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   11224篇
  免费   598篇
  国内免费   37篇
耳鼻咽喉   174篇
儿科学   723篇
妇产科学   153篇
基础医学   1004篇
口腔科学   214篇
临床医学   905篇
内科学   2896篇
皮肤病学   279篇
神经病学   710篇
特种医学   285篇
外科学   1620篇
综合类   225篇
一般理论   2篇
预防医学   503篇
眼科学   426篇
药学   671篇
中国医学   20篇
肿瘤学   1049篇
  2023年   53篇
  2022年   118篇
  2021年   397篇
  2020年   193篇
  2019年   260篇
  2018年   372篇
  2017年   211篇
  2016年   254篇
  2015年   257篇
  2014年   390篇
  2013年   468篇
  2012年   746篇
  2011年   727篇
  2010年   408篇
  2009年   315篇
  2008年   568篇
  2007年   637篇
  2006年   560篇
  2005年   477篇
  2004年   475篇
  2003年   394篇
  2002年   382篇
  2001年   271篇
  2000年   240篇
  1999年   221篇
  1998年   105篇
  1997年   61篇
  1996年   53篇
  1995年   65篇
  1993年   45篇
  1992年   170篇
  1991年   176篇
  1990年   171篇
  1989年   152篇
  1988年   141篇
  1987年   130篇
  1986年   112篇
  1985年   106篇
  1984年   107篇
  1983年   75篇
  1982年   52篇
  1981年   43篇
  1980年   39篇
  1979年   84篇
  1978年   40篇
  1977年   62篇
  1974年   49篇
  1972年   48篇
  1970年   43篇
  1969年   38篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
1.
2.
OBJECTIVE: To investigate whether orofacial tardive dyskinesia (OTD) is associated with frontal lobe dysfunction and whether either are related to the coping abilities independent of psychiatric symptoms in older people with psychotic disorders. METHODS: A total of 52 patients, aged over 65 years or over, who satisfied International Classification of Diseases, Tenth Revision criteria for psychotic disorders (F20-F29) were recruited into the study. OTD was measured using the Abnormal Involuntary Movements Scale and Waddington et al.'s (1993) criteria. Neuropsychological measures were specifically selected to assess different aspects of frontal function and coping was measured using a semistructured interview. Psychiatric symptoms were assessed using the Positive and Negative Syndrome Scale (PANSS). RESULTS: Patients with OTD showed more severe global cognitive impairment compared to patients without OTD. Group differences on measures of frontal lobe dysfunction were not maintained following adjustment for global cognitive impairment. Patients with OTD did not differ from patients without OTD on coping measures. Scores on the general psychopathology subscale of the PANSS, which includes symptoms associated with depression and anxiety, consistently predicted patients' negative perceptions of stressors and appraisals of coping, but cognitive impairment did not predict coping independent of symptoms. CONCLUSION: The association between coping and general psychopathology in older patients with psychosis warrants further investigation as both variables may be amenable to psychological interventions.  相似文献   
3.
Head movement presents a continuing problem in PET studies. Head restraint minimizes movement but is unreliable, resulting in the need to develop alternative strategies. These include frame-by-frame (FBF) realignment or use of motion tracking (MT) during the scan to realign PET acquisition data. Here we present a comparative analysis of these 2 methods of motion correction. METHODS: Eight volunteers were examined at rest using (11)C-raclopride PET with the radioligand administered as a bolus followed by constant infusion to achieve steady state. Binding potential (BP) was estimated using the ratio method during 2 periods of the scan at steady state. Head movement was compensated by using coregistration between frames (FBF) and 3 methods using MT measurements of head position acquired with a commercially available optical tracking system. RESULTS: All methods of realignment improved test-retest reliability and noise characteristics of the raw data, with important consequences for the power to detect small changes in radiotracer binding, and the potential to reduce false-positive and false-negative results. MT methods were superior to FBF realignment using coregistration on some indices. CONCLUSION: Such methods have considerable potential to improve the reliability of PET data with important implications for the numbers of volunteers required to test hypotheses.  相似文献   
4.
