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   142篇
  免费   13篇
耳鼻咽喉   1篇
儿科学   2篇
妇产科学   2篇
基础医学   21篇
口腔科学   2篇
临床医学   12篇
内科学   9篇
皮肤病学   5篇
神经病学   1篇
特种医学   5篇
外科学   44篇
综合类   12篇
预防医学   3篇
药学   5篇
肿瘤学   31篇
  2022年   1篇
  2020年   2篇
  2019年   2篇
  2018年   4篇
  2017年   4篇
  2016年   4篇
  2015年   3篇
  2014年   10篇
  2013年   13篇
  2012年   19篇
  2011年   10篇
  2010年   6篇
  2009年   2篇
  2008年   4篇
  2007年   4篇
  2006年   2篇
  2005年   4篇
  2004年   3篇
  2003年   5篇
  2002年   1篇
  2001年   2篇
  2000年   2篇
  1999年   2篇
  1998年   3篇
  1997年   3篇
  1995年   2篇
  1994年   3篇
  1993年   2篇
  1992年   3篇
  1991年   1篇
  1990年   5篇
  1989年   7篇
  1988年   2篇
  1987年   3篇
  1986年   5篇
  1985年   3篇
  1981年   1篇
  1977年   2篇
  1975年   1篇
排序方式: 共有155条查询结果,搜索用时 15 毫秒
1.
An unsymmetrical diamine monomer 4‐(p‐aminophenoxy)‐3‐trifluoromethyl‐4′‐aminobiphenyl has been synthesized successfully. This monomer leads to the synthesis of different novel poly(ether imide)s when reacted with different dianhydrides like pyromellatic dianhydride (PMDA), benzophenone tetracarboxylic acid dianhydride (BTDA), 2,2‐bis(3,4‐dicarboxyphenyl) hexafluoropropane (6FDA), and oxy diphthalic anhydride (ODA). The poly(ether imide) prepared from this monomer on reaction with 6FDA is soluble in several organic solvents such as N‐methylpyrolidinone (NMP), dimethylformamide (DMF), N,N‐dimethylacetamide (DMAc), tetrahydrofuran (THF), and CHCl3. The poly(ether imide)s prepared from BTDA and ODA are soluble in NMP, DMF, and DMAc but not in THF or CHCl3, whereas the polymer prepared from PMDA is soluble only in NMP. The water uptake value for these poly(ether imide) films is very low (0.2–0.5%), and exhibited low dielectric constants (2.81 at 1 MHz). The polymers exhibited high thermal stability up to 532 °C in air for 5% weight loss, and high glass transition temperatures up to 288 °C. The polymer exhibited high tensile strength up to 135 MPa, modulus 3.2 GPa, and elongation at break up to 25%, depending on the exact polymer structure.

The structure of the poly(ether imide) synthesised from 4‐(p‐aminophenoxy)‐3‐trifluoromethyl‐4′‐aminobiphenyl and 2,2‐bis(3,4‐dicarboxyphenyl) hexafluoropropane. This polymer was soluble in many organic solvents.  相似文献   

2.
Retinoid inhibition of breast carcinoma growth correlates with the estrogen receptor (ER) positivity and elevated retinoic acid nuclear receptor (RARalpha) mRNA levels. We therefore examined retinoid nuclear receptor mRNA levels in patient breast carcinoma biopsy specimens to determine if such a correlation exists between ER positivity and RARalpha mRNA levels. We have now shown that RARalpha mRNA levels are significantly higher in ER positive samples. RARgamma mRNA is expressed at relatively high levels in a majority of the tumor samples independent of the ER-status while RARbeta mRNA was expressed at low levels in only one tumor sample. We also found high RXRalpha mRNA levels in all of the tumor samples examined while RXRgamma mRNA could not be detected. Our study demonstrates that RARalpha mRNA levels are either low or absent in ER-negative patient samples and that RARalpha levels may serve as a potential marker to determine patient responsiveness to RA therapy.  相似文献   
3.
