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   15658篇
  免费   105篇
  国内免费   78篇
教育   11131篇
科学研究   2108篇
各国文化   23篇
体育   552篇
综合类   220篇
文化理论   421篇
信息传播   1386篇
  2024年   11篇
  2023年   6篇
  2022年   53篇
  2021年   101篇
  2020年   78篇
  2019年   57篇
  2018年   2216篇
  2017年   2133篇
  2016年   1608篇
  2015年   262篇
  2014年   311篇
  2013年   322篇
  2012年   510篇
  2011年   1011篇
  2010年   1120篇
  2009年   700篇
  2008年   892篇
  2007年   1426篇
  2006年   355篇
  2005年   655篇
  2004年   581篇
  2003年   517篇
  2002年   298篇
  2001年   169篇
  2000年   123篇
  1999年   89篇
  1998年   49篇
  1997年   60篇
  1996年   33篇
  1995年   13篇
  1994年   16篇
  1993年   12篇
  1992年   13篇
  1991年   13篇
  1990年   9篇
  1989年   5篇
  1988年   1篇
  1987年   1篇
  1986年   2篇
  1985年   1篇
  1984年   2篇
  1981年   2篇
  1979年   2篇
  1976年   1篇
  1975年   1篇
  1974年   1篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
Prevalence of diabetes mellitus, a chronic metabolic disease characterized by hyperglycemia, is growing worldwide. The majority of the cases belong to type 2 diabetes mellitus (T2DM). Globally, India ranks second in terms of diabetes prevalence among adults. Currently available classes of therapeutic agents are used alone or in combinations but seldom achieve treatment targets. Diverse pathophysiology and the need of therapeutic agents with more favourable pharmacokinetic-pharmacodynamics profile make newer drug discoveries in the field of T2DM essential. A large number of molecules, some with novel mechanisms, are in pipeline. The essence of this review is to track and discuss these potential agents, based on their developmental stages, especially those in phase 3 or phase 2. Unique molecules are being developed for existing drug classes like insulins, DPP-4 inhibitors, GLP-1 analogues; and under newer classes like dual/pan PPAR agonists, dual SGLT1/SGLT2 inhibitors, glimins, anti-inflammatory agents, glucokinase activators, G-protein coupled receptor agonists, hybrid peptide agonists, apical sodium-dependent bile acid transporter (ASBT) inhibitors, glucagon receptor antagonists etc. The heterogeneous clinical presentation and therapeutic outcomes in phenotypically similar patients is a clue to think beyond the standard treatment strategy.  相似文献   
72.
73.
Fungi are non-chlorophyllus microorganisms, which constitutes the main source of outdoor and indoor allergens. The antigens present in the spores and fragments of hyphae induce allergic responses in sensitized patients. The frequently recognized fungi associated with asthma include Alternaria, Cladosporium, Aspergillus, and Penicillium. With the advent of molecular biology techniques a number of fungal genes encoding relevant allergens have been cloned and the expressed allergens purified and characterized. In this review, we have presented the recent developments, where recombinant allergens have been used in the precise diagnosis of fungal allergy. We have also discussed the role played by these allergens and the T- and B-cell epitopes in the immune mechanism in fungal allergy.  相似文献   
74.
Pre analytical process of extraction for accurate detection of organic acids is a crucial step in diagnosis of organic acidemias by GCMS analysis. This process is accomplished either by solid phase extraction (SPE) or by liquid–liquid extraction (LLE). Both extraction procedures are used in different metabolic laboratories all over the world. In this study we compared these two extraction procedures in respect of precision, accuracy, percent recovery of metabolites, number of metabolites isolated, time and cost in a resource constraint setup. We observed that the mean recovery from SPE was 84.1 % and by LLE it was 77.4 % (p value <0.05). Moreover, the average number of metabolites isolated by SPE and LLE was 161.8 ± 18.6 and 140.1 ± 20.4 respectively. The processing cost of LLE was economical. In a cost constraint setting using LLE may be the practical option if used for organic acid analysis.  相似文献   
75.
Proficiency of laboratory services is the mainstay in clinical medicine in providing error free diagnostic results. The efficiency of the laboratory needs to be evaluated as per standard international criterion. The quality indicators of the different phases of total testing process are considered the fundamental measurable tool for evaluation of laboratory performance. In order to optimize the laboratory’s proficiency and accreditate it as per international standard in our newly established lab, the study was conducted to evaluate the frequency of errors incurred by laboratory and nonlaboratory professionals during the whole testing process. Retrospective analysis was done for data received from April 2016 to Dec 2016 in our lab. Total number of samples received was 61,674, out of which 43200 samples could be analyzed for quality indicators. Total numbers of tests processed in these samples were 172,800. In the study samples, 26.5% errors were due to pre-analytical factors whereas 9.4% of errors were contributed by analytical phase and 18% by post-analytical phase. Inappropriateness of test requisition was observed to be the major attributing determinant for pre-analytical errors. Instrumentation efficiency in form of frequent breakdown (~7%), greatly affected the proficiency of analytical phase in our lab. 12% of post-analytical errors were ascribed by excessive turn-around-time. However, timeliness of critical value call out and reporting for STAT samples revealed high proficiency up to 97%. High error rates were observed in pre–pre- and pre-analytical phases that also accorded for high error frequency in post analytical phase. This emphasizes urgent need to formulate guidelines for processing all steps of total testing process and initiate strategic measures for reducing risk of errors and increasing patient safety.  相似文献   
76.
