全文获取类型
收费全文 | 10440篇 |
免费 | 502篇 |
国内免费 | 35篇 |
专业分类
耳鼻咽喉 | 176篇 |
儿科学 | 210篇 |
妇产科学 | 185篇 |
基础医学 | 1756篇 |
口腔科学 | 236篇 |
临床医学 | 841篇 |
内科学 | 2063篇 |
皮肤病学 | 184篇 |
神经病学 | 1054篇 |
特种医学 | 644篇 |
外国民族医学 | 1篇 |
外科学 | 1261篇 |
综合类 | 73篇 |
预防医学 | 437篇 |
眼科学 | 253篇 |
药学 | 1000篇 |
中国医学 | 64篇 |
肿瘤学 | 539篇 |
出版年
2022年 | 57篇 |
2021年 | 136篇 |
2020年 | 90篇 |
2019年 | 113篇 |
2018年 | 146篇 |
2017年 | 126篇 |
2016年 | 170篇 |
2015年 | 227篇 |
2014年 | 292篇 |
2013年 | 397篇 |
2012年 | 545篇 |
2011年 | 596篇 |
2010年 | 349篇 |
2009年 | 359篇 |
2008年 | 610篇 |
2007年 | 665篇 |
2006年 | 617篇 |
2005年 | 643篇 |
2004年 | 633篇 |
2003年 | 613篇 |
2002年 | 595篇 |
2001年 | 133篇 |
2000年 | 113篇 |
1999年 | 141篇 |
1998年 | 138篇 |
1997年 | 129篇 |
1996年 | 102篇 |
1995年 | 85篇 |
1994年 | 89篇 |
1993年 | 99篇 |
1992年 | 82篇 |
1991年 | 64篇 |
1990年 | 61篇 |
1989年 | 80篇 |
1988年 | 61篇 |
1987年 | 62篇 |
1986年 | 50篇 |
1985年 | 69篇 |
1984年 | 59篇 |
1983年 | 57篇 |
1982年 | 59篇 |
1981年 | 68篇 |
1980年 | 47篇 |
1979年 | 52篇 |
1978年 | 45篇 |
1977年 | 62篇 |
1976年 | 44篇 |
1975年 | 44篇 |
1973年 | 35篇 |
1963年 | 34篇 |
排序方式: 共有10000条查询结果,搜索用时 8 毫秒
41.
Sergey M. Kipriyanov Gerhard Moldenhauer Melvyn Little 《Journal of immunological methods》1997,200(1-2):69-77
We have investigated the effect of growth and induction conditions on the production of soluble single-chain Fv antibody fragments in Escherichia coli under the control of wt lac promoter. The scFv was directed into the periplasmic space by a pelB leader sequence. Addition of sucrose to the medium gave a 15–25-fold increase in the yield of soluble scFv-phOx (3.0 mg/l) for bacterial shake-tube cultures and an increase of 80–150-fold (16.5 mg/l) for shake-flask cultures. Using flask culture in the presence of 0.4 M sucrose, a significant amount of scFv was released into the medium. We found that the scFv could be made to accumulate in the periplasm or be secreted into the medium by simply changing the incubation conditions and the concentration of the inducer. The ratio between soluble antibody fragments and insoluble scFv aggregates proved to be dependent on the strength of the promoter. Lowering the incubation temperature below 20°C had no effect on the yield of soluble antibody fragments in the periplasm, but they were no longer secreted into the medium. An example of high level production in shake-flask cultures and one-step purification by immobilized metal affinity chromatography (IMAC) is described for a soluble scFv specific for the T cell surface antigen CD3. The biological activity of the purified anti-CD3 scFv was demonstrated by flow cytometry. This method should be especially useful for the functional screening of a large number of clones in small-scale cultures. 相似文献
42.
St?le Nordg?rd Gerhard Hein Brit Kari Stene Ketil Wichman Skj?stad Joachim T Maurer 《Otolaryngology--head and neck surgery》2007,136(5):818-822
OBJECTIVE: To evaluate long-term effectiveness of palatal implants for treatment of mild to moderate obstructive sleep apnea (OSA). STUDY DESIGN: A prospective study of 26 referred patients with a pretreatment apnea-hypopnea index (AHI) of 10 to 30 and a body mass index of < or =30, representing an extended follow-up of a subset of 41 patients enrolled in previous short-term trials. RESULTS: Twenty-one of 26 patients (80.8%) experienced a decrease in AHI. Fifteen of 26 patients (57.7%) had a follow-up AHI <10 at 1 year, whereas 13 patients (50%) had a 50% or greater reduction to an AHI <10 at 1 year. Mean AHI was reduced from 16.5 +/- 4.5 at baseline to 12.5 +/- 10.5 at 3 months (P < 0.014) and to 12.3 +/- 12.7 at 1 year (P < 0.019). CONCLUSIONS: Patients initially responding to palatal implants with improved AHI maintained improvement through long-term follow-up at 1 year. 相似文献
43.