Plasmodium vivax infection is increasingly a major public health burden and the second most frequent human malaria. Higher levels of clinical severity and chloroquine resistance are major factors responsible for such increases. Malarial glomerular injury is uncommon and mainly observed in Plasmodium malariae-infected patients. Occasionally, transient immune complex-mediated glomerulonephritis is associated with Plasmodium falciparum infection. Coexistent crescentic glomerulonephritis and vivax malaria have not previously been reported. We report a fatal case of P. vivax malaria, who presented with acute renal failure. P. vivax monoinfection status was diagnosed with peripheral blood smear and rapid antigen test. Further evaluation for renal failure related to systemic illness and immunological markers were inconclusive. He was treated with antimalarial drugs, hemodialysis, and supportive therapy. Renal biopsy performed for nonrecovering renal failure reveled crescentic glomerulonephritis. This case highlights the need to thoroughly search for malaria-associated crescentic glomerulonephritis using renal biopsy after nonrecovering renal failure.  相似文献   
4.
Schiffer  CA; Sanel  FT; Young  VB; Aisner  J 《Blood》1977,50(2):213-225
The effects of the cationic anesthetic agents tetracaine and lidocaine on granulocyte function, morphology, and adherence to nylon fibers were studied in an attempt to improve current methods of granulocyte collection by filtration leukapheresis (FL). When dissolved in acid- citrate-dextrose (ACD) plasma, these drugs significantly increased granulocyte elution from the fibers in a dose-related fashion. Granulocytes exposed to tetracaine and lidocaine remained more than 95% viable, retained normal bactericidal capacity after the drugs were washed from the cells, and had preserved membrane integrity, as evidenced by the normal ultrastructural appearance of tetracaine- exposed cells and an absence of leakage of lysozyme or lactic dehydrogenase. Granulocytes eluted with the anesthetic agents were rounded in shape with a reduction in the number of filopodial cytoplasmic projections and a relative absence of cytoplasmic vacuolization when compared to granulocytes eluted with ACD plasma alone. Dose-related inhibition of phagocytosis and adherence, which was largely reversible after washing the granulocytes, was noted. Greater than 95% of the lidocaine could be removed from the eluate with a single centrifugation and resuspension, indicating that granulocytes prepared by FL with anesthetic-enhanced elution could be potentially transfusable.  相似文献   
5.
We have investigated the role of platelets in regulating the hemostatic and vasomotor properties of vascular smooth muscle. Experiments were performed to examine the effect of the releasate from activated platelets on the production of nitric oxide from interleukin-1 beta (IL- 1 beta)-treated cultured rat aortic smooth muscle cells. Treatment of vascular smooth muscle cells with IL-1 beta resulted in significant accumulation of nitrite in the culture media and in marked elevation of intracellular cyclic guanosine monophosphate (GMP) levels. The releasate from collagen-aggregated platelets blocked the IL-1 beta- mediated production of nitrite and the accumulation of cyclic GMP in smooth muscle cells in a platelet number-dependent manner. In functional assays, the perfusates from columns containing IL-1 beta- treated smooth muscle cells relaxed detector blood vessels without endothelium and the addition of IL-1 beta-treated smooth muscle cells to suspensions of platelets inhibited their thrombin-induced aggregation. The simultaneous treatment of smooth muscle cells with IL- 1 beta and the platelet releasate abolished both the vasorelaxing activities of the perfusates and the inhibition of platelet aggregation. Platelet releasates treated with a neutralizing antibody to platelet-derived growth factor (PDGF) failed to block IL-1 beta- induced nitric oxide production by the smooth muscle cells, as measured by both biochemical and functional assays. The platelet releasate from a patient with gray platelet syndrome likewise failed to block IL-1 beta-induced nitrite release by smooth muscle cells. These results demonstrate that platelets downregulate the production of nitric oxide by IL-1 beta-treated vascular smooth muscle cells through the release of PDGF. This effect may represent a novel mechanism by which platelets regulate vasomotor tone and thrombus formation at sites of vascular injury.  相似文献   
6.
