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   1074篇
  免费   39篇
耳鼻咽喉   22篇
儿科学   39篇
妇产科学   32篇
基础医学   105篇
口腔科学   27篇
临床医学   47篇
内科学   237篇
皮肤病学   16篇
神经病学   49篇
特种医学   86篇
外科学   197篇
综合类   17篇
预防医学   57篇
眼科学   43篇
药学   68篇
中国医学   14篇
肿瘤学   57篇
  2023年   7篇
  2022年   28篇
  2021年   51篇
  2020年   23篇
  2019年   34篇
  2018年   31篇
  2017年   32篇
  2016年   31篇
  2015年   35篇
  2014年   46篇
  2013年   60篇
  2012年   108篇
  2011年   65篇
  2010年   33篇
  2009年   18篇
  2008年   51篇
  2007年   52篇
  2006年   54篇
  2005年   46篇
  2004年   37篇
  2003年   26篇
  2002年   24篇
  2001年   29篇
  2000年   19篇
  1999年   14篇
  1998年   11篇
  1997年   3篇
  1996年   5篇
  1995年   8篇
  1994年   5篇
  1993年   3篇
  1992年   9篇
  1991年   7篇
  1990年   7篇
  1989年   8篇
  1988年   5篇
  1987年   8篇
  1986年   11篇
  1985年   8篇
  1981年   3篇
  1980年   4篇
  1979年   10篇
  1978年   7篇
  1976年   3篇
  1974年   3篇
  1973年   3篇
  1970年   3篇
  1969年   4篇
  1968年   4篇
  1967年   2篇
排序方式: 共有1113条查询结果,搜索用时 15 毫秒
91.
Maturation of hematopoietic stem cells (HSCs) from fetal to adult state and differentiation to progenitors are thought to follow a one-way street. In this issue of Genes & Development, He and colleagues (pp. 1613-1627) show that overexpression of Sox17 can convert adult multipotential progenitors to self-renewing HSCs that possess fetal properties. These findings challenge the irreversibility of hematopoietic development, and open up new perspectives to understand the different forms of HSC self-renewal at distinct stages of ontogeny and during transformation.  相似文献   
92.
The purpose of this study was to determine the cost savings from a societal perspective for recombinant human Bone Morphogenetic Protein-2 (rhBMP-2) in grade III A and B open tibial fractures treated with a locked intramedullary nail and soft-tissue management in the UK, Germany, and France. Health care system costs (direct health care costs) and costs for productivity losses (indirect health care costs) were calculated using the raw data from the Bone Morphogenetic Protein Evaluation Group in Surgery for Tibial Trauma “BESTT study”. Return-to-work time for estimation of productivity losses was assumed to correspond with the time of fracture healing. For calculation of secondary interventions costs and productivity losses the respective 2007/2008 national tariffs for surgical procedures and average national wages for the UK, Germany, and France were used. For a 1 year perspective, overall treatment costs per patient after the initial surgery of the control vs. the rhBMP-2 group were €44,757 vs. €36,847 for the UK, €50,197 vs. €40,927 for Germany and €48,766 vs. €39,474 for France in favour of rhBMP-2 with overall savings overall savings per case of rhBMP-2 treatment of €7911 for the UK, €9270 for Germany, and €9291 for France which was mainly due to reduced productivity losses by significant faster fracture healing in the rhBMP-2 group (p = 0.01). These savings largely offset the upfront price of rhBMP-2 of €2266 (£1790) in the UK, €2970 in Germany, and €2950 in France. Total net savings can be estimated to be €9.6 million for the UK, €14.5 million for Germany, and €11.4 million for France. The results depend on the methodology used particularly for calculation of productivity losses and return-to-work time which was assumed to correspond with fracture healing time. In summary, despite the apparent high direct cost of rhBMP-2 in grade III A and B open tibial fractures, at a national level there are net cost savings from a societal perspective for all three countries.  相似文献   
93.
CONTEXT: Peripubertal obesity is associated with abnormal sex steroid concentrations, but the timing of onset and degree of these abnormalities remain unclear. OBJECTIVE: The objective of the study was to assess the degree of hyperandrogenemia across puberty in obese girls and assess overnight sex steroid changes in Tanner stage 1-3 girls. DESIGN: This was a cross-sectional analysis. SETTING: The study was conducted at general clinical research centers. SUBJECTS: Thirty normal-weight (body mass index for age < 85%) and 74 obese (body mass index for age >or= 95%) peripubertal girls. INTERVENTION: Blood samples (circa 0500-0700 h) were taken while fasting. Samples from the preceding evening (circa 2300 h) were obtained in 23 Tanner 1-3 girls. MAIN OUTCOME MEASURES: Hormone concentrations stratified by Tanner stage were measured. RESULTS: Compared with normal-weight girls, mean free testosterone (T) was elevated 2- to 9-fold across puberty in obese girls, whereas fasting insulin was 3-fold elevated in obese Tanner 1-3 girls (P < 0.05). Mean LH was lower in obese Tanner 1 and 2 girls (P < 0.05) but not in more mature girls. In a subgroup of normal-weight Tanner 1-3 girls (n = 17), mean progesterone (P) and T increased overnight 2.3- and 2.4-fold, respectively (P 相似文献   
94.

