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   641篇
  免费   33篇
  国内免费   42篇
耳鼻咽喉   4篇
儿科学   34篇
妇产科学   1篇
基础医学   41篇
口腔科学   6篇
临床医学   70篇
内科学   114篇
皮肤病学   6篇
神经病学   28篇
特种医学   89篇
外科学   166篇
综合类   9篇
预防医学   9篇
眼科学   3篇
药学   43篇
肿瘤学   93篇
  2023年   2篇
  2021年   6篇
  2020年   4篇
  2019年   10篇
  2018年   4篇
  2017年   9篇
  2016年   10篇
  2015年   13篇
  2014年   24篇
  2013年   19篇
  2012年   46篇
  2011年   23篇
  2010年   24篇
  2009年   20篇
  2008年   27篇
  2007年   52篇
  2006年   26篇
  2005年   24篇
  2004年   18篇
  2003年   12篇
  2002年   15篇
  2001年   17篇
  2000年   23篇
  1999年   13篇
  1998年   21篇
  1997年   21篇
  1996年   24篇
  1995年   11篇
  1994年   21篇
  1993年   12篇
  1992年   14篇
  1991年   8篇
  1990年   13篇
  1989年   22篇
  1988年   12篇
  1987年   10篇
  1986年   13篇
  1985年   19篇
  1984年   6篇
  1983年   6篇
  1982年   7篇
  1981年   7篇
  1980年   3篇
  1978年   5篇
  1977年   5篇
  1976年   3篇
  1975年   3篇
  1974年   1篇
  1973年   4篇
  1972年   3篇
排序方式: 共有716条查询结果,搜索用时 140 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.
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   
5.
The combination of temozolomide (TEM) and interferon-alpha (IFN-alpha) previously demonstrated a 30% response rate in metastatic melanoma. A single institution, phase II trial evaluating the efficacy of TEM/IFN in patients with advanced renal cell carcinoma (RCC) was conducted. Safety and tumor response were the main outcomes. Eligible patients received 200 mg/m(2)/day TEM orally on days 1-5 every 28 days, with IFN 2.5 million U/m(2)/day subcutaneously (s.c.) three alternate days/week for days 1-15 first cycle, then 5 million U/m(2)/day s.c. 3 alternate days/week throughout each 28-day cycle. Efficacy was evaluated every 8 weeks, and dose-limiting toxicities (DLTs) were treated with dose reductions of the culprit drug. Sixteen patients (ages 37-67) were initially enrolled. Of the 14 evaluable patients, there was one minor response. Best response was stable disease, with 7 patients remaining on study for > or =6 months. Five were alive for more than 2 years, and 2 remain alive at 45 and 50 months after enrollment. DLTs included TEM-induced myelosuppression and IFN-induced fever/chills. Other toxicities were mild to moderate (grades 1-3). The combination of TEM/IFN proved quite tolerable. This regimen appears inactive in terms of response in this population with poor prognosis, but the patients with stable disease > or =6 months remain of interest.  相似文献   
6.
To test the hypothesis that maximal androgen blockade improves the effectiveness of the treatment of prostatic cancer, we conducted a randomized, double-blind trial in patients with disseminated, previously untreated prostate cancer (stage D2). All 603 men received leuprolide, an analogue of gonadotropin-releasing hormone that inhibits the release of gonadotropins, in combination with either placebo or flutamide, a nonsteroidal antiandrogen that inhibits the binding of androgens to the cell nucleus. As compared with the 300 patients receiving leuprolide and placebo, the 303 patients randomly assigned to receive leuprolide and flutamide had a longer progression-free survival (16.5 vs. 13.9 months; P = 0.039) and an increase in the median length of survival (35.6 vs. 28.3 months; P = 0.035). The differences between the treatments were particularly evident for men with minimal disease and good performance status; however, further studies should be conducted in this subgroup. Symptomatic improvement was greatest during the first 12 weeks of the combined androgen blockade, when leuprolide alone often produces a painful flare in the disease. We conclude that in patients with advanced prostate cancer, treatment with leuprolide and flutamide is superior to treatment with leuprolide alone.  相似文献   
7.
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   
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.
Monolayers of dipalmitoyl phosphatidylcholine have been transferred from an air-water interface to single-crystal silicon wafers previously alkylated with octadecyltrichlorosilane. By using synchrotron radiation it has been found possible to observe diffraction by single-crystal regions of these monolayers with negligible background scattering from the solid substrate. In one series of experiments, diffraction signals at Bragg spacings of 0.4247 ± 0.0002 nm and 0.4253 ± 0.0002 nm were observed. The supported phospholipid monolayer crystals show remarkably high in-plane order: the positional coherence length is at least 500 nm and the orientational order is better than 0.01°. Preliminary temperature scans were carried out. The data reveal the existence of a phase transition at about 65°C.  相似文献   
10.
Summary In 11 mongrel dogs both kidneys have been subjected to a 2 h ischaemic period. One kidney was cooled by perfusing the renal artery at 4°C while the contralateral normothermic kidney was clamped for 2 h. Studying the renal blood flow using the Xenon wash out technique, sequential renal scanning and angiography, marked differences between hypo- and normothermic ischaemia kidneys were observed. One or two hours following hypothermic perfusion a marked decrease of blood flow in the first compartment and vasoconstriction was evident, while within this period following normothermic ischaemia an enhanced renal blood flow was observed. After 24 h renal blood flow and renal function tested by 131I-Hippuran clearance returned to normal values. Angiographic studies corresponded to the preoperative findings. In contrast, normothermic ischaemia kidneys showed a decreased renal blood flow, impairment of kidney function in isotope studies and pathological angiographic changes.Supported by Deutsche Forschungsgemeinschaft  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