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   6383篇
  免费   448篇
  国内免费   23篇
耳鼻咽喉   66篇
儿科学   338篇
妇产科学   146篇
基础医学   756篇
口腔科学   122篇
临床医学   590篇
内科学   1678篇
皮肤病学   79篇
神经病学   344篇
特种医学   180篇
外国民族医学   1篇
外科学   794篇
综合类   136篇
一般理论   4篇
预防医学   397篇
眼科学   286篇
药学   404篇
中国医学   45篇
肿瘤学   488篇
  2023年   63篇
  2022年   165篇
  2021年   256篇
  2020年   132篇
  2019年   173篇
  2018年   217篇
  2017年   148篇
  2016年   160篇
  2015年   168篇
  2014年   262篇
  2013年   296篇
  2012年   469篇
  2011年   461篇
  2010年   226篇
  2009年   202篇
  2008年   327篇
  2007年   338篇
  2006年   288篇
  2005年   261篇
  2004年   283篇
  2003年   240篇
  2002年   237篇
  2001年   115篇
  2000年   134篇
  1999年   115篇
  1998年   55篇
  1997年   48篇
  1996年   37篇
  1995年   24篇
  1994年   22篇
  1993年   17篇
  1992年   98篇
  1991年   57篇
  1990年   69篇
  1989年   62篇
  1988年   78篇
  1987年   59篇
  1986年   55篇
  1985年   62篇
  1984年   37篇
  1983年   23篇
  1982年   17篇
  1981年   20篇
  1979年   49篇
  1978年   18篇
  1976年   16篇
  1974年   16篇
  1973年   17篇
  1972年   19篇
  1969年   21篇
排序方式: 共有6854条查询结果,搜索用时 15 毫秒
101.
Malik NN 《Lancet》2004,364(9432):411-412
  相似文献   
102.
Erosion of a retained surgical sponge into the intestine is an unusual occurrence and may make its appearance months or years later. The demonstration of a distended bowel by the barium-impregnated mass with multiple polypoidal filling defects in a patient who has undergone previous laparotomy should lead the physician to suspect a retained surgical sponge. Surgical intervention is rewarding.  相似文献   
103.
Prenylated flavonoids represent a unique class of naturally occurring compounds and have proved to be an important source of chemically diverse novel metabolites. Nevertheless, they possess wild array of biological activities. 4′-Methoxy licoflavanone is a prenylated flavonoid isolated from stem bark of Erytherina subrossa. Herein, we report the synthesis of O-alkyl analogs (2a2m) and 1,2,3 triazole conjugate (314) of 4′-methoxy licoflavanone by selective modification at C-7 position in the chromane nucleus. In addition, all the derivatives were evaluated for in vitro antiproliferative activity against a panel of cancer cell lines including pancreatic cancer (Mia PaCa-2), prostate cancer (PC-3), and human leukemia (HL-60) cells. The results revealed that some analogs including 2e and 2m exhibited better cytotoxicity effect than parent compound, specifically on Mia PaCa-2 cell lines.  相似文献   
104.
The defects in the host lattice play a major role in tuning the surface roughness, optical band gap and the room temperature ferromagnetism (RTFM) of ZnO thin films. Herein, we report a novel approach to tailor the band gap and RTFM of a ZnO nanostructure by varying the angle of implantation of 60 keV N ions keeping the ion fluence of 1 × 1016 ions per cm2 and the beam size of 3 mm constant. The implantation was performed by changing the thin films'' orientations at 30°, 60° and 90° with respect to the incident beams. Remarkably, an enhancement of ∼6 times in RTFM, tuning in band gap from 3.27 to 3.21 eV and ∼60% reduction in surface roughness were noticed when the ion implantation was done at 60° to the normal. This novel technique may be suitable for tuning the physical properties of nanostructures for their application in the spintronics, semiconductor and solar cell industries.

The defects in the host lattice play a major role in tuning the surface roughness, optical band gap and the room temperature ferromagnetism of ZnO thin films.  相似文献   
105.
106.
107.

Objectives

To identify clinically actionable genetic variants from targeted sequencing of 68 disease-related genes, estimate their penetrance, and assess the impact of disclosing results to participants and providers.

Patients and Methods

The Return of Actionable Variants Empirical (RAVE) Study investigates outcomes following the return of pathogenic/likely pathogenic (P/LP) variants in 68 disease-related genes. The study was initiated in December 2016 and is ongoing. Targeted sequencing was performed in 2533 individuals with hyperlipidemia or colon polyps. The electronic health records (EHRs) of participants carrying P/LP variants in 36 cardiovascular disease (CVD) genes were manually reviewed to ascertain the presence of relevant traits. Clinical outcomes, health care utilization, family communication, and ethical and psychosocial implications of disclosure of genomic results are being assessed by surveys, telephone interviews, and EHR review.

