全文获取类型
收费全文 | 1216篇 |
免费 | 72篇 |
国内免费 | 8篇 |
专业分类
耳鼻咽喉 | 3篇 |
儿科学 | 45篇 |
妇产科学 | 23篇 |
基础医学 | 166篇 |
口腔科学 | 18篇 |
临床医学 | 114篇 |
内科学 | 310篇 |
皮肤病学 | 12篇 |
神经病学 | 54篇 |
特种医学 | 28篇 |
外科学 | 177篇 |
综合类 | 27篇 |
预防医学 | 95篇 |
眼科学 | 21篇 |
药学 | 131篇 |
中国医学 | 13篇 |
肿瘤学 | 59篇 |
出版年
2023年 | 24篇 |
2022年 | 44篇 |
2021年 | 77篇 |
2020年 | 30篇 |
2019年 | 62篇 |
2018年 | 55篇 |
2017年 | 36篇 |
2016年 | 25篇 |
2015年 | 47篇 |
2014年 | 57篇 |
2013年 | 67篇 |
2012年 | 95篇 |
2011年 | 93篇 |
2010年 | 42篇 |
2009年 | 44篇 |
2008年 | 64篇 |
2007年 | 63篇 |
2006年 | 64篇 |
2005年 | 51篇 |
2004年 | 55篇 |
2003年 | 50篇 |
2002年 | 29篇 |
2001年 | 13篇 |
2000年 | 18篇 |
1999年 | 12篇 |
1998年 | 4篇 |
1997年 | 11篇 |
1996年 | 6篇 |
1995年 | 4篇 |
1994年 | 6篇 |
1993年 | 4篇 |
1992年 | 2篇 |
1991年 | 3篇 |
1990年 | 5篇 |
1989年 | 5篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1984年 | 7篇 |
1983年 | 4篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 3篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有1296条查询结果,搜索用时 15 毫秒
1.
2.
3.
M Afzal A Baez-Giangreco A N al Jaser V C Onuora 《Archives of pathology & laboratory medicine》1992,116(12):1366-1367
A 37-year-old Bangladeshi presented with large bilateral masses involving the hilus of the kidneys. No lymphadenopathy was noted. Nephrectomy was performed. Histopathologically, it revealed a lymphohistiocytic and plasma cell inflammatory tumoral proliferation with characteristic lymphophagocytosis by the S100-positive-CD1-negative histiocytes. Extranodal presentation of sinus histiocytosis with massive lymphadenopathy (Rosai-Dorfman disease) should be entertained in the differential diagnosis of bilateral masses involving the kidneys. 相似文献
4.
5.
Mohrs M Blankespoor CM Wang ZE Loots GG Afzal V Hadeiba H Shinkai K Rubin EM Locksley RM 《Nature immunology》2001,2(9):842-847
Mechanisms that underlie the patterning of cytokine expression in T helper (T(H)) cell subsets remain incompletely defined. An evolutionarily conserved approximately 400-bp noncoding sequence in the intergenic region between the genes Il4 and Il13, designated conserved noncoding sequence 1 (CNS-1), was deleted in mice. The capacity to develop T(H)2 cells was compromised in vitro and in vivo in the absence of CNS-1. Despite the profound effect in T cells, mast cells from CNS-1(-/-) mice maintained their capacity to produce interleukin 4. A T cell-specific element critical for the optimal expression of type 2 cytokines may represent the evolution of a regulatory sequence exploited by adaptive immunity. 相似文献
6.