77.
This study is conducted in chronic alcoholics to assess the association of an Individual’s level of serum homocysteine with the success of achieving alcohol deaddiction in the patient. The patients’ nutrition status is also assessed. 50 chronic alcoholics admitted to a deaddiction center were inducted into the study. Patients underwent an 8 weeks holistic program to promote rehabilitation from alcoholism. All the patients were addicted to alcohol for 8 – 10 years. Of the 50 patients enrolled, 39 of them completed the 8 weeks program including complete abstinence from alcohol during this period. Fasting blood samples were collected on admission and again after 8 weeks of alcohol abstinence for analyses of serum homocysteine and serum prealbumin, transferrin, total proteins and albumin, gammaglutamyl transferase (GGT) and alanine transaminase (ALT). Of the 50 patients enrolled in the study, 39 completed the 8 weeks rehabilitation program. 11 patients discontinued within 2 weeks of admission. During the 8 weeks of complete alcohol abstinence, patients were given a balanced diet and multivitamin supplements. A significant improvement in their nutritional status was noted by the elevation of serum levels of prealbumin, transferrin, total proteins and albumin. Serum homocysteine levels decreased significantly (p<0.002) to normal levels from previous hyperhomocytenemia. This was accompanied by decrease in serum GGT and ALT levels indicating improved liver functions. Serum estimation of homocysteine in chronic alcoholics is important to assess whether the patient will have a successful rehabilitation. Normal homocysteine levels are achieved after dietary changes and abstinence from alcohol. Timely correction of hyperhomocysteinemia also provides successful rehabilitation.  相似文献   
78.
P-selectin, a cell adhesion molecule is elevated in many inflammatory conditions including preeclampsia which is characterized by generalized endothelial dysfunction and vasoconstriction presumably due to free radicals or mediators released by defective placentation. Vitamin E has been documented to protect cell membranes from oxidative damage and also decrease platelet aggregation. The role of vitamin E in pre-eclampsia is contradictory and hence the study was undertaken. Soluble P-selectin was measured by ELISA and Vitamin-E levels in plasma was estimated spectrofluorometrically. In our study the effect of supplementation of 400 IU/day of Vitamin E (a-tocopheryl acetate) to patients of pre-eclampsia showed significant decreased levels of soluble P-selectin by 2nd week as compared to patients given placebo (P = 0.005). In this short period of study no direct correlations were observed between Vitamin E or P-selectin levels with blood pressure as well as with proteinuria. Future studies may focus on the effect of a-tocopheryl acetate or the phosphate form of Vitamin-E, recently proposed to be the more active form on other inflammatory markers like IL-6, an important stimuli of P-selectin release in pre-eclampsia.  相似文献   
79.
Susceptibility of Schizophrenic patients to lipid peroxidation relative to healthy control subjects was investigated by measuring the malondialdehyde (MDA) levels in plasma. The main finding was that Schizophrenic patients were more susceptible than control subjects to oxidative damage as evident from increased MDA levels in plasma. Antioxidant levels are also depleted in Schizophrenic patients when compared to normal subjects as evident from decreased levels of vitamins E and C in the plasma. Impaired antioxidant defense and increased lipid peroxidation suggests that treatment with antioxidants (Vitamin E, Vitamin C, beta carotene) at the initial stages of illness may prevent further oxidative injury and deterioration of associated neurological deficits in Schizophrenia.  相似文献   
80.
This study was undertaken to evaluate the role of serum neuron specific enolase (NSE) in prediction of disability and neurological worsening in hypertensive ischemic cerebrovascular stroke. 80 hypertensive ischemic stroke patients diagnosed by a neurologist as per WHO definition along with radiological findings suggestive of cerebrovascular stroke and differentiating from hemorrhagic stroke and 60 controls having essential hypertension coming to hospital because of regular checkup or headache but with no neurological disease were included in the study. Neurological disability was assessed by NIHSS at the time of admission (within 72 h from the onset of stroke) and on 7th day after admission and cases were categorized into mild, moderate and severe disability. Venous blood samples were drawn within 72 h from the onset of symptoms. The samples were processed as per the laboratory protocol. The serum NSE samples were analyzed using an enzyme immunoassay based on the sandwich technique. We observed raised serum NSE in hypertensive ischemic stroke (17.4 ± 5.4 ng/ml) with significant association between different hypertensive groups than in hypertensive controls (9.1 ± 0.75 ng/ml). Greater degree of disability was observed in hypertensive stroke patients with raised serum NSE and hypertensive patients with mean serum NSE level of 22.9 ± 3.6 ng/ml and dyslipidemia had greater probability of neurological worsening as compared to those with mean serum NSE level of 12.7 ± 1.2 ng/ml. Serum NSE levels can serve as a peripheral indicator of neuronal damage and assist in the prediction of disability and clinical outcome in hypertensive cerebrovascular ischemic stroke patients.  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