全文获取类型
收费全文 | 220645篇 |
免费 | 8521篇 |
国内免费 | 487篇 |
专业分类
耳鼻咽喉 | 3062篇 |
儿科学 | 6440篇 |
妇产科学 | 5659篇 |
基础医学 | 31669篇 |
口腔科学 | 6964篇 |
临床医学 | 12969篇 |
内科学 | 48755篇 |
皮肤病学 | 6115篇 |
神经病学 | 17689篇 |
特种医学 | 5721篇 |
外国民族医学 | 2篇 |
外科学 | 25426篇 |
综合类 | 1037篇 |
一般理论 | 40篇 |
预防医学 | 25504篇 |
眼科学 | 5758篇 |
药学 | 17242篇 |
中国医学 | 840篇 |
肿瘤学 | 8761篇 |
出版年
2023年 | 1094篇 |
2022年 | 823篇 |
2021年 | 3368篇 |
2020年 | 1866篇 |
2019年 | 3819篇 |
2018年 | 6582篇 |
2017年 | 4093篇 |
2016年 | 4052篇 |
2015年 | 4579篇 |
2014年 | 5096篇 |
2013年 | 7941篇 |
2012年 | 13364篇 |
2011年 | 13936篇 |
2010年 | 7091篇 |
2009年 | 5215篇 |
2008年 | 11485篇 |
2007年 | 12308篇 |
2006年 | 11881篇 |
2005年 | 11500篇 |
2004年 | 10691篇 |
2003年 | 9980篇 |
2002年 | 9558篇 |
2001年 | 6800篇 |
2000年 | 7474篇 |
1999年 | 5805篇 |
1998年 | 1140篇 |
1992年 | 3060篇 |
1991年 | 2758篇 |
1990年 | 2688篇 |
1989年 | 2376篇 |
1988年 | 2230篇 |
1987年 | 2126篇 |
1986年 | 2119篇 |
1985年 | 1963篇 |
1984年 | 1427篇 |
1983年 | 1222篇 |
1979年 | 1617篇 |
1978年 | 1041篇 |
1977年 | 975篇 |
1976年 | 950篇 |
1975年 | 1139篇 |
1974年 | 1505篇 |
1973年 | 1491篇 |
1972年 | 1385篇 |
1971年 | 1337篇 |
1970年 | 1326篇 |
1969年 | 1377篇 |
1968年 | 1396篇 |
1967年 | 1237篇 |
1966年 | 1082篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
Huisman JA; Paulussen RJ; Geurts TB; Odink J; Rekers H 《Human reproduction (Oxford, England)》1997,12(1):34-38
The objective was to demonstrate bioequivalence between s.c. and i.m.
administration of Humegon (FSH/LH ratio 1:1) and Normegon (FSH/LH ratio
3:1). In two randomized, single-centre, cross-over studies, 18 healthy
volunteers on each formulation were assigned to one of the two
administration sequences. Subjects were given single doses of one of the
above gonadotrophins after endogenous gonadotrophin production had first
been suppressed using high-dose oral contraceptive. Subsequently, rate
(Cmax, tmax) and extent (AUC) of absorption of follicle stimulating hormone
(FSH) and luteinizing hormone (LH) were determined for 14 days. For Cmax
and AUC, analysis of variance (ANOVA) was performed on log-transformed data
and for tmax ANOVA was performed on ranks. Intramuscular and s.c.
injections of Humegon were bioequivalent with respect to the main
pharmacokinetic parameters, being AUC and Cmax of FSH absorption.
Intramuscular and s.c. injections of Normegon were bioequivalent with
respect to the AUC of FSH and not bioequivalent with respect to the Cmax of
FSH. For tmax of FSH as well as for most LH variables of both preparations,
bioequivalence could not be proven due to the high intra- and
interindividual variability and/or concentrations being close to the
detection limit. Thus, the main pharmacokinetic FSH variables after i.m.
and s.c. administration of Humegon and Normegon were bioequivalent.
相似文献
992.
993.
