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   1417篇
  免费   118篇
耳鼻咽喉   8篇
儿科学   77篇
妇产科学   90篇
基础医学   147篇
口腔科学   14篇
临床医学   174篇
内科学   224篇
皮肤病学   32篇
神经病学   190篇
特种医学   30篇
外科学   129篇
综合类   11篇
一般理论   4篇
预防医学   185篇
眼科学   8篇
药学   101篇
肿瘤学   111篇
  2024年   3篇
  2023年   9篇
  2022年   15篇
  2021年   19篇
  2020年   34篇
  2019年   29篇
  2018年   42篇
  2017年   29篇
  2016年   47篇
  2015年   36篇
  2014年   68篇
  2013年   80篇
  2012年   105篇
  2011年   102篇
  2010年   58篇
  2009年   63篇
  2008年   96篇
  2007年   95篇
  2006年   90篇
  2005年   96篇
  2004年   74篇
  2003年   70篇
  2002年   61篇
  2001年   14篇
  2000年   9篇
  1999年   9篇
  1998年   20篇
  1997年   17篇
  1996年   10篇
  1995年   14篇
  1994年   6篇
  1993年   6篇
  1992年   8篇
  1991年   14篇
  1990年   5篇
  1989年   3篇
  1988年   3篇
  1986年   7篇
  1985年   8篇
  1984年   4篇
  1983年   3篇
  1982年   11篇
  1980年   7篇
  1978年   3篇
  1975年   3篇
  1973年   5篇
  1971年   5篇
  1970年   2篇
  1969年   4篇
  1960年   2篇
排序方式: 共有1535条查询结果,搜索用时 15 毫秒
71.
OBJECTIVE: To evaluate the impact of patient notification of impending formulary changes on formulary adherence. METHODS: This pilot program in a large, Midwest-based health insurer utilized a randomized controlled trial research design. A list of 30 chronic-use medications that were to change formulary status were selected for the pilot. A review of adjudicated pharmacy claims records was performed to identify patients receiving one or more of the formulary change medications on the list. Members of 112 individual health plans of this large health insurer, all of whom were subject to the same drug formulary, were randomized to either the intervention (letter) or control arm. Patients in the intervention arm were sent a targeted communication that described the patient.s formulary change medication(s) and provided therapeutic option(s) for the formulary change medication(s). Pharmacy claims for patients in both arms were examined at 110 days after the date of the mailing to determine if there was a switch to a formulary alternative. Multivariate regression modeling was performed to adjust for baseline differences between the arms. RESULTS: A total of 7,247 unique formulary change medication regimens were identified (3,817 in the control arm and 3,430 in the letter arm) for 6,518 subjects (3,387 in the control arm and 3,131 in the letter arm). A higher proportion of formulary change medication regimens in the intervention arm were switched to a formulary alternative compared with the control arm (19.2% vs. 12.0%, P<0.001). After adjustment for baseline differences, regression modeling indicated that subjects in the intervention arm were 1.33 times more likely to switch to a formulary alternative (P<0.001). CONCLUSION: A letter-based, formulary change notification program is a pragmatic and effective strategy to increase drug formulary adherence. Such a program does not restrict access to medications but, rather, provides education and personalized information that may allow patients to participate more actively in their pharmacotherapy decision making.  相似文献   
72.
OBJECTIVE: This study examined the relation of occupational solvent exposure to menopausal and other symptoms in midlife women. METHODS: We conducted a cross-sectional study of 480 Chinese and 494 white women, aged 40-55 years, in Northern California. Levels of exposure to organic solvents (none, low, medium, or high) were assigned to each current job using a job-exposure matrix. RESULTS: A lower proportion of women with low occupational organic solvent exposure reported hot flashes or night sweats than working women with no solvent exposure (adjusted prevalence odds ratio [APOR] = 0.48, 95% confidence interval [CI] = 0.19-1.21). A greater proportion of women with high solvent exposure reported forgetfulness than women with no exposure (APOR = 2.51, 95% CI = 1.12-5.63). CONCLUSIONS: Some symptom reporting in midlife women was related to their occupational organic solvent exposure.  相似文献   
73.
