首页 | 官方网站   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   1066篇
  免费   49篇
  国内免费   3篇
医药卫生   1118篇
  2023年   10篇
  2022年   55篇
  2021年   52篇
  2020年   38篇
  2019年   37篇
  2018年   48篇
  2017年   20篇
  2016年   34篇
  2015年   28篇
  2014年   46篇
  2013年   74篇
  2012年   84篇
  2011年   65篇
  2010年   56篇
  2009年   45篇
  2008年   46篇
  2007年   59篇
  2006年   45篇
  2005年   64篇
  2004年   45篇
  2003年   44篇
  2002年   51篇
  2001年   6篇
  2000年   8篇
  1999年   10篇
  1998年   8篇
  1997年   1篇
  1996年   3篇
  1995年   2篇
  1994年   6篇
  1993年   7篇
  1992年   3篇
  1991年   3篇
  1990年   4篇
  1989年   2篇
  1987年   3篇
  1986年   1篇
  1983年   3篇
  1982年   2篇
排序方式: 共有1118条查询结果,搜索用时 15 毫秒
1.
Perianal mucinous adenocarcinoma is a rare tumour which may be associated with long‐standing chronic perianal sepsis. Early diagnosis is challenging and is based on a high index of clinical suspicion and specific histological features. Definitive treatment is surgical, in the form of an abdomino‐perineal resection. We hereby describe a case of a perianal mucinous adenocarcinoma arising from long‐standing recurrent perianal fistula and complement this with a brief review of the literature pertaining in particular to the management of this condition.  相似文献   
2.
Purpose  Congenital clasped thumb is a deformity that is associated with heterogeneous congenital anomalies and it has been addressed in many congenital syndromes. The aim of this study was to diagnose and evaluate cases of clasped thumb as regards the associated congenital anomalies and syndromes, and evaluation of the results of treatment of such cases. Methods  A prospective study on 40 patients with 73 clasped thumbs was done. All the patients’ data regarding their personal, family, pregnancy and developmental histories were recorded. All the patients were exposed to thorough clinical and radiological examination and genetic assessment. The cases were classified using the Tsuyuguchi et al. (J Hand Surg [Am] 10:613–618, 1985) classification into three types. Conservative treatment was adopted in ten hands, and surgical treatment was performed for 28 hands in 17 patients, with an average follow-up of 26 months. Results  Positive consanguinity was recorded in 57.5% of cases. Associated anomalies were recorded in 77.5% of cases. Type I was the most common one, followed by type III and then type II. Conservative treatment is effective in type I cases when presented early, and all patients were satisfied with the results of surgical treatment. Conclusions  We reported associated anomalies which are to our knowledge have not mentioned before in the literature which include; congenital blindness, radial deviation of the index finger and ventricular septal defect. We found that 68% of the patients had associated syndromes, and this has not been mentioned before. In this study, we found that there were no difference between type II and type III clasped thumb as regards the pathological findings, severity, the operative procedures, the treatment protocol and the operative results. Properly planned treatment gives satisfactory results.  相似文献   
3.
4.
Summary The purpose of this study was to determine the effects of short-term exercise cessation on lipid and lipoprotein profile and insulin sensitivity in highly trained runners (n=12; mean age 19.9 years) and power athletes (n=12; mean age 24.4 years). Following 14 days of exercise cessation, running time to exhaustion and maximal oxygen uptake decreased by 9.2% and 4.8% (P < 0.05) in the runners, while in the power athletes one repetition maximum squat and bench press did not change (P>0.05). No changes occurred in body composition. Data from a 2-h oral glucose tolerance test revealed an impairment of the glycemic state in all athletes (P<0.05). In contrast, exercise cessation did not significantly (P>0.05) alter plasma levels of cholesterol, triglycerides, and low density (LDL) and high density lipoprotein (HDL). No changes were observed in HDL2, HDL2b, and HDL3 subfractions, LDL diameter, and qualitative LDL pattern (P>0.05). These data thus suggest that despite a decrease in insulin sensitivity, short-term exercise cessation, independent of exercise mode, was insufficient to alter plasma lipid and lipoprotein profiles in well-trained athletes.  相似文献   
5.
The occurrence of the tropical bedbug (Cimex hemipterus Fabricius) in poultry houses in Israel is described. Despite the heavy infestation serious losses have not been registered and no clinical signs observed. Treatment of the barns and accessories with 2% malathion emulsion gave good results. The parasite invaded human habitations as well.  相似文献   
6.
