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   3205篇
  免费   238篇
  国内免费   12篇
耳鼻咽喉   22篇
儿科学   106篇
妇产科学   125篇
基础医学   458篇
口腔科学   94篇
临床医学   422篇
内科学   647篇
皮肤病学   119篇
神经病学   176篇
特种医学   62篇
外科学   240篇
综合类   55篇
一般理论   4篇
预防医学   254篇
眼科学   93篇
药学   293篇
中国医学   58篇
肿瘤学   227篇
  2024年   8篇
  2023年   59篇
  2022年   180篇
  2021年   244篇
  2020年   182篇
  2019年   230篇
  2018年   226篇
  2017年   127篇
  2016年   152篇
  2015年   125篇
  2014年   172篇
  2013年   216篇
  2012年   275篇
  2011年   258篇
  2010年   128篇
  2009年   93篇
  2008年   136篇
  2007年   115篇
  2006年   104篇
  2005年   101篇
  2004年   74篇
  2003年   51篇
  2002年   47篇
  2001年   14篇
  2000年   10篇
  1999年   13篇
  1998年   7篇
  1997年   7篇
  1996年   2篇
  1995年   5篇
  1994年   6篇
  1993年   6篇
  1992年   7篇
  1991年   13篇
  1990年   5篇
  1989年   4篇
  1988年   8篇
  1987年   12篇
  1986年   6篇
  1985年   10篇
  1984年   2篇
  1983年   3篇
  1980年   2篇
  1979年   4篇
  1978年   1篇
  1977年   1篇
  1976年   1篇
  1973年   2篇
  1936年   1篇
排序方式: 共有3455条查询结果,搜索用时 15 毫秒
61.
Developments in the fields of lab-on-a-chip and microfluidic technology have benefited nanomaterial production processes due to fluid miniaturization. The ability to acquire, manage, create, and modify structures on a nanoscale is of great interest in scientific and technological fields. Recently, more attention has been paid to the production of core–shell nanomaterials because of their use in various fields, such as drug delivery. Heterostructured nanomaterials have more reliable performance than the individual core or shell materials. Nanoparticle synthesis is a complex process; therefore, various techniques exist for the production of different types of nanoparticles. Among these techniques, microfluidic methods are unique and reliable routes, which can be used to produce nanoparticles for drug delivery applications.

Developments in the fields of lab-on-a-chip and microfluidic technology have benefited nanomaterial production processes due to fluid miniaturization.  相似文献   
62.
63.
64.
Although poly (ionic liquids) (PILs) have attracted great research interest owing to their various applications, the performance of nanoporous PILs has been rarely developed in the catalysis field. To this end, a micro–mesoporous PIL with acid–base bifunctional active sites was designed and fabricated by two different polymerization protocols including hydrothermal and classical precipitation polymerization in this paper. Based on our observations, hydrothermal conditions (high temperature and pressure) enabled the proposed sonocatalyst to possess a great porous structure with a high specific surface area (SBET: 315 m2 g−1) and thermal stability (around 450 °C for 45% weight loss) through strengthening cross-linking. In a comparative study, the preferred nanoporous PIL was selected and utilized as the sonocatalyst in a multicomponent reaction of isatins, primary amines, and thioglycolic acid. In the following, a variety of new and known pharmaceutical spiro-4-thiazolidinone derivatives were synthesized at room temperature and obtained excellent yields (>90%) within short reaction times (4–12 min) owing to the substantial synergistic effect between ultrasound irradiation and magnetically separable catalyst.

Sustainable synthesize of a new mesoporous poly (ionic liquid) as acid–base bifunctional catalyst for environmental being preparation of monospiro derivatives has been developed.  相似文献   
65.