Laparoscopic kidney transplantation (LKT) is well accepted modality of treatment for ESRD patients at our center. Usually, the kidney is inserted through small Pfannenstiel incision. With the permission of the Internal Review Board, we carried out LKT in eight female recipients following insertion of the kidney through the vagina. The kidney was procured by the retroperitoneoscopic approach. Antibiotic prophylaxis was given. All cases were carried out successfully with immediate graft function and 100% graft and patient survival at 1 year of follow‐up. Estimated glomerular filtration rate at 1 month and 1 year was similar to eight randomly selected female recipients who underwent open kidney transplantation (OKT). No analgesia was required in seven out of eight patients after the 3rd postoperative day. In summary, vaginal insertion of kidney and LKT is safe and feasible in a selected group of patients. It is associated with better analgesia and has similar allograft function as compare to OKT.  相似文献   
7.
Because access to transplantation with HLA‐desensitization protocols and ABO incompatible transplantation is very limited due to high costs and increased risk of infections from more intense immunosuppression, kidney paired donation (KPD) promises hope to a growing number of end‐stage renal disease (ESRD) patient in India. We present a government and institutional ethical review board approved study of 56 ESRD patients [25 two‐way and 2 three‐way pairs] who consented to participate in KPD transplantation at our center in 2013, performed to avoid blood group incompatibility (n = 52) or positive cross‐match (n = 4). All patients had anatomic, functional, and immunologically comparable donors. The waiting time in KPD was short as compared to deceased donor transplantation. Laparoscopic donor nephrectomy was performed in 54 donors. Donor relationships were spousal (n = 40), parental (n = 13), others (n = 3), with median HLA match of 1. Graft survival was 97.5%. Three patients died with functioning graft. 16% had biopsy‐proven acute rejection. Mean serum creatinine was 1.2 mg/dl at 0.73 ± 0.32 months follow‐up. KPD is a viable, legal, and rapidly growing modality for facilitating LDRT for patients who are incompatible with their healthy, willing living donor. To our knowledge, this is the largest single‐center report from India.  相似文献   
8.
A study was made of acetylcholine concentration and of the acetylcholinesterase activity in the thyroid gland tissue, as well as of the serum cholinesterase activity in the toxic goiter. This disease was accompanied by an elevation of the acetylcholine concentration and a fall of the eacetylcholinesterase activity. As to serum cholinesterase--it changed but little in this disease.  相似文献   
9.
Malignant papillary cystic tumor of the pancreas.   总被引:8,自引:0,他引:8  
An example of the rare papillary cystic tumor of the pancreas was diagnosed cytologically by aspiration of the primary neoplasm. Subsequently, it metastasized, proving its low-grade malignant behavior. Diagnostic cytomorphologic features included abundant straight and branched papillary tissue fragments, and uniform, pale nuclei with folds or grooves. Although the primary tumor had a typical histologic appearance, metastases demonstrated increased nuclear pleomorphism and hyperchromasia, bizarre tumor giant cells, and an increased mitotic rate. Vimentin was diffusely positive, whereas neuron-specific enolase and somatostatin were focally and weakly reactive. Neurosecretory and zymogen granules were absent ultrastructurally. By flow cytometric study, the tumor was aneuploid (DNA Index = 1.3).  相似文献   
10.
The histologic separation of keratoacanthomas (KA) and well-differentiated squamous cell carcinoma (WDSCC) using established criteria may present a diagnostic dilemma in the individual case. The authors questioned whether the DNA index (DI) and/or the proliferative index (PI), as shown by flow cytometry (FCM) might assist in this differential diagnosis. Thirty-six well-differentiated squamous cell lesions of skin were independently classified as either WDSCC or KA by a panel of three pathologists. Six poorly differentiated squamous cell carcinomas (PDSCC) also were included in this study. Sections from paraffin blocks were prepared by standard techniques and analyzed by FCM. Mean DI values were: KA 0.96%, WDSCC 0.99%, and PDSCC 0.88%. The differences in the mean DIs were not statistically significant. Mean PI values were as follows: KA 16.7%, WDSCC 14.8%, and PDSCC 20.2%. Differences were not statistically significant. The authors conclude that the FCM measurements of DI and PI do not help in separating KA and WDSCC of skin.  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