全文获取类型
收费全文 | 13993篇 |
免费 | 1122篇 |
国内免费 | 60篇 |
专业分类
耳鼻咽喉 | 123篇 |
儿科学 | 340篇 |
妇产科学 | 338篇 |
基础医学 | 1970篇 |
口腔科学 | 362篇 |
临床医学 | 1499篇 |
内科学 | 2955篇 |
皮肤病学 | 252篇 |
神经病学 | 1027篇 |
特种医学 | 731篇 |
外国民族医学 | 17篇 |
外科学 | 1824篇 |
综合类 | 143篇 |
一般理论 | 6篇 |
预防医学 | 1308篇 |
眼科学 | 177篇 |
药学 | 931篇 |
中国医学 | 20篇 |
肿瘤学 | 1152篇 |
出版年
2021年 | 170篇 |
2020年 | 128篇 |
2019年 | 193篇 |
2018年 | 254篇 |
2017年 | 158篇 |
2016年 | 237篇 |
2015年 | 257篇 |
2014年 | 338篇 |
2013年 | 457篇 |
2012年 | 625篇 |
2011年 | 613篇 |
2010年 | 363篇 |
2009年 | 368篇 |
2008年 | 585篇 |
2007年 | 591篇 |
2006年 | 583篇 |
2005年 | 561篇 |
2004年 | 543篇 |
2003年 | 552篇 |
2002年 | 525篇 |
2001年 | 512篇 |
2000年 | 547篇 |
1999年 | 490篇 |
1998年 | 212篇 |
1997年 | 174篇 |
1996年 | 163篇 |
1995年 | 146篇 |
1994年 | 125篇 |
1993年 | 128篇 |
1992年 | 361篇 |
1991年 | 309篇 |
1990年 | 296篇 |
1989年 | 271篇 |
1988年 | 282篇 |
1987年 | 243篇 |
1986年 | 269篇 |
1985年 | 243篇 |
1984年 | 189篇 |
1983年 | 172篇 |
1982年 | 99篇 |
1981年 | 100篇 |
1980年 | 104篇 |
1979年 | 154篇 |
1978年 | 116篇 |
1977年 | 103篇 |
1976年 | 81篇 |
1975年 | 93篇 |
1974年 | 105篇 |
1973年 | 116篇 |
1971年 | 86篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
van Halteren HK Peters HM van Krieken JH Coebergh JW Roumen RM van der Worp E Wagener JT Vreugdenhil G 《Cancer》2001,91(9):1752-1757
BACKGROUND: The benefit of adjuvant chemotherapy appears to be limited for patients with Astler Coller B1/B2 colorectal carcinoma but may be better in a subgroup of patients with a high recurrence risk. In the current case-control analysis, the authors evaluated whether patients with a high risk of hematogenous metastasis could be identified by means of a thorough histologic and immunohistochemical examination of the resection specimens. METHODS: A database was built for all patients treated in a general teaching hospital for colorectal carcinoma between 1985 and 1995. From this database, all patients with an Astler Coller B1 or B2 tumor who subsequently had developed hematogenous metastases were taken as cases. For each case, three matched controls (age, Astler Coller, year of diagnosis) without metachronous metastases were selected. The resection specimens of cases and controls were blindly examined by two observers for the following: World Health Organization (WHO) classification; differentiation grade; growth pattern; lymphocytic, fibroblastic, and eosinophilic reaction; angioinvasion; number of lymph nodes examined; expression of E-cadherin, vascular endothelial growth factor and thymidine phosphorylase (TP); P53; microvessel density. RESULTS: Twenty-two cases and 65 controls were included in the analysis. Tumor growth pattern and tumor TP expression both independently contributed to recurrence risk. With these 2 variables, 4 subgroups could be identified with a recurrence risk ranging from 0% to 42%. CONCLUSIONS: Tumor growth pattern and degree of TP expression both appear to be related to the recurrence risk. Prospective trials should point out whether these variables can be implemented in the decision making concerning adjuvant chemotherapy. 相似文献
992.
