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   1339895篇
  免费   95805篇
  国内免费   3194篇
耳鼻咽喉   19754篇
儿科学   40272篇
妇产科学   38696篇
基础医学   187745篇
口腔科学   39860篇
临床医学   113263篇
内科学   263156篇
皮肤病学   30272篇
神经病学   106609篇
特种医学   53817篇
外国民族医学   435篇
外科学   208852篇
综合类   31958篇
现状与发展   6篇
一般理论   436篇
预防医学   92362篇
眼科学   31501篇
药学   100669篇
  5篇
中国医学   3294篇
肿瘤学   75932篇
  2018年   11916篇
  2015年   12111篇
  2014年   16944篇
  2013年   25517篇
  2012年   33373篇
  2011年   35229篇
  2010年   20962篇
  2009年   20417篇
  2008年   33815篇
  2007年   36975篇
  2006年   37523篇
  2005年   36264篇
  2004年   35270篇
  2003年   34248篇
  2002年   33733篇
  2001年   63729篇
  2000年   65443篇
  1999年   55495篇
  1998年   14724篇
  1997年   13529篇
  1996年   12997篇
  1995年   12285篇
  1994年   11514篇
  1992年   42787篇
  1991年   41302篇
  1990年   40580篇
  1989年   39577篇
  1988年   36984篇
  1987年   36424篇
  1986年   34918篇
  1985年   33107篇
  1984年   24828篇
  1983年   21055篇
  1982年   12667篇
  1981年   11572篇
  1980年   10773篇
  1979年   23924篇
  1978年   17069篇
  1977年   14837篇
  1976年   13386篇
  1975年   15267篇
  1974年   18081篇
  1973年   17563篇
  1972年   16811篇
  1971年   15720篇
  1970年   14915篇
  1969年   14349篇
  1968年   13462篇
  1967年   12016篇
  1966年   11258篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
International Journal of Legal Medicine - Sex identification is a primary step in forensic analysis of skeletal remains. The accuracy of sex estimation methods greatly depends on the sexual...  相似文献   
132.
133.
Introduction: Cancer treatment is moving away from conventional cytotoxic drugs and towards agents that target specific proteins and mechanisms important to cancer development or survival. The Hedgehog Pathway (HhP) is a signal transduction pathway and its constitutive activation is tumorigenic in basal cell carcinoma (BCC). The HhP enables phenotypic flexibility, and channels tumor-stroma interactions. As a result, it is over-expressed in numerous cancers as well as in the tumor microenvironment and may represent a promising therapeutic target.

Areas covered: In this article, we review the rationale for targeting HhP and its role as an oncogenic driver, in tumor epithelial-to-mesenchymal transition (EMT), and in the tumor microenvironment and describe the results of preclinical and clinical studies involving HhP inhibitors.

Expert opinion: HhP activation plays an important role in both the tumor microenvironment and tumor EMT which can lead to treatment resistance for a number of different malignancies. In addition to standard use in BCC, several HhP inhibitors are in preclinical, early, and mid-stage clinical development for other solid and hematologic malignancies.  相似文献   
134.
135.
136.
Solid-state reactions between sodium hydride and sodium hydroxide are unusual among hydride-hydroxide systems since hydrogen can be stored reversibly. In order to understand the relationship between hydrogen uptake/release properties and phase/structure evolution, the dehydrogenation and hydrogenation behavior of the Na-O-H system has been investigated in detail both ex- and in-situ. Simultaneous thermogravimetric-differential thermal analysis coupled to mass spectrometry (TG-DTA-MS) experiments of NaH-NaOH composites reveal two principal features: Firstly, an H2 desorption event occurring between 240 and 380 °C and secondly an additional endothermic process at around 170 °C with no associated weight change. In-situ high-resolution synchrotron powder X-ray diffraction showed that NaOH appears to form a solid solution with NaH yielding a new cubic complex hydride phase below 200 °C. The Na-H-OH phase persists up to the maximum temperature of the in-situ diffraction experiment shortly before dehydrogenation occurs. The present work suggests that not only is the inter-phase synergic interaction of protic hydrogen (in NaOH) and hydridic hydrogen (in NaH) important in the dehydrogenation mechanism, but that also an intra-phase Hδ+… Hδ– interaction may be a crucial step in the desorption process.  相似文献   
137.
Vitamin D is responsible for multiple metabolic functions in humans. Rickets are the most common disease caused by vitamin D deficiency. It is caused by poor calcium intake resulting in poor serum-ionized calcium. The purpose of this study is to develop a rapid, sensitive, and feasible method to determine the 25-hydroxy-vitamin D3 (25(OH)D3) levels in blood samples for clinical assessment. In this study, gas chromatography coupled mass spectrometry with trimethylsilyl derivatization (TMS-GC-MS) is the most suitable protocol for quantitative analyses of 25(OH)D3. Performance of method was evaluated and compared with liquid chromatography and immunoassay. Method validation has been carried out with plasma specimens. The limit of quantitation of TMS-GC-MS method is 1.5 ppb with good linear correlation. Furthermore, the dietary intake and nutritional status of vegetarian and non-vegetarians in Taiwan were assessed by our validated method. As a result, this vitamin D nutrition survey demonstrates that most Taiwanese people have insufficient vitamin D. Due to dietary habits; the male vegans may have the highest risk of vitamin D deficiency.  相似文献   
138.
139.
140.
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