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   1706篇
  免费   112篇
  国内免费   4篇
耳鼻咽喉   21篇
儿科学   38篇
妇产科学   50篇
基础医学   177篇
口腔科学   16篇
临床医学   164篇
内科学   388篇
皮肤病学   39篇
神经病学   75篇
特种医学   60篇
外科学   356篇
综合类   30篇
一般理论   1篇
预防医学   107篇
眼科学   90篇
药学   97篇
中国医学   15篇
肿瘤学   98篇
  2024年   5篇
  2023年   17篇
  2022年   59篇
  2021年   92篇
  2020年   34篇
  2019年   69篇
  2018年   61篇
  2017年   39篇
  2016年   53篇
  2015年   62篇
  2014年   79篇
  2013年   91篇
  2012年   110篇
  2011年   103篇
  2010年   71篇
  2009年   62篇
  2008年   102篇
  2007年   101篇
  2006年   97篇
  2005年   91篇
  2004年   89篇
  2003年   56篇
  2002年   46篇
  2001年   30篇
  2000年   30篇
  1999年   30篇
  1998年   10篇
  1997年   8篇
  1996年   7篇
  1995年   7篇
  1994年   5篇
  1993年   4篇
  1992年   12篇
  1991年   6篇
  1990年   10篇
  1989年   5篇
  1987年   10篇
  1986年   15篇
  1984年   7篇
  1982年   4篇
  1981年   2篇
  1980年   3篇
  1979年   5篇
  1978年   2篇
  1977年   2篇
  1970年   6篇
  1968年   2篇
  1963年   1篇
  1935年   1篇
  1927年   2篇
排序方式: 共有1822条查询结果,搜索用时 15 毫秒
1.
The present investigation was aimed at studying the possible role of curcumin against N-nitrosodiethylamine (NDEA)-induced toxicity in albino rats. Administration of NDEA to rats at a concentration of 0.1 mg/ml in drinking water ad libitum for 21 days produced toxicity in them, which was evident from histopathological changes in the rat livers, and increased levels of blood serum enzyme markers, i.e. aspartate transaminase, alanine transaminase, alkaline phosphatase, and lactate dehydrogenase. In addition, the levels of oxidative stress markers like lipid peroxidation (LPO), protein carbonyl (PCC), and glutathione-S-transferase (GST) activity were elevated and the total glutathione (GSH) content was reduced in the livers. The administration of curcumin to rats at concentrations of 10, 20, and 40 mg/ml in drinking water along with 0.1 mg/ml of NDEA for 21 days effectively suppressed NDEA-induced toxicity and also resulted in a dose-dependent reduction in the levels of blood serum enzyme markers (AST, ALT, ALP, and LDH). Moreover, LPO, PCC, and GST activity were reduced and the GSH level was increased upon the administration of curcumin along with NDEA. The results obtained for the comet assay in rat hepatocytes and blood lymphocytes showed a significant dose-dependent decrease in the mean tail length. The micronucleus assay performed on rat hepatocytes also showed a dose-dependent reduction in the frequency of micronucleated cells along with curcumin administration. These results suggest that curcumin has a protective role against NDEA-induced toxicity in albino rats.  相似文献   
2.
3.
Near-surface or shallow land disposal of radioactive waste has been the primary practice at the Pakistan Institute of Nuclear Science and Technology (PINSTECH). The adopted choice of this mode of disposal has been based on a study of the site and the quality and quantity of waste generated at the 5 MW reactor with HEU fuel. Specific measures regarding the radiation safety of the workers and environmental protection have been adopted. The waste disposal operations are conducted to meet local regulatory requirements, IAEA recommendations and internationally endorsed principles such as ALARA (as low as reasonably achievable - economic, social and other relevant factors being considered). The data obtained through the years of operational and management experience have manifested the robustness of the disposal system and reliability of the disposal criterion, and have also served to further refine the latter. Consequently, confidence in the current shallow-land-burial practices has increased. Radiological safety of these practices has been assessed by addressing different aspects of the safety and disposal system. These parameters, as indices of a non-exclusive and operational safety model, are presented.  相似文献   
4.
100 cases of either sex 96 males and 4 females in their mean age group of 45 year ± 14.51 standard deviation were selected for this study to analyse the Hearing Acuity in the post spinal analgesia period during a period of eight months in the E.N.T department of the J.N. Medical College A.M.U. Aligarh. The size of the needle used for spinal analgesia was 22G and the equipment for Audiometry was the pure tone Audiometer. Pure tone Audiometry was done pre-operatively and then on the 1st, 3rd, 5th and 12th subsequent post-operative days and then after six months. It was found that 12% of the patients showed incidence of mild hearing loss. However, the loss was transient, reversible, within low frequency range (250, 500, 1000 Hz), and no patient suffered from any permanent hearing loss.  相似文献   
5.