Bridging of nerve gaps is still a major problem in peripheral nerve surgery. Alternatively to autologous nerve grafts tissue engineering of peripheral nerves focuses on biocompatible conduits to reconstruct nerves. Such non-neural conduits fail to support regeneration over larger gaps due to lacking viable Schwann cells that promote regeneration by producing growth factors and cell guiding molecules. This problem may be overcome by implantation of cultivated Schwann cells into suitable scaffolds. In the present experiments we tested a collagen type I/III tube as a potential nerve guiding matrix. Revascularization, tolerance and Schwann cell settlement were evaluated by light, fluorescence and scanning electron microscopy after different implantation times. The conduits were completely revascularized between day 5 and 7 post-operatively and well integrated into the host tissue. Implanted Schwann cells adhered, survived and proliferated on the inner surface of the conduits. Nevertheless, bridging a 2 cm gap of the sciatic nerve of adult Wistar rats with these collagen/Schwann cell conduits led to a disappointing regeneration compared to controls with autologous grafts. From these results, we conclude that a sufficient biocompatibility of bioartificial nerve conduits is a necessary prerequisite, however, it remains only one of several parameters important for peripheral nerve regeneration.  相似文献   
7.
8.
BACKGROUND: The Zuckerkandl's tubercle (ZT) of the thyroid gland is a well-described anatomical landmark, but few studies have clearly defined its association with pressure symptoms. METHODS: Sixty-six consecutive patients who had primary thyroid surgery were prospectively included in the present study between late January and early August 1998. RESULTS: A total of 96 capsular dissections were performed at thyroid surgery. Grades two and three ZT were recognized in 77 (80.2%) dissections. In general 49 (63.6%) of them were associated with significant pressure symptoms. In 43 (87.8%) of the dissections with pressure symptoms, grade 3 ZT was observed (mean weight of goitre: 154.8 g). Interestingly in this group, 16 (37.2%) patients with pressure symptoms had a goitre that was < 100 g and in one patient it was only 21 g. CONCLUSIONS: The pressure symptom of the thyroid gland does not always appear to be due to the large size of the goitre. In a relatively small-size goitre the ZT may cause significant pressure symptoms. Observations in the present study supported a strong association of enlarged ZT with pressure symptoms. We believe this is unlikely to be simply a coincidence but rather a consequence of the enlarged tubercle. Nonetheless a prospective randomized study is called for to allow meaningful and objective evidence to be drawn.  相似文献   
9.
Recycled rubber waste (RW) is produced at an alarming rate due to the deposition of 1.5 billion scrap tires annually around the globe, which causes serious threats to the environment due to its open land filling issues. This study investigates the potential application of RW in concrete structures for mitigating the alkali–silica reaction (ASR). Various proportions of RW (5%, 10%, 15%, 20%, and 25%) partially replaced the used aggregates. RW was procured from a local rubber recycling unit. Cubes, prisms, and mortar bar specimens were prepared using a mixture design recommended by ASTM C1260 and tested for evaluating the compressive and flexural strengths and expansion in an ASR conducive environment for specimens incorporating RW. It was observed that the compressive and flexural strength decreased for specimens incorporating RW compared to that of the control specimens without RW. For example, an 18% and an 8% decrease in compressive and flexural strengths, respectively, were observed for specimens with 5% of RW by aggregates volume at 28 days. Mortar bar specimens without RW showed an expansion of 0.23% and 0.28% at 14 and 28 days, respectively, indicating the potential ASR reactivity in accordance with ASTM C1260. A decrease in expansion was observed for mixtures incorporating RW. Specimens incorporating 20% of RW by aggregate volume showed expansions of 0.17% at 28 days, within the limit specified by ASTM C1260. Moreover, specimens incorporating RW showed a lower reduction in compressive and flexural strengths under an ASR conducive environment compared to that of the control specimen without RW. Micro-structural analysis also showed significant micro-cracking for specimens without RW due to ASR. However, no surface cracks were observed for specimens incorporating RW. It can be argued that the use of RW in the construction industry assists in reducing the landfill depositing issues with the additional benefit of limiting the ASR expansion.  相似文献   
10.
Compressive strength (CS) and splitting tensile strength (STS) are paramount parameters in the design of reinforced concrete structures and are required by pertinent standard provisions. Robust prediction models for these properties can save time and cost by reducing the number of laboratory trial batches and experiments needed to generate suitable design data. Silica fume (SF) is often used in concrete owing to its substantial enhancements of the engineering properties of concrete and its environmental benefits. In the present study, the M5P model tree algorithm was used to develop models for the prediction of the CS and STS of concrete incorporating SF. Accordingly, large databases comprising 796 data points for CS and 156 data records for STS were compiled from peer-reviewed published literature. The predictions of the M5P models were compared with linear regression analysis and gene expression programming. Different statistical metrics, including the coefficient of determination, correlation coefficient, root mean squared error, mean absolute error, relative squared error, and discrepancy ratio, were deployed to appraise the performance of the developed models. Moreover, parametric analysis was carried out to investigate the influence of different input parameters, such as the SF content, water-to-binder ratio, and age of the specimen, on the CS and STS. The trained models offer a rapid and accurate tool that can assist the designer in the effective proportioning of silica fume concrete.  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-23

京公网安备 11010802026262号