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   4599篇
  免费   252篇
  国内免费   84篇
耳鼻咽喉   11篇
儿科学   210篇
妇产科学   54篇
基础医学   454篇
口腔科学   177篇
临床医学   580篇
内科学   805篇
皮肤病学   256篇
神经病学   284篇
特种医学   404篇
外科学   529篇
综合类   94篇
一般理论   2篇
预防医学   369篇
眼科学   271篇
药学   145篇
肿瘤学   290篇
  2021年   33篇
  2019年   38篇
  2018年   33篇
  2017年   35篇
  2016年   48篇
  2015年   45篇
  2014年   64篇
  2013年   103篇
  2012年   122篇
  2011年   134篇
  2010年   108篇
  2009年   98篇
  2008年   166篇
  2007年   203篇
  2006年   162篇
  2005年   163篇
  2004年   159篇
  2003年   128篇
  2002年   114篇
  2001年   107篇
  2000年   121篇
  1999年   113篇
  1998年   138篇
  1997年   117篇
  1996年   141篇
  1995年   113篇
  1994年   111篇
  1993年   105篇
  1992年   98篇
  1991年   124篇
  1990年   127篇
  1989年   131篇
  1988年   144篇
  1987年   131篇
  1986年   123篇
  1985年   110篇
  1984年   80篇
  1983年   67篇
  1982年   50篇
  1981年   57篇
  1980年   46篇
  1979年   54篇
  1978年   66篇
  1977年   52篇
  1976年   47篇
  1975年   34篇
  1973年   40篇
  1972年   35篇
  1970年   37篇
  1969年   31篇
排序方式: 共有4935条查询结果,搜索用时 15 毫秒
11.
We examined the records of 105 patients with advanced ovarian cancer who had been treated with cisplatin combination chemotherapy followed by abdominopelvic radiotherapy. The purpose was to define the morbidity of this approach, and identify those factors predictive of toxicity. Acute toxicity resulting in delay or failure to complete treatment was most commonly due to myelosuppression. Nine of 105 patients (8.6%) required surgery for bowel obstruction that was not due to recurrent disease, 3 had an episode of bowel obstruction that settled conservatively, and a further 5 underwent surgery for obstruction due to recurrent tumor. The presence of both a dose of abdominopelvic radiotherapy over 2250 cGy, as well as a second-look laparotomy prior to radiotherapy, was associated with an increased risk of serious bowel complications. The increased frequency of late bowel morbidity seen in the combined modality group is likely explained by the presence of these two factors, rather than the exposure to chemotherapeutic agents per se. These observations are supported by the published literature.  相似文献   
12.
Different morphologic and density classes of sickle cells (SS) may play distinct roles in the generation of vasoocclusion, explaining the complexity of this phenomena. The densest SS red blood cells (RBCs) (SS4) can induce vasoocculsion in ex vivo microcirculatory preparations as well as in an intact animal model. Previous studies of the interaction of SS deformable discocytes with endothelial monolayers or the rat ex vivo mesocecum preparation have shown adhesion that is desmopressin (dDAVP)-stimulated, von Willebrand factor (vWF)-mediated, and limited to the small venules. However, in vivo adhesion of SS RBCs to the endothelium has neither been demonstrated nor characterized; and, in particular, the relation of adhesion to vasoocclusion is unknown. Using an intact animal model that involves injecting saline-washed, density-defined SS RBCs into the femoral artery of a rat, we find that: (1) Quantitative studies of RBCs retained in the rat thigh using 99mTc-labeled RBCs and gamma camera imaging showed that dDAVP induces a threefold increase in retention of normal (AA) cells and deformable SS discocytes (SS2). (2) electron microscopy and Microfil injection show that the retention of SS2 cells is due to adhesion to the vascular endothelium with no evidence of obstruction. (3) H-1 magnetic resonance imaging showed that retention of SS4 cells induced a dose-dependent increase in tissue edema (presumable secondary to tissue hypoxia), while retention of AA or SS2 cells produced no change. We conclude that endothelial adhesion of deformable SS discocytes can be demonstrated in an in vivo animal model, that this adhesion is enhanced by dDAVP (presumably related to, but not necessarily limited to the release of vWF), and that this phenomenon per se does not lead to vasoocclusion. Nevertheless, adhesion of deformable SS discocytes may have consequences. We hypothesize that adhesion of SS discocytes could narrow the lumen of postcapillary venules and facilitate secondary trapping of SS4 cells and lead to subsequent vasoocclusion.  相似文献   
13.
