全文获取类型
收费全文 | 39548篇 |
免费 | 14892篇 |
国内免费 | 396篇 |
专业分类
耳鼻咽喉 | 180篇 |
儿科学 | 359篇 |
妇产科学 | 281篇 |
基础医学 | 10661篇 |
口腔科学 | 745篇 |
临床医学 | 8489篇 |
内科学 | 13000篇 |
皮肤病学 | 515篇 |
神经病学 | 1953篇 |
特种医学 | 972篇 |
外国民族医学 | 1篇 |
外科学 | 5056篇 |
综合类 | 916篇 |
一般理论 | 1篇 |
预防医学 | 4777篇 |
眼科学 | 495篇 |
药学 | 4000篇 |
1篇 | |
中国医学 | 157篇 |
肿瘤学 | 2277篇 |
出版年
2022年 | 311篇 |
2021年 | 5095篇 |
2020年 | 1262篇 |
2019年 | 587篇 |
2018年 | 500篇 |
2017年 | 303篇 |
2016年 | 1105篇 |
2015年 | 4185篇 |
2014年 | 4434篇 |
2013年 | 3630篇 |
2012年 | 2461篇 |
2011年 | 2409篇 |
2010年 | 3023篇 |
2009年 | 3276篇 |
2008年 | 2463篇 |
2007年 | 1131篇 |
2006年 | 871篇 |
2005年 | 685篇 |
2004年 | 751篇 |
2003年 | 566篇 |
2002年 | 505篇 |
2001年 | 490篇 |
2000年 | 374篇 |
1999年 | 482篇 |
1998年 | 1842篇 |
1997年 | 1450篇 |
1996年 | 1447篇 |
1995年 | 1206篇 |
1994年 | 1161篇 |
1993年 | 960篇 |
1992年 | 332篇 |
1991年 | 280篇 |
1990年 | 235篇 |
1989年 | 182篇 |
1988年 | 169篇 |
1987年 | 254篇 |
1986年 | 286篇 |
1985年 | 218篇 |
1983年 | 204篇 |
1982年 | 203篇 |
1981年 | 204篇 |
1980年 | 205篇 |
1979年 | 193篇 |
1978年 | 184篇 |
1977年 | 203篇 |
1976年 | 174篇 |
1975年 | 183篇 |
1974年 | 240篇 |
1973年 | 183篇 |
1972年 | 173篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
51.
Ludwig Labler Marius Keel Otmar Trentz Michael Heinzelmann 《European spine journal》2006,15(9):1388-1396
The use of vacuum assisted closure (V.A.C.) therapy in postoperative infections after dorsal spinal surgery was studied retrospectively. Successful treatment was defined as a stable healed wound that showed no signs of acute or chronic infection. The treatment of the infected back wounds consisted of repeated debridement, irrigation and open wound treatment with temporary closure by V.A.C. The instrumentation was exchanged or removed if necessary. Fifteen patients with deep subfascial infections after posterior spinal surgery were treated. The implants were exchanged in seven cases, removed completely in five cases and left without changing in one case. In two cases spinal surgery consisted of laminectomy without instrumentation. In two cases only the wound defects were closed by muscle flap, the remaining ones were closed by delayed suturing. Antibiotic treatment was necessary in all cases. Follow up was possible in 14 patients. One patient showed a new infection after treatment. The study illustrates the usefulness of V.A.C. therapy as a new alternative management for wound conditioning of complex back wounds after deep subfascial infection. 相似文献
53.
Predictors of clustering of tuberculosis in Greater Vancouver: a molecular epidemiologic study 总被引:3,自引:0,他引:3 下载免费PDF全文
54.
Cloning of a cDNA for the FAD-linked glycerol-3-phosphate dehydrogenase from rat liver and its regulation by thyroid hormones. 总被引:2,自引:0,他引:2 下载免费PDF全文
S Müller H J Seitz 《Proceedings of the National Academy of Sciences of the United States of America》1994,91(22):10581-10585
A full-length 2.4-kb cDNA for the FAD-linked glycerol-3-phosphate dehydrogenase (EC 1.1.99.5) was cloned from rat liver using PCR techniques. The cloned gene encodes a protein of 727 amino acids. The calculated molecular mass of 80,898 Da is higher than the apparent molecular mass observed by SDS/PAGE (74,000 Da) of the purified enzyme. This result indicates that the enzyme is synthesized as a precursor with a putative mitochondrial signal sequence. mRNA for this gene was detected in liver, heart, muscle, brain, testes, and pancreas. With the exception of testes, basal expression levels were very low in all tissues examined. However, application of thyroid hormones led to a 10- to 15-fold increase in liver glycerol-3-phosphate dehydrogenase mRNA, whereas hypothyroidism further decreased the mRNA level. 相似文献
55.
