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   394篇
  免费   23篇
  国内免费   39篇
耳鼻咽喉   3篇
儿科学   51篇
妇产科学   2篇
基础医学   25篇
口腔科学   10篇
临床医学   64篇
内科学   76篇
皮肤病学   5篇
神经病学   6篇
特种医学   80篇
外科学   53篇
综合类   8篇
预防医学   18篇
眼科学   4篇
药学   39篇
肿瘤学   12篇
  2023年   2篇
  2021年   3篇
  2020年   6篇
  2019年   6篇
  2018年   4篇
  2017年   5篇
  2015年   9篇
  2014年   12篇
  2013年   15篇
  2012年   15篇
  2011年   10篇
  2010年   18篇
  2009年   11篇
  2008年   10篇
  2007年   32篇
  2006年   13篇
  2005年   13篇
  2004年   15篇
  2003年   7篇
  2002年   7篇
  2001年   9篇
  2000年   10篇
  1999年   6篇
  1998年   19篇
  1997年   20篇
  1996年   24篇
  1995年   11篇
  1994年   20篇
  1993年   10篇
  1992年   11篇
  1991年   6篇
  1990年   7篇
  1989年   13篇
  1988年   7篇
  1987年   6篇
  1986年   8篇
  1985年   10篇
  1984年   6篇
  1983年   5篇
  1982年   6篇
  1981年   7篇
  1980年   2篇
  1979年   2篇
  1977年   3篇
  1976年   2篇
  1975年   2篇
  1969年   2篇
  1935年   1篇
  1934年   1篇
  1931年   1篇
排序方式: 共有456条查询结果,搜索用时 279 毫秒
1.
Beckmann  CF; Roth  RA; Luedke  MD 《Radiology》1986,159(3):643-645
In 44 patients with one or more calculi in the upper two-thirds of the ureter, single-stage percutaneous nephrolithotomy was performed through a middle or upper calyceal nephrostomy after cystoscopic placement of an occlusion balloon catheter distal to the calculus; in 42, the procedure was successful. The occlusion balloon catheter permitted retrograde opacification of all systems for enhanced renal puncture. In the last 30 patients an attempt was made either to push the calculus upward mechanically or to flush it upward into the renal pelvis with carbon dioxide or dilute contrast material. This was successful in 24 of these patients. Prior overnight occlusion of the ureter by means of ureteral dilatation further facilitates dislodgment of the calculus, which was successful in 12 of 13 patients.  相似文献   
2.
This study evaluated factors influencing fracture (n = 197) and osteotomy (n = 200) healing in children with moderate to severe OI. Pamidronate treatment was associated with delayed healing after osteotomy, but not after fracture. The data suggest that both pamidronate and mechanical factors influence bone healing in this cohort. INTRODUCTION: Intravenous pamidronate is widely used to treat children with moderate to severe osteogenesis imperfecta (OI). However, the effect of this treatment on bone healing is not well characterized. We therefore retrospectively analyzed the healing of lower limb fractures and osteotomies in children with moderate to severe OI, both before and after the start of pamidronate treatment. MATERIALS AND METHODS: Bone healing was evaluated on standard radiographs after 197 lower limb fractures (132 femur and 65 tibia) in 82 patients (age at fracture, 0.0-19.9 years) and 200 intramedullary rodding procedures in 79 patients (age at surgery, 1.2-19.8 years). Delayed healing was diagnosed when a fracture or osteotomy line was at least partially visible 12 months after the event. RESULTS: Delayed fracture healing was observed more frequently during than before pamidronate treatment. However, the effect of pamidronate was no longer significant when age differences were taken into account (odds ratio [OR], 1.76; 95% CI, 0.61-5.10). Better mobility status was a strong independent predictor of delayed healing after fractures that occurred during pamidronate treatment. After osteotomies, delayed healing was more frequent when pamidronate had been started before surgery (OR, 7.29; 95% CI, 2.62-20.3), and this effect persisted after adjustment for multiple confounders. During pamidronate treatment, older age (OR per year of age, 1.25; 95% CI, 1.06-1.47) and osteotomy of the tibia (OR, 3.51; 95% CI, 1.57-7.82) were independent predictors of delayed healing. CONCLUSIONS: This study suggests that pamidronate therapy is associated with delayed healing of osteotomy sites after intramedullary rodding procedures. Better mobility status, but not pamidronate treatment, seems to be predictive of delayed healing after fractures.  相似文献   
3.
4.
5.
Elevated blood pressure is an important risk factor for renal-, cerebro- and cardiovascular diseases. We used an efficient discordant sib-pair ascertainment scheme to investigate the impact of the distal end of the long arm of human chromosome 5 (chromosomal region 5q31.1-qter) containing genes for the alpha1B and beta2 adrenergic receptors and the dopamine receptor type 1A on variation of systolic blood pressure in young Caucasians. We measured eight highly polymorphic markers spanning this positional candidate gene-rich region in 427 individuals from 55 three-generation pedigrees containing 69 discordant sibling pairs, and calculated multipoint identity by descent (MIBD) probabilities. The results of genetic linkage and association tests indicate that the region between markers D5S2093 and D5S462 is significantly linked to one or more polymorphic genes influencing interindividual variation in systolic blood pressure levels. Since the alpha1B adrenergic receptor and dopamine receptor type 1A genes are located close to these markers, these data suggest that genetic variation in one or both of these G protein-coupled receptors, which participate in the control of vascular tone, plays an important role in influencing interindividual variation in systolic blood pressure levels.   相似文献   
6.
