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   7852篇
  免费   590篇
  国内免费   20篇
耳鼻咽喉   63篇
儿科学   307篇
妇产科学   214篇
基础医学   1292篇
口腔科学   117篇
临床医学   932篇
内科学   1549篇
皮肤病学   141篇
神经病学   1060篇
特种医学   91篇
外科学   612篇
综合类   61篇
一般理论   14篇
预防医学   1008篇
眼科学   55篇
药学   432篇
中国医学   14篇
肿瘤学   500篇
  2023年   44篇
  2022年   44篇
  2021年   222篇
  2020年   129篇
  2019年   228篇
  2018年   221篇
  2017年   158篇
  2016年   190篇
  2015年   204篇
  2014年   276篇
  2013年   427篇
  2012年   624篇
  2011年   608篇
  2010年   325篇
  2009年   270篇
  2008年   465篇
  2007年   557篇
  2006年   507篇
  2005年   494篇
  2004年   459篇
  2003年   442篇
  2002年   390篇
  2001年   77篇
  2000年   36篇
  1999年   50篇
  1998年   101篇
  1997年   75篇
  1996年   62篇
  1995年   56篇
  1994年   51篇
  1993年   67篇
  1992年   34篇
  1991年   29篇
  1990年   35篇
  1989年   31篇
  1988年   29篇
  1987年   27篇
  1986年   21篇
  1985年   23篇
  1984年   35篇
  1983年   19篇
  1982年   43篇
  1981年   45篇
  1980年   24篇
  1979年   16篇
  1978年   23篇
  1977年   18篇
  1976年   15篇
  1971年   12篇
  1970年   11篇
排序方式: 共有8462条查询结果,搜索用时 15 毫秒
11.
Infants living in an orphanage (n = 22) in Romania were assessed on the Test of Sensory Functions in Infants (TSFI). Testing of the institutionalized infants was done before and 6 months after an enriched caregiver intervention program. Results showed significant changes in areas of reactivity to tactile deep pressure, visual-tactile integration, oculomotor control, reactivity to vestibular stimulation and total test responses. No significant changes occurred in the area of adaptive motor functions. Effects of sensory deprivation resulting from institutional settings and changes that can occur from enriched caregiver environments are discussed.  相似文献   
12.
Laparoscopic management of ureteral endometriosis: our experience   总被引:2,自引:0,他引:2  
STUDY OBJECTIVE: Ureteral endometriosis is rare, accounting for less than 0.3% of all endometriotic lesions. The aim of our study is to evaluate the prevalence of extrinsic ureteral endometriosis in women undergoing laparoscopic surgery for severe endometriosis and to suggest that laparoscopic ureterolysis represents a mandatory measure in all cases to avoid ureteral injury. METHODS: A retrospective analysis was performed of all cases of patients who underwent laparoscopic surgery for severe endometriosis at the departments of obstetrics and gynecology at CMCO-SIHCUS and Hautepierre Hospital, Strasbourg, from November 2004 through January 2006. MEASUREMENTS AND MAIN RESULTS: We recorded 54 patients with a mean age of 31 years and a mean body mass index of 21.9. Reported symptoms were dysmenorrhea (88%), severe dyspareunia (88%), severe pelvic pain (38.8%), and infertility (74%). Five women presented with dysuria, frequency, recurrent urinary tract infections, and pain in the renal angle, and 2 patients had hydronephrosis. We observed 3 patients (5.6%) with ureteral stenosis, 35 (64.8%) with adenomyotic tissue surrounding the ureter without stenosis, and 16 (29.6%) with adenomyotic tissue adjacent to the ureter. It was on the left side in 47.4% of cases, on the right side in 31.6% cases, and bilaterally in 21% of cases. In 9 patients, ureteral involvement was associated with bladder endometriosis (16.7%). In all patients, ureterolysis was performed. There was 1 case of ureteral injury during the procedure, 2 of transitory urinary retention, and 1 of uretero-vaginal fistula after surgery. During the first year of follow-up, the disease recurred in 4 patients, with no evidence of the disease in the urinary tract. CONCLUSION: Conservative laparoscopic surgery to relieve ureteral obstruction and remove pathologic tissue is the management of choice. Resection of part of the ureter should be performed only in exceptional cases. Ureterolysis should be performed in all patients before endometriotic nodule resection to recognize and prevent any ureteral damage.  相似文献   
13.
