全文获取类型
收费全文 | 698篇 |
免费 | 42篇 |
国内免费 | 2篇 |
专业分类
耳鼻咽喉 | 12篇 |
儿科学 | 24篇 |
妇产科学 | 3篇 |
基础医学 | 53篇 |
口腔科学 | 45篇 |
临床医学 | 64篇 |
内科学 | 86篇 |
皮肤病学 | 8篇 |
神经病学 | 29篇 |
特种医学 | 55篇 |
外国民族医学 | 7篇 |
外科学 | 71篇 |
综合类 | 3篇 |
一般理论 | 1篇 |
预防医学 | 34篇 |
眼科学 | 5篇 |
药学 | 99篇 |
中国医学 | 4篇 |
肿瘤学 | 139篇 |
出版年
2023年 | 6篇 |
2022年 | 12篇 |
2021年 | 16篇 |
2020年 | 16篇 |
2019年 | 18篇 |
2018年 | 15篇 |
2017年 | 14篇 |
2016年 | 24篇 |
2015年 | 22篇 |
2014年 | 30篇 |
2013年 | 52篇 |
2012年 | 63篇 |
2011年 | 52篇 |
2010年 | 23篇 |
2009年 | 27篇 |
2008年 | 34篇 |
2007年 | 46篇 |
2006年 | 26篇 |
2005年 | 23篇 |
2004年 | 12篇 |
2003年 | 21篇 |
2002年 | 13篇 |
2001年 | 12篇 |
2000年 | 15篇 |
1999年 | 6篇 |
1998年 | 3篇 |
1997年 | 2篇 |
1996年 | 7篇 |
1995年 | 4篇 |
1993年 | 1篇 |
1992年 | 9篇 |
1991年 | 21篇 |
1990年 | 7篇 |
1989年 | 15篇 |
1988年 | 11篇 |
1987年 | 18篇 |
1986年 | 10篇 |
1985年 | 3篇 |
1984年 | 6篇 |
1983年 | 6篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1980年 | 4篇 |
1979年 | 4篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1973年 | 2篇 |
1971年 | 1篇 |
1970年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有742条查询结果,搜索用时 15 毫秒
1.
2.
Imidazole and isocytosine-furan derivatives inhibited H2 receptor activity in HGT-1 cells, in accordance with the following relative potencies (IC50 = 2.3 microM cimetidine as reference): SKF 93479 = cimetidine = 100 greater than metiamide = 62 greater than SKF 92408 = 2 greater than SKF 91581 = 0.07). The Schild plot for cimetidine was linear (slope = 0.97) with a pA2 value of 6.72 +/- 0.12 (Ki = 0.18 microM cimetidine), suggesting competitive inhibition. Preincubation of HGT-1 cells for 10 min with H2 antagonists at 2 microM concentration resulted in 90-100% inactivation (SKF 93479 and oxmetidine) and 65% inactivation (ranitidine) which persisted for 30 min, even after a washout period. Accordingly, the kinetics of 2 microM [3H] SKF 93479 binding to HGT-1 cells revealed a half-time for association of 10 min and a dissociation half-time of 120 min. There was a good correlation between the kinetics and relative potencies of cimetidine and SKF 93479 in inhibiting H2 receptor activity in purified plasma membranes (40 nM) as well as in intact HGT-1 cells preincubated for 2 hr with SKF 93479 before histamine addition (45 nM). Chronic treatment of HGT-1 cells for 6 days with 2 microM SKF 93479 specifically blocked H2 receptor activity since cyclic AMP generation induced by other hormones and agents such as VIP, glucagon, GIP and sodium fluoride was unaltered. In contrast, short term and chronic treatment by cimetidine was readily reversible. The isocytosine-furan derivative SKF 93479 differs from the imidazole analogue cimetidine by its apparent irreversible action, due to the slow onset of association from HGT-1 cells. The isocytosine ring in SKF 93479 and oxmetidine seems to play a preponderant role in their apparent long-lasting, irreversible actions. 相似文献
3.
Postoperative radiation therapy in the management of lung cancer 总被引:1,自引:0,他引:1
Postoperative radiation therapy for lung cancer is still controversial. In a 9-year period, 69 patients with non-oat-cell carcinoma of the lung (16% stage I, 26% stage II, and 58% stage III) received such therapy. The radiation dose was less than 5,000 cGy in 42 patients, 5,000-5,900 cGy in 16, and 6,000 cGy or more in 11; follow-up ranged from 24 to 64 months. Actuarial survival at 2 and 4 years was 50% and 16%, respectively, for squamous cell carcinoma, and 40% and 26% for adenocarcinoma. The 5-year survival for stages I, II, and III cancer was 29%, 17%, and 19%, respectively. Histologic findings and type of surgery did not affect survival, but the radiation dose apparently did. The 3-year survival for patients who received less than 6,000 cGy was 35%, compared with 73% for patients who received higher doses. In eight patients, treatment failed within the irradiated volume: all had received doses of less than 6,000 cGy, and the volume in three was judged to be inadequate. 相似文献
4.
