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   2124篇
  免费   198篇
  国内免费   6篇
耳鼻咽喉   116篇
儿科学   173篇
妇产科学   83篇
基础医学   264篇
口腔科学   38篇
临床医学   236篇
内科学   437篇
皮肤病学   50篇
神经病学   168篇
特种医学   80篇
外科学   309篇
综合类   104篇
一般理论   5篇
预防医学   143篇
眼科学   10篇
药学   72篇
中国医学   3篇
肿瘤学   37篇
  2021年   31篇
  2019年   30篇
  2018年   33篇
  2017年   26篇
  2016年   21篇
  2015年   19篇
  2014年   41篇
  2013年   49篇
  2012年   82篇
  2011年   105篇
  2010年   56篇
  2009年   50篇
  2008年   78篇
  2007年   75篇
  2006年   84篇
  2005年   63篇
  2004年   56篇
  2003年   41篇
  2002年   52篇
  2001年   66篇
  2000年   75篇
  1999年   36篇
  1998年   30篇
  1997年   22篇
  1996年   34篇
  1995年   42篇
  1994年   32篇
  1993年   25篇
  1992年   82篇
  1991年   74篇
  1990年   64篇
  1989年   63篇
  1988年   53篇
  1987年   42篇
  1986年   54篇
  1985年   60篇
  1984年   57篇
  1983年   20篇
  1982年   17篇
  1981年   20篇
  1980年   22篇
  1979年   41篇
  1978年   19篇
  1977年   15篇
  1976年   18篇
  1975年   21篇
  1973年   28篇
  1972年   22篇
  1971年   24篇
  1967年   17篇
排序方式: 共有2328条查询结果,搜索用时 0 毫秒
11.
Small, patent cerebral aneurysms: atypical appearances at 1.5-T MR imaging   总被引:1,自引:0,他引:1  
Rolen  PB; Sze  G 《Radiology》1998,208(1):129
  相似文献   
12.
13.
Cranial sutures and craniometric points detected on MRI   总被引:2,自引:0,他引:2  
The main goal of the study was to determine on MRI the cranial sutures, the craniometric points and craniometric measurements, and to correlate these results with classical anthropometric measurements. For this purpose, we reviewed 150 cerebral MRI examinations considered as normal (Caucasian population aged 2049 years). For each examination we individualized 11 craniometric landmarks (Glabella, Bregma, Lambda, Opisthocranion, Opisthion, Basion, Inion, Porion, Infra-orbital, Eurion) and three measurements. Measurements were also calculated independently on 498 dry crania (Microscribe 3-DX digitizer). To validate the MRI procedure, we measured four dry crania by MRI and with compass or digital caliper gauges. Cranial sutures always appeared without signal (black), whatever the MRI sequence used, and they are better visualized with a 5 mm slice thickness (compact bone overlapping). Slice dynamic analysis and multiplanar reformatting allowed the detection of all craniometric points, some of these being more difficult to detect than others (Porion, Infra-orbital). The measurements determined by these points were as follows: VertexBasion height=135.66±6.56 mm; EurionEurion width=141.17±5.19 mm; GlabellaOpisthocranion length=181.94±6.40 mm. On the midline T1-weighted sagittal image, all median craniometric landmarks can be individualized and the GlabellaOpisthocranion length, VertexBasion height and parenchyma indices can be calculated. Craniometric points and measurements between these points can be estimated with a standard cerebral MRI examination, with results that are similar to anthropometric data.  相似文献   
14.
15.
16.
Congenital laryngeal anomalies may occur as a result of defects in normal prenatal development. They are associated with a broad spectrum of symptoms and require treatment ranging from observation alone to complex open airway surgery. The treating otolaryngologist must organize a management strategy focused on timely diagnosis, ensuring a safe airway, and maximum conservation of respiratory, phonatory, and swallowing ability.  相似文献   
17.
The newly approved use of an Atovaquone (Mepron) suspension for treating mild to moderate Pneumocystis carinii (PCP) in patients unable to tolerate trimethoprim-sulfamethoxazole (TMP-SMX), has shown that it is twice as bioavailable compared with the previously licensed tablet formulation. However, Atovaquone use has produced more deaths than TMP-SMX, a problem that may in part be due to its lack of a broad antibacterial spectrum.  相似文献   
18.
