首页 | 官方网站   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   10511篇
  免费   824篇
  国内免费   31篇
医药卫生   11366篇
  2023年   58篇
  2022年   110篇
  2021年   248篇
  2020年   143篇
  2019年   247篇
  2018年   276篇
  2017年   203篇
  2016年   223篇
  2015年   239篇
  2014年   319篇
  2013年   470篇
  2012年   664篇
  2011年   723篇
  2010年   406篇
  2009年   350篇
  2008年   711篇
  2007年   698篇
  2006年   701篇
  2005年   708篇
  2004年   651篇
  2003年   604篇
  2002年   577篇
  2001年   88篇
  2000年   88篇
  1999年   112篇
  1998年   123篇
  1997年   99篇
  1996年   98篇
  1995年   95篇
  1994年   69篇
  1993年   58篇
  1992年   68篇
  1991年   62篇
  1990年   51篇
  1989年   55篇
  1988年   44篇
  1987年   51篇
  1986年   51篇
  1985年   50篇
  1984年   44篇
  1983年   60篇
  1982年   61篇
  1981年   55篇
  1980年   49篇
  1979年   36篇
  1978年   38篇
  1977年   31篇
  1976年   31篇
  1974年   30篇
  1973年   27篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Performance characteristics of pooled rabbit IgG polyclonal anti-C3d are compared with one mouse IgM and three mouse IgG monoclonal anti-C3d antibodies (MAs). IgG MA,s employed singly or in combination, failed to precipitate C3d; by contrast, IgM MA and polyclonal anti-C3d precipitated C3d. Measurements of polyclonal anti-C3d concentration by chemical means and by 125I-C3d radioimmunoassay (RIA) agreed closely. RIA values were 50% of chemical measurement values for three of the four MAs. Use of sucrose density gradient ultracentrifugation to assess MA C3d/anti-C3d molar combining ratios for soluble anti-C3d/C3d was not possible because fast-sedimenting multimeric C3d/anti-C3d complexes did not form. Dissociation and competitive binding studies indicate that (1) two MAs had substantially lower affinities than the other anti-C3d antibodies, and (2) polyclonal anti-C3d recognizes more C3d epitopes than are recognized by individual MAs. The results demonstrate antigenic complexity of C3d fragment and illustrate the difficulties of predicting individual MA performance based on prior experience with polyclonal antibodies.  相似文献   
2.
We report the identification of a new transthyretin (TTR) gene mutation and variant protein, Glu61Gly, in a 55-year-old man with progressive cardiomyopathy, mild peripheral neuropathy and bilateral carpal tunnel syndrome. A diagnosis of TTR-associated familial amyloidosis (ATTR) was considered after an endomyocardial biopsy revealed amyloid deposits in the heart of a patient who had no family history of amyloidosis and no evidence of a plasma cell dyscrasia. Serum screening for a TTR variant by isoelectric focusing (IEF) was positive and prompted further studies to identify the genetic abnormality and to characterize the amyloidogenic protein. Direct DNA sequence analysis of all four coding regions in the TTR gene demonstrated heterozygosity in exon 3. Near equal amounts of guanine (G) and adenine (A) were observed at the second base position of codon 61. The wild-type (GAG) and mutated (GGG) sequences found in codon 61 correspond to glutamic acid (Glu) and glycine (Gly) residues, amino acids which differ in mass by -72 Da. Mass spectrometric analyses of TTR immunoprecipitated from serum showed the presence of both wild-type and variant proteins. The observed mass results for the wild-type and variant proteins were consistent with the predicted values calculated from the genetic analysis data.  相似文献   
3.
Phytochemical-mediated modulation of P-glycoprotein (P-gp) and other drug transporters may give rise to many herb-drug interactions. Serial plasma concentration-time profiles of the P-gp substrate, digoxin, were used to determine whether supplementation with goldenseal or kava kava modified P-gp activity in vivo. Twenty healthy volunteers were randomly assigned to receive a standardized goldenseal (3210 mg daily) or kava kava (1227 mg daily) supplement for 14 days, followed by a 30-day washout period. Subjects were also randomized to receive rifampin (600 mg daily, 7 days) and clarithromycin (1000 mg daily, 7 days) as positive controls for P-gp induction and inhibition, respectively. Digoxin (Lanoxin, 0.5 mg) was administered p.o. before and at the end of each supplementation and control period. Serial digoxin plasma concentrations were obtained over 24 h and analyzed by chemiluminescent immunoassay. Comparisons of area under the curve (AUC)((0-3)), AUC((0-24)), C(max,) CL/F, and elimination half-life were used to assess the effects of goldenseal, kava kava, rifampin, and clarithromycin on digoxin pharmacokinetics. Rifampin produced significant reductions (p < 0.01) in AUC((0-3)), AUC((0-24)), CL/F, t(1/2), and C(max), whereas clarithromycin increased these parameters significantly (p < 0.01). With the exception of goldenseal's effect on C(max) (14% increase), no statistically significant effects on digoxin pharmacokinetics were observed following supplementation with either goldenseal or kava kava. When compared with rifampin and clarithromycin, supplementation with these specific formulations of goldenseal or kava kava did not appear to affect digoxin pharmacokinetics, suggesting that these supplements are not potent modulators of P-gp in vivo.  相似文献   
4.
