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   23975篇
  免费   1537篇
  国内免费   158篇
耳鼻咽喉   292篇
儿科学   753篇
妇产科学   709篇
基础医学   2414篇
口腔科学   703篇
临床医学   1997篇
内科学   5240篇
皮肤病学   508篇
神经病学   1099篇
特种医学   797篇
外国民族医学   9篇
外科学   4303篇
综合类   698篇
现状与发展   1篇
一般理论   21篇
预防医学   1664篇
眼科学   708篇
药学   2107篇
中国医学   156篇
肿瘤学   1491篇
  2023年   290篇
  2022年   944篇
  2021年   1402篇
  2020年   739篇
  2019年   934篇
  2018年   1244篇
  2017年   752篇
  2016年   774篇
  2015年   865篇
  2014年   1076篇
  2013年   1319篇
  2012年   1816篇
  2011年   1856篇
  2010年   958篇
  2009年   788篇
  2008年   1162篇
  2007年   1252篇
  2006年   1092篇
  2005年   946篇
  2004年   891篇
  2003年   752篇
  2002年   694篇
  2001年   328篇
  2000年   315篇
  1999年   291篇
  1998年   157篇
  1997年   114篇
  1996年   101篇
  1995年   106篇
  1994年   69篇
  1993年   54篇
  1992年   130篇
  1991年   120篇
  1990年   114篇
  1989年   103篇
  1988年   97篇
  1987年   94篇
  1986年   97篇
  1985年   85篇
  1984年   68篇
  1983年   87篇
  1982年   35篇
  1981年   44篇
  1980年   32篇
  1979年   78篇
  1978年   44篇
  1977年   52篇
  1976年   41篇
  1975年   44篇
  1974年   38篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
971.
Sleep and Breathing - Migraines are associated with multiple comorbidities like depression, anxiety, poor sleep quality, and subjective cognitive impairment (SCI). This study aimed to evaluate the...  相似文献   
972.
973.
974.
975.
Background and study aimsPatients with non-alcoholic fatty liver disease (NAFLD) exhibit features of metabolic syndrome, including a high body mass index, central obesity, high blood pressure, and abnormal lipid profile values. Orlistat, an intestinal lipase enzyme inhibitor, improves insulin resistance. We aimed to investigate the effects of short-term therapy with orlistat on the components of metabolic syndrome associated with NAFLD and explore its effect on liver fibrosis scores.Patients and methodsAn open-label placebo-controlled clinical study using orlistat for 12 weeks was carried out on 50 patients with NAFLD. They were divided into a placebo group (Group I) and an orlistat treatment group (120 mg per day, Group II). The diagnosis of NAFLD was made by ultrasonography and laboratory investigations. Anthropometric and blood pressure measurements and hepatic liver enzymes, fasting lipids, and blood glucose levels were determined before and after treatment. Lipid indices including cholesterol (Chol-I), triglyceride (TG-I), triglyceride-glucose (TYG-I), and the scores for lipid fibrosis using the NAFLD fibrosis score (NFS) and Fibrosis-4 score (Fib-4) were also determined.ResultsOrlistat significantly improved the anthropometric and metabolic indices (TG-I, TYG-I) and liver enzymes. Orlistat demonstrated a favorable impact on the NAS and Fib-4 scores for liver fibrosis.ConclusionOrlistat improves the components of metabolic syndrome, leading to the improvement of insulin resistance and thereby improves fatty infiltration of the liver. To a lesser extent, orlistat improved the liver fibrosis scores.  相似文献   
976.
977.
978.
