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   4581篇
  免费   283篇
  国内免费   28篇
耳鼻咽喉   44篇
儿科学   132篇
妇产科学   128篇
基础医学   794篇
口腔科学   75篇
临床医学   465篇
内科学   848篇
皮肤病学   157篇
神经病学   549篇
特种医学   148篇
外科学   326篇
综合类   42篇
一般理论   3篇
预防医学   347篇
眼科学   72篇
药学   397篇
中国医学   43篇
肿瘤学   322篇
  2023年   37篇
  2022年   89篇
  2021年   209篇
  2020年   107篇
  2019年   166篇
  2018年   146篇
  2017年   106篇
  2016年   150篇
  2015年   147篇
  2014年   212篇
  2013年   250篇
  2012年   430篇
  2011年   452篇
  2010年   252篇
  2009年   172篇
  2008年   341篇
  2007年   315篇
  2006年   269篇
  2005年   240篇
  2004年   201篇
  2003年   171篇
  2002年   157篇
  2001年   33篇
  2000年   21篇
  1999年   38篇
  1998年   31篇
  1997年   18篇
  1996年   10篇
  1995年   12篇
  1994年   14篇
  1993年   6篇
  1992年   5篇
  1991年   5篇
  1990年   5篇
  1988年   3篇
  1987年   3篇
  1986年   4篇
  1985年   3篇
  1984年   5篇
  1983年   4篇
  1982年   4篇
  1981年   5篇
  1980年   4篇
  1979年   5篇
  1978年   6篇
  1977年   3篇
  1975年   4篇
  1974年   5篇
  1971年   3篇
  1934年   2篇
排序方式: 共有4892条查询结果,搜索用时 15 毫秒
41.
In order to investigate the ameliorative potential of L-ascorbic acid on intensive swimming exercise induced testicular oxidative stress, 18 Wistar male rats (age: 3 months, weight: 127.5 ± 5.3 g) were randomly divided into the following groups: (i) control group (CG,n = 6); (ii) experimental group (EG,n = 6); and (iii) supplemented group (SG,n = 6). An exercise protocol of 3 h swimming per day, five days per week was followed for 6 weeks in EG and SG with no exercise in CG. In SG, L-ascorbic acid was supplied orally at a dose of 25-mg/kg of bodyweight each day for 6 weeks. A significant decrease (P < 0.05) was noted in paired testicular weights, epididymal sperm count, testicular Δ5, 3β-hydroxyseroid dehydrogenase, 17β-hydroxyseroid dehydrogenase, plasma levels of testosterone luteinizing hormone, follicle stimulating hormone, prolactin, the numbers of preleptotine spermatocytes, midpachytene spermatocytes and stage 7 spermatids of stage VII seminiferous epithelium cycle in EG when compared with CG. A significant elevation (P < 0.05) in plasma corticosterone and testicular content of malondialdehyde along with a significant reduction (P < 0.05) in glutathione, ascorbic acid, α-tocopherol, superoxide dismutase, catalase and glutathione-peroxidase, and glutathione-S-transferase were noted in testes of EG compared with CG. No significant change was noted in final bodyweight or numbers of spermatogonia-A among the groups. Furthermore, L-ascorbic acid supplementation restored the above parameters to the control level. Conclusion  It can be concluded that intensive swimming exercise induced oxidative stress causes dysfunctions in the male reproductive system, which can be protected by L-ascorbic acid.  相似文献   
42.
Mutations in CTC1 lead to the telomere syndromes Coats Plus and dyskeratosis congenita (DC), but the molecular mechanisms involved remain unknown. CTC1 forms with STN1 and TEN1 a trimeric complex termed CST, which binds ssDNA, promotes telomere DNA synthesis, and inhibits telomerase-mediated telomere elongation. Here we identify CTC1 disease mutations that disrupt CST complex formation, the physical interaction with DNA polymerase α-primase (polα-primase), telomeric ssDNA binding in vitro, accumulation in the nucleus, and/or telomere association in vivo. While having diverse molecular defects, CTC1 mutations commonly lead to the accumulation of internal single-stranded gaps of telomeric DNA, suggesting telomere DNA replication defects as a primary cause of the disease. Strikingly, mutations in CTC1 may also unleash telomerase repression and telomere length control. Hence, the telomere defect initiated by CTC1 mutations is distinct from the telomerase insufficiencies seen in classical forms of telomere syndromes, which cause short telomeres due to reduced maintenance of distal telomeric ends by telomerase. Our analysis provides molecular evidence that CST collaborates with DNA polα-primase to promote faithful telomere DNA replication.  相似文献   
43.
A fuzzy model has been developed for the optimization of high-shear wet granulation wetting on a plant scale depending on the characteristics of pharmaceutical active substance particles. The model optimized on the basis of experimental data involves a set of rules obtained from expert knowledge and full-scale process data. The skewness coefficient of particle size distribution and the tapped density of the granulated mixture were chosen as the model input variables. The output of the fuzzy ruled system is the optimal quantity of wetting liquid. In comparison to manufacturing practice, a very strong sensitivity of the optimal quantity of the added wetting liquid to the size and shape of the active substance particles has been identified by fuzzy modeling.  相似文献   
44.
45.
46.
ObjectiveWe conducted a phenotype-wide association study (PheWAS) to compare diagnoses among Blacks with those of Whites in one health center in Tennessee using data from 1,883,369 patients.MethodsWe used our deidentified EHR, the Synthetic Derivative, to assess risk of diagnoses associated with Black as compared with White race using Firth logistic regression with covariates including age, sex, and density of clinical encounters.ResultsThere were anchoring associations in both directions, including the highest increased risk for Blacks of having sickle cell anemia, and strongest decreased risk of basal cell carcinoma. Results included established areas of disparity and many novel associations.ConclusionsPheWAS is a viable tool for calculating risk associated with any biomarker. The current analysis provide a new approach to generating hypotheses and understanding the breadth of health disparities. Future analyses will further explore causality, risk factors, and potential confounders not accounted for here.  相似文献   
47.
48.
49.
50.
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