全文获取类型
收费全文 | 94706篇 |
免费 | 5889篇 |
国内免费 | 728篇 |
专业分类
耳鼻咽喉 | 1092篇 |
儿科学 | 2870篇 |
妇产科学 | 2403篇 |
基础医学 | 12796篇 |
口腔科学 | 2127篇 |
临床医学 | 7633篇 |
内科学 | 20622篇 |
皮肤病学 | 1952篇 |
神经病学 | 8945篇 |
特种医学 | 3710篇 |
外国民族医学 | 23篇 |
外科学 | 13290篇 |
综合类 | 1651篇 |
一般理论 | 47篇 |
预防医学 | 5493篇 |
眼科学 | 1492篇 |
药学 | 7730篇 |
3篇 | |
中国医学 | 508篇 |
肿瘤学 | 6936篇 |
出版年
2023年 | 397篇 |
2022年 | 955篇 |
2021年 | 1743篇 |
2020年 | 1124篇 |
2019年 | 1585篇 |
2018年 | 1992篇 |
2017年 | 1539篇 |
2016年 | 1588篇 |
2015年 | 1852篇 |
2014年 | 2427篇 |
2013年 | 3608篇 |
2012年 | 4797篇 |
2011年 | 4996篇 |
2010年 | 3272篇 |
2009年 | 2845篇 |
2008年 | 4395篇 |
2007年 | 4616篇 |
2006年 | 4386篇 |
2005年 | 4190篇 |
2004年 | 4545篇 |
2003年 | 4370篇 |
2002年 | 4443篇 |
2001年 | 3719篇 |
2000年 | 3666篇 |
1999年 | 2972篇 |
1998年 | 1121篇 |
1997年 | 883篇 |
1996年 | 810篇 |
1995年 | 780篇 |
1994年 | 687篇 |
1993年 | 666篇 |
1992年 | 1783篇 |
1991年 | 1772篇 |
1990年 | 1502篇 |
1989年 | 1453篇 |
1988年 | 1329篇 |
1987年 | 1193篇 |
1986年 | 1186篇 |
1985年 | 1059篇 |
1984年 | 779篇 |
1983年 | 703篇 |
1982年 | 450篇 |
1981年 | 390篇 |
1979年 | 582篇 |
1978年 | 427篇 |
1975年 | 435篇 |
1974年 | 492篇 |
1973年 | 469篇 |
1972年 | 429篇 |
1971年 | 397篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
871.
P Rebuffat L Cavallini A S Belloni G Mazzocchi A Coi G P De Tos G G Nussdorfer 《Journal of submicroscopic cytology and pathology》1989,21(1):73-81
The effect of a prolonged (7-day) ACTH administration on rat zona fasciculata cells and its reversal after cessation of treatment was investigated by morphometry. ACTH treatment caused a notable cell hypertrophy, which was mainly due to the increase in the volume of the mitochondrial compartment and to smooth endoplasmic reticulum (SER) proliferation, and a conspicuous rise in the basal level of corticosterone. After cessation of ACTH administration, rat zona fasciculata cells underwent a time-dependent atrophy, so that after 5 days they resembled those of control animals, and the blood concentration of corticosterone reverted to the base-line value. The cell atrophy was provoked by the decrease in the volumes of the mitochondrial compartment and SER, and was associated with a striking time-dependent accumulation of dense bodies. Stereology demonstrated that during the first two days after ACTH withdrawal the decrease of SER prevailed over that of the mitochondrial compartment, while the reverse occurred during the remaining three days. The increase in the volume of dense-body compartment, though largely due to the accumulation of residual bodies, was mainly coupled with a rise in the volume of the microautophagic-vacuole compartment during the first two days after ACTH cessation and with an increase in that of the macroautophagic-vacuole compartment during the following three days. The hypothesis is advanced that both micro- and macroautophagy play a role in the reversal of ACTH-induced hypertrophy of rat zona fasciculata cells after cessation of treatment, the first process being mainly involved in the elimination of SER, and the second one in the degradation of mitochondria. 相似文献
872.
Since the identification of the BRCA1 and BRCA2 genes (MIM#s 113705 and 600185), more than hundred different mutations throughout both genes have been reported. Recurrent mutations are rare and mainly due to founder effects. We analyzed 12 sporadic female patients with breast cancer before age 35, as well as 16 unrelated families, presenting with either (i) at least 3 first degree relatives with breast and/or ovarian cancer diagnosed at any age, or (ii) at least 2 first and/or second degree relatives with breast and/or ovarian cancer before age 45 years. We performed a protein truncation test for BRCA1 exon 11 and BRCA2 exons 10 and 11 and heteroduplex analysis for all the remaining exons of BRCA1 and 2. Presence of genomic deletions encompassing exons 13 or 22 of BRCA1, known to be Dutch founder mutations, was investigated by PCR. In 6/16 (37.5%) unrelated families the causal mutation in either the BRCA1 or BRCA2 gene was identified. Four different mutations were found in the BRCA1 gene: IVS5+3A>G (intron 5), 1191delC (exon 11), R1443X (exon 13), IVS22+5G>A (intron 22) and two in the BRCA2 gene: 6503delTT (exon 11), 6831delTG (exon 11). 1191delC (BRCA1) and 6831delTG (BRCA2) are novel mutations. IVS5+3A>G in exon 5 of BRCA1 published by Peelen et al. (1997) as a novel Belgian mutation, was identified in one additional family, not fulfilling our inclusion criteria. In the group of 12 sporadic female patients no mutations were found. 相似文献
873.