Schallreuter KU Moore J Wood JM Beazley WD Peters EM Marles LK Behrens-Williams SC Dummer R Blau N Thöny B 《The Journal of investigative dermatology》2001,116(1):167-174
It has been shown in vivo that patients with the depigmentation disorder vitiligo accumulate hydrogen peroxide (H(2)O(2)) accompanied by low catalase levels and high concentrations of 6- and 7-biopterin in their epidermis. Earlier it was demonstrated that epidermal 4a-OH-tetrahydrobiopterin dehydratase, an important enzyme in the recycling process of 6(R)-L-erythro 5,6,7,8 tetrahydrobiopterin (6BH(4)), has extremely low activities in these patients concomitant with a build-up of the abiogenic 7-isomer (7BH(4)), leading to competitive inhibition of epidermal phenylalanine hydroxylase. A topical substitution for the impaired epidermal catalase with a pseudocatalase effectively removes epidermal H(2)O(2), yielding a recovery of epidermal 4a-OH-tetrahydrobiopterin dehydratase activities and physiologic 7BH(4) levels in association with successful repigmentation demonstrating recovery of the 6BH(4) recycling process. Examination of recombinant enzyme activities, together with 4a-OH-tetrahydrobiopterin dehydratase expression in the epidermis of untreated patients, identifies H(2)O(2)-induced inactivation of this enzyme. These results are in agreement with analysis of genomic DNA from these patients yielding only wild-type sequences for 4a-OH-tetrahydrobiopterin dehydratase and therefore ruling out the previously suspected involvement of this gene. Furthermore, our data show for the first time direct H(2)O(2) inactivation of the important 6BH(4) recycling process. Based on this observation, we suggest that H(2)O(2) derived from various sources could be a general mechanism in the regulation of all 6BH(4)-dependent processes. 相似文献
993.
994.
Peters JL Fairney A Kyd P Patel A Rogers S Webster JJ Vale JA Witherow RO 《Prostate cancer and prostatic diseases》2001,4(3):161-166
Hypogonadism is a recognised cause of osteoporosis in men. When patients with advanced prostate cancer are treated with luteinising hormone releasing hormone (LHRH) agonist analogues their circulating testosterone levels decline and these patients may develop fractures.We have undertaken a cross-sectional study on a cohort of patients treated with goserelin (n=41) and compared their bone density and bone turnover with patients with prostate cancer not on goserelin and elderly patients living in the community.There was no difference in bone density between the patients on treatment and those living in the community and there was a similar incidence of osteoporosis (50 and 42%, respectively). The bone marker measurements were higher in the treated patients: urine N-telopeptide (NTX) 80.1 (9) (mean (s.e.)) BCE/mmol, compared to 30.1 (2.9), P<0.001 in elderly patients; and bone alkaline phosphatase 41.9 (6.1) u/l in treated patients and 20.7 (1.5) in untreated prostate cancer patients, P<0.002. Patients on treatment with radionuclide scan evidence of metastases did not have higher bone marker values than those with negative scans.As increased bone turnover and low bone density are associated with enhanced risk of osteoporotic fractures, we suggest that patients on LHRH agonist analogues should receive advice and possibly anti-bone resorptive treatment with bisphosphonates to prevent further bone loss and fractures.Prostate Cancer and Prostatic Diseases (2001) 4, 161-166. 相似文献
995.
996.