Results

Of 29,208 variants in the 68 genes, 1915 were rare (frequency <1%) and putatively functional, and 102 of these (60 in 36 CVD genes) were labeled P/LP based on the American College of Medical Genetics and Genomics framework. Manual review of the EHRs of participants (n=73 with P/LP variants in CVD genes) revealed that 33 had the expected trait(s); however, only 6 of 45 participants with non–familial hypercholesterolemia (FH) P/LP variants had the expected traits.

Conclusion

Expected traits were present in 13% of participants with P/LP variants in non-FH CVD genes, suggesting low penetrance; this estimate may change with additional testing performed as part of the clinical evaluation. Ongoing analyses of the RAVE Study will inform best practices for genomic medicine.  相似文献   
108.
Proceedings of the National Academy of Sciences, India Section B: Biological Sciences - Mutations in human flavin monooxygenase-3 (hFMO3) enzyme have been implicated in the rare autosomal recessive...  相似文献   
109.
Objectives: This study aimed to examine “intention to” and “performance of” oral hygiene care to stroke patients using the Theory of Planned Behavior.

Materials and methods: A large scale survey of 13 centers in Malaysia was conducted involving 806 nurses in relation to oral hygiene care intentions and practices. In addition, information on personal and environmental factors was collected.

Results: The response rate was 95.6% (778/806). The domains of the Theory of Planned Behavior were significantly associated with general intention to perform oral hygiene care: attitudes (β?=?0.21, p?p?p?p?<0.01), controlling for other factors. Knowledge scores, training, access to oral hygiene guidelines and kits, as well as working ward type were identified as key factors associated with intention and practice of oral hygiene care.

Conclusion: The Theory of Planned Behavior provides understanding of “intention to” and “performance of” oral hygiene care to stroke patients. Several provider and environmental factors were also associated with intentions and practices. This has implications for understanding and improving the implementation of oral hygiene care in stroke rehabilitation.

  • Implications for Rehabilitation
  • Oral hygiene care is crucial for stroke patients as it can prevent oral health problems and potentially life threatening events (such as aspiration pneumonia).

  • Despite oral hygiene care being relative simple to perform, it is often neglected during stroke rehabilitation.

  • A large-scale national survey was conducted to understand “intentions to” and “performance of” oral hygiene care to stroke patients using the Theory of Planned Behavior social cognition model.

  • These study findings may have implications and use in promoting oral hygiene care to stroke patients:i) by understanding the pathways and influences to perform oral hygiene care.ii) to conduct health promotion and health education based on behavioral models such as Theory of Planned Behavior.

  相似文献   
110.
AIM:To quantify corneal ultrastructure using laser scanning in vivo confocal microscopy (IVCM) in patients with keratoconus and control subjects.METHODS: Unscarred corneas of 78 keratoconic subjects without a history of contact lens use and 36 age-matched control subjects were evaluated with slit-lamp examination (SLE), corneal topography and laser scanning IVCM. One eye was randomly chosen for analysis. Anterior and posterior stromal keratocyte, endothelial cell and basal epithelial cell densities and sub-basal nerve structure were evaluated.RESULTS: IVCM qualitatively demonstrated enlarged basal epithelial cells, structural changes in sub-basal and stromal nerve fibers, abnormal stromal keratocytes and keratocyte nuclei, and pleomorphism and enlargement of endothelial cells. Compared with control subjects, significant reductions in basal epithelial cell density (5817±306 cells/mm2 vs 4802±508 cells/mm2, P<0.001), anterior stromal keratocyte density (800±111 cells/mm2 vs 555±115 cells/mm2, P<0.001), posterior stromal keratocyte density (333±34 cells/mm2 vs 270±47 cells/mm2, P<0.001), endothelial cell density (2875±223 cells/mm2 vs 2686±265 cells/mm2, P<0.001), sub-basal nerve fiber density (31.2±8.4 nerves/mm2 vs 18.1±9.2 nerves/mm2, P<0.001), sub-basal nerve fiber length (21.4±3.4 mm/mm2 vs 16.1±5.1 mm/mm2, P<0.001), and sub-basal nerve branch density (median 50.0 (first quartile 31.2 - third quartile 68.7) nerve branches/mm2 vs median 25.0 (first quartile 6.2 - third quartile 45.3) nerve branches/mm2, P<0.001) were observed in patients with keratoconus.CONCLUSION: Significant microstructural abnormalities were identified in all corneal layers in the eyes of subjects with keratoconus using IVCM. This non-invasive in vivo technique provides an important means to define and follow progress of microstructural changes in patients with keratoconus.  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