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   11519篇
  免费   1052篇
  国内免费   564篇
耳鼻咽喉   1449篇
儿科学   276篇
妇产科学   69篇
基础医学   1753篇
口腔科学   1051篇
临床医学   1007篇
内科学   1674篇
皮肤病学   167篇
神经病学   121篇
特种医学   250篇
外国民族医学   1篇
外科学   1029篇
综合类   1884篇
预防医学   365篇
眼科学   179篇
药学   1110篇
  7篇
中国医学   395篇
肿瘤学   348篇
  2024年   21篇
  2023年   163篇
  2022年   272篇
  2021年   399篇
  2020年   376篇
  2019年   380篇
  2018年   342篇
  2017年   329篇
  2016年   410篇
  2015年   382篇
  2014年   685篇
  2013年   823篇
  2012年   624篇
  2011年   676篇
  2010年   550篇
  2009年   532篇
  2008年   512篇
  2007年   547篇
  2006年   527篇
  2005年   468篇
  2004年   407篇
  2003年   365篇
  2002年   374篇
  2001年   319篇
  2000年   286篇
  1999年   281篇
  1998年   266篇
  1997年   245篇
  1996年   202篇
  1995年   152篇
  1994年   181篇
  1993年   156篇
  1992年   111篇
  1991年   96篇
  1990年   95篇
  1989年   89篇
  1988年   76篇
  1987年   50篇
  1986年   42篇
  1985年   42篇
  1984年   60篇
  1983年   27篇
  1982年   32篇
  1981年   22篇
  1980年   33篇
  1979年   24篇
  1978年   15篇
  1977年   13篇
  1976年   19篇
  1974年   14篇
排序方式: 共有10000条查询结果,搜索用时 49 毫秒
91.
BACKGROUND: In vitro studies have shown much higher H1-receptor antagonist potency with desloratadine (DL) compared to fexofenadine (FEX), although it is unclear whether this has any clinical relevance on disease control parameters in seasonal allergic rhinitis (SAR), especially for nasal congestion. OBJECTIVE: To compare the relative efficacy between presently recommended doses of DL and FEX on daily measurements of peak nasal inspiratory flow (PNIF) and nasal symptoms in SAR. METHODS: Forty-nine patients with SAR were randomized into a double-blind, placebo-controlled cross-over study during the grass pollen season, comparing 2 weeks of once daily treatment with (a) 180 mg FEX or (b) 5 mg DL, taken in the morning. There was a 7-10 day placebo run-in and washout prior to each randomized treatment. Measurements were made in the morning (AM) and in the evening (PM) for PNIF (the primary outcome variable), nasal and eye symptoms. The average of AM/PM values were used for analysis. RESULTS: There were significant (P < 0.05) improvements, compared to placebo, with FEX and DL, for PNIF, nasal blockage, nasal irritation, and total nasal symptoms, but not nasal discharge or eye symptoms. There were no significant differences between active treatments. Values for PNIF (L/min) for mean placebo baseline, mean difference from baseline (95% CI for difference) were 126, 10 (4-16) for FEX; and 122, 11 (4-17) for DL. The mean difference (95% CI) between FEX vs. DL was 1 L/min (-7-8). Values for total nasal symptoms (out of 12) were: 3.2, 0.7 (0.2-1.2) for FEX; and 3.4, 0.9 (0.3-1.5) for DL, and for nasal blockage (out of 3) were: 1.1, 0.2 (0.1-0.4) for FEX; and 1.2, 0.3 (0.1-0.5) for DL. The mean difference (95% CI) in total nasal symptoms and nasal blockage between FEX vs. DL was 0.1 (-0.6-0.8) and 0.1 (-0.2-0.3), respectively. CONCLUSIONS: Recommended once daily doses of fexofenadine and desloratadine were equally effective in improving nasal peak flow and nasal symptoms in SAR.  相似文献   
92.