Ehlers-Danlos syndrome – vascular type, the only lethal form, is rarely reported in dermatology literature. It is characterized by translucent, atrophic skin, easy bruising, arterial, intestinal and/or uterine fragility manifesting as varicose veins, aneurysms and vascular/visceral/uterine rupture. As its dermatopathologic features are not well elucidated, diagnosis is often made after a catastrophic complication or at autopsy. This 36 year-old non-consanguineous male had brown-black plaques with atrophy and frequent ulceration over legs and dorsal feet and tortuous varicose veins around ankles for the past 15 years. Perivenous skin was translucent and hypopigmented. He had multiple and ecchymotic keloids and small atrophic, pityriasis versicolor-like lesions over trunk. He did not have hypermobile/hyperextensible skin and joints and showed no systemic or investigative abnormality. Histopathologic features of atrophic lesion included blood extravasation in atrophic epidermis/dermis, focal clustering and dilatation of blood vessels, malformed vessel walls, abundant hemosiderin in the dermis and homogenously stained/whorled patterned collagen especially around blood vessels. Pathology of keloidal lesion showed new collagen and vascular fragility. These histopathologic features appear of diagnostic value especially in patients who have compatible clinical findings but cannot afford confirmation by biochemical testing for abnormal synthesis of type III procollagen or identification of mutations in the COL3A1 gene.  相似文献   
5.
V. Mehta 《Anaesthesia》2009,64(12):1279-1282
  相似文献   
6.
Primary tuberculous pathology in nasolpolypi is a rare condition. A case of bilateral ethmoidal polypi with tubercular lesion diagnosed on histopathologlcal examination is being reported and the available relevant literature has been reviewed.  相似文献   
7.
The return of fertility following discontinuation of norethisterone oenanthate (NET EN) 200 mg injectable contraceptive after use for a minimum period of six months or more was studied in 69 women who discontinued the method for planning pregnancy. Former users of copper intra-uterine device (CuT 200) were enrolled as a control group. Another 161 women who had discontinued NET EN due to other reasons (e.g. amenorrhoea, excessive bleeding or personal reasons) were also studied for return of fertility after ensuring that they were not using any other method of contraception and were exposed to the risk of pregnancy. The subjects from both groups were followed for a period of one year. The cumulative conception rates at one year were 72.5 and 83.6 per 100 subjects for ex-NET EN and ex-CuT 200 users who had discontinued the method for planning pregnancy and this difference was not statistically significant (P > 0.05). The median time for conception for ex-NET EN users was 7.8 months as compared to 3.7 months in ex-CuT 200 users but the cumulative conception rates at the end of one year show that future return of fertility in NET EN users does not appear to be adversely affected.

In 51 subjects who had discontinued NET EN due to amenorrhoea, the return of fertility was predictably slower and less. The return of fertility in subjects who discontinued NET EN for other reasons (e.g. excessive bleeding and other personal reasons) was similar to ex-NET EN and ex-CuT 200 users.  相似文献   

8.
9.
Object Intracranial aneurysms are rare in children and have different epidemiological, clinical, and morphological characteristics and outcome from those in adults. Materials and methods We analyzed demographic, clinical, radiologic features, treatment, and outcome in 55 patients <18 years of age, treated from Jan 1995 through December 2005. Results Intracranial aneurysms in children below 18 years constituted 4% of all intracranial aneurysms. Internal Carotid artery (ICA) bifurcation was the commonest location. About half of the aneurysms were complex. Three-fourth of the patients required surgical treatment. Two patients died, constituting 5% mortality. Two patients (5%) had poor outcome, whereas the majority (90%) had a favorable outcome. Conclusions Pediatric aneurysms have male predominance, higher incidence of clinical features of mass effect or seizures, high incidence of large, traumatic/mycotic aneurysms, associated illnesses and ICH/IVH and hydrocephalus, better Hunt and Hess grades at presentation, ICA bifurcation as the commonest site, and better outcome than their adult counterparts.  相似文献   
10.
In this study, we examined the impact of surgeon handedness on total knee arthroplasty (TKA) outcomes. From 1997 to 2001, a right-handed surgeon performed 728 primary TKAs while standing on the side of the operative extremity--377 on the right and 351 on the left. Extension and Knee Society Function and Pain scores were significantly better for right knees than for left knees 1 year after surgery. This is the first report that shows that handedness can play a role in TKA outcomes. Reasons for the difference have not been determined but may be related to dexterity or proprioception. A surgeon should be aware of this potential problem and take precautions to prevent diminished results when operating.  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