Acute porphyria is rare in orientals. We describe a Chinese woman with recurrent generalised tonic-clonic seizures and abdominal pain. Genomic DNA studies identified a heterozygous base substitution from guanine to adenine at nucleotide position 503, resulting in substitution of arginine by histidine at position 168 of the protein (R168H). This genetic abnormality is similar to the mutation reported in Caucasians with variegate porphyria. To the best of our knowledge, this is the first report in the English literature a Chinese patient with variegate porphyria with an identifiable mutation. A brief review of porphyria is presented.  相似文献   
7.
Inflamed fibronectin: an altered fibronectin enhances neutrophil adhesion   总被引:4,自引:0,他引:4  
Vercellotti  GM; McCarthy  J; Furcht  LT; Jacob  HS; Moldow  CF 《Blood》1983,62(5):1063-1069
Recent investigations have emphasized the role of activated granulocytes in mediating vascular endothelial injury in the pathogenesis of shock lung. In vitro studies have indicated that tight adherence of the neutrophil to the endothelium is crucial for the development of cellular injury. Fibronectin is critical to cell-to- substratum and cell-to-cell interactions. Since fibronectin resides in plasma, on endothelial cell surfaces and is secreted into cell matrices, the adhesive properties of fibronectin must be modulated, lest universal cell agglomeration occur, yet be enhanced when cell attachment is appropriate. In these studies, treatment of fibronectin- coated surfaces with neutrophil release products increased the adhesion of activated neutrophils. Similarly, endothelial cells treated with neutrophil release products become a more adherent substrate for neutrophils. This enhanced adherence generated by treatment of fibronectin with neutrophil supernatants is inhibitable by heat and the lysosomal proteinase inhibitor, pepstatin-A. Neutrophil release products cause proteolytic fragmentation of fibronectin and enhanced fibronectin immunofluorescence on endothelial cells. In addition, neutrophils are more injurious to endothelial cells that have been pretreated with neutrophil release products. Neutrophils may enhance their own adherence to endothelial cells by altering fibronectin, and this altered, or "inflamed," fibronectin may serve as an amplifier of inflammation.  相似文献   
8.
The variation in colorectal cancer (CRC) incidence worldwide strongly suggests a role for dietary influences. Based on epidemiological data, protective effects of vegetables and fruit intake on CRC are widely claimed, while other data indicate a possible increased CRC risk from (higher) dietary fat intake. Therefore, we have investigated single and interactive effects of dietary fat and a vegetable-fruit mixture (VFM) in the ApcMin mouse, a mouse model for multiple intestinal neoplasia. In this study, four different diets (A-D) were compared, which were either low in fat (20% energy diets A/B) or high in fat (40% energy diets C/D). In addition, 19.5% (wt/wt) of the carbohydrates in diets B and D were replaced by a freeze-dried VFM. The diets were balanced so that they only differed among each other in fat/carbohydrate content and the presence of specific plant-constituents. Because the initiation of intestinal tumors in ApcMin mice occurs relatively early in life, exposure to the diets was started in utero. Without the addition of VFM, mice maintained at a high-fat diet did not develop significantly higher numbers of small or large intestinal adenomas than mice maintained at a low-fat diet. VFM added to a low-fat diet significantly lowered multiplicity of small intestinal polyps (from 16.2 to 10.2/mouse, 15 animals/group), but not of colon tumors in male ApcMin mice only. Strikingly, addition of VFM to female mice maintained on a low-fat diet and to both sexes maintained on a high-fat diet significantly enhanced intestinal polyp multiplicity (from 16.5 to 26.7 polyps/mouse). In conclusion, our results indicate that neither a lower fat intake nor consumption of VFM included in a high-fat diet decreases the development of polyps in mice genetically predisposed to intestinal tumor development.   相似文献   
9.
BACKGROUND: Early implantation of centrifugal devices in patients with postcardiotomy cardiogenic shock may provide a bridge to recovery and allow subsequent long-term survival. METHODS: Since January 1989, 62 patients were supported with centrifugal pumps because of failure to wean from cardiopulmonary bypass. Indications were postcardiotomy cardiogenic shock (PCCS) (n = 60), bridge to cardiac retransplantation (n = 1), and right ventricular failure (n = 1). Patients' ages ranged from 23 to 78 years; 40 were men (65%), and 22 were women (35%). Twenty-two patients (35%) had a left ventricular assist device; 9 patients (15%) had a right ventricular assist device; and 31 patients (50%) had a biventricular assist device. Length of support ranged from 1 day to 19 days. RESULTS: Forty-two patients (68%) were weaned successfully; 27 patients survived to discharge (44%). Complications included bleeding (n = 41, 66%), renal failure (n = 28, 45%), and respiratory failure (n = 26, 42%). Currently, 23 patients survived 10 or more years (n = 1), 6 to 10 years (n = 7), 1 to 5 years (n = 10), and less than 1 year (n = 5). CONCLUSIONS: Centrifugal pumps are available, easy to use, and relatively inexpensive. Our experience justifies their continued use as a bridge to recovery for patients with postcardiotomy cardiogenic shock, despite the availability and increasing use of more expensive devices.  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