应用人自体血清培养人口腔黏膜上皮的实验研究   总被引:1,自引:0,他引:1  
目的 研究人自体血清培养人口腔黏膜移植生长的生物学特性,为组织工程化尿道提供新材料。方法 将人自体血清培养黏膜移植于裸鼠体内,分别于移植后2、3、4、6周观察培养黏膜生长与转归,应用anti—HLA免疫荧光鉴定成活黏膜组织属性,应用抗人Ⅳ型胶原及抗人层黏蛋白为基底膜形成指标。结果 裸鼠体内移植培养黏膜成活生长分化良好,anti—HLA免疫荧光证实为移植的培养人黏膜组织;免疫组化发现移植后3周开始形成基底膜,4周形成完整的基底膜。结论 自体血清培养的人口腔黏膜可形成功能完整的上皮组织。  相似文献   
93.
The aim of this study was to investigate the reactivity of the nasal mucosa of patients with pollen allergy compared to healthy controls, when challenged with histamine outside the pollen season. Assessments were made with symptom score, acoustic rhinometry, nasal peak expiratory and inspiratory flow (NPEF and NPIF) and rhinomanometry in order to find the most sensitive method for the purpose. Twenty-one patients with seasonal allergic rhinitis and 20 healthy controls were challenged with histamine dihydrochloride in increasing concentrations (0.01, 0.1, 1.0 mg/ml) locally in the nose. Our results show no difference in mucosal reactivity between the patients and controls regardless of the method used. When comparing the methods we find that NPIF and NPEF are more sensitive to mucosal changes than the other methods we have studied.  相似文献   
94.
When nasotracheal intubation with a fiberoptic bronchoscope is performed, the tube may be blocked in the nasal cavity or larynx, resulting in several complications including epistaxis and hoarseness. We review the causes and complications of tube blockage and discuss optimal techniques for minimizing it.  相似文献   
95.
为探讨胆汁返流性胃炎的发病机理和应用中药治疗此病的效果,作者进行了胃粘膜超微结构观察。在治疗前、后取胃粘膜做光、电镜检查,发现本病胃粘膜变化突出的特点是淋巴细胞侵入腺细胞内,溶解腺细胞,破坏细胞间联接装置,使腺腔破溃,腺管萎缩。以上变化可占全部病例的87.5%。另一特点是腺细胞内出现微囊(8例中有4例),这在慢性胃炎尚未见有电镜观察报道。作者认为胆汁返流性胃炎可以是慢性萎缩性胃炎的前驱,而腺体萎缩的原因是由于淋巴细胞的浸润破坏;这为由细胞介导引起的胃腺细胞损伤提供了形态学依据。  相似文献   
96.
A chromium electroplating worker, suffering from epistaxis during work, was found to have nasal septum perforation. To determine the etiology and prevalence of nasal septum lesions, we conducted a survey of seven chromium electroplating factories and examined 79 workers. Forty workers from three aluminum electroplating factories were also enrolled as the reference group. Subjects were thoroughly examined by an otolaryngologist and each of them provided a blood and urine sample. A questionnaire interview regarding symptoms of the upper respiratory tract, past medical history, life style, and work history was also conducted. Air chromium concentrations were measured by taking area samples for 4–6 hours. Based on field observation and chromium measurements, we divided chromium electroplating into three different exposure zones: workers directly dealing with electroplating tanks (n = 31), other process workers (n = 29), and office workers and drivers (n = 19). Among the 79 chromium electroplating workers, there were 16 cases of nasal septum perforation, and 42 with either scar formation or ulceration; 10 chromium electroplating workers developed skin ulcers after performing chrome plating. No workers from aluminum electroplating factories had any nasal septum or skin abnormalities. There was a consistent trend between the degree of chromium exposure and the signs and symptoms related to the nose, throat, and skin. Immediate improvement of occupational hygiene is warranted.  相似文献   
97.
肠易激综合征患者结肠粘膜扫描电镜观察   总被引:2,自引:0,他引:2  
应用扫描电镜观察10例肠易激综合征(IBS)患者降结肠粘膜的超微结构并和2例正常者进行比较性研究,结果发现IBS组结肠粘膜上皮细胞表面微绒毛有局灶性破坏,破坏区微绒毛排列不整齐,数量稀少或缺如,结肠腺数量明显增多,腺窝开口大。腺窝处见有大量粘液分泌物和数量显著增多的杯状细胞。作者认为,IBS并非是消化迫功能性疾病,而是有结肠粘膜超微结构改变的器质性疾病  相似文献   
98.