Background:This study investigates the expression patterns in human adipose tissue, and identifies genes that may be involved in the abnormal energy homeostasis. Methods: Subjects were prospectively recruited from morbidly obese patients undergoing bariatric surgery and from non-obese organ donors. Extensive clinical data and visceral fat specimens were obtained from each subject at the time of surgery. A group of 50 obese patients and 9 non-obese controls were selected for further study. Two custom two-color cDNA microarrays were produced with 40,173 human individual cDNA clones. Microarray experiments were performed for each sample, and a selected group of gene expression values were confirmed with real-time RT-PCR. Results: A comparison of gene expression profiles from obese and non-obese patients identified 1,208 genes with statistically significant differential expression between the 2 groups. Most prominent among these genes are multiple glycolysis enzyme encoding genes; others are involved in oxysterol biosynthesis and signaling, or are ATP-binding transporters and solute carriers. Conclusion: Differential gene expression in the adipose tissue of morbidly obese patients includes genes related to lipid and glucose metabolism, membrane transport, and genes promoting the cell cycle. These findings are a first step toward clarifying the molecular pathogenesis of obesity and identifying potential targets for therapeutic intervention.  相似文献   
74.
Pectus excavatum is a chest wall deformity that commonly warrants pediatric surgical correction for cosmesis or respiratory impairment via sternotomy. The repair typically consists of sternal wedge osteotomy and subsequent placement of a Steinman pin across the sternum with fixation to the ribs bilaterally. Coronary artery bypass grafting (CABG) after surgical repair of the sternum with a metal implant poses an intriguing surgical challenge. Literature review reveals only one such previously described case. We present a case of coronary revascularization in an adult who previously underwent pectus excavatum repair with ligation of the internal mammary arteries. Our coronary revascularization was accessed through a resternotomy after surgical removal of the metal implant previously placed during the pectus excavatum repair. Autologous greater saphenous vein was used as a conduit for bypass. The patient did well postoperatively and was discharged on postoperative day 4. The pectus repair remained intact even after the median sternotomy was performed. This was confirmed at the 1-year follow-up for the patient. Resternotomy after pectus excavatum repair with a prosthetic implant poses a challenge to cardiothoracic surgeons. Many such repairs have been described in the pediatric population. As our society ages and coronary artery disease becomes more prevalent, this unique situation may be more commonly encountered. We present an approach to coronary artery bypass grafting via median resternotomy after pectus excavatum repair.  相似文献   
75.
Maintenance of a reduced body weight is accompanied by decreased energy expenditure that is due largely to increased skeletal muscle work efficiency. In addition, decreased sympathetic nervous system tone and circulating concentrations of leptin, thyroxine, and triiodothyronine act coordinately to favor weight regain. These "weight-reduced" phenotypes are similar to those of leptin-deficient humans and rodents. We examined metabolic, autonomic, and neuroendocrine phenotypes in 10 inpatient subjects (5 males, 5 females [3 never-obese, 7 obese]) under 3 sets of experimental conditions: (a) maintaining usual weight by ingesting a liquid formula diet; (b) maintaining a 10% reduced weight by ingesting a liquid formula diet; and (c) receiving twice-daily subcutaneous doses of leptin sufficient to restore 8 am circulating leptin concentrations to pre-weight-loss levels and remaining on the same liquid formula diet required to maintain a 10% reduced weight. During leptin administration, energy expenditure, skeletal muscle work efficiency, sympathetic nervous system tone, and circulating concentrations of thyroxine and triiodothyronine returned to pre-weight-loss levels. These responses suggest that the weight-reduced state may be regarded as a condition of relative leptin insufficiency. Prevention of weight regain might be achievable by strategies relevant to reversing this leptin-insufficient state.  相似文献   
76.