Six cases of mycobacteriosis due to Mycobacterium genavense in three budgerigars (Melopsittacus undulatus), one orange-winged amazon (Amazona amazonica), one flycatcher (Cyanoptila cyanomelana), and one zebra finch (Taeniopygia guttata) are discussed. Gross lesions associated with the infection included a high degree of muscular wasting (five cases), hepatomegaly (four cases), and thickening of the wall of the small intestine (four cases). Granulomas were found in the lung (one case) and the subcutis (one case). Acid-fast bacilli were detected in the liver of all six birds. Only the use of acidic BACTEC mediums consistently led to growth, whereas the egg-based medium failed. These findings point to a possible role of the environment as a reservoir for M. genavense. 相似文献
56.
A species-specific nucleotide sequence of Mycobacterium tuberculosis encodes a protein that exhibits hemolytic activity when expressed in Escherichia coli. 总被引:3,自引:2,他引:1 下载免费PDF全文
Species-specific proteins may be implicated in the unique pathogenic mechanisms characteristic of Mycobacterium tuberculosis. In previous studies, a 3.0-kb species-specific DNA fragment of M. tuberculosis was identified (C. A. Parra, L. P. Londo000f1;o, P. del Portillo, and M. E. Patarroyo, Immun. 59:3411-3417, 1991). The nucleotide sequence of this 3.0-kb fragment has been obtained. This sequence was shown to contain two open reading frames (ORFs) whose putative gene products share 68.9% identity between each other. The major ORF shows 57.8% similarity with PLC-N and 53.2% similarity with PLC-H, two phospholipase C enzymes from Pseudomonas aeruginosa. The major ORF was amplified by PCR and cloned into the pGEX-5T expression vector. Cell extracts of Escherichia coli overexpressing this glutathione S-transferase fusion protein were shown to produce beta-hemolysis suggestive of phospholipase activity. Since phospholipase C enzymes have been reported as virulence factors of P. aeruginosa and also of the intracellular pathogen Listeria monocytogenes, it is possible that the proteins identified in this study could also play a role in sustaining tuberculosis infection in humans. 相似文献
57.
Conditionally replicating luciferase reporter phages: improved sensitivity for rapid detection and assessment of drug susceptibility of Mycobacterium tuberculosis. 总被引:7,自引:1,他引:6 下载免费PDF全文
C Carrire P F Riska O Zimhony J Kriakov S Bardarov J Burns J Chan W R Jacobs Jr 《Journal of clinical microbiology》1997,35(12):3232-3239
TM4 is a lytic mycobacteriophage which infects mycobacteria of clinical importance. A luciferase reporter phage, phAE40, has been constructed from TM4 and was previously shown to be useful for the rapid detection and drug susceptibility testing of Mycobacterium tuberculosis. However, the lytic nature of the phage results in a loss of detectable light output and limits the sensitivity of detection. We describe several strategies aimed at improving the luciferase activity generated by TM4 luciferase phages, including (i) varying the position of the luciferase gene in the phage genome, (ii) isolating host-range mutants of the phage, and (iii) introducing temperature-sensitive mutations in the phage such that it will not replicate at the infecting temperature. Several new phages generated by these methods show increased intensity of luciferase production compared to the first-generation reporter phage phAE40, and one phage, phAE88, also demonstrates an enhanced duration of luciferase activity. This has allowed the detection of as few as 120 BCG cells and the determination of drug susceptibilities of M. tuberculosis in as little as 1 day. 相似文献
58.
Formoterol, a new long acting beta 2 agonist for inhalation twice daily, compared with salbutamol in the treatment of asthma. 总被引:5,自引:2,他引:3 下载免费PDF全文
Sixteen patients with stable chronic asthma participated in a double blind crossover study comparing the new inhaled long acting beta 2 agonist formoterol with salbutamol. Inhaled (n = 15) and oral steroid (n = 1) treatment were maintained at the same daily dose throughout the study. For four weeks the patients received either formoterol 24 micrograms twice daily or salbutamol 400 micrograms twice daily, plus additional puffs (with the same drug) when needed. Asthma symptoms, additional puffs of beta 2 agonist, peak expiratory flow (PEF), and side effects were recorded daily. During treatment with formoterol the patients used fewer additional puffs of beta 2 agonist, had better symptom scores, less disturbed sleep, more days without additional aerosol, and higher PEF both morning and evening than during salbutamol treatment. Thus formoterol 24 micrograms twice daily gave long lasting bronchodilatation and asthma symptoms were well controlled with regular twice daily administration. 相似文献
59.
60.