A case with severe malabsorption of fat soluble vitamins is described. The malabsorption developed after an intestinal bypass operation due to morbid obesity. Night blindness occurred as the first symptom of vitamin A deficiency. The cone visual sensory threshold was elevated about one log unit and the rod threshold abot two and a half log units. No changes of the a- and b-waves of the electroretinogram (ERG) was observed. However, during the initial phase of very low serum reninol level (0.21 mumol/l) the summed amplitudes of the oscillatory potentials (OPs) were lower. After parenteral therapy with vitamin A the night blindness disappeared and the dark-adapted rod and cone threshold sensitivity recovered to normal. However, the time-course of rod adaptation first reached normal levels after 5 months. The amplitudes of the OPs of the ERG response returned to normal when the serum retinol level had increased close to normal. Serum retinol levels of 0.7 mumol/l or higher were always associated with normal or close to normal dark-adapted rod sensitivity. However, a normal serum retinol level (> 0.95 mumol/l) and a normal dark-adapted rod threshold sensitivity were not always associated with a normal time-course of the rod adaptation. It is concluded, that the maintenance dosage of vitamin A must be individualized and that patients who have undergone jejuno-ilea bypass surgery must be carefully monitored for vitamin A deficiency by both serum levels and dark adaptation measurements. 相似文献
5.
Quality assurance problems in clinical hyperthermia and their impact on therapeutic outcome: a Report by the Radiation Therapy Oncology Group 总被引:2,自引:0,他引:2
C A Perez B Gillespie T Pajak N B Hornback B Emami P Rubin 《International journal of radiation oncology, biology, physics》1989,16(3):551-558
Since February 1981, 300 patients with superficial measurable tumors were randomized on an RTOG protocol (81-04) involving fractionated radiation therapy (4.00 Gy twice weekly for a total of 32.00 Gy), either alone or followed immediately by hyperthermia (42.5 degrees C, 60 min). This is a report of 218 eligible patients with single lesions: 107 treated with radiotherapy alone (RT), 111 with radiotherapy plus hyperthermia (RT + HT). Only 56% of the 24 tumors less than 3 cm and 36% of the 53 lesions larger than 3 cm received what was felt to be "adequate" therapy (greater than or equal to 29 Gy and 8 heating sessions). Overall complete response (CR) was observed in 28% of the patients treated with RT, and 32% of the patients receiving RT and heat. Response has been found in previous analyses of this and other RTOG studies to be significantly related to both maximum tumor diameter (less than 3 or greater than or equal to 3 cm) and site/histology (breast/adenocarcinoma, head and neck/squamous, or other site/histologies). In the head and neck tumors less than 3 cm in diameter there was no difference in CR with irradiation alone or combined with hyperthermia (46% vs 43%). However, in the breast, and trunk and extremities a better CR rate was noted with irradiation and heat (55% and 67%) than with irradiation alone (33% and 0). In lesions less than 3 cm treated with irradiation and heat the probability of remaining in response was 80% compared with 15% with irradiation alone. In lesions larger than 3 cm no difference in CR was observed in either treatment group. It has been hypothesized that the response rate is higher in patients with smaller lesions (less than 3 cm) and in breast/chest wall, trunk/extremity lesions because these tumors and anatomical sites are easier to heat adequately. Problems encountered in correlating tumor response with quality of heating include less than optimal heating in larger lesions and the limited ability of current thermometry to accurately represent the temperature distribution in a tumor. Furthermore, differences in equipment and treatment practices among institutions add to the variability in heat administration data collected. In addition, tumor response may be difficult to judge because of short survival of some patients and occasionally rapid tumor regression that may cause necrosis which may be misinterpreted as persistent tumor.(ABSTRACT TRUNCATED AT 400 WORDS) 相似文献
6.
