全文获取类型
收费全文 | 6111篇 |
免费 | 346篇 |
国内免费 | 33篇 |
专业分类
耳鼻咽喉 | 136篇 |
儿科学 | 203篇 |
妇产科学 | 183篇 |
基础医学 | 1025篇 |
口腔科学 | 69篇 |
临床医学 | 472篇 |
内科学 | 1391篇 |
皮肤病学 | 164篇 |
神经病学 | 596篇 |
特种医学 | 78篇 |
外科学 | 504篇 |
综合类 | 32篇 |
一般理论 | 1篇 |
预防医学 | 518篇 |
眼科学 | 115篇 |
药学 | 620篇 |
中国医学 | 13篇 |
肿瘤学 | 370篇 |
出版年
2023年 | 59篇 |
2022年 | 272篇 |
2021年 | 389篇 |
2020年 | 150篇 |
2019年 | 209篇 |
2018年 | 203篇 |
2017年 | 191篇 |
2016年 | 206篇 |
2015年 | 223篇 |
2014年 | 259篇 |
2013年 | 362篇 |
2012年 | 533篇 |
2011年 | 557篇 |
2010年 | 278篇 |
2009年 | 220篇 |
2008年 | 334篇 |
2007年 | 353篇 |
2006年 | 361篇 |
2005年 | 299篇 |
2004年 | 256篇 |
2003年 | 238篇 |
2002年 | 219篇 |
2001年 | 37篇 |
2000年 | 19篇 |
1999年 | 25篇 |
1998年 | 23篇 |
1997年 | 19篇 |
1996年 | 25篇 |
1995年 | 13篇 |
1994年 | 21篇 |
1993年 | 4篇 |
1992年 | 16篇 |
1991年 | 6篇 |
1990年 | 5篇 |
1989年 | 7篇 |
1988年 | 6篇 |
1987年 | 7篇 |
1985年 | 7篇 |
1983年 | 6篇 |
1982年 | 5篇 |
1981年 | 8篇 |
1980年 | 4篇 |
1974年 | 5篇 |
1973年 | 3篇 |
1972年 | 3篇 |
1971年 | 3篇 |
1969年 | 4篇 |
1968年 | 5篇 |
1967年 | 3篇 |
1965年 | 3篇 |
排序方式: 共有6490条查询结果,搜索用时 15 毫秒
51.
52.
53.
54.
Samples of mesoporous base-catalysed silica xerogel materials made by the sol-gel process were impregnated with an anticancer drug—doxorubicin, followed by different times of ageing at room temperature. The effect of ageing time on the physical and structural properties as well as sorption–desorption of the drug was investigated. The obtained results suggest an inverse relationship with a solid density and surface area increasing as the pore size and volume decrease during ageing time. These results also revealed the effect of ageing time on the efficiency of sorption–desorption of the drug. An increase in ageing time results in an increase of the efficiency of drug sorption and a decrease in the rate of drug release. 相似文献
55.
Anna Brillowska‐Dąbrowska Magdalena Wianecka Sławomir Dąbrowski Zuzana Mladenovska Józef Kur Birgitte K. Ahring 《Scandinavian journal of clinical and laboratory investigation》2013,73(8):720-730
A DNA fingerprinting method known as ALIS‐FLP (amplified ligation selected fragment‐length polymorphism) has been developed for selective and specific amplification of restriction fragments from TspRI restriction endonuclease digested genomic DNA. The method is similar to AFLP, but differs in that only one specific restriction enzyme (TspRI) is used. The cohesive ends of the DNA fragments are ligated with two types of oligonucleotide. A long oligonucleotide containing the primer site and the specific 9 nt 3 prime end, which is complementary to specific 9 nt, cohesive 3 prime end of the TspRI genomic DNA fragment, and a short, degenerated, oligonucleotide covering the remaining TspRI cohesive ends. Other cohesive ends are covered by a short degenerated oligonucleotide lacking the primer site. The ligation mixture is used as a template for amplification using a single primer corresponding to the 5 prime end of the long, specific oligonucleotide. The selection of TspRI digested genomic DNA fragments for amplification is achieved by sequence selective ligation of the specific long oligonucleotide carrying the primer site to both ends of the specific target fragment. This technique allows for differentiation of the organisms without previous knowledge of their DNA sequence. The usefulness of the method is confirmed by genotyping of 70 previously characterized clinical E. coli isolates. The grouping obtained was identical to the results of REA‐PFGE. Versatility of the method is highlighted, i.e. its combining the advantages of the AFLP technique with a simple, rapid and cheap polymerase chain reaction product detection method. 相似文献
56.