Chikungunya virus (CHIKV) is a mosquito‐borne alphavirus. Recent outbreaks of CHIKV infections have been reported in Asia, Africa, and Europe. The symptoms of CHIKV infection include fever, headache, nausea, vomiting, myalgia, rash, and chronic persistent arthralgia. To date, no vaccines or selective antiviral drugs against this important emerging virus have been reported. In this study, the design, synthesis, and antiviral activity screening of new topographical peptidomimetics revealed three potential prototype agents 3a , 4b, and 5d showing 93–100% maximum inhibition of CHIKV replication in cell‐based assay having EC90 of 8.76–9.57 μg/mL. Intensive molecular modeling studies including covalent docking, lowest unoccupied molecular orbital energies, and the atomic condensed Fukui functions calculations strongly suggested the covalent binding of peptidomimetics 3a , 4b, and 5d to CHIKV nsP2 protease leading to permanent enzyme inactivation via Michael adduct formation between α/β‐unsaturated ketone functionality in our designed peptidomimetics and active site catalytic cysteine1013. Furthermore, small molecular weight peptidomimetics 3a and 4b satisfied the Lipinski rule of five for drug‐likeness and showed promising intestinal absorption and aqueous solubility via computational admet studies making them promising hits for further optimization.  相似文献   
979.
Laser-assisted high speed milling is a subtractive machining method that employs a laser to thermally soften a difficult-to-cut material’s surface in order to enhance machinability at a high material removal rate with improved surface finish and tool life. However, this machining with high speed leads to high friction between workpiece and tool, and can result in high temperatures, impairing the surface quality. Use of conventional cutting fluid may not effectively control the heat generation. Besides, vegetable-based cutting fluids are invariably a major source of food insecurity of edible oils which is traditionally used as a staple food in many countries. Thus, the primary objective of this study is to experimentally investigate the effects of water-soluble sago starch-based cutting fluid on surface roughness and tool’s flank wear using response surface methodology (RSM) while machining of 316 stainless steel. In order to observe the comparison, the experiments with same machining parameters are conducted with conventional cutting fluid. The prepared water-soluble sago starch based cutting fluid showed excellent cooling and lubricating performance. Therefore, in comparison to the machining using conventional cutting fluid, a decrease of 48.23% in surface roughness and 38.41% in flank wear were noted using presented approach. Furthermore, using the extreme learning machine (ELM), the obtained data is modeled to predict surface roughness and flank wear and showed good agreement between observations and predictions.  相似文献   
980.
Considering the fungicidal threat to the sustainable agro-environment, the toxicological impacts of three fungicides, namely kitazin, hexaconazole and carbendazim, on the biological, chemical and morpho-anatomical changes of peas were assessed. Fungicide applications in general caused a slow but gradual reduction in growth, symbiosis and yields of peas, which, however, varied appreciably among species and concentrations of the three fungicides. Of the three fungicides, carbendazim had the most lethal effect, in which it delayed seed germination and also diminished the overall pea growth. Carbendazim at 3000 μg kg−1 maximally reduced the germination, SVI, size of roots and shoots and total dry matter accumulation in roots, shoots and whole plants distinctly by 40%, 84%, 72%, 73%, 68%, 75% and 73% (p ≤ 0.05), respectively. Hexaconazole at 120 μg kg−1 significantly (p ≤ 0.05) declined total chlorophyll, carotenoids, grain yields, grain protein, root P and shoot N by 19%, 28%, 46%, 69%, 48% and 51%, respectively, over the control. The synthesis of stress biomarkers and oxidative stress were increased with increasing dosage rates of fungicides. Proline content in roots, shoots, leaves and grains, MDA, electrolyte leakage and H2O2 of plants grown in soil treated with 288 μg kg−1 kitazin were increased significantly (p ≤ 0.05) by 73%, 52%, 41%, 24%, 59%, 40% and 27%, respectively, relative to the control. Antioxidant defence enzymes were greater in pea foliage. The SEM and CLSM images revealed an obvious alteration in root tips, enhanced cellular damage and cell death when plants were raised under fungicide stress. Also, morpho-anatomical variations in fungicide-treated foliage were visible in the SEM images. Overall, the present study suggests that a careful and secure strategy should be adopted before fungicides are chosen for enhancing pulse production in different agro-climatic regions.

Considering the fungicidal threat to the sustainable agro-environment, the toxicological impacts of three fungicides, namely kitazin, hexaconazole and carbendazim, on the biological, chemical and morpho-anatomical changes of peas were assessed.  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