CT-based delineation of lymph node levels and related CTVs in the node-negative neck: DAHANCA, EORTC, GORTEC, NCIC,RTOG consensus guidelines. 总被引:25,自引:0,他引:25
Vincent Grégoire Peter Levendag Kian K Ang Jacques Bernier Marijel Braaksma Volker Budach Cliff Chao Emmanuel Coche Jay S Cooper Guy Cosnard Avraham Eisbruch Samy El-Sayed Bahman Emami Cai Grau Marc Hamoir Nancy Lee Philippe Maingon Karin Muller Hervé Reychler 《Radiotherapy and oncology》2003,69(3):227-236
BACKGROUND AND PURPOSE: The appropriate application of 3-D CRT and IMRT for HNSCC requires a standardization of the procedures for the delineation of the target volumes. Over the past few years, two proposals--the so-called Brussels guidelines from Grégoire et al., and the so-called Rotterdam guidelines from Nowak et al.--emerged from the literature for the delineation of the neck node levels. Detailed examination of these proposals however revealed some important discrepancies. MATERIALS AND METHODS: Within this framework, the Brussels and Rotterdam groups decided to review their guidelines and derive a common set of recommendations for delineation of neck node levels. This proposal was then discussed with representatives of major cooperative groups in Europe (DAHANCA, EORTC, GORTEC) and in North America (NCIC, RTOG), which, after some additional refinements, have endorsed them. The objective of the present article is to present the consensus guidelines for the delineation of the node levels in the node-negative neck. RESULTS AND CONCLUSIONS: First a short discussion of the discrepancies between the previous Brussels and the Rotterdam guidelines is presented. The general philosophy of the consensus guidelines and the methodology used to resolve the various discrepancies are then described. The consensus proposal is then presented and representative CTVs that are consistent with these guidelines are illustrated on CT sections. Last, the limitations of the consensus guidelines are discussed and some concerns about the direct applications of these guidelines to the node-positive neck and the post-operative neck are described. 相似文献
7.
Khoobi M Emami S Dehghan G Foroumadi A Ramazani A Shafiee A 《Archiv der Pharmazie》2011,344(9):588-594
Coumarin and benzothiazole scaffolds can be found in a number of natural or synthetic antioxidants. In an effort to develop a novel radical scavenger and potential antioxidant, a series of coumarin derivatives containing 2‐methylbenzothiazoline motif and related compounds was synthesized and evaluated for their DPPH (1,1‐diphenyl‐2‐picrylhydrazyl) and ABTS?+ (2,2′‐azinobis(3‐ethylbenzothiazoline‐6‐sulfonic acid) radicals scavenging activities. Among them, 7‐hydroxy‐3‐(2‐methyl‐2,3‐dihydrobenzo[d]thiazol‐2‐yl)‐2H‐chromen‐2‐one ( 3e ) has shown a significant free radical scavenging activity. From the structure–activity point of view, it was found that phenolic coumarin ring and benzothiazoline moiety in target compounds may contribute to the scavenging activity against free radicals. 相似文献
8.
Jiangsheng Yu Masaru Ishii Michelle Law John M Woodburn Kiarash Emami Stephen Kadlecek Vahid Vahdat Richard A Guyer Rahim R Rizi 《Magnetic resonance in medicine》2008,59(1):124-131
The dependence of hyperpolarized (HP) (3)He T(1) on local oxygen concentration provides the basis for measuring the partial pressure of oxygen (pO(2)) and oxygen depletion rate (R) in the lungs. Precise measurements of this type are difficult because the oxygen effect manifests itself through a decay of signal, leading to noisy images at the end of the series. The depolarization caused by RF excitation pulses further complicates the problem. It is therefore important to optimize scan parameters, such as measurement timing and flip angle, to obtain accurate and reproducible measurements. This work presents a new single-acquisition technique in conjunction with the multiple regression fitting method for data evaluation. Analytical expressions for the measurement uncertainties are derived. A total of four types of single-acquisition timing schemes are investigated; simulation shows a large uncertainty variation between these schemes (pO(2): 7.5-30.2%; R: 47.4-173.7%). A basic procedure for optimizing scan parameters is then described. A phantom experiment was conducted to verify the simulation results. Repeated in vivo measurements with the optimal scheme in a rabbit experiment showed that average variation of global mean is 6.2% for pO(2) and 12.0% for R, and that the average variation of percentiles (10th, 25th, 50th, 75th, and 90th) is 8.7% for pO(2) and 19.0% for R. 相似文献
9.
Basati Gholam Razavi Amirnader Emami Pakzad Iraj Malayeri Fardin Ali 《Tumour biology》2016,37(2):1781-1788
Tumor Biology - The microRNAs (miRNAs), miR-194 and miR-29b, have been shown to downregulate in colorectal cancer (CRC) and may identify and classify CRC patients as compared with those in control... 相似文献
10.