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   31735篇
  免费   2341篇
  国内免费   472篇
耳鼻咽喉   634篇
儿科学   532篇
妇产科学   680篇
基础医学   4480篇
口腔科学   490篇
临床医学   2618篇
内科学   7179篇
皮肤病学   964篇
神经病学   2180篇
特种医学   1755篇
外科学   4267篇
综合类   556篇
一般理论   15篇
预防医学   1291篇
眼科学   932篇
药学   2767篇
中国医学   340篇
肿瘤学   2868篇
  2023年   175篇
  2022年   343篇
  2021年   993篇
  2020年   499篇
  2019年   821篇
  2018年   953篇
  2017年   683篇
  2016年   908篇
  2015年   1239篇
  2014年   1466篇
  2013年   1685篇
  2012年   2453篇
  2011年   2531篇
  2010年   1531篇
  2009年   1318篇
  2008年   1855篇
  2007年   1766篇
  2006年   1603篇
  2005年   1532篇
  2004年   1281篇
  2003年   1251篇
  2002年   1138篇
  2001年   763篇
  2000年   684篇
  1999年   648篇
  1998年   270篇
  1997年   264篇
  1996年   226篇
  1995年   193篇
  1994年   173篇
  1993年   116篇
  1992年   309篇
  1991年   241篇
  1990年   269篇
  1989年   280篇
  1988年   258篇
  1987年   214篇
  1986年   186篇
  1985年   172篇
  1984年   145篇
  1983年   121篇
  1982年   88篇
  1981年   82篇
  1980年   75篇
  1979年   127篇
  1978年   84篇
  1977年   69篇
  1975年   60篇
  1974年   53篇
  1972年   49篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
201.
The present study has been designed to: (1) evaluate the adequacy of a psychosocial-appraisal health model posited to explain the decision-making processes associated with the intention as well as the (non)practice of protective behaviours; and (2) test for sex differences in the hypothesized structural relations (both direct and indirect) between the model's exogenous (psychosocial) and endogenous (cognitive appraisal) factors in representing the way health decisions are made. Results obtained from path analysis (N=1269) provided overall support for the 'fit' of the hypothesized health model. The implications of the findings with regard to differences in male and female health status are discussed.  相似文献   
202.
203.
Oh SH  Kang SG  Kim ES  Cho SH  Lee JH 《Biomaterials》2003,24(22):4011-4021
Porous PLGA/PVA scaffolds were fabricated by blending poly(lactic-co-glycolic acid) (PLGA) with polyvinyl alcohol (PVA) to improve the hydrophilicity and cell compatibility of the scaffolds for tissue engineering applications. PLGA/PVA blend scaffolds with different PVA compositions up to 20wt% were fabricated by a melt-molding particulate-leaching method (non-solvent method). The prepared scaffolds were investigated by scanning electron microscopy (SEM), mercury intrusion porosimetry, the measurements of water contact angles and bi-axial tensile strengths, etc. for their surface and bulk characterizations. The scaffolds exhibited highly porous and open-cellular pore structures with almost same surface and interior porosities (pore size, 200-300 microm; porosity, about 90%). The PLGA/PVA blend scaffolds with PVA compositions more than 5% were easily wetted in cell culture medium without any prewetting treatments, which is highly desirable for tissue engineering applications. In vitro cell compatibility of the control hydrophobic PLGA and hydrophilized PLGA/PVA (5wt%) blend scaffolds was compared by the culture of human chondrocytes in the scaffolds and the following analyses by MTT assay and SEM observation. It was observed that the PLGA/PVA blend scaffold had better cell adhesion and growth than the control PLGA scaffold. For in vivo evaluation of tissue compatibility, the scaffolds were implanted into the skull defects of rabbits. The results were evaluated by histology examinations. The PLGA/PVA (5wt%) blend scaffold showed better bone ingrowth into the scaffold and new bone formation inside the scaffold than the PLGA scaffold. It seems that 5% addition of PVA to PLGA to fabricate PLGA/PVA blend scaffolds is enough for improving the hydrophilicity and cell compatibility of the scaffolds.  相似文献   
204.
Clostridium botulinum neurotoxins (BoNTs) are the most toxic proteins for humans. The current clostridial-derived vaccines against BoNT intoxication have limitations including production and accessibility. Conditions were established to express the soluble receptor binding domain (heavy-chain receptor [HCR]) of BoNT serotypes A and E in Escherichia coli. Sera isolated from mice and rabbits immunized with recombinant HCR/A1 (rHCR/A1) from the classical type A-Hall strain (ATCC 3502) (BoNT/A1) and rHCR/E from BoNT serotype E Beluga (BoNT/E(B)) neutralized the homologous serotype of BoNT but displayed differences in cross-recognition and cross-protection. Enzyme-linked immunosorbent assay and Western blotting showed that alpha-rHCR/A1 recognized epitopes within the C terminus of the HCR/A and HCR/E, while alpha-rHCR/E recognized epitopes within the N terminus or interface between the N and C termini of the HCR proteins. alpha-rHCR/E(B) sera possessed detectable neutralizing capacity for BoNT/A1, while alpha-rHCR/A1 did not neutralize BoNT/E. rHCR/A was an effective immunogen against BoNT/A1 and the Kyoto F infant strain (BoNT/A2), but not BoNT serotype E Alaska (BoNT/E(A)), while rHCR/E(B) neutralized BoNT/E(A), and under hyperimmunization conditions protected against BoNT/A1 and BoNT/A2. The protection elicited by rHCR/A1 to BoNT/A1 and BoNT/A2 and by rHCR/E(B) to BoNT/E(A) indicate that immunization with receptor binding domains elicit protection within sub-serotypes of BoNT. The protection elicited by hyperimmunization with rHCR/E against BoNT/A suggests the presence of common neutralizing epitopes between the serotypes E and A. These results show that a receptor binding domain subunit vaccine protects against serotype variants of BoNTs.  相似文献   
205.
This study analyzed the expression of anti-islet autoantibodies and HLA-DR and -DQ genotypes in Korean children with type 1 diabetes mellitus (T1DM). The positivity of the anti-ICA512, anti-GAD65, and anti-insulin autoantibodies in the newly onset T1DM patients (n = 15) was 66.7%, 86.7%, and 46.7%, respectively, and all of them had one or more of the autoantibodies. HLA analysis showed higher frequencies of HLA-DRB1*0301, *0405, *09012 and -DQB1*0201, *0401, *03032 alleles in T1DM patients compared to controls (P(c) < 0.05). Because HLA-DQB1*0401, *03032 alleles carry aspartic acid at position 57 of DQB, susceptibility to T1DM in Korean children was not related to the presence of aspartic acid at position 57 of DQB1 locus. We suggest this unique HLA-DR, -DQ allele distribution might be an important factor for the low incidence of T1DM in Korea, and the combined anti-islet autoantibody assays could be valuable screening markers for the early detection of T1DM in Korea.  相似文献   
206.

