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   6177篇
  免费   469篇
  国内免费   18篇
耳鼻咽喉   70篇
儿科学   153篇
妇产科学   147篇
基础医学   968篇
口腔科学   94篇
临床医学   595篇
内科学   1389篇
皮肤病学   142篇
神经病学   369篇
特种医学   318篇
外国民族医学   1篇
外科学   1145篇
综合类   41篇
一般理论   3篇
预防医学   240篇
眼科学   155篇
药学   397篇
中国医学   9篇
肿瘤学   428篇
  2022年   38篇
  2021年   72篇
  2020年   53篇
  2019年   69篇
  2018年   94篇
  2017年   88篇
  2016年   111篇
  2015年   149篇
  2014年   166篇
  2013年   201篇
  2012年   304篇
  2011年   329篇
  2010年   169篇
  2009年   188篇
  2008年   303篇
  2007年   321篇
  2006年   298篇
  2005年   301篇
  2004年   248篇
  2003年   254篇
  2002年   227篇
  2001年   182篇
  2000年   214篇
  1999年   200篇
  1998年   84篇
  1997年   81篇
  1996年   61篇
  1995年   60篇
  1994年   54篇
  1993年   51篇
  1992年   108篇
  1991年   109篇
  1990年   106篇
  1989年   123篇
  1988年   69篇
  1987年   72篇
  1986年   77篇
  1985年   61篇
  1984年   52篇
  1983年   42篇
  1982年   38篇
  1981年   34篇
  1980年   32篇
  1979年   77篇
  1978年   39篇
  1976年   34篇
  1974年   52篇
  1973年   40篇
  1972年   47篇
  1971年   49篇
排序方式: 共有6664条查询结果,搜索用时 15 毫秒
41.
42.
The objective of this study was to evaluate the sensitivity of posturographic parameters (PP) to changes in acquisition settings. A group of eight young adults underwent a set of typical orthostatic posture trials, and selected PP were then calculated from a set of centre of pressure (CoP) displacement time series obtained by applying different cut-off frequencies to the same set of raw data. Four PP out of 11 showed significant changes with respect to cut-off frequency. Statistical mechanics parameters exhibited smaller sensitivity than summary measures. On the basis of the results obtained, a proposal for a standard cut-off frequency and a sampling rate value is embodied in the paper together with some suggestions on measurement settings, with a view to standardized use of instrumentation for quantitative analysis in orthostatic posturography.  相似文献   
43.
BACKGROUND: Germins and the related germin-like proteins (GLPs) are glycoproteins expressed in many plants in response to biotic and abiotic stress. To test the potential impact of germins and GLPs, recombinant germin from Triticum aestivum (tGermin) and GLPs from Arabidopsis thaliana (tGLP), both produced in transformed tobacco plants, were used. METHODS: Sera from 82 patients with type I allergy to birch, grass or mugwort pollen and/or wheat were tested in immunoblot for IgE binding to tGermin and tGLP, and the IgE reactivity after chemical and enzymatic deglycosylation was analysed. The biological activity of tGermin and tGLP was determined in a histamine release assay and in skin prick testing (SPT). RESULTS: In an immunoblotting assay, 24 out of 82 tested sera (29.26%) from allergic patients showed IgE-binding to tGermin, and 18 of these sera (21.95%) displayed also IgE-binding to tGLP. The deglycosylation experiments indicated that glycan moieties contribute significantly to the IgE-binding of tGermin and tGLP. Both tGermins and tGLP induced specifically histamine release in an in vitro assay as well as in SPT. CONCLUSION: Our in vitro and in vivo findings demonstrate that germin and GLPs are capable to bind IgE most likely via carbohydrate determinants, and represent allergenic molecules.  相似文献   
44.
45.
46.
Zusammenfassung 1. Es werden an quergestreiften Muskeln (Zwerchfell, Herzvorhof von Warmblütern, Froschherz) unter den Bedingungen von Substratund Sauerstoffmangel Funktion und histologischer Zustand verglichen.2. Drosselung der Energiezufuhr führt in jedem Falle zu negativer Inotropie und diastolischem Stillstand. Dies führt zu dem zwingenden Schluß, daß die Kontraktion und nicht die Erschlaffung den energieverbrauchenden Teil des Kontraktionsvorganges darstellt.3. Gleichzeitiger Glucose- und Sauerstoffmangel führt erst mit dem Erlöschen der Glykogenolyse zur Kontraktur, die nach völligem Glykogenschwund irreversibel wird (Totenstarre).4. Die Totenstarre wird als Modellkontraktion abgelehnt.5. Aus den untersuchten Mangelbedingungen läßt sich eine Reihenfolge der Energieausnützung für den quergestreiften Muskel ableiten, wobei wesentliche Unterschiede zwischen Warmblüter und Kaltblüter bestehen.Mit 7 Textabbildungen  相似文献   
47.
48.
Aims—To investigate the correlation between the expression of the p53 and mdm-2 oncoproteins and to assess their prognostic value in colorectal cancer.  相似文献   
49.
E Schiaffino  C Schmid  G Mortara 《Pathologica》1990,82(1082):687-693
Morphology of pancreas (either esocrine, either endocrine) was studied in 29 cases of surgically treated chronic pancreatitis (27 cases of chronic calcifying pancreatitis and 2 cases of chronic obstructive pancreatitis). Parenchymal sclerosis in chronic calcifying pancreatitis (CCP) which represents the goal of our study was graded as mild (10 cases), moderate (10) and severe (7). Immunoperoxidase staining (PAP method) for insulin, glucagon, somatostatin, pancreatic polipeptide (PP), vasoactive intestinal polipeptide (VIP) and gastrin, was used to investigate endocrine pancreas. Acinar sclerosis and endocrine damage were closely related. Progression of sclerosis into islet appears to follow vascular pedicles producing a fragmentation into small cell groups as final result. In all cases of moderate or severe sclerosis, A/B cell ratio was increased due to the reduction of insulin positive cells. "Adenoma-like complexes", i.e., apparent concentration of islets, resulting from the loss of the acinar component, were observed in 7 cases with moderate or severe sclerosis. Nesidioblastosis was a prominent feature in all cases but one, with a positivity for insulin in 11 cases, for glucagon in 13, for somatostatin in 6 and for PP in 17. No positivity for gastrin was observed, while VIP was detected in a few ganglia. An increased amount of PP cells in islet and budding from the ducts was noticed and their presence outside the pancreatic head was demonstrable in 4 out of the 7 distal pancreatectomy specimens. Our data confirm the secondary involvement of the endocrine pancreas in the sclerotic acinar process.  相似文献   
50.
Effects of interpolating additional reinforcement into an existing "natural" schedule of reinforcement were examined on subsequent responding when experimenter-controlled reinforcement was withdrawn. Six mildly to moderately mentally retarded children were given from 10 to 45 minutes of interpolated reinforcement for target behavior that interfered with habilitation. When the interpolated reinforcement was discontinued, the forms of responding returned to those of initial baseline, and the rates were lower. The significantly lower rate of responding in the return-to-baseline condition suggests that such a procedure may be effectively incorporated into behavior-reduction programs.  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