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   1222篇
  免费   70篇
  国内免费   3篇
耳鼻咽喉   26篇
儿科学   55篇
妇产科学   14篇
基础医学   146篇
口腔科学   25篇
临床医学   105篇
内科学   311篇
皮肤病学   20篇
神经病学   123篇
特种医学   105篇
外科学   87篇
综合类   4篇
预防医学   53篇
眼科学   18篇
药学   89篇
中国医学   3篇
肿瘤学   111篇
  2022年   13篇
  2021年   13篇
  2020年   15篇
  2019年   15篇
  2018年   17篇
  2017年   19篇
  2016年   18篇
  2015年   26篇
  2014年   39篇
  2013年   52篇
  2012年   66篇
  2011年   72篇
  2010年   55篇
  2009年   38篇
  2008年   61篇
  2007年   78篇
  2006年   59篇
  2005年   60篇
  2004年   82篇
  2003年   86篇
  2002年   73篇
  2001年   13篇
  2000年   15篇
  1999年   14篇
  1998年   19篇
  1997年   21篇
  1996年   20篇
  1995年   12篇
  1994年   20篇
  1993年   13篇
  1992年   9篇
  1991年   11篇
  1990年   14篇
  1989年   7篇
  1988年   17篇
  1986年   5篇
  1985年   10篇
  1984年   9篇
  1982年   7篇
  1981年   6篇
  1979年   6篇
  1975年   7篇
  1972年   7篇
  1971年   7篇
  1970年   5篇
  1969年   6篇
  1968年   6篇
  1967年   5篇
  1966年   8篇
  1956年   5篇
排序方式: 共有1295条查询结果,搜索用时 31 毫秒
91.
We describe the sonographic findings in a case of Lennert's lymphoma, a rare type of peripheral T-cell lymphoma, involving the subcutaneous tissues of the arm. The sonographic appearance was thought to be more helpful than MRI to establish the diagnosis.  相似文献   
92.
Canola oil (Can), as well as some other oils, shortens the survival of SHRSP rats compared with soybean oil (Soy). Although detrimental factors other than phytosterols have not been identified, they are likely to be hydrophobic and transmissible to pups. To test this possibility, female SHRSP rats (F0) were fed a diet supplemented with Can or Soy and mated at 11 wk of age. The growth of suckling pups (F1) from the Can-fed dams was significantly retarded compared with that of pups from the Soy-fed dams. Half of the male pups (F1) were weaned to the same diet as their dams (Can-->Can and Soy-->Soy groups) and the rest were weaned to the other diet (Can-->Soy and Soy-->Can groups). The survival rate of the male pups (F1) was significantly lower in the Can-->Can group than in the Soy-->Can group, and in the Can-->Soy group than in the Soy-->Soy group, indicating that the oils fed to dams differently affected the growth and survival of pups. There were fewer pups per dam in the Can-fed dams (F0) than in the Soy-fed dams, and in the dams (F1) of the Can-->Can and Soy-->Can groups than in those of the Can-->Soy and Soy-->Soy groups. Although Can is nutritionally detrimental to SHRSP rats compared with Soy, no direct evidence has been obtained thus far relating these observations to human nutrition.  相似文献   
93.
A series of novel 26-substituted milbemycin A4 derivatives was synthesized from 5-O-t-butyldimethylsilyl-26-hydroxymilbemycin A4 prepared by selenium dioxide oxidation of 5-O-t-butyldimethylsilyl-milbemycin A4. Their acaricidal activities were assessed against the organophosphorus-sensitive two-spotted spider mite (Tetranychus urticae) on the primary leaves of cowpea plants (Vigna sinesis Savi species) by spraying.  相似文献   
94.
