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   2365篇
  免费   124篇
  国内免费   10篇
耳鼻咽喉   18篇
儿科学   160篇
妇产科学   64篇
基础医学   370篇
口腔科学   50篇
临床医学   169篇
内科学   358篇
皮肤病学   77篇
神经病学   243篇
特种医学   22篇
外国民族医学   1篇
外科学   314篇
综合类   58篇
一般理论   2篇
预防医学   146篇
眼科学   61篇
药学   172篇
中国医学   5篇
肿瘤学   209篇
  2023年   26篇
  2022年   58篇
  2021年   101篇
  2020年   45篇
  2019年   74篇
  2018年   62篇
  2017年   55篇
  2016年   75篇
  2015年   78篇
  2014年   130篇
  2013年   144篇
  2012年   211篇
  2011年   255篇
  2010年   104篇
  2009年   83篇
  2008年   143篇
  2007年   120篇
  2006年   105篇
  2005年   101篇
  2004年   93篇
  2003年   86篇
  2002年   61篇
  2001年   30篇
  2000年   37篇
  1999年   20篇
  1998年   13篇
  1997年   16篇
  1996年   10篇
  1995年   11篇
  1994年   6篇
  1993年   9篇
  1992年   15篇
  1991年   18篇
  1990年   11篇
  1989年   12篇
  1988年   7篇
  1987年   8篇
  1986年   5篇
  1985年   14篇
  1984年   3篇
  1983年   5篇
  1982年   10篇
  1981年   4篇
  1980年   2篇
  1979年   3篇
  1977年   3篇
  1974年   3篇
  1973年   2篇
  1972年   3篇
  1971年   4篇
排序方式: 共有2499条查询结果,搜索用时 0 毫秒
1.
The Effect of Cuts in Medicare Reimbursement on Hospital Mortality   总被引:1,自引:0,他引:1  
Objective. To determine if patients treated at hospitals under different levels of financial strain from the Balanced Budget Act (BBA) of 1997 had differential changes in 30-day mortality, and whether vulnerable patient populations such as the uninsured were disproportionately affected.
Data Source. Hospital discharge data from all general acute care hospitals in Pennsylvania from 1997 to 2001.
Study Design. A multivariate regression analysis was performed retrospectively on 30-day mortality rates, using hospital discharge data, hospital financial data, and death certificate information from Pennsylvania.
Data Collection. We used 370,017 hospital episodes with one of four conditions identified by the Agency for Healthcare Research and Quality as inpatient quality indicators were extracted.
Principal Findings. The average magnitude of Medicare payment reduction on overall net revenues was estimated at 1.8 percent for hospitals with low BBA impact and 3.6 percent for hospitals with a high impact in 1998, worsening to 2 and 4.8 percent, respectively, by 2001. Operating margins decreased significantly over the time period for all hospitals ( p <.05). While unadjusted mortality rates demonstrated a disproportionate rise in mortality for patients from high impact hospitals from 1997 to 2000, adjusted analyses show no consistent, significant difference in the rate of change in mortality between high-impact and low-impact hospitals ( p =.04–.94). Similarly, uninsured patients did not experience greater increases in mortality in high-impact hospitals relative to low-impact hospitals.
Conclusions. An analysis of hospitalizations in the Commonwealth of Pennsylvania did not find an adverse impact of increased financial strain from the BBA on patient mortality either among all patients or among the uninsured.  相似文献   
2.