This paper examines the sensitivity and specificity of two ELISA assays for IgM antibodies to Mycobacterium leprae, one employing natural phenolic glycolipid and the other employing a synthetic disaccharide glycoconjugate as antigen. Estimates of sensitivity and specificity are derived, based on a panel of sera from leprosy cases in Malawi and various non-leprosy controls from the UK. Though both assays were able to identify a high proportion of multibacillary patients, neither was able to detect a high proportion of paucibacillary patients without considerable loss of specificity. The implications of the inverse relationship between sensitivity and specificity are discussed with reference to the predictive value of such tests in such areas as Malawi, where the large majority of cases are paucibacillary.  相似文献   
14.
15.
16.
In 1998, the New York City Department of Health and the Mayor’s Office of Emergency Management began monitoring the volume of ambulance dispatch calls as a surveillance tool for biologic terrorism. We adapted statistical techniques designed to measure excess influenza mortality and applied them to outbreak detection using ambulance dispatch data. Since 1999, we have been performing serial daily regressions to determine the alarm threshold for the current day. In this article, we evaluate this approach by simulating a series of 2,200 daily regressions. In the influenza detection implementation of this model, there were 71 (3.2%) alarms at the 99% level. Of these alarms, 64 (90%) occurred shortly before or during a period of peak influenza in each of six influenza seasons. In the bioterrorism detection implementation of this methodology, after accounting for current influenza activity, there were 24 (1.1%) alarms at the 99% level. Two occurred during a large snowstorm, 1 is unexplained, and 21 occurred shortly before or during a period of peak influenza activity in each of six influenza seasons. Our findings suggest that this surveillance system is sensitive to communitywide respiratory outbreaks with relatively few false alarms. More work needs to be done to evaluate the sensitivity of this approach for detecting nonrespiratory illness and more localized outbreaks.  相似文献   
17.
18.
Hand wrist cumulative trauma disorders in industry   总被引:5,自引:0,他引:5  
A total of 574 active workers from six different industrial sites were categorised into four force repetitive exposure groups. Workers in low force-low repetitive jobs served as an internal comparison population for the three other groups. Videotapes and surface electromyography were used to estimate hand force and repetitiveness. The presence of cumulative trauma disorders (CTD) was determined by structured interview and standardised non-invasive physical examination. Only workers who had been working on the study jobs for at least one year at the time of evaluation were eligible for selection. Categorisation of jobs and identification of CTDs were carried out independently by investigators who were appropriately blinded to exposure and outcome. The analysis of associations between CTDs and exposure categories were performed using Mantel-Haenszel plant adjusted odds ratios and unconditional multiple logistic regression. Significant positive associations were observed between hand wrist CTDs and high force-high repetitive jobs. These associations were independent of age, sex, years on the specific job, and plant.  相似文献   
19.
BACKGROUND: Knowledge of the prevalence of peripheral arterial disease (PAD) in patients with chronic renal failure (CRF) is limited because of a lack of uniformity in disease definition and recognition. Furthermore, little is known of the prevalence of medial arterial calcification (MAC) in patients with CRF. Our goal is to study the prevalence of PAD and MAC defined by ankle brachial index (ABI) or toe brachial index (TBI) measurements in a Finnish population of patients with CRF consisting of predialysis and dialysis patients, as well as renal transplant recipients. METHODS: We examined 136 patients with CRF and 59 control subjects. Fifty-nine of the patients with CRF had moderate to severe predialysis CRF, 36 patients were on dialysis treatment, and 41 were renal transplant recipients. Mean age of patients was 51.9 +/- 11.5 years, and 39 patients (29%) had diabetes. ABI and TBI were measured by means of photoplethysmography. The definition of PAD required an ABI value of 0.90 or less, a TBI value of 0.60 or less, or a previous positive lower-extremity angiogram result. ABI values of 1.3 or greater or incompressible arteries at ankle level indicated MAC. The presence of claudication was determined by an interview. RESULTS: Prevalences of PAD on this study were 22.0% in patients with predialysis CRF, 30.6% in patients on dialysis treatment, 14.6% in renal transplant recipients, and 1.7% in the control group (P = 0.001). Prevalences of MAC were 23.7%, 41.7%, 23.1%, and 3.4% (P < 0.001), respectively. Only 9 patients had claudication, and 6 of those patients had PAD. CONCLUSION: Both asymptomatic PAD and MAC are common in patients with CRF. Therefore, we recommend the use of both ABI and TBI measurements in the evaluation of PAD in patients with CRF.  相似文献   
20.
This article briefly reviews the tactical integrationist's perspective in the work with multiple personality disorder patients. Its foundation is a cognitively based treatment paradigm geared toward controlled abreactions with cognitive restructuring throughout therapy. It is a suppression-dilution-of-affect model that focuses on the achievement of control and mastery for patient and therapist alike.  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