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   21877篇
  免费   1339篇
  国内免费   166篇
耳鼻咽喉   190篇
儿科学   474篇
妇产科学   403篇
基础医学   2588篇
口腔科学   786篇
临床医学   2097篇
内科学   4796篇
皮肤病学   460篇
神经病学   1363篇
特种医学   537篇
外国民族医学   5篇
外科学   2922篇
综合类   531篇
一般理论   16篇
预防医学   1785篇
眼科学   892篇
药学   1997篇
中国医学   234篇
肿瘤学   1306篇
  2024年   39篇
  2023年   292篇
  2022年   790篇
  2021年   1238篇
  2020年   820篇
  2019年   998篇
  2018年   1182篇
  2017年   818篇
  2016年   907篇
  2015年   901篇
  2014年   1173篇
  2013年   1403篇
  2012年   1930篇
  2011年   1980篇
  2010年   1169篇
  2009年   908篇
  2008年   1315篇
  2007年   1178篇
  2006年   983篇
  2005年   819篇
  2004年   662篇
  2003年   549篇
  2002年   452篇
  2001年   64篇
  2000年   74篇
  1999年   73篇
  1998年   64篇
  1997年   52篇
  1996年   57篇
  1995年   42篇
  1994年   22篇
  1993年   37篇
  1992年   28篇
  1991年   24篇
  1990年   27篇
  1989年   27篇
  1988年   20篇
  1987年   13篇
  1986年   14篇
  1985年   15篇
  1984年   25篇
  1983年   22篇
  1982年   22篇
  1981年   16篇
  1980年   17篇
  1979年   21篇
  1978年   15篇
  1977年   13篇
  1976年   14篇
  1974年   12篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
Summary Currently there are no limitations on age of employment on private forestries in Japan. Hence, it was hypothesized that in these kind of enterprises, elderly chain saw operators, or those with long-term exposure, might be at higher risk of developing hand-arm vibration syndrome (HAVS). We consequently investigated the prevalence of HAVS in 447 chain saw workers on private forestries in Gifu Prefecture, Japan, with particular reference to age and exposure period. Of this population, 43 (9.6%) had signs and symptoms of vibration-induced white finger (VWF), and among these workers the severity of finger blanching was significantly correlated (P < 0.01) with the exposure period. Classification of all subjects by exposure period showed that workers with 30 years' exposure had higher prevalences of VWF (20.9%) and numbness of the hands (25.4%) compared to other groups. Significant differences (P < 0.01) were found between the functional capacities of workers with VWF and those of control subjects. We concluded that (a) the elderly chain saw operators and those with longer exposure should be moved to other jobs with a lower or no risk of exposure to vibration, and (b) the results of screening tests, even without cold water immersion (which we did not employ, in order to protect workers' hands), could be helpful for the identification of workers with VWF.  相似文献   
52.
To study optimal conditions of preparation of saphenous veins as coronary artery bypass grafts, segments of saphenous veins were obtained from 29 consecutive patients undergoing coronary artery bypass grafting. The saphenous vein segments were divided into three groups. In Group I, 10 saphenous vein segments were harvested using a "no-touch" technique without any other preparation aids. In Group II, 10 saphenous vein segments were removed while distended at 70-120 mm Hg with a balanced pH electrolyte solution at 37 degrees C. In Group III, consisting of 10 saphenous vein segments, nitroglycerin (1 microgram/ml) was added to the distending solution used in Group II. Samples of saphenous vein were assessed in a blind study using light and scanning electron microscopy to estimate endothelial cell preservation by the three harvest techniques. Saphenous veins receiving only a no-touch dissection technique without distention solution (Group I) revealed significantly better endothelial preservation (P less than 0.005). The administration of distention solution alone, or with nitroglycerin, to saphenous veins in situ using our operative technique during harvest does not appear to protect endothelial-integrity and may be harmful.  相似文献   
53.