Objectives

Automated point-of-care molecular assays have greatly shortened the turnaround time of respiratory virus testing. One of the major bottlenecks now lies at the specimen collection step, especially in a busy clinical setting. Saliva is a convenient specimen type that can be provided easily by adult patients. This study assessed the diagnostic validity, specimen collection time and cost associated with the use of saliva.

Methods

This was a prospective diagnostic validity study comparing the detection rate of respiratory viruses between saliva and nasopharyngeal aspirate (NPA) among adult hospitalized patients using Xpert® Xpress Flu/RSV. The cost and time associated with the collection of saliva and nasopharyngeal specimens were also estimated.

Results

Between July and October 2017, 214 patients were recruited. The overall agreement between saliva and NPA was 93.3% (196/210, κ 0.851, 95% CI 0.776–0.926). There was no significant difference in the detection rate of respiratory viruses between saliva and NPA (32.9% (69/210) versus 35.7% (75/210); p 0.146). The overall sensitivity and specificity were 90.8% (81.9%–96.2%) and 100% (97.3%–100%), respectively, for saliva, and were 96.1% (88.9%–99.2%) and 98.5% (94.7%–99.8%), respectively, for NPA. The time and cost associated with the collection of saliva were 2.26-fold and 2.59-fold lower, respectively, than those of NPA.

Conclusions

Saliva specimens have high sensitivity and specificity in the detection of respiratory viruses by an automated multiplex Clinical Laboratory Improvement Amendments-waived point-of-care molecular assay when compared with those of NPA. The use of saliva also reduces the time and cost associated with specimen collection.  相似文献   
207.
208.

Objective

To review observational human, murine, and interventional trial studies that have examined the gut microbiome in food allergy, and to provide perspective on future investigations in this field.

Data Sources

A review of the published literature was performed with PubMed, and clinical studies catalogued at ClinicalTrials.gov were also reviewed.

Study Selections

The most recent relevant studies, seminal works, and topical clinical trials were selected.

Results

Gut dysbiosis likely precedes the development of food allergy, and the timing of such dysbiosis is critical. Gut microbiota associated with individual food allergies may be distinct. Murine models support the importance of gut microbiota in shaping immune maturation and tolerance. Gut microbiota may affect food allergy susceptibility by modulating type 2 immunity, influencing immune development and tolerance, regulating basophil populations, and promoting intestinal barrier function. Ongoing and future interventional trials of probiotics, prebiotics, synbiotics, and fecal microbiota transfer will help translate our understanding of the gut microbiome in food allergy to clinical practice. Future work in this area will include deepening of current research foci, as well as expansion of efforts to include the virome, mycobiome, and interactions between the microbiome, host, and environment. Robust and consistent study designs, multidimensional profiling, and systems biology approaches will enable this future work.

Conclusion

By advancing research on the microbiome in food allergy, we can further our understanding of food allergy and derive new approaches for its prevention and therapy.  相似文献   
209.
The present study was performed to determine whether the effects induced by GABA(B) receptor-acting drugs would be related with the alteration in GABA(B) receptor expression in the hippocampus using Mongolian gerbil, a genetic epilepsy model. The distribution patterns of both GABA(B) receptor 1A/B and GABA(B)receptor 2 immunoreactivities were similarly detected in the hippocampi of normal and seizure-prone gerbils. Following baclofen (GABA(B) receptor agonist) or phaclofen (GABA(B) receptor antagonist) treatment, GABA(B) receptor immunoreactivities were decreased or increased by dose-dependent manners, respectively. Vigabatrin (GABA transaminase inhibitor) or 3-mercaptopropionic acid (GAD inhibitor) treatment did not affect GABA(B) receptor expressions. These findings suggest that GABA(B) receptor expression in the gerbil hippocampus may be altered by baclofen or phaclofen treatment.  相似文献   
210.
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