PURPOSE: Very fast activity was investigated on the ictal EEGs of epileptic spasms to elucidate the pathophysiology of West syndrome (WS) and related disorders from a novel point of view. METHODS: The traces of scalp ictal EEG of spasms temporally were expanded in 11 patients whose clinical diagnosis was symptomatic WS in six, cryptogenic WS in two, Aicardi syndrome in one, and symptomatic generalized epilepsy after WS in the remaining two. Time evolution of averaged power spectra of the ictal fast activity also was analyzed in each patient. RESULTS: Rhythmic gamma activity with frequency ranging from 50 to 100 Hz was detected in a total of 345 of 537 spasms. Fast activity was seen bilaterally in nine patients, was lateralized to one hemisphere in another, and appeared independently on each hemisphere in the remaining infant with Aicardi syndrome. Power spectra showed a clear peak corresponding to spasm-associated gamma rhythm, with frequency centering approximately 65 Hz and ranging from 51 to 98 Hz. The morphology and spectral characteristics of ictal gamma rhythm were completely different from those of muscle activity or alternating current (AC) artifacts. CONCLUSIONS: Spasm-associated gamma activity was clearly detected on the scalp. This observation may provide a clue to the pathophysiology of spasms.  相似文献   
95.
1. Serum hepatocyte growth factor (HGF) is considered to be a potent marker of vascular endothelial injury. The present study was designed to examine serum HGF levels in atrial fibrillation and after successful direct current (DC) cardioversion. 2. We measured serum HGF levels before and 7 days and 1 month after DC cardioversion in 39 patients with atrial fibrillation in whom sinus rhythm was maintained for at least 7 days after DC cardioversion and in 30 age- and sex-matched normal control subjects with sinus rhythm. We also measured acetylcholine-induced changes in forearm blood flow (FBF) using venous occlusive plethysmography in 10 patients. 3. Serum HGF levels were significantly higher in the atrial fibrillation patients (both lone atrial fibrillation and with underlying heart disease) than in the controls (0.16 +/- 0.07 vs 0.10 +/- 0.04 ng/mL; P < 0.001). Seven days after successful DC cardioversion, the patients' serum HGF levels had decreased significantly (0.16 +/- 0.07 vs 0.12 +/- 0.06 ng/mL; P < 0.05) and in the 24 patients maintaining sinus rhythm 1 month after DC cardioversion, serum HGF levels decreased to control values (0.10 +/- 0.08 ng/mL at 1 month). Serum HGF levels of the 15 patients who had relapsed into atrial fibrillation 1 month after DC cardioversion tended to decrease 7 days after DC cardioversion, but increased again 1 month after DC cardioversion. Percentage changes in FBF between baseline and the highest dose of acetylcholine before and after DC cardioversion were 180 +/- 98 and 323 +/- 196%, respectively (P = 0.0051). The rate of increase in FBF at the highest dose of acetylcholine between before and after DC cardioversion correlated negatively with the rate of decrease in serum HGF levels between before and after DC cardioversion (r = -0.837; P = 0.0025). 4. This study is the first to demonstrate that serum HGF levels increase in atrial fibrillation and decrease after successful DC cardioversion. This may reflect the fact that atrial fibrillation induces vascular endothelial injury.  相似文献   
96.
We examined the RDH5 gene for mutations in two unrelated Japanese families with fundus albipunctatus. Each proband with fundus albipunctatus in two families (family A's case was atypical with sectorial retinitis pigmentosa, while family B's case was typical), and 2 obligate carriers underwent molecular analysis of their RDH5 gene. DNA was amplified for all coding exons of the RDH5 gene with established primer pairs, and sequenced directly. Each family had a different mutation in the RDH5 gene. Family A had a homozygous mutation (Gly107Arg) while family B had a compound heterozygous mutation (Arg280His and Leu310GluVal). The obligate carriers were heterozygous with the wild-type and mutant-type alleles. The homozygous Gly107Arg mutation in the RDH5 gene described in this paper has not previously been described, though compound heterozygous mutations (Gly107Arg and Leu310GluVal) in the RDH5 gene have previously been reported.  相似文献   
97.
