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   910篇
  免费   55篇
  国内免费   26篇
儿科学   27篇
妇产科学   3篇
基础医学   91篇
口腔科学   60篇
临床医学   84篇
内科学   145篇
皮肤病学   128篇
神经病学   200篇
特种医学   61篇
外科学   30篇
综合类   33篇
预防医学   34篇
眼科学   2篇
药学   68篇
中国医学   1篇
肿瘤学   24篇
  2020年   15篇
  2019年   10篇
  2018年   18篇
  2017年   8篇
  2016年   8篇
  2015年   12篇
  2014年   14篇
  2013年   19篇
  2012年   26篇
  2011年   22篇
  2010年   17篇
  2009年   26篇
  2008年   25篇
  2007年   45篇
  2006年   61篇
  2005年   50篇
  2004年   30篇
  2003年   28篇
  2002年   52篇
  2001年   37篇
  2000年   35篇
  1999年   34篇
  1998年   37篇
  1997年   20篇
  1996年   19篇
  1995年   14篇
  1994年   18篇
  1993年   16篇
  1992年   19篇
  1991年   18篇
  1990年   14篇
  1989年   19篇
  1988年   20篇
  1987年   21篇
  1986年   12篇
  1985年   16篇
  1984年   13篇
  1983年   10篇
  1982年   13篇
  1981年   6篇
  1980年   6篇
  1979年   12篇
  1978年   6篇
  1976年   7篇
  1973年   6篇
  1972年   7篇
  1970年   6篇
  1967年   6篇
  1966年   7篇
  1940年   4篇
排序方式: 共有991条查询结果,搜索用时 15 毫秒
1.
2.
周向东  周维善  王钟麒   《药学学报》1997,32(6):416-419
报道新化合物A-失碳-17β-羟基-17α-乙炔基-Δ3(5),9(10)-雌甾二烯-2-酮2的合成。文中探讨了用炔钾粗品对A-失碳-Δ3(5),9(10)-雌甾二烯-2,17-二酮1和A-失碳-6β,19-环氧-Δ3-雄甾-2,17-二酮3的选择性炔化,分别得标题化合物2(44%)及A-失碳-17β-羟基-17α-乙炔基-6β,19-环氧-Δ3雄甾-2-酮4(65%),4经还原性破开环氧、去羟甲基和去醋酰氧基合成了标题化合物2。四步总收率为34%。  相似文献   
3.
Hare  WS 《Radiology》1986,160(1):189-192
Two modified helical basket extractors are described that have increased the success rate of removing ureteral calculi using fluoroscopy from 63% to 92%. Initially a rather stiff and expandable basket with a 20-cm filiform tip is used with coaxial catheters and sheath (stage 1). If this procedure is unsuccessful, a basket with two long cable ends is passed from the nephrostomy out through the urethra (stage 2). When used with coaxial bladder catheters, this technique allows dilatation of the vesicoureteric junction and retrograde catheterization and injection of fluids or gas to dislodge the stone prior to extraction. In a series of 38 patients, stones were removed in all but three (a success rate of 92%). In five cases small stones (less than 5 mm) were not retrieved but subsequent studies were normal. Ureteral stones were found in the abdominal ureter in 28 cases, in the pelvic ureter in seven cases, and in multiple sites in three cases. Stones were larger than 1 cm in 27.7% of cases. Postextraction mucosal edema with reduced ureteral patency was common but usually cleared in 2-3 days. Occasional complications were related to the nephrostomy.  相似文献   
4.
This paper reports results of an open prospective study of 26 patients who met DSM-III criteria for panic disorder or agoraphobia with panic attacks. Cognitive-behavioral treatment alone produced clinically and statistically significant improvement in panic symptoms, including both full-blown and limited symptom episodes. In addition, the treatment produced improvement in associated symptoms of phobic avoidance and generalized anxiety. This work provides further preliminary indication of the usefulness of cognitive-behavioral strategies as an alternative to medication in symptom-oriented treatments.  相似文献   
5.
6.
