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   350篇
  免费   32篇
  国内免费   26篇
儿科学   20篇
妇产科学   17篇
基础医学   32篇
口腔科学   3篇
临床医学   30篇
内科学   70篇
皮肤病学   26篇
神经病学   27篇
特种医学   62篇
外科学   16篇
综合类   18篇
预防医学   22篇
眼科学   1篇
药学   40篇
中国医学   1篇
肿瘤学   23篇
  2023年   1篇
  2022年   4篇
  2021年   3篇
  2020年   2篇
  2019年   3篇
  2018年   16篇
  2017年   2篇
  2016年   4篇
  2015年   8篇
  2014年   2篇
  2013年   8篇
  2012年   9篇
  2011年   11篇
  2010年   10篇
  2009年   13篇
  2008年   9篇
  2007年   21篇
  2006年   22篇
  2005年   16篇
  2004年   7篇
  2003年   7篇
  2002年   14篇
  2001年   13篇
  2000年   10篇
  1999年   13篇
  1998年   19篇
  1997年   14篇
  1996年   18篇
  1995年   8篇
  1994年   14篇
  1993年   10篇
  1992年   11篇
  1991年   1篇
  1990年   7篇
  1989年   13篇
  1988年   13篇
  1987年   9篇
  1986年   7篇
  1985年   3篇
  1984年   4篇
  1983年   3篇
  1982年   11篇
  1981年   3篇
  1980年   3篇
  1979年   1篇
  1976年   3篇
  1975年   1篇
  1973年   2篇
  1969年   1篇
  1934年   1篇
排序方式: 共有408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.
5.
This Australian study monitored the effects of monthly plasmapheresis on donor serum IgG and IgM levels in 127 new and 124 established plasma donors who donated 1014 units over a five-month period. Of the 251 donors, 3% had reduced total serum protein (TSP) levels, 7% had low IgG levels and 12% had low IgM levels prior to donation on at least one occasion over the study period. Statistical analysis showed that the TSP, IgG and IgM levels of new donors who had donated plasma on less than 10 occasions were no more likely to fall below normal than those of old donors. However, new and old donors whose IgG or IgM levels fell below normal at any time during the study had significantly lower levels of the relevant parameter on entry to the study. Followed longitudinally, IgG and IgM levels in old and new donors tended to fall, although levels fluctuated throughout the study. Statistical analysis failed to show any correlation between TSP levels and IgG or IgM levels. These parameters did not correlate significantly with the number of previous plasmaphereses, donor weight, volume collected or history of infection. This study highlighted the need for regular, specific quantitation of IgG and IgM levels as well as TSP in regular plasmapheresis donors. The frequency of testing is yet to be determined, in view of the high materials and labour costs of such a programme.  相似文献   
6.
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   
7.
8.
The range of musculoskeletal disorders encountered in primary care settings is broad, extending from simple injuries to complex chronic diseases. Assessment, management, referral, and pharmacologic intervention for many of these conditions may fall to certified nurse-midwives who increasingly are assuming primary care responsibilities.  相似文献   
9.
10.
The purpose of this study was to determine masticatory and functional forces in three axes on mandibular implants supporting overdentures. Five edentulous test subjects were selected, each having two mandibular implants. Three-dimensional piezoelectric force transducers were mounted on the two-part ITI Bonefit implants and rigidly connected to the denture. Forces in vertical, lateromedial, and anteroposterior directions were measured by means of electrostatic plotter records. The test modalities were light tapping, grinding, maximal occlusal force, and chewing test food. Results showed that the five subjects developed similar stress patterns but quantitatively different occlusal and chewing forces. In all but one subject, reduced maximal occlusal force was found compared to dentate subjects and edentulous subjects with fixed partial prostheses supported by implants. The recordings of chewing cycles when eating test food resulted in very regular rhythmic strokes, similar to those of dentate subjects but with slightly reduced speed. All stress patterns showed that occlusal and chewing forces were mainly directed in vertical, medial, and anterior dimensions. The dominating component was vertical.  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