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   908篇
  免费   37篇
  国内免费   15篇
耳鼻咽喉   6篇
儿科学   41篇
妇产科学   8篇
基础医学   158篇
口腔科学   20篇
临床医学   128篇
内科学   131篇
皮肤病学   21篇
神经病学   32篇
特种医学   146篇
外科学   96篇
综合类   20篇
预防医学   40篇
眼科学   12篇
药学   48篇
中国医学   9篇
肿瘤学   44篇
  2021年   10篇
  2018年   12篇
  2017年   7篇
  2016年   9篇
  2015年   15篇
  2014年   11篇
  2013年   15篇
  2012年   12篇
  2011年   32篇
  2010年   31篇
  2009年   39篇
  2008年   31篇
  2007年   38篇
  2006年   26篇
  2005年   37篇
  2004年   28篇
  2003年   25篇
  2002年   21篇
  2001年   24篇
  2000年   21篇
  1999年   14篇
  1998年   21篇
  1997年   37篇
  1996年   22篇
  1995年   22篇
  1994年   16篇
  1993年   9篇
  1992年   21篇
  1991年   20篇
  1990年   26篇
  1989年   27篇
  1988年   21篇
  1987年   31篇
  1986年   18篇
  1985年   20篇
  1983年   13篇
  1982年   9篇
  1981年   10篇
  1980年   13篇
  1979年   8篇
  1978年   8篇
  1977年   11篇
  1976年   14篇
  1975年   9篇
  1973年   10篇
  1972年   8篇
  1970年   9篇
  1969年   8篇
  1967年   10篇
  1966年   11篇
排序方式: 共有960条查询结果,搜索用时 15 毫秒
11.
The results of treatment of 63 injured persons with thoracicoabdominal trauma were analyzed. Injured persons with severe trauma and pronounced infringements of hemodynamic (41.25%); with severe injury of inferior organs and stable hemodynamical indexes (47.62%), light injury (11.12%) were detailed. Algorithm of curative-diagnostical measures for every group was elaborated. Among the injured persons 11 (17.46%) died.  相似文献   
12.
Five new triterpene glycosides, liouvillosides A1 (1), A2 (2), A3 (3), B1 (4), and B2 (5), have been isolated from the Antarctic sea cucumber Staurocucumis liouviellei along with the known liouvilloside A(6), isolated earlier from the same species, and hemoiedemosides A (7) and B (8), isolated earlier from the Patagonian sea cucumber Hemioedema spectabilis. The isolation was carried out using a new chromatographic procedure including application of ion-pair reversed-phase chromatography followed by chiral chromatography on a cyclodextrin ChiraDex column. The structures of the new glycosides were elucidated using extensive NMR spectroscopy (1H and 13C NMR spectrometry, DEPT, 1H-(1)H COSY, HMBC, HMQC, and NOESY), ESI-FTMS, and CID MS/MS, and chemical transformations. Glycosides 1-3 are disulfated tetraosides and glycosides 4 and 5 are trisulfated tetraosides. Glycosides 2 and 3 contain 3-O-methylquinovose, found for the first time as a natural monosaccharide in sea cucumber glycosides. On the basis of analyses of glycoside structures a taxonomic revision is proposed.  相似文献   
13.
Aims:  Gastrointestinal stromal tumours (GISTs) display genetic alterations on chromosome 22. GTn repeat (GTn) length polymorphism in the promoter of haeme oxygenase-1 gene ( HMOX-1 ) is located on chromosome 22 and associated with malignant growth. The aim was to investigate the role of HMOX-1 promoter polymorphism in GIST patients.
Methods and results:  Tumour and corresponding healthy tissue DNA of 44 patients who underwent surgical resection of GIST were analysed by polymerase chain reaction, capillary electrophoresis and DNA sequencing. GTn polymorphism was classified into short (S) and long (L) allele. There was no difference detected in GTn genotype between tumour and healthy tissue DNA. Short GTn allele (SGTn) was significantly associated with metastatic disease, higher tumour recurrence rates and high risk GIST (consensus criteria 2001). Furthermore, SGTn allele carriers had significantly shorter disease-free and overall survival (log rank test, P  < 0.0001). On multivariate Cox regression analysis, GTn polymorphism was identified as an independent prognostic factor for survival ( P  = 0.001).
Conclusions:  HMOX-1 promoter GTn polymorphism is a potential prognostic marker and may help to allocate patients to different risk groups, customized therapy and follow-up. Haeme oxygenase-1 could represent an important candidate gene in the pathogenesis and growth of GIST.  相似文献   
14.
15.
16.