Lord RV Tsai PI Danenberg KD Peters JH Demeester TR Tsao-Wei DD Groshen S Salonga D Park JM Crookes PF Kiyabu M Chandrasoma P Danenberg PV 《Surgery》2001,129(3):267-276
BACKGROUND: Expression levels of the retinoic acid receptors (RAR-alpha, RAR-beta, and RAR-gamma) are significantly different in neoplastic tissues compared with non-neoplastic tissues for some tumors. This study investigated whether retinoic acid receptor messenger RNA (mRNA) expression levels are altered in Barrett's esophagus and Barrett's adenocarcinoma tissues. METHODS: Relative mRNA expression levels of the RARs were quantified by using the ABI 7700 Sequence Detector (Taqman) system in Barrett's intestinal metaplasia (n = 15), dysplasia (n = 6), adenocarcinoma (n = 17), and matching normal esophagus tissues (n = 36). RESULTS: RAR-alpha expression was significantly increased, and RAR-gamma expression was significantly decreased, at higher stages in the Barrett's sequence. There was almost complete loss of RAR-gamma expression (relative expression level < or = 1) in a majority (70%) of the dysplasia and adenocarcinoma tissues. There were significant differences in RAR-alpha and RAR-gamma expression in histopathologically normal tissues in patients with cancer versus patients without cancer. RAR-beta expression levels were significantly elevated in adenocarcinoma versus normal esophagus tissues. The RAR expression profile was similar for cancers arising within the esophagus and for cancers arising at the gastroesophageal junction. CONCLUSIONS: RAR mRNA expression levels are significantly different in Barrett's tissues compared with normal esophagus tissues, and these levels are significantly different in Barrett's dysplasia and adenocarcinoma tissues compared with nondysplastic tissues. These results suggest that RAR mRNA levels may be useful biomarkers for this disease and that gastroesophageal junction adenocarcinomas are genetically similar to esophageal adenocarcinomas. These results also suggest that a cancer field is present in the esophagus in patients with cancer and that genetic alterations can precede histopathologic alterations in this disease. 相似文献
997.
6 years ago a 60-year-old man had been suffering from chronic diarrhea, weight loss and epigastric pain. Some years before he had developed joint pain, symmetric at both hands and feet. Duodenal biopsy and PCR reaction revealed Whipple's disease. Treatment with Co-trimoxazole for more than 21 months achieved remission. 6 years after diagnosis of Whipple's disease the patient presented with multilocal lymphadenopathy. Malignant Non-Hodgkin-Lymphoma (Centrocytom) stage PS IV b was diagnosed. COP-chemotherapy (Vincristine, Cyclophosphamide, Prednisone) achieved partial remission up to now. Whether the appearance of the malignant lymphoma is a consequence of Whipple's disease or a second neoplastic disease remains to be answered by further epidemiological studies. 相似文献
998.
999.
Kirchner J Schilling EM Kirchner TH Stückle C Liermann D Peters J 《R?ntgenpraxis; Zeitschrift für radiologische Technik》2001,53(6):256-259
Progressive massive fibrosis (PMF) of the lung is caused by coalescence of fibrotic nodules. The center of the PMF often displays necrotic areas. If the necrosis gets in contact to the bronchial system cavitation may occur. We report on a 68 year old patient suffering from severe silicosis of the lung and metastatic spread of a histologically proven lung cancer into the brain. The patient who was administered to the hospital under the intention of cerebral radiotherapy showed a colliquative PMF in the right upper lobe with cavitation and expectoration of large amounts of black-stained sputum (melanoptysis). 相似文献
1000.
Supplementary vitamin C (2 x 500 mg tablets daily) or a matched placebo was administered to 10 and 6 ultramarathon athletes respectively for 7 days prior to participation in a 90 kilometer running event, as well as on the day of the race and for 2 days after its completion. Circulating concentrations of vitamins A, C and E, as well as those of leukocytes and platelets, myeloperoxidase, C-reactive protein (CRP), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF), cortisol, and creatine kinase were measured 16 hours before the race and at 30 min, 24 hours, and 48 hours after completion. Pre-race vitamin C concentrations in the supplemented group were unchanged after the race (118.2 +/- 15.9 and 115.9 +/- 11.9 micromol/l) while an increase was observed in the placebo group immediately post-race (85.8 +/- 11.9 to 107.4 +/- 18.8 micromol), with a return to pre-race values after 24 hours. Immediately on completion of the race transient elevations occurred in the concentrations of circulating neutrophils, monocytes and platelets, IL-6, cortisol, CRP, and creatine kinase in both groups. In the supplemented group the concentrations of CRP were significantly higher (p < 0.01) at each of the post-race time-points while those of cortisol were 30% lower immediately post-race. These observations provide evidence that supplementation with vitamin C may blunt the adaptive mobilization of this vitamin from the adrenals during exercise-induced oxidative stress and may be associated with an enhancement of the acute phase protein response and attenuation of the exercise-induced increase in serum cortisol. 相似文献