PURPOSE: We investigated differences in the rate of homologous blood transfusion and the degree of anemia to determine whether it is rational to have patients donate autologous blood before radical prostatectomy. MATERIALS AND METHODS: We retrospectively reviewed the charts of 221 consecutive men who underwent radical retropubic prostatectomy performed by 1 surgeon in a 14-month period. About half of the patients donated autologous blood preoperatively. We evaluated perioperative hemoglobin, and the rate of autologous and homologous transfusion. RESULTS: The groups did not significantly differ in terms of demographic data, co-morbid conditions, clinical variables or hospitalization. Preoperatively mean hemoglobin plus or minus standard deviation was 13.4 +/- 1 and 14.7 +/- 1 gm./dl. in patients who did and did not donate blood, while homologous transfusion was required in 1 (1%) and 4 (3.5%), respectively (p = 0. 18). At hospital discharge anemia was more prevalent in nondonors. Of the men who did versus did not donate blood hemoglobin was less than 10 and less than 9 gm./dl. in 8.4% versus 34% (p <0.0001), and 12.5% versus 0% (p <0.0004), respectively. CONCLUSIONS: Our retrospective review of a cohort of patients who underwent radical retropubic prostatectomy showed no difference in homologous blood transfusion based on preoperative autologous donation status. Autologous donors had lower hemoglobin preoperatively, a higher rate of transfused units and higher hemoglobin at hospital discharge. Preoperative donation of autologous blood may not decrease the need for homologous transfusion in healthy patients undergoing radical retropubic prostatectomy. 相似文献
7.
Inflammatory bowel disease. 总被引:1,自引:0,他引:1
R M Beattie N M Croft J M Fell N A Afzal R B Heuschkel 《Archives of disease in childhood》2006,91(5):426-432
Twenty five per cent of inflammatory bowel disease presents in childhood. Growth and nutrition are key issues in the management with the aim of treatment being to induce and then maintain disease remission with minimal side effects. Only 25% of Crohn's disease presents with the classic triad of abdominal pain, weight loss, and diarrhoea. Most children with ulcerative colitis have blood in the stool at presentation. Inflammatory markers are usually although not invariably raised at presentation (particularly in Crohn's disease). Full investigation includes upper gastrointestinal endoscopy and ileocolonoscopy. Treatment requires multidisciplinary input as part of a clinical network led by a paediatrician with special expertise in the management of the condition. 相似文献
8.
Kristini K Miles Stephan T Stern Philip C Smith Fay K Kessler Shazia Ali Joseph K Ritter 《Drug metabolism and disposition》2005,33(10):1513-1520
Mycophenolic acid (MPA; 1,3-dihydro-4-hydroxy-6-methoxy-7-methyl-3-oxo-5-isobenzylfuranyl)-4-methyl-4-hexenoate), the active metabolite of the immunosuppressant prodrug, mycophenolate mofetil, undergoes glucuronidation to its 7-O-glucuronide as a primary route of metabolism. Because differences in glucuronidation may influence the efficacy and/or toxicity of MPA, we investigated the MPA UDP-glucuronosyltransferase (UGT) activities of human liver microsomes (HLMs) and rat liver microsomes with the goal of identifying UGTs responsible for MPA catalysis. HLMs (n = 23) exhibited higher average MPA glucuronidation rates (14.7 versus 6.0 nmol/mg/min, respectively, p < 0.001) and higher apparent affinity for MPA (K(m) = 0.082 mM versus 0.20 mM, p < 0.001) compared with rat liver microsomes. MPA UGT activities were reduced >80% in liver microsomes from Gunn rats. To identify the active enzymes, human and rat UGT1A enzymes were screened for MPA-glucuronidating activity. UGT1A9 was the only human liver-expressed UGT1A enzyme with significant activity and exhibited both high affinity (K(m) = 0.077 mM) and high activity (V(max) = 28 nmol x min(-1) x mg(-1)). Spearman correlation analyses revealed a stronger relationship between HLM MPA UGT activities and 1A9-like content (r(2) = 0.79) relative to 1A1 (r(2) = 0.20), 1A4-like (r(2) = 0.22), and 1A6 (r(2) = 0.41) protein. A different profile was observed for rat with three active liver-expressed UGT1A enzymes: 1A1 (medium affinity/capacity), 1A6 (low affinity/medium capacity), and 1A7 (high affinity/capacity). Our data suggest that UGT1A enzymes are the major contributors to hepatic MPA metabolism in both species, but 1A9 is dominant in human, whereas 1A1 and 1A7 are likely the principal mediators in control rat liver. This information should be useful for interpretation of MPA pharmacokinetic and toxicity data in clinical and animal studies. 相似文献
9.