5.
Single parent women   总被引:1,自引:1,他引:0  
Summary While there has been considerable interest in the problems of single parent families, no study has yet determined if the problems are due to increased risk of specific psychiatric disorders in single parents as compared to their married counterparts. Data collected as part of the National Institute of Mental Health Epidemiologic Catchment Area (ECA) Project are presented to compare the psychiatric as well as economic and social functioning of single vs. married parent women ages 18–44, based on a probability sample of members of the greater New Haven community. The major finding between groups is their relative similarity in psychiatric as well as social functioning. The major difference is economic. Single parents, both Black and White, more frequently are less educated and poorer. While many are on welfare, single compared to married female parents are more likely to be working and to report insufficient income to meet their needs. There are no appreciable differences in social contacts, use of health services or six-month prevalence rates of psychiatric disorders including major depression, alcohol or drug abuse. The data suggest that the problems faced by single parent women and their children may be a reflection of poverty and stress in families and not of psychiatric disorders or poor social relations in mothers.  相似文献   
6.
OBJECTIVE: The authors described the influence of specific medical conditions on clinical remission and response of major depression (MDD) in a clinical trial evaluating a care-management intervention among older primary-care patients. METHODS: Adults age 60 years and older were randomly selected and screened for depression. Participants were randomly assigned to Usual Care or to an Intervention with a depression care-manager offering algorithm-based care for MDD. In all, 324 adults meeting criteria for MDD were included in these analyses. Remission and response was defined by a score on the Hamilton Rating Scale for Depression <10 and by a decrease from baseline of > or =50%, respectively. Medical comorbidity was ascertained through self-report. Cognitive impairment was defined by a score <24 on the Mini-Mental State Exam (MMSE). RESULTS: In Usual Care, rates of remission were faster in persons who reported atrial fibrillation (AF) than in persons who did not report AF and slower in persons who reported chronic pulmonary disease than in persons who did not report chronic pulmonary disease; rates of response were less stable in persons with MMSE <24 than in those with MMSE > or =24. In the Intervention condition, none of the specific chronic medical conditions were significantly associated with outcomes for MDD. CONCLUSIONS: Because disease-specific findings were observed in persons who received Usual Care but not in persons who received more intensive treatment in the Intervention condition, our results suggest that the association of medical comorbidity and treatment outcomes for MDD may be determined by the intensity of treatment for depression.  相似文献   
7.
Introduction As many as one quarter of all cancer survivors report traumatic stress symptoms from cancer-related experiences. While the majority of these patients do not meet the criteria for posttraumatic stress disorder (PTSD), there is growing evidence that subsyndromal symptoms can significantly contribute to functional impairment and negative health outcomes. Treatment options for the hallmark symptoms of traumatic stress—unpleasant, intrusive thoughts and avoidant behaviors—have not been well investigated for the cancer survivorship population. Materials and methods Seven female cancer survivors with traumatic stress symptoms from cancer-related experiences and no other major psychopathology, were enrolled to receive three sessions of Neuro-Emotional Technique (NET), a brief, targeted treatment that combines traditional desensitization principles with complementary modalities. Results Psychological outcome measures (Impact of Event Scale (IES) and Subjective Units of Distress (SUD) and physiological measures (Heart Rate (HR) and Skin Conductance Level (SCL) demonstrated the following changes: 71% on IES, 88% SUD, 74% on HR, and 65% on SCL following the intervention. Statistically significant changes were observed for all four parameters, and effect size g for proportion improved were 0.50 each for IES, SUD, and HR, and 0.20 for SCL. Conclusions These cases suggest feasibility of the NET intervention for cancer-related traumatic stress and the potential for change in symptoms and physiological reactivity. Further investigation is needed to determine the specific and long-term effects of such an approach. Implications for cancer survivors Traumatic stress from cancer-related experiences might represent a constellation of symptoms that are amenable to brief, targeted interventions. This study was supported by the O.N.E. Research Foundation  相似文献   
8.
The purpose of this qualitative study was to examine the process of transformation of personal beliefs, values, feelings, and knowledge (meaning perspectives) underlying occupational change in a small group of clients with rheumatoid arthritis during home-based rehabilitation. A grounded theory approach used to collect and analyze data concurrently included: (1) a sample of five adult clients diagnosed with rheumatoid arthritis in occupational therapy, (2) data collection through 28 semi-directed interviews, and (3) data analysis using the constant comparison method. The study identified meaning perspectives of these clients with rheumatoid arthritis and explored the transformation of perspectives related to the modification of occupational performance. The study suggests that the exploration of meaning perspective transformation by clients and therapists could be a potential part of rehabilitation intervention.  相似文献   
9.
10.
The purpose of the study was to determine if optometry students who completed an externship at a military facility were influenced for or against future enlistment considerations. The responses of 62 students were evaluated over a period of 3 years using an original self-completion questionnaire. The results suggest that while the majority of students left their externship with a positive attitude toward the military practice of optometry, factors such as low salaries and lagging promotional considerations influenced most to overlook the military as a practice option. The important ramifications of the study, as well as potential threats to its validity, are discussed.  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-23

京公网安备 11010802026262号