Pérez-Caballero D Albertí S Vivanco F Sánchez-Corral P Rodríguez de Córdoba S 《European journal of immunology》2000,30(4):1243-1253
Group A Streptococcus (GAS), the most frequent bacterial cause of suppurative infections in humans, expresses on the cell surface M proteins with capacity to bind factor H, FHL-1 and C4b binding protein (C4BP). This has been interpreted as a mechanism developed by this pathogen to decrease phagocytosis by macrophages and polymorphonuclear cells. We report the analysis of the capacity to bind factor H, FHL-1 and C4BP of 69 clinical isolates from 19 different serotypes. We show that strains binding complement regulators (30/69) belong to specific M serotypes. Of these, M18 strains are relatively frequent and interact with all three complement regulators simultaneously. However, the most virulent M1 and M3 strains did not bind complement regulators in our assays. The relevance of the interaction between complement regulators and S. pyogenes was analyzed using different approaches with the conclusion that under physiological conditions only FHL-1 and C4BP bind to streptococci. We show that FHL-1 presents a higher binding affinity for S. pyogenes than factor H because it carries a hydrophobic, high-affinity, GAS binding site in addition to the heparin binding site in SCR7. Using synthetic peptides we provide evidence that the high-affinity GAS binding site in FHL-1 involves the hydrophobic tail (Ser-Phe-Thr-Leu) that distinguishes FHL-1 from factor H. 相似文献
994.
Peyvandi F Tagliabue L Menegatti M Karimi M Komáromi I Katona E Muszbek L Mannucci PM 《Human mutation》2004,23(1):98
Factor XIII (FXIII) deficiency is a very rare severe autosomal bleeding disorder with a frequency of 1:2,000,000 in the general population and only a few patients have been genetically characterized so far. We report a phenotype-genotype characterization of 10 unrelated Iranian patients. Two FXIII (transglutaminase) activity assays showed no FXIII activity, except a conserved residual activity in patients receiving prophylactic substitution treatment. FXIII antigen concentrations measured by two immunoassays were comparable. Genotype characterization identified four novel mutations (2 missense and 2 small deletions) and two previously reported missense mutations in the FXIII A subunit gene (F13A). Molecular modeling was carried out to reveal the structural consequences of the missense mutations, that caused the replacement of an arginine residue involved in the formation of structurally important extensive hydrogen-bonded network. The replacements [c.320G>A (p.Arg77His) in the beta-sandwich, c.868C>T (p.Arg260Cys), c.869G>A (p.Arg260His) and c.1236G>T (p.Arg382Ser) in the core domain] resulted in the loss or impairment of such H-bonded network. Energy decomposition analysis demonstrated that this situation leads to the instability and perhaps to the incorrect folding of the A subunit, that would explain the development of severe FXIII deficiency. 相似文献
995.
Ticks are ectoparasites of wild and domestic animals and humans, and are considered to be the most important arthropod vector of pathogens in North America. Development of vaccines directed against tick proteins may effect reduction of tick infestations and transmission of tick-borne pathogens. The limiting step for the development of tick vaccines has been the identification of tick protective antigens. Reverse vaccinology approaches aimed at reducing animal experimentation while allowing for the rapid screening of pools of potential tick vaccine candidates would greatly facilitate progress towards the development of tick vaccines. Herein, we describe the screening of Ixodes scapularis cDNAs for identification of tick protective antigens using RNA interference (RNAi). The results of the RNAi screening were similar to those obtained previously using expression library immunization and demonstrated that RNAi could serve as a more rapid and cost-effective tool for vaccine antigen discovery in ticks and in other nonmodel organisms. 相似文献
996.
997.
998.
