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   13129篇
  免费   1509篇
  国内免费   66篇
耳鼻咽喉   128篇
儿科学   418篇
妇产科学   271篇
基础医学   2158篇
口腔科学   298篇
临床医学   1639篇
内科学   2542篇
皮肤病学   260篇
神经病学   1050篇
特种医学   518篇
外科学   1665篇
综合类   335篇
一般理论   16篇
预防医学   1483篇
眼科学   147篇
药学   1080篇
  1篇
中国医学   8篇
肿瘤学   687篇
  2021年   216篇
  2020年   105篇
  2019年   195篇
  2018年   221篇
  2017年   169篇
  2016年   208篇
  2015年   227篇
  2014年   298篇
  2013年   443篇
  2012年   576篇
  2011年   608篇
  2010年   326篇
  2009年   336篇
  2008年   538篇
  2007年   570篇
  2006年   579篇
  2005年   543篇
  2004年   532篇
  2003年   482篇
  2002年   444篇
  2001年   403篇
  2000年   428篇
  1999年   366篇
  1998年   202篇
  1997年   179篇
  1996年   174篇
  1995年   153篇
  1994年   137篇
  1993年   139篇
  1992年   272篇
  1991年   296篇
  1990年   277篇
  1989年   281篇
  1988年   270篇
  1987年   247篇
  1986年   221篇
  1985年   223篇
  1984年   204篇
  1983年   163篇
  1982年   111篇
  1981年   127篇
  1980年   116篇
  1979年   172篇
  1978年   166篇
  1977年   136篇
  1976年   117篇
  1975年   107篇
  1974年   143篇
  1973年   129篇
  1972年   100篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
32.
We examined the time course effects of continuous PTH on cortical bone and mechanical properties. PTH increased cortical bone turnover and induced intracortical porosity with no deleterious effect on bone strength. Withdrawal of PTH increased maximum torque to failure and stiffness with no change in energy absorbed. INTRODUCTION: The skeletal response of cortical bone to parathyroid hormone (PTH) is complex and species dependent. Intermittent administration of PTH to rats increases periosteal and endocortical bone formation but has no known effects on intracortical bone turnover. The effects of continuous PTH on cortical bone are not clearly established. MATERIALS AND METHODS: Eighty-four 6-month-old female Sprague-Dawley rats were divided into three control, six PTH, and two PTH withdrawal (WD) groups. They were subcutaneously implanted with osmotic pumps loaded with vehicle or 40 microg/kg BW/day human PTH(1-34) for 1, 3, 5, 7, 14, and 28 days. After 7 days, PTH was withdrawn from two groups of animals for 7 (7d-PTH/7d-WD) and 21 days (7d-PTH/21d-WD). Histomorphometry was performed on periosteal and endocortical surfaces of the tibial diaphysis in all groups. microCT of tibias and mechanical testing by torsion of femora were performed on 28d-PTH and 7d-PTH/21d-WD animals. RESULTS AND CONCLUSIONS: Continuous PTH increased periosteal and endocortical bone formation, endocortical osteoclast perimeter, and cortical porosity in a time-dependent manner, but did not change the mechanical properties of the femur, possibly because of addition of new bone onto periosteal and endocortical surfaces. Additionally, withdrawal of PTH restored normal cortical porosity and increased maximum torque to failure and stiffness. We conclude that continuous administration of PTH increased cortical porosity in rats without having a detrimental effect on bone mechanical properties.  相似文献   
33.
This study investigates functional disability among some of the nation's most vulnerable older adults: rural Medicaid recipients. Data were provided by 221 older adults (mean age = 75.9 years; 82% women) who were receiving community-based long-term care services through Medicaid. Participants self-reported functional ability involving the completion of six basic activities of daily living (BADLs), three cognitive instrumental activities of daily living (IADLS), and four physical IADLs. Self-reports of depressed affect and the number of physical health conditions were also obtained. Path analysis was used to examine all of the associations among age, gender, number of chronic health conditions, depressed affect and functional disability. The tested model was significant [chi2 (DF = 3, n = 221) = 5.052, p = 0.168; TLI = 0.945; CFI = 0.992; RMSEA = 0.056] and explained 45.1% of the variance in BADL disability. Depressed affect significantly predicted disability in cognitive IADLs and physical IADLs, which predicted disability in BADLs. Age and gender had indirect effects on BADL, through their association with cognitive IADLs and physical IADLs. The number of chronic health conditions exerted both indirect and direct effects on BADL disability. Results are discussed within the context of the growing literature that suggests the importance of psychological variables as predictors of functional disability. Moreover, we discuss whether community-based long-term care is appropriate for older adults with high levels of functional disability.  相似文献   
34.
35.

