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   2328篇
  免费   124篇
  国内免费   21篇
耳鼻咽喉   49篇
儿科学   104篇
妇产科学   137篇
基础医学   358篇
口腔科学   36篇
临床医学   131篇
内科学   524篇
皮肤病学   43篇
神经病学   249篇
特种医学   53篇
外科学   178篇
综合类   10篇
一般理论   1篇
预防医学   189篇
眼科学   55篇
药学   229篇
中国医学   5篇
肿瘤学   122篇
  2023年   17篇
  2022年   73篇
  2021年   136篇
  2020年   64篇
  2019年   81篇
  2018年   86篇
  2017年   56篇
  2016年   75篇
  2015年   75篇
  2014年   89篇
  2013年   116篇
  2012年   180篇
  2011年   162篇
  2010年   95篇
  2009年   71篇
  2008年   145篇
  2007年   131篇
  2006年   113篇
  2005年   100篇
  2004年   122篇
  2003年   97篇
  2002年   90篇
  2001年   25篇
  2000年   33篇
  1999年   19篇
  1998年   8篇
  1997年   10篇
  1996年   9篇
  1994年   7篇
  1993年   4篇
  1992年   24篇
  1991年   18篇
  1990年   22篇
  1989年   9篇
  1988年   11篇
  1987年   13篇
  1986年   13篇
  1985年   4篇
  1984年   10篇
  1983年   5篇
  1981年   4篇
  1978年   3篇
  1976年   4篇
  1975年   4篇
  1973年   3篇
  1972年   6篇
  1970年   4篇
  1969年   3篇
  1968年   5篇
  1967年   5篇
排序方式: 共有2473条查询结果,搜索用时 945 毫秒
1.
The current literature suggests that the antibacterial effect of leukocyte- and platelet-rich plasma (L-PRP) is directly related to platelet and leukocyte concentrations. The aim of this study was twofold: first, to evaluate the antimicrobial effect of L-PRP against selected bacterial strains in vitro, and second, to correlate this effect with leukocyte and platelet content in the final concentration. Blood was collected from 20 healthy males, and L-PRP, acellular plasma (AP), and autologous thrombin were consecutively prepared. Flow cytometry analysis of the blood, L-PRP, and AP was performed. The L-PRP gel, liquid L-PRP, and thrombin samples were tested in vitro for their antibacterial properties against seven selected bacterial strains using the Kirby–Bauer disk-diffusion method. There was notable antimicrobial activity against selected bacterial strains. No statistically significant correlations between antimicrobial activities and the platelet concentration in L-PRP were observed. Statistically significant positive correlations between selected leukocyte subtypes and antimicrobial activity were noted. A negative correlation was found between elevated monocyte count and antimicrobial activity of L-PRP against one bacterial strain studied. L-PRP possesses antimicrobial activity and can be potentially useful in the fight against certain postoperative infections. The bactericidal effect of L-PRP is caused by leukocytes, and there exists a relationship among selected leukocyte subtypes and L-PRP antimicrobial activity.  相似文献   
2.
Angiotensin II receptor blockers (ARBs) are widely used for the treatment of hypertension. It is believed that treatment with an ARB increases the level of plasma angiotensin II (Ang II) because of a lack of negative feedback on renin activity. However, Ichikawa (Hypertens Res 2001; 24: 641-646) reported that long-term treatment of hypertensive patients with olmesartan resulted in a reduction in plasma Ang II level, though the mechanism was not determined. It has been reported that angiotensin 1-7 (Ang-(1-7)) potentiates the effect of bradykinin and acts as an angiotensin-converting enzyme (ACE) inhibitor. It is known that ACE2, which was discovered as a novel ACE-related carboxypeptidase in 2000, hydrolyzes Ang I to Ang-(1-9) and also Ang II to Ang-(1-7). It has recently been reported that olmesartan increases plasma Ang-(1-7) through an increase in ACE2 expression in rats with myocardial infarction. We hypothesized that over-expression of ACE2 may be related to a reduction in Ang II level and the cardioprotective effect of olmesartan. Administration of 0.5 mg/kg/day of olmesartan for 4 weeks to 12-week-old stroke-prone spontaneously hypertensive rats (SHRSP) significantly reduced blood pressure and left ventricular weight compared to those in SHRSP given a vehicle. Co-administration of olmesartan and (D-Ala7)-Ang-(1-7), a selective Ang-(1-7) antagonist, partially inhibited the effect of olmesartan on blood pressure and left ventricular weight. Interestingly, co-administration of (D-Ala7)-Ang-(1-7) with olmesartan significantly increased the plasma Ang II level (453.2+/-113.8 pg/ml) compared to olmesartan alone (144.9+/-27.0 pg/ml, p<0.05). Moreover, olmesartan significantly increased the cardiac ACE2 expression level compared to that in Wistar Kyoto rats and SHRSP treated with a vehicle. Olmesartan significantly improved cardiovascular remodeling and cardiac nitrite/ nitrate content, but co-administration of olmesartan and (D-Ala7)-Ang-(1-7) partially reversed this anti-remodeling effect and the increase in nitrite/nitrate. These findings suggest that olmesartan may exhibit an ACE inhibitory action in addition to an Ang II receptor blocking action, prevent an increase in Ang II level, and protect cardiovascular remodeling through an increase in cardiac nitric oxide production and endogenous Ang-(1-7) via over-expression of ACE2.  相似文献   
3.