In order to determine whether the enhanced reepithelialization of second-degree burns treated with octylcyanoacrylate (OCA) was due to its occlusive nature we compared reepithelialization (REP) and infection rates of second degree burns treated with OCA and polyurethane film (Tegaderm) in swine. Forty-four standardized partial thickness burns were created by applying an aluminum bar preheated to 80 degrees C to the backs of pigs for 20 s and randomly treated with OCA or Tegaderm. Full thickness biopsies were taken at 7, 10 and 14 days for blinded histopathological evaluation of rates of infection and reepithelialization. T-tests and chi(2) tests were used for group comparisons. There were no between group difference in the rates of reepithelialization and infection. All wounds were reepithelialized by day 14 and there were no infections in either group. We conclude that treatment of partial thickness burns with OCA spray or Tegaderm results in similar rates of reepithelialization and infection, suggesting that the beneficial effects of OCA on reepithelialization are due to its occlusive nature.  相似文献   
54.
A New Personal Surgical Procedure for Breast Reduction and Lifting   总被引:1,自引:0,他引:1  
A series of 40 patients operated from 1995 through 1997 is reviewed. The women ranged in age from 18 to 40 and were seen in either a university- or a private-hospital setting. Thirty-eight of the patients underwent reduction mammaplasty, which was performed using an inferior pedicle technique with a straight-line incision; two patients underwent mastopexy only. The reduction procedure depends on the formation of a cap from medial, lateral, and superior flaps. Following resection of breast tissue the cap is joined to a cone—the nipple–areola complex carried on a subcutaneous inferior pedicle. The cone is fixed to the chest wall with simple vertical stitches, minimizing the recurrence of ptosis. This technique is safe and versatile, avoids a submammary scar, and offers an aesthetic and long-lasting result.  相似文献   
55.
Draize rabbit eye test scores, as modified maximum average score (MMAS), for 68 pure bulk liquids were adjusted by the liquid-saturated vapor pressure P. These 68 adjusted scores, as log (MMAS/P), were shown to be completely equivalent to eye irritation thresholds (EIT), expressed as log (1/EIT), for 23 compounds in humans. Thus, for the first time the Draize eye test in rabbits for pure bulk liquids is shown to be perfectly compatible with eye irritation thresholds in humans. The total data set for 91 compounds was analyzed by the general solvation equation of Abraham. Values of log (MMAS/P) or log (1/EIT) could be fitted to a five-parameter equation with R2 = 0.936, SD = 0.433, AD = 0.000, and AAD = 0.340 over a range of 9.6 log units. When divided into a training set of 45 compounds, the corresponding equation could be used to predict the remaining 46 compounds in a test set with AD = -0.037 and AAD = 0.345 log units. Thus, the 91-compound equation can now be used to predict further EIT values to around 0.4 log units. It is suggested that the mechanism of action in the Draize test and in the human EIT involves passive transfer of the compound to a biophase that is quite polar, is a strong hydrogen bond base, a moderate hydrogen bond acid, and quite hydrophobic. The biophase does not resemble water or plasma, but resembles an organic solvent such as N-methylformamide.  相似文献   
56.
57.
1 BACKGROUNDTheincidenceofCPis 0 .7per 1 0 0 0livebirths[1 ] .Becausecerebralpalsyinfluencesthewaychildrendevelop,itoftenresultsindevelop mentaldisability .Today ,more peoplehavecerebralpalsythananyotherdevelopmentaldis ability ,includingDownsyndrome,epilepsy ,andautism .Accordingtoasurveyconductedin1 986,2 .6%ofthepopulationofPakistaniaredisabled (includingbothphysicalandmentaldis abilities) .Childrenbetween 0~1 4 yearsinageconstitute 40 %ofthedisabled populationinPakistan .Routineme…  相似文献   
58.