14.
15.
16.

Background  

This study compared the prognostic value of exercise single-photon emission computed tomographic (SPECT) thallium imaging with that of treadmill exercise score in medically treated patients with coronary artery disease (CAD)  相似文献   
17.
β-Adrenergic receptors (βAR) in the medial nuclei of tractus solitarii (m-NTS) and area postrema (AP) may bind to catecholamines released from neurons, whereas only the AP has fenestrated capillaries allowing access to circulating catecholamines. Since varied autonomic responses are seen following βAR activation of the dorsal vagal complex, including the m-NTS and AP, we hypothesized that there might be a cellular basis for varied responses to βAR stimulation that depends pn the differential access to circulating catecholamines. Therefore, we comparatively examined the ultrastructural localization of the βAR in relation to catecholaminergic neurons in these regions. An antibody directed against the C-terminal tail (amino acids 404–418) of hamster β-adrenergic receptor (βAR404) was used in this study. The localization of βAR404 was achieved by the avidin-biotin peroxidase complex (ABC) technique in combination with a pre-embed immunogold labeling method to localize tyrosine hydroxylase (TH), the catecholamine-synthesizing enzyme. Within m-NTS and at subpostremal border, labeling for βAR404 was evident along the intracellular surface of plasma membranes of small, apparently distal, astrocytic processes. Astrocytic processes with βAR404-immunoreactivity formed multiple, thin lamellae around TH-labeled and non-TH neuronal cell bodies and dendrites. βAR404-immunoreactive astrocytes also extended end-feet around blood vessels and surrounded groups of axon terminals that were directly juxtaposed to each other. Some, but not all, of these axons demonstrated TH-immunoreactivity. Fewer βAR404-immunoreactive astrocytes were detected in AP, regardless of their proximity to catecholaminergic processes or blood vessels. The present astrocytic localization of βAR404, together with the earlier, neuronal localization of βAR's third intracellular loop, suggest that the βAR may be substantially different between neurons and astrocytes. The regional difference in the prevalence of βAR404-immunoreactive astrocytes suggests that these receptive sites may either: (i) be preferentially activated by catecholamines released from terminals rather than circulating catecholamines; or (ii) be down-regulated in AP due to blood-born substances, such as catecholamines. The extensive localization of βAR in the border between m-NTS and AP also suggests that catecholaminergic activation of these astrocytes may dictate the degree of diffusion of catecholamines which are of neuronal or vascular origin. The specific localization of βAR404-immunoreactivity to the more distal portions of astrocytes suggests the possibility that astrocytes have restrictive distributions of βAR and that the β-adrenergic activation lead to morphological or chemical changes that are also localized to the distal portions of astrocytes. Additionally, the detection of βAR404 in astrocytes contacting non-TH-immunoreactive neurons suggests the possibility for catecholaminergic modulation of non-catecholaminergic neurons via the activation of astrocytes.  相似文献   
18.
19.
Objective. The Organ Donation Breakthrough Collaborative is a quality improvement initiative to encourage adoption of "best practices" for identifying potential donors and obtaining consent for deceased organ donation. We evaluate the impact of the first phase on organ donation rates.
Setting. We study donation rates in the 95 hospitals that participated in the first phase and a control group of 125 hospitals.
Design. We use a controlled pre/post design. The preperiod is the year before the start of the Collaborative (September 2002 to August 2003), the postperiod is the final 6 months of the first phase (March 2004 to August 2004).
Data. We use administrative data from the Organ Procurement and Transplantation Network to compute the conversion rate in each hospital group and time period. The conversion rate is the proportion of eligible donors who became actual donors.
Principal Findings. Preperiod conversion rates in Collaborative and control hospitals were similar: 52 and 51 percent, respectively. In the postperiod, the conversion rate increased to 60 percent among Collaborative hospitals and remained at 51 percent among control hospitals. The relative change was 8 percentage points (95 percent confidence interval: 2–13: p <.001).
Conclusions. Our findings suggest that the Breakthrough Collaborative led to an increase in donation rates at participating hospitals.  相似文献   
20.
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