Phenytoin–lipid conjugates obtained by covalent binding of hydroxymethylphenytoin to diacylglycerides and to 3-acyloxy-2-acyl-oxymethylpropionic acids formed dispersions with a particle size of 10–200 µm when briefly sonicated in a sodium taurodeoxycholate-containing ethanol–water mixture. In contrast to the corresponding bis-deacyl derivatives, the lipids were not significantly hydrolyzed in aqueous buffers and in plasma. Incubation with pancreatic lipase yielded primarily the bis-deacyl compounds, which are comparable to monoglycerides, and subsequently liberated phenytoin. The glyceride-derived prodrugs were better substrates for the enzyme than the 3-acyloxy-2-acyloxymethyl-propionic acid derivatives. It is concluded that the phenytoin lipid conjugates are hydrolyzed by pancreatic lipase in a similar manner as natural triglycerides. 相似文献
44.
45.
46.
Claudia Ladner Gerhard Ehninger K. Fred Gey Michael R. Clemens 《Cancer chemotherapy and pharmacology》1989,25(3):210-212
Summary A total of 13 patients receiving bone marrow transplants (BMT) for treatment of different haematological diseases were investigated. Conditioning therapy preceding BMT consisted of fractionated total-body irradiation (12 Gy) and high-dose chemotherapy with cyclophosphamide (2±60 mg/kg). Patients stratified to be at high risk for relapse (6/13) were additionally treated with etoposide (30 mg/kg). Plasma concentrations of absolute and lipid-standardized antioxidants (-tocopherol and -carotene) decreased following conditioning therapy, presumably as the result of an enhanced breakdown of these antioxidants. Etoposide treatment did not amplify the loss of essential anti-oxidants but significantly increased lipid hydroperoxide concentrations in serum. We suggest that the abnormal generation of lipid hydroperoxides is the result of free radical formation. 相似文献
47.
Functional analysis of the cag pathogenicity island in Helicobacter pylori isolates from patients with gastritis, peptic ulcer, and gastric cancer 总被引:9,自引:0,他引:9 下载免费PDF全文
Backert S Schwarz T Miehlke S Kirsch C Sommer C Kwok T Gerhard M Goebel UB Lehn N Koenig W Meyer TF 《Infection and immunity》2004,72(2):1043-1056
Helicobacter pylori is the causative agent of a variety of gastric diseases, but the clinical relevance of bacterial virulence factors is still controversial. Virulent strains carrying the cag pathogenicity island (cagPAI) are thought to be key players in disease development. Here, we have compared cagPAI-dependent in vitro responses in H. pylori isolates obtained from 75 patients with gastritis, peptic ulcer, and gastric cancer (n = 25 in each group). AGS gastric epithelial cells were infected with each strain and assayed for (i) CagA expression, (ii) translocation and tyrosine phosphorylation of CagA, (iii) c-Src inactivation, (iv) cortactin dephosphorylation, (v) induction of actin cytoskeletal rearrangements associated with cell elongation, (vi) induction of cellular motility, and (vii) secretion of interleukin-8. Interestingly, we found high but similar prevalences of all of these cagPAI-dependent host cell responses (ranging from 56 to 80%) among the various groups of patients. This study revealed CagA proteins with unique features, CagA subspecies of various sizes, and new functional properties for the phenotypic outcomes. We further showed that induction of AGS cell motility and elongation are two independent processes. Our data corroborate epidemiological studies, which indicate a significant association of cagPAI presence and functionality with histopathological findings in gastritis, peptic ulcer, and gastric cancer patients, thus emphasizing the importance of the cagPAI for the pathogenicity of H. pylori. Nevertheless, we found no significant association of the specific H. pylori-induced responses with any particular patient group. This may indicate that the determination of disease development is highly complex and involves multiple bacterial and/or host factors. 相似文献
48.
49.
50.
Although medical connectors compose very small parts of the extracorporeal circulation (ECC) system they represent a critical localization where early thromboembolic processes can manifest. In the present study we modified an in vitro closed-loop model with fresh human whole blood for the preclinical evaluation of the hemocompatibility of three types of medical connectors: non-coated (control); with silicone-, and heparin-coating. Each single loop consists of five polycarbonate connectors joined together by five pieces of silicone tubes. Thrombin-antithrombin-III, beta-thromboglobulin (beta-TG), PMN-Elastase, terminal complement complex, CD 11b expression, and surface-absorbed fibrinogen were measured. After 1 and 2 h recirculation, platelet loss, release of beta-TG, and adsorption of fibrinogen were significantly higher (p<0.05) within the non-coated connectors compared to the silicone- and heparin-coated groups. Following this experiment, the connectors were filled again with fresh heparinized whole blood from the same donor to evaluate the influence of prior blood contact. Here, the activation of platelets and coagulation was dependent on the duration of the blood preincubation period. Probably, the coated surfaces possess a reduced, or selective adsorption of plasma proteins, which in turn leads to a faster creation of a blood-friendly secondary superficial membrane, and prevents a further denaturation and hence activation of the adsorbed proteins. 相似文献