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   562篇
  免费   24篇
  国内免费   39篇
耳鼻咽喉   7篇
儿科学   39篇
基础医学   25篇
口腔科学   6篇
临床医学   59篇
内科学   121篇
皮肤病学   7篇
神经病学   8篇
特种医学   84篇
外科学   82篇
综合类   12篇
预防医学   20篇
眼科学   3篇
药学   33篇
肿瘤学   119篇
  2023年   2篇
  2022年   2篇
  2021年   6篇
  2020年   6篇
  2019年   5篇
  2018年   8篇
  2017年   7篇
  2016年   2篇
  2015年   9篇
  2014年   8篇
  2013年   18篇
  2012年   28篇
  2011年   47篇
  2010年   36篇
  2009年   15篇
  2008年   14篇
  2007年   43篇
  2006年   23篇
  2005年   23篇
  2004年   17篇
  2003年   12篇
  2002年   21篇
  2001年   23篇
  2000年   12篇
  1999年   6篇
  1998年   20篇
  1997年   23篇
  1996年   26篇
  1995年   12篇
  1994年   22篇
  1993年   16篇
  1992年   14篇
  1991年   10篇
  1990年   10篇
  1989年   14篇
  1988年   7篇
  1987年   7篇
  1986年   10篇
  1985年   10篇
  1984年   5篇
  1983年   5篇
  1982年   6篇
  1981年   6篇
  1980年   1篇
  1978年   1篇
  1977年   3篇
  1976年   1篇
  1975年   1篇
  1930年   1篇
  1929年   1篇
排序方式: 共有625条查询结果,搜索用时 18 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.
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.
We assessed the records of 101 patients with locally advanced transitional cell carcinoma (TCC) of the renal pelvis and ureter treated with postoperative radiation therapy to determine outcome and patterns of failure. Locally advanced disease (i.e., T3–4N0 or N+ disease) was identified in 65 patients. Postoperative radiation was used to treat 86 patients, with a median dose of 35 Gy in 20 fractions over 4 weeks to the tumor bed and regional lymph nodes. There were 15 patients with no residual disease who were offered no further therapy. No patient received postoperative chemotherapy. Prognostic factors were examined using univariate and multivariate analysis, and the patterns of failure were identified after postoperative irradiation. Median follow-up was 9.3 years, during which 76 deaths occurred. The 5-year overall survival was 43% and 10-year survival was 23%. A multivariate analysis identified T3 category, lymph node involvement, and age at diagnosis as significant prognostic factors for survival. Tumor grade was a significant prognostic factor on univariate analysis but not on multivariate analysis. Failure analysis showed that only 36% of patients with locally advanced disease remained relapse free. For this group of patients, distant metastases developed in 53%, and locoregional failured occurred in 35% despite postoperative irradiation. Locoregional failure occurred in 95% of patients with nodal involvement who received postoperative radiation, and 77% of those developed distant relapse. This leads us to conclude that patients with resected locally advanced (T3, T4N0, N+) TCC of the upper urinary tracts have a high risk of relapse and death from disease despite postoperative radiotherapy. Because the main feature of the disease is early distant failure, post-operative chemotherapy is required to improve the outcome for this group of patients.  相似文献   
8.
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   
9.
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   
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