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   8656篇
  免费   447篇
  国内免费   44篇
耳鼻咽喉   137篇
儿科学   431篇
妇产科学   284篇
基础医学   888篇
口腔科学   202篇
临床医学   716篇
内科学   2028篇
皮肤病学   153篇
神经病学   603篇
特种医学   256篇
外科学   1678篇
综合类   177篇
一般理论   2篇
预防医学   397篇
眼科学   224篇
药学   508篇
中国医学   33篇
肿瘤学   430篇
  2023年   80篇
  2022年   218篇
  2021年   337篇
  2020年   203篇
  2019年   243篇
  2018年   275篇
  2017年   187篇
  2016年   240篇
  2015年   269篇
  2014年   381篇
  2013年   521篇
  2012年   679篇
  2011年   659篇
  2010年   378篇
  2009年   327篇
  2008年   519篇
  2007年   546篇
  2006年   547篇
  2005年   478篇
  2004年   439篇
  2003年   375篇
  2002年   303篇
  2001年   109篇
  2000年   96篇
  1999年   72篇
  1998年   38篇
  1997年   26篇
  1996年   38篇
  1995年   44篇
  1994年   37篇
  1993年   32篇
  1992年   50篇
  1991年   50篇
  1990年   34篇
  1989年   47篇
  1988年   31篇
  1987年   21篇
  1986年   24篇
  1985年   20篇
  1984年   18篇
  1983年   15篇
  1982年   9篇
  1981年   22篇
  1980年   14篇
  1979年   10篇
  1978年   9篇
  1977年   10篇
  1973年   9篇
  1972年   6篇
  1967年   12篇
排序方式: 共有9147条查询结果,搜索用时 15 毫秒
1.
2.
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   
3.
4.
5.
The first observations of altered metabolism in malignant cells were made nearly 100 years ago and therapeutic strategies targeting cell metabolism have been in clinical use for several decades.  In this review, we summarize our current understanding of cell metabolism dysregulation in childhood acute lymphoblastic leukemia (cALL). Reprogramming of cellular bioenergetic processes can be expected in the three distinct stages of cALL: at diagnosis, during standard chemotherapy, and in cases of relapse. Upregulation of glycolysis, dependency on anaplerotic energy sources, and activation of the electron transport chain have all been observed in cALL. While the current treatment strategies are tackling some of these aberrations, cALL cells are likely to be able to rewire their metabolism in order to escape therapy, which may contribute to a refractory disease and relapse. Finally, here we focus on novel therapeutic approaches emerging from our evolving understanding of the alterations of different metabolic networks in lymphoblasts.  相似文献   
6.
Low molecular weight heparins are widely used in the prophylaxis and treatment of thrombotic disorders. The effect of low molecular weight heparins on coagulation was examined ultrastructurally in an animal model. A test and a control group was formed, each consisting of five rabbits. Nadroparine (225 Institute of Chaoy Unit/kg twice daily) was applied to the test group for 10 days. The control group received 1 ml saline solution subcutaneously. Blood and vascular tissue samples collected at the end of the 10th day were evaluated under a JEM 100 B electron microscope. Platelet degranulation and agglutination was observed in the control group. Fibrin materials were detected in the cytoplasms and surroundings of degranulated platelets. Erythrocyte accumulation was remarkable on the vascular endothelium with intact coagulation periods. In the test group, outer membranes of platelets, hyalomere, and granular structures in the granulomeres were detected to be nearly intact. There were rare erythrocytes in the large vascular lumens. The aggregation phase had occurred but no agglutination was detected. Nadroparine seems to preserve consistency of lipoprotein membranes of platelets and granular structures containing enzymes, which contribute to the coagulation mechanisms.  相似文献   
7.
In this study, for low atomic number targets and biological compounds, an inelastic mean free path (IMFP) formula and energy straggling parameter formula are presented, being valid for low and high electron energies. In addition, calculation of the continuous slowing down approximation-range (CSDA-range) from the stopping power is also made. The IMFP and the energy straggling parameter formulae are evaluated using the generalized oscillator strength (GOS) model and the exchange correction to the inelastic differential cross section (IDCS) given by Inokuti, M., [1978. Inelastic collisions of fast charged particles with atoms and molecules--the Bethe theory revisited. Rev. Mod. Phys. 50, 23-35]. The IMFP and CSDA-range for the biological compounds C5H5N5 (adenine), C5H5N5O (guanine), C4H5N3O (cytosine), C5H6N2O2 (thymine), C20H27N7O13P2 (cytosine-guanine) and C19H26N8O13P2 (thymine-adenine) have been introduced for incident electrons in the energy range 20 eV-1 MeV. The calculated results are compared with semi-empirical results and other theoretical results, good agreement being found with experimental data and Monte Carlo (PENELOPE code) predictions. All the IMFP versus energy curves exhibit minima around 80 eV.  相似文献   
8.
9.
We hypothesized that increased ambient concentrations of metals, as a consequence of escalating urbanization and industrialization of the Gulf region will respond in increased contamination of edible fish species. In this study, we report concentrations of chromium, manganese, cobalt, copper, zinc, arsenic, cadmium, mercury and lead in meat and liver of wild Red-spot emperor (Lethrinus lentjan) from three sampling points at the UAE coast. Analysis was performed by the ICP-MS/microwave digestion. Our study has shown that meat and liver metal content was significantly higher in areas with higher industrial activity, although metal values did not exceed permitted levels of fish for human consumption.  相似文献   
10.
Fascioliasis is a worldwide zoonotic infection with fasciola hepatica and fasciola gigantica. The zoonoses are particularly endemic in sheep‐raising countries and are also endemic in Turkey. Clinical features of fascioliasis relate to the stage and intensity of infection. Fasciola hepatica infection comprises two stages: hepatic and biliary, with different signs and symptoms. Cholestatic symptoms may be sudden, but, in some cases, they may be preceded by a long period of fever, eosinophilia and vague gastrointestinal symptoms. We reported a case with fever and upper‐quadrant abdominal pain since 3 months that comes from an area endemic for fasciola hepatica, with suspected imaging about fasciola hepatica in common bile duct on ultrasonography. After that, fasciola hepatica was extracted with endoscopic retrograde cholangiography.  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