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   1753篇
  免费   151篇
  国内免费   11篇
耳鼻咽喉   4篇
儿科学   48篇
妇产科学   67篇
基础医学   194篇
口腔科学   45篇
临床医学   174篇
内科学   371篇
皮肤病学   22篇
神经病学   118篇
特种医学   130篇
外科学   252篇
综合类   23篇
一般理论   2篇
预防医学   169篇
眼科学   17篇
药学   148篇
肿瘤学   131篇
  2021年   30篇
  2019年   23篇
  2018年   28篇
  2017年   18篇
  2016年   27篇
  2015年   36篇
  2014年   31篇
  2013年   57篇
  2012年   69篇
  2011年   83篇
  2010年   53篇
  2009年   52篇
  2008年   73篇
  2007年   72篇
  2006年   61篇
  2005年   56篇
  2004年   42篇
  2003年   68篇
  2002年   53篇
  2001年   60篇
  2000年   46篇
  1999年   49篇
  1998年   40篇
  1997年   48篇
  1996年   47篇
  1995年   42篇
  1994年   28篇
  1993年   34篇
  1992年   38篇
  1991年   33篇
  1990年   35篇
  1989年   32篇
  1988年   39篇
  1987年   33篇
  1986年   43篇
  1985年   35篇
  1984年   21篇
  1983年   25篇
  1982年   25篇
  1981年   20篇
  1980年   14篇
  1979年   14篇
  1978年   11篇
  1977年   11篇
  1976年   16篇
  1975年   12篇
  1973年   11篇
  1972年   10篇
  1971年   13篇
  1967年   10篇
排序方式: 共有1915条查询结果,搜索用时 15 毫秒
91.
Eight patients with Fanconi's anemia were given cyclophosphamide alone (seven patients) or combined with procarbazine and antithymocyte globulin (one patient) followed by marrow grafts from HLA-identical siblings. All patients had engraftment. Seven developed acute and three chronic graft-versus-host disease (GVHD). Three patients died with GVHD and infectious complications (days 19, 56, and 82) and one with an intracerebral hemorrhage (day 540). Four patients are surviving 647- 3435 days after grafting, two are well, and two have chronic GVHD that is improving. These results show that Fanconi's anemia can be treated successfully by allogeneic marrow transplantation.  相似文献   
92.
Sexually dimorphic regions are described in two areas of the guinea pig brain: the medial preoptic area (MPOA) and the bed nucleus of the stria terminalis (BNST). The volume of a darkly staining portion of the MPOA is approximately 4-fold larger in male than in female guinea pigs, and the volume of a darkly staining portion of the BNST is approximately 36% larger in male than in female animals. The sex differences in both of these areas are present in animals that have been gonadectomized as adults as well as in intact animals, suggesting that they result from differences between the sexes in the hormonal environment during early development. Both the MPOA and the BNST bind high levels of gonadal steroids early in life, during the period when functional differentiation occurs. It is possible that dramatic morphological sex differences characterize such steroid-binding areas. Furthermore, these sexually dimorphic areas may form an anatomically and functionally interrelated system. Attention to these possibilities may help elucidate more precisely the neural basis for sexually dimorphic functions, as well as the basic mechanisms underlying sexual differentiation of behavior and the brain.  相似文献   
93.
94.
The purpose of this study was to compare and contrast two enzyme immunoassay systems: the enzyme-linked immunosorbent assay (ELISA), which utilizes polystyrene microtiter plates as the adsorptive surface and the enzyme-linked immunoflow assay (ELIFA), which utilizes nitrocellulose membranes. The principal parameter under scrutiny was the denaturing or unfolding effects caused by the interaction of the protein with the adsorptive surfaces in each assay system. These effects were monitored by utilizing two conformationally distinct forms of human C-reactive protein (CRP), the native form of CRP and a denatured form (M-CRP), with a corresponding panel of monoclonal antibodies (MAbs) specific to either CRP or M-CRP. The results show that the ELIFA system was less sensitive than the ELISA system but that the ELIFA assay can be completed in less time than the ELISA. Also, adsorption of native CRP to the polystyrene surface in the ELISA system resulted in conformational changes of the adsorbed native CRP protein such that M-CRP reactive determinants were available for binding with anti-M-CRP MAbs, whereas native CRP adsorbed to the nitrocellulose membrane in the ELIFA system resulted in very limited conversion of CRP to M-CRP reactive epitopes. These results have important implications for development of immunoassays and screening of MAbs for proteins whose conformations may be affected by adsorption to various surfaces.  相似文献   
95.
