全文获取类型
收费全文 | 18067篇 |
免费 | 1508篇 |
国内免费 | 37篇 |
专业分类
耳鼻咽喉 | 128篇 |
儿科学 | 692篇 |
妇产科学 | 523篇 |
基础医学 | 2312篇 |
口腔科学 | 232篇 |
临床医学 | 2048篇 |
内科学 | 3412篇 |
皮肤病学 | 305篇 |
神经病学 | 1972篇 |
特种医学 | 298篇 |
外国民族医学 | 5篇 |
外科学 | 1946篇 |
综合类 | 144篇 |
一般理论 | 67篇 |
预防医学 | 2734篇 |
眼科学 | 264篇 |
药学 | 1144篇 |
1篇 | |
中国医学 | 38篇 |
肿瘤学 | 1347篇 |
出版年
2024年 | 43篇 |
2023年 | 281篇 |
2022年 | 485篇 |
2021年 | 912篇 |
2020年 | 552篇 |
2019年 | 755篇 |
2018年 | 860篇 |
2017年 | 613篇 |
2016年 | 628篇 |
2015年 | 692篇 |
2014年 | 901篇 |
2013年 | 1149篇 |
2012年 | 1592篇 |
2011年 | 1610篇 |
2010年 | 824篇 |
2009年 | 664篇 |
2008年 | 1132篇 |
2007年 | 1194篇 |
2006年 | 960篇 |
2005年 | 894篇 |
2004年 | 808篇 |
2003年 | 723篇 |
2002年 | 536篇 |
2001年 | 70篇 |
2000年 | 54篇 |
1999年 | 58篇 |
1998年 | 110篇 |
1997年 | 75篇 |
1996年 | 37篇 |
1995年 | 48篇 |
1994年 | 40篇 |
1993年 | 39篇 |
1992年 | 28篇 |
1991年 | 17篇 |
1990年 | 15篇 |
1989年 | 20篇 |
1987年 | 9篇 |
1986年 | 14篇 |
1985年 | 17篇 |
1984年 | 15篇 |
1983年 | 6篇 |
1982年 | 10篇 |
1981年 | 14篇 |
1980年 | 13篇 |
1978年 | 5篇 |
1977年 | 9篇 |
1976年 | 5篇 |
1975年 | 7篇 |
1974年 | 8篇 |
1961年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Differences in blood pregnenolone and dehydroepiandrosterone levels between schizophrenia patients and healthy subjects. 总被引:1,自引:0,他引:1
Michael Ritsner Rachel Maayan Anatoly Gibel Abraham Weizman 《European neuropsychopharmacology》2007,17(5):358-365
BACKGROUND AND OBJECTIVE: Contradictory and confusing reports on serum dehydroepiandrosterone (DHEA) levels in schizophrenia led us to compare the serum concentration of its precursor, pregnenolone (PREG), between medicated schizophrenia patients and healthy subjects. The neurosteroid levels were monitored for two months and the relationship of these neurosteroids with schizophrenic symptomatology, emotional distress, and anxiety was examined. METHOD: We determined blood levels of PREG, and DHEA in 15 schizophrenia patients and 12 healthy controls at four time points: at the start of the study, after 2, 4 and 8 weeks. Analysis of covariance and canonical correlations across four time points were applied. RESULTS: Controlling for age, serum concentrations of PREG were lower, while the DHEA level and the molar ratio values of DHEA/PREG were higher in schizophrenia patients compared to healthy controls. Both levels of PREG and DHEA and their molar ratio did not change significantly during the study's period either among schizophrenia patients or healthy controls. The blood levels of PREG appear to be associated with trait-anxiety scores in the schizophrenia patients, while associations of clinical symptoms with two neurosteroids did not reach a significant level when the confounding effect of emotional distress, and anxiety scores was controlled. CONCLUSION: Low serum pregnenolone concentrations in schizophrenia appear to be associated with trait-anxiety scores independent of symptoms. Further research into the role of pregnenolone in schizophrenia is warranted. 相似文献
32.
Kevin G Becker Insong J Lee James W Nagle Rachel D Canning Ameer M Gado Rosarelis Torres Mihael H Polymeropoulos Paul T Massa WilliamE Biddison Paul D Drew 《International journal of developmental neuroscience》1997,15(7):73
We describe a novel human zinc finger cNDA, C2H2-171. This cDNA represents an mRNA which encodes a protein of 484 amino acids and a calculated molecular weight of 54 kD. Four zinc finger-like domains are found in the C-terminal end of the protein. At the N-terminus, C2H2-171 contains a POZ/tramtrack-like domain similar to that found in the tumor associated zinc finger proteins LAZ-3/BCL-6 and PLZ-F, as well as in non-zinc finger proteins. C2H2-171 RNA is preferentially expressed in the brain, and increases during the course of murine development, with maximal expression in the adult. C2H2-171 RNA is differentially expressed in brain regions, with the highest level of expression in the cerebellum. C2H2-171 RNA was expressed at high levels in primary cerebellar granule cell neurons compared to astrocytes. The gene encoding C2H2-171 is highly conserved in vertebrates, and maps to the terminus of human chromosome 1 (1q44-ter). This chromosomal location is associated with a number of cytogenetic aberrations including those involving brain developmental anomalies and tumorigenesis. These data suggest that C2H2-171 may play an important role in vertebrate brain development and function. 相似文献
33.