This cross-sectional study used a semi-automated analysis technique to quantify regional brain cerebrospinal fluid (CSF) volumes derived from computed tomography (CT) in 84 healthy men ranging from 21 to 82 years of age and 28 patients meeting Research Diagnostic Criteria for alcohol dependence. The goals were to replicate an earlier CT study of an independent sample of alcoholic and control subjects (Pfefferbaum et al., 1988a; Zipursky et al., 1988) and to compare CT assessments of brain changes with magnetic resonance imaging (MRI) assessments made in the same alcoholic patients (Pfefferbaum et al., 1992). Regional brain changes associated with normal aging were derived by regression analysis, using CT data collected from the healthy control subjects. As in the earlier CT study and in the concurrent MRI study, ventricular and sulcal CSF volumes in alcoholic patients were greater than would be expected for their age. Furthermore, the present CT study replicated the previous CT and MRI findings of a positive relationship between age and CSF volume enlargement in alcoholic patients over and above the normal age-related increase in CSF volume, suggesting greater vulnerability of the aging brain to alcohol. Comparison of CT-and MRI-derived estimates of ventricular and cortical sulcal volume revealed high correlations (>0.80). MRI and CT produced similar absolute ventricular volumes, while MRI produced larger sulcal volume estimates than did CT. The difference in sulcal volume estimate may be due to differences between CT and MRI in slice thickness and sensitivity to partial volume effects.  相似文献   
7.
Retrorenal colon: implications for percutaneous diskectomy   总被引:1,自引:0,他引:1  
Helms  CA; Munk  PL; Witt  WS; Davis  GW; Morris  J; Onik  G 《Radiology》1989,171(3):864-865
It has been recommended that computed tomography (CT) with the patient prone be performed in every patient undergoing percutaneous diskectomy; this would enable detection of a retrorenal location of the colon, which could interfere with the percutaneous procedure. In this evaluation of 346 prone CT studies, only one patient (0.29%) was found to have retrorenal or retropsoas bowel that would have been perforated at diskectomy. Because of this extremely low prevalence, the performance of prone CT in every patient undergoing percutaneous lumbar diskectomy is not believed to be necessary.  相似文献   
8.
Pursuit eye movement dysfunction in obsessive-compulsive disorder.   总被引:3,自引:0,他引:3  
Disturbances in neural circuitry including the basal ganglia and prefrontal cortex have been hypothesized to be a cause of obsessive-compulsive disorder (OCD). Because eye movements are often impaired in neurologic diseases affecting these brain areas, oculomotor functioning was assessed in 17 unmedicated patients with OCD and in 25 normal controls. As compared with control subjects, patients with OCD demonstrated low-gain (slow) pursuit eye movements and an increased frequency of square wave jerk intrusions, but no increase in anticipatory saccades. In addition, several OCD patients showed an unusual pattern of intrusive, brief epochs of high-gain (fast) pursuit lasting on the order of 50 to 130 msec. These epochs of fast pursuit moved the eyes ahead of the target being tracked, and were terminated by corrective reversal saccades. Studies of eye movement abnormalities may provide an informative neurophysiologic approach for studying disturbances in basal ganglia and frontal cortical function that have been observed in functional neuroimaging and neuropsychological studies of OCD.  相似文献   
9.
Summary The DSM-III-R incorporates both distress (symptoms) and disability (impairment) in the definition of a psychiatric disorder. In psychiatric research there is a wide array of instruments used to measure symptom severity, but a limited selection for the assessment of impairment. The psychometric properties of one such instrument, The Sheehan Disability Scale (Sheehan 1983), are evaluated in this paper. The data analyzed come from two studies of patients with panic disorder, the Cross National Collaborative Panic Study-Phase I and the Panic Depression Study. In this report both the alpha coefficients and factor analyses indicate that the reliability of the scale is acceptable. The factor structure of the items and the sensitivity to change of their composite demonstrate satisfactory construct validity. The criterion-related validity is substantiated by the significant relationship between symptomatology and impairment. These analyses were limited to patients with panic disorder. Further work is needed to evaluate the instrument in assessing patients with other disorders.  相似文献   
10.
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