active straight leg raise, trunk stability push-up and rotary stability FMS score, total FMS score and eyes closed single leg stance time significantly increased after 8 weeks of training. While hurdle step, inline lunge, active straight leg raise, trunk stability push-up, total FMS score, and eyes closed single leg stance time significantly increased, pitching ball speed significantly decreased at the end of the 12 week training period. Eyes closed single leg stance time and feeling of fatigue significantly improved 12 weeks after training. The number of subjects who scored less than 14 for the total FMS score in the intervention group compared with control group were significantly less after 8 and 12 weeks of FMS training.Conclusion:FMS training for 8 weeks contributes to improving FMS scores for high-school baseball players, but FMS scores go down if FMS training is not continued.Trial registration:University Hospital Medical Information Network Center, Tokyo, Japan: UMIN000027553. Registered on May 30, 2017.  相似文献   
97.
Summary Conclusion. Near-infrared spectrometry is a new, rapid, and accurate method for measuring fecal fat that does not require a great deal of chemical knowledge and that can be used by anyone. This method is considered indispensable for the diagnosis of pancreatic steatorrhea and treatment follow-up. Methods. Fecal fats (GLC method, van de Kamer method), neutral sterols (GLC method), bile acids (GLC method) and short-chain fatty acids (HPLC method) were assayed by the respective conventional methods in 120 subjects, including patients with pancreatic dysfunction, and the results were compared with the those obtained by near-infrared spectrometry. The correlations between fecal fat excretion measured by the GLC method (x) and van de Kamer method (x) and by near-infrared spectrometry (y) were expressed by y=1.10 x-0.16 (r=0.949, P<0.01) and y=0.750x+1.654 (r=0.930, p<0.01), respectively. Results. The sensitivity and specificity of near-infrared spectrometry for fecal fats were 94.9 and 98.2%, respectively, when compared with the GLC method, and 87.5 and 90.0%, respectively, when compared with the van de Kamer method. In contrast, near-infrared spectrometry was not nearly as accurate as the conventional methods for determining neutral sterols, bile acids, and short-chain fatty acids.  相似文献   
98.
Isolated brain-retrocerebral neurohemal complex of the silkworm of Bombyx mori was stimulated electrically and the released bombyxin (an insulin-like neuropeptide) was measured using time-resolved fluoroimmunoassay. The amount of bombyxin release depended on the number of stimulus pulses delivered to the axonal tract of the bombyxin-producing (BP) neurosecretory cells, and 17 fg of bombyxin per pulse was released from a cell. The titer of bombyxin in the hemolymph of bombyxin-II injected pupae decreased exponentially, the half-life being 170 min. To relate firing activity of a population of BP cells to the hormone titer in the hemolymph, bombyxin titer and its change in the hemolymph were calculated numerically. We assumed that the amount of bombyxin release was proportional to the firing rate of BP cells and the released bombyxin was inactivated with the same time course of injected bombyxin. Our calculations suggested that the hemolymph bombyxin titer may fluctuate dynamically and the mean titer is 380 pg/ml, a level which is close to the actually determined bombyxin titer at middle stages of pupal-adult development.  相似文献   
99.
When BALB/cAJcl mice are intravenously injected with heat-killedPropionibacterium acnes (P. acnes) followed by an intravenous injection of lipopolysaccharide (LPS) 7 days later, massive necrosis is induced in the liver tissue and most of the mice die within 24 hours of LPS injection. Using this experimental model, acute hepatic failure was induced in various strains of mice and the difference in the response was studied. As a result, as in BALB/cAJcl mice, acut hepatic failure was also induced in BALB/ cAJcl-nu, AKR/J, C3H/HeNJcl, C57BL/6NJcl and DDy mice. However, as an exception, hepatic cell necrosis was hardly seen and the survival rate was remarkable high in C3H/HeJ mice, which genetically do not respond to LPS stimulation. These results indicate that for this experimental induction of acute hepatic failure, macrophages must be activated by the two-step stimulation ofP. acnes and LPS.  相似文献   
100.
Both radiation and stresses cause detrimental effects on humans. Besides possible health effects resulting directly from radiation exposure, the nuclear plant accident is a cause of social psychological stresses. A recent study showed that chronic restraint-induced stresses (CRIS) attenuated Trp53 functions and increased carcinogenesis susceptibility of Trp53-heterozygous mice to total-body X-irradiation (TBXI), having a big impact on the academic world and a sensational effect on the public, especially the residents living in radioactively contaminated areas. It is important to investigate the possible modification effects from CRIS on radiation-induced health consequences in Trp53 wild-type (Trp53wt) animals. Prior to a carcinogenesis study, effects of TBXI on the hematopoietic system under CRIS were investigated in terms of hematological abnormality in the peripheral blood and residual damage in the bone marrow erythrocytes using a mouse restraint model. Five-week-old male Trp53wt C57BL/6J mice were restrained 6 h per day for 28 consecutive days, and TBXI (4 Gy) was given on the 8th day. Results showed that CRIS alone induced a marked decrease in the red blood cell (RBC) and the white blood cell (WBC) count, while TBXI caused significantly lower counts of RBCs, WBCs and blood platelets, and a lower concentration of hemoglobin regardless of CRIS. CRIS alone did not show any significant effect on erythrocyte proliferation and on induction of micronucleated erythrocytes, whereas TBXI markedly inhibited erythrocyte proliferation and induced a significant increase in the incidences of micronucleated erythrocytes, regardless of CRIS. These findings suggest that CRIS does not have a significant impact on radiation-induced detrimental effects on the hematopoietic system in Trp53wt mice.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号