Hypocholesterolemic activity of dietary polyunsaturated fatty acids is observed after relatively short-term but not long-term feedings, and their long-term feedings are suspected to accelerate aging through tissue accumulation of lipid peroxides and age pigments (lipofuscin). To define the long-term effects of fats and oils in more detail, female mice were fed a conventional basal diet supplemented with lard (Lar), high-linoleic (n-6) safflower oil (Saf), rapeseed oil (Rap), high-alpha-linolenic (n-3) perilla oil (Per), or a mixture of ethyl docosahexaenoate and soybean oil (DHA/Soy) from 17 weeks to 71 weeks of age. The DHA/Soy and Per groups had decreased serum cholesterol levels compared with the Lar and Saf groups, but the difference between the Lar and Saf groups was not significant. The 3-hydroxy-3-methyglutary-CoA (HMG-CoA) reductase activity in the liver was also significantly lower in the Per and DHA/Soy groups. However, no significant difference in lipofuscin contents in the brain and liver was observed among the 5 dietary groups, despite significant differences in peroxidizability indices of the dietary and/or tissue lipids. These results indicate that n-3 fatty acid-rich oils are hypocholesterolemic by suppressing hepatic HMG-CoA reductase activity compared with animal fats and high-linoleic (n-6) oil, but tissue lipofuscin contents are not affected by a long-term feeding of fats and oils with different degree of unsaturation in mice.  相似文献   
98.
PURPOSE: The objectives of this study were to examine the degree of psychological distress during the first 6 months after diagnosis of gastric cancer and investigate the relation to psychological support from public health nurses and family members. METHODS: One hundred and five patients with stomach, colorectal, or esophagus cancer were mailed a questionnaire. They were asked questions concerning the level of shock on the day of diagnosis, at 1-week after the diagnosis, and at 6 months post diagnosis. In addition, their physical and psychological status was assessed at the 6-month time point. They were also asked about perceived psychological support from public health nurses and family members. The relation between psychological distress and such psychological support was then assessed using multiple regression analyses. RESULTS: The levels of shock on the day of diagnosis and after 1-week were both significantly related to the psychological support from public health nurses. Physical and psychological status at 6 months post diagnosis was significantly related to the level of psychological support from the patient's family members. CONCLUSION: The study revealed that psychological support from public health nurses improves the level of patient psychological distress during the first 1 week after the cancer diagnosis. Psychological support from family members facilitates the physical and psychological adjustment at 6 months post diagnosis. The results indicate that psychological support is important just after cancer diagnosis and for longer term adjustment, pointing to a major role of health care professionals alleviating problems associated with cancer diagnosis.  相似文献   
99.
100.
OBJECTIVE: Image interpretation in positron emission tomography (PET) using F-18-fluoro-2-deoxy-D-glucose (FDG) is usually performed for images obtained at 1 h postinjection (PI) of FDG, but it remains unknown whether this is the optimal time for imaging patients with pancreatic disease. The aim of this study was to assess the optimal scan time for FDG-PET for patients suspected of having pancreatic cancer. PATIENTS AND METHODS: Forty-four patients with suspected pancreatic cancer underwent FDG-PET scans at both 1 h and 2 h PI. Tracer uptake in the pancreatic lesions and possible liver metastasis was interpreted qualitatively, using a 5-point grading system (0 = normal, 1 = probably normal, 2 = equivocal, 3 = probably abnormal, and 4 = definitely abnormal) by 4 nuclear medicine physicians independently, who were blind to all clinical information. Detection performance with each image was compared using receiver operating characteristic (ROC) analysis. An average score of the 4 readers for each patient was also defined as consensus average index (CAI) and compared between the two images. RESULTS: ROC results indicated no significant differences in detection performance (Averaged areas under ROC curves of 1 h vs. 2 h were 0.92 vs. 0.90 for primary tumor, and 0.81 vs. 0.85 for liver metastases). There were no significant differences in CAIs between 1 h and 2 h PI images in interpreting primary tumor and positive liver metastases, but a significant difference was observed for cases without liver metastases (p < 0.05). CONCLUSIONS: The certainty of excluding liver metastases was increased when the 2h image was used, although ROC analysis did not establish a difference between 1 h and 2 h imaging for differentiating malignant and benign lesions in primary pancreatic cancer or its liver metastases.  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