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   2238篇
  免费   134篇
  国内免费   22篇
耳鼻咽喉   78篇
儿科学   117篇
妇产科学   91篇
基础医学   153篇
口腔科学   93篇
临床医学   186篇
内科学   482篇
皮肤病学   58篇
神经病学   136篇
特种医学   103篇
外科学   524篇
综合类   33篇
预防医学   54篇
眼科学   98篇
药学   89篇
中国医学   7篇
肿瘤学   92篇
  2024年   2篇
  2023年   17篇
  2022年   17篇
  2021年   37篇
  2020年   35篇
  2019年   53篇
  2018年   56篇
  2017年   42篇
  2016年   96篇
  2015年   92篇
  2014年   130篇
  2013年   126篇
  2012年   160篇
  2011年   161篇
  2010年   97篇
  2009年   103篇
  2008年   214篇
  2007年   220篇
  2006年   176篇
  2005年   165篇
  2004年   122篇
  2003年   88篇
  2002年   56篇
  2001年   23篇
  2000年   29篇
  1999年   16篇
  1998年   5篇
  1997年   4篇
  1996年   1篇
  1995年   3篇
  1994年   1篇
  1992年   4篇
  1991年   7篇
  1990年   7篇
  1989年   6篇
  1988年   7篇
  1987年   3篇
  1986年   2篇
  1985年   1篇
  1984年   2篇
  1983年   1篇
  1979年   1篇
  1978年   2篇
  1973年   1篇
  1971年   1篇
  1968年   1篇
  1967年   1篇
排序方式: 共有2394条查询结果,搜索用时 106 毫秒
1.
2.
This study aimed to determine the effect of acute brucellosis on the auditory system. Forty-two patients with acute brucellosis were evaluated clinically, and with serological and audiological tests, before and after treatment. Hearing threshold averages were calculated at 11 different frequencies (250-8000 Hz) of the auditory airway, and statistical analysis was performed. The average hearing thresholds were > 20 dB, with standard audiometry at 6000-8000 Hz, and < 20 dB at all other frequencies. After treatment, the average auditory threshold decreased to < 20 dB at 6000-8000 Hz (p < 0.0001). Pure-tone hearing thresholds were improved at all frequencies after treatment, with statistically significant differences at all frequencies except 12,000, 14,000 and 16 000 Hz (p < 0.05). There was no permanent hearing loss caused by acute brucellosis, and hearing thresholds were restored after treatment. It was concluded that acute brucellosis affects the auditory system, especially at high frequencies, and that patients with all forms of brucellosis should be evaluated for hearing loss.  相似文献   
3.
It is well known that there might be an epidemiological association between Helicobacter pylori infection and extraintestinal diseases. This study aimed at determining H. pylori infection in epileptic patients. Forty-seven cryptogenic epileptic patients (Group 1) and 35 healthy people (Group 2) participated in this study. Presence of H. pylori infection was examined by H. pylori stool antigen (HpSA), H. pylori IgG, and IgM. HpSA was detected in 21 participants (44.6%) in Group 1 and in 3 participants (8.5%) in Group 2. H. pylori IgM was positive in 27 participants (57.4%) in Group 1 and in 8 participants (22.8%) in Group 2. H. pylori IgG was positive in 37 participants (78.7%) in Group 1 and in 13 participants (38%) in Group 2. The difference of rates of HpSA, H. pylori IgM and IgG in Groups 1 and 2 were found statistically significant (chi2=4.18, p=0.04; chi2=9.18, p=0.0017; chi2=14.58, p<0.001, respectively). We also compared presence of H. pylori infection between the epileptic patients with poor and good prognosis; HpSA positivity was detected in 15 (62.5%) of 24 and 6 (26%) of 23, respectively, and the differences were statistically significant (chi2=6.30, p=0.012). H. pylori IgM positivity was detected in 16 (66%) of 24 patients with poor prognosis and 11 (47.8%) of 23 patients with good prognosis (p>0.05). H. pylori IgG positivity was detected in 18 (75%) of 24 patients with poor prognosis and 19 (82.6%) of 23 patients with good prognosis. The differences of H. pylori IgM and IgG positivity rates in epileptic patients with poor and good prognosis were not found statistically significant (p>0.05). These results suggest a probable association between the acute H. pylori infection and epilepsy, especially with poor prognosis.  相似文献   
4.
Bone scintigraphy of the hands and wrists represents an important adjunct imaging technique that complements plain film radiographic examination in the evaluation of chronic wrist pain. In this study, the effectiveness of bone scintigraphy was investigated in the evaluation of chronic wrist pain in the patients without the history of trauma and any radiological and rheumatological abnormalities. Seventy-one patients with normal conventional radiographs and unexplained wrist pain were evaluated prospectively between 1998 and 2003 in our hand surgery clinic. There was no trauma history and no specific physical examination findings in the patients. The bone scintigraphy was done in all patients. Fifty-two of the all patients had normal scintigram. Seventeen of the remaining 19 patients showed increased activity over triquetrum (5 cases), lunatum (4 cases), trapezium (4 cases), hamatum (2 cases) and psiforme (2 cases). As the additional radiological investigations like MRI and CT revealed no bony abnormalities, the results of bone scintigraphy were evaluated as chronic ligamentous injuries. Two patients had diffuse increased uptake compatible with synovitis. The evaluation of bone scintigraphy correlated with clinical findings is effective to choose the most efficient treatment method in chronic wrist pain.  相似文献   
5.