Abstract: Between 1970 and 1990, 1,008 patients with early-stage breast cancer were treated by conservative surgery without axillary dissection followed by radiation therapy to the intact breast in the Department of Therapeutic Radiology at Yale-New Haven Hospital. The patient population, broken down by histologic subtype, was as follows: 761 patients presented with infiltrating ductal carcinoma, 70 patients with pure intraductal, 38 intraductal with focal invasion, 54 infiltrating lobular, 21 tubular, 17 medullary, 16 mucinous, and 29 with other various histologic subtypes. Patients were followed on a regular basis by the referring physicians and radiation oncologists. Diagnostic studies for distant metastases were performed as clinically indicated. Annual mammography was a routine component of the follow-up program. As of 3/96, with a median follow-up of 10.5 years, 83 patients developed an ipsilateral breast tumor recurrence, and 109 patients developed distant metastases resulting in an overall 10-year breast recurrence-free rate of 84%, and a 10-year distant metastasis-free rate of 78%. There were significant differences in clinical stage, pathological nodal involvement, and administration of systemic therapy between various histologic subtypes. As expected, those patients with histologies of low metastatic potential (such as intraductal, tubular, and mucinous) had significantly superior distant recurrence-free survival rates. With respect to breast relapse rates, there were no statistically significant differences in the 5- and 10-year breast recurrence-free rates between any of the histologic subtypes. Patients with intraductal carcinoma with or without focal invasion had similar breast relapse rates as those with other histologic subtypes. Patients with lobular carcinoma in situ as a histologic component also had a similar overall breast relapse-free recurrence rate. In conclusion, long-term follow-up of conservatively treated breast cancer patients demonstrates no significant differences in ipsilateral breast tumor recurrence rates between various histologic subtypes. There are no histologies which had a statistically significantly higher breast-relapse rate than infiltrating ductal carcinomas and therefore no primary histologic subtype represents a relative contraindication to breast conservation therapy.  相似文献   
3.
Germline mutations of the Apc tumor suppressor gene result in increased risk for gastrointestinal carcinogenesis. The Apc1638N [+/-] mouse exhibits accelerated gastrointestinal carcinogenesis that is modifiable by select pharmacological and dietary agents. Experiments in the present study were conducted on a subculturable epithelial 1638NCOL cell line established from histologically normal colon of Apc1638N [+/-] mouse to examine the effects of selected chemopreventive agents that differ in their mechanism of action. Extent of growth arrest, number of cell population doublings, cell cycle progression and aneuploid G0/G1: S + G2/M ratio represented the quantitative endpoints for the susceptibility and efficacy of chemopreventive agents. Treatment of exponentially growing 1638NCOL cells with maximum cytostatic dose of 9cisRA, DFMO or SUL (100 microM) produced a 60-70% growth arrest, that with TAM and AMF (10 microM) produced a 20-40% growth arrest, while that with OLT (100 microM) produced a 25% growth arrest. This response was associated with corresponding decrease in the number of cell population doubling. 9cisRA, SUL or AMF increased the aneuploid G0/G1: S + G2/M ratio by inducing G1 checkpoint arrest, while DFMO, TAM and OLT decreased the ratio by inducing G2 checkpoint arrest. Thus, cell cycle phase-dependent susceptibility of the Apc [+/-] 1638NCOL cell line to mechanistically distinct chemopreventive agents validates a novel colon epithelial cell culture model for mechanistic, preventive or therapeutic studies on Apc regulated colon carcinogenesis.  相似文献   
4.
ABSTRACT

Introduction

Biomarkers may help influence long-term outcomes of psoriatic disease by improving the objective assessment of the presence and severity of psoriatic arthritis (PsA) and by guiding treatment selection. However, there are no validated biomarkers for PsA.  相似文献   
5.
Three fowl adenovirus 4 (FAV4) isolates from chicken and one from quail, all from Tamil Nadu, India were analyzed. The L1 loop variable region of hexon gene of these isolates was amplified by PCR and sequenced. The nucleotide sequences (442 bp) and deduced amino acid sequences of the four isolates were compared with those of other isolates of FAV4. The nucleotide sequences of the four isolates had a 98% homology with other Indian isolates and a 96% homology with Belgian and Russian isolates. The amino acid sequences of the four Indian isolates had a more than 98% homology with other Indian isolates and a more than 92% homology with Belgian and Russian isolates. Hence, the variable of L1 loop region of hexon gene was found to be highly homologous in all the FAV4 isolates tested both at nucleotide and amino acid level.  相似文献   
6.