BACKGROUND: Chronic mucocutaneous candidiasis (CMC) is a rare disorder characterized by persistent or recurrent candidal infections of the skin, nails and mucous membranes or by a variable combination of endocrine failure as well as immunodeficiency. Oral clinicopathological features of CMC have seldom been described in detail. METHODS: Seven patients with CMC were reported in the study. The clinical and histological findings, etiological Candida species, immunological evaluation, and therapeutic pattern of oral lesions, were analyzed. RESULTS: Long-standing whitish hyperplastic and nodule-like lesions with exaggerated deep fissure were the typical and characteristic oral manifestations presented by all patients. The tongue was the most common site affected. Histologically, no obvious distinction was found between CMC and other forms of candidal infection. Abnormal proportions of T-lymphocyte subsets and positive titers of autoantibody were observed in three subjects (42.9%) and one patient (14.3%) respectively. Meanwhile, four subjects (57.1%) showed decreased albumin and increased globulin, three cases (42.9%) had high levels of ESR. But no iron deficiency was found. Candida albicans was the microorganism isolated from these patients. CONCLUSIONS: Multiple and widespread candidal infectious lesions can be observed on the oral cavity of CMC patients. Hyperplastic and nodule-like lesion with irremovable whitish patches and deep fissure are the most common oral manifestations of these patients. Dentists, otolaryngologists and pediatricians should be familiar with the clinical appearances of CMC to make an accurate diagnosis. Potential systemic disorders should be concerned to avoid the reoccurrence of oral candidiasis.  相似文献   
99.
In an attempt to establish an in vitro/in situ correlation of intestinal permeability data, the permeability coefficients (P app) for a series of model peptides, which were determined using an in situ perfused rat ileum model, were compared to the permeability coefficients (P mono) determined using an in vitro cell culture model (Caco-2). The model peptides, which were all blocked on the N-terminal (acetyl, Ac) and the C-terminal (amide, NH2) ends, consisted of D-phenylalanine (F) residues (e.g., AcFNH2, AcFFNH2, AcFFFNH2). To alter the degree of hydrogen bonding potential, the nitrogens of the amide bonds were sequentially methylated [e.g., AcFF(Me)FNH2, AcF(Me)F(Me)FNH2, Ac(Me)F(Me)F(Me)FNH2, Ac-(Me)F(Me)F(Me)FNH(Me)]. These peptides were shown not to be metabolized in the in situ perfused rat ileum system. The results of the transport experiments showed that there were poor correlations between the apparent permeability coefficients (P app) determined in an in situ perfused rat ileum model and the octanol–water partition coefficients (r = 0.60) or the hydrogen bonding numbers (r = 0.63) of these peptides. However, good correlations were observed between the in situ P app values for these peptides and their partition coefficients in heptane–ethylene glycol (r = 0.96) and the differences in their partition coefficients between octanol–water and isooctane–water (r = 0.86). These results suggest that lipophilicity may not be the major factor in determining the intestinal permeability of these peptides and that hydrogen bonding potential may be a major contributing factor. A good correlation (r = 0.94) was also observed between the P app values determined for these peptides in the in situ perfused ileum model and those P mono values determined in the in vitro cell culture model (Caco-2) (Conradi et al., Pharm. Res. 8:1453–1460, 1991). These results suggest that the permeability values determined in the Caco-2 cell culture model may be a good predictor of the intestinal permeability of peptides.  相似文献   
100.
目的观察耳廓复合游离组织瓣连续法修复鼻翼缺损的疗效,以探讨鼻翼缺损的有效修复手段。方法耳廓复合游离组织瓣2次连续法修复鼻翼缺损7例,移植物面积0.5cm×0.7cm~0.8cm×1.2cm。结果7例耳廓复合游离组织瓣移植后全部成活。术后随访6~18个月,移植物无明显回缩,鼻外形满意。结论耳廓复合游离组织瓣连续移植修复鼻翼缺损,适合较严重鼻翼缺损,手术成功率高,术后鼻外形满意,双侧分次取材,耳廓外形双侧对称无畸形。  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