We have evaluated the fibrinogen/fibrin fragment E antigen assay as a diagnostic test in patients with clinically suspected venous thrombosis by comparing the results of this assay with venography in 272 patients. The result of the fragment E antigen assay was elevated in 79 of 80 patients with positive venograms for recent venous thrombosis (sensitivity 99%) and within the normal range in 161 of 192 patients with normal venograms (specificity 84%). The fragment E assay was also evaluated in 130 medical and surgical controls without evidence of venous thrombosis by leg scanning and the test was found to be relatively nonspecific. However, in the patient group under study, a correct clinical diagnosis of no thrombosis, based on a normal fragment E result, was made in 161 of 162 cases (negative predictive value of 99%). Therefore, a normal test result effectively excludes a diagnosis of venous thrombosis in clinically symptomatic patients. The assay, as currently performed, is technically demanding and takes 24 hr to complete. Therefore, it will have to be simplified before it can be applied to clinical practice.  相似文献   
17.
To examine the distribution and physiological role of CO2/pH-sensitive chemoreceptors in the gills of the tropical fish, traira (Hoplias malabaricus), fish were exposed to acute environmental hypercarbia (1.25, 2.5 and 5.0% CO2 in air) and subjected to injections of HCl into the ventral aorta and buccal cavity. This was done before and after selective denervation of branchial branches of the IXth and Xth cranial nerves to various gills arches. Hypercarbia produced a significant decrease in heart rate, a mild hypotension as well as increases in both ventilation rate and ventilation amplitude. The data suggest that the hypercarbic bradycardia and increase in ventilation frequency arise from receptors exclusively within the gills but present on more than the first gill arch, while extra-branchial receptors may also be involved in controlling the increase in ventilation amplitude. With the exception of a decrease in heart rate in response to HCl injected into the ventral aorta, the acid injections (internal and external) did not mimic the cardiorespiratory responses observed during hypercarbia suggesting that changes in CO2 are more important than changes in pH in producing cardiorespiratory responses. Finally, the data indicate that chemoreceptors sensitive to CO2/pH and to O2 in the gills of this species involved in producing ventilatory responses are distributed in a similar fashion, but that those involved in producing the bradycardia are not.  相似文献   
18.
Oral Diseases (2012) 19 , 46–58 Sjögren’s syndrome (SjS) is one of the most common autoimmune rheumatic diseases, clinically characterized by xerostomia and keratoconjunctivitis sicca. We investigated the following controversial topics: (i) Do we have reliable ways of assessing saliva production? (ii) How important are the quantity and quality of saliva? (iii) Are only anti‐SSA/Ro and anti‐SSB/La relevant for the diagnosis of SjS? (iv) Are the American‐European Consensus criteria (AECC) the best way to diagnose SjS? Results from literature searches suggested the following: (i) Despite the fact that numerous tests are available to assess salivation rates, direct comparisons among them are scarce with little evidence to suggest one best test. (ii) Recent developments highlight the importance of investigating the composition of saliva. However, more research is needed to standardize the methods of analysis and collection and refine the quality of the accumulating data. (iii) In addition to anti‐Ro/La autoantibodies, anti α‐fodrin IgA and anti‐MR3 autoantibodies seem to be promising diagnostic markers of SjS, but more studies are warranted to test their sensitivity and specificity. (iv) AECC are classification, not diagnostic criteria. Moreover, recent innovations have not been incorporated into these criteria. Consequently, treatment directed to patients diagnosed using the AECC might exclude a significant proportion of patients with SjS.  相似文献   
19.
Several animal studies indicate that mercury is a male reproductive toxicant, but human studies are few and contradictory. We examined semen characteristics and serum levels of reproductive hormones in relation to environmental exposure to mercury. Blood and semen samples were collected from 529 male partners of pregnant women living in Greenland, Poland and Ukraine between May 2002 and February 2004. The median concentration of the total content of mercury in whole blood was 9.2 ng ml−1 in Greenland (0.2–385.8 ng ml−1), 1.0 ng ml−1 in Poland (0.2–6.4 ng ml−1) and 1.0 ng ml−1 in Ukraine (0.2–4.9 ng ml−1). We found a significantly positive association between the blood levels of mercury and serum concentration of inhibin B in men from Greenland (β=0.074, 95% confidence interval (CI)=0.021 to 0.126) and in an analysis including men from all three regions (β=0.067, 95% CI=0.024 to 0.110). The association may be due to beneficial effects of polyunsaturated fatty acids (PUFAs), which are contained in seafood and fish. No significant association (P>0.05) was found between blood concentrations of mercury and any of the other measured semen characteristics (semen volume, total sperm count, sperm concentration, morphology and motility) and reproductive hormones (free androgen index (FAI), follicle-stimulating hormone (FSH), luteinizing hormone (LH), testosterone and LH×testosterone) in any region. In conclusion, the findings do not provide evidence that environmental mercury exposure in Greenlandic and European men with median whole blood concentration up to 10 ng ml−1 has adverse effects on biomarkers of male reproductive health.  相似文献   
20.
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