Haemophilus influenzae type b (Hib) is responsible for significant morbidity and mortality worldwide, particularly in children under 5 years of age. In countries where the Hib conjugate vaccine is not routinely used, Hib is a leading cause of childhood pneumonia and meningitis. Routine use of the Hib conjugate vaccines has resulted in a remarkable decline in Hib disease in developed and developing countries. However, Hib conjugate vaccines are not routinely available in most developing countries, many of which have high burdens of Hib disease. This review outlines the pathogenesis and epidemiology of Hib disease, and the various options for prevention.  相似文献   
7.
8.
Abstract   β-thalassemia is the most-common genetic disorder of hemoglobin synthesis in Malaysia, and about 4.5% of the population are heterozygous carriers of the disorder. Prenatal diagnosis was performed for 96 couples using the Amplification Refractory Mutation System and Gap-Polymerase Chain Reaction. We identified 17 β-globin defects-initiation codon for translation (T-G), -29 (A-G), -28 (A-G), CAP +1 (A-C), CD 8/9 (+G), CD 15 (G-A), CD 17 (A-T), CD 19 (A-G), Hb E (G-A), IVS1-1 (G-T), IVS1-5 (G-C), CD 41/42 (-CTTT), CD 71–72 (+A), IVS2-654 (CT), poly A(A-G), 100-kb Gγ(Aγδβ)° and 45-kb Filipino deletions. The 192 β-alleles studied comprised Chinese (151 patients), Malay (21), Orang Asli from East Malaysia (15), Filipino (1), Indian (1), Indonesian Chinese (2), and Thai (1). In the Chinese, 2 β-globin defects at CD 41/42 and IVS2-654 were responsible for 74% of β-thalassemia. β-mutations at CD 19, IVS1-1 (G-T), IVS1-5, poly A, and hemoglobin E caused 76% of the hemoglobin disorders in the Malays. The Filipino 45-kb deletion caused 73.3% of bthalassemia in the Orang Asli. Using genomic sequencing, the rare Chinese β-mutation at CD 43 (G-T) was confirmed in 2 Chinese, and the Mediterranean mutation IVS1-1 (G-A) was observed in a Malay β-thalassemia carrier. The β-globin mutations confirmed in this prenatal diagnosis study were heterogenous and 65 (68%) couples showed a different globin defect from each other. The use of specific molecular protocols has allowed rapid and successful prenatal diagnosis of β-thalassemia in Malaysia.  相似文献   
9.
10.
Human herpesvirus 6 (HHV-6) prototype isolate GS is a newly identified lymphotropic herpesvirus and several subsequent herpes isolates were recognized as HHV-6 by their hybridization to a HHV-6(GS) DNA probe pZVH14. DNA restriction analysis and in vitro tropism studies show that HHV-6 isolates can be divided into two groups, designated group A and group B. Antigenic relationships among 15 HHV-6 isolates belonging to these two groups were examined using rabbit antibodies against HHV-6(GS) infected cells, 11 monoclonal antibodies against three glycoproteins and four non-glycoproteins of HHV-6(GS), and sera from 136 healthy adults. More than 20 polypeptides from all these isolates were immunoprecipitated by rabbit polyclonal antibodies against HHV-6(GS) infected cells. Reactivities of monoclonal antibodies segregated these isolates into the same two groups. Group A contains HHV-6(GS), HHV-6(U1102) from a Ugandan acquired immunodeficiency syndrome (AIDS) patient, and nine other HHV-6 isolates from various disorders. HHV-6(Z-29) from a Zairian AIDS patient, HHV-6(SF) isolated from the saliva of a human immunodeficiency virus (HIV)-infected individual, HHV-6(OK) from a child with exanthem subitum, and HHV-6(DC) from a leukopenia patient are in group B. Eighty-one percent of the sera showed similar antibody titer in immunofluorescence assay with group A HHV-6(GS) and group B HHV-6(Z-29) infected cells and 19% of the sera showed two- to four-fold antibody titer differences. The mobilities of many of the polypeptides immunoprecipitated from group A HHV-6(GS) and group B HHV-6(Z-29) infected cells were different and sera showed differences in the quantities and nature of polypeptides immunoprecipitated.(ABSTRACT TRUNCATED AT 250 WORDS)  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