The maximum lifespan of naked mole-rats (NMRs; Heterocephalus glaber) is greater than that of any other rodent. These hystricognaths survive in captivity >28 years, eight-times longer than similar-sized mice. The present study tested if NMRs possess superior antioxidant defenses compared to mice and if age-related interspecies changes in antioxidants were evident. Activities of Cu/Zn superoxide dismutase (Cu/Zn, SOD), Mn SOD, catalase and cellular glutathione peroxidase (cGPx) were measured in livers of physiologically equivalent age-matched NMRs (30, 75 and 130 months) and CB6F1 mice (4, 12 and 18 months). In mice, Mn SOD activity increased with age, while the activity of catalase and cGPx declined. None of the antioxidants changed with age in mole-rats. cGPx activity of NMRs was 70-times lower (p < 0.0001) than in mice, and resembled that of cGPx knock-out animals. NMRs may partially compensate for the lower cGPx when compared to mice, by having moderately higher activities of the other antioxidants. It is nonetheless unlikely that antioxidant defenses are responsible for the eight-fold longevity difference between these two species. Maintenance of constant antioxidant defenses with age in NMRs concurs with previous physiological data, suggesting delayed aging in this species.  相似文献   
77.
INTRODUCTION: Metal baseball bats produce higher ball exit velocity (BEV) than wood bats, increasing the risk of impact injuries to infield players. In this paper, maximum BEV from a wood and a metal bat were determined using the finite element method. METHODS: Three-dimensional (3-D) bat kinematics at the instant of impact were determined from high-speed videography (N = 17 high-performance batters). A linear viscoelastic constitutive model was developed for stiffer and softer types of baseballs. The risk of impact injury was determined using available movement time data for adult pitchers; the data indicate that 0.400 s is required to evade a batted ball. RESULTS: The highest BEV (61.5 m.s(-1)) was obtained from the metal bat and the stiffer ball model, equating to 0.282 s of available movement time. For five impacts along the long axis of each bat, the "best case scenario" resulted from the wood bat and the softer ball (46.0 m.s(-1), 0.377 s). CONCLUSIONS: The performance difference between the bats was attributed to the preimpact linear velocity of the bat impact point and to differences in orientation on the horizontal plane. Reducing the swing moment of the baseball bat, and the shear and relaxation modulii of the baseball, increased the available movement time.  相似文献   
78.
79.
Baseball has one of the highest impact injury rates of all sports. These injuries are primarily attributed to impact by a ball after it has been hit, pitched or thrown. This paper will review the incidence and causal factors for impact injuries in baseball. Attention is given to the design and material properties of bats, in light of evidence suggesting balls hit into the infield from metal bats can reach velocities potentially lethal to defensive players. The distribution of bat mass along the long axis of the implement appears a major factor in the greater performance potential of metal bats over wooden bats of equal length and mass. The dynamic behaviour of baseballs has also been implicated in the severity of head and chest injuries experienced by players. Balls of greatly reduced stiffness have been introduced for junior play, but debate still remains over their performance and impact characteristics. The behaviour of the ball during high-speed impact with the bat has been the subject of relatively limited research, and the effect of manipulating baseball material properties to decrease batted-ball velocity is unclear. The value of batting helmets is evident in the observed reduction of head injuries in baseball, but the use of protective vests to decrease the incidence and severity of cardio-thoracic trauma appears to be contraindicated.  相似文献   
80.
Sleep problems across the life cycle in women   总被引:3,自引:0,他引:3  
Opinion statement Across the life cycle of women, the quality and quantity of sleep can be markedly impacted by internal (eg, hormonal changes and vasomotor symptoms) and external (financial and child-care responsibilities; marital issue) factors. This paper will outline some of the major phases of the life cycle in women that have been associated with sleep problems. The main messages from this paper include 1) that very little systematic, large-scale research has been performed in virtually every area reviewed; and 2) once identified, the sleep problem is generally best addressed by the standard therapeutic approach, except in the case of pregnant and lactating women in which concern for the fetus and child must be considered in the treatment decision. This paper is organized into sections that address sleep problems associated with the menstrual cycle, pregnancy, postpartum, and perimenopause. Anecdotal reports recommend treatment that addresses the specific physical discomfort experienced by the woman (eg, analgesics for premenstrual pain, pregnancy pillows for backache, and hormone replacement therapy for hot flashes). The importance of developing standard treatment recommendations is stressed because the development of chronic insomnia has been linked to precipitating events. In addition, primary sleep disorders (eg, sleep apnea or restless legs syndrome) have been shown to increase during pregnancy and menopause, but treatment recommendations may be contraindicated or are not specific for women.  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