874.
A Cavazza E Nigrisoli L De Marco M Paci V Annessi L Agostini G Gardini 《Pathologica》2001,93(6):681-684
We describe a case of bronchiolitis obliterans-organizing pneumonia (BOOP) with asbestos bodies. A 65-year-old man, treated in the past for gastric lymphoma and with an history of asbestos exposure, presented with fever and two nodular opacities in the lower lobe of the left lung. Histologic examination revealed a BOOP pattern; in the inflammatory tissue some asbestos bodies were present. Patients exposed to asbestos may rarely present with localized inflammatory pulmonary lesions. In these cases, the possible etiopathogenetic role of asbestos needs further studies. 相似文献
875.
De Boeck M Lardau S Buchet JP Kirsch-Volders M Lison D 《Environmental and molecular mutagenesis》2000,36(2):151-160
Mortality studies have shown that, in the past, lung cancer occurred after exposure to mixtures of cobalt metal and metallic carbide particles, the main constituents of hard metals, but apparently not when exposure was to cobalt alone. The major objective of this biomonitoring study was to assess genotoxic effects as a measure for carcinogenic risk in workers from cobalt refineries and hard metal plants currently exposed to the threshold limit value/time-weighted average (TLV-TWA) for cobalt-containing dust. The study comprised three groups of workers: 35 workers exposed to cobalt dust from three refineries, 29 workers exposed to hard metal dust from two producing plants, and 35 matched control subjects recruited from the respective plants. The study design integrated complementary methodologies to assess biomarkers of effects that represent both initial DNA damage (8-hydroxydeoxyguanosine [8-OHdG] in urine and comet assay on lymphocytes) and definitive chromosome breakage/loss (micronuclei in lymphocytes). Cobalt and cotinine were determined in urine as a measure for cobalt exposure and recent smoking, respectively. No significant increase of genotoxic effects was detected in workers exposed to cobalt-containing dust as compared to controls. No difference in any genotoxicity biomarker was found between workers exposed to cobalt and hard metal dusts. Multiple regression analysis indicated that workers who smoked and were exposed to hard metal dusts had elevated 8-OHdG and micronuclei values. Because this observation is in line with a previous epidemiological study of an increased risk of dying from lung cancer in workers from the hard metal industry who smoked, it is concluded that this specific occupational group needs closer medical surveillance. 相似文献
876.
活体亲属供肾肾移植的临床分析 总被引:7,自引:0,他引:7
目的 总结分析活体亲属供肾肾移植的手术和治疗经验 ,探讨其临床效果 .方法 回顾性分析 33例活体亲属供肾肾移植的临床资料 ,包括手术方法和创新、免疫抑制药物的用药方案及临床效果 .结果 本组全部切取左肾 ,经腹手术 ,手术顺利 ,移植肾在开放血液循环后 1~ 10分钟内分泌尿液 .供体肾功能在 1周内恢复正常 ,未出现严重并发症 .受者仅 2例出现急性排斥反应 .全部受者至今存活 ,肾功能良好 .结论 活体亲属供肾 ,移植效果明显优于尸体供肾肾移植 .排斥反应发生率低 ,恢复顺利 相似文献
877.
Leroy X Wacrenier A De la Taille A Gosset P Saint F Biserte J Gosselin B 《APMIS : acta pathologica, microbiologica, et immunologica Scandinavica》2001,109(6):469-473
Sarcomatoid renal cell carcinomas (SRC) are rare neoplasms associated with a very poor prognosis. The aim of this study was to evaluate biomarker expression and clinical significance in this uncommon renal cancer. Cytokeratin, epithelial membrane antigen, vimentin, desmin, smooth muscle actin, CD34, S-100 protein, MIB 1, p53, Fas and Fas ligand immunohistochemical expression was investigated in seven renal cell carcinomas with sarcomatoid changes. No significant difference between sarcomatoid and nonsarcomatoid areas was observed with the different biomarkers, excepted for Fas ligand. Fas expression was diffuse in sarcomatoid and nonsarcomatoid areas. However, Fas ligand had a higher expression in sarcomatoid in comparison to nonsarcomatoid areas. Our results showed that Fas and Fas ligand are both expressed in renal cancer. We suggest that the aggressive behavior of sarcomatoid carcinoma may be related to a higher expression of Fas ligand by tumor sarcomatoid cells. These findings may indicate that Fas ligand is a possible therapeutic molecular target for treatment of SRC. 相似文献
878.