Abstract: In order to determine the pulmonary toxicity of kerosene and its ignition product (soot) in asbestos exposed subjects, the activities of phase I and phase II drug metabolizing enzymes in rat lungs after single intratracheal coexposure to Indian chrysotile asbestos and kerosene or its soot and Indian chrysotile were assayed. Exposure to kerosene or its soot resulted in a significant increase in the level of microsomal cytochrome P-450 and the activity of P-450 dependent monooxygenase, benzo(a)pyrene hydroxylase, as well as in the activities of microsomal epoxide hydrase and cytosolic glutathione-S-transferase (GST). However, in chrysotile exposed animals a reverse pattern in these parameters was recorded. The co-exposure to chrysotile and kerosene or chrysotile and soot led to a significant depletion in cytochrome P-450 level and a decrease in the activities of benzo(a)pyrene hydroxylase, epoxide hydrase and GST when compared to kerosene and soot controls, respectively. These results suggest that asbestos by altering the pulmonary drug metabolizing enzyme system may increase the toxic potential of kerosene and its ignition product in the respiratory system.  相似文献   
6.
7.
8.
OBJECTIVES: To illustrate the types of injuries seen by the accident and emergency department as a result of the use of non-motorized 'microscooters' in children, and to increase awareness of scooter-related triplane fractures of the ankle. STUDY DESIGN: A retrospective study conducted in an accident and emergency department of a district general hospital on all children who had a scooter-related limb injury over a 6-month period and were referred for orthopaedic review. METHODS: The analysis involved a case note review. Information recorded included the injury sustained, protective equipment worn at the time of the accident and management by the orthopaedic team. RESULTS: Scooter injuries accounted for 10 fractures in this period. There were three 'triplanar' injuries, which required operative fixation, and three injuries requiring manipulation under anaesthesia. No protective gear was worn by any of the patients. CONCLUSION: The popularity of microscooters seems to represent a significant risk of bony injury in the paediatric population. Medical personnel who manage acute paediatric trauma should be aware of scooter-related triplanar ankle injuries.  相似文献   
9.
Series of new mixed aza-oxo-thia macrocyclic ligands 1,9(2,6)-ditriazina-2,8,10,16-tetraaza-3,7,11,15-tetraoxo-5,13-dithia-cyclohexadecaphan-14,94-diphenyl (L1); 1,10(2,6)-ditri azina-2,9,11,18-tetraaza-3,8,12,17-tetraoxo-5,6,14,15-tetrathia-cyclooctadecaphan-14,104-diphenyl (L2); 1,11(2,6)-ditriazina-2,10,12,20-tetraaza-3,9,13,19-tetraoxo-6,16-dithia-cyclocosa-phan-14,114-diphenyl (L3); 1,12(2,6)-ditriazina-2,11,13,22-tetraaza-3,10,14,21-tetraoxo-6,7,17,18-tetrathia-cyclodocosaphan-14,124-diphenyl (L4) were synthesised. The structural features of the compounds have been studied by elemental analyses, Mass, FT-Raman, FT-IR, 1H and 13C NMR spectroscopy. The antimicrobial activities of the ligands were evaluated using disk diffusion method in dimethyl sulfoxide (DMSO) as well as the minimal inhibitory concentration (MIC) dilution method, against several bacteria and yeast cultures. The obtained results from both methods were assessed in side-by-side comparison with commercial antibacterial and antifungal agents. In most cases, the compounds show strong antifungal activity in the comparison tests. Cytotoxic activities of the ligands against two different human cancer cell lines, stomach (23132/87) and lung (A549) were determined by MTT assay. DNA fragmentation assay tested cell lines were used to analyze the DNA ladder formation which is a characteristic of apoptotic cell death. The binding of the ligands with calf thymus DNA (CT-DNA) has also been investigated by absorption spectroscopy.  相似文献   
10.
Focal uptake of 99mTc-MDP was seen in a case of hepatoblastoma. The focal uptake corresponded to an area of calcification on CT, which was shown histologically to consist of osteoid with mineralization. The mechanism of uptake by the tumor in this case is likely to be the same as for skeletal uptake.  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