Thomas Lewandowski Jianzhong Huang Frank Fan Shannon Rogers Daniel Gentry Reannon Holland Peter DeMarsh Kelly Aubart Magdalena Zalacain 《Antimicrobial agents and chemotherapy》2013,57(7):2929-2936
Inhibitors of peptide deformylase (PDF) represent a new class of antibacterial agents with a novel mechanism of action. Mutations that inactivate formyl methionyl transferase (FMT), the enzyme that formylates initiator methionyl-tRNA, lead to an alternative initiation of protein synthesis that does not require deformylation and are the predominant cause of resistance to PDF inhibitors in Staphylococcus aureus. Here, we report that loss-of-function mutations in FMT impart pleiotropic effects that include a reduced growth rate, a nonhemolytic phenotype, and a drastic reduction in production of multiple extracellular proteins, including key virulence factors, such as α-hemolysin and Panton-Valentine leukocidin (PVL), that have been associated with S. aureus pathogenicity. Consequently, S. aureus FMT mutants are greatly attenuated in neutropenic and nonneutropenic murine pyelonephritis infection models and show very high survival rates compared with wild-type S. aureus. These newly discovered effects on extracellular virulence factor production demonstrate that FMT-null mutants have a more severe fitness cost than previously anticipated, leading to a substantial loss of pathogenicity and a restricted ability to produce an invasive infection. 相似文献
57.
Krzysztof Szwed Wojciech Pawliszak Magdalena Szwed Marta Tomaszewska Lech Anisimowicz Alina Borkowska 《The Journal of thoracic and cardiovascular surgery》2021,161(4):1275-1282.e4
BackgroundNeuropsychiatric complications of surgical coronary revascularization are inconspicuous but frequent and clinically relevant. So far, attempts to reduce their occurrence, such as the introduction of off-pump coronary artery bypass (OPCAB) grafting method, have not brought the desired results. The aim of this trial was to determine whether using any of the 2 selected modifications of OPCAB could decrease the incidence of these undesired sequelae.MethodsIn this single-center, assessor- and patient-blinded, superiority, randomized controlled trial, 192 patients scheduled for elective isolated OPCAB were randomized to 3 parallel arms. The control arm underwent “conventional” OPCAB with vein grafts. The first study arm underwent anaortic OPCAB (ANA) with total arterial revascularization. The second study arm underwent OPCAB with vein grafts using carbon dioxide surgical field flooding (CO2FF). Outcomes included the incidence of postoperative delirium (PD) and early postoperative cognitive dysfunction (ePOCD).ResultsThe incidence of PD was 35.9% in the control (OPCAB) arm, 32.8% in the CO2FF arm, and 12.5% in the ANA arm (χ2 [2, N = 191] = 10.17; P = .006). Post hoc tests revealed that the incidence of PD in the ANA arm differed from that in the OPCAB arm (odds ratio [OR], 0.26; 95% confidence interval [CI], 0.09-0.68; P = .002). The incidence of ePOCD was 34.4% in the OPCAB arm, 28.1% in the CO2FF arm, and 9.5% in the ANA arm (χ2 [2, N = 191] = 11.58; P = .003). Post hoc tests revealed that the incidence of ePOCD differed between the ANA and OPCAB arms (OR, 0.20; 95% CI, 0.06-0.58; P < .001).ConclusionsPerforming ANA significantly decreases the incidence of PD and ePOCD compared with “conventional” OPCAB with vein grafts, whereas CO2FF is inconsequential in this regard. These results, which probably reflect decreased delivery of embolic load to the brain in ANA, may have practical applicability in daily practice to improve clinical outcomes. 相似文献
58.
59.
60.