首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   803565篇
  免费   55605篇
  国内免费   2037篇
耳鼻咽喉   10450篇
儿科学   27514篇
妇产科学   22722篇
基础医学   116440篇
口腔科学   22110篇
临床医学   72447篇
内科学   155220篇
皮肤病学   18266篇
神经病学   63499篇
特种医学   30792篇
外国民族医学   234篇
外科学   119476篇
综合类   19023篇
一般理论   295篇
预防医学   62184篇
眼科学   18034篇
药学   57609篇
  16篇
中国医学   1595篇
肿瘤学   43281篇
  2018年   8566篇
  2017年   6651篇
  2016年   7521篇
  2015年   8401篇
  2014年   11626篇
  2013年   17502篇
  2012年   23044篇
  2011年   24555篇
  2010年   14721篇
  2009年   13860篇
  2008年   23107篇
  2007年   24375篇
  2006年   24686篇
  2005年   23834篇
  2004年   23121篇
  2003年   22142篇
  2002年   21439篇
  2001年   37564篇
  2000年   38432篇
  1999年   32374篇
  1998年   8945篇
  1997年   8085篇
  1996年   8196篇
  1995年   7855篇
  1994年   7258篇
  1993年   6729篇
  1992年   25770篇
  1991年   25185篇
  1990年   24950篇
  1989年   23926篇
  1988年   21781篇
  1987年   21758篇
  1986年   20372篇
  1985年   19601篇
  1984年   14631篇
  1983年   12384篇
  1982年   7391篇
  1981年   6646篇
  1979年   13533篇
  1978年   9740篇
  1977年   8229篇
  1976年   7839篇
  1975年   8096篇
  1974年   9880篇
  1973年   9516篇
  1972年   8697篇
  1971年   8012篇
  1970年   7552篇
  1969年   6993篇
  1968年   6534篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
The measures for leishmaniasis control include the precise diagnosis of disease. However, although several recombinant antigens have been tested with this biotechnological purpose, no effective product exists, which could detects patients with the active disease, as well as differentiates them from cured and treated patients. In this study, a conserved Leishmania hypothetical protein, which was identified in Leishmania infantum parasites, but evaluated to presents high homology in the amino acid sequences between distinct parasite species, was evaluated for the diagnosis of tegumentary and visceral leishmaniasis. In addition, PBMCs collected from treated and untreated mucosal leishmaniasis (ML) and visceral leishmaniasis (VL) patients, as well as in healthy subjects living in endemic region of disease, were in vitro stimulated, when IFN-γ, IL-4 and IL-10 levels were evaluated in the cell supernatant. Regarding the serological analyses, ELISA experiments using the recombinant protein (rLiHyL) and a human serological panel revealed high sensitivity and specificity values to detect both diseases, while control antigens showed worst results. Regarding the cellular response, results showed that rLiHyL-stimulated cells produced higher IFN-γ and lower IL-4 and IL-10 levels in the supernatants. Also, the anti-protein antibody production was evaluated in these patients, and data showed higher IgG2 and lower IgG1 levels found in the treated patients and healthy controls, demonstrating the stimulation of a Th1-type response induced by the rLiHyL protein. In conclusion, this hypothetical protein can be considered as antigenic in TL and VL, as well as a vaccine candidate to be tested in future studies to protect against disease.  相似文献   
72.
Neuroscience and Behavioral Physiology - We report here a comparative (using chemical, electrical, and optical stimulation) study of the electrophysiological properties of cultured hippocampal...  相似文献   
73.
Current models describing HLA epitopes are both theoretical and empirical. Each has limitations yielding discordant results and increasingly complex modeling. The models make a priori assumptions that epitopes must be present only on the mature protein, solvent accessible, on the ‘top’ (peptide binding surface) of the molecule, restricted to the same class as the antibody, and in the same position on the target allele if reactive to more than one locus. Results obtained counter to these assumptions are routinely discounted. For the 17th International Histocompatibility and Immunogenetics Workshop, we developed a reverse engineering algorithm to define epitopes without these assumptions on a cohort of 332 primary transplant pairs. Complete NGS typing of the transcribed (including leader) genomic DNA for 11 HLA loci of donor and recipient and DSA assignment by single antigen beads was performed. Our results show that, when grouped by 16 class I and II allele specific DSA, uniform clusters and 172 specific amino acid target epitopes are recognized by recipients despite originating from disparate HLA pairs. Data also show that these targets can be in the leader, alpha 3, transmembrane and cytoplasmic domains, thus calling into question current assumptions regarding immunogenic epitopes. Comparisons of amino acid epitopes defined by the Terasaki and Duquesnoy groups (TerEp and EpRegistry) are given.  相似文献   
74.
Neuroscience and Behavioral Physiology - Objective. To study the association between single-nucleotide polymorphisms (SNP) of the RORA (rs1159814), CLOCK (rs12649507), PER3 (rs2640909), NPSR1...  相似文献   
75.
Neuroscience and Behavioral Physiology - The aim of the present work was to identify the role of stretch-activated ion channels (SAC) in the transmission of mechanical signals to the key...  相似文献   
76.