Galactosyl transferase knock-out pig lungs fail rapidly in baboons. Based on previously identified lung xenograft injury mechanisms, additional expression of human complement and coagulation pathway regulatory proteins, anti-inflammatory enzymes and self-recognition receptors, and knock-down of the β4Gal xenoantigen were tested in various combinations. Transient life-supporting GalTKO.hCD46 lung function was consistently observed in association with either hEPCR (n = 15), hTBM (n = 4), or hEPCR.hTFPI (n = 11), but the loss of vascular barrier function in the xenograft and systemic inflammation in the recipient typically occurred within 24 h. Co-expression of hEPCR and hTBM (n = 11) and additionally blocking multiple pro-inflammatory innate and adaptive immune mechanisms was more consistently associated with survival >1 day, with one recipient surviving for 31 days. Combining targeted genetic modifications to the lung xenograft with selective innate and adaptive immune suppression enables prolonged initial life-supporting lung function and extends lung xenograft recipient survival, and illustrates residual barriers and candidate treatment strategies that may enable the clinical application of other organ xenografts.  相似文献   
66.
Although existence of ovarian stem cells (OSCs) in mammalian postnatal ovary is still under controversy, however, it has been almost accepted that OSCs are contributing actively to folliculogenesis and neo-oogenesis. Recently, various methods with different efficacies have been employed for OSCs isolation from ovarian tissue, which these methods could be chosen depends on aim of isolation and accessible equipments and materials in lab. Although isolated OSCs from different methods have various traits and characterizations, which might become from their different nature and origin, however these stem cells are promising source for woman infertility treatment or source of energy for women with a history of repeat IVF failure in near future. This review has brought together and summarized currently used protocols for isolation and propagation of OSCs in vitro.  相似文献   
67.
Leukocyte adhesion deficiency type I (LAD I) is a rare, inherited, autosomal recessive, immunodeficiency disease caused by the combined loss of expression on the surface of leukocytes of the leukocyte integrins. We describe the clinical and laboratory findings for 15 patients with LAD I. The range of patients’ ages was from 10 month to 14 years (median 4 years) and 93.3% of their parents had consanguineous marriages. The most commonly occurred manifestations were: recurrent infections (93.3%), poor wound healing (86%), oral ulcers (86%), and skin abscesses (80%). The most specific laboratory findings were defect in CD18 in all of 15 patients. The most common symptoms in these patients are poor wound healing and oral ulcer, so, the clinical physicians should pay special attention to these symptoms. Furthermore, because of considerable rate of consanguineous marriages in parents of LAD patients, we suggested more genetic studies on this disease and genetic consultation for these families. An erratum to this article can be found at  相似文献   
68.
Lasers in Medical Science - The combination of multiple therapeutic and diagnostic functions is fast becoming a key feature in the area of clinical oncology. The advent of nanotechnology promises...  相似文献   
69.
Purpose: One of the consequences of trauma-related injuries is disability. There are more than one billion people with disabilities worldwide. Disability in people reduces their quality of life. The goal of this study was to determine the rate of post-trauma stress and disability related to trauma in the population over 15 years old in Kashan during a solar year of 2018-2019. Methods: This is a cross-sectional population-based study. A cluster sampling method was used in the city of Kashan, and 3880 persons were interviewed with individuals randomly selected in each household. If a person had trauma during one year ago, the World Health Organization Disability Assessment Schedule 2.0 and Post Trauma Stress Disorder (PTSD) Checklist were applied for further interview. Data were analyzed using Chi-square test or t-test. Results: Among the 3880 participants residing in Kashan, 274 (7.1%) reported a history of traumatic injury during one year ago in 2018-2019. Incidence of all injuries was estimated to be 70.61 (62.60-78.70) per 1000 people. For the trauma population, 213 (77.7%) were male and 75.1% were married. About half of them (50.3%, 138/274) aged 21e39 years. The most common cause of injuries was related to traffic accidents: 140 (51.1%). Of the 274 trauma participants, 47 (17.2%) reported PTSD; 244 (89.1%) had a mild disability, and 30 (10.9%) reported moderate disability. Conclusion: One of the main causes of disability in the human community is the traumatic injuries. According to the results of this study, 89.1% of trauma participants have sustained at last mild disability following trauma. These people require follow-up and post-treatment support. It should be noted that psychological complications such as PTSD are as significant as physical symptoms.  相似文献   
70.
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