PURPOSE: To describe a randomized trial of a cognitive behavioral intervention on reducing symptom severity among patients diagnosed with solid tumors and undergoing a first course of chemotherapy and to determine whether the intervention had an additive or interactive effect on symptom severity in the presence of supportive care medications. PATIENTS AND METHODS: Patients (N = 237) were accrued from comprehensive and community cancer centers, interviewed, and randomly assigned to either the experimental intervention (n = 118) or conventional care (n = 119). A symptom severity index, based on summed severity scores across 15 symptoms, was the primary outcome. Each patient's site of cancer, stage at diagnosis, chemotherapy protocols, and use of supportive medications were learned from medical records. RESULTS: Groups were equivalent at baseline, and attrition by characteristics by group was not different. The proportion of patients not receiving chemotherapy at 10 and 20 weeks did not differ by group. At the 10- and 20-week observations, there was a significant interaction between the experimental group and baseline symptom severity. Patients in the experimental group who entered the trial with higher symptom severity reported significantly lower severity at 10 and 20 weeks. Controlling for chemotherapy treatment status at follow-up and supportive care medications did not alter the effect of the experimental intervention. CONCLUSION: Compared with conventional care alone, the experimental intervention was effective among patients who entered the trial with higher levels of symptom severity. Age, sex, site or stage of cancer, and supportive medications did not modify the effect of this cognitive behavioral intervention on symptom severity.  相似文献   
59.
We have previously reported that XK469 (2-[4-(7-chloro-2-quinoxalinyloxyphenoxy]-propionic acid) enhances topo IIalpha expression in WSU-WM cells in vitro [E. Mensah-Osman et al., Mol. Cancer Ther., 1: 1321-1326, 2002]. To test the hypothesis that XK469-induced expression of topo IIalpha sensitizes WSU-WM cells to the topo IIalpha inhibitor etoposide (VP-16), we investigated the antitumor effects of XK469 and VP-16 in vivo, using the WSU-WM SCID xenograft model. Individual dosages of XK469 at 20-60 mg/kg/injection i.v. for a maximum-tolerated dose of 240 mg/kg were achievable in SCID mice. Simultaneous administration of a subtherapeutic dose of XK469 (20 mg/kg) and VP-16 at its maximum-tolerated dose of 15 mg/kg proved to be highly toxic and lethal. However, daily sequential treatment of XK469 given i.v. via tail vein at 20 mg/kg for a total of 120 mg/kg, followed 7 h later by VP-16 i.p. at 15 mg/kg for a total of 90 mg/kg, had no significant toxicity in SCID mice. The sequential treatment was associated with enhanced antitumor activity. Tumor growth inhibition T/C, tumor growth delay T-C, and log(10) kill for XK469 alone were 61%, 3 days and 0.46; VP-16 alone 6%, 12 days and 1.83, respectively; whereas the sequential administration of both agents gave a T/C value of 0%, T-C value of 23 days and a log(10) kill of 3.5. On the basis of these animal results, we conclude that the sequential treatment of WSU-WM tumors with XK469 and VP-16 was highly active. The study supports our in vitro observation that XK469 potentiates VP-16 activity. The sequential use of both agents resulted in clinically significant antitumor activity in the WM model.  相似文献   
60.
Objective. The objective of this study was to determine whether the size of the pyloric mass is one of the factors in the surgeon's ability to palpate the pyloric “olive”. Materials and methods. The ultrasonographic images and medical records of 60 infants with surgically confirmed hypertrophic pyloric stenosis (HPS) were reviewed. The pyloric diameter (PD) and pyloric length (PL) were measured and the pyloric volume (PV) was calculated using the equation PV = 1/4π× (PD)2× PL. Based on the pediatric surgeon's physical examination the infants were divided into two groups: those with and those without palpable pyloric masses. Results. Infants with a palpable pyloric mass had an average pyloric volume of 3.33 ± 1.76 mm3, which was statistically larger than those whose hypertrophied pylorus could not be palpated (average volume 2.59 ± 2.07 mm3, P < 0.01). There was no statistically significant age difference between the two groups. Conclusion. Clinical skill of the examiner and other clinical aspects (patient cooperation, etc.) determine palpability of the pylorus in HPS. The size of the hypertrophied pylorus is also an important factor affecting the clinican's ability to palpate the pyloric mass. Received: 29 December 1995 Accepted: 7 June 1996  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