BackgroundThere is a lack of objective dynamic knee joint control measures that can be related to the status of the anterior cruciate ligament (ACL). The purpose of this study was to introduce two novel measures and apply a third to determine how dynamic knee joint control changes in relation to ACL status during dynamic movements.MethodsTwenty patients (13 male) were tested pre- (ACLd) and 10-months post- (ACLr) ACL reconstructive surgery and matched to an uninjured participant (CON). Kinetic and kinematic data were synchronously recorded with a force platform and motion capture system. Three objective control measures including dynamic angular stiffness, knee joint center excursion (KJCE), and knee joint center boundary (KJCB) were assessed for each participant when completing the side cut and hop tasks.ResultsDuring the side cut, stiffness was found to be significantly lower in ACLd (0.06 ± 0.01 Nm/kg/°) and ACLr (0.07 ± 0.02 Nm/kg/°) compared to CON (0.08 ± 0.02 Nm/kg/°), while there were no differences in stiffness during the hop. No significant differences were observed in the KJCE during the side cut, while KJCE was significantly greater (p = 0.006) during the hop in CON compared to the ACLd. There were no differences in KJCB.ConclusionsThese high-functioning ACL injured in both ACLd and ACLr phases, aside from reduced stiffness, were able to complete both tasks with similar dynamic control as the CON. Although improvements in self-perceived control between ACLd and ACLr have been observed, this lack of improvement in objective control demonstrates a gap between a patient's self-efficacy and the level of control.  相似文献   
77.

A total of 482 bats representing 32 species and two families were captured in the Amazon forests of the Amapá state in northern Brazil. Nineteen Artibeus planirostris bats (3.9 %) were infested with 160 ticks, all identified as Ornithodoros hasei. Three pools of larvae were screened for rickettsial DNA via polymerase chain reaction (PCR) targeting three rickettsial genes: gltA, ompA and htrA. Only one of them yielded an amplicons of the expected size for all three molecular assays. Comparisons of the obtained sequences including a phylogenetic analysis confirmed the occurrence of “Candidatus Rickettsia wissemanii” in Brazil.

  相似文献   
78.
Frequently, patients receiving parenteral nutrition (PN) report hunger during the parenteral infusion, yet experience early satiety once PN is tapered off. Post-PN satiety can interfere with the ability to consume enough nutrients to maintain body weight and nutritional status. Factors such as caloric quantity of infusate, gastric motility changes, and disease pathology have been related to appetite changes. To investigate the effects of PN on food intake and gastric motility without the complicated interactions associated with disease pathology, four normal, healthy rhesus monkeys (Macaca mulatta) were studied. The monkeys were administered PN in amounts ranging from 25% to 100% of their normal daily caloric intake. Food and water were continuously available. PN consistently suppressed voluntary food intake in direct relationship to the amount of nutrient infused. The frequency of large-amplitude hunger-type gastric contractions decreased from control conditions. Upon cessation of PN, appetite remained suppressed for one to two weeks, indicating a self-limiting physiological basis to post-PN satiety. Thus, reduced appetite following PN termination might occur in the clinical setting and the patients' feelings of satiety may not be completely attributed to lack of cooperation or disease pathology.  相似文献   
79.
Faunal health is largely dependent on their soil environment and available litter quality. So the effects of different soil habitats and pesticides on citrate synthase (CS) activity of soil fauna and its population were studied. Methods The soil animals were collected from different pedoecosystems for habitat study. Whereas Vigna radiata based system was selected for pesticidal observations. The field was divided into five equal plots for control and treatment of γ-BHC, quinalphos, carbaryl and cypermethrin. Soil fauna was collected by quadrat method and extracted by Tullgren funnel. Individuals of a species having similar sizes were collected for the estimation of CS activity. They were homogenized and fractions were obtained by differential centrifugation. The activity of CS was assayed spectrophotometrically. Results Citrate synthase (CS) activity of beetle (Rasphytus fregi), woodlouse (PorceUio laevis) and centipede (Scolopendra morsitans) varied significantly with respect to changes in different soil habitats. Though the CS activity of R. fregi, P. laevis, and S. morsitans differed among themselves but the highest activity of CS in these animals was in V. radiata and lowest in A. nilotica based pedoecosystem. The aerobic capacity of centipede was maximum followed by woodlouse and beetle. The treatment of γ-BHC, quinalphos, carbaryl and cypermethrin significantly reduced the CS activity of these animals. γ-BHC showed maximum reduction in CS activity indicating highly toxic effect of organochlorine on aerobic metabolism of soil fauna. However, minimum reduction was obseryed in response to carbaryl (in beetle) or cypermethrin (in woodlouse/centipede) leading to impairment of aerobic capacity. The differences in pesticide effects might be assigned to the differences in chemical nature of pesticides and their interactions with below-ground fauna. Treatment ofγ-BHC and quinalphos reduced the population of Acari, Coleoptera, Collembola, other arthropods as well as total soil fauna. Acari was least affected by γ-BHC and maximally affected (72%) in response to quinalphos. The effect of γ-BHC was fairly similar on Coleoptera, Collembola, other arthropod and total soil fauna suggesting almost similar sensitivity to this pesticide. Likewise, quinalphos was similarly effective on Collemobola and other soil arthropods. Application of carbaryl decreased Acari and Coleoptera population but increased Collembola, other arthropods and total faunal populations. However, application of cypermethrin significantly reduced the population of Acari, Coleoptera, Collembola and total soil fauna and increased the population of other soil arthropods. In both the cases, acarine population was least affected. Conclusion The observations show the habitat-specific variation in aerobic capacity of soil fauna. However, pesticide-dependent loss in population might be due to impairment of aerobic capacity of soil inhabiting animals in desert.  相似文献   
80.
International Journal of Clinical Pharmacy - Background The role of pharmacists in medication reconciliation (MedRec) is highly acknowledged in many developed nations. However, the impact of this...  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号