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   1576篇
  免费   93篇
  国内免费   8篇
耳鼻咽喉   23篇
儿科学   26篇
妇产科学   24篇
基础医学   238篇
口腔科学   27篇
临床医学   96篇
内科学   393篇
皮肤病学   37篇
神经病学   119篇
特种医学   94篇
外科学   138篇
综合类   5篇
预防医学   43篇
眼科学   57篇
药学   134篇
中国医学   3篇
肿瘤学   220篇
  2024年   3篇
  2023年   12篇
  2022年   25篇
  2021年   38篇
  2020年   33篇
  2019年   33篇
  2018年   50篇
  2017年   47篇
  2016年   49篇
  2015年   55篇
  2014年   74篇
  2013年   68篇
  2012年   123篇
  2011年   129篇
  2010年   71篇
  2009年   60篇
  2008年   92篇
  2007年   111篇
  2006年   145篇
  2005年   91篇
  2004年   96篇
  2003年   84篇
  2002年   91篇
  2001年   9篇
  2000年   6篇
  1999年   12篇
  1998年   13篇
  1997年   8篇
  1996年   13篇
  1995年   6篇
  1994年   7篇
  1993年   5篇
  1992年   4篇
  1991年   4篇
  1989年   2篇
  1988年   4篇
  1986年   2篇
  1984年   2篇
排序方式: 共有1677条查询结果,搜索用时 15 毫秒
81.
We recently found that dietary raffinose suppressed allergic airway eosinophilia in ovalbumin-sensitized Brown Norway rats. Using this model in the present study, we compared the efficacy of other oligosaccharides with that of raffinose. Brown Norway rats were immunized s.c. with ovalbumin on d 0 and exposed to aerosolized ovalbumin on d 20; broncho-alveolar lavage fluid was obtained on d 21. In Expt. 1, rats were fed a control diet or diets supplemented with different oligosaccharides (50 g/kg diet, raffinose, alpha-linked galactooligosaccharide, fructooligosaccharide, and xylooligosaccharide). The number of eosinophils in the fluid was significantly lower in rats fed raffinose and alpha-linked galactooligosaccharide diets than in those fed the control diet. Dietary fructooligosaccharide and xylooligosaccharide did not affect airway eosinophilia. In Expt. 2, i.p. administration of raffinose and alpha-linked galactooligosaccharide, but not fructooligosaccharide and xylooligosaccharide, suppressed airway eosinophilia in rats fed the control diet. In Expt. 3, suppression of airway eosinophilia by dietary alpha-linked galactooligosaccharide occurred in cecectomized rats administered neomycin. Reduced levels of interleukin (IL)-4 and IL-5 mRNA in lung tissue were associated with the suppression of airway eosinophilia. We propose that indigestible oligosaccharides differ in their suppressive effect on allergic airway eosinophilia in ovalbumin-sensitized Brown Norway rats and that the effect appears not to be mediated by intestinal microflora.  相似文献   
82.
Purpose To investigate the differences between male and female rats and the effects of sex hormones on tissue changes in the lung and liver in a sepsis model.Methods Sixty Sprague-Dawley rats were divided into six groups of ten. Groups 1 and 2 were the control male and female groups, respectively, subjected only to sepsis; groups 3 and 4 were the male and female groups, respectively, subjected to sepsis, then given 0.04mg/kg estrogen + progesterone (E-P) intramuscularly (i.m.); and groups 5 and 6 were the male and female groups, respectively, subjected to sepsis, then given 0.5mg/kg testosterone (T) i.m. The rats were killed and the histopathological changes in the lung and liver were examined, and plasma endotoxin levels were measured.Results Histopathological examination revealed less congestion, portal inflammation, and focal necrosis of the liver, and less congestion, edema, and emphysematous and inflammatory changes in the lung in the E-P groups than in the other groups. Moreover, signs of systemic endotoxemia in plasma were proportionally less in the female rats and in the E-P groups than in the male rats and the T groups.Conclusion Female rats subjected to sepsis showed less liver and lung tissue damage and less systemic endotoxemia than male rats, because of the effects of female sex hormones.  相似文献   
83.