Vergote K De Deene Y Duthoy W De Gersem W De Neve W Achten E De Wagter C 《Physics in medicine and biology》2004,49(2):287-305
Polymer gel dosimetry was used to assess an intensity-modulated arc therapy (IMAT) treatment for whole abdominopelvic radiotherapy. Prior to the actual dosimetry experiment, a uniformity study on an unirradiated anthropomorphic phantom was carried out. A correction was performed to minimize deviations in the R2 maps due to radiofrequency non-uniformities. In addition, compensation strategies were implemented to limit R2 deviations caused by temperature drift during scanning. Inter- and intra-slice R2 deviations in the phantom were thereby significantly reduced. This was verified in an investigative study where the same phantom was irradiated with two rectangular superimposed beams: structural deviations between gel measurements and computational results remained below 3% outside high dose gradient regions; the spatial shift in those regions was within 2.5 mm. When comparing gel measurements with computational results for the IMAT treatment, dose deviations were noted in the liver and right kidney, but the dose-volume constraints were met. Root-mean-square differences between both dose distributions were within 5% with spatial deviations not more than 2.5 mm. Dose fluctuations due to gantry angle discretization in the dose computation algorithm were particularly noticeable in the low-dose region. 相似文献
879.
Helicobacter pylori infection affects eosinophilic cationic protein in the gastric juice of patients with idiopathic chronic urticaria 总被引:6,自引:0,他引:6
Ojetti V Armuzzi A De Luca A Nucera E Franceschi F Candelli M Zannoni GF Danese S Di Caro S Vastola M Schiavino D Gasbarrini G Patriarca G Pola P Gasbarrini A 《International archives of allergy and immunology》2001,125(1):66-72
BACKGROUND: Helicobacter pylori, the main cause of gastritis and peptic ulcer, has been associated with idiopathic chronic urticaria (ICU), an immunological skin disorder of unknown origin. Eosinophilic cationic protein (ECP) is a cytotoxic molecule secreted by the activated eosinophils involved in the pathogenesis of ICU. We assessed serum/gastric juice ECP levels and gastric mucosal eosinophil infiltration in ICU patients infected or not with H. pylori and evaluated the modification after bacterium eradication. METHODS: 33 patients with ICU and 25 dyspeptic controls underwent upper gastrointestinal endoscopy for histological evaluation and assessment of H. pylori infection. One-week triple therapy was given to H. pylori-positive patients. Serum and gastric juice ECP levels, eosinophil infiltration from gastric mucosal sections and urticaria symptoms were evaluated in all patients at enrollment and 8 weeks after eradication. RESULTS: 19 of 33 (57%) ICU patients and 16 of 25 (64%) controls were found to be infected with H. pylori. Serum ECP was significantly higher in ICU patients compared to controls, regardless of infectious status. Gastric juice ECP and gastric eosinophil infiltration were significantly higher in infected ICU patients when compared both to uninfected ICU patients and controls. H. pylori eradication determined a significant decrease in gastric juice ECP and gastric eosinophil infiltration only in ICU patients. Moreover, a total or partial remission of urticaria symptoms was observed only in ICU patients in whom the bacterium was eradicated. CONCLUSIONS: Although H. pylori infection affects gastric juice ECP and eosinophil infiltration of ICU patients, the role of the bacterium in the pathogenesis of this skin disorder still remains uncertain. 相似文献
880.
Murri R Ammassari A Pezzotti P Cingolani A De Luca A Pallavicini F Grillo R Antinori A 《Journal of acquired immune deficiency syndromes (1999)》2001,27(1):49-55
We assessed the incidence and determinants of bacteremia, pneumonia, and sinusitis/otitis in HIV-positive people receiving cotrimoxazole (CTX) or dapsone-pyrimethamine (DP) for primary prophylaxis of Pneumocystis carinii pneumonia (PCP) and toxoplasmic encephalitis (TE) within a randomized clinical trial. In total, 244 patients were randomized: 122 were assigned to CTX and 122 to DP. In the cohort, 22 bacteremia, 63 pneumonia, and 39 sinusitis/otitis cases were observed. Incidence rates of bacteremia, pneumonia, and sinusitis/otitis as well as the 2-year probability of remaining free from any bacterial infection were not significantly different between the two groups. At multivariate analysis, the risks of developing bacteremia and pneumonia were found to be independently increased by the use of a central venous catheter (hazard ratio [HR], 4.48; p <.05 and HR, 4.13; p <.01, respectively) and by hospitalization (HR, 28.82; p <.05 and HR, 10.15; p <.05, respectively). In conclusion, CTX at the dosage employed for primary PCP/TE prophylaxis does not seem to protect against bacterial infections more than second-line DP. 相似文献