Background:

The spinal cord injured patients if congregated early in spinal units where better facilities and dedicated expert care exist the outcome of treatment and rehabilitation, can be improved. The objective of this study is to find out the various factors responsible for a delay in the presentation of spinal injury patients to the specialized spinal trauma units and to suggest steps to improve the quality of care of the spinal trauma patients in the Indian setup.

Materials and Methods:

Sixty patients of traumatic spinal cord injury admitted for rehabilitation between August 2005 and May 2006 were enrolled into the study and their data was analyzed.

Results:

Eighty-five per cent of the spinal cord injured patients were males and the mean age was 34 years (range 13-56 years). Twenty-nine (48.33%) of the spinal injuries occurred due to fall from height. There was an average of 45 days (range 0-188 days) of delay in presentation to a specialized spinal unit and most of the time the cause for the delay was unawareness on the part of patients and/or doctors regarding specialized spinal units. In 38 (62.5%) cases the mode of transportation of the spinal cord injured patient to the first visited hospital was by their own conveyance and the attendants of the patients did not have any idea about precautions essential to prevent neurological deterioration. Seventeen (28.33%) patients were given injection solumedrol with conservative treatment, 35 (60%) patients were given only conservative treatment and seven patients were operated (11.66%) upon at initially visited hospital. Of the seven patients operated five were fixed with posterior Harrington instrumentation (71.42%) and two (28.57%) were operated by short segment posterior pedicle screw fixation. None of the patients were subjected to physiotherapy-assisted transfers or wheel chair skills or even basic postural training, proper bladder/ bowel training program and sitting balance.

Conclusion:

Awareness on the part of the general population, attendants of the patients, clinical and paraclinical team regarding spinal cord injury needs to be addressed. Safe mode of transportation of spinal cord injured patient and early presentation at tertiary spinal care center with comprehensive spinal trauma care team should be stressed upon.  相似文献   
95.
We examined the possible molecular mechanisms underlying the cytotoxicity and anticarcinogenic potential of Mentha leaf extracts (petroleum ether, benzene, chloroform, ethyl acetate, methanol, and water extracts) on 6 human cancer (HeLa, MCF-7, Jurkat, T24, HT-29, MIAPaCa-2) and normal (IMR-90, HEK-293) cell lines. Of all the extracts tested, chloroform and ethyl acetate extracts of M piperita showed significant dose- and time-dependent anticarcinogenic activity leading to G1 cell cycle arrest and mitochondrial-mediated apoptosis, perturbation of oxidative balance, upregulation of Bax gene, elevated expression of p53 and p21 in the treated cells, acquisition of senescence phenotype, while inducing pro-inflammatory cytokines response. Our results provide the first evidence of direct anticarcinogenic activity of Mentha leaf extracts. Further, bioassay-directed isolation of the active constituents might provide basis for mechanistic and translational studies for designing novel anticancer drugs to be used alone or as adjuvant for prevention of tumor progression and/or treatment of human malignancies.  相似文献   
96.
Tuberculosis (TB) has become a global epidemic again with emergence of HIV/AIDS and multi-drug resistant strains of TB. Female genital tuberculosis (GT) is typically a disease of young women and its occurrence in post menopausal women is rare. Amongst the genital disorders, GT is the most baffling especially because of its various presentations. So GT is notorious for evading diagnosis. A series of cases of females GT between the age 25 yrs to 40 yrs is being reported with women having spectrum of clinical features, creating diagnostic dilemma and so final diagnosis by histopathology after laparotomy. So a high degree of suspicion aided by intensive investigations may be required for the diagnosis of GT. Medical therapy is the main treatment, however some do need surgery. Research needs to be continued for early establishment of timely diagnosis of GT and modalities of effective therapies.  相似文献   
97.
98.
Surgical treatment of tendon ruptures and lacerations is currently the most common therapeutic modality. Tendon repair in the hand involves a slow repair process, which results in inferior repair tissue and often a failure to obtain full active range of motion. The initial stages of repair include the formation of functionally weak tissue that is not capable of supporting tensile forces that allow early active range of motion. Immobilization of the digit or limb will promote faster healing but inevitably results in the formation of adhesions between the tendon and tendon sheath, which leads to friction and reduced gliding. Loading during the healing phase is critical to avoid these adhesions but involves increased risk of rupture of the repaired tendon. Understanding the biology and organization of the native tendon and the process of morphogenesis of tendon tissue is necessary to improve current treatment modalities. Screening the genes expressed during tendon morphogenesis and determining the growth factors most crucial for tendon development will likely lead to treatment options that result in superior repair tissue and ultimately improved functional outcomes.  相似文献   
99.
In Kenya, most people especially in rural areas use traditional medicine and medicinal plants to treat many diseases including malaria. Malaria is of national concern in Kenya, in view of development of resistant strains of Plasmodium falciparum to drugs especially chloroquine, which had been effective and affordable. There is need for alternative and affordable therapy. Many antimalarial drugs have been derived from medicinal plants and this is evident from the reported antiplasmodial activity. The aim of the study was to document medicinal plants traditionally used to treat malaria by the Digo community of Kwale district. Traditional health practitioners were interviewed with standardized questionnaires in order to obtain information on medicinal plants traditionally used for management of malaria. Twenty-five species in 21 genera and 16 families were encountered during the study. Celestraceae, Leguminosae and Rubiaceae families represented the species most commonly cited. Three plant species, namely; Maytenus putterlickioides, Warburgia stuhlmannii and Pentas bussei are documented for the first time for the treatment of malaria.  相似文献   
100.
PURPOSE: This study evaluated the maximum grip strength in a position of elbow extension versus flexion as a diagnostic tool in the assessment of a patient with suspected lateral epicondylitis (LE). METHODS: From our database we identified 81 patients with grip strength measurements and the diagnosis of LE. From these patient records we collected grip strength measurements with the elbow in full extension and with the elbow in 90 degrees of flexion for the affected and the healthy extremity. We then compared 2 values: the pretreatment grip strength in flexion and extension for the affected extremity and the pretreatment grip strengths of the nonaffected extremity compared with the affected extremity. Grip strengths were compared with paired and unpaired 2-tailed t tests. RESULTS: Grip strength was no different in flexion and extension for the healthy extremity and 29% stronger in flexion than in extension for the affected extremity. The affected arm averaged 50% of the strength of the healthy arm in extension and 69% of the strength of the healthy arm in flexion. These differences were statistically significant. An 8% difference in grip strength between flexion and extension was found to be 83% accurate in distinguishing the affected from the unaffected extremities. CONCLUSIONS: The measurement of extension grip strength is a useful objective tool to aid in the diagnosis of LE. In patients with LE, the grip strength decreases as one moves from a position of flexion to a position of extension.  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