96.
Behcet’s disease is a rare autoimmune vasculitis characterized by oral aphthosis, genital ulcers, and ocular and cutaneous lesions. Vascular involvement usually affects the veins more commonly than the arteries, and coronary arterial involvement is extremely rare. We report an adolescent with Behcet’s disease who developed a large pseudoaneurysm of the left anterior descending coronary artery requiring a coronary arterial bypass graft.  相似文献   
97.
Background: Enteral nutrition (EN) supports many older and disabled Americans. This study describes the frequency and cost of acute care hospitalization with dehydration and/or malnutrition of Medicare beneficiaries receiving EN, focusing on those receiving home EN. Methods: Medicare 5% Standard Analytic Files were used to determine Medicare spending for EN supplies and the proportion and cost of beneficiaries receiving EN, specifically home EN, admitted to the hospital with dehydration and/or malnutrition. Results: In 2013, Medicare paid $370,549,760 to provide EN supplies for 125,440 beneficiaries, 55% of whom were also eligible for Medicaid. Acute care hospitalization with dehydration and/or malnutrition occurred in 43,180 beneficiaries receiving EN. The most common principal diagnoses were septicemia (21%), aspiration pneumonitis (9%), and pneumonia (5%). In beneficiaries receiving EN at home, >one‐third (37%) were admitted with dehydration and/or malnutrition during a mean observation interval of 231 ± 187 days. Admitted patients were usually hospitalized more than once with dehydration and/or malnutrition (1.73 ± 1.30 admissions) costing $23,579 ± 24,966 per admitted patient, totaling >$129,685,622 during a mean observation interval of 276 ± 187 days. Mortality in the year following enterostomy tube placement was significantly higher for admitted compared with nonadmitted patients (40% vs 33%; P = .05). Conclusion: Acute care hospitalizations with dehydration and/or malnutrition in Medicare beneficiaries receiving EN were common and expensive. Additional strategies to reduce these, with particular focus on vulnerable populations such as Medicaid‐eligible patients, are needed.  相似文献   
98.
Bisphenol A is a commercially important chemical used to make polycarbonate plastic, epoxy resins, and other specialty products. Despite an extensive body of in vitro, animal and human observational studies on the effects of exposure to bisphenol A, no authoritative bodies in the U.S. have adopted or recommended occupational exposure limits for bisphenol A. In 2017, the National Institute for Occupational Safety and Health published a Draft process for assigning health-protective occupational exposure bands, i.e., an airborne concentration range, to chemicals lacking an occupational exposure limit. Occupational exposure banding is a systematic process that uses both quantitative and qualitative toxicity information on selected health effect endpoints to assign an occupational exposure band for a chemical. The Draft process proposes three methodological tiers of increasing complexity for assigning an occupational exposure band. We applied Tier 1 (based on the Globally Harmonized System of Classification and Labelling) and Tier 2 (based on authoritative sources/reviews) to assign an occupational exposure band to bisphenol A. Under both Tier 1 and 2, the occupational exposure band for bisphenol A was “E” (<0.01?mg/m3), an assignment based on eye damage. “E” is the lowest exposure concentration range, reserved for chemicals with high potential toxicity. If eye damage was excluded in assigning an air concentration exposure range, then bisphenol A would band as “D” (>0.01 to 0.1?mg/m3) under Tier 1 (based on reproductive toxicity and respiratory/skin sensitization) and under Tier 2 (based on specific target organ toxicity-repeated exposure). In summary, Tiers 1 and 2 gave the same occupational exposure band for bisphenol A when eye damage was included (“E”) or excluded (“D”) as an endpoint.  相似文献   
99.
100.
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