Background  

Studies have found that deaf individuals have higher rates of psychiatric disorder than those who are hearing, while at the same time encountering difficulties in accessing mental health services. These factors might increase the risk of suicide. However, the burden of suicidal behaviour in deaf people is currently unknown.  相似文献   
36.
Over 20 years ago, the Birmingham Blood Centre established a facility for the cryopreservation of bone marrow (BM) for patients in the West Midlands suffering from haematopoietic disorders and for whom a bone marrow transplant was indicated. Today, the use of mobilised peripheral blood (PBSC) has overtaken bone marrow as the source of stem cells for transplantation and the numbers of patients benefitting and the diversity of conditions being treated has increased enormously. Allogeneic transplants, using stem cells from healthy donors, have become increasingly successful as a result of an improving understanding of the complexities of the HLA histocompatibility system. Additionally umbilical cord blood (HUC), which in the 1980s was recognised as a source of stem cells, can now be collected and used for transplantation. As scientific knowledge and the clinical management of patients has advanced, so too have laboratory methods for manipulating cell products to enrich or deplete certain cell populations (e.g. by CD34+cell selection) in order to minimise potentially fatal graft-versus-host disease (GVHD) or to eliminate tumour cells in the case of autologous patients. Donor lymphocytes (DLI) may also be collected and used to aid a graft-versus-leukaemia (GVL) effect. The laboratory is currently developing protocols for immunotherapy using virus-specific T cells which can be prepared and infused to combat potentially fatal CMV disease post-transplant. Clinical trials of vaccines employing tumour specific dendritic cells for treating patients with hepatocellular carcinoma (HCC) and metastatic melanoma (MM), which do not respond to conventional treatments, are also underway. The advances and expansion in the Stem Cell and Immunotherapy (SCI) service in Birmingham over the last 10 year period are reflected in the table below:
 
  相似文献   
37.
This study provides additional information on the psychometric properties of the Sexual Aversion Scale (SAS). Results suggest a positive relationship between sexual aversion, generalized anxiety, and history of sexual victimization. Variables such as age and religiosity were unrelated to scores on the SAS, although females reported significantly more sexual anxiety than males. The factor structure of the SAS is described and suggests that sexual aversion is a multifaceted problem with at least three and possibly four different dimensions.  相似文献   
38.
Abstract The aim of the present paper was to describe some formative projects on work integration of patients with epilepsy and mild cognitive deficits, so that similar initiatives may be promoted. The different phases of the formative projects were described: the inclusion criteria, the selection of participants, the assessment instruments, the courses themselves and the final results in terms of working experience. Thirteen participants were selected for each course. Patients were treated in different Lombardy Epilepsy departments, which addressed them to the Epilepsy Center, S. Paolo Hospital, Milan, where the selection took place. Seventy percent of the participants in the formative courses found a job in 1 year, even though most of the positions were temporary. The work integration seemed to be mainly related to the level of intelligence and to verbal memory. We stress the importance of organising similar courses in the future, in the context of wider networks. This will help more patients in acquiring both economic and psychological autonomy from their families.  相似文献   
39.
Proluminal movement of 3H-testosterone and 3H-sucrose from peritubular to intratubular fluids of the adult rat testis and epididymis was investigated by using in vivo microperifusion and subsequent micropuncture of seminiferous tubules and caput, corpus, and cauda epididymal tubules. Tubules were perifused with Minimum Essential Medium containing 3H-testosterone or 3H-sucrose. 14C-polyethyleneglycol was included in the perifusion fluid as a marker for contamination of intraluminal fluid by interstitial fluid. Radioactivity of isotopes in perifusion and intraluminal fluids was determined at one and two hours after perifusion and the percentage of peritubular isotopes appearing in intraluminal fluid was determined. Net entry of 3H-sucrose into the seminiferous and epididymal tubules was significantly reduced. Proluminal movement of 3H-androgen across the seminiferous epithelium was also restricted. In contrast, intraluminal 3H-androgen concentrations in caput epididymal fluid were 200 to 300% of those in peritubular fluid at both one and two hours after perifusion. Similar results were found in the corpus epididymidis. 3H-androgen concentrations in cauda epididymal fluid were approximately 125% of peritubular isotope concentrations. The exact mechanism underlying this uphill proluminal movement of 3H-androgen into the rat epididymal lumen remains to be elucidated.  相似文献   
40.
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