We describe a case of neonatal osteofibrous dysplasia that was diagnosed 3 days after birth. Osteofibrous dysplasia is a fibro-osseous lesion rarely seen in long bones. It is also known as congenital osteitis fibrosa or ossifying fibroma of bones. Although it occurs in children under 10 years of age, it is extremely rare in newborn babies. It must be differentiated from adamantinoma due to their radiological appearance, predilection for tibia and fibula, clinical picture, and certain histological similarities.  相似文献   
6.
Purpose: To evaluate the relationship between glaucoma and Helicobacter pylori (H. pylori) infection. Participants: 137 patients with primary open angle glaucoma (POAG), 85 control subjects and 250 patients with gastric symptoms participated Methods: The presence of H. pylori infection in glaucoma patients, and glaucoma incidence in H. pylori infected patients  相似文献   
7.
Based on direct sequencing information from 5UTR and NS5B regions, we identified subtype 1b as a predominant hepatitis C virus genome in Turkey, which affected more than 91% of 79 patients studied. Next, the full genome sequence of a Turkish 1b isolate was obtained by the cloning of polypeptide-encoding region into 7 overlapping fragments. Turkish 1b isolate, which was named HCV-TR1, comprises 9361 nucleotides, including 306 nucleotides of 5UTR, a single long open reading frame of 9033 nucleotides, and 22 nucleotides of 3UTR. When compared to HCV 1b polypeptide sequences available at GenBank, the predicted polypeptide displayed a total of 36 amino acid substitutions, of which 16 was specific for HCV-TR1 isolate. Despite these changes, major structural and functional motifs of HCV proteins were maintained in HCV-TR1. In contrast, HCV-TR1 displayed amino acid substitutions in 6 out of 9 major cytotoxic T-cell epitopes. These data suggest that HCV-TR1 encodes functionally intact viral proteins, but it also encodes altered viral epitopes, which may affect host immune-response.  相似文献   
8.
OBJECTIVE: The purpose of this study was to investigate the effects of exogenous local Insulin like growth factor-I (IGF-I) on the repair of full-thickness articular cartilage defects in immature rabbits. DESIGN: Thirty-six skeletally immature New Zealand rabbits between 6 and 8 weeks old were used. A single defect, 3.5-mm-wide by 4-mm-deep full-thickness articular cartilage defect in the medial femoral condyle, was created. The defect was either filled with a collagen sponge or with a collagen sponge impregnated with 5 mug of recombinant IGF-I. The animals were sacrificed at 4, 8 or 12 weeks, and the repair tissue was examined macroscopically and histologically. Repair tissue was also examined immunohistochemically for the presence of type-I collagen, type-II collagen and PCNA at all weeks. RESULTS: Newly formed tissue in all of the defects in the IGF-I group had the gross, histological and histochemical appearance of a smooth, intact hyaline articular cartilage. The average total scores on the histological grading scale were significantly better (p<0.05) for the defects treated with recombinant IGF-I at all time points. Immunostaining with an antibody against type-II collagen showed the diffuse presence of the repair cartilage in the IGF-I treated defects. The control groups demonstrated minimum staining with type-II collagen antibody. CONCLUSIONS: These findings suggest that repair of full-thickness immature cartilage defects can be enhanced by recombinant IGF-I.  相似文献   
9.
Epitope instability can limit the applications of monoclonal antibody (mAb) technology in laboratory and clinical research. We exposed a group of representative antigens on human hepatocellular carcinoma (HCC) cells to physiochemical insults to study epitope stability as measured by mAb immunoreactivity. Each epitope was found to have a unique pattern of instability which serves to biophysically characterize the antigen and defines the conditions to which the antigen can be exposed during laboratory and clinical investigations. Individual antigens were found to be unstable within a surprisingly well defined window of solvent polarities while being stable on either side of that window. Several antigens were observed to be unstable when exposed to transient changes in pH. When a critical temperature between 42 degrees C and 65 degrees C was achieved, epitopes which were thermosensitive underwent a sudden loss in immunoreactivity. This critical temperature was found to be pH dependent. The effects of polarity, pH, and temperature on epitope stability are consistent with changes in protein structural conformation. In addition, we found that certain fixatives cause a time and concentration dependent loss of epitope immunoreactivity. This study provides a rapid and easy determination of monoclonal antibody-defined epitope stability; the results of which serve to guide further studies on the antigen and to characterize the antigen on the basis of its unique physiochemical stability.  相似文献   
10.
We have measured maternal serum levels of free alpha and beta subunits of human chorionic gonadotropin between 8 and 12 weeks of gestation in 704 women at increased risk for trisomy. This group was studied because of advanced maternal age or a previous birth with chromosomal abnormality. All sera had been collected prior to chorion villus biopsy for prenatal diagnosis. Serum levels of free alpha and beta hCG were determined by specific monoclonal antibody-based immunoradiometric assays. Analysis of chorionic tissue showed that in 38 of 704 (5.4%) pregnancies the fetus had a chromosome abnormality. There were 8 fetuses with trisomy 18 (1.1%) and 9 (1.3%) with trisomy 21. In all pregnancies carrying a trisomy 18 fetus, we observed either high levels of free alpha hCG or low levels of free beta hCG or both. More importantly, the calculated ratio of free beta hCG/alpha hCG was less than 0.25 multiples of the median (MoM) in 6 of 8 (75%) trisomy 18 cases. Only 21 of 666 mothers (3.2%) carrying a normal fetus had a ratio less than 0.25 MoM (P less than 0.0001). There was no difference between this ratio in trisomy 21 and normal pregnancy. Thus, when adjusted for gestational age, a low free beta hCG/alpha hCG ratio in maternal serum indicates a pregnancy at high risk [RR = 72 (95% CI 32, 162)] for trisomy 18.  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