Iván Alvarez Anna Sureda Maria D Caballero Alvaro Urbano-Ispizua Josep M Ribera Miguel Canales Javier García-Conde Guillermo Sanz Reyes Arranz Maria T Bernal Javier de la Serna José L Díez José M Moraleda Daniel Rubió-Félix Blanca Xicoy Carmen Martínez Marivi V Mateos Jorge Sierra 《Biology of blood and marrow transplantation》2006,12(2):172-183
We report the results of reduced-intensity conditioning allogeneic stem cell transplantation (allo-RIC) in patients with advanced Hodgkin lymphoma (HL). Forty patients with relapsed or refractory HL were homogeneously treated with an RIC protocol (fludarabine 150 mg/m(2) intravenously plus melphalan 140 mg/m(2) intravenously) and cyclosporin A and methotrexate as graft-versus-host disease (GVHD) prophylaxis. Twenty-one patients (53%) had received >2 lines of chemotherapy, 23 patients (58%) had received radiotherapy, and 29 patients (73%) had experienced treatment failure with a previous autologous stem cell transplantation. Twenty patients (50%) were allografted in resistant relapse, and 38 patients received hematopoietic cells from an HLA-identical sibling. Five patients (12%) died from early transplant-related mortality (before day +100 after allo-RIC). One-year transplant-related mortality was 25%. Acute GVHD developed in 18 patients (45%). Chronic GVHD developed in 17 (45%) of the 31 evaluable patients. The response rate 3 months after the allo-RIC was 67% (21 [52%] complete remissions and 6 [15%] partial remissions). Eleven patients received donor lymphocyte infusions (DLIs) for disease relapse. The response rate after DLI was 54% (3 complete remissions and 3 partial remissions). Overall survival (OS) and progression-free survival (PFS) were 48% +/- 10% and 32% +/- 10% at 2 years, respectively. Refractoriness to chemotherapy was the only adverse prognostic factor for both OS (63% +/- 12% versus 35% +/- 13%; P = .05) and PFS (55% +/- 16% versus 10% +/- 9%; P = .006). For patients with failure of a prior autologous hematopoietic stem cell transplantation, results were especially good for those who experienced late relapses (>/=12 months: 2-year OS and PFS were 75% +/- 16% and 70% +/- 18%, respectively). These data suggest that allo-RIC is feasible in heavily pretreated HL patients and has an acceptable early transplant-related mortality. Results are better in patients allografted in sensitive disease. Both responses observed after the development of GVHD and DLI may suggest a graft-versus-HL effect. Allo-RIC has to be considered an effective therapeutic approach for patients who have had treatment failure with a previous autologous hematopoietic stem cell transplantation. 相似文献
999.
Summary Forty men were tested with a computerized dynamometer for concentric and eccentric torques during arm flexion and extension at 0.52, 1.57, and 2.09 rad·s–1. Based on the summed concentric and eccentric torque scores, subjects were placed into a high strength (HS) or low strength (LS) group. The eccentric and concentric segments of the torque-velocity curves (TVCs) were generated using peak torque and constant-angle torque (CAT) at 1.57 and 2.36 rad. Angle of peak torque was also recorded. Compared to LS, HS had significantly greater estimated lean body mass (+ 10.2 kg) and approximately 25% greater average torque output. Reliability of the peak torque scores on 2 days in 20 subjects wasr0.85. The difference between observed torques and the mathematically computed criterion torque scores averaged 1% for three validation loads that ranged from 11.4 to 90.4 kg. Statistical analysis revealed that torque output in LS plateaued at low concentric velocities and was also flattened with increasing eccentric velocities. Conversely, torque ouptput for HS increased with decreasing concentric velocities and increased with increasing eccentric velocities. The method of plotting the TVCs for peak or CAT did not influence the pattern of TVC. Eccentric flexion peak torque occurred at a significantly shorter muscle length (1.88 rad) than concentric torque (2.12 rad). This difference was also present for extension; it was 1.88 rad for eccentric and 2.03 rad for concentric torque. These findings are discussed in terms of study design, neural inhibition, activation history, muscle-tendon elasticity, muscle fiber types, muscle architecture, and methodological considerations. The present results illustrate the importance of strength level to explain individual differences in TVC. 相似文献
1000.
O J Castejón 《Journal of submicroscopic cytology and pathology》1990,22(1):123-134
The cerebellar Bergmann glial cells of Swiss albino mouse, teleost fish and human have been examined by means of freeze-fracture and ethanol-cryofracturing techniques for scanning electron microscopy and freeze-etching and thin sectioning techniques for transmission electron microscopy in order to study the outer surface, membrane morphology and topographic relationship with Purkinje cells, parallel and climbing fibers and stellate axons. Freeze-fracture and ethanol-cryofracturing techniques exposed the somatic outer surface and lamellated processes surrounding the Purkinje cells. Transmission electron microscopy showed a granular substance filling the extracellular space separating Bergmann glial cell cytoplasm from dark Purkinje cells. This substance was absent in the vicinity of clear Purkinje cells. Freeze-etching replicas showed a multilayered ensheathment of Bergmann glial lamellar processes surrounding parallel fibers. The P face of Bergmann glial cell plasma membrane exhibited orthogonal arrays or assemblies of intramembrane particles (IMPs) and high density distribution of round IMPs 6-15 nm in diameter, whereas the E face was characterized by a smooth surface and low density distribution of IMPs. Rod intramembrane particles, 20-30 nm in length, were also found in the plasma membrane P and E faces. The fractured Bergmann glial cell cytoplasm was observed encapsulating the parallel fiber varicosities, or the bundles of non-synaptic segments of parallel fibers and enclosing the climbing fiber and stellate axonal synapses with Purkinje dendrites. 相似文献