OBJECTIVES: Given that criteria for nasal surgery in individuals with obstructive sleep apnea syndrome (OSAS) have not been proposed, we investigated the effectiveness of nasal surgery for CPAP failure in patients with both severe OSAS and nasal obstruction. PATIENTS AND METHODS: Conventional nasal surgery was performed in 12 patients who were refractory to treatment by CPAP. The subject group consisted of 12 males (mean age, 54.2 +/- 9.2 years; range 39-66 years). The effect of nasal surgery was evaluated with data from preoperative and postoperative polysomunography. The nasal resistance value was first deduced to determine which OSAS patients with CPAP failure should undergo nasal surgery, compared to control values. RESULTS: Nasal surgery resulted in a significant decrease in nasal resistance, as measured by rhinomanometry, from 0.57 +/- 0.31 Pa/cm3 /sec to 0.16 +/- 0.03 Pa/cm3/sec and rendered all patients tolerant to CPAP. In addition, the lowest nocturnal oxygen saturation significantly increased from 68.3 +/- 12.1% to 75.3 +/- 7.1% after surgery. Subjectively, Epworth sleepiness scale (ESS) significantly decreased from 11.7 +/- 4.1 to 3.3 +/- 1.3 after surgery, but the number of apnea and hypopnea episodes per hour did not change significantly. In five patients, for whom it was possible to perform a CPAP titration before nasal surgery, the value decreased significantly from 16.8 +/- 1.1 to 12.0 +/- 1.9 cmH2O. The bilateral nasal resistance of the 410SAS patients with CPAP therapy (control group) was 0.24 +/- 0.11 Pa/cm3/sec. The cut off value for differentiation between CPAP failure patients and control group was determined as 0.38 Pa/cm3 /sec. CONCLUSION: Increased nasal resistance is a determinant of CPAP failure, and the surgical correction of severe nasal obstruction should thus be considered to facilitate treatment of OSAS patients with CPAP.  相似文献   
84.
The latest heavy ion therapy tends to require information about the spatial distribution of the quality of radiation in a patient's body in order to make the best use of any potential advantage of swift heavy ions for the therapeutic treatment of a tumour. The deflection of incident particles is described well by Molière's multiple-scattering theory of primary particles; however, the deflection of projectile fragments is not yet thoroughly understood. This paper reports on our investigation of the spatial distribution of fragments produced from a therapeutic carbon beam through nuclear reactions in thick water. A DeltaE-E counter telescope system, composed of a plastic scintillator, a gas-flow proportional counter and a BGO scintillator, was rotated around a water target in order to measure the spatial distribution of the radiation quality. The results revealed that the observed deflection of fragment particles exceeded the multiple scattering effect estimated by Molière's theory. However, the difference can be sufficiently accounted for by considering one term involved in the multiple-scattering formula; this term corresponds to a lateral 'kick' at the point of production of the fragment. This kick is successfully explained as a transfer of the intra-nucleus Fermi momentum of a projectile to the fragment; the extent of the kick obeys the expectation derived from the Goldhaber model.  相似文献   
85.
The early detection of depression and suicidal ideation is essential for the prevention of suicide in the community. This study therefore aimed to develop a brief screen for depression and suicidal ideation that can be easily administered in primary-care settings. The Self-rating Depression Scale (SDS), the Hospital Anxiety and Depression Scale (HADS) and a modified version of the Composite International Diagnostic Interview (CIDI) were administered by 353 residents of a single community aged 64 years and over. A five-item screen was derived from SDS and HADS, using CIDI as the external criterion (study 1). The scale was modified so that it was more appropriate for our use, and was labeled the Depression and Suicide Screen (DSS). Its validity and reliability were examined among a further 382 residents of the same community aged 64 years and over, using the Short-Form Geriatric Depression Scale (GDS-S) as the external criterion (study 2). The DSS was internally consistent (Cronbach's alpha=0.62). Its reliability in detecting depression (defined as >or= 6 in GDS-S) and suicidal ideation (screened out by the inquiry by our trained staff) was 0.768 and 0.721, respectively. For depression, the sensitivity was 0.705; specificity, 0.729; positive predictive value (PPV), 0.446; negative predictive value (NPV), 0.888; and the overall diagnostic power, 0.723. For suicidal ideation, its sensitivity was 0.698; specificity, 0.693; PPV, 0.317; NPV, 0.926; and overall diagnostic power, 0.694. The DSS demonstrated a reasonable level of sensitivity and specificity in identifying both depression and suicidal ideation among the elderly within a community.  相似文献   
86.