19.
The fact that certain ultraviolet (UV) filters used in cosmetics display estrogenic activity prompted us to study potential actions on androgen receptors (AR) in the human breast carcinoma cell line MDA-kb2, which expresses functional endogenous AR and glucocorticoid receptors (GR) and is stably transfected with a luciferase reporter plasmid. Dihydrotestosterone (DHT), methyltrienolone (R1881), methyltestosterone, danazol, and androstenedione increased luciferase activity, with EC50 values between 0.11 nM (R1881), 0.14 nM (DHT), and 73.5 nM (androstenedione). DHT-induced luciferase gene expression was inhibited by nonsteroidal antiandrogens, hydroxyflutamide, flutamide, bicalutamide, and vinclozolin. In contrast, the steroidal AR agonist/antagonist cyproterone actetate showed agonistic activity in the absence and presence of DHT, which was not blocked by hydroxyflutamide and thus seems not to be mediated by AR. GR-mediated activation of luciferase by dexamethasone was 100 times less potent than DHT and was not antagonized by hydroxyflutamide. The cell line was used for screening of UV filters, benzophenone-3 (Bp-3), benzophenone-4, 3-benzylidene camphor, 4-methylbenzylidene camphor, butyl-methoxy-dibenzoylmethane, homosalate (HMS), octyl-dimethyl-PABA, and octyl-methoxycinnamate. Two of these, Bp-3 and HMS, antagonized DHT-induced AR activation below cytotoxic concentrations, with IC50 of 5.57 10-6 M (HMS) and 4.98 10-6 M (Bp-3). None of the eight UV filters displayed agonistic activity when tested alone, but high concentrations of Bp-3 induced an increase of luciferase activity in the presence of dexamethasone, which was not blocked by hydroxyflutamide or the estrogen antagonist, ICI 182,780. These data indicate that the UV filters Bp-3 and HMS possess antiandrogenic activity in vitro in addition to estrogenic activity.  相似文献   
20.
BACKGROUND: We have previously reported the use of a hospital based respiratory nurse service (Acute Respiratory Assessment Service, ARAS) to support home treatment of patients with exacerbations of chronic obstructive pulmonary disease (COPD). A controlled trial was undertaken to compare early discharge with home treatment supported by respiratory nurses with conventional hospital management of patients admitted with exacerbations of COPD. METHODS: Patients with COPD admitted as emergencies were identified the next working day. They were eligible for inclusion in the study if the differential diagnosis included an exacerbation of COPD, but were excluded if other medical conditions or acidotic respiratory failure required inpatient investigation or management. Of 360 patients reviewed, 209 were being assessed for other active medical problems and were excluded, 33 potential participants were already involved in research studies and so were ineligible, and 37 did not wish to participate in the study. Eighty one patients were randomised to receive conventional inpatient care (n=40) or to planned early discharge the next working day (n=41). Those discharged early continued treatment at home under the supervision of specialist respiratory nurses. Outcome measures were readmission, additional hospital days, and deaths within 60 days of initial admission. Process measures included number of visits, duration of follow up by the respiratory nurse, and additional treatment provided to support early discharge. RESULTS: On an intention to treat basis, a policy of early discharge reduced inpatient stay from a mean of 6.1 (range 1-13) days with conventional management to 3.2 (1-16) days with an early discharge policy. Twelve patients (30% conventional management, 29.3% early discharge) were readmitted in each group giving a mean difference in readmission of 0.7% (95% CI of the difference -19.2 to 20.6). In the conventional management group readmitted patients spent a mean of 8.75 additional days in hospital compared with 7.83 days in the early discharge group, giving a mean difference of 0.92 days (95% CI of the difference -6.5 to 8.3). There were two deaths (5%) in the conventional management group and one (2.4%) in the early discharge group, a mean difference of 2.6% (95% CI of the difference -5.7 to 10.8). CONCLUSIONS: Patients with acute exacerbations of COPD uncomplicated by acidotic respiratory failure or other medical problems can be discharged home earlier than is current practice with support by visiting respiratory nurses. No difference was found in the subsequent need for readmission.  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