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   1337426篇
  免费   100340篇
  国内免费   4288篇
耳鼻咽喉   16811篇
儿科学   43644篇
妇产科学   36438篇
基础医学   198049篇
口腔科学   35965篇
临床医学   129715篇
内科学   258824篇
皮肤病学   26401篇
神经病学   112073篇
特种医学   48217篇
外国民族医学   368篇
外科学   184342篇
综合类   28776篇
现状与发展   1篇
一般理论   460篇
预防医学   114429篇
眼科学   28985篇
药学   98915篇
  6篇
中国医学   3169篇
肿瘤学   76466篇
  2021年   10959篇
  2019年   11680篇
  2018年   16368篇
  2017年   12316篇
  2016年   13292篇
  2015年   15260篇
  2014年   20868篇
  2013年   32152篇
  2012年   44374篇
  2011年   47025篇
  2010年   27156篇
  2009年   24990篇
  2008年   42842篇
  2007年   45187篇
  2006年   45280篇
  2005年   43712篇
  2004年   41669篇
  2003年   39592篇
  2002年   38381篇
  2001年   60886篇
  2000年   62569篇
  1999年   52333篇
  1998年   14600篇
  1997年   13286篇
  1996年   13134篇
  1995年   12466篇
  1994年   11642篇
  1993年   10932篇
  1992年   41602篇
  1991年   40787篇
  1990年   39474篇
  1989年   37385篇
  1988年   34612篇
  1987年   33713篇
  1986年   32170篇
  1985年   30661篇
  1984年   23046篇
  1983年   19606篇
  1982年   11766篇
  1979年   20820篇
  1978年   14825篇
  1977年   12076篇
  1976年   11880篇
  1975年   12116篇
  1974年   14808篇
  1973年   14476篇
  1972年   13369篇
  1971年   12419篇
  1970年   11486篇
  1969年   10412篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
961.
The proliferative T-lymphocyte response to streptokinase   总被引:1,自引:0,他引:1  
Purified streptokinase was found to initiate a proliferative T-lymphocyte response. The response was characterized by dose-response and kinetics investigations. Streptokinase did not initiate any response when tested on T lymphocytes from newborns, thus indicating that the proliferative T-lymphocyte response to streptokinase in vitro is an antigen stimulated activation of T lymphocytes from individuals previously sensitized in vivo. Of healthy individuals, 40% (16 out of 40 tested) showed a significant proliferative response to streptokinase. Methylprednisolone, cyclosporin A, theophyllamine and verapamil all inhibited the streptokinase-stimulated proliferative T-lymphocyte responses in a dose-dependent manner.  相似文献   
962.
We present a modified EEG montage that detects small interchannel time differences and assists in localizing the epileptogenic focus. Regions with apparently synchronous epileptic discharges are displayed simultaneously in referential and subtraction derivations. The subtraction derivation is a bipolar configuration of two regions of interest that are not necessarily adjacent. The referential derivation reveals the polarity, voltage, and morphology of the two discharges, and the subtraction derivation detects asynchrony; the combined reference-subtraction derivation thus indicates the region that is activated first.  相似文献   
963.
Compared with results obtained in locally anesthetized, paralyzed rats, the dissociative anesthetic ketamine did not alter either the number of spontaneously active striatal neurons or the basal firing rate of striatal neurons; 90% of these cells exhibited the type I striatal neuron waveform. Chloral hydrate anesthesia suppressed both the occurrence and the firing rate of spontaneously active type I cells, but did not alter the activity of type II striatal neurons. Cortical stimulation preferentially activated type II cells in paralyzed rats and in chloral hydrate-anesthetized rats. Thus, under dissociative anesthesia it is possible to study spontaneously active type I striatal neurons. However, a method of activation such as cortical stimulation is necessary to study type II striatal neurons.  相似文献   
964.
Stuttering and tetanic syndrome   总被引:1,自引:0,他引:1  
  相似文献   
965.
Several neurodegenerative diseases, including motor neuron disease (MND), are characterized by formation of abnormal cytoskeleton-derived inclusions which contain ubiquitin (Ubq). We have studied the distribution of Ubq in 26 cases of MND with light and electron microscopic immunocytochemistry. Ubiquitin-positive inclusions were found in neurons of anterior horns in most cases of amyotrophic lateral sclerosis (ALS) but were not present in other forms of MND. Ubiquitin immunoreactivity was observed in 10-15 nm intraneuronal filaments, which were not stained by antibodies to neurofilaments, and on dense bodies of dystrophic neurites throughout the neuropil of anterior horns and pyramidal tracts. Data analysis showed a trend toward lower percentage of Ubq-positive neurons in cases with longer duration of illness or lower number of neurons. A high percentage of Ubq-positive inclusions occurred in cases with an aggressive clinical course, suggesting that ubiquitination takes place at early stages of the disease.  相似文献   
966.
967.
Although many monoclonal antibodies have been made in human colon cancer, none of them are from the Chinese species. Recently, a colon cancer cell line CC-M2 established from a Chinese patient has been completely characterized and used as immunogen to produce monoclonal antibodies. Monoclonal antibodies were produced by standard hybridoma technique. The fusion rate was 95.8%. An isotype IgG1 of high proliferation named as Sam-2 was used in this study. The titers were measured around 10(4). Further studies on MoAb Sam-2 through indirect immunofluorescent and immunoperoxidase tests revealed its good specificity and sensitivity in colorectal cancer tissue. In CEA study, the result indicated that Sam-2 may react on a non-CEA related antigen. For further clinical application, the antigen was identified as a glycoprotein by chemical resistant test. In preliminary studies using sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting techniques, Sam-2 could recognize two closed antigens or a dimer antigen with molecular weight 25.2 and 27 Kd respectively.  相似文献   
968.
969.
Approximately one quarter of a series of 45 schizophrenic and schizoaffective patients with operationally diagnosed episodes of postpsychotic depression were also found to have anxiety symptoms consistent with the panic-attack syndrome. The incidence of such attacks was distributed across all demographic groups. Heuristic and treatment implications of this observation are considered.  相似文献   
970.
Carnitine, valproate, and toxicity   总被引:1,自引:0,他引:1  
Carnitine is an important nutrient that is present in the diet (particularly in meat and dairy products) and is synthesized from dietary amino acids. It functions to assist long-chain fatty acid metabolism and to regulate the ratio of free coenzyme A to acylcoenzyme A in the mitochondrion. Carnitine deficiency occurs in primary inborn errors of metabolism, in nutritional deficiency, and in various other disorders including antiepileptic drug therapy. Valproate therapy is often associated with decreased carnitine levels and occasionally with true carnitine deficiency. Some experimental and clinical evidence links valproate-induced carnitine deficiency with hepatotoxicity, but this evidence is limited and inconclusive. Carnitine supplementation has been useful in some studies, but these data are also limited. Young children with neurologic disabilities taking multiple antiepileptic drugs may have the greatest risk for carnitine deficiency. Measurement of carnitine levels appears warranted in these patients and in patients with symptoms and signs of possible carnitine deficiency.  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