Mohammed Najeeb Al-Hashem Muhammad Nasir Amin Ali Ajwad Muhammad Afzal Kaffayatullah Khan Muhammad Iftikhar Faraz Muhammad Ghulam Qadir Hayat Khan 《Materials》2022,15(22)
Due to the increasing prices of cement and its harmful effect on the environment, the use of cement has become highly unsustainable in concrete. There is a considerable need for promoting the use of cement replacement materials. This study investigates the effect of variable percentages of metakaolin (MK) on the mechanical and durability performance of concrete. Kaolin clay (KC) was used in the current research to prepare the MK by the calcination process; it was ground in a ball mill to its maximum achievable fineness value of 2550 m2/Kg. Four replacement levels of MK, i.e., 5%, 10%, 15%, and 20% by weight of cement, in addition to control samples, at a constant water-to-cement (w/c) ratio of 0.55 were used. For evaluating the mechanical and durability performance, 27 cubes (6 in. × 6 in. × 6 in.) and 6 cylinders (3.875 in. diameter, 2 in. height) were cast for each mix. These samples were tested for compressive strength under standard conditions and in an acidic environment, in addition to being subjected to water permeability, sorptivity, and water absorption tests. Chemical analysis revealed that MK could be used as pozzolana as per the American Society for Testing and Materials (ASTM C 618:2003). The results demonstrated an increased compressive strength of concrete owing to an increased percentage of MK in the mix with aging. In particular, the concrete having 20% MK after curing under standard conditions exhibited 33.43% higher compressive strength at 90 days as compared to similarly aged control concrete. However, with increasing MK, the workability of concrete decreased drastically. After being subjected to an acid attack (immersing concrete cubes in 2% sulfuric acid solution), the samples exhibited a significant decrease in compressive strength at 90 days in comparison to those without acid attack at the same age. The density of acid attack increased with increasing MK with a maximum corresponding to 5% MK concrete. The current findings suggest that the local MK has the potential to produce good-quality concrete in a normal environment. 相似文献
10.
Attia Hamid Asma Zafar Sabahat Latif Liangcai Peng Yanting Wang Iram Liaqat Muhammad Sohail Afzal Ikram ul-Haq Muhammad Nauman Aftab 《RSC advances》2023,13(2):1434
A low temperature alkali (LTA) pretreatment method was used to treat wheat straw. In order to obtain good results, different factors like temperature, incubation time, NaOH concentration and solid to liquid ratio for the pretreatment process were optimized. Wheat straw is a potential biomass for the production of monomeric sugars. The objective of the current study was to observe the saccharification (%) of wheat straw with immobilized magnetic nanoparticles (MNPs). For this purpose, immobilized MNPs of purified β-xylanase enzyme was used for hydrolysis of pretreated wheat straw. Wheat straw was pretreated using the LTA method and analyzed by SEM analysis. After completion of the saccharification process, saccharification% was calculated by using a DNS method. Scanning electron micrographs revealed that the hemicellulose, cellulose and lignin were partially removed and changes in the cell wall structure of the wheat straw had caused it to become deformed, increasing the specific surface area, so more fibers of the wheat straw were exposed to the immobilized β-xylanase enzyme after alkali pretreatment. The maximum saccharification potential of wheat straw was about 20.61% obtained after pretreatment with optimized conditions of 6% NaOH, 1/10 S/L, 30 °C and 72 hours. Our results indicate the reusability of the β-xylanase enzyme immobilized magnetic nanoparticles and showed a 15% residual activity after the 11th cycle. HPLC analysis of the enzyme-hydrolyzed filtrate also revealed the presence of sugars like xylose, arabinose, xylobiose, xylotriose and xylotetrose. The time duration of the pretreatment has an important effect on thermal energy consumption for the low-temperature alkali method.A low temperature alkali (LTA) pretreatment method was used to treat wheat straw. 相似文献