Authors present a method of esophageal dilatation and report their experiences. The place of esophageal dilatation among other therapeutic approaches of esophageal stricture is discussed. The advantage of Savary-Gilliard bougies and guide wire and its applications are presented. During one and a half year 218 esophageal dilatations were performed at 82 patients. 11 patients were intubated endoscopically. Esophageal perforation occurred in 2 cases (0.93%). Dilatation of the esophagus with Savary-Gilliard bougies and using of the guide wire are considered a safe and many-sided method in the diagnosis and treatment of esophageal strictures.  相似文献   
4.
A Oláh  G Pardavi  T Mátrai 《Orvosi hetilap》1992,133(41):2617-2620
In connection with three successfully operated cases authors are treating the types of late pancreatic complications after blunt abdominal trauma. It is emphasized that the preoperative diagnosis is difficult. Many times weeks or months pass away after the trauma without any symptoms and only developed complication can be noticed first. The importance of the first provision and the need for a careful examination of the pancreas at operation is underlined. In the case of the less suspicion of pancreatic injury they suggest wide, adequate drainage. At last they call attention to the responsibility of the surgeon making the first operation.  相似文献   
5.
A nationwide evaluation of multiple congenital abnormalities in Hungary   总被引:1,自引:0,他引:1  
A population-based study of 7,049 index patients with multiple congenital abnormalities (MCA) born in Hungary during 1973-1982 was organized by the Hungarian Center for Congenital Anomaly Control. All clinically recognized syndromes and associations which were submitted (2,049) were accepted without any further follow-up. New or supplementary information was requested in the case of unspecified MCA (320). A copy of detailed necropsy records was requested from pathologists in lethal cases (2,022). Following these steps, apparent but not true instances of MCA were excluded (399), and an attempt was made to assign as many of the remainder as possible in 17 well-delineated MCA entities (900). The living index patients with severe MCA were referred where possible to the regional centers for evaluation (864). One hundred and seventy entities were identified, and seven cases were excluded as not representing MCA. In the so-called 3,393 unidentified cases for which no diagnosis was possible, the component abnormalities were tabulated according to their number. The final count was 6,643 cases with MCA, which is equivalent to a birth prevalence of 4.0 per 1,000 total births, and to 10% of recorded cases with congenital anomalies. As a result of this program the proportion of recognized syndromes and associations among children with MCA increased from 29% to 47%. The accuracy of diagnoses has improved, e.g., the occurrence of unspecified cases decreased from 4.5% to 2%. As a result of this study, the number of chromosomal (1,700), Mendelian (557), and teratogenic (104) syndromes and associations (758) was considerably greater than the initial notifications indicated.  相似文献   
6.
A 51-year-old woman suffered rapidly irreversible cardiogenic shock with left hemiparesis. Transesophageal echocardiography, which represents an essential imaging tool in the emergency room, ruled out aortic dissection involving branch vessels but did not allow an in vivo diagnosis of spontaneous coronary dissection. The in vivo diagnosis of spontaneous coronary dissection is rather difficult because of the dramatic clinical presentation and selective coronary angiography requirement.  相似文献   
7.
8.
Summary In this report we describe changes in the intracellular redistribution of raf serine/threonine protein kinase (product of the raf proto-oncogene family) in hippocampal neurons following cerebral ischemia in Mongolian gerbils. For immunohistochemical localization studies polyclonal antisera specific for each of the A, B, and Raf-1 isotypes of raf, as well as a pan-raf antisera, were employed. Of these, only sera recognizing B-raf, as well as the general v-raf (raised against the conserved C-terminal region) were positive, indicating that B-raf is the major isotype in this neuronal region. Three different ischemie models were used (repeated 3 times for two min and single 5 or 15 min occlusions, of the common carotid arteries) to demonstrate that ischemie insult causes redistribution of raf protein kinase into the cell nucleus of hippocampal neurons. Increased amounts of raf protein in the nuclei of pyramidal cells following ischemia was confirmed by Western blot analysis of isolated nuclear fractionations. Moreover, an elevation in the level of nuclear raf protein also was detected in the contralateral (i.e. non-occluded hemisphere) neurons of CA1 and CA3 subfields 4 days after the ischemie insult indicating a possible transsynaptic increase in the amount of raf protein along with redistribution. The intranuclear translocation of the immunoreactive material started from the perinucleolar rim and with time extended throughout the nucleus. Enhanced levels and altered redistribution of the raf polypeptide in the nuclei of pyramidal cells of the CA3 subfleld appears to be reversible and returns to the normal level 12 days following the ischemic insult. In addition to triggering the above changes in the intracellular redistribution of raf, ischemie insult also caused an increase in the level of B-raf protein in reactive astrocytes.  相似文献   
9.
10.
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