Ladenstein Ruth; Pearce Rachel; Hartmann Olivier; Patte Catherine; Goldstone Tony; Philip Thierry 《Blood》1997,90(8):2921-2930
34.
35.
Suresh Kumar Masilamani Annamalai Rachel Buckingham John Cashman 《Journal of children's orthopaedics》2007,1(2):107-113
The treatment of Legg-Calvé-Perthes disease remains controversial. The aim of this survey was to ascertain the current management
strategies of this condition amongst UK paediatric orthopaedic surgeons, with particular regard to containment procedures
in the fragmentation phase. Questionnaires were distributed at the January 2006 meeting of the British Society for Children’s
Orthopaedic Surgery (BSCOS) and was posted to all absent members. The results showed a great deal of variability not only
in the treatment of Perthes disease, but also in the decision-making processes. Consideration must now be given to a carefully
constructed national multi-centre prospective randomised controlled study into the optimum management of this disease 相似文献
36.
Rachel M Massey Oliver J Warren Michal Szczeklik Sophie Wallace Daniel R Leff John Kokotsakis Ara Darzi Thanos Athanasiou 《Journal of cardiothoracic surgery》2007,2(1):26-9
The use of a skeletonized internal thoracic artery in coronary artery bypass graft surgery has been shown to confer certain
advantages over a traditional pedicled technique, particularly in certain patient groups. Recent reports indicate that radial
and gastroepiploic arteries can also be harvested using a skeletonized technique. The aim of this study is to systematically
review the available evidence regarding the use of skeletonized radial and gastroepiploic arteries within coronary artery
bypass surgery, focusing specifically on it's effect on conduit length and flow, levels of endothelial damage, graft patency
and clinical outcome. Four electronic databases were systematically searched for studies reporting the utilisation of the
skeletonization technique within coronary revascularisation surgery in humans. Reference lists of all identified studies were
checked for any missing publications. There appears to be some evidence that skeletonization may improve angiographic patency,
when compared with pedicled vessels in the short to mid-term. We have found no suggestion of increased complication rates
or increased operating time. Skeletonization may increase the length of the conduit, and the number of sequential graft sites,
but no clear clinical benefits are apparent. Our study suggests that there is not enough high quality or consistent evidence
to currently advocate the application of this technique to radial or gastroepiploic conduits ahead of a traditional pedicled
technique. 相似文献
37.
38.
39.
Limb asymmetries in landing and jumping 2 years following anterior cruciate ligament reconstruction. 总被引:1,自引:0,他引:1
Mark V Paterno Kevin R Ford Gregory D Myer Rachel Heyl Timothy E Hewett 《Clinical journal of sport medicine》2007,17(4):258-262
OBJECTIVE: Female athletes who are at increased risk for anterior cruciate ligament (ACL) injury demonstrate biomechanical differences between limbs during athletic tasks that may persist following anterior cruciate ligament reconstruction (ACLR). This may limit an athlete's potential for safe return to sports competition. The purpose of this study was to determine if female athletes demonstrate lower limb asymmetries in landing and takeoff force following ACLR and clearance for return to competitive sports participation. We hypothesized that females following ACLR would demonstrate side-to-side differences in landing and jumping kinetics after their return to sport (2+ years) that would not be observed in a group of healthy female controls. DESIGN: Case control study. SETTING: The Sports Medicine Biodynamics Center at Cincinnati Children's Hospital Medical Center. PATIENTS: Fourteen female athletes at a mean of 27 months following ACLR and 18 healthy female athletes participated in the study. ASSESSMENT: All subjects executed a drop vertical jump (DVJ) task onto 2 force plates. Vertical ground reaction force (VGRF) was measured during landing and takeoff and was used to calculate landing phase loading rates. A 2-way analysis of variance was used to determine differences between the involved, uninvolved, and control limbs. RESULTS: Females who had undergone ACLR demonstrated increased VGRF (P = 0.001) and loading rate (P < 0.001) on the uninvolved limb during landing when compared with the involved limb and the control group. During takeoff, the involved limb showed significantly less ability to generate force (P = 0.03) than the uninvolved limb and the control limbs. CONCLUSIONS: Female athletes who have undergone ACLR and returned to sport may continue to demonstrate biomechanical limb asymmetries 2 years or more after reconstruction that can be identified during landing. 相似文献
40.
Becker Kavin G.; Nagle James W.; Canning Rachel D.; Biddison William E.; Ozato Keiko; Drew Paul D. 《Human molecular genetics》1995,4(4):685-691
C2H2-type zinc finger genes comprise one of the largest genefamilies in the human genome. These proteins are involved ingenetic regulation and development and are quite conserved throughoutevolution. The finger domains commonly contain the small linkerpeptide TGEKP between some finger units. Here, we report theisolation of 133 human zinc finger cDNAs, of which 118 are novel.These clones were isolated from human brain cDNA libraries usingoligonucleotide hybridization followed by expressed sequencetag (EST) analysis, sequencing from the conserved linker regionusing degenerate oligonucleotide primers. This directed partialsequencing approach to cDNA isolation and characterization,signature sequencing, combines the speed of EST automatic sequencingwith the focus of specific cDNA family analysis. Signature sequencingminimizes the generation of less informative random EST sequencesand provides a unique relative position for sequence comparison.We also show that there is an even distribution of these RNA5from this brain cDNA library, and that these cDNAs contain N-terminaldomains found in other zinc finger genes. This rapid focusedsequencing approach should be applicable to any family of cDNAscontaining short conserved signature peptide sequences. 相似文献