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   56704篇
  免费   3329篇
  国内免费   745篇
耳鼻咽喉   982篇
儿科学   686篇
妇产科学   830篇
基础医学   9768篇
口腔科学   1367篇
临床医学   5024篇
内科学   10733篇
皮肤病学   1887篇
神经病学   3978篇
特种医学   3255篇
外科学   7496篇
综合类   236篇
现状与发展   1篇
一般理论   17篇
预防医学   2733篇
眼科学   1240篇
药学   5083篇
  1篇
中国医学   624篇
肿瘤学   4837篇
  2023年   299篇
  2022年   1286篇
  2021年   2059篇
  2020年   987篇
  2019年   1294篇
  2018年   1677篇
  2017年   1245篇
  2016年   1763篇
  2015年   2567篇
  2014年   3071篇
  2013年   3517篇
  2012年   5321篇
  2011年   4818篇
  2010年   2828篇
  2009年   2396篇
  2008年   3435篇
  2007年   3197篇
  2006年   2669篇
  2005年   2375篇
  2004年   2030篇
  2003年   1694篇
  2002年   1450篇
  2001年   1380篇
  2000年   1273篇
  1999年   923篇
  1998年   437篇
  1997年   324篇
  1996年   276篇
  1995年   236篇
  1994年   190篇
  1993年   179篇
  1992年   340篇
  1991年   332篇
  1990年   291篇
  1989年   307篇
  1988年   277篇
  1987年   276篇
  1986年   202篇
  1985年   188篇
  1984年   138篇
  1983年   123篇
  1982年   82篇
  1981年   72篇
  1980年   55篇
  1979年   87篇
  1978年   72篇
  1977年   55篇
  1976年   73篇
  1975年   63篇
  1974年   60篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
Torsion of greater omentum is a rare cause of acute abdomen. However, it should be included in the differential diagnoses in addition to acute cholecystitis, acute appendicitis, cecal diverticulitis, and other variable causes of acute abdomen. Diagnosis is usually made at laparotomy for suspected appendicitis. In some cases, computed tomography demonstrates a successful preoperative detection of omental torsion. We report a case of surgically and pathologically proven torsion with subsequent infarction of greater omentum presented as an acute abdominal pain.  相似文献   
93.
The conjugate of antisense c-raf oligonucleotide (ODN) and poly(ethylene glycol) (PEG) was synthesized for intracellular ODN delivery. When combined with polyethylenimine (PEI), the ODN-PEG conjugate self-associated to form polyelectrolyte complex micelles in aqueous solution. The effective hydrodynamic diameter of the micelles was ca. 70 nm with a narrow size distribution. Flow cytometry analysis indicated that the cellular uptake of the micelles by A2780 cells was much higher than that of ODN alone. The micelles also showed a superior antiproliferative activity against ovarian cancer cells in vitro and in vivo.  相似文献   
94.
RASER: a new ultrafast magnetic resonance imaging method.   总被引:1,自引:0,他引:1  
A new MRI method is described to acquire a T(2)-weighted image from a single slice in a single shot. The technique is based on rapid acquisition by sequential excitation and refocusing (RASER). RASER avoids relaxation-related blurring because the magnetization is sequentially refocused in a manner that effectively creates a series of spin echoes with a constant echo time. RASER uses the quadratic phase produced by a frequency-swept chirp pulse to time-encode one dimension of the image. In another implementation the pulse can be used to excite multiple slices with phase-encoding and frequency-encoding in the other two dimensions. The RASER imaging sequence is presented along with single-shot and multislice images, and is compared to conventional spin-echo and echo-planar imaging sequences. A theoretical and empirical analysis of the spatial resolution is presented, and factors in choosing the spatial resolution for different applications are discussed. RASER produces high-quality single-shot images that are expected to be advantageous for a wide range of applications.  相似文献   
95.
96.
To elucidate the mechanisms by which thiamine deficiency affects hepatic microsomal monooxygenase activities, the effect of thiamine deficiency on two constitutive cytochrome P450 isozymes, P450IIE1 and P450IIC11, was investigated, using weanling male Sprague-Dawley rats. The clinical signs of thiamine deficiency were apparent after feeding a thiamine-deficient diet for 3 weeks. Thiamine deficiency caused an increase in P450IIE1, which was determined by N-nitrosodimethylamine demethylase assay and immunoquantitation of P450IIE1. This increase in the P450IIE1 level was mainly attributed to thiamine deficiency per se but not to dietary restriction. Ketone bodies were not elevated in thiamine-deficient rats, whereas ketone bodies were elevated and may have served as inducing factors in calorically restricted pair-fed animals. Injections of pyruvate or pyrithiamine in addition to thiamine deficiency did not potentiate the induction effect. On the other hand, thiamine deficiency did not affect the level of P450IIC11 during the 3 weeks of feeding the thiamine-deficient diet. In addition, thiamine deficiency increased cytosolic glutathione S-transferase activity but not steroid isomerase activity. The present study demonstrates the specificity of thiamine deficiency per se in the induction of P450IIE1 which does not involve an increase in the ketone body level.  相似文献   
97.
Abstract: Juvenile xanthogranuloma is a xanthomatous and granulomatous condition that frequently arises before 1 year of age and mainly occurs on the head and trunk. We report a rare solitary juvenile xanthogranuloma on the right palm of a 10-year-old girl, present for one year. This solitary involvement of the palm has been reported only twice before.  相似文献   
98.
Adverse reaction to intravenous gadoteridol   总被引:1,自引:0,他引:1  
  相似文献   
99.
The monoclonal antibody MAb 1-7-1, which specifically binds to cytochromes P-450IA1 and P-450IA2 in 3-methylcholanthrene-induced rat liver microsomes, was used to identify a cytochrome P-450IA1 homologue in human lung microsomes. Although MAb 1-7-1 had similar affinity constants for human and rat microsomes, the amount bound to human lung microsomes was severalfold lower than that bound to microsomes from untreated rat or rabbit lung and much lower than the amount bound to 3-methylcholanthrene-induced rat lung or liver microsomes. The amount bound to untreated baboon lung microsomes was similar to that bound to human lung microsomes. Three cytochrome P-450IA1-catalyzed activities, 7-ethoxyresorufin O-deethylase, 7-ethoxycoumarin, O-deethylase, and aryl hydrocarbon hydroxylase, were measurable in human lung microsomes, but the cytochrome P-450IA2-dependent activity acetanilide 4-hydroxylase was not. MAb 1-7-1 inhibited, and its binding correlated strongly with, 7-ethoxyresorufin O-deethylase activity (r = 0.92, p less than 0.01) in human lung microsomes. 7-Ethoxyresorufin O-deethylase activities in human lung were similar to those measured in untreated baboon lung but considerably lower than those present in untreated rabbit lung, untreated or 3-methylcholanthrene-induced rat lung and liver, or human liver. We conclude that MAb 1-7-1 recognizes a cytochrome P-450IA1 homologue in human lung and that no cytochrome P-450IA2 homologue is detected. Cytochrome P-450IA1 is expressed in human lung at relatively low levels, similar to those observed in untreated primate (baboon) lung. The majority of the 19 human lung samples examined do not exhibit a permanent polycyclic aromatic hydrocarbon-induced state with respect to this isozyme.  相似文献   
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