Tubulin beta II (Tub-II) is widely distributed in the developing neuronal axons and dendrites. Recent studies have demonstrated that Tub-II is also important in the early development of the human brain, and Tub-II represents a marker for progenitor and neural stem cells. To elucidate the correlation between the developing brain and neuroepithelial tumors (NETs), the present study assessed Tub-II expression by NETs and normal brain tissue using immunohistochemical and immunoblot analyses. In the gliomas, decreased numbers and staining intensities of Tub-II-positive cells tended to be associated with increased differentiation. Conversely, neuronal neoplasms displayed high percentages and strong staining intensities among the Tub-II-positive cells, irrespective of differentiation. In neuronal neoplasms and neoplasms with neuronal differentiation, Tub-II staining was far more intense and more homogeneous than Tub-II staining in gliomas. These results indicate that the expression of Tub-II in NETs may reflect architectural changes in the developing brain and may support the hypothesis that neuroepithelial tumors originate from glioneuronal progenitor cells capable of generating astrocytic, and neuronal cell types.  相似文献   
87.
We report the use of topical application of recombinant human basic fibroblast growth factor (rhbFGF) to successfully treat therapy-resistant, chronic leg ulcers in scleroderma. Endothelial cell FGF receptors are directly stimulated by bFGF; also, bFGF promotes the regeneration of capillary-rich granulation tissue. We conclude that topical bFGF may be a powerful new pharmacologic tool for treating severe skin ulcers.  相似文献   
88.
89.
We examined the correlations of hemoglobin A(1c) (HbA(1c)) with each plasma glucose (PG) level obtained at 0 (the same day), 1 and 2 month(s) prior to HbA(1c) determination. Data were from glycemic profiles of four patients of type 2 diabetes mellitus treated with tablets whose HbA(1c) and pre- and post-breakfast PG levels were monitored each month. There was no significant difference in the correlation coefficients in cases 1 and 2, who presented with linear glycemic time courses. In contrast, HbA(1c) correlated with 1-month-earlier pre-breakfast PG level more strongly than 2-month-earlier post-breakfast PG level in cases 3 and 4, and than same-day post-breakfast PG level in case 3 (P<0.05, ANOVA). The cases 3 and 4 presented with fluctuating glycemic time courses. Samples were separated into upslope's and downslope's sections according to HbA(1c) fluctuation in the latter two cases. Reflecting around the 1-month lag between HbA(1c) and PG, the two sections' regression lines for PG versus HbA(1c) corresponded in the only samples related to 1-month-earlier pre- and post-breakfast PG (t-test). In conclusion, it appears that pre- and post-breakfast PG levels are the most reliable predictors of 1-month-later HbA(1c) in type 2 diabetic outpatients who undergo medical examinations every month.  相似文献   
90.
Purpose To investigate whether sympathetic nerve injury occurs during aortic surgery and how reinnervation takes place afterward.Methods Imaging with 123I-metaiodobenzylguanidine (MIBG) was performed in 12 patients (aortic group) who underwent aortic surgery (ascending replacement 3, ascending-arch replacement 9) before and 3 weeks after surgery. In 8 of 12 patients, MIBG scintigraphy was performed 1 and 2 years after surgery. Twelve patients (control group) who underwent open-heart surgery (mitral valve repair: 11; tricuspid valve replacement: 1) were studied using MIBG scintigraphy. The heart-to-mediastinum (H/M) activity ratio was obtained from planar images. The myocardial single-photon-emission computed tomography image was divided into five segments and the regional tracer uptake was scored from 0 = absent to 3 = normal uptake.Results No significant difference in the H/M ratio in either early and delayed planar scans was observed between both groups before surgery. The H/M ratios significantly decreased 3 weeks after surgery in the aortic group, whereas there was no significant change in the control group. The H/M ratio did not recover to the preoperative level within 2 years. In these 8 patients, the regional uptake of MIBG improved in the anterior and septal regions 1 year after surgery.Conclusion During ascending or ascending-arch replacement, the sympathetic nerve was globally denervated and slight reinnervation was observed within 2 years. The anterior and septal regions showed a rapid reinnervation, whereas other regions did not.  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